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Link: MDEA 2006: Changing Healthcare Delivery through New Technologies.
The IDI-MRSA assay, developed by GeneOhm Sciences Inc. (San Diego), is a qualitative in vitro diagnostic test for the direct detection of nasal colonization by methicillin-resistant Staphylococcus aureus (MRSA) to help prevent and control MRSA infections in healthcare settings. In March, Becton Dickinson acquired GeneOhm, which will now be known as BD Diagnostics– GeneOhm business unit. Infection control programs that use active surveillance to identify patients and strict application of barrier precautions for patients colonized or infected with MRSA have shown success in controlling MRSA. The company’s IDI-MRSA assay provides results in just two hours of lab time compared with the 16–72 hours required for a conventional culture. According to the company, such definitive, rapid results combined with earlier treatment intervention can significantly improve patient outcomes, prevent outbreaks, and control hospital costs. Without active surveillance testing for MRSA, most colonized patients go undetected. “MRSA is increasing at an alarming rate in hospitals, carrying a heavy burden of mortality and morbidity. In the United States alone, CDC estimates MRSA accounts for 2 million infections, 8 million excess hospital days, and more than 90,000 deaths per year,” explains Peter Klemm, president of BD Diagnostics–GeneOhm. “In fact, it is ranked as the fifth-leading cause of death in hospitals.”
Link: The Independent Online.
Campbellford Memorial Hospital has been given six months to make changes in its laboratory after it performed poorly in a series of bacteriology surveys conducted over a two year period. The lab made “five significant and eight lesser errors” identifying test samples given it by a provincial “regulatory watchdog” in 2004-05, hospital CEO Kelly Isfan reported at the board of directors’ monthly meeting April 4. The “cumulative poor performance” placed CMH “among the top 10 per cent of labs with the highest error scores,” she said. But there’s no reason for patients to become anxious. Ms. Isfan said the hospital does a “good job” processing bacteriology specimens taken from blood, urine and throat swabs that make up 90 per cent of the 320 routine tests it performs monthly to identify possible infections. With those specimens it’s also looking for two antibiotic-resistant “superbugs” in particular, MRSA and VRE, that can cause problems for hospitals.
Link: Journal of Clinical Microbiology.
Few studies have assessed the time to blood culture positivity as a predictor of clinical outcome in bloodstream infections (BSIs). The purpose of this study was to evaluate the time to positivity (TTP) of blood cultures in patients with Staphylococcus aureus BSIs and to assess its impact on clinical outcome. We performed a historical cohort study with 91 adult patients with S. aureus BSIs. TTP was defined as the time between the start of incubation and the time that the automated alert signal indicating growth in the culture bottle sounded. Patients with BSIs and TTPs of culture of ≤12 h (n = 44) and >12 h (n = 47) were compared. Septic shock occurred in 13.6% of patients with TTPs of ≤12 h and in 8.5% of patients with TTP of >12 h (P = 0.51). A central venous catheter source was more common with a BSI TTP of ≤12 h (P = 0.010). Univariate analysis revealed that a Charlson score of ≥3, the failure of at least one organ (respiratory, cardiovascular, renal, hematologic, or hepatic), infection with methicillin-resistant S. aureus, and TTPs of ≤12 h were associated with death. Age, gender, an APACHE II score of ≥20 at BSI onset, inadequate empirical antibiotic therapy, hospital-acquired bacteremia, and endocarditis were not associated with mortality. Multivariate analysis revealed that independent predictors of hospital mortality were a Charlson score of ≥3 (odds ratio [OR], 14.4; 95% confidence interval [CI], 2.24 to 92.55), infection with methicillin-resistant S. aureus (OR, 9.3; 95% CI, 1.45 to 59.23), and TTPs of ≤12 h (OR, 6.9; 95% CI, 1.07 to 44.66). In this historical cohort study of BSIs due to S. aureus, a TTP of ≤12 h was a predictor of the clinical outcome.
Link: Journal of Clinical Microbiology.
Rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) by PCR can be performed directly from nasal specimens with the IDI-MRSA assay. To improve the efficiency of screening, we evaluated the performance of the IDI-MRSA assay for the detection of MRSA from pooled and unpooled specimens cultured in a selective broth. Of the 287 specimens evaluated, 71 were culture and PCR positive, 203 were culture and PCR negative, 3 were culture positive and PCR negative, 8 were culture negative and PCR positive, and 2 remained inhibited. A methicillin-susceptible Staphylococcus aureus isolate was recovered from five of the eight specimens with false-positive PCR results. Compared to the results of culture, the sensitivity, specificity, and negative and positive predictive values of the IDI-MRSA assay for detection of MRSA from broth were 96%, 96%, 90%, and 98%, respectively. Following implementation of the IDI-MRSA assay, PCR-positive broths were subcultured for evaluation of assay performance. Of the 298 IDI-MRSA assay-positive broths, the results for 103 could not be confirmed by culture. A methicillin-susceptible S. aureus (MSSA) isolate was recovered from 77 of these 103 broths. Repeat testing by the IDI-MRSA assay directly with the MSSA isolates confirmed the original positive PCR result. The positive predictive value of the IDI-MRSA assay fell from 90% during the evaluation phase to 65% postimplementation. The IDI-MRSA assay performed well for the detection of MRSA from a selective broth compared to the performance of the detection of MRSA from culture. However, because of the burden associated with implementation of infection control precautions, cultures remain essential in confirming positive IDI-MRSA results.
Link: News
After controlling for other factors, methicillin resistance remained a significant risk factor for 14-day mortality for patients with MRSA BSI, Dr. Cunney stressed, although age, length of stay, and other factors become more significant for in-hospital and 30-day mortality. By way of potential explanation, he said, "I suspect that what is happening is that once you go beyond the 14-day mortality, the other risk factors -- such as underlying illness, age and so forth -- become more important, and you would expect that if methicillin resistance has an impact on mortality, that impact would occur early, because it would be related to treatment options." This study thus indicates the need for early identification of methicillin resistance in this population, and highlights the way in which such enhanced surveillance analyses can be used to determine the most appropriate measures for the control of MRSA infections, he concluded.
Link: RedOrbit
A doctor was celebrating last night after winning an award for developing a test to cut the diagnosis time for hospital bug MRSA. Operational services manager at the Freeman Hospital in Newcastle, Dr Michael Ford, 44, (ok) of Morpeth, received the NHS Innovation Award at The Sage Gateshead, for his HDA Medium Test which identifies antibiotic resistance strains of MRSA within 24 hours, cutting the previous diagnosis time by half.
Link: Wound Monitor.
The University of Manchester has received �1m (€1.67m) to develop a new device able to "sniff out" harmful infections. The funding will be used to create a non-invasive wound monitor to treat patients with severe burns, skin ulcers or gaping wounds. The aim is to produce a device which is able to detect harmful bacteria in the air, which may signal the first signs of infection. When bacteria metabolises inside a wound molecules of that bacteria are emitted into the air. Current methods rely on medical staff taking swabs from a wound and testing them in a lab, which can take several days. Professor Krishna Persaud, of The University of Manchester's School of Chemical Engineering and Analytical Science, who will coordinate the European-wide project, said: “Current methods make it difficult to detect infections at an early stage and can be extremely invasive causing the patient a great deal of discomfort”. “Our aim is to produce a non-invasive system that can monitor the state of a patients wounds simply by detecting bad bacteria in the air emitted from the wound. Using state of the sensors we will be able to detect and diagnose the presence of an infection almost instantaneously.”
Link: Journal of Medical Microbiology.
Between January and April 2002, a total of 271 strains of Staphylococcus aureus were isolated from clinical specimens at Toho University Omori Hospital, Japan, including 201 (74�2 %) which were identified as meticillin-resistant S. aureus (MRSA). However, 34 (12�5 %) were biochemically atypical, because they did not produce acid on mannitol salt agar or did not agglutinate in Staphaurex testing but were categorized as MRSA by PCR analysis and by antibiotic susceptibility. Three automatic identification systems, AutoScan-4� (Dade Behring), BD PhoenixTM (Becton Dickinson) and Vitek� 2 (bioM�rieux), were evaluated by testing these atypical S. aureus isolates. The AutoScan-4� and PhoenixTM systems identified all 34 isolates as S. aureus. Without additional tests such as Staphaurex, observation of colony pigment and haemolysins on sheep blood agar, Vitek� 2 identified only 16 isolates (47�1 %) as S. aureus with good or better confidence levels and misidentified one of the remaining isolates as Staphylococcus chromogenes. This study shows that it is possible to identify these physiologically atypical S. aureus isolates correctly by using the PhoenixTM and AutoScan-4� fully automatic identification systems.
Link: Arch Intern Med
Background No simple, cost-effective methods exist to identify patients at high risk for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci colonization outside intensive care settings. Without such methods, colonized patients are entering hospitals undetected and transmitting these bacteria to other patients. We aimed to develop a highly sensitive, simple-to-administer prediction rule to identify subpopulations of patients at high risk for colonization on hospital admission. Methods We conducted a prospective cohort study of adult patients admitted to the general medical and surgical wards of a tertiary-care facility. Data were collected using electronic medical records and an investigator-administered questionnaire. Cultures of anterior nares and the perirectal area were also collected within 48 hours of admission. Results Among 699 patients who enrolled in this study, 697 underwent nasal cultures; 555, perirectal cultures; and 553, both. Patient self-report of a hospital admission in the previous year was the most sensitive variable in identifying patients colonized with methicillin-resistant Staphylococcus aureus or with either organism (sensitivity, 76% and 90%, respectively). A prediction rule requiring patients to self-report having received antibiotics and a hospital admission in the previous year would have identified 100% of patients colonized with vancomycin-resistant enterococci. In the high-risk groups defined by the prediction rule, the prevalence of colonization by methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, or either organism were 8.1%, 10.2%, and 15.0%, respectively. Conclusion Patients with a self-reported previous admission within 1 year may represent a high-risk group for colonization by methicillin-resistant Staphylococcus aureus or vancomycin-resistant enterococci at hospital admission and should be considered for targeted active surveillance culturing.
Link: News from Oxoid.
Oxoid products for the detection and isolation of MRSA strains provide valuable confirmation of MRSA, quickly, conveniently and reliably. These include a range of suitable culture media, such as Oxoid Orsab selective medium (product code: CM1008 and SR0195) and Oxoid chromogenic MRSA agar (product code: PO1091A) for the detection of MRSA from routine swab samples, and a full range of products for antimicrobial susceptibility testing. In addition, the Oxoid PBP2' latex agglutination test (product code: DR0900A) detects MRSA specific antigen in suspect colonies within just a few minutes, providing rapid confirmation and allowing prompt initiation of appropriate treatment and control measures. This test has already proven to be invaluable in many hospitals around the world, providing results a day earlier than traditional methods.
Link: Journal of Medical Microbiology.
The identification of mannitol salt positive, coagulase-negative staphylococci (CNS) is often disregarded when Staphylococcus aureus is screened in clinical samples using mannitol salt agar. However, the emergence of CNS as important human pathogens has indicated that reliable methods for the identification of clinically significant CNS are of great importance in understanding the epidemiology of infections caused by them. The identification and molecular characterization of mannitol salt positive CNS from nasal samples of medical personnel and students is reported here. A total of 84 mannitol salt positive staphylococcal isolates were obtained from 240 nasal samples, of which 15 were CNS. The API STAPH system classified the CNS isolates into six species, and one-third of the isolates were identified with confidence levels of <80 %. 16S–23S rRNA intergenic spacer length polymorphism analysis (ITS-PCR) identified only two species (Staphylococcus haemolyticus and Staphylococcus saprophyticus). This identification was confirmed by antibiotyping, species-specific PCR and PFGE. The results from this study indicate that ITS-PCR is a potentially useful and reliable tool, enabling hospital laboratories to obtain rapid, full and accurate identification of CNS at the species level.
Link: Journal of Medical Microbiology.
Most routine laboratory detection of Staphylococcus aureus isolates is based on rapid agglutination test systems. Failure of agglutination assays to identify meticillin-resistant S. aureus strains (MRSA) has been demonstrated. The aim of this study was to evaluate six commercially available agglutination tests for the detection of meticillin-sensitive S. aureus (MSSA) and mecA-positive MRSA strains. The Dry Spot Staphytect Plus� test (Oxoid), the Pastorex Staph Plus� test (Bio-Rad), the Slidex Staph-Kit� and Slidex Staph Plus� test (bioM�rieux), the Staphaurex Plus� test (Remel) and the Staphylase Test� (Oxoid) were used. As determined by pulsed field gel electrophoresis, 52 distinct MRSA strains from five countries, 83 MSSA strains and 150 coagulase-negative staphylococci were included. Species identification and determination of susceptibility patterns were performed using colony morphology, Gram stain, catalase testing, tube coagulase testing, DNase testing, mannitol fermentation, susceptibility testing towards oxacillin by Etest�, coagulase gene PCR, fibrinogen receptor gene PCR and PCR of the mecA gene. Sensitivity of the agglutination tests ranged from 82�7 to 100�0 % for MRSA strains and 92�8 to 100�0 % for MSSA strains, respectively. Specificity of the test systems ranged from 91�3 to 99�1 %. None of the six agglutination assays produced correct reactions for all staphylococci tested. Only the Dry Spot Staphytect Plus� test correctly identified all 52 MRSA strains. For the other tests kits, sensitivity of MRSA detection was lower than for MSSA isolates. Depending upon the local MRSA prevalence and the parameter of interest (sensitivity or specificity), these test systems may be useful for routine diagnostic purposes.
Link: New Scientist Technology
A SOUTH AFRICAN inventor claims he has developed a watch that warns of malaria infection before symptoms appear. The wristwatch, from Gervans Trading, Port Elizabeth, is said to sound an alarm if it detects the malaria parasite. The inventor, Gervans Lubbe, says that the $280 gadget takes a tiny blood sample every six hours when a needle 0.5mm long is pushed into the skin through the watch base. He says that the sample is bathed in radio waves from a miniature source, generating a resonant signal that identifies the parasite. But he has not yet published any peer-reviewed papers on his method of detection. If it works, Lubbe hopes his next product will be a wristwatch to detect MRSA, the antibiotic-resistant hospital superbug.
Link: Clinical Microbiology Reviews
Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.
Link: Acolyte Biomedica.
Acolyte Biomedica has introduced a new platform for its BacLite Rapid MRSA test which promises to set the benchmark for laboratory based rapid screening. The new product, immediately available throughout the EU, offers the following features:. Rapid culture based screening test.
Ultra sensitive innovative detection technology.
Direct from specimen.
Confirmed negatives in five hours.
Confirmed positives next day.
Flexible throughput with up to 45 tests per run.
One minute hands on time per specimen.
More at the link above
Link: Detecting MRSA outbreaks.
German researchers have proposed an automated DNA sequence-based early warning system to detect methicillin-resistant Staphylococcus aureus (MRSA) outbreaks in hospitals, which they say could replace traditional slower techniques.
Outbreaks are usually identified manually from laboratory test results and patients' charts, which is time consuming. Established outbreaks are tracked by molecular typing. To improve the speed and reproducibility of this process, DNA sequence-based approaches are used but are usually still too expensive for routine use.
However, just typing a single locus -- the S. aureus protein A (spa) gene -- is fast and cost effective. In this month's PLoS Medicine, Dag Harmsen and colleagues from the Universities of M? and Hamburg investigated the combination of spa typing with a novel software program that automatically analyzes the spa sequences, links them to a database integrated with epidemiological information, and triggers an alarm if an outbreak is suspected. This approach was more sensitive at identifying outbreaks than classical surveillance techniques.
The combination of medical informatics and molecular laboratory techniques could help clinicians prevent limited clusters of MRSA expanding into large-scale outbreaks.
The rising global incidence of MRSA outbreaks in hospitals is a major concern because of the high mortality rate and the stringent hygiene requirements needed for patients who become infected.
Link: HighWire Press -- Medline Abstract.
The detection of methicillin-resistant Staphylococcus aureus (MRSA) usually requires the implementation of often rigorous infection-control measures. Prompt identification of an MRSA epidemic is crucial for the control of an outbreak. In this study we evaluated various early warning algorithms for the detection of an MRSA cluster. METHODS AND FINDINGS: Between 1998 and 2003, 557 non-replicate MRSA strains were collected from staff and patients admitted to a German tertiary-care university hospital. The repeat region of the S. aureus protein A (spa) gene in each of these strains was sequenced. Using epidemiological and typing information for the period 1998-2002 as reference data, clusters in 2003 were determined by temporal-scan test statistics. Various early warning algorithms (frequency, clonal, and infection control professionals [ICP] alerts) were tested in a prospective analysis for the year 2003. In addition, a newly implemented automated clonal alert system of the Ridom StaphType software was evaluated. A total of 549 of 557 MRSA were typeable using spa sequencing. When analyzed using scan test statistics, 42 out of 175 MRSA in 2003 formed 13 significant clusters (p < 0.05). These clusters were used as the "gold standard" to evaluate the various algorithms. Clonal alerts (spa typing and epidemiological data) were 100% sensitive and 95.2% specific. Frequency (epidemiological data only) and ICP alerts were 100% and 62.1% sensitive and 47.2% and 97.3% specific, respectively. The difference in specificity between clonal and ICP alerts was not significant. Both methods exhibited a positive predictive value above 80%. CONCLUSIONS: Rapid MRSA outbreak detection, based on epidemiological and spa typing data, is a suitable alternative for classical approaches and can assist in the identification of potential sources of infection.
Link: New Oxoid
Oxoid Limited has expanded its range of products for the growth and identification of methicillin resistant Staphylococcus aureus (MRSA) with the addition of a new Chromogenic Medium for screening of MRSA. Oxoid Chromogenic MRSA Agar (product code:P01091A UK/PO5083A other) has been specifically designed to screen clinical samples for the presence of MRSA, providing accurate, easy to read results in as little as 18 hours - up to 30 hours quicker than some alternative media that may require 48 hour incubations. There is no need to re-incubate negative plates, making it a true next-day test. Fast and accurate screening is extremely important for infection control programmes to be effective. The speed of detection using Oxoid Chromogenic MRSA Agar allows colonised patients to be targeted promptly for isolation and appropriate treatment, helping to minimise opportunities for transmission at the earliest opportunity. The accuracy of the new Oxoid medium helps to ensure that costly resources are targeted towards those who need it, especially in hospitals where the MRSA rate is high.
Link: News from Oxoid.
Oxoid has extended its range of products for the detection of methicillin resistant staphylococcus aureus (MRSA) with the addition of Staphaurex Plus, a rapid and convenient latex agglutination test that is able to detect MRSA in addition to methicillin susceptible staphylococcus aureus (MSSA). The latex particles in Staphaurex Plus are coated with fibrinogen and specific polyclonal antibodies directed towards difficult staph aureus strains, including MRSA. In the presence of target organisms, the latex particles agglutinate to give a strong and easily visible positive reaction. In the absence of target organism the particles remain in smooth suspension. The sensitivity of Staphaurex Plus is >98% for all staph aureus strains. Everything that is required to perform the test is provided in the kit, including reaction cards, mixing sticks and a control latex to eliminate non-specific agglutination. Kits are available in two sizes, 150 tests (product ref: 30950102) and 450 tests (product ref: 30950201), to suit both small and large workloads.
Link: Harnessing genomic research.
Regeneration of spinal nerve cells, a new way to personalise breast cancer treatment, rapid near-patient diagnosis of meningitis, MRSA and Chlamydia and effective vaccines to protect against salmonella are all important applications to have benefited from a £30M research programme built around harnessing knowledge of the human and other genomes. A key feature of this LINK Applied Genomics Programme has been effective collaboration between industry and academia aimed at accelerating the application of knowledge of genomics in biomedicine and healthcare.
Rapid diagnosis of infectious diseases- Scientists at the Universities of Bath and Glasgow, with colleagues from Stobhill Hospital and Atlas Genetics Ltd are miniaturising established molecular techniques and combining them with novel assays to develop a hand-held 'chip' that will allow doctors to identify specific bacteria in patient samples. In the future this chip could be used to for rapid diagnosis of dangerous diseases such as MRSA infection and bacterial meningitis, where fast confirmation is critical, or for potentially catastrophic but widespread and non-symptomatic infections such as that caused by Chlamydia.
Link: The Engineer Online
A product that can perform a rapid test for serious diseases such as meningitis, chlamydia and the hospital superbug MRSA is being developed by a new company Atlas Genetics, which is being launched using �500,000 funding and the expertise of academics at the University of Bath. Current hospital tests take up to 72 hours, by which time the patients may have become seriously ill and may have spread the disease. The new product, however, will enable hospitals and eventually GPs to perform tests on the spot and make decisions about treatment within 20 minutes. In use, the product will analyse a clinical sample of blood, urine or saliva and then indicate the presence, or absence, of DNA from the bacteria causing the disease.
An electronic nose that sniffs out infections could help hospitals tackle outbreaks of the antibiotic-resistant superbug MRSA. Culture tests routinely used to identify MRSA (methicillin-resistant Staphylococcus aureus) take two or three days to complete. This hampers attempts to manage outbreaks as infected patients remain untreated and at risk of infecting others. DNA-based tests are being trialled that promise to reduce test times to 2 hours, but now UK-based researchers have come up with a test using an electronic sniffer that could cut the time further, to just 15 minutes. Engineers at the University of Warwick and doctors at the Heart of England Hospital, Birmingham, say the electronic nose can recognise the unique cocktail of volatile organic compounds that S aureus strains excrete. E-noses analyse gas samples by passing the gas over an array of electrodes coated with different conducting polymers. Each electrode reacts to particular substances by changing its electrical resistance in a characteristic way. Combining the signals from all the electrodes gives a "smell-print" of the chemicals in the mixture that neural network software built into the e-nose can learn to recognise.
Link: PM's MRSA test hope.
A woman who confronted Tony Blair about hospital infections during the election has received a personally signed letter from him - setting out the government’s plans for tackling the problem. In the letter Mr Blair said he is hoping a two hour test for MRSA may be available by the end of the year. The letter was sent to Ruth Wollacott whose son James, aged 21, has been disabled by MRSA. When she met the Prime Minister in April, she wanted him to look into the lack of proper recording of MRSA cases in hospitals. The letter states: "As I said when we met, tackling MRSA and all healthcare-associated infections is a key priority for the NHS and this Government. It, I promise, remains so."
Link: News from Acolyte Biomedica.
Hospital microbiology laboratories seeking to play a more active role in infection control for MRSA can now get support from known and trusted distributors in the UK and Eire, says Acolyte Biomedica. The company, which manufactures the battlefield-inspired BacLite Rapid MRSA test, has appointed three distributors across the UK and Ireland. In Ireland companies within the Brennan group will sell and support the product. Both Isis in the republic and SMC in Northern Ireland have a strong offering of infection control products. On the UK mainland Bio-Stat, a company with a long track record in microbiology, adds the test to its range of products for microbiology laboratories. BacLite originated from UK Ministry of Defence work carried out at Porton Down on rapid detection of potential biological warfare pathogens.
Link: Interactive Investor.
ANGLE PLC said its venture company Acolyte Biomedica Ltd has launched its BacLite Rapid MRSA 'superbug' test and that the Salisbury District Hospital takes delivery of the first system. Giving same day results, the test will allow hospitals to screen patients and hospital workers for the presence of the superbug. Andrew Newland, chief executive of ANGLE said: "This launch is a significant milestone for Acolyte and underlines the high value of the technology and the clinical importance of such a testing system.
Link: Hubmed
All the bottles that yielded methicillin-resistant S. aureus (MRSA), methicillin-sensitive S. aureus (MSSA) or methicillin-resistant CoNS (MRCoNS) strains were correctly identified by the nucA and mecA PCR assays. One bottle that yielded a mixed culture of MSSA and MRCoNS gave positive results for both genes. In the 21 bottles with methicillin-susceptible CoNS (MSCoNS), nucA PCR were negative, but two of these bottles gave positive results for the mecA gene. The sensitivity and specificity of the nucA gene assay were 100%. The sensitivity and specificity of the PCR assay for detection of methicillin resistance with the mecA gene were 100% and 97.5%, respectively. CONCLUSION. This is a sensitive and highly specific method for identifying staphylococci in positive blood cultures, allowing discrimination between methicillin-susceptible and -resistant strains in less than 3 hours after Gram stain.
Link: Hospital surveillance program..
BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has spread worldwide and is responsible for significant morbidity, mortality, and health care costs. Control strategies to limit the emergence and spread of this organism rely on rapid and sensitive tests for detection of MRSA carriage. However, the standard surveillance culture method for detecting MRSA is labor intensive and time-consuming (2-3 days per procedure). There is thus a need for a rapid and accurate method to screen for MRSA carriage. METHODS: We recently developed an easy-to-use real-time polymerase chain reaction (PCR) assay suitable for specific detection of MRSA in nasal specimens in <1 h. We studied the efficacy of our new PCR assay in routine screening for nasal MRSA carriage during a hospital surveillance program. A total of 331 nasal specimens obtained from 162 patients at risk for colonization were tested by both the standard mannitol agar culture method and our PCR assay. RESULTS: The PCR assay detected MRSA in all 81 samples that were culture positive for MRSA. The PCR assay detected 4 additional MRSA-positive specimens, for a specificity of 98.4%, a positive predictive value of 95.3%, and a sensitivity and negative predictive value of 100%. CONCLUSIONS: This novel PCR assay allows reliable identification of MRSA carriers in <1 h. This test should facilitate the efficacy of MRSA surveillance programs.
Link: HighWire Press -- Medline Abstract.
To compare a duplex light cycler polymerase chain reaction (PCR) assay targeting the mecA gene and a Staphylococcus aureus (S. aureus) specific marker and the conventional method. METHODS: We evaluated 400 samples sent to the laboratory in Zayed Military Hospital, Abu Dhabi, United Arab Emirates for methicillin-resistant Staphylococcus aureus (MRSA) screening and routine bacterial cultures from the period January 2003 to January 2004. All samples were cultured and identified according to the National Committee for Clinical Laboratory Standard guidelines. Staphylococcus aureus were tested for methicillin susceptibility according to the guidelines. All Staphylococcus positive cultures underwent testing by the new duplex light cycler PCR assay. We used 2 pairs of primers: mecA and nuc. Both targeted the mecA gene and the S. aureus-specific marker. Results obtained from the 2 methods (conventional culture method and the real-time PCR method) were compared. RESULTS: From the 400 samples tested, a total of 9 MRSA were detected by both methods. The real-time PCR method took less than 60 minutes to complete. CONCLUSION: This study shows that the duplex light cycler PCR assay method is very sensitive, very specific, and less time consuming in diagnosing MRSA from bacterial cultures.
Link: Journal of Clinical Microbiology.
To identify the most rapid and reliable technique for recovery and identification of Staphylococcus aureus small-colony variants (SCVs), the colonial appearance of 106 isolates representing SCVs and the normal phenotype were evaluated on two newly described chromogenic agar media. Although almost all of the SCVs grew on the chromogenic agar media, they did not exhibit a change of color. In comparison with conventional media, S. aureus ID agar (SAID; bioM�rieux, La Balme Les Grottes, France) showed the most reliable results, with 49 of 53 SCVs tested growing either as an SCV colony or with a normal phenotype after only 24 h of incubation. Growth of SCVs was often not detected before 72 h of incubation on some of the media tested. In conclusion, the most accurate and rapid method to detect both the species S. aureus and the SCV phenotype is to inoculate specimens onto both Columbia blood agar and SAID.
Link: Journal of Clinical Microbiology.
CHROMagar MRSA was evaluated for its ability to identify methicillin-resistant Staphylococcus aureus (MRSA). A well-defined collection consisting of 216 MRSA strains and 241 methicillin-susceptible Staphylococcus aureus isolates was used. The sensitivity of CHROMagar MRSA after 24 h of incubation was 95.4%, increasing to 100% after 48 h. The specificity was already 100% after 24 h.
Link: Journal of Antimicrobial Chemotherapy.
Objectives: To evaluate the usefulness of cefoxitin when used as a surrogate marker for the detection of methicillin resistance. Patients and methods: Eight hundred and seventy-one strains of Staphylococcus aureus, collected from eight tertiary referral centres serving diverse socio-economic populations, were included in the study using NCCLS disc diffusion and the agar dilution methods. Results: Using cefoxitin and NCCLS criteria for disc diffusion, the sensitivity and specificity for recognizing methicillin resistance were both 100%. Similar results were obtained when the strains were tested by the agar dilution method. The cefoxitin MICs for methicillin-susceptible strains were ≤ 4 mg/L. Conclusions: Testing with cefoxitin as a surrogate marker for the detection of methicillin resistance was very accurate with both disc diffusion and agar dilution methods. Such testing clearly distinguished methicillin-resistant strains of S. aureus from methicillin-susceptible strains.
Link: Infection Control Nurses Asociation.
MRSA: Guidelines for the Laboratory Diagnosis and Susceptibility Testing of Meticillin-Resistant Staphylococcus aureus (MRSA)
The above draft guidelines have today been issued for open consultation for a period of four weeks commencing Monday 28th March 2005. The consultation period will end on Friday 22nd April 2005. Personalised copies were issued to the Chairs/Presidents/Chief Executives of 91 Royal Colleges, specialist societies and other external organisations. The draft guidelines will also be placed on the websites of the HIS and ICNA. Responses will be forwarded to the Chair, David Edwards, who will consult with relevant working party members during the course of, and immediately following, the consultation.
Link: Evening Star - Lively, Loyal, Local.
AN IPSWICH woman waited for five weeks before being told she had MRSA. Julie Sadler is today demanding answers as to why doctors at Ipswich Hospital waited so long to tell her she had the bug - which she fears she could have passed on to other patients on her ward. The 46-year-old had a hysterectomy at Ipswich Hospital in January and was swabbed for the bacteria when doctors noticed her wounds were not healing properly. Shortly after this she was allowed home and did not hear anything else from doctors about the tests so assumed they must have been negative. It was not until five weeks later she received a phone call to say the tests had proved positive for MRSA.
Link: Evening Star - Lively, Loyal, Local.
QUESTIONS are today being asked about the accurate recording of MRSA on death certificates, following the tragic case of Woodbridge baby Luke Day. Patient groups and politicians say Ipswich Hospital's initial failure to put MRSA on Luke's death certificate could be indicative of a much more widespread problem. Tony Field, chairman of MRSA Support - a support group for anyone who has been affected by the bug, said: "I would say that in the case of more than half our members who've had loved ones die of MRSA, it was not recorded on their death certificates. "I think it's down to a fear of what the population might think. "I would like to see a complete change of attitude from top government officials downward and have them be frank and open about hospital acquired infections."
A spokesman for Ipswich Hospital said he was confident that all procedures had been properly followed. He said: "The important thing is that the family were told about the MRSA as soon as we knew. It was not a case of the hospital trying to hide it from them."
Link: HighWire Press -- Medline Abstract.
In respect to epidemiological survey, plasmids profiles and REAP seems to discriminate more respect to antibiotic sensitivity tests but at the same time neither of them were 100% accurately differential. According to the plasmid profile of the 3rd MSSA (Turkey) group, a multi-drug resistance by antibiotic susceptibility tests were noticed and showed the same plasmid profile in MRSA first subgroup of the 3rd group, but the same groups were different in REAP tests. In order to distinguish the discriminatory power of the strains, where REAP is better than plasmid profile and antibiotic sensitivity tests, we may formulate the statement into the following; REAP > plasmid profile > antibiotic sensitivity tests. For typing and gathering of epidemiological data, it is suggested that all 3 methods should be employed in clinical laboratories as they are cheap, practical and easily interpreted.
Link: icSolihull
PATIENTS in Solihull could benefit from a new technique aimed at stopping the spread of hospital superbug MRSA. The new procedure will help hospitals discover the source of the killer bug and will be tested at Heartlands Hospital. It was developed by Peter Hawkey, a consultant at Birmingham Heartlands and Solihull NHS Trust. Health Secretary John Reid revealed the move on Monday when he announced that cases of MRSA have dropped dramatically according to latest figures. Dr Hawkey has developed a technique for detecting MRSA within two hours - much faster than the current test, which takes days to complete. This will allow doctors to determine whether patients became infected at hospital or brought infections in with them.
Link: MRSA fall.
He announced that two hospitals in Birmingham and London would be piloting a new swab test said to detect MRSA within a couple of hours, rather than the two days it takes to culture the staphylococcus aureus bacteria at present. Although the test is expensive and at the moment only used in the US and Canada, the health minister, Lord Warner, said: "If it works, we as government will want to see this used across the NHS." With 6.6 million people undergoing surgery last year, the bill is potentially enormous, but Lord Warner hinted that if MRSA could be brought under some sort of control - it will never be eliminated - then the most at-risk groups could be swab tested before they come into hospital.
Link: Journal of Clinical Microbiology.
The DiversiLab System, which includes microfluidics-based detection, reagent kits, and software for data processing and analysis, is an automated method using repetitive sequence-based PCR (rep-PCR) for microbial strain typing. To assess the reliability of the DiversiLab System for strain characterization of Staphylococcus aureus, we tested clinical isolates sent to ARUP Laboratories for typing and compared results to those of pulsed field electrophoresis (PFGE) aided by the cluster analysis provided by BioNumerics software. spa typing was performed when the results of these two methods for an outbreak were not concordant. The study included 89 S. aureus isolates (65 mecA positive, 24 mecA negative) from 19 outbreaks (2 to 11 isolates/outbreak). The DiversiLab and PFGE-BioNumerics results were concordant for 15 of the 19 outbreaks. For the remaining four outbreaks, there was partial concordance between the two methods. spa typing results were the same as or more similar to rep-PCR results for three of those outbreaks and were more similar to PFGE results for one. With regard to performance, the DiversiLab system was considerably less labor intensive than PFGE and provided results in less than 24 h, compared with 2 to 3 days for PFGE. Additionally, the Web-based DiversiLab software provides standardized comparisons among isolates almost instantaneously and generates user-friendly, customized reports.
Link: Journal of Antimicrobial Chemotherapy.
Objectives: To evaluate the usefulness of cefoxitin when used as a surrogate marker for the detection of methicillin resistance. Patients and methods: Eight hundred and seventy-one strains of Staphylococcus aureus, collected from eight tertiary referral centres serving diverse socio-economic populations, were included in the study using NCCLS disc diffusion and the agar dilution methods. Results: Using cefoxitin and NCCLS criteria for disc diffusion, the sensitivity and specificity for recognizing methicillin resistance were both 100%. Similar results were obtained when the strains were tested by the agar dilution method. The cefoxitin MICs for methicillin-susceptible strains were ≤ 4 mg/L. Conclusions: Testing with cefoxitin as a surrogate marker for the detection of methicillin resistance was very accurate with both disc diffusion and agar dilution methods. Such testing clearly distinguished methicillin-resistant strains of S. aureus from methicillin-susceptible strains.
Link: Journal of Antimicrobial Chemotherapy.
To evaluate the performance of oxacillin, cefazolin, cefoxitin, cefotaxime and imipenem discs; Etest for oxacillin; microdilution; agar screening plates with 2 and 6 mg/L of oxacillin; and PBP2' agglutination for detection of methicillin-resistant Staphylococcus aureus (MRSA). Conclusions: In the absence of availability of molecular biology techniques, the cefoxitin disc was the best predictor of methicillin resistance in S. aureus from among the techniques tested.
Link: HighWire Press -- Medline Abstract.
Plasmid profile analysis (PPA), random amplification of polymorphic DNA (RAPD) and pulsed field gel electrophoresis (PFGE) are the three most valuable epidemiological tools for genotyping of methicillin resistant Staphylococcus aureus (MRSA) strains. Aim of this study was to evaluate these three methods in respect to their cost, reproducibility, and discriminatory power. Eighty one nosocomial MRSA isolates with unknown genetic and epidemiological relatedness from Training Hospital of Gulhane Military Medical School, were genotyped by PPA, RAPD, and PFGE methods. All isolates (100%) were typed by RAPD and PFGE, however, eight (9.9%) isolates could not be typed by PPA since they lacked plasmid DNA. Reproducibilities of all the three methods were found to be 100 percent. Discriminatory powers of PPA, RAPD and PFGE methods were calculated as 48.6%, 61.1% and 80.1%, respectively. In conclusion, out of the three methods tested, PFGE allowed the most effective discrimination of MRSA strains. However, PFGE was more time consuming and technically demanding, and required use of specialized and expensive equipment. Although PPA and RAPD were less discriminatory than PFGE, these methods were technically simple, rapid and cheaper. When PPA and RAPD were used in combination, they had equal discriminatory power to PFGE. Thus, it should be emphasized that PPA and RAPD methods could be preferred for initial screening purposes while PFGE should be used as a confirmatory test in genotyping of MRSA isolates.
Link: American Journal of Epidemiology.
Comorbidity is a known risk factor for antibiotic-resistant bacterial infections. Although aggregate comorbidity measures are useful in epidemiologic research, none of the existing measures was developed for use with this outcome. This study compared the utility of two comorbidity measures, the Charlson Comorbidity Index and the Chronic Disease Score, in assessing the comorbidity-attributable risk of nosocomial infections with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE). Two case-control studies were conducted at the University of Maryland Medical System in Baltimore, Maryland. Cases were inpatients with a first positive clinical culture of MRSA or VRE at least 48 hours postadmission (July 1, 1998–July 1, 2001). Three inpatient controls were randomly selected per case. The MRSA study included 2,164 patients, and the VRE study included 1,948. The scores’ discrimination and calibration were measured by using the c statistic and Hosmer-Lemeshow chi-square test. The Charlson Comorbidity Index (c = 0.653) and Chronic Disease Score (c = 0.608) were similar discriminators of MRSA and VRE (c = 0.670 and c = 0.647, respectively). Calibration of the scores was poor for both outcomes (p < 0.05). A revised comorbidity measure specific to resistant infections would likely provide a better assessment of the comorbidity-attributable risk of antibiotic-resistant infections.
Link: icSouthlondon
LEWISHAM hospital has announced it is screening patients who are admitted via A&E for the superbug MRSA. In the autumn the hospital gave a commitment to Deptford Action Group for the Elderly (DAGE) that this would happen by January. A spokesman for the hospital said: "This is understood to be one of the most extensive investigations of MRSA at any UK hospital."
Link: HighWire Press -- Medline Abstract.
OBJECTIVE: To identify a strategy of MRSA screening (methicillin-resistant Staphylococcus aureus) on admission to geriatric rehabilitation units, which would lead to acceptable efficacy and cost compared with a reference maximaliste strategy combining all six sampling sites.
METHOD MRSA screening was conducted prospectively for 3 months in all the patients admitted to a geriatric follow-up and rehabilitation unit, using samples from the nostrils, armpits, urine scars cutaneous ulcers and sores. Six strategies were defined combing different sampling sites. Their efficacy and cost were compared with those of a maximaliste strategy combining the 6 sampling sites.
RESULTS: Combined screening of all six sites was the most effective but also the most expensive strategy. The least expensive strategy used only samples from ulcers and sores, but its efficacy was of only 45%. The strategy with the lowest loss of efficacy compared to the reference strategy combined the sampling of ulcers and sores and sampling from the nostrils: it was efficient in 91% and its cost was 2.5 fold lower than the cost of the reference strategy.
DISCUSSION: A preliminary, short term study established an MRSA screening strategy adapted to the specificities of a geriatric rehabilitation unit and its recruitment. The ability to define the optimal strategy for MRSA screening in a geriatric rehabilitation and follow-up unit may be an important factor in controlling the diffusion of MRSA.
Link: News Shopper.
EVERY patient admitted through A&E is now screened for the superbug MRSA as part of a bid to tackle infections. Lewisham Hospital implemented the system within three months following criticism last year over its processes for dealing with the deadly bug. Now the Lewisham High Street hospital says its record on cleanliness is better than ever and, with every surgical and A&E admission being screened, it has one of the most extensive MRSA investigation processes in the UK.
Link: icNewcastle
A superbug test kit is being developed by a Tyneside company for hospitals across the UK. Immunodiagnostic Systems, (IDS), which is based in Boldon Business Park in West Boldon, South Tyneside, hopes to dramatically reduce the time it takes to test for MRSA in hospitals throughout the UK. The firm is developing a testing kit which will be able to diagnose the deadly disease within five hours. At the moment it can take up to 72 hours for MRSA to be detected and the disease is costing the National Health Service around �1bn with ward closures and patients being isolated.
Link: ORSA - Oxacillin Resistant Staphylococcus Aureus.
Oxacillin Resistant Staphylococcus Aureus is the same thing as MRSA (Methicillin Resistant Staph.Aureus). The lab test for antimicrobial efficacy in the past used Methicillin, now uses Oxacillin. Why is Oxacillin tested instead of Methicillin? Oxacillin is more resistant to degradation in storage and is more likely to detect most heteroresistant strains. In addition, Methicillin is no longer commercially available in the United States. Antimicrobials like Oxacillin, Nafcillin, and Vancomycin now are used for treatment of S. aureus infections. The purpose of this site is to try to collect relevant information on ORSA and present it in a lay person-friendly format.
Link: Scotsman.com News
New technology which dramatically cuts the time taken to test for hospital superbug MRSA has been introduced in Plymouth. The new technique in use at Derriford Hospital cuts the time from testing patients for the bug to obtaining results from five days to three hours. The hospital is one of the first in the UK to invest in the cutting-edge technology to modernise screening for MRSA. Dr Peter Jenks, hospital director of infection control and prevention, said: “The purchase of this new screening equipment will help us in our ongoing fight to reduce MRSA.”
BD (Becton, Dickinson and Company), through its BD Diagnostics segment, today announced that the U.S. Food and Drug Administration has cleared the BBL(TM) CHROMagar(TM) MRSA product. This new prepared plated medium simplifies the process, decreases the time to result and offers high sensitivity and specificity for methicillin-resistant Staphylococcus aureus (MRSA) identification. BBL CHROMagar MRSA allows microbiology laboratories to identify patients colonized with MRSA more quickly and easily than the time-consuming and labor- intensive processes currently available. BBL CHROMagar MRSA allows for the direct detection and identification of most MRSA within 24 hours. The cost benefits associated with reducing nosocomial infections can be significant. "This technology will be extremely useful to those who wish to identify patients colonized with MRSA," said Dr. Bill Jarvis of Emory University School of Medicine and President, Jason and Jarvis Associates.
BD (Becton, Dickinson and Company), through its BD Diagnostics segment, today announced that the U.S. Food and Drug Administration has cleared the BBL(TM) CHROMagar(TM) MRSA product. This new prepared plated medium simplifies the process, decreases the time to result and offers high sensitivity and specificity for methicillin-resistant Staphylococcus aureus (MRSA) identification. BBL CHROMagar MRSA allows microbiology laboratories to identify patients colonized with MRSA more quickly and easily than the time-consuming and labor- intensive processes currently available. BBL CHROMagar MRSA allows for the direct detection and identification of most MRSA within 24 hours. The cost benefits associated with reducing nosocomial infections can be significant. "This technology will be extremely useful to those who wish to identify patients colonized with MRSA," said Dr. Bill Jarvis of Emory University School of Medicine and President, Jason and Jarvis Associates.
Link: Acolyte.
Acolyte Biomedica Limited is a privately-funded UK company developing proprietary diagnostic systems for clinical microbiology. Acolyte’s technology (‘BacLiteTM’) allows microbial detection and antibiotic sensitivity determination in 2-5 hours instead of days, reducing hospital costs and improving management of infectious disease patients. BacLite technology is unique within infectious disease diagnostics, providing antibiotic susceptibility testing (AST) and micro-organism detection direct from clinical specimens. BacLite technology was originally developed by the Defence Science & Technology Laboratory (Dstl) at Porton Down, a division of The UK Ministry of Defence. It exploits the bioluminescent detection of Adenylate Kinase (AK) for ultrasensitive antibiotic susceptibility and micro-organism detection. Acolyte has the exclusive license to BacLite for clinical microbiology and benefits from an ongoing collaboration with Dstl, which is also a shareholder in Acolyte.
Link: Guardian Unlimited
Prof Hawkey said the test would allow hospitals to see whether patients were infected with the same strain of MRSA, pointing to a common source, or different strains. Existing tests can only differentiate between the two most common strains of MRSA (methicillin-resistant staphylococcus aureus). The microbiologist, who is also professor of public health bacteriology at Birmingham University, said: "To give an analogy, current tests could differentiate between a horse and a zebra. But this new test can tell you whether it's a Shetland pony or a thoroughbred." Using current methods it can take up to three to four days to differentiate between the two main strains of MRSA, but Prof Hawkey said his test provided results within one day. The microbiologist has also been testing a new rapid method of screening for the MRSA superbug. The test devised by Canadian researchers can identify patients infected with MRSA within two hours. Existing screening methods take as long as two days. Prof Hawkey hopes to conduct a trial of the test, produced by Infectio Diagnostics Ltd, at Heartlands hospital. At a price of £15 per patient, offering it routinely to all hospital patients would cost the NHS a fortune. Current testing costs between £5 to £8.
Link: Times Online - Britain.
Scientists have developed a test that can identify the MRSA hospital superbug in two hours instead of the two to three days that present tests take. MRSA kills at least 5,000 people a year. Professor Peter Hawkey of Birmingham Heartlands Hospital, who led the team, said that the time saved could cut deaths from infections acquired in hospital.
Link: Clinical Microbiology.
Screening for colonization with methicillin-resistant Staphylococcus aureus (MRSA) is a key aspect of infection control to limit the nosocomial spread of this organism. Current methods for the detection of MRSA in clinical microbiology laboratories, including molecularly based techniques, require a culture step and the isolation of pure colonies that result in a minimum of 20 to 24 h until a result is known. We describe a qualitative in vitro diagnostic test for the rapid detection of MRSA directly from nasal swab specimens (IDI-MRSA; Infectio Diagnostic, Inc., Sainte-Foy, Qu�bec, Canada), based upon a real-time PCR and direct detection of MRSA via amplicon hybridization with a fluorogenic target-specific molecular beacon probe.