MRSA Infection

Fitness cost: a bacteriological explanation for the demise of the first international methicillin-resistant Staphylococcus aureus epidemic

Fitness cost: a bacteriological explanation for the demise of the first international methicillin-resistant Staphylococcus aureus epidemic.

Results Significant fitness costs of 2%–15% were determined for the MRSA isolates studied. There was a significant negative correlation between number of antibiotic resistances and relative fitness. Multiple regression analysis found significantly independent negative correlations between fitness and the presence of mecA or streptomycin resistance. Mathematical modelling confirmed that fitness costs of the magnitude carried by these isolates could result in the disappearance of MRSA prevalence during a time span similar to that seen in Denmark. Conclusions We propose a significant fitness cost of resistance as the main bacteriological explanation for the disappearance of the multiresistant complex 83A MRSA in Denmark following a reduction in antibiotic usage.

Large city hospitals 'breed and spread' MRSA

BBC News - Large city hospitals 'breed and spread' MRSA.

Hospitals in large cities are the breeding grounds of the superbug MRSA which then spreads to other hospitals as patients are transferred, researchers believe.

The Edinburgh University team made the discovery by tracking MRSA's movements using its genetic code as a tag.

In the study, the infection started its journey in large city centre hospitals - in London and Glasgow - and then spread to smaller local hospitals.

The work appears in the journal PNAS.

Prevalence and risk factors for MRSA colonization in a diabetic outpatient population

Prevalence and risk factors for methicillin-resistant Staphylococcus aureus colonization in a diabetic outpatient population: A prospective cohort study.

Out of the 304 patients evaluated, 127 (41.9%) were colonized with S aureus and 30 (9.9%) were colonized with MRSA. Overall, 23.6% of all S aureus isolates were MRSA. In multivariate analysis, factors independently associated with an increased risk of MRSA colonization included the presence of connective tissue disease (odds ratio, 7.075; 95% confidence interval, 2.157-23.209; P = .001) and insulin therapy (odds ratio, 3.910; 95% confidence interval, 1.652-9.251; P = .002). Conclusions The prevalence of MRSA colonization in our sample of diabetic outpatients was 9.9%. Independent risk factors for MRSA colonization were the presence of connective tissue disease and insulin use. A better understanding of the epidemiology and risk factors for nasal MRSA colonization in the persons with diabetes may have significant implications for the treatment and prevention of MRSA infections.

Occurrence of and risk factors for methicillin-resistant Staphylococcus aureus at a teaching hospital in Philadelphia

Occurrence of and risk factors for methicillin-resistant Staphylococcus aureus at a teaching hospital in Philadelphia.

Manual medical record mining and data analysis were performed at a tertiary care university teaching hospital to establish the rate of occurrence of and risk factors for infection with methicillin-resistant Staphylococcus aureus (MRSA). Patients with surgical site infections had the highest rate of MRSA infection, representing 59% of the MRSA infections recorded. The mortality rate in patients with relapsed MRSA was 45% (13 of 30), compared with no deaths in 149 new MRSA cases. The majority of deaths in patients with relapsed MRSA occurred in the intensive care unit.

MRSA tailors virulence mechanisms to the hospital setting

MRSA tailors virulence mechanisms to the hospital setting.

The findings of new research by UCD scientists led by Conway Fellow, Dr Jim O’Gara from UCD School of Biomolecular & Biomedical Science indicate that the so-called ‘super-bug’, MRSA sacrifices virulence potential for antibiotic resistance. When the pathogen Staphylococcus aureus becomes resistant to methicillin, it also alters the way in which it produces a biofilm. This coating by colonies of the pathogen can form on prosthetic devices implanted in patients for diagnostic or therapeutic reasons and cause infection. Patients with implanted devices are typically in an intensive care setting in hospital and have lowered immunity. They are more susceptible to infection even from a less virulent MRSA.

Risk factors and mortality in staph infections

Risk factors and mortality of healthcare-associated and community-acquired Staphylococcus aureus bacteraemia - Bassetti - 2011 - Clinical Microbiology and Infection - Wiley Online Library.

. Five variables were independently associated with HCA ≥48 h SAB: presence of central venous catheter, solid tumour, chronic renal failure, previous hospitalization and previous antibiotic therapy. Significant risk factors for HCA <48 h SAB were: Charlson Comorbidity Index ≥3, previous hospitalization, living in long-term care facilities and corticosteroid therapy. Factors independently associated with CA SAB were: diabetes mellitus, HIV infection and chronic live disease. Patients with HCA <48 h SAB were significantly more likely to receive initial inadequate antimicrobial treatment than patients with CA or HCA ≥48 h SAB (44.8% versus 33.3% and 31.5%, respectively). Logistic-regression analysis identified three variables as independent predictors of mortality: presentation with septic shock, infection with methicillin-resistant S. aureus, and initial inadequate antimicrobial treatment. More than half of patients with SAB have MRSA strains and presentation with septic shock, and inappropriate empirical therapy was associated with increased mortality.

MRSA increasing as percentage of staph

The changing epidemiology of Staphylococcus aureus bloodstream infection: A multi-national population-based surveillance study. - Laupland - Clinical Microbiology and Infection - Wiley Online Library.

Although the epidemiology of Staphylococcus aureus bloodstream infection (BSI) has been changing international comparisons are lacking. We sought to determine the incidence of S. aureus BSI and assess trends over time and by region. Population-based surveillance was conducted nationally in Finland and regionally in Canberra, Australia, western Sweden, and three areas in each of Canada and Denmark during 2000-2008. Incidence rates were age- and gender- standardized to the European Union 27-country 2007 population. During 83 million person-years of surveillance, 18,430 episodes of S. aureus BSI were identified. The overall annual incidence rate for S. aureus BSI was 26.1 per 100,000 population, and this was 24.2 and 1.9 per 100,000 for methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus, respectively. Although the overall incidence of community onset MSSA disease (15.0 per 100,000) was relatively similar across regions, rates of hospital onset MSSA (9.2 per 100,000), community onset MRSA (1.0 per 100,000), and hospital onset MRSA (0.8 per 100,000) varied substantially. While the overall rate of S. aureus BSI did not increase over the study period, there was an increase in the incidence of MRSA. Major changes in the occurrence of community- and hospital-onset MSSA and MRSA BSI occurred but these varied significantly among regions even within the same country. Although major changes in the epidemiology of community- and hospital onset MSSA and MRSA infections are occurring, this multi-national population-based study did not find that the overall incidence of S. aureus BSI is increasing.

Predictors of Mortality in Staphylococcus aureus Bacteremia

Predictors of Mortality in Staphylococcus aureus Bacteremia.

The most consistent predictor of mortality is age, with older patients being twice as likely to die. Except for the presence of comorbidities, the impacts of other host factors, including gender, ethnicity, socioeconomic status, and immune status, are unclear. Pathogen-host interactions, especially the presence of shock and the source of SAB, are strong predictors of outcomes. Although antibiotic resistance may be associated with increased mortality, questions remain as to whether this reflects pathogen-specific factors or poorer responses to antibiotic therapy, namely, vancomycin.

Less than 100 MRSA bloodstream infections in single month in UK for first time

News and Comment for the Pharmaceutical Industry : PharmiWeb.com.

According to the UK's Department of Health, MRSA bloodstream infections in the NHS have reached record low levels with fewer than 100 infections recorded in a single month for the first time. Reacting to the figures, Secretary of State for Health Andrew Lansley said: “I have been calling for a zero-tolerance approach to avoidable healthcare associated infections since 2004. Now, just over one year into the coalition government, MRSA bloodstream infections in the NHS are at their lowest level since records began with fewer than 100 infections in a single month for the first time.

Increased Active Surveillance May Explain Higher Prevalence of MRSA since 2006

Increased Active Surveillance May Explain Higher Prevalence of MRSA since 2006 | Quality.

A survey of MRSA colonization at 590 healthcare facilities revealed an increased prevalence of the multidrug-resistant organism, though researchers say the increase may be attributed to increasingly active surveillance, according to a study published in the American Journal of Infection Control. For their study, researchers distributed a survey to members of the Association for Professionals in Infection Control and Epidemiology. Members at 590 healthcare facilities returned the surveys, which revealed the following key points:  • Members reported 4,476 MRSA-colonized/infected patients between August 2010 through December 2010, indicating an overall MRSA prevalence rate of 66.4 per 1,000 inpatients. • A majority (75.7 percent) of respondents conducted active surveillance testing for MRSA. • Most MRSA-colonized/infected patients were detected within 48 hours of admission, with the most common site of infection being skin and soft tissue. The researchers noted although MRSA prevalence since 2006 has increased, more healthcare facilities are performance active surveillance and rates of healthcare-associated MRSA have decreased.

Scottish MRSA rate at 'lowest levels since records began'

Scottish MRSA rate at 'lowest levels since records began' | Nursing in Practice.

MRSA and MSSA infections are at their lowest levels in Scotland since records began in 2005, official figures suggest. Statistics from Health Protection Scotland shows MRSA (meticillin-resistant Staphylococcus aureus) cases decreased from 73 to 48 (34.3%) during the past year, with a 7.7% reduction during April and June alone.

MRSA infection falling in Ireland but still high

Rate of MRSA infection now at its lowest level - Health News, Health - Independent.ie.

The latest figures are for the first half of 2011 but they show that there were 140 cases reported compared to 177 for the same period in 2010. These numbers are only a proportion of the people who have MRSA in their bloodstream but they are a good measure of how much of a threat the infection is. The rate of MRSA infection in Irish hospitals fell to its lowest level in 2010. Bloodstream infections with MRSA dropped to 304 and contrasted with 2006 when 592 cases were recorded. Despite this drop in numbers, figures for Ireland are still relatively high and compare with the UK and southern European countries.

Untreatable MRSA in Greece?

AllAboutFeed - Weblog: Antibiotics lead us into death.

In most countries the situation is still manageable, but has already become critical in Greece and Turkey where it is almost impossible to treat infected patients with antibiotics that work. In Greece a MRSA-type has emerged that is resistant to all antibiotics. The situation is also critical because no new antibiotics are to be expected in the short term.

New MRSA strains are not directly descended from old ones: Study

New MRSA strains are not directly descended from old ones: Study.

By now, however, many bacteria found in hospitals and elsewhere have become resistant to methicillin, and scientists have suspected that these deadly modern MRSA strains descended directly from the 1950s strains. However the bugs' DNA tells a different story. Kreiswirth, Frank DeLeo, PhD, of the National Institute of Allergy and Infectious Diseases and colleagues compared the DNA in a total of 284 old and new S. aureus strains and found that the newer strains are not directly descended from the older ones but rather that all evolved from a common ancestor. Present day MRSA strains had DNA mutations that rendered them less deadly but more adept at infecting the nasal passages, mutations that were not present in the 1950s strains

MRSA diversity in Italy

Molecular epidemiology of meticillin-resistant Staphylococcus aureus in Italian cystic fibrosis patients: A national overview.

One hundred and seventy-eight strains isolated from 2360 patients attending the participating centres were analysed. We detected 56 (31.4%) SCCmec IV PVL-negative strains, with a resistance rate of 80.3% to clindamycin and of 14.5% to trimethoprim/sulphamethoxazole. MLST analysis showed that many isolates belonged to known epidemic lineages. The largest clone grouping of 29 isolates from 6 centres had the genetic background (ST8-MRSA-IV) of the American lineages USA300 and USA500, thus demonstrating the diffusion of these strains in a population considered at risk for hospital associated infections. Conclusions Known MRSA epidemic clones such as USA600, USA800, USA1100, and UK EMRSA-3 were described for the first time in Italy. The diffusion of MRSA strains with high pathogenic potential in the CF population suggests that analysis of the MRSA strains involved in pulmonary infections of these patients is needed.

Study: MRSA Outbreak in One Hospital May Affect Other Facilities in the Same Region

Study: MRSA Outbreak in One Hospital May Affect Other Facilities in the Same Region.

A MRSA outbreak at one hospital could lead to infection outbreaks at other hospitals in the same region, according to research published in Infection Control and Hospital Epidemiology. For their study, researchers conducted simulated MRSA outbreaks in various healthcare settings. Results from their research showed every simulated outbreak eventually affected other hospitals in the same network. The impact depended on outbreak size and location. Specifically, increasing MRSA prevalence at a single hospital (from 5 percent to 15 percent) led to a 2.9 percent average increase in relative prevalence at all other hospitals in the region, ranging from no effect to 46.4 percent. Similar results were found for MRSA outbreaks stemming from hospital intensive care units. Read the study about MRSA.

Clinical significance of staphylococcus aureus bacteriuria in a nationwide study of adults with s. Aureus bacteraemia

Clinical significance of staphylococcus aureus bacteriuria in a nationwide study of adults with s. Aureus bacteraemia.

Objectives To evaluate the clinical significance of Staphylococcus aureus bacteriuria (SABU) in adults with S. aureus bacteraemia (SAB). Methods All individuals ≥18 years old diagnosed with SAB in Iceland between December 1st 2003 and November 30th 2008 were retrospectively identified. Data was collected from medical records. Concomitant SABU was defined as growth of S. aureus in a urine sample taken within 24 hours of the index blood culture. Results SABU was seen in 27 of 166 (16.3%) SAB patients having urine cultured before administration of antibiotics, but after excluding those with SAB of urinary tract origin SABU was seen in 16 of 152 (10.5%). In this latter cohort SABU was independently associated with having endocarditis (RR 6.68; 95%CI 1.53-17.3) and admission to intensive-care unit (RR 2.84; 95%CI 1.25-4.44), while for having complicated SAB the RR was 1.56 (95%CI 0.96-1.80). No correlation was seen with mortality or relapse rates. Conclusions SABU appears to be secondary to SAB in some cases while it is the primary infection causing SAB in others. In patients with SAB of non-urinary tract origin SABU should probably be regarded as distant haematogenous seeding and a marker of deep tissue dissemination, thus affecting general management and treatment duration.

Getting quick answers about MRSA strains in a hospital

SmaI Restriction Site-Based Multiplex PCR for Typing of Hospital- and Community-Acquired Staphylococcus aureus -- Al-Zahrani et al. 49 (11): 3820 -- Journal of Clinical Microbiology.

In this study, we report the development of a typing technique for S. aureus, based on single-nucleotide polymorphism (SNP) variations in and around SmaI-restriction sites (CCCGGG). An assessment of the SmaI restriction site-based multiplex PCR (SmaI-multiplex PCR) typing (SMT) with respect to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) revealed a high level of concordance in the clustering of the test strains. The SmaI-multiplex PCR was found to be more discriminatory than MLST/staphylococcal cassette chromosome mec (SCCmec) typing but less discriminatory than PFGE. SMT can provide real-time information for the investigation of ongoing S. aureus hospital outbreaks. SMT meets the criteria of a practical typing method: it is simple, reproducible, and highly discriminatory and does not require expensive equipment or specialist expertise. Consequently, SmaI-multiplex PCR has the potential to be used in routine clinical microbiology laboratories.

MRSA ST239 dominates in Iran

Epidemic Methicillin-Susceptible Staphylococcus aureus Lineages Are the Main Cause of Infections at an Iranian University Hospital -- Havaei et al. 49 (11): 3990 -- Journal of Clinical Microbiology.

The majority of Staphylococcus aureus infections from Isfahan, Iran, were caused by epidemic methicillin-susceptible S. aureus (MSSA) lineages, sequence type 8 (ST8), ST22, ST30, and ST6. The predominant methicillin-resistant S. aureus strain was ST239. We observed a high prevalence of Panton-Valentine leukocidin-positive MSSA strains (19.7%), which is a matter of considerable concern, since these strains have the ability to cause severe infections.

Fuel nozzle handles a breeding ground for MRSA

Fuel nozzle handles a breeding ground for bacteria and viruses, says expert | Herald Sun.

FUELLING your car could be making you sick - and not because of the expense. A cleaning products manufacturer says fuel nozzle handles are fertile breeding grounds for bacteria and viruses - worse than mailboxes, escalator rails, parking meters and traffic light pedestrian buttons. Infectious diseases expert Flavia Huygens, an associate professor at the Queensland University of Technology, warned fuel pump handles could harbour a dangerous superbug, the methicillin-resistant staphylococcus aureus (MRSA). "Another study in Japan on public transport in trains isolated and identified MRSA. It's pretty dangerous because it's highly resistant to antibiotic therapy," she said. Ms Huygens said the bug could lurk in public areas that people touched: "It's highly likely with fuel pumps, because this superbug is transmitted by skin contact and hand-to-mouth contact."  Motorists are advised to wash their hands after using a fuel pump.