MRSA Infection

An algorithm based on one or two nasal samples is accurate to identify persistent nasal carriers of Staphylococcus aureus

An algorithm based on one or two nasal samples is accurate to identify persistent nasal carriers of Staphylococcus aureus - Verhoeven - 2011 - Clinical Microbiology and Infection - Wiley Online Library.

Persistent Staphylococcus aureus nasal carriers are at high risk of S. aureus infection. The present study delineates a simple strategy aimed at identifying rapidly and accurately this subset of subjects for clinical or epidemiological purposes. Ninety healthy volunteers were each identified as persistent, intermittent or non-nasal carriers of S. aureus by using seven specimens sampled over a 5-week period. By reference to this so-called reference standard, six other strategies aimed at simplifying and speeding the identification of persistent carriers and based on the qualitative or quantitative detection of S. aureus in one to three nasal samples were evaluated by the measure of the area under the curve of receiver operating characteristic diagrams. Among strategies using qualitative results, there was no statistical difference between protocols using seven and three samples. A threshold of 103 CFU of S. aureus per swab was found capable of defining persistent nasal carriage with a sensitivity of 83.1% and a specificity of 95.6%. These figures reached 95.5% and 94.9%, respectively, by using an algorithm including one or two nasal specimens according to the threshold of 103 CFU of S. aureus in the first swab. The latter two strategies were shown to be costly equivalents. The proposed algorithm-based strategy proved to be relevant to identify properly and consistently persistent nasal carriers of S. aureus. However, as it was built from data of healthy volunteers, it needs to be confirmed prospectively on patients potentially at risk for S. aureus infection.

Staphylococcus aureus determinants for nasal colonization

Trends in Microbiology - Staphylococcus aureus determinants for nasal colonization.

SummaryApproximately 20% of the healthy human population is persistently colonized in the nasal cavity with Staphylococcus aureus, which constitutes a major risk for infection. S. aureus seems to predominantly colonize the anterior part of the nasal cavity by adhering to nasal surface structures and escaping the host innate and adaptive immune responses. Several bacterial and host factors that play a role in these processes have been identified in the past few years and were in part functionally evaluated in appropriate colonization models.

 

Carriage of MRSA on Admission to European Rehabilitation Centers

Carriage of Methicillin Resistant Staphylococcus aureus on Admission to European Rehabilitation Centers – A Prospective Study - Bilavsky - Clinical Microbiology and Infection - Wiley Online Library.

Results:  A total of 1204 patients were studied. Among them, 105 (8.7%) had a positive admission MRSA screening result. MRSA carriers were more likely to be males, to have had a recent stay in another long term care facility or >2 weeks acute care hospital stay, prior history of colonization with MRSA, reduced level of consciousness, peripheral vascular disease and pressure sores. In multivariable logistic regression male gender (OR=2.2, 95%CI: 1.4-3.6, P=0.001), history of MRSA positivity (OR=6.8, 95%CI: 3.8-12.3, P<0.001), peripheral vascular disease (OR=2.5, 95%CI: 1.2-5, P=0.013), recent stay in another long term care facility (OR=2.1, 95%CI: 1.3-3.5, P=0.004), or long (>2 weeks) acute care hospital stay (OR=1.9, 95%CI: 1.2-3, P=0.004), remained significant risk factors for MRSA carriage. Conclusion:  MRSA carriage is common on admission to rehabilitation centers; less so, however, than previously described in long-term care facilities. Male gender, history of MRSA positivity, prior hospitalization and peripheral vascular disease may predict MRSA carriage, and may serve as indicators for using preemptive infection control measures.

3% of population colonized with MRSA?

National prevalence of methicillin-resistant Staphylococcus aureus in inpatients at United States health care facilities, 2010.

Personnel at 590 facilities indicated a state and responded to the survey. All states were represented, except for Alaska and Washington, DC (mean, 12 facilities per state; range, 1-38). Respondents reported 4,476 MRSA-colonized/infected patients in 67,412 inpatients; the overall MRSA prevalence rate was 66.4 per 1,000 inpatients (25.3 infections and 41.1 colonizations per 1,000 inpatients). Active surveillance testing was conducted by 75.7% of the respondents; 39.6% used nonselective media, 37.2% used selective media, and 23.3% used polymerase chain reaction. Detailed data were provided on 3,176 MRSA-colonized/infected patients. Of those in whom colonization/infection status was reported (1,908/3,086 [61.8%] were MRSA colonized and 1,778/3,086 [38.2%] were MRSA infected), most MRSA-colonized or infected patients (78.3%) were detected within 48 hours of admission; the most common site of infection was skin and soft tissue (42.9%); and, using the Centers for Disease Control and Prevention’s definitions, approximately 50% would be classified as health care-associated infections. Conclusion Our survey documents that the MRSA prevalence in 2010 is higher than that reported in our 2006 survey. However, the majority of facilities currently are performing active surveillance testing, and, compared with 2006, the rate of MRSA infection has decreased while the rate of MRSA colonization has increased. In addition, compared with 2006, the proportion of MRSA strains recovered from MRSA-colonized/infected patients that are health care-associated strains has deceased, and community-associated strains have increased.

What Increases the Risk for Persistent MRSA After Decolonization?

What Increases the Risk for Persistent MRSA After Decolonization?.

They found that low-level mupirocin resistance was significantly more common in patients with persistent colonization after therapy, occurring in 49 out of 75 (64%) case patients vs 26 of 75 (38%) controls. Similarly, chlorhexidine phenotypic resistance, which was more common overall, was significantly higher in case patients than controls, occurring in 68 of 75 (91%) vs. 51 of 75 (68%). Both of these were significant (P = .001). Furthermore, both low-level mupirocin resistance and chlorhexidine phenotypic resistance were present in all but one isolate. When they conducted multivariate analysis, controlling for a number of risk factors, the presence of low-level mupirocin resistance or chlorhexidine phenotypic resistance remained significantly associated with persistence of MRSA carriage. This is an important study because it suggests that institutions that are using mupirocin and chlorhexidine for decolonization of MRSA patients should be monitoring both the risk for persistent colonization and the presence of either low-level mupirocin or phenotypic chlorhexidine resistance. Given that these MRSA eradication programs are becoming much more widespread, such monitoring becomes critical.

Decolonizing Carriers Can Prevent Recurrrent CA-MRSA Infections

Decolonizing Carriers Can Prevent Recurrrent CA-MRSA Infections, Researchers Say.

Yaseen Rafee, of the Division of Infectious Diseases at the Children’s Hospital of Michigan in Detroit, and colleagues, sought to measure methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in household contacts of children with current community associated (CA)-MRSA infections (study group) in comparison with a group of household contacts of children without suspected Staphylococcus aureus infection (a control group). Cultures of the anterior nares were taken, and relatedness of isolated strains was tested using pulse field gel electrophoresis (PFGE). The researchers found that prevalence of MRSA colonization in the study group was significantly higher than in the control group (18/77 (23 percent) vs 3/77 (3.9 percent); p [less than or equal to] 0.001). The prevalence of SA colonization was 28/77 (36 percent) in the study group and 16/77 (21 percent) in the control group (p = 0.032). The prevalence of SA nasal colonization among patients was 6/24 (25 percent); one with methicillin-susceptible S. aureus (MSSA) and five with MRSA. In the study (patient) group, 14/24 (58 percent) families had at least one household member who was colonized with MRSA compared to 2/29 (6.9 percent) in the control group (p = 0.001). Of 69 total isolates tested by PFGE, 40 (58 percent) were related to USA300. Panton-Valetine leukocidin (PVL) genes were detected in 30/52 (58 percent) tested isolates. Among the families with [greater than or equal to] one contact colonized with MRSA, similar PFGE profiles were found between the index patient and a contact in 10/14 families. The researchers conclude that prevalence of asymptomatic nasal carriage of MRSA is higher among household contacts of patients with CA-MRSA disease than control group. Decolonizing such carriers may help prevent recurrent CA-MRSA infections. Their research was published in BMC Infectious Diseases.

Man who contracted MRSA in 2001 says he fears passing infection to members of family

Health News: Man who contracted MRSA in 2001 says he fears passing infection to members of family | West End Extra.

AN accountant says he has cut himself off from some of his closest fam­ily for more than 10 years because he is worried about infecting them with MRSA. Patrick Burgess, who lives in Somers Town, was put in an isolation ward after he contracted the “superbug” in the Royal Free Hospital in 2001. The 68-year-old was discharged four months later, after a serious operation, but a test last month found he was still carrying the bacteria. He claims he has had contradictory advice from health experts – including his GP – and has begun to believe the MRSA scare was “all a big con”.

Past MRSA and Hospital Treatment - What works best?

Should the methicillin-resistant Staphylococcus aureus carriage status be used as a guide to treatment for skin and soft tissue infections?.

A total of 378 skin and soft tissue infections in 346 patients were retrieved. Overall cure was achieved in 330 episodes (87%) after a median antibiotic administration of 15 days. Among all episodes, 102 revealed a positive current MRSA status (during 2 weeks preceding infection; 27%) and 70 (19%) were MRSA carriers in the past. Sensitivity, specificity, positive and negative predictive values of current MRSA skin carriage to predict abscesses due to MRSA were 0.68, 0.77, 0.19, and 0.97, respectively. Fifty-four current MRSA carriers (54/102, 53%) and 30 past carriers (43%) were successfully treated with a non-MRSA antibiotic agent. In multivariate Cox regression analysis, anti-MRSA coverage (hazard ratio 1.2, 95%CI 0.5-2.8) and duration of antibiotic therapy (HR 1.0, 95%CI 0.96-1.02) did not influence treatment failure among patients with positive MRSA carriage. Conclusions Current or past HA-MRSA skin carriage poorly predicts the need for anti-MRSA coverage for the antibiotic treatment of skin and soft tissue infections in hospitalized orthopaedic patients.

Chronic MRSA and Family Pets

Sleeping With The Enemy: What You Get From Your Pet | Wired Science | Wired.com.

“A 48-year-old man with diabetes and his wife had recurrent MRSA infections. Culture of nares samples from the family dog grew mupirocin-resistant MRSA that had a PFGE chromosomal pattern identical to the MRSA isolated from the patient’s nares and his wife’s wound. The couple reported that the dog routinely slept in their bed and frequently licked their faces….

Jury out on decolonization of MRSA?

Controversies in Hospital Infection Prevention.

In the December 2011 Lancet ID, Andrew Simor from the University of Toronto reviewed articles listed in PubMed from 1989-2010 assessing the benefits of S. aureus decolonization. There were no surprising results. In fact, most of the conclusions were hedged. For example he says that "some data support the use of decolonisation in surgical patients colonised with S aureus, particularly in those undergoing cardiothoracic procedures" and "patients undergoing chronic haemodialysis or peritoneal dialysis might benefit from decolonisation, although repeated courses of treatment are needed, and the effects are modest."

Wounds, Functional Disability, and Indwelling Devices Are Associated With Cocolonization by MRSA

Wounds, Functional Disability, and Indwelling Devices Are Associated With Cocolonization by Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococci in Southeast Michigan.

Background. Methicillin-resistant Staphylococcus aureus (MRSA) remains sensitive to vancomycin; when vancomycin-resistant S. aureus (VRSA) emerges, treatment becomes more complex. VRSA emergence is attributed to conjugative transfer of the vancomycin-resistance gene cluster from vancomycin-resistant enterococci (VRE) to MRSA. Because cocolonization with MRSA and VRE precedes VRSA development, this study investigates the epidemiology of cocolonization in skilled nursing facility (SNF) residents at high risk for MRSA or VRE colonization.  Results. The incidence of MRSA/VRE cocolonization among residents with indwelling devices was 6.5 per 100 resident-months; 5.2 (95% confidence interval [CI]: 1.49–18.1) times that among those without devices. MRSA/VRE cocolonization in the device group occurred most frequently in wounds (4.1 per 100 resident-months). In a logistic regression analysis limited to residents with devices, functional disability (rate ratio [RR], 1.3; 95% CI: 1.1–1.4) and wound presence (RR, 3.4; 95% CI: 1.4–8.6) were independent risk factors of cocolonization. Conclusions. In a population of SNF residents, individuals with indwelling devices who also had functional disability or wounds were at greatest risk of MRSA/VRE cocolonization. These individuals should be routinely monitored for the presence of VRSA colonization.

MRSA antibiotic-associated diarrhea link on the rise

Data on MRSA, antibiotic-associated diarrhea link on the rise.

Results indicated 2,064 patients had C. difficile-associated diarrhea (2.6 cases/1,000 patient-days) and 1,597 had MRSA recovered from the stool. Of which, 786 patients had heavy growth of MRSA in stool and 33 were classified as MRSA-associated antibiotic-associated diarrhea. “In most patients who have stool specimens positive for MRSA, this represents colonization of the gastrointestinal tract, and therapy is not warranted,” Boyce said. “However, in patients with antibiotic-associated diarrhea, negative stool assays for C. difficile, no other identified enteric pathogen and no evidence that diarrhea is related to medications, MRSA should be considered a possible cause of the diarrhea. In such circumstances, a gram stain of stool showing many gram-positive cocci with morphology consistent with S. aureus and little or no normal flora, and heavy (nearly pure) growth of MRSA in stool specimens are suggestive of antibiotic-associated diarrhea due to MRSA. Oral vancomycin is generally considered the drug of choice for such infections.” – by Ashley DeNyse

MRSA Colonization Ups Future Infection Risk in Children

MRSA Colonization Ups Future Infection Risk in Children --Doctors Lounge.

Aaron M. Milstone, M.D., from the Johns Hopkins University School of Medicine in Baltimore, and colleagues measured the risk of developing a subsequent MRSA infection in 3,140 children with MRSA colonization who were admitted to a pediatric intensive care unit between 2007 and 2010.  The investigators found that the MRSA admission prevalence was 4.9 percent. A total of 56 children (1.8 percent) developed an MRSA infection, including 13 and 43 children who were colonized and not colonized on admission, respectively (8.5 and 1.4 percent, respectively; relative risk [RR], 5.9). MRSA infection developed during hospitalization in 10 (0.3 percent) of these children, including three of the 153 children colonized on admission, and seven of the 2,987 children not colonized on admission (1.9 and 0.2 percent, respectively; RR, 8.4). Subsequent infections were more likely in African-Americans, and those with public health insurance. A total of 15 children acquired MRSA colonization in the pediatric intensive care unit, and seven developed a subsequent MRSA infection.

Hospitalized Children Who Carry MRSA at Risk for Full-Blown Infections

Health News - Hospitalized Children Who Carry MRSA at Risk for Full-Blown Infections.

A Johns Hopkins Children’s Center study of more than 3,000 hospitalized children shows that those colonized but not sick with the antibiotic-resistant bacterium MRSA are at considerable risk for developing full-blown infections.  The study involved 3,140 children admitted to the Hopkins Children’s pediatric intensive care unit (PICU) between 2007 and 2010. Routine screening showed that 153 arrived at the hospital already colonized with MRSA. Compared with noncarriers, these patients were were nearly six times more likely to develop invasive MRSA infections after discharge and eight times more likely to develop them while still hospitalized.

More detail at the link above

Dutch guidelines for decolonization of MRSA

National guidelines for decolonization of methicillin-resistant Staphylococcus aureus carriers: the implications of recent experience in the Netherlands.

Screening of patients for carriage of methicillin-resistant Staphylococcus aureus (MRSA) coupled with interventions such as contact isolation is widely regarded as a means of reducing rates of MRSA infection and inter-patient transmission. Recent studies in the Netherlands have shown that introduction of a national guideline in which uncomplicated carriage is treated with mupirocin nasal ointment and chlorhexidine soap solution, and complicated carriage is treated using the same regimen supplemented with two oral antibiotics, was successful, with up to 80% of patients being decolonized. Increased success was seen in patients, particularly those with complicated carriage, whose treatment adhered closely to the guideline. As the Netherlands has a low level of MRSA, further work is required to see if this regimen will be as effective at reducing carriage in countries with higher rates of endemic MRSA, where re-colonization may be expected to occur more often.

Rectal Colonization Driving Staph Skin Epidemic

Importance of Colonization Site in the Current Epidemic of Staphylococcal Skin Abscesses.

S aureus was detected significantly more often in the rectum of children with abscesses (47%) compared with those in the control group (1%; P = .0001). Rates of nasal colonization with S aureus were equivalent for children with abscesses (27%) and control subjects (20%; P = .33). S aureus recovered from the rectum was identical to S aureus in the abscess in 88% of cases, compared with 75% of nasal isolates. PFT USA300, staphylococcal cassette chromosome mec type IV, and Panton-Valentine leukocidin genes were significantly increased in the S aureus isolates from children with abscesses compared with those from control subjects. CONCLUSIONS: Skin and soft-tissue abscesses in the current epidemic of community-associated staphylococcal disease are strongly associated with rectal colonization by PFT USA300. Nasal colonization in children does not seem to be a risk factor.

MRSA carriage and postoperative infection

Preoperative carriage and postoperative same-species sternal wound infection after cardiac surgery -- Maillet et al., 10.1510/icvts.2011.275362 -- Interactive CardioVascular and Thoracic Surgery.

All patients referred for elective cardiac surgery were screened using multisite (nares, axillae, rectal) sampling at admission to detect MSSA, MRSA, and MDRGNB. Of the 1895 patients addressed, 425 patients (22.4%) were colonized at admission. Preoperative carriers more frequently developed SWI than non-carriers, respectively, 11% vs. 5.5% (P<0.05). Because of the small sample, MDRGNB carriers could not be analyzed. For prediction of MSSA SWI with preoperative MSSA carriage, the area under the receiver operating characteristic (ROC) curve was 0.720 (95% confidence interval (CI), 0.364-0.796) and 0.710 (95% CI, 0.623-0.787) for prediction of MRSA SWI with preoperative MRSA carriage. Preoperative MSSA carriage is frequent but preoperative MRSA or MDRGNB carriage remains infrequent. The ability of preoperative carriage to predict a same-pathogen-postoperative SWI was low and should not be used to guide empirical antibiotherapy

Hot Tea and Coffee May Lower MRSA Risk

Hot Tea and Coffee May Lower MRSA Risk.

Overall, 1.4% of the sample had MRSA nasal carriage. An estimated 88.6 million people (48.6% of the population) reported consuming hot tea in the past month. An estimated 110.7 million people (60.8%) reported consuming coffee. Those who consumed hot tea had less than half the likelihood of having MRSA nasal carriage compared with those who did not consume hot tea (odds ratio, 0.47; 95% confidence interval, 0.31 - 0.70).  The mechanisms behind the seemingly protective effect of coffee and tea are not completely understood, but both these beverages appear to have antimicrobial properties. In the case of coffee, trigonelline, glyoxal, methylglyoxal, and diacetyl may have such an effect. For tea, attention has focused on tannic acid and catechins. Both beverages decrease iron absorption, which may be important because iron is critical for growth of S aureus, said the authors.  There are other possible variables that may have reduced MRSA nasal carriage risk that were not looked at in the study, said Dr. Glatt. "I have no idea if it's the coffee that does this or some factor related to the coffee, but maybe people who drink coffee also wash their hands more frequently because they have access to a sink to pour their coffee out." It is too early to recommend changes in hot tea and coffee drinking habits, added Dr. Glatt.

Flocked Swabs v Fiber Swabs when researching MRSA nasal carriage?

Comparison of Automated Processing of Flocked Swabs with Manual Processing of Fiber Swabs for Detection of Nasal Carriage of Staphylococcus aureus -- Jones et al. 49 (7): 2717 -- Journal of Clinical Microbiology.

The sensitivity of automated culture of Staphylococcus aureus from flocked swabs versus that of manual culture of fiber swabs was prospectively compared using nasal swabs from 867 patients. Automated culture from flocked swabs significantly increased the detection rate, by 13.1% for direct culture and 10.2% for enrichment culture.

Why MRSA decolonization sometimes fails

Eradication of carriage with methicillin-resistant Staphylococcus aureus: determinants of treatment failure.

Methods A multivariate logistic regression model was performed with subgroup analyses for uncomplicated and complicated MRSA carriage (the latter including MRSA infection, skin lesions, foreign-body material, mupirocin resistance and/or exclusive extranasal carriage) and for those treated according to the guideline (i.e. mupirocin nasal ointment and chlorhexidine soap solution for uncomplicated carriage, in combination with two oral antibiotics for complicated carriage). Results Six hundred and thirteen MRSA carriers were included, of whom 333 (54%) had complicated carriage; 327 of 530 patients (62%) with known complexity of carriage were treated according to the guideline with an absolute increase in treatment success of 20% (95% confidence interval 12%–28%). Among those with uncomplicated carriage, guideline adherence [adjusted odds ratio (ORa) 7.4 (1.7–31.7)], chronic pulmonary disease [ORa 44 (2.9–668)], throat carriage [ORa 2.9 (1.4–6.1)], perineal carriage [ORa 2.2 (1.1–4.4)] and carriage among household contacts [ORa 5.6 (1.2–26)] were associated with treatment failure. Among those with complicated carriage, guideline adherence was associated with treatment success [ORa 0.2 (0.1–0.3)], whereas throat carriage [ORa 4.4 (2.3–8.3)] and dependence in activities of daily living [ORa 3.6 (1.4–8.9)] were associated with failure. Conclusions Guideline adherence, especially among those with complicated MRSA carriage, was associated with treatment success. Adding patients with extranasal carriage or dependence in daily self-care activities to the definition of complicated carriage, and treating them likewise, may further increase treatment success.