Chlorhexidine and Mupirocin for Clearance of Methicillin-Resistant Staphylococcus aureus Colonization After Hospital Discharge: A Secondary Analysis of the Changing Lives by Eradicating Antibiotic Resistance Trial.

BACKGROUND: The CLEAR Trial demonstrated that a multisite body decolonization regimen reduced post-discharge infection and hospitalization in methicillin-resistant Staphylococcus aureus (MRSA) carriers. Here, we describe decolonization efficacy. METHODS: We performed a large, multicenter, randomized clinical trial of MRSA decolonization among adult patients after hospital discharge with MRSA infection or colonization. Participants were randomized 1:1 to either MRSA prevention education or education plus decolonization with topical chlorhexidine, oral chlorhexidine, and nasal mupirocin. Participants were swabbed in the nares, throat, axilla/groin, and wound (if applicable) at baseline and 1, 3, 6, and 9 months after randomization. The primary outcomes of this study are follow-up colonization differences between groups. RESULTS: Among 2121 participants, 1058 were randomized to decolonization. By 1 month, MRSA colonization was lower in the decolonization group compared with the education-only group (odds ration [OR] = 0.44; 95% confidence interval [CI], .36-.54; P ≤ .001). A similar magnitude of reduction was seen in the nares (OR = 0.34; 95% CI, .27-.42; P < .001), throat (OR = 0.55; 95% CI, .42-.73; P < .001), and axilla/groin (OR = 0.57; 95% CI, .43-.75; P < .001). These differences persisted through month 9 except at the wound site, which had a relatively small sample size. Higher regimen adherence was associated with lower MRSA colonization (P ≤ .01). CONCLUSIONS: In a randomized, clinical trial, a repeated post-discharge decolonization regimen for MRSA carriers reduced MRSA colonization overall and at multiple body sites. Higher treatment adherence was associated with greater reductions in MRSA colonization.

Decolonization to Reduce Postdischarge Infection Risk among MRSA Carriers.

BACKGROUND: Hospitalized patients who are colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at high risk for infection after discharge. METHODS: We conducted a multicenter, randomized, controlled trial of postdischarge hygiene education, as compared with education plus decolonization, in patients colonized with MRSA (carriers). Decolonization involved chlorhexidine mouthwash, baths or showers with chlorhexidine, and nasal mupirocin for 5 days twice per month for 6 months. Participants were followed for 1 year. The primary outcome was MRSA infection as defined according to Centers for Disease Control and Prevention (CDC) criteria. Secondary outcomes included MRSA infection determined on the basis of clinical judgment, infection from any cause, and infection-related hospitalization. All analyses were performed with the use of proportional-hazards models in the per-protocol population (all participants who underwent randomization, met the inclusion criteria, and survived beyond the recruitment hospitalization) and as-treated population (participants stratified according to adherence). RESULTS: In the per-protocol population, MRSA infection occurred in 98 of 1063 participants (9.2%) in the education group and in 67 of 1058 (6.3%) in the decolonization group; 84.8% of the MRSA infections led to hospitalization. Infection from any cause occurred in 23.7% of the participants in the education group and 19.6% of those in the decolonization group; 85.8% of the infections led to hospitalization. The hazard of MRSA infection was significantly lower in the decolonization group than in the education group (hazard ratio, 0.70; 95% confidence interval [CI], 0.52 to 0.96; P=0.03; number needed to treat to prevent one infection, 30; 95% CI, 18 to 230); this lower hazard led to a lower risk of hospitalization due to MRSA infection (hazard ratio, 0.71; 95% CI, 0.51 to 0.99). The decolonization group had lower likelihoods of clinically judged infection from any cause (hazard ratio, 0.83; 95% CI, 0.70 to 0.99) and infection-related hospitalization (hazard ratio, 0.76; 95% CI, 0.62 to 0.93); treatment effects for secondary outcomes should be interpreted with caution owing to a lack of prespecified adjustment for multiple comparisons. In as-treated analyses, participants in the decolonization group who adhered fully to the regimen had 44% fewer MRSA infections than the education group (hazard ratio, 0.56; 95% CI, 0.36 to 0.86) and had 40% fewer infections from any cause (hazard ratio, 0.60; 95% CI, 0.46 to 0.78). Side effects (all mild) occurred in 4.2% of the participants. CONCLUSIONS: Postdischarge MRSA decolonization with chlorhexidine and mupirocin led to a 30% lower risk of MRSA infection than education alone. (Funded by the AHRQ Healthcare-Associated Infections Program and others; ClinicalTrials.gov number, NCT01209234 .).

A Placebo-Controlled Trial of Antibiotics for Smaller Skin Abscesses.

BACKGROUND: Uncomplicated skin abscesses are common, yet the appropriate management of the condition in the era of community-associated methicillin-resistant Staphylococcus aureus (MRSA) is unclear. METHODS: We conducted a multicenter, prospective, double-blind trial involving outpatient adults and children. Patients were stratified according to the presence of a surgically drainable abscess, abscess size, the number of sites of skin infection, and the presence of nonpurulent cellulitis. Participants with a skin abscess 5 cm or smaller in diameter were enrolled. After abscess incision and drainage, participants were randomly assigned to receive clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), or placebo for 10 days. The primary outcome was clinical cure 7 to 10 days after the end of treatment. RESULTS: We enrolled 786 participants: 505 (64.2%) were adults and 281 (35.8%) were children. A total of 448 (57.0%) of the participants were male. S. aureus was isolated from 527 participants (67.0%), and MRSA was isolated from 388 (49.4%). Ten days after therapy in the intention-to-treat population, the cure rate among participants in the clindamycin group was similar to that in the TMP-SMX group (221 of 266 participants [83.1%] and 215 of 263 participants [81.7%], respectively; P=0.73), and the cure rate in each active-treatment group was higher than that in the placebo group (177 of 257 participants [68.9%], P<0.001 for both comparisons). The results in the population of patients who could be evaluated were similar. This beneficial effect was restricted to participants with S. aureus infection. Among the participants who were initially cured, new infections at 1 month of follow-up were less common in the clindamycin group (15 of 221, 6.8%) than in the TMP-SMX group (29 of 215 [13.5%], P=0.03) or the placebo group (22 of 177 [12.4%], P=0.06). Adverse events were more frequent with clindamycin (58 of 265 [21.9%]) than with TMP-SMX (29 of 261 [11.1%]) or placebo (32 of 255 [12.5%]); all adverse events resolved without sequelae. One participant who received TMP-SMX had a hypersensitivity reaction. CONCLUSIONS: As compared with incision and drainage alone, clindamycin or TMP-SMX in conjunction with incision and drainage improves short-term outcomes in patients who have a simple abscess. This benefit must be weighed against the known side-effect profile of these antimicrobials. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00730028 .).

A Systematic Review and Meta-Analysis of the Data Behind Current Recommendations for Corticosteroids in Non-HIV-Related PCP: Knowing When You Are on Shaky Foundations.

BACKGROUND: Randomized trials show a mortality benefit to adjunctive corticosteroids for human immunodeficiency virus (HIV)-related Pneumocystis jiroveci pneumonia (HIV-PCP). Guidelines for non-HIV PCP (NH-PCP) recommend adjunctive corticosteroids based on expert opinion. We conducted a systematic review and meta-analysis characterizing adjunctive corticosteroids for NH-PCP. METHODS: We searched MEDLINE from 1966 through 2015. Data on clinical outcomes from NH-PCP were extracted with a standardized instrument. Heterogeneity was assessed with the I2 index. Pooled odds ratios and 95% confidence interval were calculated using a fixed effects model. RESULTS: Our search yielded 5044 abstracts, 277 articles were chosen for full review, and 6 articles described outcomes in moderate to severe NH-PCP. Studies were limited by variable definitions, treatment selection bias, concomitant infections and small sample size. Individual studies reported shorter intensive care unit stay and duration of mechanical ventilation of patients given adjunctive corticosteroids. There was no association between corticosteroids and survival in NH-PCP (odds ratio, 0.66; 95% confidence interval, 0.38-1.15; P = 0.14). CONCLUSIONS: The literature does not support an association between adjunctive corticosteroids and survival from NH-PCP but data are limited and findings should not be considered conclusive. Further research with improved methodology is needed to better understand the role of adjunctive corticosteroids for NH-PCP.

Relationship between Adherence to Oral Antibiotics and Postdischarge Clinical Outcomes among Patients Hospitalized with Staphylococcus aureus Skin Infections.

Skin and soft tissue infections are common and frequently recur. Poor adherence to antibiotic therapy may lead to suboptimal clinical outcomes. However, adherence to oral antibiotic therapy for skin and soft tissue infections and its relationship to clinical outcomes have not been examined. We enrolled adult patients hospitalized with uncomplicated skin and soft tissue infections caused by Staphylococcus aureus who were being discharged with oral antibiotics to complete therapy. We fit the participants' pill bottles with an electronic bottle cap that recorded each pill bottle opening, administered an in-person standardized questionnaire at enrollment, 14 days, and 30 days, and reviewed the participants' medical records to determine outcomes. Our primary outcome was poor clinical response, defined as a change in antibiotic therapy, new incision-and-drainage procedure, or new skin infection within 30 days of hospital discharge. Of our 188 participants, 87 had complete data available for analysis. Among these participants, 40 (46%) had a poor clinical response at 30 days. The mean electronically measured adherence to antibiotic therapy was significantly different than the self-reported adherence (57% versus 96%; P < 0.0001). In a multivariable model, poor clinical response at 30 days was associated with patients having lower adherence, being nondiabetic, and reporting a lack of illicit drug use within the previous 12 months (P < 0.05). In conclusion, we found that patient adherence to oral antibiotic therapy for a skin and soft tissue infection after hospital discharge was low (57%) and associated with poor clinical outcome. Patients commonly overstate their medication adherence, which may make identification of patients at risk for nonadherence and poor outcomes challenging. Further studies are needed to improve postdischarge antibiotic adherence after skin and soft tissue infections.

Treatment for Positive Urine Cultures in Hospitalized Adults: A Survey of Prevalence and Risk Factors in 3 Medical Centers.

BACKGROUND: Antibiotic treatment for asymptomatic bacteriuria (ASB) is prevalent but often contrary to published guidelines. OBJECTIVE: To evaluate risk factors for treatment of ASB. DESIGN: Retrospective observational study. SETTING: A tertiary academic hospital, county hospital, and community hospital. PATIENTS: Hospitalized adults with bacteriuria. METHODS: Patients without documented symptoms of urinary tract infection per Infectious Diseases Society of America (IDSA) criteria were classified as ASB. We examined ASB treatment risk factors as well as broad-spectrum antibiotic usage and quantified diagnostic concordance between IDSA and National Healthcare Safety Network criteria. RESULTS: Among 300 patients with bacteriuria, ASB was present in 71% by IDSA criteria. By National Healthcare Safety Network criteria, 71% of patients had ASB; within-patient diagnostic concordance with IDSA was moderate (kappa, 0.52). After excluding those given antibiotics for nonurinary indications, antibiotics were given to 38% (62/164) with ASB. Factors significantly associated with ASB treatment were elevated urine white cell count (65 vs 24 white blood cells per high-powered field, P<.01), hospital identity (hospital C vs A, odds ratio, 0.34 [95% CI, 0.14-0.80], P =.01), presence of leukocyte esterase (5.48 [2.35-12.79], P<.01), presence of nitrites (2.45 [1.11-5.41], P=.03), and Escherichia coli on culture (2.4 [1.2-4.7], P=.01). Of patients treated for ASB, broad-spectrum antibiotics were used in 84%. CONCLUSIONS: ASB treatment was prevalent across settings and contributed to broad-spectrum antibiotic use. Associating abnormal urinalysis results with the need for antibiotic treatment regardless of symptoms may drive unnecessary antibiotic use.

The association of patient complexities with antibiotic ordering.

BACKGROUND: Antibiotic treatment decisions for medically complex patients are complicated, as the risk of undertreatment may be severe, whereas overtreatment may be associated with adverse effects and the emergence of antibiotic resistant pathogens. OBJECTIVE: To determine the influence of patient complexities on providers' decisions to prescribe antibiotics in 3 common hospital-based clinical vignettes. DESIGN: A physician survey. SETTING: Three urban medical centers in Los Angeles County, California. PARTICIPANTS: Hospital-based physicians. MEASUREMENTS: Physicians were presented 3 clinical vignettes, with variations by patient age, comorbidity burden, functional status, and follow-up, and asked to choose the best antibiotic regimen. We described the association of additional patient complexity on the proportion of guideline-adherent antibiotic choices. RESULTS: In the survey, 28% to 49% of physicians recommended antibiotics that were inconsistent with national guidelines. This percentage increased to 48% to 63% for medically complex patients, defined as those with either older age, high medical comorbidity burden, poor functional status, or limited follow-up after hospital discharge (P < 0.01). CONCLUSIONS: In 3 vignettes depicting common clinical scenarios among hospitalized adults, inappropriate antibiotic use was prevalent and occurred more often for patients with medical complexities. Treatment guidelines should consider addressing medically complex patients in the context of infection management.

USA300 and USA500 clonal lineages of Staphylococcus aureus do not produce a capsular polysaccharide due to conserved mutations in the cap5 locus.

UNLABELLED: The surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed against Staphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistant S. aureus (MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptible S. aureus (MSSA) isolates were CP negative (CP(-)). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP(-). Whole-genome sequence analysis of 146 CP(-) USA300 MRSA isolates revealed they all carry a cap5 locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in the cap5 promoter, cap5D nucleotide 994, and cap5E nucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same four cap5 mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of the cap loci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specific cap5 mutations arose sequentially in S. aureus in a common ancestor of USA300 and USA500 isolates. IMPORTANCE: The USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP(-)) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP(+)) phenotype is unlikely in vivo or in vitro since it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP(-) and provide new insight into the evolution of the USA300 and USA500 lineages.

Transmission and microevolution of USA300 MRSA in U.S. households: evidence from whole-genome sequencing.

UNLABELLED: Methicillin-resistant Staphylococcus aureus (MRSA) USA300 is a successful S. aureus clone in the United States and a common cause of skin and soft tissue infections (SSTIs). We performed whole-genome sequencing (WGS) of 146 USA300 MRSA isolates from SSTIs and colonization cultures obtained from an investigation conducted from 2008 to 2010 in Chicago and Los Angeles households that included an index case with an S. aureus SSTI. Identifying unique single nucleotide polymorphisms (SNPs) and analyzing whole-genome phylogeny, we characterized isolates to understand transmission dynamics, genetic relatedness, and microevolution of USA300 MRSA within the households. We also compared the 146 USA300 MRSA isolates from our study with the previously published genome sequences of the USA300 MRSA isolates from San Diego (n = 35) and New York City (n = 277). We found little genetic variation within the USA300 MRSA household isolates from Los Angeles (mean number of SNPs ± standard deviation, 17.6 ± 35; π nucleotide diversity, 3.1 × 10(-5)) or from Chicago (mean number of SNPs ± standard deviation, 12 ± 19; π nucleotide diversity, 3.1 × 10(-5)). The isolates within a household clustered into closely related monophyletic groups, suggesting the introduction into and transmission within each household of a single common USA300 ancestral strain. From a Bayesian evolutionary reconstruction, we inferred that USA300 persisted within households for 2.33 to 8.35 years prior to sampling. We also noted that fluoroquinolone-resistant USA300 clones emerged around 1995 and were more widespread in Los Angeles and New York City than in Chicago. Our findings strongly suggest that unique USA300 MRSA isolates are transmitted within households that contain an individual with an SSTI. Decolonization of household members may be a critical component of prevention programs to control USA300 MRSA spread in the United States. IMPORTANCE: USA300, a virulent and easily transmissible strain of methicillin-resistant Staphylococcus aureus (MRSA), is the predominant community-associated MRSA clone in the United States. It most commonly causes skin infections but also causes necrotizing pneumonia and endocarditis. Strategies to limit the spread of MRSA in the community can only be effective if we understand the most common sources of transmission and the microevolutionary processes that provide a fitness advantage to MRSA. We performed a whole-genome sequence comparison of 146 USA300 MRSA isolates from Chicago and Los Angeles. We show that households represent a frequent site of transmission and a long-term reservoir of USA300 strains; individuals within households transmit the same USA300 strain among themselves. Our study also reveals that a large proportion of the USA300 isolates sequenced are resistant to fluoroquinolone antibiotics. The significance of this study is that if households serve as long-term reservoirs of USA300, household MRSA eradication programs may result in a uniquely effective control method.

Clindamycin versus trimethoprim-sulfamethoxazole for uncomplicated skin infections.

BACKGROUND: Skin and skin-structure infections are common in ambulatory settings. However, the efficacy of various antibiotic regimens in the era of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is unclear. METHODS: We enrolled outpatients with uncomplicated skin infections who had cellulitis, abscesses larger than 5 cm in diameter (smaller for younger children), or both. Patients were enrolled at four study sites. All abscesses underwent incision and drainage. Patients were randomly assigned in a 1:1 ratio to receive either clindamycin or trimethoprim-sulfamethoxazole (TMP-SMX) for 10 days. Patients and investigators were unaware of the treatment assignments and microbiologic test results. The primary outcome was clinical cure 7 to 10 days after the end of treatment. RESULTS: A total of 524 patients were enrolled (264 in the clindamycin group and 260 in the TMP-SMX group), including 155 children (29.6%). One hundred sixty patients (30.5%) had an abscess, 280 (53.4%) had cellulitis, and 82 (15.6%) had mixed infection, defined as at least one abscess lesion and one cellulitis lesion. S. aureus was isolated from the lesions of 217 patients (41.4%); the isolates in 167 (77.0%) of these patients were MRSA. The proportion of patients cured was similar in the two treatment groups in the intention-to-treat population (80.3% in the clindamycin group and 77.7% in the TMP-SMX group; difference, -2.6 percentage points; 95% confidence interval [CI], -10.2 to 4.9; P=0.52) and in the populations of patients who could be evaluated (466 patients; 89.5% in the clindamycin group and 88.2% in the TMP-SMX group; difference, -1.2 percentage points; 95% CI, -7.6 to 5.1; P=0.77). Cure rates did not differ significantly between the two treatments in the subgroups of children, adults, and patients with abscess versus cellulitis. The proportion of patients with adverse events was similar in the two groups. CONCLUSIONS: We found no significant difference between clindamycin and TMP-SMX, with respect to either efficacy or side-effect profile, for the treatment of uncomplicated skin infections, including both cellulitis and abscesses. (Funded by the National Institute of Allergy and Infectious Diseases and the National Center for Advancing Translational Sciences, National Institutes of Health; ClinicalTrials.gov number, NCT00730028.).

Body site Staphylococcus aureus colonization among maintenance hemodialysis patients.

BACKGROUND: Patients on maintenance hemodialysis therapy are at high risk for health care-associated infections. Staphylococcus aureus is a common cause of health care-associated infections among maintenance hemodialysis patients. It is established that S. aureus colonization is associated with an increased risk for subsequent infection in this population. There is an increasing number of reports that extranasal S. aureus colonization is more common than previously believed and in certain body sites even more common than nasal colonization. There are few data describing extranasal colonization among maintenance hemodialysis patients. METHODS: We surveyed 100 patients at 3 body sites (anterior nares, oropharynx, and inguinal region) for S. aureus colonization. Participants were also administered a standardized survey to assess risk factors for S. aureus colonization. RESULTS: We found that 42% (95% CI 32-52) of patients were S. aureus colonized in >1 body site. Extranasal colonization was found among 32% (95% CI 23-41). There were trends suggestive of an association between S. aureus colonization and younger age (OR 0.97, 95% CI 0.94-1.001, p = 0.06) and not having been hospitalized in the previous 12 months (OR 0.44, 95% CI 0.19-1.06, p = 0.14). CONCLUSION: Extranasal S. aureus colonization is common among maintenance hemodialysis patients with a prevalence of approximately one third. Future S. aureus decolonization efforts may need to consider not just nasal decolonization but also decolonization of the skin and oropharynx.

Tolerance of benznidazole in a United States Chagas Disease clinic.

The US-based Center of Excellence for Chagas Disease performed an observational study on the safety and tolerance of benznidazole 5 mg/kg/day for 60 days in 30 adults with chronic Chagas disease. The side-effect profile was suboptimal, including 5 cases of debilitating neuropathy and an unusually high angioedema rate.

Risk factors for central line-associated bloodstream infections in the era of prevention bundles.

Little is known about central line-associated bloodstream infection risk factors in the bundle era. In our case-control investigation, we found that independent risk factors for central line-associated bloodstream infection at our center included the number of recent lab tests, catheter duration, and lack of hemodynamic monitoring as the insertion indication. Infect Control Hosp Epidemiol 2014;00(0): 1-3.

Staphylococcus aureus skin infection recurrences among household members: an examination of host, behavioral, and pathogen-level predictors.

BACKGROUND: Many patients suffer from recurrent Staphylococcus aureus infections, but there are few data examining recurrence predictors. METHODS: We followed adults and children after treatment for S. aureus skin infections and their household contacts in Los Angeles and Chicago. We surveyed subjects for S. aureus body colonization, household fomite contamination, and behavioral and clinical factors at baseline and 3 and 6 months later. Using repeated measures modeling, we examined host, pathogen, behavioral, and clinical factors associated with recurrence. RESULTS: Among 330 index subjects, 182 (55%) were infected with an isolate of the USA300 methicillin-resistant S. aureus (MRSA) genetic background. Recurrences occurred in 39% by month 3 and 51% by month 6. Among 588 household contacts, 10% reported a skin infection by month 3 and 13% by month 6. Among index subjects, recurrence was associated with (P < .05) Los Angeles site, diabetes, recent hospitalization, recent skin infection, recent cephalexin use, and household S. aureus or MRSA fomite contamination; recurrence was inversely associated with recent contact sports participation. In the multivariate model, independent predictors of recurrence in index patients were recent hospitalization, household MRSA fomite contamination, and lack of recent contact sports participation. Among household contacts, independent predictors of subsequent skin infection were Chicago site, antibiotic use in the prior year, and skin infection in the prior 3 months. CONCLUSIONS: In our longitudinal study, patients with a S. aureus skin infection were more likely to suffer a recurrence if household fomites were MRSA contaminated. Interventions to prevent recurrence may be enhanced by decontamination of household fomites.

Persistent environmental contamination with USA300 methicillin-resistant Staphylococcus aureus and other pathogenic strain types in households with S. aureus skin infections.

OBJECTIVE: To understand the genotypic spectrum of environmental contamination of Staphylococcus aureus in households and its persistence. DESIGN: Prospective longitudinal cohort investigation. SETTING: Index participants identified at 2 academic medical centers. PARTICIPANTS: Adults and children with S. aureus skin infections and their household contacts in Los Angeles and Chicago. METHODS: Household fomites were surveyed for contamination at baseline and 3 months. All isolates underwent genetic typing. RESULTS: We enrolled 346 households, 88% of which completed the 3-month follow-up visit. S. aureus environmental contamination was 49% at baseline and 51% at 3 months. Among households with a USA300 methicillin-resistant S. aureus (MRSA) body infection isolate, environmental contamination with an indistinguishable MRSA strain was 58% at baseline and 63% at 3 months. Baseline factors associated with environmental contamination by the index subject's infection isolate were body colonization by any household member with the index subject's infection isolate at baseline (odds ratio [OR], 10.93 [95% confidence interval (CI), 5.75-20.79]), higher housing density (OR, 1.47 [95% CI, 1.10-1.96]), and more frequent household fomite cleaning (OR, 1.62 [95% CI, 1.16-2.27]). Household environmental contamination with the index subject's infection strain at 3 months was associated with USA300 MRSA and a synergistic interaction between baseline environmental contamination and body colonization by any household member with the index subject's infection strain. CONCLUSIONS: We found that infecting S. aureus isolates frequently persisted environmentally in households 3 months after skin infection. Presence of pathogenic S. aureus strain type in the environment in a household may represent a persistent reservoir that places household members at risk of future infection.

Modeling the transmission of community-associated methicillin-resistant Staphylococcus aureus: a dynamic agent-based simulation.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has been a deadly pathogen in healthcare settings since the 1960s, but MRSA epidemiology changed since 1990 with new genetically distinct strain types circulating among previously healthy people outside healthcare settings. Community-associated (CA) MRSA strains primarily cause skin and soft tissue infections, but may also cause life-threatening invasive infections. First seen in Australia and the U.S., it is a growing problem around the world. The U.S. has had the most widespread CA-MRSA epidemic, with strain type USA300 causing the great majority of infections. Individuals with either asymptomatic colonization or infection may transmit CA-MRSA to others, largely by skin-to-skin contact. Control measures have focused on hospital transmission. Limited public health education has focused on care for skin infections. METHODS: We developed a fine-grained agent-based model for Chicago to identify where to target interventions to reduce CA-MRSA transmission. An agent-based model allows us to represent heterogeneity in population behavior, locations and contact patterns that are highly relevant for CA-MRSA transmission and control. Drawing on nationally representative survey data, the model represents variation in sociodemographics, locations, behaviors, and physical contact patterns. Transmission probabilities are based on a comprehensive literature review. RESULTS: Over multiple 10-year runs with one-hour ticks, our model generates temporal and geographic trends in CA-MRSA incidence similar to Chicago from 2001 to 2010. On average, a majority of transmission events occurred in households, and colonized rather than infected agents were the source of the great majority (over 95%) of transmission events. The key findings are that infected people are not the primary source of spread. Rather, the far greater number of colonized individuals must be targeted to reduce transmission. CONCLUSIONS: Our findings suggest that current paradigms in MRSA control in the United States cannot be very effective in reducing the incidence of CA-MRSA infections. Furthermore, the control measures that have focused on hospitals are unlikely to have much population-wide impact on CA-MRSA rates. New strategies need to be developed, as the incidence of CA-MRSA is likely to continue to grow around the world.

Staphylococcus aureus bacteremia at 5 US academic medical centers, 2008-2011: significant geographic variation in community-onset infections.

BACKGROUND: The incidence of community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) bacteremia rose from the late 1990s through the 2000s. However, hospital-onset (HO) MRSA rates have recently declined in the United States and Europe. METHODS: Data were abstracted from infection prevention databases between 1 January 2008 and 31 December 2011 at 5 US academic medical centers to determine the number of single-patient blood cultures positive for MRSA and methicillin-susceptible S. aureus (MSSA) per calendar year, stratified into CO and HO infections. RESULTS: Across the 5 centers, 4171 episodes of bacteremia were identified. Center A (Los Angeles, California) experienced a significant decline in CO-MRSA bacteremia rates (from a peak in 2009 of 0.42 to 0.18 per 1000 patient-days in 2011 [P = .005]), whereas CO-MSSA rates remained stable. Centers B (San Francisco, California), D (Chicago, Illinois), and E (Raleigh-Durham, North Carolina) experienced a stable incidence of CO-MRSA and CO-MSSA bacteremia. In contrast, at center C (New York, New York), the incidence of CO-MRSA increased >3-fold (from 0.11 to 0.34 cases per 1000 patient-days [P < .001]). At most of the sites, HO-MRSA decreased and HO-MSSA rates were stable. USA300 accounted for 52% (104/202) of genotyped MRSA isolates overall, but this varied by center, ranging from 35% to 80%. CONCLUSIONS: CO-MRSA rates and the contribution of USA300 MRSA varied dramatically across diverse geographical areas in the United States. Enhanced infection control efforts are unlikely to account for such variation in CO infection rates. Bioecological and clinical explanations for geographical differences in CO-MRSA bacteremia rates merit further study.

Recurrent urinary tract infections among women: comparative effectiveness of 5 prevention and management strategies using a Markov chain Monte Carlo model.

BACKGROUND: Recurrent urinary tract infections (UTIs) are a common problem among women. However, comparative effectiveness strategies for managing recurrent UTIs are lacking. METHODS: We performed a systematic literature review of management of women experiencing ≥3 UTIs per year. We then developed a Markov chain Monte Carlo model of recurrent UTI for each management strategy with ≥2 adequate trials published. We simulated a cohort that experienced 3 UTIs/year and a secondary cohort that experienced 8 UTIs/year. Model outcomes were treatment efficacy, patient and payer cost, and health-related quality of life. RESULTS: Five strategies had ≥2 clinical trials published: (1) daily antibiotic (nitrofurantoin) prophylaxis; (2) daily estrogen prophylaxis; (3) daily cranberry prophylaxis; (4) acupuncture prophylaxis; and (5) symptomatic self-treatment. In the 3 UTIs/year model, nitrofurantoin prophylaxis was most effective, reducing the UTI rate to 0.4 UTIs/year, and the most expensive to the payer ($821/year). All other strategies resulted in payer cost savings but were less efficacious. Symptomatic self-treatment was the only strategy that resulted in patient cost savings, and was the most favorable strategy in term of cost per quality-adjusted life-year (QALY) gained. CONCLUSIONS: Daily antibiotic use is the most effective strategy for recurrent UTI prevention compared to daily cranberry pills, daily estrogen therapy, and acupuncture. Cost savings to payers and patients were seen for most regimens, and improvement in QALYs were seen with all. Our findings provide clinically meaningful data to guide the physician-patient partnership in determining a preferred method of prevention for this common clinical problem.

A systematic literature review and meta-analysis of factors associated with methicillin-resistant Staphylococcus aureus colonization at time of hospital or intensive care unit admission.

OBJECTIVE: Screening for methicillin-resistant Staphylococcus aureus (MRSA) in high-risk patients is a legislative mandate in 9 US states and has been adopted by many hospitals. Definitions of high risk differ among hospitals and state laws. A systematic evaluation of factors associated with colonization is lacking. We performed a systematic review of the literature to assess factors associated with MRSA colonization at hospital admission. DESIGN: We searched MEDLINE from 1966 to 2012 for articles comparing MRSA colonized and noncolonized patients on hospital or intensive care unit (ICU) admission. Data were extracted using a standardized instrument. Meta-analyses were performed to identify factors associated with MRSA colonization. RESULTS: We reviewed 4,381 abstracts; 29 articles met inclusion criteria (n = 76,913 patients). MRSA colonization at hospital admission was associated with recent prior hospitalization (odds ratio [OR], 2.4 [95% confidence interval (CI), 1.3-4.7]; P < .01), nursing home exposure (OR, 3.8 [95% CI, 2.3-6.3]; P < .01), and history of exposure to healthcare-associated pathogens (MRSA carriage: OR, 8.0 [95% CI, 4.2-15.1]; Clostridium difficile infection: OR, 3.4 [95% CI, 2.2-5.3]; vancomycin-resistant Enterococci carriage: OR, 3.1 [95% CI, 2.5-4.0]; P < .01 for all). Select comorbidities were associated with MRSA colonization (congestive heart failure, diabetes, pulmonary disease, immunosuppression, and renal failure; P < .01 for all), while others were not (human immunodeficiency virus, cirrhosis, and malignancy). ICU admission was not associated with an increased risk of MRSA colonization (OR, 1.1 [95% CI, 0.6-1.8]; P = .87). CONCLUSIONS: MRSA colonization on hospital admission was associated with healthcare contact, previous healthcare-associated pathogens, and select comorbid conditions. ICU admission was not associated with MRSA colonization, although this is commonly used in state mandates for MRSA screening. Infection prevention programs utilizing targeted MRSA screening may consider our results to define patients likely to have MRSA colonization.

Quantifying the impact of extranasal testing of body sites for methicillin-resistant Staphylococcus aureus colonization at the time of hospital or intensive care unit admission.

OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of healthcare-associated infections. Recent legislative mandates require nares screening for MRSA at hospital and intensive care unit (ICU) admission in many states. However, MRSA colonization at extranasal sites is increasingly recognized. We conducted a systematic review of the literature to identify the yield of extranasal testing for MRSA. DESIGN: We searched MEDLINE from January 1966 through January 2012 for articles comparing nasal and extranasal screening for MRSA colonization. Studies were categorized by population tested, specifically those admitted to ICUs and those admitted to hospitals with a high prevalence (6% or greater) or low prevalence (less than 6%) of MRSA carriers. Data were extracted using a standardized instrument. RESULTS: We reviewed 4,381 abstracts and 735 articles. Twenty-three articles met the criteria for analysis ((n = 39,479 patients). Extranasal MRSA screening increased the yield by approximately one-third over nares alone. The yield was similar at ICU admission (weighted average, 33%; range, 9%-69%) and hospital admission in high-prevalence (weighted average, 37%; range, 9%-86%) and low-prevalence (weighted average, 50%; range, 0%-150%) populations. For comparisons between individual extranasal sites, testing the oropharynx increased MRSA detection by 21% over nares alone; rectum, by 20%; wounds, by 17%; and axilla, by 7%. CONCLUSIONS: Extranasal MRSA screening at hospital or ICU admission in adults will increase MRSA detection by one-third compared with nares screening alone. Findings were consistent among subpopulations examined. Extranasal testing may be a valuable strategy for outbreak control or in settings of persistent disease, particularly when combined with decolonization or enhanced infection prevention protocols.