Antibiotic treatment for asymptomatic bacteriuria (ASB) is prevalent but often contrary to published guidelines.

To evaluate risk factors for treatment of ASB.

Retrospective observational study.

A tertiary academic hospital, county hospital, and community hospital.

Hospitalized adults with bacteriuria.

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.

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%.

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.

Infect. Control Hosp. Epidemiol. 2016;37(3):319–326

To understand the genotypic spectrum of environmental contamination of Staphylococcus aureus in households and its persistence

Prospective longitudinal cohort investigation.

Index participants identified at 2 academic medical centers.

Adults and children with S. aureus skin infections and their household contacts in Los Angeles and Chicago.

Household fomites were surveyed for contamination at baseline and 3 months. All isolates underwent genetic typing.

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.

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.

Infect Control Hosp Epidemiol 2014;35(11):1373–1382

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.

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.

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).

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.

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.

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.

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%.

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.