Community- and Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Strains: An Investigation Into Household Transmission, Risk Factors, and Environmental Contamination.

OBJECTIVE To measure transmission frequencies and risk factors for household acquisition of community-associated and healthcare-associated (HA-) methicillin-resistant Staphylococcus aureus (MRSA). DESIGN Prospective cohort study from October 4, 2008, through December 3, 2012. SETTING Seven acute care hospitals in or near Toronto, Canada. PARTICIPANTS Total of 99 MRSA-colonized or MRSA-infected case patients and 183 household contacts. METHODS Baseline interviews were conducted, and surveillance cultures were collected monthly for 3 months from household members, pets, and 8 prespecified high-use environmental locations. Isolates underwent pulsed-field gel electrophoresis and staphylococcal cassette chromosome mec typing. RESULTS Overall, of 183 household contacts 89 (49%) were MRSA colonized, with 56 (31%) detected at baseline. MRSA transmission from index case to contacts negative at baseline occurred in 27 (40%) of 68 followed-up households. Strains were identical within households. The transmission risk for HA-MRSA was 39% compared with 40% (P=.95) for community-associated MRSA. HA-MRSA index cases were more likely to be older and not practice infection control measures (P=.002-.03). Household acquisition risk factors included requiring assistance and sharing bath towels (P=.001-.03). Environmental contamination was identified in 78 (79%) of 99 households and was more common in HA-MRSA households. CONCLUSION Household transmission of community-associated and HA-MRSA strains was common and the difference in transmission risk was not statistically significant. Infect Control Hosp Epidemiol 2016;1-7.

Methicillin-resistant Staphylococcus aureus colonization among health care workers in a downtown emergency department in Toronto, Ontario.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) acquired in the community, otherwise known as community-acquired MRSA, has emerged rapidly in recent years. Colonization with MRSA has been associated with an increased risk of symptomatic and serious infections and, in some settings, health care workers (HCWs) exhibit a higher prevalence of MRSA colonization. OBJECTIVE: To determine MRSA colonization in emergency department (ED) HCWs in the setting of a moderate prevalence of MRSA in skin and soft tissue infections. METHODS: The present study was conducted at a downtown ED in Toronto, Ontario. ED HCWs completed a brief questionnaire and swabs were taken from one anterior nare, one axilla and any open wounds (if present). Swabs were processed using standard laboratory techniques. RESULTS: None of the 89 staff (registered nurses [n=55], physicians [n=15], other [n=19]) were MRSA positive and 25 (28.1%) were colonized with methicillin-susceptible S aureus. CONCLUSIONS: Contrary to common belief among HCWs and previous studies documenting MRSA colonization of HCWs, MRSA colonization of this particular Canadian ED HCW cohort was very low and similar to that of the local population.

HISTORIQUE: Le Staphylococcus aureus résistant à la méthicilline (SARM) d'origine non nosocomiale, ou SARM d'origine communautaire, a émergé rapidement ces dernières années. La colonisation par le SARM s'associe à une augmentation du risque d'infections graves et symptomatiques. Dans certains milieux, les travailleurs de la santé (TdS) présentent une prévalence plus élevée de colonisation par le SARM. OBJECTIF: Déterminer la colonisation par le SARM desTdS d'un département d'urgence (DU) où l'on observe une prévalence modérée de SARM en cas d'infections de la peau et des tissus mous. MÉTHODOLOGIE: Les chercheurs ont mené la présente étude dans un DU du centre-ville de Toronto, en Ontario. Les TdS du DU ont rempli un bref questionnaire et effectué un prélèvement dans une narine, sous l'aisselle et dans leurs plaies ouvertes (le cas échéant). Les prélèvements ont été traités au moyen de techniques de laboratoire standard. RÉSULTATS: Aucun des 89 employés (infirmières diplômées [n=55], médecins [n=15], autres [n=19]) n'était positif au SARM, mais 25 (28,1 %) étaient colonisés par le S aureus susceptible à la méthicilline. CONCLUSIONS: Contrairement aux idées reçues chez les TdS et aux études antérieures étayant la colonisation des TdS par le SARM, la colonisation par le SARM de cette cohorte de TdS d'un DU canadien était très faible et similaire à celle de la population locale.

Prevalence and incidence of antimicrobial-resistant organisms among hospitalized inflammatory bowel disease patients.

BACKGROUND: Patients with inflammatory bowel disease (IBD) experience frequent hospitalizations and use of immunosuppressive medications, which may predispose them to colonization with antimicrobial-resistant organisms (ARO). OBJECTIVE: To determine the prevalence of ARO colonization on admission to hospital and the incidence of infection during hospitalization among hospitalized IBD patients. METHODS: A chart review comparing the prevalence of colonization and incidence of infection with methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL) in hospitalized IBD patients with those of non-IBD controls was performed. RESULTS: On admission, there were no significant differences between IBD inpatients and controls in the prevalence of colonization of methicillin-resistant S aureus (1.0% versus 1.2%; P=0.74), vancomycin-resistant enterococci (0.2% versus 0%; P=1.0) or ESBL (4.1% versus 5.5%; P=0.33). Pooling data from historical clinic-based cohorts, IBD patients were more likely than controls to have ESBL colonization (19% versus 6.6%; P<0.05). Antibiotic use on admission was associated with ESBL colonization among IBD inpatients (OR 4.2 [95% CI 1.4 to 12.6]). The incidence of ARO infections during hospitalization was not significantly different between IBD patients and controls. Among IBD patients who acquired ARO infections during hospitalizations, the mean time interval from admission to infection was shorter for those who were already colonized with ARO on admission. CONCLUSIONS: This particular population of hospitalized IBD patients was not shown to have a higher prevalence or incidence of ARO colonization or infection compared with non-IBD inpatients.

HISTORIQUE: Les patients atteints d'une maladie inflammatoire de l'intestin (MII) sont souvent hospitalisés et prennent souvent des immunosuppresseurs, ce qui peut les prédisposer à des organismes résistants aux antimicrobiens (ORA). OBJECTIF: Déterminer la prévalence de colonisation par des ORA à l'admission à l'hôpital ainsi que l'incidence d'infection pendant l'hospitalisation de patients atteints d'une MII. MÉTHODOLOGIE: Les chercheurs ont procédé à l'analyse des dossiers comparant la prévalence de colonisation et d'incidence d'infection par le Staphylococcus aureus résistant à la méthicilline (SARM), les entérocoques résistant à la vancomycine (EVM) et les entérobactériacées productrices de bêta-lactamase à spectre étendu (BLSE) des patients hospitalisés atteints d'une MII à celle de sujets témoins n'ayant pas de MII. RÉSULTATS: À l'admission, les chercheurs n'ont pas constaté de dif-férences significatives entre les patients hospitalisés atteints d'une MII et les sujets témoins pour ce qui est de la prévalence de colonisation par le SARM (1,0 % par rapport à 1,2 %; P=0,74), les EVM (0,2 % par rapport à 0 %; P=1,0) ou les BLSE (4,1 % par rapport à 5,5 %; P=0,33). Selon les données regroupées de cohortes cliniques rétrospectives, les patients atteints d'une MII étaient plus susceptibles que les sujets témoins d'être colonisés par des BLSE (19 % par rapport à 6,6 %; P<0,05). L'utilisation d'antibiotiques à l'admission s'associait à une colonisation par les BLSE chez les patients atteints d'une MII (RRR 4,2 [95 % IC1,4 à 12,6]). L'incidence d'infections par des ORA pendant l'hospitalisation n'était pas significativement différente entre les patients atteints d'une MII et les sujets témoins. Chez les patients atteints d'une MII qui avaient contracté une infection par des ORA pendant l'hospitalisation, l'intervalle moyen entre l'admission et l'infection était plus court pour ceux qui étaient déjà colonisés par des ORA à l'admission. CONCLUSIONS: Cette population de patients hospitalisés atteints d'une MII ne présentait pas de prévalence ou d'incidence plus élevée de colonisation par des ORA que les patients n'ayant pas de MII.

Prevalence and predictors of MRSA, ESBL, and VRE colonization in the ambulatory IBD population.

BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) patients may be at increased risk of acquiring antibiotic-resistant organisms (ARO). We sought to determine the prevalence of colonization of methicillin-resistant Staphylococcus aureus (MRSA), Enterobacteriaceae containing extended spectrum beta-lactamases (ESBL), and vancomycin-resistant enterococi (VRE) among ambulatory IBD patients. METHODS: We recruited consecutive IBD patients from clinics (n=306) and 3 groups of non-IBD controls from our colon cancer screening program (n=67), the family medicine clinic (n=190); and the emergency department (n=428) from the same medical center in Toronto. We obtained nasal and rectal swabs for MRSA, ESBL, and VRE and ascertained risk factors for colonization. RESULTS: Compared to non-IBD controls, IBD patients had similar prevalence of colonization with MRSA (1.5% vs. 1.6%), VRE (0% vs. 0%), and ESBL (9.0 vs. 11.1%). Antibiotic use in the prior 3 months was a risk factor for MRSA (OR, 3.07; 95% CI: 1.10-8.54), particularly metronidazole. Moreover, gastric acid suppression was associated with increased risk of MRSA colonization (adjusted OR, 7.12; 95% CI: 1.07-47.4). Predictive risk factors for ESBL included hospitalization in the past 12 months (OR, 2.04, 95% CI: 1.05-3.95); treatment with antibiotics it the past 3 months (OR, 2.66; 95% CI: 1.37-5.18), particularly prior treatment with vancomycin or cephalosporins. CONCLUSIONS: Ambulatory IBD patients have similar prevalence of MRSA, ESBL and VRE compared to non-IBD controls. This finding suggests that the increased MRSA and VRE prevalence observed in hospitalized IBD patients is acquired in-hospital rather than in the outpatient setting.