Outbreaks of Vancomycin-Resistant Enterococci in Hospital Settings: A Systematic Review and Calculation of the Basic Reproductive Number

Abstract

BACKGROUNDVancomycin-resistant enterococci (VRE) have spread worldwide.OBJECTIVETo systematically review VRE outbreaks and estimate the pooled basic reproductive rate (R0) of VRE.METHODSEligible studies criteria were (1) published within 10 years, (2) report outbreak details, (3) involve 1 center, (4) estimate epidemic duration, and (5) concern adults. Descriptive analysis included number of index cases, secondary cases, and screened patients; infection control measures; and definition of contact patients. R0 was estimated by the equation R0=(ln2) D/td+1, with D as the generation time and td as the doubling time.RESULTSThirteen VRE outbreaks were retained from 180 articles and, among them, 10 were kept for R0 calculation. The mean (range) number of index cases was 2.3 (1–8) and the mean (range) number of secondary cases was 15 (3–56). The mean (range) number of screened patients was 174 (32–509), with pooled VRE prevalence of 5.4% (95% CI, 4.5%–6.3%). Contact precautions were reported in 12 studies (92%), wards were closed in 7 (54%), with cohorting in 6 (46%). Two major screening policies were implemented: (1) a surveillance program in the unit or hospital (7 studies [54%]) and (2) screening of selected contact patients (6 studies [46%]). The pooled R0 of VRE was 1.32 (interquartile range, 1.03–1.46).CONCLUSIONWe discerned considerable heterogeneity in screening policies during VRE outbreaks. Pooled R0 was higher than 1, confirming the epidemic nature of VRE.Infect. Control Hosp. Epidemiol. 2016;37(3):289–394