Back to basics: hand hygiene and isolation

Lin Huang, G. Khai; Stewardson, Andrew J.; Lindsay Grayson, M.

Eyre et al. [88 && ] performed whole genome sequencing of all C. difficile isolates from symptomatic patients over a 3-year period in Oxfordshire, in the United Kingdom. They found that 45% of the cases were due to transmission from either environmental reservoirs, or transmission from asymptomatic carriers, rather than previous symptomatic hospital cases. Asymptomatic carriage (and presumably shedding) is known to be relatively common [89, 90] . These findings support a greater emphasis on improved antimicrobial stewardship to minimize emergence of clinical disease, in addition to prevention of cross-transmission [88 && ]. The epidemiology of VRE transmission may not be dissimilar. Using large-scale comparative genomics, Howden et al. [91 & ] demonstrated that the epidemiology of hospital vanB VRE was more complex than previously thought. They and others [92, 93] have proposed a model in which silent circulation of closely related vancomycin-susceptible Enterococcus faecium isolates acquires the vanB operon via lateral gene transfer from anaerobic bacteria in the gastrointestinal tract. Hence, hospitalacquired vanB VRE may also be driven by de-novo generation rather than solely nosocomial transmission via direct contact. This is in keeping with previous work by Johnson et al. [94] , in which it was observed within an institution that each time a new vancomycin-resistant E. faecium (VREfm) sequence type appeared, it was observed first as vancomycinsensitive E. faecium (VSEfm). This may explain why the incidence of VRE has continued to rise in many countries despite strict patient isolation, effective infection control measures and significant reduction rates of nonenteric pathogens, such as MRSA [94, 95] .