Description of an Enterococcus faecium genotype vanB outbreak in a hospitalization ward

Vancomycin-resistant Enterococcus faecium (VRE) infections have increased in the last years. Hospital outbreaks have been described with a challenging microbiological diagnosis and control of the transmission.

This is a prospective study of a nosocomial outbreak of VRE in a conventional hospitalization ward. Three clinical samples of VRE genotype vanB (vanB VRE) were detected in two surgical wards. Epidemiological control measures were implemented, including contact isolation, patients from clean surgery ward transferred to other wards, staff training, weekly screening with rectal swab and environmental study.

In a 3-month follow-up period, rectal screening was performed on a total of 314 patients, being positive for vanB VRE 51 patients (16.2%). A study of the surface of the common areas with exclusive use by healthcare personnel detected vanB VRE in 28% of the samples. All the strains of VRE analyzed by MLST were ST117, which belongs to clonal complex 17. Hand hygiene observations show proper adherence in 56% of the events monitored. Notwithstanding the large number of colonized patients, just one patient had a relevant infection requiring treatment, with good evolution.

The survival of VRE on surfaces and the poor adherence to hand hygiene might have contributed to repetitively infect surfaces, perpetuating the outbreak. After 10 months without positive clinical samples, it was decided to suspend the screening, even though there were still screening positive results. Despite its spread, the clinical impact was low, possibly because the outbreak took place in a ward without severe immunosuppressed patients. The frequent isolation of VRE on surfaces which were exclusive from healthcare personnel areas, indicates how important is the disinfection of these areas.