Aims: To investigate clonality among clinical Enterococcus faecium isolates and normal intestinal microflora isolates as well as cross-transmission between patients in relation to the presence of the esp gene and antibiotic resistance.
Methods and results: Blood-culture isolates (n = 101) deriving from tertiary, secondary and primary hospitals were analysed. Antibiotic susceptibility was investigated. Polymerase chain reaction and pulsed-field gel electrophoresis were used for detection of esp and genotyping, respectively. Nearly half (43%) of the patients included were involved in a cross-transmission event with Ent. faecium. These strains disseminated both within and between all hospitals. The antibiotic resistance and presence of esp were highest in isolates from the tertiary hospital. Isolates harbouring esp showed less genetic diversity compared with esp negative ones.
Conclusions: Cross-transmission with Ent. faecium between patients was readily detected, indicating that hospital-adapted clones circulate within and between hospitals. Acquired characteristics, such as antibiotic resistance and esp, seem to accumulate in the isolates disseminating in the tertiary hospital.
Significance and impact of the study: It is important to characterize Ent. faecium isolates causing infections and to determine the extent of dissemination in order to prevent further spread of these pathogens.