An active surveillance study of vancomycin-resistant Enterococcus in Queen Elizabeth Hospital, Hong Kong

VWM Chuang, DNC Tsang, JKS Lam, RKW Lam, WH Ng
Department of Pathology, Queen Elizabeth Hospital, 30 Gascoigne Road, Hong Kong

OBJECTIVE. To assess the rate of faecal vancomycin-resistant Enterococcus colonisation in high-risk patients in a regional hospital.

DESIGN. Prospective observational surveillance study.

SETTING. Queen Elizabeth Hospital, Hong Kong.

PATIENTS. From September 2001 to December 2002, stool samples from patients in the intensive care unit and patients in whom Clostridium difficile testing was requested were used for study using a broth enrichment method.

MAIN OUTCOME MEASURES. Number of faecal vancomycin-resistant Enterococcus colonisation.

RESULTS. A total of 2414 cultures from 1792 patients were tested for vancomycin-resistant Enterococcus using a broth enrichment method. Only one (0.06%) patient was found to harbour a vancomycin-resistant Enterococcus faecalis in the gastro-intestinal tract. Surveillance cultures from contacts of the case revealed another six with vancomycin-resistant Enterococcus faecalis. Vancomycin-resistant Enterococcus faecalis was also later reported from a clinical specimen (catheterized urine) of another patient. They were all epidemiologically linked to the index case. Mean inhibitory concentrations of vancomycin and teicoplanin were determined to be higher than 256 and 0.5 ug/mL, respectively by E-test for all the vancomycin-resistant Enterococcus isolates. Polymerase chain reaction analysis confirmed the presence of vanB genes and the result was in line with the phenotype. Pulsed-field gel electrophoresis confirmed a monoclonal vancomycin-resistant Enterococcus outbreak. Strict infection control measures recommended by the Centers for Disease Control and Prevention were followed and the outbreak was successfully controlled.

CONCLUSION. Vancomycin-resistant Enterococcus colonisation is rare, but present among high-risk patients in our hospital. A routine surveillance programme should be implemented that will enable early case detection and prompt initiation of infection control measures to prevent the emergence of an endemic situation.

Hong Kong Med J 2005;11:463-71

Key words: Clostridium infections; Cross infection; Enterococcus; Feces/microbiology; Vancomycin resistance