Trafficking of methicillin-resistant staphylococci and co-colonization with vancomycin-resistant enterococci

ABSTRACT

To determine the trafficking of methicillin-resistant staphylococci between the hospital and community as well as the occurrence of co-colonization with vancomycin-resistant enterococci [VRE]. From November 2005 to April 2006, methicillin-resistant Staphylococcus aureus [MRSA] and methicillin-resistant coagulase-negative Staphylococcus [MRCoNS]-positive patients at the Salmaniya Medical Complex, Bahrain were assessed for VRE co-colonization. Characterization of vancomycin resistance genotype by PCR was carried out. Close family contacts were screened for MRSA and pulsed-field gel electrophoresis [PFGE] analysis of MRSA isolates from patient-family member pairs was conducted. One hundred and eighty-two patients [93 MRSA; 89 MRCoNS] and 356 family members were enrolled. Seven MRSA and 41 MRCoNS strains were isolated from the family members. PFGE analysis revealed the presence of variants of a single MRSA clone among patients and their relatives. A total of 112 patients [62 MRSA; 50 MRCoNS] provided stool for VRE screening. Of these 13 stool specimens [11.6%] were VRE-positive. All the VRE isolates were from MRSA-positive patients, thus positivity rate among MRSA patients was 20.9% [n/N = 13/62]. These were predominantly Enterococcus gallinarum with vanC1 genotype and one strain was Enterococcus faecium [vanB genotype]. Two E. gallinarum isolates harbored an additional vanB gene. The majority of VRE isolates were from patients in medical and surgical units [n/N = 10/13; 77%]. Male gender, prolonged hospitalization and presence of co-morbidities were significantly associated with MRSA/VRE co-colonization [p < 0.05]. MRSA/VRE co-colonization with MRSA trafficking between the hospital and community environment is a public health concern occurring in our setting: