In July 2010, we identified an outbreak of vancomycin-resistant enterococci (VRE) in our 26-bed neonatal intensive care unit. We performed an epidemiological investigation after clinical cultures of 2 neonates were positive for VRE. Identification, susceptibility testing, and molecular characterization were performed. Cultures of 3 surveillance stool samples of inpatients and 5 environmental samples were positive for VRE. All isolates were identified as Enterococcus faecium containing the vanA gene. Two distinct clones were identified by performing pulsed-field gel electrophoresis. The 2 clones exhibited different pulsotypes, but they represented identical Tn1546 types. Two sequence types, ST18 and ST192, were identified among all of the isolates with multilocus sequence typing. Our investigation determined that the outbreak in the neonatal intensive care unit was caused by 2 genetically different clones. The outbreak may have occurred through clonal spread and horizontal transfer of the van gene.
Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/genetics ; Bacterial Typing Techniques ; Carbon-Oxygen Ligases/genetics ; DNA, Bacterial/analysis ; *Disease Outbreaks ; Electrophoresis, Gel, Pulsed-Field ; Enterococcus faecium/drug effects/*genetics/isolation & purification ; Feces/microbiology ; Genotype ; Gram-Positive Bacterial Infections/diagnosis/epidemiology/*microbiology ; Humans ; Infant, Newborn ; Intensive Care Units, Neonatal ; Male ; Multilocus Sequence Typing ; Vancomycin/pharmacology ; *Vancomycin Resistance

BACKGROUND/AIMS: Liver transplant patients are at high risk for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) colonization. We evaluated patients before and after liver transplant using active surveillance culture (ASC) to assess the prevalence of MRSA and VRE and to determine the effect of bacterial colonization on patient outcome. METHODS: We performed ASC on 162 liver transplant recipients at the time of transplantation and 7 days posttransplantation to monitor the prevalence of MRSA and VRE. RESULTS: A total of 142 patients had both nasal and rectal ASCs. Of these patients, MRSA was isolated from 12 (7.4%) at the time of transplantation (group 1a), 9 (6.9%) acquired MRSA posttransplantation (group 2a), and 121 did not test positive for MRSA at either time (group 3a). Among the three groups, group 1a patients had the highest frequency of developing a MRSA infection (p < 0.01); however, group 2a patients had the highest mortality rate associated with MRSA infection (p = 0.05). Of the 142 patients, VRE colonization was detected in 37 patients (22.8%) at the time of transplantation (group 1b), 21 patients (20%) acquired VRE posttransplantation (group 2b), and 84 patients did not test positive for VRE at either time (group 3b). Among these three groups, group 2b patients had the highest frequency of VRE infections (p < 0.01) and mortality (p = 0.04). CONCLUSIONS: Patients that acquired VRE or MRSA posttransplantation had higher mortality rates than did those who were colonized pre-transplantation or those who never acquired the pathogens. Our findings highlight the importance of preventing the acquisition of MRSA and VRE posttransplantation to reduce infections and mortality among liver transplant recipients.
Adult ; Enterococcus/*isolation & purification ; Female ; Gram-Positive Bacterial Infections/diagnosis/*microbiology/mortality/transmission ; Humans ; Liver Transplantation/*adverse effects/mortality ; Male ; Methicillin-Resistant Staphylococcus aureus/*isolation & purification ; Middle Aged ; Prevalence ; Prospective Studies ; Republic of Korea/epidemiology ; Risk Factors ; Staphylococcal Infections/diagnosis/*microbiology/mortality/transmission ; Time Factors ; Treatment Outcome ; *Vancomycin Resistance