INTRODUCTIONCommunity-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged worldwide. In contrast to healthcare-associated MRSA (HA-MRSA), CA-MRSA isolates are usually susceptible to multiple non-beta-lactam antibiotics and cause a distinct spectrum of infections in epidemiologically disparate populations - in particular, cutaneous abscesses, necrotising fasciitis and necrotising pneumonia. They arise from a broader genetic background, and possess differing virulence genes. We aim to describe the distribution of different molecular subtypes of CA-MRSA among various regions and discuss briefly the implications of CA-MRSA from a local perspective.

METHODSLiterature review of articles on CA-MRSA, focusing mainly on reports where the genetic background of isolates had been analysed using multi-locus sequence typing (MLST). Singapore data were obtained from the local CA-MRSA database.

RESULTSMLST analysis demonstrated the presence of epidemic subtypes of CA-MRSA within most geographic areas. In parts of the United States, community MRSA infections currently exceed those caused by their methicillin-susceptible counterparts. In Singapore, CA-MRSA infections are increasing, predominantly as a result of the spread of ST30 clones.

CONCLUSIONAvailable evidence suggests that the emergence of MRSA from the community is not going to be a transient phenomenon. Local guidelines for dealing with this phenomenon at both therapeutic and preventive levels are needed prior to the potential development of a situation mirroring that of meso-endemic HA-MRSA in local hospitals or CA-MRSA epidemics in parts of USA.

Bacterial Typing Techniques ; Community-Acquired Infections ; epidemiology ; microbiology ; Cross Infection ; diagnosis ; microbiology ; Humans ; Methicillin Resistance ; Risk Factors ; Singapore ; epidemiology ; Staphylococcal Infections ; epidemiology ; microbiology ; Staphylococcus aureus ; classification ; drug effects

BACKGROUND: The BD GeneOhm MRSA PCR assay (Becton Dickinson, USA) is a qualitative real-time PCR test for rapid detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the performance of BD GeneOhm MRSA PCR assay versus MRSASelect (Bio-Rad, France) and broth enrichment cultures for detection of MRSA from nasal swabs. METHODS: From August 2008 to January 2009, 295 nasal swabs were taken from patients in intensive care units and transported to the laboratory with BD CultureSwab Liquid Stuart Single Swab (Becton Dickinson, USA). The swabs were inoculated onto MRSASelect first and then suspended into GeneOhm sample buffer: 100 microliter of the suspension was inoculated into 6.5% NaCl-tryptic soy broth (Becton Dickinson, USA), which was subcultured on MRSASelect after overnight incubation (TSBS). Performances of GeneOhm MRSA and MRSASelect were compared to TSBS. RESULTS: With GeneOhm MRSA, 125 swabs (44.6%) were positive for MRSA, 13 (4.4%) were unresolved, and 2 were not determined. With MRSASelect and TSBS 86 (29.4%) and 106 swabs (36.2%), respectively, were positive. The sensitivity, specificity, and positive and negative predictive value of GeneOhm MRSA were 85.8%, 77.5%, and 72.8% and 93.5%, respectively, and corresponding values for MRSASelect were 78.3%, 94.8%, and 96.5% and 88.9%. Of the 33 patients whose 34 specimens were found false positive in GeneOhm MRSA, 23 patients were MRSA-positive either previously or subsequently to this study. All of the 10 patients with false-negative specimens in GeneOhm MRSA PCR assay were previously MRSA or methicilln-resistant coagulase negative staphylococci (MRCNS)-positive and were treated for MRSA, but they became MRSA-positive after 1 to 4 negative surveillance cultures. CONCLUSIONS: GeneOhm MRSA PCR assay showed a relatively high negative predictive value. However, its low specificity and frequent occurrence of unresolved results would be problematic in the endemic areas with a high prevalence of MRSA.
Endemic Diseases ; Humans ; Intensive Care Units ; Methicillin-Resistant Staphylococcus aureus/genetics/*isolation & purification ; Nose/*microbiology ; Polymerase Chain Reaction/*methods ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; Staphylococcal Infections/*diagnosis/epidemiology

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) are important pathogens causing nosocomial infections in Korean hospitals. This study aimed to investigate the epidemiological and genetic diversity of clinical S. aureus isolates in healthcare settings from 2001 to 2008. METHODS: Samples and data were obtained from 986 individuals as part of the National Antimicrobial Surveillance Project, involving 10 regions nationwide. Molecular typing studies, including multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing were performed, and a representative clone of Korean MRSA was classified by combinational grouping using a DiversiLab (DL; bioMérieux, France) repetitive element polymerase chain reaction (rep-PCR) system. RESULTS: Nine Korean MRSA clones (KMRSA-1 to -9) were identified by analysis of genetic backgrounds and molecular characteristics. KMRSA-1 to -3, expressing clonal complex (CC) 5 (carrying SCCmec II), CC8 (carrying SCCmec III), and CC72 (carrying SCCmec IV) were spread nationwide. In contrast, KMRSA-6 was highly prevalent in Gyeongsangnam-do, and KMRSA-4 was highly prevalent in Jeollanam-do and Jeollabuk-do. CONCLUSIONS: Epidemic KMRSA clones were genetically similar to major clones identified from the USA, with the exception of KMRSA-2, which had the SCCmec III type. Our results provide important insights into the distribution and molecular genetics of MRSA strains in Korea and may aid in the monitoring of MRSA spread throughout the country.
Bacterial Proteins/genetics ; DNA, Bacterial/genetics/metabolism ; Electrophoresis, Gel, Pulsed-Field ; Hospitals ; Humans ; Methicillin-Resistant Staphylococcus aureus/*genetics/isolation & purification ; Multilocus Sequence Typing ; Multiplex Polymerase Chain Reaction ; Prevalence ; Republic of Korea/epidemiology ; Staphylococcal Infections/diagnosis/*epidemiology/microbiology

The incidence and mortality of infective endocarditis (IE) in patients with severe burn remain high, which are attributed to invasive procedures, bacteremia, and wound infection after burns. Clinical clues for IE in burns are usually masked by burn-related manifestations, so the diagnosis of IE may be delayed or missed. For burned patients with persistent bacteremia of unknown source, especially Staphylococcus aureus-induced bacteremia, the diagnosis of IE should be considered according to the Duke criteria, and early echocardiography performance is particularly important. Antibiotic therapy is the mainstay initial management, and early surgical intervention is strongly recommended once IE is clearly diagnosed in patients with burns. In order to lower the incidence and mortality of IE in burns, it is very important to take prophylactic procedures along with the whole course of burn management.
Bacteremia ; epidemiology ; Burn Units ; Burns ; complications ; mortality ; surgery ; Endocarditis, Bacterial ; complications ; diagnosis ; microbiology ; mortality ; Humans ; Incidence ; Severity of Illness Index ; Staphylococcal Infections ; complications ; diagnosis ; Staphylococcus aureus ; isolation & purification ; Surgery, Plastic ; Wound Infection ; etiology ; mortality

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