Evaluation of Latex Agglutination Test Kit for Rapid Detection of Methicillin-Resistance in Staphylococcus aureus / 대한임상병리학회지

BACKGROUND: The identification of methicillin-resistant Staphylococcus aureus (MRSA) in the clinical laboratory has been typically performed by using methods that detect phenotypic expression of resistance determinants. However, these methods are not always reliable since phenotypic expression of methicillin resistance is known to be heterogeneous. In this study, MRSA-Screen test (Denka Seiken Co., Ltd., Tokyo, Japan), consisting of a slide latex agglutination kit that detects PBP 2a with a monoclonal antibody, was compared to the oxacillin disk diffusion test, the oxacillin-salt agar screen, agar dilution MIC and PCR of the mecA gene for the detection of methicillin resistance in S. aureus. METHODS: A total of 48 MRSA and 46 methicillin-susceptible S. aureus (MSSA) clinical isolates, defined by the presence or absence of the mecA gene, respectively, were tested. RESULTS: The MRSA-Screen test, the oxacillin disk diffusion test, and the oxacillin-salt agar screening test showed sensitivity of 97.9%, 93.8%, and 97.9% and specificity of 100% in all three tests. CONCLUSION: We conclude that the MRSA-Screen test is very accurate, reliable and easy to perform for detection of methicillin resistance in S. aureus.

Two Cases of Bacteremia Caused by Leuconostoc citreum / 대한임상병리학회지

Two strains of vancomycin-resistant Leuconostoc species were isolated from blood cultures in two compromised patients. The isolates produced gas from Lactobacillus MRS booth, hydrolysed esculin, and produced no ammonia from arginine, thus fulfilling the major criteria as Leucorostoc spp. We recommend that clinical laboratories should perform susceptibility test to vancomycin for clinical isolates (especially from cerebrospinal fluid and blood) which resemble streptococci so as not to confuse Leuconostoc spp. with more commonly isolated pathogens such as streptococci.