1. The Cefazolin Inoculum Effect and the Presence of type A blaZ Gene according to agr Genotype in Methicillin-Susceptible Staphylococcus aureus Bacteremia
- Author
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Soon Ok Lee, Jeong Eun Lee, Shinwon Lee, Sun Hee Lee, and Sohee Park
- Subjects
Staphylococcus aureus ,medicine.drug_class ,Antibiotics ,Cefazolin ,Erythromycin ,medicine.disease_cause ,Microbiology ,03 medical and health sciences ,0302 clinical medicine ,Genotype ,Multiplex polymerase chain reaction ,medicine ,Pharmacology (medical) ,030212 general & internal medicine ,0303 health sciences ,030306 microbiology ,business.industry ,Inoculum effect ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,bacterial infections and mycoses ,Quorum sensing ,Infectious Diseases ,Bacteremia ,bacteria ,Original Article ,business ,Methicillin Susceptible Staphylococcus Aureus ,medicine.drug - Abstract
BACKGROUND Recent data suggests the inoculum effect of methicillin-susceptible Staphylococcus aureus (MSSA) against beta-lactam antibiotics and their association with functionality or genotypic variation of agr locus. METHODS MSSA blood isolates were collected at a tertiary care hospital in Korea from June 2014 to December 2017. The functionality of the agr operon was measured by δ-hemolysin assays. Multiplex PCR was performed to determine the agr genotype. The cefazolin minimum inhibitory concentrations (MICs) at a high inoculum concentration (~5 × 10⁷ CFU/ml) were compared to the MICs at a standard inoculum concentration (~5 × 10⁵ CFU/ml) to identify strains with the cefazolin inoculum effect (CIE). The DNA sequencing of blaZ gene was performed to classify the blaZ genotype. RESULTS Among the 195 MSSA blood isolates, agr genotype I was most common (68.2%), followed by type III (16.4%), type IV (9.2%), and type II (6.2%). Sixty-seven (34.3%) MSSA isolates had dysfunctional agr, but neither CIE nor blaZ genotype was associated with dysfunctional agr. The MSSA with agr type III genotype exhibited significantly higher CIE positivity (agr III 43.8% vs. non-agr III 5.5%, P
- Published
- 2019