title: More accurate measurement of vancomycin minimum inhibitory concentration indicates poor outcomes in meticillin-resistant Staphylococcus aureus bacteraemia.
abstract: Meticillin-resistant Staphylococcus aureus (MRSA) is an important pathogen associated with community-acquired and nosocomial infections. The aim of this study was to validate the vancomycin (VAN) minimum inhibitory concentration (MIC) and administration of VAN that may affect the prognosis of patients with MRSA bacteraemia. In total, 140 clinical MRSA strains from blood cultures were collected from January 2009 to December 2013 at a university hospital in Tokyo (Japan). Patient background, their clinical situation and the susceptibility of isolates to anti-MRSA agents in all cases were reviewed, and factors contributing to 30-day mortality were analysed. Susceptibility to anti-MRSA agents was measured by a microdilution susceptibility testing method. The VAN MIC was further evaluated at 0.25 μg/mL intervals from 0.5 μg/mL to 2.0 μg/mL. Multiple logistic regression analysis revealed a 4-fold increase in mortality of patients with a VAN MIC ≥1.5 μg/mL [odds ratio (OR)=3.952, 95% confidence interval (CI) 1.471-10.614; P=0.006]. A one-score increase in the Charlson co-morbidity index resulted in a 1.2-fold increase in the risk of death (OR=1.199, 95% CI 1.054-1.364; P=0.006). However, no significant difference was found in the ratio of the VAN 24-h area under the concentration-time curve to MIC between VAN MIC ≥1.5 μg/mL and <1.5 μg/mL. A significant increase in the MICs of teicoplanin and daptomycin was observed in strains with high VAN MICs. For patients with high VAN MICs, administration of these anti-MRSA antibiotics may have a poor outcome owing to cross-resistance.
authors.affiliation: Division of Clinical Infectious Diseases, Department of Medicine, School of Medicine, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo 142-0064, Japan. Electronic address: itrshoji@med.showa-u.ac.jp.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Shoji
authors.affiliation: Division of Infection Control Sciences, Department of Pharmacotherapeutics, School of Pharmacy, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Maeda
authors.affiliation: Department of Microbiology, School of Medicine, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Shirakura
authors.affiliation: Division of Clinical Infectious Diseases, Department of Medicine, School of Medicine, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo 142-0064, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Takuma
authors.affiliation: Showa University Hospital, 1-4-5 Hatanodai, Shinagawa, Tokyo, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Ugajin
authors.affiliation: Showa University, Graduate School, 1-4-5 Hatanodai, Shinagawa, Tokyo, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Fukuchi
authors.affiliation: Division of Infection Control Sciences, Department of Pharmacotherapeutics, School of Pharmacy, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Ishino
authors.affiliation: Division of Clinical Infectious Diseases, Department of Medicine, School of Medicine, Showa University, 1-4-5 Hatanodai, Shinagawa, Tokyo 142-0064, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Niki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology* / Q000401:mortality; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology* / Q000401:mortality; D016019:Survival Analysis; D014041:Tokyo; D016896:Treatment Outcome; D014640:Vancomycin / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin
keywords: Bacteraemia; Linezolid; MRSA; Meticillin-resistant Staphylococcus aureus; Minimum inhibitory concentration; Vancomycin