title: In vitro synergy of oxacillin and gentamicin against coagulase-negative staphylococci from blood cultures of neonates with late-onset sepsis.
abstract: Coagulase-negative staphylococci (CoNS) are the leading cause of late-onset sepsis (LOS) in neonates. Increasing resistance of CoNS to beta-lactams and aminoglycosides has led to widespread use of vancomycin, which in turn may lead to resistance to vancomycin. Thus, combination therapy of LOS has been advocated. We aimed to determine the interaction of oxacillin and gentamicin against CoNS. In 2005, 34 isolates of oxacillin- and gentamicin-resistant CoNS were obtained from blood samples of neonates with LOS. Combination effect was tested using the checkerboard method, E-test with the other antibiotic incorporated in the medium (E-test-1) and two E-test strips placed in a cross-formation (E-test-2). Of 34 isolates 61.8%, 53% and 73.5% revealed synergy or an additive effect when tested by the checkerboard method, E-test-1 and E-test-2, respectively. Results of all three tests were concordant for six (17.6%) isolates, four showing synergy, and two indifference. Our in vitro results support that combination therapy with penicillinase-resistant penicillin and aminoglycoside can be an alternative to vancomycin.
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Brilene
authors.forename: Hiie
authors.initials: H
authors.lastname: Soeorg
authors.forename: Merilin
authors.initials: M
authors.lastname: Kiis
authors.forename: Epp
authors.initials: E
authors.lastname: Sepp
authors.forename: Siiri
authors.initials: S
authors.lastname: Kõljalg
authors.forename: Krista
authors.initials: K
authors.lastname: Lõivukene
authors.forename: Marika
authors.initials: M
authors.lastname: Jürna-Ellam
authors.forename: Jelena
authors.initials: J
authors.lastname: Kalinina
authors.forename: Jelena
authors.initials: J
authors.lastname: Stšepetova
authors.forename: Tuuli
authors.initials: T
authors.lastname: Metsvaht
authors.forename: Irja
authors.initials: I
authors.lastname: Lutsar
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003030:Coagulase / Q000172:deficiency / Q000235:genetics; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D018805:Sepsis / Q000382:microbiology; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003030:Coagulase; D003470:Culture Media; D005839:Gentamicins; D014640:Vancomycin; D010068:Oxacillin
keywords: In vitro synergy; coagulase-negative staphylococci; gentamicin; oxacillin