Journal Article

Antimicrobial susceptibility testing of <i>Actinomyces</i> species with 12 antimicrobial agents

A. J. Smith, V. Hall, B. Thakker and C. G. Gemmell

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 2, pages 407-409
Published in print August 2005 | ISSN: 0305-7453
Published online June 2005 | e-ISSN: 1460-2091 | DOI:
Antimicrobial susceptibility testing of Actinomyces species with 12 antimicrobial agents

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  • Medical Oncology
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Objective: This study was conducted to assess the susceptibility of human clinical isolates of Actinomyces species to 12 antimicrobial agents.

Methods: Human clinical isolates of Actinomyces spp. were collected from stored collections held at the Microbiology Department, Edinburgh University, Anaerobe Reference Laboratory, Cardiff, Glasgow Dental Hospital and Glasgow Royal Infirmary. Each isolate was identified by restriction analysis of amplified 16S ribosomal DNA. MICs of 12 antibiotics comprising benzyl penicillin, amoxicillin, ceftriaxone, linezolid, tetracycline, deoxycycline, clindamycin, erythromycin, clarithromycin, ciprofloxacin, meropenem and piperacillin/tazobactam for 87 strains of Actinomyces species were obtained by Etest methodology.

Results: The Actinomyces species identified for this study comprised: Actinomyces israelii, Actinomyces gerencseriae, Actinomyces turicensis, Actinomyces funkei, Actinomyces graevenitzii and Actinomyces europaeus. All isolates were susceptible to penicillin and amoxicillin. All but one strain of A. turicensis was susceptible to linezolid. A number of A. europaeus and A. graevenitzii isolates were resistant to ceftriaxone and piperacillin/tazobactam. A number of isolates of A. turicensis and A. europaeus also demonstrated resistance to erythromycin. All Actinomyces species tested appeared resistant to ciprofloxacin.

Conclusions: Actinomyces species appear to be susceptible to a wide range of β-lactam agents and these, when combined with β-lactamase inhibitors, should be regarded as agents of first choice. Ciprofloxacin performed poorly. Tetracyclines also demonstrated poor performance. This is the first study of antimicrobial susceptibilities for a number of accurately identified clinical isolates of Actinomyces spp. There are a number of species differences in susceptibility profiles to the antimicrobials tested, suggesting that accurate identification and speciation may have an impact on clinical outcome.

Keywords: Actinomyces israelii; Actinomyces gerencseriae; Actinomyces turicensis; Actinomyces funkei; Actinomyces graevenitzii; Actinomyces europaeus; antimicrobial susceptibility

Journal Article.  1512 words. 

Subjects: Medical Oncology ; Critical Care

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