Antimicrobial Susceptibility of Clinical Oral Isolates of Actinomyces spp.

Alexandra Wolff,Arne C. Rodloff,Toralf Borgmann,Catalina-Suzana Stingu,Paul Vielkind

doi:10.3390/microorganisms10010125

Abstract

Actinomyces species play an important role in the pathogenesis of oral diseases and infections. Susceptibility testing is not always routinely performed, and one may oversee a shift in resistance patterns. The aim of the study was to analyze the antimicrobial susceptibility of 100 well-identified clinical oral isolates of Actinomyces spp. against eight selected antimicrobial agents using the agar dilution (AD) and E-Test (ET) methods. We observed no to low resistance against penicillin, ampicillin-sulbactam, meropenem, clindamycin, linezolid and tigecycline (0–2% ET, 0% AD) but high levels of resistance to moxifloxacin (93% ET, 87% AD) and daptomycin (83% ET, 95% AD). The essential agreement of the two methods was very good for benzylpenicillin (EA 95%) and meropenem (EA 92%). The ET method was reliable for correctly categorizing susceptibility, in comparison with the reference method agar dilution, except for daptomycin (categorical agreement 87%). Penicillin is still the first-choice antibiotic for therapy of diseases caused by Actinomyces spp.

Highlights

Clinical Oral Isolates of ActinomycesActinomyces species are Gram-positive, anaerobic bacteria that are colonizing the skin, gastrointestinal and genitourinary tract
Categorical agreement (CA), very major error (VME), major error (ME) and minor error of the ETest (ET) minimum inhibitory concentration (MIC) compared to the agar dilution (AD) MICs of the selected antimicrobials for 100 isolates of Actinomyces spp. using EUCAST breakpoints or ECOFFS (v10.2) are shown in the E-Test method did not meet the criteria for a reasonable susceptibility testing system for this antibiotic
Isolates against eight antimicrobial agents tested by the E-Test (ET) and agar dilution (AD) methods, using EUCAST breakpoints or ECOFFS (v10.2)

Summary

Introduction

Actinomyces species are Gram-positive, anaerobic bacteria that are colonizing the skin, gastrointestinal and genitourinary tract They play an important role in the maturation of dental plaque and pathogenesis of periodontitis [1,2,3,4]. They are associated with infections such as actinomycosis, cerebral or oral abscesses, infections of the eyes, ear, nose and throat, and pulmonary infections [5,6,7,8,9,10,11,12,13,14,15]. The clinical significance of many newly described Actinomyces spp. has yet to be proven, but some species are possibly associated with polymicrobial infections in superficial soft-tissue abscesses [24,25,26]

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