Antimicrobial susceptibility of clinical isolates of Actinomyces and related genera reveals an unusual clindamycin resistance among Actinomyces urogenitalis strains.

BARBERIS C; BUDIA M; PALOMBARANI S; RODRIGUEZ CH; ARIAS B; RAMIREZ MS; BONOFIGLIO L; FAMIGLIETTI A; MOLLERACH M; ALMUZARA M; VAY C

JOURNAL OF GLOBAL ANTIMICROBIAL RESISTANCE

Elsevier

Año: 2017 vol. 8 p. 115 - 120

2213-7165

IntroductionPatterns of antimicrobial susceptibility in Actinomyces and related genera are very limited in literature. Data of predominant susceptibility profiles could contribute in the establishment of an accurate empiric treatment.Materials and MethodsA total of 113 isolates from clinical samples were included. Each isolate was identified using phenotypic methods and MALDI-TOF MS. When discrepancies were observed, 16s rRNA gene sequencing was performed. The Minimum Inhibitory Concentration (MICs) of nine antimicrobial agents (penicillin, ceftriaxone, linezolid, tetracycline, clindamycin,erythromycin, ciprofloxacin, levofloxacin and vancomycin) were tested in the species Actinotignum schaalii (n= 23), Actinomyces turicensis (n=18), Actinomyces europaeus (n= 13), Actinomyces naeslundii/Actinomyces viscosus group (n= 12), Actinomyces urogenitalis (n= 11), Actinomyces radingae (n= 11), Actinomyces neuii (n= 9), Actinomyces odontolyticus (n=8), Bifidobacterium scardovii (n= 3), Actinomyces graevenitzii (n= 2),Alloscardovia omnicolens (n= 2), Varibaculum cambriense (n= 1).ResultsAll the isolates were susceptible to penicillin, ceftriaxone, vancomycin,and linezolid. Almost all the A. urogenitalis isolates (8/11) were resistant to clindamycin and showed susceptibility to erythromycin suggesting L-phenotype however no determinants of clindamycin resistance genes, lnu and lsa, were detected by PCR. High MICs levels to quinolones were observed in 54/113 isolates (47.8%). All the A. urogenitalisisolates were highly resistant to ciprofloxacin and levofloxacin.ConclusionsThese data highlight the importance of ongoing surveillance to provide relevant information for empiric management of infections caused by these organisms.