title: Antimicrobial susceptibility of clinical isolates of Actinomyces and related genera reveals an unusual clindamycin resistance among Actinomyces urogenitalis strains.
abstract: Patterns of antimicrobial susceptibility in Actinomyces and related genera are very limited in the literature. Data of predominant susceptibility profiles could contribute to the establishment of an accurate empirical treatment.
  
  
  
  A total of 113 isolates from clinical samples were included in this study. Each isolate was identified using phenotypic methods and MALDI-TOF/MS. When discrepancies were observed, 16S rRNA gene sequencing was performed. The minimum inhibitory concentrations (MICs) of nine antimicrobial agents (penicillin, ceftriaxone, linezolid, tetracycline, clindamycin, erythromycin, ciprofloxacin, levofloxacin and vancomycin) were tested against 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) and Varibaculum cambriense (n=1).
  
  
  
  All of the isolates were susceptible to penicillin, ceftriaxone, vancomycin and linezolid. Almost all of the A. urogenitalis isolates (8/11) were resistant to clindamycin and showed susceptibility to erythromycin, suggesting an L-phenotype, however no determinants of clindamycin resistance (lnu and lsa genes) were detected by PCR. High MIC values to quinolones were observed in 54/113 isolates (47.8%). All of the A. urogenitalis isolates were highly resistant to ciprofloxacin and levofloxacin.
  
  
  
  These data highlight the importance of ongoing surveillance to provide relevant information for empirical management of infections caused by these organisms.
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina. Electronic address: claudiabar07@gmail.com.
authors.forename: Claudia
authors.initials: C
authors.lastname: Barberis
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Mabel
authors.initials: M
authors.lastname: Budia
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Susana
authors.initials: S
authors.lastname: Palombarani
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Carlos Hernán
authors.initials: CH
authors.lastname: Rodriguez
authors.affiliation: Universidad de Buenos Aires, Facultad de Medicina, Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: María Soledad
authors.initials: MS
authors.lastname: Ramírez
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Barbara
authors.initials: B
authors.lastname: Arias
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Bonofiglio
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Angela
authors.initials: A
authors.lastname: Famiglietti
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Marta
authors.initials: M
authors.lastname: Mollerach
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Marisa
authors.initials: M
authors.lastname: Almuzara
authors.affiliation: Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Carlos
authors.initials: C
authors.lastname: Vay
mesh_terms: D039903:Actinobacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D000196:Actinomycosis / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002981:Clindamycin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D006801:Humans; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D002981:Clindamycin
keywords: Actinomyces spp.; Antimicrobial susceptibility; Clindamycin