title: Susceptibility to Aminoglycosides and Distribution of aph and aac(3)-XI Genes among Corynebacterium striatum Clinical Isolates.
abstract: Corynebacterium striatum is an opportunistic pathogen, often multidrug-resistant, which has been associated with serious infections in humans. Aminoglycosides are second-line or complementary antibiotics used for the treatment of Corynebacterium infections. We investigated the susceptibility to six aminoglycosides and the molecular mechanisms involved in aminoglycoside resistance in a collection of 64 Corynebacterium striatum isolated in our laboratory during the period 2005-2009. Antimicrobial susceptibility was determined using E-test. The mechanisms of aminoglycoside resistance were investigated by PCR and sequencing. The 64 C. striatum were assessed for the possibility of clonal spreading by Pulsed-field Gel Electrophoresis (PFGE). Netilmicin and amikacin were active against the 64 C. striatum isolates (MICs90 = 0.38 and 0.5 mg/L, respectively). Twenty-seven of the 64 C. striatum strains showed a MIC90 for kanamycin > 256 mg/L, and 26 out the 27 were positive for the aph(3')-Ic gene. Thirty-six out of our 64 C. striatum were streptomycin resistant, and 23 out of the 36 carried both the aph(3")-Ib and aph(6)-Id genes. The gene aac(3)-XI encoding a new aminoglycoside 3-N acetyl transferase from C. striatum was present in 44 out of the 64 isolates, all of them showing MICs of gentamicin and tobramycin > 1 mg/L. CS4933, a C. striatum showing very low susceptibility to kanamycin and streptomycin, contains an aminoglycoside resistance region that includes the aph(3')-Ic gene, and the tandem of genes aph(3")-Ib and aph(6)-Id. Forty-six major PFGE types were identified among the 64 C. striatum isolates, indicating that they were mainly not clonal. Our results showed that the 64 clinical C. striatum were highly resistant to aminoglycosides and mostly unrelated.
authors.affiliation: Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Herrera Oria s/n, Santander, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Navas
authors.affiliation: Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IDIVAL, Avda. de Valdecilla s/n, Santander, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Fernández-Martínez
authors.affiliation: Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IDIVAL, Avda. de Valdecilla s/n, Santander, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Salas
authors.affiliation: Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IDIVAL, Avda. de Valdecilla s/n, Santander, Spain.
authors.forename: María Eliecer
authors.initials: ME
authors.lastname: Cano
authors.affiliation: Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Herrera Oria s/n, Santander, Spain.|Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IDIVAL, Avda. de Valdecilla s/n, Santander, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D003352:Corynebacterium / Q000187:drug effects* / Q000235:genetics; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology
chemical_list: D000617:Aminoglycosides