title: Characterization of antibiotic resistance in Listeria spp. isolated from slaughterhouse environments, pork and human infections.
abstract: BACKGROUND
  Listeria species are susceptible to most antibiotics. However, over the last decade, increasing reports of multidrug-resistant Listeria spp. from various sources have prompted public health concerns. The objective of this study was to characterize the antibiotic susceptibility of Listeria spp. and the genetic mechanisms that confer resistance.
  
  
  METHODS
  Forty-six Listeria spp. isolates were studied, and their minimal inhibitory concentrations of antibiotics were determined by microdilution using Sensititre standard susceptibility MIC plates. The isolates were screened for the presence of gyrA, parC, lde, lsa(A), lnu(A), and mprF by PCR, and the amplified genes were sequenced.
  
  
  RESULTS
  All isolates were susceptible to penicillin, ampicillin, tetracycline, erythromycin, and carbapenems. Resistance to clindamycin, daptomycin, and oxacillin was found among L. monocytogenes and L. innocua, and all species possessed at least intermediate resistance to fluoroquinolones. GyrA, parC, and mprF were detected in all isolates; however, mutations were found only in gyrA sequences. A high daptomycin MIC, as reported previously, was observed, suggesting an intrinsic resistance of Listeria spp. to daptomycin.
  
  
  CONCLUSIONS
  These results are consistent with reports of emerging resistance in Listeria spp. and emphasize the need for further genotypic characterization of antibiotic resistance in this genus.
authors.affiliation: Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, Brasil. luzanolli@gmail.com.
authors.forename: Luisa Z
authors.initials: LZ
authors.lastname: Moreno
authors.forename: Renata
authors.initials: R
authors.lastname: Paixão
authors.forename: Débora D S
authors.initials: DD
authors.lastname: Gobbi
authors.forename: Daniele C
authors.initials: DC
authors.lastname: Raimundo
authors.forename: Thais P
authors.initials: TP
authors.lastname: Ferreira
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Moreno
authors.forename: Ernesto
authors.initials: E
authors.lastname: Hofer
authors.forename: Cristhiane M F
authors.initials: CM
authors.lastname: Reis
authors.forename: Glavur R
authors.initials: GR
authors.lastname: Matté
authors.forename: Maria H
authors.initials: MH
authors.lastname: Matté
mesh_terms: D000003:Abattoirs; D000667:Ampicillin / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology; D002981:Clindamycin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D017576:Daptomycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D024841:Fluoroquinolones / Q000494:pharmacology; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D008087:Listeria / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology; D013552:Swine; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D024841:Fluoroquinolones; D002981:Clindamycin; D004917:Erythromycin; D000667:Ampicillin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D013752:Tetracycline; D017576:Daptomycin; D010068:Oxacillin