Phenotypic and genetic analysis of Enterobacter spp. from a Brazilian oligotrophic freshwater lake.
We characterized a population of Enterobacter spp. of the Enterobacter cloacae complex isolated from an oligotrophic lake; most isolates were identified as E. cloacae. Fingerprinting polymerase chain reaction (PCR), along with morphological, biochemical, physiological, and plasmid profiles analyses, including antimicrobial susceptibility testing, were performed on 22 environmental isolates. Misidentification occurred when using the API 20E identification system. Analysis of 16S rDNA sequences confirmed the close relatedness between species of the E. cloacae complex. The tDNA PCR allowed the differentiation and identification of the E. cloacae isolates. Evaluation of genetic diversity by 16S rDNA sequence, tDNA, internal transcribed spacers, and enterobacterial repetitive intergenic concensus profiles revealed nearly identical isolates, although they exhibited different physiological and antimicrobial resistance profiles. Among the Enterobacter isolates, 96% were resistant to at least one antimicrobial; multiple resistance was also found at a high frequency (86%). The antimicrobials against which resistance was found most frequently were beta-lactams, chloramphenicol, and streptomycin. Plasmids were found in 21 of the 22 Enterobacter isolates. This confirms the conception that antibiotic resistance can occur in oligotrophic freshwater lake bacteria, which has important implications for public health.
Pontes
Daniela Santos
DS
Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte-MG, Brazil.
Lima-Bittencourt
Cláudia Iracema
CI
Azevedo
Marcela Santiago Pacheco
MS
Chartone-Souza
Edmar
E
Nascimento
Andréa Maria Amaral
AM
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D001938:Brazil; D004754:Enterobacter / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D005618:Fresh Water / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S