Phenotypic and genetic analysis of Enterobacter spp. from a Brazilian oligotrophic freshwater lake

• Published in: Canadian journal of microbiology Vol. 53; no. 8; pp. 983 - 991
• Main Authors: Pontes, Daniela Santos, Lima-Bittencourt, Cláudia Iracema, Azevedo, Marcela Santiago Pacheco, Chartone-Souza, Edmar, Nascimento, Andréa Maria Amaral
• Format: Journal Article
• Language: English
• Published: Ottawa, ON National Research Council of Canada 01.08.2007; NRC Research Press; Canadian Science Publishing NRC Research Press
• Subjects: Animal, plant and microbial ecology; Anti-Bacterial Agents - pharmacology; Antibiotic resistance; Antimicrobial agents; antimicrobial resistance; Bacteria; Bacterial Typing Techniques; Bacteriology; Biological and medical sciences; Brazil; caractérisation phénotypique; Drug resistance in microorganisms; empreinte PCR; Enterobacter; Enterobacter - classification; Enterobacter - drug effects; Enterobacter - genetics; Enterobacter cloacae; Enterobacteriaceae; Evaluation; Fresh water; Fresh Water - microbiology; Freshwater; Freshwater ecology; Freshwater lakes; Fundamental and applied biological sciences. Psychology; Genetic diversity; Genetics; Genotype & phenotype; Identification and classification; lac d'eau douce oligotrophe; Lake ecology; Lakes; Microbial ecology; Microbial genetics; Microbial Sensitivity Tests; Molecular Sequence Data; oligotrophic freshwater lake; Oligotrophic lakes; PCR fingerprint; Phenotype; phenotypic characterization; Phylogeny; Physiology; Polymerase Chain Reaction; Public health; RNA, Ribosomal, 16S - genetics; résistance antimicrobienne; Sequence Analysis, DNA; Various environments (extraatmospheric space, air, water); South America; Brazil; America; Characterization; Freshwater environment; Polymerase chain reaction; Resistance; Enterobacter; Bacteria; Population; Lacustrine environment; Oligotrophy; Enterobacteriaceae
• ISSN: 0008-4166; 1480-3275
• DOI: 10.1139/W07-060

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 β-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.