Incidence of antibiotic-resistant Klebsiella pneumoniae and Enterobacter species in freshwater wetlands

Aims: The aim of this study was to assess the incidence of Enterobacteriaceae (potential human and animal pathogens) in wetlands. Methods: Enterobacteriaceae, selected from the sediments and rhizosphere of wetland plant Juncus effusus L., were analysed using classical microbiological methods, API20E, API20NE, fatty acid analyses, and 16S rRNA sequencing. Assessed virulence factors include antibiotic resistance, presence of plasmids and capsules. Results: Klebsiella pneumoniae, Enterobacter cloacae and Enterobacter asburiae, known human pathogens, were identified. K. pneumoniae 16S rRNA gene sequence showed the significant hit (E < 0.001) with the unculturable bacteria obtained from faeces of elderly individuals (accession number AB099804) when Genbank database was used. Ent. asburiae 16S rRNA gene sequence showed the significant hit with (E < 0.001) with the unculturable bacteria obtained from the pig gastrointestinal tract (accession number AF371852). The rate of antibiotic resistance (<50 mug ml(-1)) was high for ampicillin and cephalosporins for the most strains (75.7%) yet low (>10 to 20 mug ml(-1)) for kanamycin, tetracycline and chloramphenicol for all strains tested. Capsules were detected in all investigated strains. PCR detected membrane protein but not chromosomally encoded beta-lactamase. Significance and Impact of the Study: The antibiotic resistance of tested strains and presence of capsules (protect micro-organisms from phagocytosis) suggest that wetland sediments and rhizosphere present a potential reservoirs for enteric human and animal pathogens.