Isolation of drug-resistant Aeromonas hydrophila from aquatic environments

Abstract

Antibiotic-resistant strains of Aeromonas hydrophila have been isolated from the natural environment in the Chesapeake Bay and areas surrounding Dacca and the Matlab region of Bangladesh. The Bangladesh strains carried resistance to chloramphenicol, streptomycin, and tetracycline, and 57% of them had a multiple streptomycin-tetracycline resistance phenotype correlated with the presence of a large plasmid. The Chesapeake Bay strains were resistant to polymyxin B ane tetracycline, but showed neither multiple resistance nor R-factor carriage. Twenty-five percent of the environmental strains were toxigenic in a Y-1 adrenal cell assay. Toxigenicity showed no positive correlation with drug resistance or with plasmid carriage. Environmental areas of heavy human impact appear to be associated with a higher incidence of antibiotic-resistant strains of aeromonads.

Antimicrobial Susceptibilities of Aeromonas Strains Isolated from Clinical and Environmental Sources to 26 Antimicrobial Agents

“…Susceptibility to tetracycline was high (94.36%), consistent with previous reports from Australia and the United States (18,20). In contrast, tetracycline resistance in up to 49% of isolates has been reported in studies from the Asian region (7,17,19). The three amoxicillin-susceptible isolates described here con- a One hundred nine strains tested.…”

“…Differences in antimicrobial susceptibility between clinical and environmental strains have been described previously (19,20). The resistance observed in environmental aeromonads has been associated with heavily polluted waters as the source of multiple resistance plasmids (13).…”

Incidence, Distribution, and Spread of Tetracycline Resistance Determinants and Integron-Associated Antibiotic Resistance Genes among Motile Aeromonads from a Fish Farming Environment

“…DePaola et al (8) found similarly high proportions of OTCresistant aeromonads from catfish and their environments (58 to 83%), where the drug was routinely used in medicated feed. Other comparable investigations of motile aeromonads from different freshwater environments report considerably lower tetracycline resistance levels (7,10,11,23,28,42). One explanation may be that, once acquired, the resistance genes are maintained within the population, protecting the bacteria from tetracyclines produced by other members of the microflora or residues in agricultural or domestic effluents.…”

“…Water, sediment, and fish samples were examined, and because of their ubiquitous distribution in the freshwater environment, the motile aeromonads were selected as bacterial indicators. In addition, members of the genus Aeromonas readily develop single or multiple antimicrobial resistance phenotypes (10,12,18,(23)(24)(25), and Rplasmids are commonly found (1,3,5,13,19,28). Thus, they were well suited for monitoring the incidence of antibiotic resistance, as well as for investigating the conjugative spread of resistance genes in these settings.…”

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

“…These correlated with previous reports in which the resistance had been determined to cephalosporins with similar patterns as those observed in Aeromonas strains from clinical and environmental origins (Overman & Janda 1999, Castro-Escarpulli et al 2002a. McNicol et al (1980) reported that 57% of the environmental Aeromonas isolates recovered in Chesapeake Bay and areas surrounding Dacca and the Matlab region of Bangladesh were resistant to multiple antibiotis. In our study, no antibiograms similar to those described above were obtained.…”