Phenotypic and genotypic characterization of tetracycline- and oxytetracycline-resistant Aeromonas hydrophila from cultured channel catfish (Ictalurus punctatus) and their environments

Abstract

Oxytetracycfine-resistant (OTcr) and tetracycline-resistant (Tc') Aeromonas hydrophila were isolated commonly from catfish intestinal contents and the water and sediment of catfish culture ponds, but less frequently in market catfish. Isolates demonstrated two resistance phenotypes, Tcr OTcr and Tcs OTcr, when plated directly on to MacConkey agar containing 30 Fig of tetracycline or oxytetracycline per ml. Tcs OTcr isolates expressed Tcr after induction by 1 h of growth in tryptic soy broth containing 1 p.g of tetracycline per ml, Over 90% of the resistant aeromonads hybridized with DNA probes for class A or class E Tcr determinants; class E was twice as prevalent as class A. The distribution of class A and E Tcr determinants varied with the Tcr phenotypes. Prior to induction, 86% of isolates with class A determinants were Tcr as well as OTcr, while only

PCR typing of tetracycline resistance determinants (Tet A–E) in Salmonella enterica serotype Hadar and in the microbial community of activated sludges from hospital and urban wastewater treatment facilities in Belgium

“…Previous environmental studies have documented various distributions among tetracycline determinants. Hybridizations performed with DNA probes for Tet A and Tet E on environmental tetracycline-resistant isolates were ¢rst conducted by DePaola et al [15]. It was shown that over 90% of Tc R Aeromonas strains isolated from cat¢sh intestinal contents and the water and sediment of cat¢sh culture ponds in the southeastern USA were positive for both determinants; Tet E was twice as prevalent as Tet A.…”

“…While the distribution of e¥ux-mediated tetracycline determinants in clinical isolates has been extensively studied [10^14], their prevalence and distribution in environmental habitats has received less attention. Environmental studies on the distribution of tetracycline resistance determinants were con¢ned to cat¢sh culture ponds [15,16] and marine sediments [17]. All were conducted with the ¢ve most widely distributed determinants among aerobic, enteric Gram-negative bacteria, namely, Tet A^E.…”

Prevalence of tet gene and complete genome sequencing of tet gene-encoded plasmid (pAHH01) isolated from Aeromonas species in South Korea

“…The rep gene was related to the plasmid pAsal1, pAsal2 and pAsa3, the relB ⁄ E gene was related to the plasmid pAsal2, the mob gene was related to the plasmid pAsal1, pAsal2 and pAsa3, and the tet(E) and tet(R) genes were related to the plasmid 4. motile Aeromonas spp. (Aoki and Takahashi 1987;DePaola et al 1988;Adams et al 1998;Goni-Urriza et al 2000). Twelve out of 13 strains that carried at least one of these three tet genes (tetA, tetD and tetE) were resistant to tetracycline based on the MIC.…”

Diversity and characterization of oxytetracycline-resistant bacteria associated with non-native species, white-leg shrimp (Litopenaeus vannamei), and native species, black tiger shrimp (Penaeus monodon), intensively cultured in Thailand

“…grow-out ponds, ranging from 0AE008 to 52%. Many studies suggest a correlation between increased bacterial resistance levels on fish farms and the antibiotics used at the farms (DePaola et al 1988;Guardabassi et al 2000). Tendecia and de la Peña (2001) reported a consistent increase in percentage of resistant bacteria with administration of antibiotics to shrimp ponds.…”