Antimicrobial resistance in bacteria isolated from aquaculture sources in Australia

Abstract

Aims: To carry out a preliminary assessment of the occurrence of resistance to antimicrobials in bacteria that has been isolated from a variety of aquaculture species and environments in Australia. Method and Results: A total of 100 Gram‐negative (Vibrio spp. and Aeromonas spp. predominantly) and four Gram‐positive bacteria isolated from farmed fish, crustaceans and water from crab larval rearing tanks were obtained from diagnostic laboratories from different parts of Australia. All the isolates were tested for sensitivity to 19 antibiotics and Minimal Inhibitory Concentrations were determined by the agar dilution method. Plasmid DNA was isolated by the alkali lysis method. Resistance to ampicillin, amoxycillin, cephalexin and erythromycin was widespread; resistance to oxytetracycline, tetracycline, nalidixic acid and sulfonamides was common but resistance to chloramphenicol, florfenicol, ceftiofur, cephalothin, cefoperazone, oxolinic acid, gentamicin, kanamycin and trimethoprim was less common. All strains were susceptible to ciprofloxacin. Multiple resistance was also observed and 74·4% of resistant isolates had between one and ten plasmids with sizes ranging 2–51 kbp. Conclusions: No antibiotics are registered for use in aquaculture in Australia but these results suggest that there has been significant off‐label use. Significance and impact of study: Transfer of antibiotic resistant bacteria to humans via the food chain is a significant health concern. In comparison with studies on terrestrial food producing animals, there are fewer studies on antibiotic resistance in bacteria from aquaculture enterprises and this study provides further support to the view that there is the risk of transfer of resistant bacteria to humans from consumption of aquaculture products. From the Australian perspective, although there are no products registered for use in aquaculture, antimicrobial resistance is present in isolates from aquaculture and aquaculture environments.

Bacterial Flora and Antimicrobial Resistance in Raw Frozen Cultured Seafood Imported to Denmark

“…Previous studies on antimicrobial resistance in seafood have almost entirely determined resistance for other, mainly zoonotic, bacterial pathogens, including Vibrio (1,3,11,16,24,32,38), Aeromonas (1,3,25,28,42), Salmonella (16,32), and the fecal indicator E. coli (1,16,21,34). Little is known about the normal bacterial flora in cultured shrimp and fish at the point of harvest or in the final processed products.…”

Sensibilidade antimicrobiana de bactérias isoladas de Jundiá (Rhamdia quelen)

“…A resistência aos antimicrobianos é um evento bastante estudado em peixes e seu ambiente (Saavedra et al 2004, Hatha et al 2005. Em muitos casos, esta resistência pode ser disseminada por plasmídeos (Akinbowale et al 2006). Segundo Hatha et al (2005), isolados de Aeromonas spp.…”

“…Todavia, tem seu emprego limitado, pois se utilizados de uma forma indiscriminada e abusiva podem acarretar no desenvolvimento de uma microbiota resistente, através da troca de plasmídeos de resistência em infecções cruzadas e inativação dos agentes antimicrobianos pelo pH da água (Akinbowale et al 2006, Cabello 2006. A contaminação de fontes de água com resíduos de antibióticos, pode ser responsável por infecções de difícil tratamento e constituir um risco a saúde pública (Dixow & Issvoran 1993, Schmidt et al 2000, Saavedra et al 2004.…”

Prevalence of Biofilm Formation and Wide Distribution of Virulence Associated Genes among Vibrio spp. Strains Isolated from the Monastir Lagoon, Tunisia

“…isolated from Indian coastal and brackish areas. Another study, showed that Vibrio isolates recovered from aquaculture structure expressed moderate resistance to chloramphenicol, gentamycin, tetracyclin and erythromycin (Akinbowale et al, 2006).…”