Antimicrobial Susceptibilities of Aeromonas spp. Isolated from Environmental Sources

Abstract

Aeromonas spp. are ubiquitous aquatic bacteria that cause serious infections in both poikilothermic and endothermic animals, including humans. Clinical isolates have shown an increasing incidence of antibiotic and antimicrobial drug resistance since the widespread use of antibiotics began. A total of 282 Aeromonas pure cultures were isolated from both urban and rural playa lakes in the vicinity of Lubbock, Texas, and several rivers in West Texas and New Mexico. Of these, at least 104 were subsequently confirmed to be independent isolates. The 104 isolates were identified by Biolog and belonged to 11 different species. The MICs of six metals, one metalloid, five antibiotics, and two antimicrobial drugs were determined. All aeromonads were sensitive to chromate, cobalt, copper, nickel, zinc, cefuroxime, kanamycin, nalidixic acid, ofloxacin, tetracycline, and sulfamethoxazole. Low incidences of trimethoprim resistance, mercury resistance, and arsenite resistance were found. Dual resistances were found in 5 of the 104 Aeromonas isolates. Greater numbers of resistant isolates were obtained from samples taken in March versus July 2002 and from sediment versus water. Plasmids were isolated from selected strains of the arsenite-and mercury-resistant organisms and were transformed into Escherichia coli XL1-Blue MRF. Acquisition of the resistance phenotypes by the new host showed that these resistance genes were carried on the plasmids. Mercury resistance was found to be encoded on a conjugative plasmid. Despite the low incidence of resistant isolates, the six playa lakes and three rivers that were sampled in this study can be considered a reservoir for antimicrobial resistance genes.

Impact of treated wastewater on organismic biosensors at various levels of biological organization

“…The incidence of resistance of environmental Aeromonas spp. samples to SMX in this work was significantly higher than in comparable studies (Imzlin et al, 1996;Kampfer et al, 1999;Huddleston et al, 2006), most likely because our isolates have previously been exposed to antibiotics and chemotherapeutics due to a hospital discharge waters going through the WWTP. Possibly for the same reason 11 % of water and sludge aeromonads (3 isolates) were resistant to oxytetracycline and erythromycin.…”

“…Mesophilic aeromonads persist in most aquatic environments, including chlorinated drinking water, raw sewage, groundwater and both polluted and unpolluted streams and rivers (Huddleston et al, 2006). Bearing in mind that most of the retrieved bacteria from fish, water and sludge in this work were aeromonads, it is important to stress that aeromonads have been associated with bacterial zoonoses.…”

“…Relatively low levels of fecal coliforms could nevertheless accumulate in the fish digestive system, posing a risk of transmission to consumers by cross-contamination of tissues, in case of inadequate hygiene standards in fish preparation (El-Shafai et al, 2004;Harnisz and Tucholski, 2010) Goni-Urriza et al, 2000;Lehane and Rawlin, 2000;Huddleston et al, 2006;. With the popularity of recreational fishing in watersheds downstream from the investigated WWTP, medical personnel may expect more aeromonad-related infections, whereas their diagnosis and treatment may be difficult, particularly taking into consideration the emerging antibiotic resistance of fish pathogens.…”

“…salmonicida is a fish pathogen . As contact-borne, A. hydrophyila, A. sobria, and A. caviae 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 26 may cause fish handler disease through skin wound infections and systemic infections, while as food-borne, A. hydrophyila may lead to gastroenteritis, diarrhoea and systemic infections Goni-Urriza et al, 2000;Lehane and Rawlin, 2000;Huddleston et al, 2006;. With the popularity of recreational fishing in watersheds downstream from the investigated WWTP, medical personnel may expect more aeromonad-related infections, whereas their diagnosis and treatment may be difficult, particularly taking into consideration the emerging antibiotic resistance of fish pathogens.…”

“…With the popularity of recreational fishing in watersheds downstream from the investigated WWTP, medical personnel may expect more aeromonad-related infections, whereas their diagnosis and treatment may be difficult, particularly taking into consideration the emerging antibiotic resistance of fish pathogens. Environmental contamination with antimicrobials and other antibiotic substances is an important contributor to the survival and spread of antibiotic resistance genes (Huddleston et al, 2006), particularly through spread of resistance plasmids between unrelated bacteria (Kostich and Lazorchak, 2008).…”