Isolation and Characterization of Aeromonas Species Isolated from Food and Diarrhoeagenic Stool in Ibadan Metropolis, Nigeria

Abstract

Aeromonas species has been associated with gastroenteritis which resulted in about 1.3 million deaths of children less than 5 years as of 2008. The ability of Aeromonas species to survive in chlorinated water when they are in biofilms couple with antibiotics resistance and virulence toxins produce call for continuous monitoring of food and diarrhoeagenic stool for Aeromonas species. Cabbage (100), tap water (100) and diarreagenic stool (100) were randomly collected in Ibadan metropolis and analysed for the presence of Aeromonas species using standard method. The isolated Aeromonas species were identified using classical method and confirmed by PCR using 16S rRNA primmer and Random amplified polymorphic DNA (RAPD) analysis. Survival of Aeromonas species in different chlorine concentrations was determined using standard method. Antibiotics susceptibility profiles of the isolates were determine using disc diffusion technique. Data were analysed using one-way ANOVA at α_0.05. Two hundred and twenty nine isolates of Aeromonas were obtained and identified as Aeromonas veronii (23), Aeromonas caviae (29), Aeromonas hydrophilla (52), Aeromonas popoff (15), Aeromonas trota (2), Aeromona schubertii (3), Aeromonas jandaei (16), Aeromonas media (10), Aeromonas salmonicida (28), Aeromonas bestiarum (10) Aeromonas sobriae (20) and A. aquariorum (21). The PCR confirms 10 species as Aeromonas, however RAPD differentiates Aeromonas species and confirms 60 to 100% genetic similarities indicating endemic infection. Aeromonas species was able to survive in most of chlorine concentrations used in this work. All isolates were 100% resistance to ampicillin, amikacin (85%), gentamycin, rifampicin, penicillin, nitrofurantoin (80% each) and nalidixic acid (75%). High multiple antibiotics resistance was observed among Aeromonas species with Minimum inhibitory concentration ranged from 16-512µg/mL for ofloxacin, ciprofloxaxin and tetracycline. Aeromonas species obtained from Cabbage, tap water and diarrhoeagenic stool are multidrug resistance confirming food and water transmission thereby calls for potent therapeutic measures and good manufacturer practices are recommended.

Keywords: Aeromonas spp, multiple antibiotics resistance, Cabbage, water, Diarrhoeagenic stool.