Genotypic Identification and Evaluation of Several Selective Media for Recovery of Aeromonas spp. from Different Sources

A total number of 250 samples of tilapia Niloticus fish (50), mugil cephalus fish (50), drinking water (25 tap water in addition to 25 bottled mineral water), pond water (50) and childhood diarrhea (50) were collected from Suez canal area and these samples were cultured on several selective media, The isolation rate of Aeromonas spp. from all samples using enrichment technique on starch ampicillin agar (SAA), Rimler-shotts medium (RS), Blood ampicillin agar (BAA) & MacConkey ampicillin agar (MAA) were (51.2%), (45.2%), (38.8%) and (31.6%) respectively. The incidence and distribution of Aeromonads from different sources of 250 samples (tilapia Niloticus fish, mugil cephalus fish, drinking tap water, bottled mineral water, pond water and childhood diarrhea were 44 (88%), 33 (66%), 4 (16)%, 0 (0%), 42 (84%) and 5 (10%) respectively. The total number of Aeromonas isolates from 250 examined samples were 260 isolates that were biochemically identified into 4 biotypes as 136 (52.31%) A. hydrophila, 81 (31.15%) A. sobria, 34 (13.08%) A. caviae and 9 (3.46%) A. schubertii. The highest prevalence isolated of Aeromonas spp. were A. hydrophila followed by A. sobria, A. caviae and A. schubertii. Results of antibiogram of isolated Aeromonas spp. demonstrated that all tested Aeromonas isolates were resistant to Erythromycin, Sulphamethoxazol-Trimethoprim beside Ampicillin, and while the highest degree of sensitivity towards Ciprofloxacin, Norfloxacin, Amikacin and Gentamicin. Molecular typing of Aeromonas isolates by Polymerase chain reaction technique to determine of 16SrRNA gene that present in all examined isolates of Aeromonas were (100%), and 2 virulence genes were found: aerolysin gene by a percentage of (83.3%) ,and hemolysin gene by a percentage of (8.3%) which present only in A. schubertii.