PREVALENCE, ANTIBIOGRAM AND MOLECULAR CHARACTERIZATION OF Aeromonas hydrophila ISOLATED FROM FROZEN FISH MARKETED IN EGYPT

Abstract

Fish is one of the most important foods because of its high nutritional value, high palatability and easy digestion. On the same time, it acts as a vehicle for many types of pathogenic microorganisms especially Aeromonas spp., which results in public health hazards. Therefore, the present study was conducted to evaluate the prevalence of Aeromonas spp. in frozen fish (mackerel, herrings and fish fillets) marketed in Zagazig city, Sharkia Governorate, Egypt. In addition, multiplex PCR was done to detect some virulence-associated genes in A. hydrophila isolates. Furthermore, antimicrobial susceptibility testing of A. hydrophila isolates to the commonly used antimicrobials in Egypt including cephalothin, ampicillin, chloramphenicol, sulphamethoxazol, oxytetracycline, cloxacillin, gentamicin, kanamycin, amikacin, ciprofloxacin, cefotaxime, erythromycin, streptomycin and neomycin was conducted using the disc diffusion method. The achieved results indicated contamination of frozen fish with different species of Aeromonas such as A. veronii, A. sobria, A. caviae and A. hydrophila. A. veronii was the predominant species isolated from the examined fish; its prevalence rates in mackerel, fish fillets and herrings were 62.5, 50 and 45%, respectively. A. sobria came second; it was isolated only from herrings (30%) and fish fillets (16.7%). The prevalence rates of A. hydrophila in mackerel, fillets and herrings were 12.5, 33.3 and 10%, respectively; while A. caviae was isolated only from mackerel (25%) and herrings (15%). The isolated A. hydrophila harbored some virulence attributes such as aerolysin (aerA) and haemolysin (ahh1). A. hydrophila isolates were resistant to different antimicrobial agents used in Egypt including cloxacillin, erythromycin and streptomycin (100% each); cefotaxime and sulphamethoxazol (80% each); and cephalothin, chloramphenicoland oxytetracycline (60% each); while it was sensitive to ampicillin (80%) and gentamicin (60%). Therefore, hygienic measures should be adopted to control the microbial contamination either in the aquatic environment or in fish markets. Key words: fish; A. hydrophila ; virulence genes; antibiotic sensitivity