Objective: Post-harvest shrimp losses are a big problem due to the proliferation of spoilage bacteria. Presence and multiplication of these bacteria promotes the emergence of food-borne diseases. This study was carried out to characterize some spoilage bacteria from tropical brackish water shrimps and black tiger shrimps stored in ambient temperature (25 °C).
Results: 22 isolates of Bacillus spp; 09 isolates of Coagulase Negative Staphylococci (CNS) and 04 isolates of enterobacteria such as Pantoea spp (01); Serratia plymutica (01) and Serratia rubidaea (02) have been identified. Resistance and virulence genes were then detected. All isolates expressed resistance to at least three of antibiotics tested. 03 isolates of enterobacteria were susceptible to cetfazidim and amoxicillin-clavulanic acid. Bacillus spp showed total susceptibility to cefixim, ertapenem and cetfazidim. Staphylococci were susceptible to clindamycin. Pantoea spp was resistant to all antibiotics but exhibited intermediate susceptibility to amoxicillin-clavulanic acid. 04 isolates of Staphylococci were positive to mecA resistances genes. All the enterobacteria harbor no tetracycline resistance genes. All the isolates of Bacillus exhibited the presence of enterotoxin genes. Also, a high prevalence of 21 isolates to hemolytic enterotoxins was noted. 17 isolates from them kept ability to cell-lyse factor production like sphingomyelinase activities. The majority of Bacillus isolates identified by the present study poses a potential risk of food poisoning due to the prevalence of toxin genes found.
Keywords: Bacillus; Enterotoxins; Resistance genes; Shrimps; Spoilage.