Prevalence and antibiotic resistance of Aeromonas hydrophila and Staphylococcus aureus isolated from seafood in Egypt

Objective: To investigate prevalence of Aeromonas. hydrophila and Staphylococcus aureus in seafood, detect the consistent virulence genes and assess the antimicrobial susceptibility.
Design: Observational study.
Samples: 280 marketed seafood samples (178 shrimp, 54 oysters, 26 crabs, 18 squid, and 4 octopuses).
Procedures: Isolation and identification of Aeromonas hydrophila and Staphylococcus aureus were performed using conventional methods. The identified isolates were examined for virulence genes (aer and hly genes for A. hydrophila as well as nuc and sea genes for S. aureus) and antimicrobial susceptibility.
Results: A. hydrophila was isolated from 40 of the 280 seafood samples (14.3%), with the highest prevalence (22.2%) in oyster, whereas S. aureus occurred in 50 samples (17.9%) with the highest prevalence (20.2%) in shrimp. Moreover, aer and hly genes were detected in all A. hydrophila isolates, and nuc gene in all S. aureus strains, whereas staphylococcal enterotoxin A (sea) gene in 44% S. aureus strains. A. hydrophila strains were resistant to amoxicillin (100%), ceftriaxone (80%), chloramphenicol (77.5%), and trimethoprim-sulfamethoxazole (65%), whereas S. aureus strains showed high resistance to penicillin (86%), amoxicillin-clavulanic acid (72%), and trimethoprim-sulfamethoxazole (58%). Multidrug resistance (MDR) to more than two classes of antibiotics was found in 77.5% of A. hydrophila strains and 66% of S. aureus isolates.
Conclusion and clinical relevance : Our data highlights importance of awareness of virulent strains of MDR A. hydrophila and S. aureus of seafood in Egypt. Consequently, continuous surveillance of bacteria in seafood with strong focus on antibiotic resistance characteristics should be considered in further studies.