The Prevalence Rate, Pattern of Antibiotic Resistance, and Frequency of Virulence Factors of Pseudomonas aeruginosa Strains Isolated from Fish in Iran

Pseudomonas aeruginosa (P. aeruginosa) is a pathogenic bacterium and one of the seafood's most common spoilage microorganisms. In this study, 470 fish samples collected randomly were evaluated for the presence of P. aeruginosa, antibiotic resistance, and frequency of virulence factors. Isolation of P. aeruginosa from fish samples was performed on cetrimide agar after an initial enrichment. Representative colonies were selected, and biochemical tests were conducted. An antibiotic resistance test was performed using the disk diffusion method. DNA was extracted, and antibiotic resistance genes, as well as virulence genes, were detected using PCR. Fresh fish showed the highest prevalence of P. aeruginosa (5%). No positive samples contaminated with P. aeruginosa were isolated from frozen fish samples. From smoked, salted, and dried fish, two samples (2.85–4%) were contaminated with P. aeruginosa. The antibiotic resistance against meropenem, imipenem, carbapenem, erythromycin, gentamicin, chloramphenicol, and enrofloxacin was 0%. The lowest antibiotic resistance pattern was observed in fresh fish, and the highest was observed in smoked, salted, and dried fish. Respectively, blaTEM, blaCTX-M, and blaSHV were the most abundant genes encoding antibiotic resistance. The most virulence genes were algD, algU, lasB, toxA, exoS, exoT, and apr. This study suggests that raw seafood could be a source of antibiotic-resistant P. aeruginosa and helps to spread resistance genes through the food chain. It seems that cross-contamination in the fishing, transportation, and supply of seafood can cause increased contamination with Pseudomonas aeruginosa in these products. Therefore, the hygienic principles can effectively reduce contamination by P. aeruginosa. Also, the prophylactic use of antibiotics in these products should be controlled.