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Prevalence, antibiotic resistance, and toxigenic gene profile of the Clostridium difficile isolated from molluscan shellfish

Nayebpour, Farnaz, Rahimi, Ebrahim
Journal of food safety 2019 v.39 no.1 pp. e12586
Clostridium difficile, amoxicillin, antibiotic resistance, bacteria, clams, food pathogens, human population, metronidazole, microbiological quality, moxifloxacin, multigene family, multiple drug resistance, mussels, oysters, polymerase chain reaction, public health, seafoods, shellfish, Iran, Persian Gulf
Clostridium difficile strains are considered as one of the newly borne foodborne pathogens regarding the consumption of seafood products. The present study was done to assess the antibiotic resistance pattern and toxigenic gene profile of the C. difficile strains isolated from shellfish samples. Eight‐hundred and twenty oyster, mussel, cockle, and clam samples were collected and cultured. Clostridium difficile isolates were subjected to polymerase chain reaction disk diffusion. Twenty‐six out of 820 (3.17%) shellfish samples were positive for C. difficile. Mussel (5.00%) and oyster (4.00%) were the most commonly contaminated samples. Clostridium difficile strains exhibited the highest prevalence of resistance against ampicillin (92.30%), penicillin (84.61%), amoxicillin (76.92%), moxifloxacin (65.38%), and metronidazole (57.69%). Prevalence of resistance against more than eight types of antibiotics was 15.38%. TcdA (50%), tcdB (30.76%), and cdtA (30.76%) were the most commonly detected toxigenic genes. Clostridium difficile strains harbored the highest prevalence of tcdA + tcdB (23.07%), tcdA + cdtA (19.23%), tcdB + cdtA (15.38%), and tcdA + tcdB + cdtA (11.53%) gene clusters. Shellfish samples have been considered as a potential source of toxigenic multidrug resistant C. difficile. Simultaneous presence of multiple toxigenic genes in the multidrug resistant C. difficile strains poses an important public health issue regarding the consumption of raw and shellfish. PRACTICAL APPLICATIONS: Due to the high‐consumption rate of molluscan shellfish, they should have a high microbial quality. Clostridium difficile is common foodborne bacteria with an emergence of antibiotic resistance and toxin production. The current research is the first report of the isolation and study the antibiotic resistance and toxigenic gene profile of the C. difficile strains isolated from oyster, mussel, cockle, and clam samples caught from the Persian Gulf, Iran. Results represented that molluscan shellfish samples may act as a reservoir of Clostridium difficile with ability to transfer antibiotic resistance and toxin genes to human population.