Presence of toxigenic Clostridioides (Clostridium) difficile in edible bivalve mollusks in Spain

Abstract

Clostridioides difficile reservoirs other than humans are becoming increasingly recognized, and the occurrence of the pathogen in shellfish raises concern because spores can survive cooking temperature and edible bivalve mollusks are often consumed raw or poorly cooked. This study was conducted to determine the occurrence of pathogenic C. difficile in retail bivalve mollusks. The microbiological quality of samples was also checked through the isolation of Salmonella spp. and Escherichia coli. We analyzed 129 mollusk samples from different fishmongers and grocery stores in Murcia. C. difficile was isolated from 8.53% (11/129) of the mollusks investigated. Four C. difficile isolates harbored genes for the production of toxin A and B. Salmonella spp . were not isolated from any sample and E. coli was isolated from 1.55% (2/129) of the samples, in both cases in accordance with the current legal requirements for consumption. Our findings indicate that the intake of raw or poorly cooked contaminated bivalve mollusks could be a potential source of C. difficile, leading to a risk for human health.

Update on Commonly Used Molecular Typing Methods for Clostridioides difficile

“…Although the possibility of C. difficile being a foodborne disease has already been studied without reaching a clear conclusion [ 129 , 134 , 135 ], new evidence suggests that C. difficile is present in the environment and along the food chain [ 136 ]. C. difficile contamination in slaughterhouses has been described [ 137 , 138 ] as well as in other products, like shellfish [ 139 , 140 ]. Furthermore, molecular relationship between strains isolated from animal feces and the strains found as contamination in the processing plant has been found [ 141 ].…”

A Comprehensive Review for the Surveillance of Human Pathogenic Microorganisms in Shellfish

“…Alongside Enterococcus , Clostridium bacteria have been identified in shellfish ( Figure 1 ). While C. butyricum is generally considered to be non-pathogenic [ 46 ], C. perfrigens [ 47 , 48 ] and C. difficile [ 49 , 50 , 51 , 52 ] pose a significant risk of causing severe gastrointestinal infections. The anaerobic or microaerobic growth requirements of certain pathogens render their isolation for risk assessment challenging.…”

Molluscs—A ticking microbial bomb

“…in shellfish, C. difficile , raises concern because spores can survive the cooking temperatures given that shellfish is often consumed poorly cooked or raw. For example, C. difficile has been isolated from edible bivalve molluscs in Spain and Italy ( Agnoletti et al, 2019 ; Candel-Pérez et al, 2020 ). C. difficile collected from 702 molluscs harvested in the North Adriatic Sea ( Agnoletti et al, 2019 ) were detected in 16.9% of all bivalves specimens.…”

“…C. difficile strains showed a wide variety in PCR-ribotypes, most already detected in other animals or known as highly virulent and epidemic in humans. In Spain, Candel-Pérez et al (2020) analyzed 129 mollusc samples from different fishmongers and grocery stores in Murcia. C. difficile was isolated from 8.53% (11 specimens per total 129) of the investigated molluscs.…”