Global prevalence of Clostridioides difficile in 17,148 food samples from 2009 to 2019: a systematic review and meta-analysis

BACKGROUND

Clostridioides (Clostridium) difficile is an important infectious pathogen, which causes mild-to-severe gastrointestinal infections by creating resistant spores and producing toxins. Spores contaminated foods might be one of the most significant transmission ways of C. difficile-associated infections. This systematic review and meta-analysis study were conducted to investigate the prevalence of C. difficile in food.

METHODS

Articles that published the prevalence of C. difficile in food in PubMed, Web of Science, and Scopus databases were retrieved using selected keywords between January 2009 and December 2019. Finally, 17,148 food samples from 60 studies from 20 countries were evaluated.

RESULTS

The overall prevalence of C. difficile in various foods was 6.3%. The highest and lowest levels of C. difficile contamination were detected to seafood (10.3%) and side dishes (0.8%), respectively. The prevalence of C. difficile was 4% in cooked food, 6.2% in cooked chicken and 10% in cooked seafood.

CONCLUSIONS

There is still little known concerning the food-borne impact of C. difficile, but the reported contamination might pose a public health risk. Therefore, to improve the food safety and prevent contamination with C. difficile spores, it is necessary to observe hygienic issues during foods preparation, cooking and transfer.

Clostridioides difficile in Non-hospital Sources (Animals, Food, and Environment) in Asian Countries: A Literature Review

Context: Clostridioides difficile (C. difficile) is an agent responsible for severe infection with a high mortality rate in healthcare facilities. With the discovery of C. difficile in the community, it was assumed that this bacterium might be transmitted to humans through non-hospital sources. Evidence Acquisition: This study examined different aspects of the epidemiology of C. difficile in Asian countries with a review of the literature using search engines such as Web of Science, Scopus, and PubMed. Results: Based on the literature pertaining to Asia, the highest rate of C. difficile is found in samples collected from farm animals, red meat, and meat-based products. Two ribotypes 027 and 078, as hypervirulent factors, were found in different non-hospital sources. Resistance to the most frequently used antibiotics in healthcare setting was observed in C. difficile. Conclusions: Due to the heterogeneity of the examination of C. difficile, understanding the actual condition of C. difficile is difficult. However, the presence of two hypervirulent ribotypes of C. difficile in non-hospital sources is alarming. It seems that it is necessary to perform further studies on C. difficile in non-hospital sources. Defining a focal point for such research could be helpful to explore the situation of C. difficile in clinical settings and communities of Asian countries.

Global and Historical Distribution of Clostridioides difficile in the Human Diet (1981-2019): Systematic Review and Meta-Analysis of 21886 Samples Reveal Sources of Heterogeneity, High-Risk Foods, and Unexpected Higher Prevalence Toward the Tropic

Clostridioides difficile (CD) is a spore-forming bacterium that causes life-threatening intestinal infections in humans. Although formerly regarded as exclusively nosocomial, there is increasing genomic evidence that person-to-person transmission accounts for only <25% of cases, supporting the culture-based hypothesis that foods may be routine sources of CD-spore ingestion in humans. To synthesize the evidence on the risk of CD exposure via foods, we conducted a systematic review and meta-analysis of studies reporting the culture prevalence of CD in foods between January 1981 and November 2019. Meta-analyses, risk-ratio estimates, and meta-regression were used to estimate weighed-prevalence across studies and food types to identify laboratory and geographical sources of heterogeneity. In total, 21886 food samples were tested for CD between 1981 and 2019 (96.4%, n = 21084, 2007–2019; 232 food-sample-sets; 79 studies; 25 countries). Culture methodology, sample size and type, region, and latitude were sources of heterogeneity (p < 0.05). Although non-strictly-anaerobic methods were reported in some studies, and we confirmed experimentally that improper anaerobiosis of media/sample-handling affects CD recovery in agar (Fisher, p < 0.01), most studies (>72%) employed the same (one-of-six) culture strategy. Because the prevalence was also meta-analytically similar across six culture strategies reported, all studies were integrated using three meta-analytical methods. At the study level (n = 79), the four-decade global cumulative-prevalence of CD in the human diet was 4.1% (95%CI = −3.71, 11.91). At the food-set level (n = 232, mean 12.9 g/sample, similar across regions p > 0.2; 95%CI = 9.7–16.2), the weighted prevalence ranged between 4.5% (95%CI = 3–6%; all studies) and 8% (95%CI = 7–8%; only CD-positive-studies). Risk-ratio ranking and meta-regression showed that milk was the least likely source of CD, while seafood, leafy green vegetables, pork, and poultry carried higher risks (p < 0.05). Across regions, the risk of CD in foods for foodborne exposure reproducibly decreased with Earth latitude (p < 0.001). In conclusion, CD in the human diet is a global non-random-source of foodborne exposure that occurs independently of laboratory culture methods, across regions, and at a variable level depending on food type and latitude. The latitudinal trend (high CD-food-prevalence toward tropic) is unexpectedly inverse to the epidemiological observations of CD-infections in humans (frequent in temperate regions). Findings suggest the plausible hypothesis that ecologically-richer microbiomes in the tropic might protect against intestinal CD colonization/infections despite CD ingestion.

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

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.