Epidemic ribotypes of Clostridium (now Clostridioides) difficile are likely to be more virulent than non-epidemic ribotypes in animal models

Abstract

Background: Clostridioides difficile infections have become more frequently diagnosed and associated with greater disease severity, which has resulted in an increase burden on the healthcare system. These increases are attributed to the increased prevalence of hypervirulent strains encompassing select ribotypes. These epidemic ribotypes were characterized as hypervirulent due to higher in vitro spore and toxin production, as well as increased incidence, severity and mortality within patients. However, it is unclear whether epidemic ribotypes are truly more virulent than non-epidemic ribotypes in vivo. Furthermore, there is conflicting evidence about the ability of a strain's in vitro phenotype to be predictive of their in vivo virulence. The goals of the current studies were to determine if epidemic ribotypes are more virulent than other ribotypes in animal models, and whether the in vitro virulence phenotype of an isolate or ribotype predict in vivo virulence. Results: To determine if epidemic strains were truly more virulent than other non-epidemic strains, the in vivo virulence of 13 C. difficile isolates (7 non-epidemic and 6 epidemic ribotype isolates) were determined in murine and hamster models of CDI. The isolates of epidemic ribotype of C. difficile were found to be more virulent in both the murine and hamster models than non-epidemic isolates. In particular, the group of epidemic ribotypes of C. difficile had lower LD 50 values in hamsters. The increased severity of disease was associated with higher levels of Toxin A and Toxin B production found in fecal samples, but not numbers of organisms recovered. The isolates were further characterized for their in vitro virulence phenotypes, e.g. toxin production, growth rates, spore formation and adherence of spores to intestinal epithelial cell lines. Although there were higher levels of toxins produced and greater adherence for the group of epidemic ribotypes, the in vitro profiles of individual isolates were not always predictive of their in vivo virulence. Conclusions: Overall, the group of epidemic ribotypes of C. difficile were more virulent in vivo despite individual isolates having similar phenotypes to the non-epidemic isolates in vitro.

Characterization of the virulence of three novel clade 2 Clostridioides (Clostridium) difficile strains and a two-year screening in animals and humans in Brazil

“…Previous reports have shown that isolates of epidemic RTs were found to be more virulent in hamster models than non-epidemic isolates, but the in vitro profiles of individual isolates were not always predictive of their in vivo virulence, similar to our findings [75,76]. According to Vitucci et al [76], toxin levels may represent one of the relevant factors involved in disease severity. In fact, C. difficile strains with higher colonization capability can cause severe infection even with low toxin production [19]; these findings can partially explain the results observed in the present study.…”

“…Few studies have examined the in vivo virulence of different RTs using animal models, but hamsters have been successfully used in these survival studies because of their high sensitivity to CDI [26,[73][74][75]. Previous reports have shown that isolates of epidemic RTs were found to be more virulent in hamster models than non-epidemic isolates, but the in vitro profiles of individual isolates were not always predictive of their in vivo virulence, similar to our findings [75,76]. According to Vitucci et al [76], toxin levels may represent one of the relevant factors involved in disease severity.…”

Clostridium Difficile and COVID-19: General Data, Ribotype, Clinical Form, Treatment-Our Experience from the Largest Infectious Diseases Hospital in Western Romania

“…Before the beginning of the COVID-19 pandemic, the incidence of CDI was rising in some European countries and in the United States of America [15]. Moreover, in recent years, there have been outbreaks of particularly severe CDI associated with increased mortality, largely attributed to the spread of a specific type of Clostridium difficile, known in Europe as ribotype 027 [16][17][18][19]. With the identification of the epidemic 027 ribotype, there has been an ongoing debate regarding whether this genetic cluster of C. difficile is more virulent than non-epidemic ribotypes, but despite this, it is important to maintain focus on CDI in general rather than the type [20].…”

Foodborne Clostridioides Species: Pathogenicity, Virulence and Biocontrol Options

“…The ability of C. difficile to adhere to intestinal epithelium is considered a factor in the pathogenicity of clinical disease. The exosporium is believed to aid in the adherence of C. difficile spores to the epithelium and its composition varies amongst strains, suggesting why subvariants have different pathogenicity [56]. C. difficile spores can survive temperatures of 71 • C for 2 h, and 85 • C for 10 min, indicating the failure of current pasteurisation or thermal preservation techniques to eliminate C. difficile spores from food items [51].…”