Abstract
Clostridium difficile, the causal agent of antibiotic-associated diarrhea, has a complex epidemiology poorly studied in Latin America. We performed a robust genomic and phenotypic profiling of 53 C. difficile clinical isolates established from diarrheal samples from either intrahospital (IH) or community (CO) populations in central Colombia. In vitro tests were conducted to evaluate the cytopathic effect, the minimum inhibitory concentration of ten antimicrobial agents, the sporulation efficiency and the colony forming ability. Eleven different sequence types (STs) were found, the majority present individually in each sample, however in three samples two different STs were isolated. Interestingly, CO patients were infected with STs associated with hypervirulent strains (ST-1 in Clade-2). Three coexistence events (two STs simultaneously detected in the same sample) were observed always involving ST-8 from Clade-1. A total of 2,502 genes were present in 99% of the isolates with 95% of identity or more, it represents a core genome of 28.6% of the 8,735 total genes identified in the set of genomes. A high cytopathic effect was observed for the isolates positive for the two main toxins but negative for binary toxin (TcdA+/TcdB+/CDT− toxin production type), found only in Clade-1. Molecular markers conferring resistance to fluoroquinolones (cdeA and gyrA) and to sulfonamides (folP) were the most frequent in the analyzed genomes. In addition, 15 other markers were found mostly in Clade-2 isolates. These results highlight the regional differences that C. difficile isolates display, being in this case the CO isolates the ones having a greater number of accessory genes and virulence-associated factors.
Highlights
Clostridium difficile (CD) is an anaerobic Gram-positive spore-forming bacillus recognized as the causal agent of antibiotic-associated diarrhea and a wide range of gastrointestinal syndromes, including pseudomembranous colitis and toxic megacolon, that in complex cases can result in death[1]
The binary toxin, which has ADP-ribosyl transferase activity, may have a role in the adherence of C. difficile by acting in a synergistic way with other factors such as surface proteins[6]. Another factor involved in the complexity of C. difficile infection (CDI) management is antibiotic resistance, which has been associated with polymorphisms and/or the presence of genes that can be transported by mobile genetic elements[7]
Fifty-three clinical isolates were established from 17 fecal samples from patients suffering diarrhea in whom CDI was detected as part of a previous screening[9]
Summary
Clostridium difficile (CD) is an anaerobic Gram-positive spore-forming bacillus recognized as the causal agent of antibiotic-associated diarrhea and a wide range of gastrointestinal syndromes, including pseudomembranous colitis and toxic megacolon, that in complex cases can result in death[1]. The binary toxin (composed of subunits CdtA and CdtB), which has ADP-ribosyl transferase activity, may have a role in the adherence of C. difficile by acting in a synergistic way with other factors such as surface proteins[6]. Another factor involved in the complexity of CDI management is antibiotic resistance, which has been associated with polymorphisms and/or the presence of genes that can be transported by mobile genetic elements[7]. A detailed high-resolution genomic and phenotypic profiling of C. difficile samples collected in Bogotá (central Colombia) was carried out here, to obtain a broad insight about differences in CDI in community and intrahospital populations in Bogotá, Colombia
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