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Pathogenicity locus determinants and toxinotyping of Clostridioides difficile isolates recovered from Iranian patients.

ABSTRACT: Little is known about the toxin profiles, toxinotypes and variations of toxin Clostridioides difficile C (tcdC) in Iranian C. difficile isolates. A total of 818 stool specimens were obtained from outpatients (n = 45) and hospitalized patients (n = 773) in Tehran, Iran, from 2011 to 2017. The 44 C. difficile isolates were subjected to PCR of toxin C. difficile A (tcdA), toxin C. difficile B (tcdB), tcdA 3'-end deletion, toxinotyping and sequencing of the tcdC gene. Thirty-eight isolates (86.36%) were identified as tcdA and tcdB positive, and the remaining six isolates (13.63%) were nontoxigenic. All tcdA- and tcdB-positive isolates yielded an amplicon of 2535 bp by PCR for the tcdA 3' end. Fourteen (36.84%), seventeen (44.73%) and seven (18.43%) isolates belonged to wild-type, toxin C. difficile C subclone3 (tcdC-sc3) and tcdC-A genotype of tcdC, respectively. Thirty-one isolates (81.57%) belonged to toxinotype 0, and seven isolates (18.42%) were classified as toxinotype V. This study provides evidence for the circulation of historical and hypervirulent isolates in the healthcare and community settings. Furthermore, it was also demonstrated that the tcdC-A genotype and toxinotype V are not uncommon among Iranian C. difficile isolates.

SUBMITTER: Aliramezani A

PROVIDER: S-EPMC6072886 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Pathogenicity locus determinants and toxinotyping of Clostridioides difficile isolates recovered from Iranian patients.

Aliramezani A A Talebi M M Baghani A A Hajabdolbaghi M M Salehi M M Abdollahi A A Afhami S S Marjani M M Golbabaei F F Boroumand M A MA Sarrafnejad A A Yaseri M M Ghourchian S S Douraghi M M

New microbes and new infections 20180802

Little is known about the toxin profiles, toxinotypes and variations of toxin Clostridioides difficile C (tcdC) in Iranian C. difficile isolates. A total of 818 stool specimens were obtained from outpatients (n = 45) and hospitalized patients (n = 773) in Tehran, Iran, from 2011 to 2017. The 44 C. difficile isolates were subjected to PCR of toxin C. difficile A (tcdA), toxin C. difficile B (tcdB), tcdA 3'-end deletion, ...[more]

PMID: 30094031

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Project description:Clostridium difficile infection (CDI) is an important cause of mortality and morbidity in healthcare settings. The major virulence determinants are large clostridial toxins, toxin A (tcdA) and toxin B (tcdB), encoded within the pathogenicity locus (PaLoc). Isolates vary in pathogenicity from hypervirulent PCR-ribotypes 027 and 078 with high mortality, to benign non-toxigenic strains carried asymptomatically. The relative pathogenicity of most toxigenic genotypes is still unclear, but may be influenced by PaLoc genetic variant. This is the largest study of C. difficile molecular epidemiology performed to date, in which a representative collection of recent isolates (n?=?1290) from patients with CDI in Oxfordshire, UK, was genotyped by multilocus sequence typing. The population structure was described using NeighborNet and ClonalFrame. Sequence variation within toxin B (tcdB) and its negative regulator (tcdC), was mapped onto the population structure. The 69 Sequence Types (ST) showed evidence for homologous recombination with an effect on genetic diversification four times lower than mutation. Five previously recognised genetic groups or clades persisted, designated 1 to 5, each having a strikingly congruent association with tcdB and tcdC variants. Hypervirulent ST-11 (078) was the only member of clade 5, which was divergent from the other four clades within the MLST loci. However, it was closely related to the other clades within the tcdB and tcdC loci. ST-11 (078) may represent a divergent formerly non-toxigenic strain that acquired the PaLoc (at least) by genetic recombination. This study focused on human clinical isolates collected from a single geographic location, to achieve a uniquely high density of sampling. It sets a baseline of MLST data for future comparative studies investigating genotype virulence potential (using clinical severity data for these isolates), possible reservoirs of human CDI, and the evolutionary origins of hypervirulent strains.

Project description:There has been a decrease in healthcare-associated Clostridioides difficile infection (CDI) in Australia, coupled with an increase in the genetic diversity of strains isolated in these settings, and an increase in community-associated cases. To explore this changing epidemiology, we studied the genetic relatedness of C. difficile isolated from patients at a major hospital in Melbourne, Australia. Whole-genome sequencing of C. difficile isolates from symptomatic (n = 61) and asymptomatic (n = 10) hospital patients was performed. Genomic comparisons were made using single-nucleotide polymorphism (SNP) analysis, ribotyping, and toxin, resistome, and mobilome profiling. C. difficle clade 1 strains were found to be predominant (64/71), with most strains (63/71) encoding both toxins A and B (A+B+). Despite these similarities, only two isolates were genetically related (≤2 SNPs) and a diverse range of ribotypes was detected, with those predominating including ribotypes commonly found in community-associated cases. Five non-toxigenic (A-B-CDT-) clade 1 strains were identified, all in asymptomatic patients. Three clade 4 (A-B+CDT-) and four clade 5 (A+B+CDT+) strains were detected also, with these strains more likely to carry antimicrobial resistance determinants, many of which were associated with mobile genetic elements. Overall, within a single hospital, C. difficile-associated disease was caused by a diverse range of strains, including many strain types associated with community and environmental sources. While strains carried asymptomatically were more likely to be non-toxigenic, toxigenic strains were isolated also from asymptomatic patients, which together suggest the presence of diverse sources of transmission, potentially including asymptomatic patients. IMPORTANCE There has been a decrease in healthcare-associated Clostridioides difficile infection in Australia, but an increase in the genetic diversity of infecting strains, and an increase in community-associated cases. Here, we studied the genetic relatedness of C. difficile isolated from patients at a major hospital in Melbourne, Australia. Diverse ribotypes were detected, including those associated with community and environmental sources. Some types of isolates were more likely to carry antimicrobial resistance determinants, and many of these were associated with mobile genetic elements. These results correlate with those of other recent investigations, supporting the observed increase in genetic diversity and prevalence of community-associated C. difficile, and consequently the importance of sources of transmission other than symptomatic patients. Thus, they reinforce the importance of surveillance for in both hospital and community settings, including asymptomatic carriage, food, animals, and other environmental sources to identify and circumvent important sources of C. difficile transmission.

Dataset Information

Pathogenicity locus determinants and toxinotyping of Clostridioides difficile isolates recovered from Iranian patients.

Publications

Pathogenicity locus determinants and toxinotyping of <i>Clostridioides difficile</i> isolates recovered from Iranian patients.

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