Abstract
Clostridium difficile is an important cause of infectious colitis among hospitalized patients across the globe. The pathogenic potential of C. difficile in producing significant morbidity and mortality is mainly due to production of toxins A and B. The outbreaks of C. difficile infection (CDI) are due to changes in the genetic sequences of the organism. There is hardly any molecular study reported on the prevalent types of C. difficile strains in India. Toxinotyping and sequencing of locally circulating C. difficile isolates from patients presenting to our tertiary care center of North India were done. C. difficile strains (n = 174) isolated from 1,110 fecal samples from patients with suspected CDI were subjected to toxinotyping and partial sequencing of tcdA and tcdB genes. Comparison of nucleotide sequences with reference C. difficile 630 strain using BLAST was made and translated into corresponding amino acid sequences by ExPASy. Of 174 C. difficile isolates, 121 were toxigenic, belonging to toxinotype 0 (n = 76) and VIII (n = 45). Partial sequencing of toxin genes using bioinformatics approaches revealed changes in toxin A sequences of five (50%) C. difficile isolates, but the translated nucleotide sequences showed substitution in only three of them. No variation was seen in the toxin B nucleotide sequences. Interstrain variations were found in the clinical C. difficile isolates in our region. PCR amplified toxigenic genes followed by sequencing can help to identify genetic changes and pathogenicity of varied collection of C. difficile isolates.
Highlights
Clostridium difficile, an anaerobic spore-bearing organism, is an important cause of infectious colitis among in-patients across the globe and so in North America and Europe [1]
All of the toxigenic isolates were checked for the presence of fragments of toxins A1–A3 and B1–B3
Of the 121 toxigenic isolates, 76 (62.8%) belonged to toxinotype 0 and 45 (37.2%) to toxinotype VIII
Summary
Clostridium difficile, an anaerobic spore-bearing organism, is an important cause of infectious colitis among in-patients across the globe and so in North America and Europe [1]. From 2003 onward, several outbreaks have been reported due to NAP1/BI/027, a high-level toxin-producing C. difficile strain isolated from North America [3], Europe [4], and Japan [5]. Comparison of whole genome sequencing of historical strain with the hypervirulent strain showed that C. difficile had acquired genes that enabled it to survive better in the environment [7]. This hypervirulent strain is linked with a more serious course of infection, higher relapse rate, and complications leading to higher mortality [8]. Toxinotyping and sequencing of locally circulating C. difficile isolates from patients presenting to our tertiary care center of North India were done
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