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. 2021 Spring;14(2):165-173.

Frequency of toxin genes and antibiotic resistance pattern of Clostridioides difficile isolates in diarrheal samples among hospitalized patients in Hamadan, Iran

Leili Shokoohizadeh  1 , Fatemeh Alvandi  1 , Abbas Yadegar  2 , Masoumeh Azimirad  2 , Seyed Hamid Hashemi  1   3 , Mohammad Yousef Alikhani  1
Affiliations

Frequency of toxin genes and antibiotic resistance pattern of Clostridioides difficile isolates in diarrheal samples among hospitalized patients in Hamadan, Iran

Leili Shokoohizadeh et al. Gastroenterol Hepatol Bed Bench. 2021 Spring.

Abstract

Aim: This study was designed to investigate the prevalence of Clostridioides difficile, its toxin-producing genes, and antibiotic resistance patterns in diarrheal samples from hospitalized patients in Hamadan, Iran.

Background: Today, concerns over Clostridioides difficile infection (CDI) have significantly increased due to reduced susceptibility to antibiotics used for CDI treatment. Toxins produced by C. difficile strains are associated with disease severity and outcome.

Methods: In this cross-sectional study, a total of 130 diarrheal samples of patients admitted to different wards of three hospitals in Hamadan from November 2018 to September 2019 were collected. C. difficile isolates were identified by culture on CCFA and PCR (Polymerase chain reaction). The presence of toxin-encoding genes (tcdA and tcdB) and binary toxin genes (cdtA and cdtB) was analyzed by PCR. Resistance of the isolates to metronidazole, vancomycin and clindamycin antibiotics was determined using agar dilution method.

Results: Out of 130 diarrheal samples from hospitalized patients, 16 (12.3%) C. difficile isolates were obtained. PCR results were positive for two toxin-producing genes, tcdA and tcdB, in all (100%) C. difficile isolates, and the binary toxin genes cdtA and cdtB were detected in 6 (37.5%) and 8 (50%) isolates, respectively. The results of antibiotic susceptibility testing showed resistance to metronidazole, vancomycin, and clindamycin in 3 (18.7%), 3 (18.7%), and 2 (12.5%) isolates, respectively, and all isolates were resistant to rifampicin.

Conclusion: The results of this study showed toxigenic C. difficile with tcdA + /tcdB + profile is a major cause of nosocomial diarrhea in Hamadan, and clinical laboratories should routinely perform C. difficile diagnostic testing on diarrheal specimens of hospitalized patients. Resistance to conventional antibiotic therapy against C. difficile should be considered as a warning to prevent irrational administration of antibiotics.

Keywords: Antibiotic resistance; Binary toxin; Clostridioides difficile; TcdA; TcdB.

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Figures

Figure 1
Figure 1
Gel electrophoresis of PCR products for C. difficile identification and toxin encoding genes in isolates from hospitalized patients in Hamadan. (a) cdd3; (b) tcdA; (c) tcdB; (d) cdtA and cdtB genes. Lane M, 100 bp DNA size marker
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