Molecular epidemiology and antimicrobial susceptibility of Clostridium difficile isolated from hospitals during a 4-year period in China.

OBJECTIVE: The aim of this study was to perform molecular characterization for and determine the antimicrobial susceptibility profiles of Clostridium difficile collected from hospitals during a 4-year period (2009-2013) in China. METHODS: Strains of toxigenic C. difficile were isolated from patients with diarrhoea, and this was followed by typing using multilocus sequence typing (MLST) and testing for susceptibility to 10 antimicrobials by using the E-test. The mechanisms of resistance to moxifloxacin, erythromycin, clindamycin and tetracycline were investigated by PCR. RESULTS: A total of 405 non-duplicate toxigenic C. difficile isolates were identified, while 31 sequence types (STs) were identified. A predominant type, ST-54, accounted for 20.2 % of the STs, followed by ST-35 (16.3 %) and ST-37 (13.6 %). We found that 6.2 % of the isolates were binary toxin genes-positive, and 83.7 % of these belonged to ST-5. All of the isolates demonstrated 100 % susceptibility to first-line Clostridium difficile infection (CDI) therapies (i.e. metronidazole and vancomycin), while the resistance rates varied for the other antibiotics tested. Two hundred and ninety three (72.3 %) isolates were susceptible to moxifloxacin. All 112 moxifloxacin-resistant isolates had mutations resulting in an amino acid substitution in gryA and/or gyrB. The ermB gene was detected in 86.7 % (241/278) of the erythromycin- and clindamycin-resistant isolates, while the tetM gene was present in 97.1 % (85/87) of the tetracycline-resistant isolates. CONCLUSION: MLST typing revealed a wide variety of STs causing CDI, while ST-54 was the most common ST. All of the isolates were susceptible to metronidazole and vancomycin, while the resistance rates varied for the other antibiotics tested. There were no changes in the trends for the STs and antibiotic susceptibility profiles over 4 years.

Clostridium difficile carriage in healthy pregnant women in China.

Infection with Clostridium difficile has been shown to have particularly poor outcomes for pregnant women, including an increased risk of death. The purpose of this study was to investigate the prevalence, genotypic distribution, and characterization of C. difficile strains isolated from pregnant women without diarrhea in China. As part of this study, 3.7% (37 out of 1009) of samples acquired from pregnant females tested positive for C. difficile. Of these positive samples, 27.0% (10) were toxigenic isolates containing both toxin A and toxin B genes (A+B+), 13.5% (5) of the variant strains contained the toxin B gene (A-B+) only, while the rest were non-toxigenic isolates (59.5%, 22 isolates). Among the non-pregnant women without diarrhea tested, 1.4% (9 of 651) contained toxigenic isolates (all of which were A+B+). Sixteen different sequence types (STs) were isolated during the course of this study. ST-37 (ribotype 017) and ST-54 (ribotype 012) were the most frequent toxigenic types observed in pregnant women. All strains showed susceptibility to the antibiotics metronidazole and vancomycin. The resistance rates of toxigenic C. difficile strains isolated from pregnant females to clindamycin, erythromycin, moxifloxacin, levofloxacin, and rifampicin were 20%, 46.7%, 13.6%, 46.7% and 13.3%, respectively. There was no significant difference between resistance rates of toxigenic and non-toxigenic strains with respect to their susceptibility to these antibiotics. However, when compared with the same data from non-pregnant women, toxigenic strains from pregnant women showed lower resistance rates to clindamycin (P < 0.05).