Molecular Epidemiology and Risk Factors of Clostridium difficile ST81 Infection in a Teaching Hospital in Eastern China

Abstract

Background: The prevalence of Clostridium difficile causes an increased morbidity and mortality of inpatients, especially in Europe and North America, while data on C. difficile infection (CDI) are limited in China.

Methods: From September 2014 to August 2019, 562 C. difficile isolates were collected from patients and screened for toxin genes. Multilocus sequence typing (MLST) and antimicrobial susceptibility tests by E-test and agar dilution method were performed. A case group composed of patients infected with sequence type (ST) 81 C. difficile was compared to the non-ST81 infection group and non CDI diarrhea patients for risk factor and outcome analyses.

Results: The incidence of inpatients with CDI was 7.06 cases per 10,000 patient-days. Of the 562 C. difficile isolates, ST81(22.78%) was the predominant clone over this period, followed by ST54 (11.21%), ST3 (9.61%), and ST2 (8.72%). Toxin genotype tcdA+tcdB+cdt- accounted for 50.18% of all strains, while 29.54% were tcdA-tcdB+cdt- genotypes. Overall, no isolate was resistant to vancomycin, teicoplanin or daptomycin, and resistance rates to meropenem gradually decreased during these years. Although several metronidazole-resistant strains were isolated in this study, the MIC values decreased during this period. Resistance rates to moxifloxacin and clindamycin remained higher than those to the other antibiotics. Among CDI inpatients, longer hospitalization, usage of prednisolone, suffering from chronic kidney disease or connective tissue diseases and admission to emergency ward 2 or emergency ICU were significant risk factors for ST81 clone infection. All-cause mortality of these CDI patients was 4.92%(n=18), while the recurrent cases accounted for 5.74%(n=21). The 60-day mortality of ST81-CDI was significantly higher than non-ST81 infected group, while ST81 also accounted for most of the recurrent CDI cases.

Conclusion: This study revealed the molecular epidemiology and risk factors for the dominant C. difficile ST81 genotype infection in eastern China. Continuous and stringent surveillance on the emerging ST81 genotype needs to be initiated.

Keywords: Clostridium difficile infection; epidemiology; multilocus sequence typing; resistance; risk factors.

Figure 1

Distribution of the 562 strains according to admission departments. OP, Outpatients; GD, Gastroenterology department; ED, Emergency department; CD, cadre (geriatric) department; ND, Nephrology department; HD, Hematology department; ICU, Intensive care unit.

Figure 2

Dynamic changes in proportion of the most frequent sequence types over the three time periods.

Figure 3

Phylogenetic analysis of C. difficile. ST numbers assigned are overprinted, while the node size is proportional to the quantity of isolates presenting in this database. Numbers of the links represent the amount of locus variants between the two STs. Clade 4 is clustered in a blue semitransparent circle. Clade 2, Clade 3, and Clade 5, each containing one ST genotype, are highlighted by red rectangular frames. The rest of ST genotypes all belong to Clade 1.

Figure 4

Proportion of toxin genotypes of the 562 strains.

Figure 5

MIC distribution (A, D) and dynamic changes of resistance rate (B, C, E, F) to clindamycin, moxifloxacin, meropenem, and rifaximin of 562 C. difficile isolates.

Figure 6

Multivariate logistic regression analysis for independent risk factors of ST81 CDI when non-ST81 CDI (A) or non-CDI diarrhea patients (B) were used as control.

Figure 7

Kaplan-Meier survival curves of patients with ST81 clone infection compared with non-ST81 clone infection (p=0.001 by log-rank test).

Figure 8

Proportion of major sequence types isolated from recurrent CDI patients.