Nationwide surveillance of ribotypes and antimicrobial susceptibilities of toxigenic Clostridium difficile isolates with an emphasis on reduced doxycycline and tigecycline susceptibilities among ribotype 078 lineage isolates in Taiwan

OBJECTIVES: The information of antimicrobial susceptibility, toxin gene, and ribotype distribution of toxigenic Clostridium difficile isolates in Taiwan remain limited. PATIENTS AND METHODS: The study was conducted from January 2015 to December 2016 in 5 hospitals in Taiwan. Adults aged ≥20 years with a hospital stay for >5 days were included, and those with colectomy or intestinal infection due to other enteropathogens were excluded. Multiplex PCR was used to detect tcdA, tcdB, cdtA, cdtB, and tcdC deletions, and antimicrobial susceptibility for metronidazole, vancomycin, doxycycline, and tigecycline was investigated. Ribotypes of those isolates with tcdC deletion and tcdA+/tcdB+ were determined. RESULTS: Of 1112 C. difficile isolates collected from adults at 5 hospitals, 842 were toxigenic, including 749 (89.0%) tcdA+/tcdB+ isolates and 93 (11.0%) tcdA−/tcdB+. Of the toxigenic isolates, 76 (9.0%) had a tcdC deletion and were cdtA+/cdtB+, indicative of hypervirulence, and RT078 lineage, including RT126, RT127, and RT078, predominated (n=53, 76.3%). Similar to the susceptibility data in Asia countries, metronidazole or vancomycin resistance was rare, noted in 1.2% or 2.1%, respectively. Reduced doxycycline susceptibility (minimum inhibitory concentration [MIC] of ≥8 mg/L) was more common among RT078 lineage than non-RT078 lineage (75.9%, 44/58 vs 6.0%, 47/784; P<0.001). Also reduced tigecycline susceptibility (MIC ≥0.125 mg/L) was more common among RT078 lineage (20.7%, 12/58 vs 6.5%, 51/784; P<0.001). CONCLUSION: In Taiwan, toxigenic C. difficile isolates remain susceptible to metronidazole and vancomycin. RT078 lineage predominated among toxigenic isolates with cdtA, cdtB, and tcdC deletion, and more often had reduced doxycycline and tigecycline susceptibility than the isolates other than RT078 lineage.