The Dissemination of Fusidic Acid Resistance Among Clinical Isolates in Wenzhou, China.

Purpose: Fusidic acid (FA), a potent steroidal antibiotic, is used topically to treat skin and soft tissue infections (SSTIs) caused by . The aim of this study is to report the prevalence of fusidic acid resistance among clinical isolates from a tertiary hospital in Wenzhou, east China.

Methods: The antibiotic susceptibility of isolates was determined by disc diffusion method and agar dilution method. Then, FA-resistant isolates were characterized by multi-locus sequence typing, SCC typing and pulsed-field gel electrophoresis.

Results: In the present study, the 55 (7.7%) FA-resistant among 711 clinical isolates were isolated from different parts of 53 patients. Fifty-five FA-resistant isolates with FA MIC values ranged from 4 to 32 μg/mL. Among them, 50 (90.9%) were identified as methicillin-resistant (MRSE), in which were positive. Meanwhile, the positive rates of and genes among FA-resistant isolates were 85.5% (47/55) and 7.3% (4/55), respectively. All 55 isolates mentioned above were susceptible to vancomycin. More than 50% of FA-resistant isolates were resistant to non-β-lactam antimicrobials including erythromycin (80.0%, 44/55), clindamycin (65.5%, 36/55), ciprofloxacin (63.6%, 35/55) and sulfamethoxazole (63.6%, 35/55). A total of 14 sequence types (STs) were identified among the 55 FA-resistant isolates, of which, ST2 (24/55, 43.6%) was the most predominant type. And the eBURST analysis showed that CC2, CC5 and CC247 accounted for 43.6% (24/55), 27.3% (15/55) and 14.5% (5/55), respectively. Meanwhile, a total of four SCC types (I, III, IV, V) were identified among the 55 FA-resistant . Furthermore, the pulsed field gel electrophoresis divided the 55 isolates into 20 types, namely A-T. Q-type strains were most prevalent, accounting for 30.9% (17/55).

Conclusion: Taken together, the dissemination of ST2 clone with FA resistance can cause trouble in controlling infections.