Epidemiology and Drug Resistance of Shigellosis, Taiwan, 2015

Epidemiology and Drug Resistance of Shigellosis, Taiwan, 2015

A total of 186 shigellosis cases were reported in 2015 and 56.5% of which were imported. Of the 147 isolates collected in the year by the Central Regional Laboratory of Taiwan Centers for Disease Control, 86 isolates (58.5%) were Shigella sonnei, 57 (38.8%) were S. flexneri and 4 (2.7%) were S. boydii, respectively. Among the 86 S. sonnei isolates, 25 (29.1%) were recovered from immigrant workers from Indonesia and Vietnam, and 61 (70.1%) were Taiwanese of whom 14 acquired the infections during traveling abroad. Of the 57 S. flexneri isolates, 39 (68.4%) were recovered from Indonesian immigrant workers and 18 were Taiwanese of whom 4 had travel history abroad. The 4 S. boydii isolates were recovered from Indonesian workers and with travel history to Indonesia. Antimicrobial susceptibility testing revealed that 47 of 78 S. sonnei isolates tested were ciprofloxacin-resistant. All the ciprofloxacin-resistant isolates were recovered from Taiwanese among whom 11 had travel history to China, Japan, Vietnam, Indonesia and Cambodia, and 31 were HIV-infected. All the cases with HIV infection were male of 20–46 (average 31.4) year-old and 2 cases had traveled to China and Japan during the incubation period. The first S. flexneri 3a infected case emerged in June. Nine S. flexneri 3a infected cases were found in 2015; they were Taiwanese, male, 22-44 years-old (average 33.3), and 6 were HIV-infected. All S. flexneri 3a isolates belonged to a common PFGE genotype and all but one were resistant to azithromycin. Ciprofloxacin and azithromycin are the recommended treatment drugs for shigellosis in Taiwan. In the past, Shigella strains resistant to these two drugs were infrequently detected but, in 2015, Shigella strains with ciprofloxacin resistance had become prevalent and azithromycin resistance had emerged. The resistant strains were primarily circulated among the men who have sex with men (MSM). We suggest that public health authorities have to routinely perform antimicrobial susceptibility testing on Shigella isolates for the treatment of Shigella infections and strengthen hygiene education among MSM to halter the spread of ciprofloxacin- and azithromycin-resistant strains.