Abstract
Shigella represents one of the major diarrhea-inducing pathogens threatening public health, but its prevalence and antimicrobial resistance profile in Xinjiang Uygur Autonomous region, China, remains unclear. We conducted comprehensive investigation of Shigella serotype distribution and antimicrobial resistance pattern in Xinjiang, identifying 458 Shigella isolates between 2008 to 2014. Shigella flexneri was identified as predominant species, and several S. flexneri serotypes were isolated, including atypical serotypes 1c, 2c, and 4s. Dominant S. flexneri serotypes were 2a, 1b, 2b, and Xv, different from those generally dominant in China. A hybrid serotype pattern was observed, which included the major Chinese serotypes (2a, Xv) and those predominant in Pakistan (1b, 2b). Shigella sonnei was shown to have a lower frequency compared with that generally observed in China, but an increasing trend of infections associated with this pathogen was observed. Furthermore, a high frequency of drug resistance and different Shigella antimicrobial resistance patterns were demonstrated as well, including very severe resistance phenotypes, such as multidrug resistance and resistance to frontline antibiotics. Seventy-five cephalosporin-resistant Shigella isolates were frequently identified with the resistance determinants that can undergo horizontal transfer, such as blaOXA, blaTEM, blaCTX-M, and integrons, facilitating the development of cephalosporin resistance among Shigella subtypes. Additionally, genetic analyses demonstrated that all 86 quinolone-resistant S. flexneri isolates possess 3–4 mutation sites in quinolone resistance-determining regions, primarily contributing to their resistance to quinolone. However, S. sonnei isolates were not shown to be quinolone resistant. Co-resistance to cephalosporins and quinolones was detected in 17 S. flexneri isolates, and these isolates were additionally multidrug resistant and carried β-lactamase genes and quinolone-resistance determinants. As is demonstrated in this study, dominant serotypes of Shigella were distributed in unique trend with dangerous drug resistance patterns. Novel strategies are urgently required to prevent the development of drug resistance among diarrhea-inducing pathogens.
Highlights
Shigella spp. are recognized as important causative agents of diarrheal diseases in humans [1,2,3,4]
S. flexneri has primarily been the epidemic species, caused diarrhea in developing countries, while S. sonnei has been prevalent in the developed countries [11]
Several serologically atypical isolates of S. flexneri were identified in recent studies [16,17,18], and these Shigella subgroup and serotype variations may lead to difficulties in the prevention and treatment of Shigella infection
Summary
Shigella spp. are recognized as important causative agents of diarrheal diseases in humans [1,2,3,4]. S. sonnei prevalence has demonstrated an increasing trend in some Asian countries recently [12,13,14,15], together with the economic development. Several serologically atypical isolates of S. flexneri were identified in recent studies [16,17,18], and these Shigella subgroup and serotype variations may lead to difficulties in the prevention and treatment of Shigella infection. The emergence and dissemination of antimicrobial resistance (AMR) aggravate Shigella prevalence. The antibiotic-resistant Shigella isolates have been identified throughout China [1,7,16,26], aggravating the challenges associated with the treatment and prevention of shigellosis
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