Dissemination of Multidrug-Resistant and with Class 1, Class 2, and Atypical Class 1 Integrons in China.

Emergence of multidrug-resistant , a major causative agent of bacterial dysentery, has generated many concerns not only in China but also worldwide. However, the prevalence of resistance caused by integron in the nonpopular season of diarrhea is not clear. Thirty-one and 22 samples collected in December 2010 from 10 cities of China were characterized for antimicrobial susceptibility, gene cassettes, widespread of integrons, and pulsed-field gel electrophoresis (PFGE) profile. Multidrug resistance (MDR) was detected in 29 (93.5%) and 20 (90.9%) isolates. Class 1 integrons were detected in 25 (80.6%) and in 13 (59.1%) isolates; class 2 integrons were detected in 26 (83.9%) and in 19 (86.4%) isolates. Interestingly, the atypical class 1 integrons were mostly detected in (45.2%) isolates, whereas in only 1 (4.5%) isolate. DNA sequencing revealed two novel cassette arrays, and , of class 1 integrons in , and in isolates. The cassette arrays, of class 2 integron and - of atypical class 1 integron, were also identified. PFGE profiles demonstrated A6 subtype of strains prevalent in Shanghai, Changchun, Jinan, and Changsha; and F6 subtype of prevalent in Jinan, Changchun, and Shanghai. The dissemination of MDR strains with integrons makes it an increasing public health problem in China. Increased surveillance and the development of adequate prevention strategies are warranted.