High Prevalence of Antibiotic Resistance and Molecular Characterization of Integrons among Shigella Isolates in Eastern China

Abstract

A total of 747 Shigella isolates were collected from hospitals in Jiangsu Province of China. Susceptibilities to antimicrobials and integrons were tested. A total of 78.3% of S. flexneri isolates and a total of 74.3% S. sonei isolates were resistant to at least three antibiotics. Of the Shigella isolates, 74.7% had integron I and 82.6% had integron II. The conjunction of the high prevalence of integrons in Shigella and high resistance to antimicrobials will lead to rapid dissemination of resistant genes in this region. Bacterial diarrhea caused by Shigella remains a considerable public health problem in the world, especially in developing countries, where the disease may cause as many as 167 million episodes of diarrhea and over a million deaths annually (1). The surveillance of shigellosis studies from multicenters showed that shigellosis was more ubiquitous than previously thought (2). In China, it was estimated that over 800 million diarrhea episodes occurred annually (3), and Shigella is one of the principal etiologic organisms for diarrhea (4). Shigella species are classified by four serogroups, including S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. Of them, S. flexneri is the predominant species in most of developing countries (2, 5). Antibiotic therapy can limit the duration of shigellosis and shedding of the organism. However, resistance to the most often administered antibiotics has been increasing (5-7). The evidence from Hebei Province of China, Kuwait, and the United States showed that China has a far higher prevalence of resistance for all the bacteria studied (8).Integrons play an important role in the dissemination and recombination of antimicrobial drug resistance genes (9). They are common in Salmonella enterica and make an important contribution to the extent of antimicrobial resistance in this species (10,11). Recent studies also showed that integrons contributed to the spread of antimicrobial drug resistance genes among shigellosis cases (12). However, there are few data available to describe the prevalence of integrons of Shigella spp. circulating in China.In this study, we collected a total of 747 clinical Shigella isolates from the hospitals located in Jiangsu Province of China between January 2008 and November 2010. Stool specimens from patients with either diarrhea or dysentery were collected before the patients received antibiotics therapy and were then screened for Shigella spp. by conventional biochemical methods in local hospitals. The ages of patients ranged from 1 to 88 years. We defined diarrhea as the passage of Ն3 watery stools in a 24-h period. All isolates were identified using Rapid ID32E strips (bioMérieux Corp., Singapore) on an automatic biochemistry analyzer (Hitachi 917; Boehringer Mannheim, Japan) again. O and H antigens were characterized by slide agglutination with hyperimmune sera (Ningbo Tianrong Bio-pharmaceutical Company Limited), and the serotype was assigned to the Kauffmann-White scheme. Of these Shigella isolates, 716 were identified as Shigella; 491...

Antibiotic resistance and molecular characterization of shigella isolates recovered from children aged less than 5 years in Manhiça, Southern Mozambique

“…Thus, additional studies are needed in order to go further in this determination. In contrast to other studies [17,32] Serotype 6 in contrast, showed more heterogeneity, with scattered isolates in different PFGE patterns. Similarly, isolates with the same antibiotic resistance profile were found in different PFGE and vice-versa; however, MDR isolates were more frequently found in clusters suggesting a possible clonal spreading.…”

A 10-year surveillance of antimicrobial susceptibility patterns in Shigella sonnei isolates circulating in Jiangsu Province, China

“…In the USA during 2000-2010 [28], resistance rates to the common drugs nalidixic acid (1%), tetracycline (18%) and SXT (33%) were dramatically lower than those observed in the current study, whilst ampicillin had a similar resistance rate of 74%. In addition, in Eastern China high levels of resistance to ampicillin (70.8%), nalidixic acid (69.3%), tetracycline (74.8%) and SXT (73.8%) were reported [9]. The widespread nature of nalidixic acid and fluoroquinolone resistance has been documented in many countries [29,30].…”

“…Bacterial molecular typing is frequently applied for outbreak surveillance and phylogenetic investigation. Strain-specific fingerprints generated are used to facilitate the identification of disease transmission routes and sources [7][8][9][10][11]. To date, various genotyping methods including biotyping, multilocus variable-number tandem-repeat analysis (MLVA) and PFGE have been used for the epidemiological investigation of S. sonnei [31,32].…”

“…Antimicrobial treatment is usually recommended for shigellosis as it can reduce the duration of symptoms and the severity of illness by shortening the period of pathogen excretion [8]. However, owing to long-term overuse of antimicrobials, drugresistant and multidrug-resistant (MDR) Shigella isolates prevail worldwide [9,10]. Evidence from China [11], Bangladesh [5], Belgium [12], Gabon [13] and the USA [14] indicated that China has a much higher prevalence of resistance to most commonly used antimicrobials.…”

Molecular characterization of the extended-spectrum beta-lactamase (ESBL)-producing Shigella spp. in Shanghai

“…The production of ESBLs is the major defense mechanism against third-generation cephalosporins employed by Enterobacteriaceae, including Shigella species. Recent reports from Jiangsu and Anhui Provinces located in eastern China, which neighbor Shanghai, showed that the rates of resistance to CTX were 21.5 % and 26.4 %, respectively, among Shigella isolates [14,15]. Therefore, the high prevalence of ESBL-producing Shigella isolates in eastern China is a threat to public health, and tracking and monitoring of the rapid spread of ESBL producers is urgently required.…”