Molecular Epidemiology of
            <i>Shigella</i>
            in aTaiwan Township during 1996 to2000

Chen, Jiann-Hwa; Chiou, Chien-Shun; Chen, Pei–Chun; Liao, Tung-Liang; Liao, Tsai‐Ling; Li, Jen-Ming; Hsu, Wen-Bin

doi:10.1128/jcm.41.7.3078-3088.2003

Cited by 12 publications

(12 citation statements)

References 18 publications

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“…It was not realized that these outbreaks were caused by different subtypes until the data from the NotI-based PFGE analyses were obtained. These findings demonstrate the usefulness of PFGE subtyping on the one hand (6,7,15) and suggest the potential existence of different subtypes in VNC all the time on the other.…”

Section: Pfge Typing and Dendrograms Of The S Flexneri Isolatesmentioning

confidence: 83%

“…Surprisingly, they belonged to either serotype 1a (20 strains) or serotype 4a (18 strains) ( Table 1). The records of the Center for Disease Control of Taiwan indicate that type 1a strains had not been found in western Taiwan in recent years (6,7), indicating that VNC might have been a reservoir for S. flexneri type 1a. Two points concerning the distribution of the serotypes were noticed (Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…However, new DNA molecular subtyping methods may further differentiate a serotype into molecular subtypes and facilitate analysis and tracing of the source of infections (6,7,23,24). NotI-based PFGE was previously shown (6, 7) to be a useful method for the molecular differentiation of S. flexneri strains isolated in Taiwan.…”

Section: Pfge Typing and Dendrograms Of The S Flexneri Isolatesmentioning

confidence: 99%

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Molecular Epidemiology ofShigella flexneriin a Long-Stay Psychiatric Nursing Center during 2001 to 2003

Lee

Liu

et al. 2005

J Clin Microbiol

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With six separate wards accommodating more than 1,600 patients, V Nursing Center (VNC) is a long-stay psychiatric nursing center in eastern Taiwan. During 2001 to 2003, 39 shigellosis cases occurred in VNC. Different from the notion that most cases of shigellosis are caused by Shigella sonnei, all except one of these cases were caused by S. flexneri, with the remaining one caused by an S. sonnei isolate. O-antigen serotyping showed that the 38 S. flexneri strains were of either type 1a (n ‫؍‬ 20) or 4a (n ‫؍‬ 18), two less prevalent serotypes in Taiwan. NotI-based pulsed-field gel electrophoresis analyses performed with 8 type 1a non-VNC strains and 9 type 4a non-VNC strains isolated from 1996 to 2003 for comparison divided the 28 type 1a strains and the 27 type 4a strains into 7 and 10 subtypes, designated subtypes P1A to P1G and subtypes P4A to P4J, respectively. Subtypes P1A and P4A, which appeared in three consecutive years in VNC as well as outside of VNC, are the most prevalent subtypes. Analyses of the relatedness of the VNC strains on the basis of the banding patterns grouped the type 1a and 4a strains into four and five clusters, respectively. All except one of the type 1a strains had 95% similarity, indicating that they had a common parent, whereas the type 4a strains had similarities that ranged from 77 to 93%, suggesting that they were of diverse origins. In two of the outbreaks, less related subtypes of the type 4a strains were found in the same VNC wards in consecutive years, suggesting the possible existence of different subtypes in VNC all the time. Antibiotic susceptibility testing showed that all except one of the S. flexneri strains were sensitive to at least seven antibiotics; the remaining isolate was sensitive to three antibiotics. The data from the latter tests should be helpful for selection of proper treatments for S. flexneri infections in Taiwan.

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Section: Pfge Typing and Dendrograms Of The S Flexneri Isolatesmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Pfge Typing and Dendrograms Of The S Flexneri Isolatesmentioning

confidence: 99%

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Molecular Epidemiology ofShigella flexneriin a Long-Stay Psychiatric Nursing Center during 2001 to 2003

Lee

Liu

et al. 2005

J Clin Microbiol

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“…The disease is highly contagious, with infectious doses of as low as 10–100 viable Shigella cells and an incubation period of 1–5 days. Large outbreaks of this disease typically occur in overcrowded areas with poor sanitary conditions or due to food or water that is contaminated by the pathogen [5-14]. Shigellosis transmission occurs primarily through person-to-person contact, most commonly among young children in households and populated institutes [15-17].…”

Section: Introductionmentioning

confidence: 99%

Infrequent cross-transmission of Shigella flexneri 2a strains among villages of a mountainous township in Taiwan with endemic shigellosis

Lin

Chiou

et al. 2013

BMC Infect Dis

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BackgroundShigellosis is rare in Taiwan, with an average annual incidence rate of 1.68 cases per 100,000 persons in 2000–2007. However, the incidence rate for a mountainous township in eastern Taiwan, Zhuoxi, is 60.2 times the average rate for the entire country. Traveling between Zhuoxi’s 6 villages (V1–V6) is inconvenient. Disease transmission among the villages/tribes with endemic shigellosis was investigated in this study.MethodsDemographic data were collected in 2000–2010 for epidemiological investigation. Thirty-eight Shigella flexneri 2a isolates were subjected to pulsed-field gel electrophoresis (PFGE) genotyping and antimicrobial susceptibility testing (AST).ResultsFifty-five shigellosis cases were identified in 2000–2007, of which 38 were caused by S. flexneri 2a from 2000–2007, 16 cases were caused by S. sonnei from 2000–2003, and 1 case was caused by S. flexneri 3b in 2006. S. flexneri 2a caused infections in 4 of the 6 villages of Zhuoxi Township, showing the highest prevalence in villages V2 and V5. PFGE genotyping categorized the 38 S. flexneri 2a isolates into 2 distinct clusters (clones), 1 and 2. AST results indicated that most isolates in cluster 1 were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and trimethoprim-sulfamethoxazole (ACSSuX); all isolates in cluster 2 were resistant to ACSSuX and tetracycline. Genotypes were primarily unique to different villages or tribes. Tribe V2-1 showed the highest endemic rates. Eighteen isolates recovered from V2-1 tribe members fell into 6 genotypes, where 5 were the same clone (cluster 1). An outbreak (OB2) in 2004 in village V2 was caused by different clonal strains; cases in tribe V2-1 were caused by 2 strains of clone 1, and those in tribe V2-2 were infected by a strain of clone 2.ConclusionsFrom 2000–2007, 2 S. flexneri 2a clones circulated among 4 villages/tribes in the eastern mountainous township of Zhuoxi. Genotyping data showed restricted disease transmission between the villages and tribes, which may be associated with difficulties in traveling between villages and limited contact between different ethnic aborigines. Transmission of shigellosis in this township likely occurred via person-to-person contact. The endemic disease was controlled by successful public health intervention.

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“…In Taiwan, S. sonnei was responsible for most of the large shigellosis outbreaks in the industrialized western area (13) and was frequently associated with imported infections (11). In contrast, S. flexneri was mainly circulating among the aboriginal tribes in the mountainous areas (5).…”

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confidence: 99%

Usefulness of Inter-IS 1 Spacer Polymorphisms for Subtyping of Shigella sonnei Isolates

et al. 2006

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Shigella sonnei contains numerous IS1 elements. The existence of polymorphisms in the length of the inter-IS1 spacer is a basis for the development of a PCR-based method for the subtyping of S. sonnei strains. The usefulness of inter-IS1 spacer typing (IST) was evaluated and compared with that of pulsed-field gel electrophoresis (PFGE) by characterization of S. sonnei isolates from epidemiologically nonrelated cases and outbreaks and of isolates that were indistinguishable by PFGE and that were collected from independent infection events. IST was less discriminatory than PFGE, with discriminatory indices of 0.96 and 0.63, respectively, but was able to compensate for the drawbacks of PFGE. PFGE exhibited a high level of discriminatory power for S. sonnei isolates; however, PFGE was also, at times, too discriminatory, which was a disadvantage in constructing the clonal relationships among strains circulating over a period of months or years. Furthermore, IST provided greater subtyping information for isolates indistinguishable by PFGE. The present study indicates that IST is more useful than PFGE for investigating the genetic relationships among S. sonnei strains circulating over a longer time span and also for discriminating certain strains which are indistinguishable by PFGE.Shigella sonnei is the most commonly isolated species among the four Shigella species in industrialized countries (8, 10) and also the predominant species responsible for travel-associated shigellosis (7). Shigellosis is relatively infrequent and is a designated notifiable disease in Taiwan, meaning that all shigellosis cases must be reported and that the Shigella isolates must be sent to the Centers for Disease Control of Taiwan (Taiwan CDC). During the period from 1993 to 2004, 61 to 1,357 (average, 388) cases of shigellosis cases were confirmed annually in Taiwan, a country with 23 million people (3). In Taiwan, S. sonnei was responsible for most of the large shigellosis outbreaks in the industrialized western area (13) and was frequently associated with imported infections (11). In contrast, S. flexneri was mainly circulating among the aboriginal tribes in the mountainous areas (5).Analyses of Shigella isolates by molecular subtyping methods can provide useful information on the outbreak and can help to trace the transmission and spread of the pathogen (6, 12). To date, several DNA-based methods have been developed for the subtyping of S. sonnei (14)(15)(16)18). Among the subytping methods, pulsed-field gel electrophoresis (PFGE) has been standardized and used in the laboratories of "PulseNet," a national molecular subtyping network for food-borne disease surveillance in the United States (19). The standardized PulseNet PFGE protocol (4) has been adopted by the Taiwan CDC and since 2003 has been used for the routine subtyping of Shigella species. PFGE has proven to be a powerful tool in our laboratory and others (1, 6) for discriminating Shigella strains for investigation of the outbreak. However, in our experience, PFGE is, in fact, at ...

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Molecular Epidemiology of Shigella in aTaiwan Township during 1996 to2000

Cited by 12 publications

References 18 publications

Molecular Epidemiology ofShigella flexneriin a Long-Stay Psychiatric Nursing Center during 2001 to 2003

Molecular Epidemiology ofShigella flexneriin a Long-Stay Psychiatric Nursing Center during 2001 to 2003

Infrequent cross-transmission of Shigella flexneri 2a strains among villages of a mountainous township in Taiwan with endemic shigellosis

Usefulness of Inter-IS 1 Spacer Polymorphisms for Subtyping of Shigella sonnei Isolates

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