title: Outbreak of dysentery associated with ceftriaxone-resistant Shigella sonnei: First report of plasmid-mediated CMY-2-type AmpC beta-lactamase resistance in S. sonnei.
abstract: We document the first report of plasmid-encoded CMY-2-type AmpC beta-lactamase identified among Shigella sonnei isolates resistant to ceftriaxone and obtained after an outbreak of bacillary dysentery in Taiwan. One hundred eighty-two children in two elementary schools in Yu-Li, Taiwan, where an outbreak occurred after a typhoon hit this area in 2001, were enrolled in this study. Clinical and epidemiologic data on the infected children were collected. Pulsed-field gel electrophoresis (PFGE) was performed on the isolates to determine the genetic relatedness of outbreak strains. Plasmid analysis and PCR were performed to identify beta-lactamase genes responsible for ceftriaxone resistance. Forty-seven children from the two elementary schools were culture positive for S. sonnei in this outbreak. Twenty-three children were asymptomatic. Of the total isolates 55.3% were resistant to ampicillin. One hundred percent of the isolates obtained from children in school A were initially susceptible to both ampicillin and ceftriaxone. Of isolates obtained from school B 96.2% were nonsusceptible to ceftriaxone. However, two isolates from school A developed resistance to ampicillin during the course of treatment. All 18 available isolates showed closely related PFGE patterns (4, 4a, 4b, and 4c). CMY-2-type AmpC beta-lactamase was responsible for ceftriaxone resistance in ceftriaxone-nonsusceptible isolates; Southern blot hybridization confirmed that such a resistance gene was located on the plasmid. This is the first report of plasmid-mediated CMY-2-type AmpC beta-lactamase in S. sonnei. Ampicillin-resistant isolates can develop during the course of antibiotic treatment.
authors.affiliation: Department of Pediatrics, Veterans General Hospital-Kaohsiung, 386, Ta-Chung 1st Road, Kaohsiung, Taiwan. chenchia@yahoo.com.
authors.forename: I-Fei
authors.initials: IF
authors.lastname: Huang
authors.forename: Cheng-Hsun
authors.initials: CH
authors.lastname: Chiu
authors.forename: Mei-Hui
authors.initials: MH
authors.lastname: Wang
authors.forename: Chan-Yao
authors.initials: CY
authors.lastname: Wu
authors.forename: Kai-Sheng
authors.initials: KS
authors.lastname: Hsieh
authors.forename: Christine C
authors.initials: CC
authors.lastname: Chiou
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002443:Ceftriaxone / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D012764:Shigella sonnei / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D013624:Taiwan / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002443:Ceftriaxone; C103022:beta-lactamase CMY-2; C048795:AmpC beta-lactamases; D001618:beta-Lactamases