Genetic characterization of multidrug resistance in Shigella spp. from Japan.
This study characterized the genetic basis of antimicrobial resistance of a number of Shigella spp. isolated from humans from 2000 to 2004 in Hiroshima prefecture, Japan. A total of 26 isolates of Shigella spp. were included in this study. Antimicrobial susceptibility tests revealed high levels of resistance, especially to ampicillin, streptomycin, trimethoprim, tetracycline, nalidixic acid and ciprofloxacin. PCR and DNA sequencing were used for screening and characterization of antibiotic-resistance determinants. PCR sequencing analysis revealed the presence of only one type of class 1 integron in one isolate of Shigella sonnei. This class 1 integron was 1904 bp and contained two gene cassettes: a probable esterase/lipase (estX) and aadA1, which confers resistance to streptomycin and spectinomycin. Two types of class 2 integron were identified in this study. One was the classic type (2158 bp) and carried the three conserved resistance gene cassettes of the class 2 integron, dfrA1, sat1 and aadA1, which confer resistance to trimethoprim, streptothricin and streptomycin/spectinomycin, respectively. This type was detected in both Shigella sonnei (14 isolates) and Shigella flexneri (five isolates). The other type was shorter (1313 bp) and carried only two gene cassettes, dfrA1 and sat1. This integron was detected in a single isolate of Shigella sonnei. PFGE patterns showed limited diversity within clusters of the same species. Furthermore, an extended-spectrum beta-lactamase gene, bla(OXA-30), which confers resistance to ampicillin, was characterized in all isolates of Shigella flexneri except the oldest strain, which was isolated in 2000. Southern blot hybridization and conjugation experiments showed that bla(OXA-30) was located in the chromosome.
Ahmed
Ashraf M
AM
Department of Microbiology, Faculty of Veterinary Medicine, Kafr El-Sheikh University, Kafr El-Sheikh 33516, Egypt.|Laboratory of Food Microbiology and Hygiene, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
Furuta
Kimi
K
Division of Biological Science, Hiroshima City Institute of Public Health, Hiroshima 733-8650, Japan.
Shimomura
Kei
K
Division of Biological Science, Hiroshima City Institute of Public Health, Hiroshima 733-8650, Japan.
Kasama
Yoshio
Y
Division of Biological Science, Hiroshima City Institute of Public Health, Hiroshima 733-8650, Japan.
Shimamoto
Tadashi
T
Laboratory of Food Microbiology and Hygiene, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
D000890:Anti-Infective Agents / Q000494:pharmacology; D004269:DNA, Bacterial; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004405:Dysentery, Bacillary / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D006801:Humans; D032023:Integrons / Q000235:genetics; D007564:Japan; D008969:Molecular Sequence Data; D017421:Sequence Analysis; D012760:Shigella / Q000187:drug effects / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics
D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D001618:beta-Lactamases