Epidemiologic relationship between fluoroquinolone-resistant Salmonella enterica Serovar Choleraesuis strains isolated from humans and pigs in Taiwan (1997 to 2002).
The emergence of ciprofloxacin-resistant Salmonella enterica serovar Choleraesuis in recent years has become an important public health issue in Taiwan. The resistant strains that cause human infections are considered to be from pigs. In this study, we characterized 157 swine and 42 human Salmonella serovar Choleraesuis isolates by pulsed-field gel electrophoresis (PFGE) and drug susceptibility testing to investigate the epidemiologic relationship among the isolates. By PFGE analyses, two major clusters (clusters GA and GB) were identified. Isolates in cluster GA were of both human and swine origins, while those in cluster GB were from pigs only. Among the various genotypes identified, genotype gt-1a was the most prevalent, which was found in 71% (30 of 42) and 48% (76 of 157) of human and swine isolates, respectively. The susceptibility tests for the 106 gt-1a isolates identified 44 susceptibility profiles and showed that 73% of human isolates and 34% of swine isolates were resistant to three fluoroquinolones (ciprofloxacin, enrofloxacin, and norfloxacin). Our findings indicate that a clonal group of Salmonella serovar Choleraesuis may have been circulating in human and swine populations in Taiwan for years and that the fluoroquinolone-resistant Salmonella serovar Choleraesuis strains most likely evolved from a gt-1a clone that emerged in 2000 and that then caused widespread infections in humans and pigs. Nevertheless, it is still debatable whether those Salmonella infections in humans are caused by isolates derived from pigs, on the basis of the higher fluoroquinolone and other antimicrobial resistance percentages in human isolates than in pig isolates.
Chang
Chao-Chin
CC
Graduate Instituteof Veterinary Public Health, National Chung Hsing university, Taichung 402, Taiwan.
Lin
Yi-Hsuan
YH
Chang
Chao-Fu
CF
Yeh
Kuang-Sheng
KS
Chiu
Cheng-Hsun
CH
Chu
Chishih
C
Chien
Maw-Sheng
MS
Hsu
Yuan-Man
YM
Tsai
Li-Shu
LS
Chiou
Chien-Shun
CS
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology; D012481:Salmonella Infections, Animal / Q000453:epidemiology / Q000382:microbiology; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013552:Swine / Q000382:microbiology; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology; D013624:Taiwan / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones