Molecular epidemiology of Salmonella enterica serovar Enteritidis isolated in Taiwan.
Incidence of Salmonella enterica serovar Enteritidis infection seems to be on the rise in Taiwan, and therefore, the characteristics of the isolate, including genotypes, were epidemiologically investigated. Of the 71 clinical strains isolated in 1997-1999, 61 (86%) remained susceptible to the eight antibiotics tested, while the remaining ten, eight of which were isolated in 1999, were resistant to one to three of the agents including three multiply resistant strains. The majority, 69 or 97% of the isolates, harbored a 60-kb spvC gene-carrying virulence plasmid and 12 of them harbored one or two additional various-sized plasmids. Strains with more than one plasmid were isolated mostly in 1999. Pulse-field gel electrophoresis (PFGE) revealed three major genotypes (Types A, B and C), in which type A was the predominant type. Of the 68 Type A, which contained 8 subtypes, 59 (83%) belonged to only two subtypes. Similar results were obtained with a PCR-based typing method, the infrequent-restriction-site (IRS) PCR. All four methods detected types that were rarely seen before and most of these were of recent isolates, indicating that these unusual types were new or strains of foreign origin. Though all four methods discriminated types well, PFGE and IRS-PCR showed higher sensitivity for classification. Between the two, the latter, though less discriminatory than PFGE, seems the method of choice, since it is simpler, less time-consuming and above all easy to perform.
Su
Lin-Hui
LH
Department of Clinical Pathology, Chang Gung Memorial Hospital, Kweishan, 333, Taoyuan, Taiwan.
Chiu
Cheng-Hsun
CH
Wu
Tsu-Lan
TL
Chu
Chishih
C
Chia
Ju-Hsin
JH
Kuo
An-Jing
AJ
Lee
Chia-Ching
CC
Sun
Chien-Feng
CF
Ou
Jonathan T
JT
D016172:DNA Fingerprinting; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005243:Feces / Q000382:microbiology; D006801:Humans; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology; D012477:Salmonella enteritidis / Q000235:genetics* / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D013624:Taiwan / Q000453:epidemiology; D014774:Virulence