Molecular epidemiology of shigella infections in Israel

Abstract

SUMMARYThe DNAs of Shigella sonnei or Shigella dysenteriae type 1 strains isolated in outbreaks of shigellosis or in sporadic cases were analysed by restriction fragment length polymorphism (RFLP). Southern blots of the DNAs of 36 S. sonnei isolates digested by 8 restriction enzymes were hybridized with an Escherichia coli rRNA probe. The S. sonnei strains were unexpectedly diverse in their RFLP. Antibiotypes of the same isolates showed clusters of strains corresponding to the various outbreaks. On the other hand, RFLP analysis suggested concomitant multiple sources of infection rather than a common source and thereby introduced a new insight in the epidemiology of shigellosis. RFLP was also used to trace S. dysenteriae type 1 transmission in a recent cluster of clinical cases. Although antibiotic resistance patterns indicated the presence of more than one strain, RFLP analysis showed that the six isolates were identical clones and suggested the loss of an R episome after one person-to-person passage.

Molecular epidemiology of Shigella flexneri in a diarrhoea-endemic area of Lima, Peru

“…Additionally, serological analysis cannot be considered alone since strains of the same serotype can be obtained from different geographical regions, which have been exposed to pressure-selection changes in both their phenotypic and genotypic properties [33]. Plasmid fingerprinting [33][34][35][36][37][38][39][40], antibiotic profiles [33,34,38,[40][41][42], analysis of the rRNA gene restriction patterns [43][44][45][46][47], phage typing [48,49], genomic DNA analysis by restriction fragment length polymorphism (RFLPs) [20,50], pulsed-field gel electrophoresis (PFGE) of DNA samples [32,35,45,51] and distribution of insertion sequences [32] have provided alternative techniques for shigella epidemiology. Individually, each assay has limitations.…”

“…The development of specific non-radioactive ipaH-related DNA probes to identify Shigella and EIEC has enabled investigators to determine the prevalence of these organisms in different populations, to identify mixed infection and rare serotypes, and to screen for Shigella and EIEC in large numbers of patients [16][17][18]. Additionally, the sensitivity and specificity of the polymerase chain reaction (PCR) for detection of DNA sequences specific to shigellae and EIEC, like the ipaH, virF and ial loci [15,[17][18][19][20] have indicated the importance of this technique in diagnostic and epidemiological shigella studies.…”