Survey of plasmid profiles of Shigella species isolated in Malaysia during 1994–2000

Abstract

Plasmid profiling was used to characterize 219 strains of Shigella species isolated from sporadic cases of shigellosis in Malaysia during the period 1994-2000. Heterogeneous plasmid patterns were observed in all Shigella spp. There was a correlation between plasmid patterns and serotypes of S. flexneri, S. dysenteriae and S. sonnei. Five common small plasmids (>20.0 kb) were observed in S. flexneri 1b and 2a, whereas six common small plasmids were found in serotype 3a. Some of these plasmids appeared to maintain their existence stably in each individual serotype. Plasmids of size 11.40 and 4.20 kb were present only in S. flexneri 2a isolates, whereas the 4.40 kb plasmid was unique for serotype 3a. Large (>150 kb) or mid-range plasmid (20.0-150 kb) was not observed from any S. flexneri 1b isolates. Eighty-nine percent of S. flexneri of various serotypes harboured the plasmid of 3.20 kb. All S. dysenteriae type 2 isolates harboured the 9.00 kb plasmid, while four common small plasmids were found in S. sonnei isolates. The 2.10 kb plasmid was only seen in S. sonnei. Streptomycin resistance in S. dysenteriae type 2 and multi-drug resistance in S. sonnei may be associated with the 9.00 and 14.8 kb plasmids, respectively. Plasmid profiling provided a further discrimination beyond serotyping and a useful alternative genotypic marker for differentiation of Shigella species. To the best of our knowledge, this is the first report on the plasmid prevalence of the Malaysian Shigella species.

Plasmid Profile Analysis and Antibiotic Resistance Patterns of Shigella Isolates from Kwale County, Kenya

“…This strongly suggests that these are core Shigella plasmids that constitute a stable gene pool and that can be used as preferred markers for identification of each of the corresponding serogroup in future epidemiological studies. Small plasmids of similar sizes were demonstrated in the previous studies in Malasyia (Hoe et al, 2005), in India (Dutta et al, 2002), in Peru (Fernandez-Prada et al, 2004 and in Iran (Shohreh et al, 2006). Significant statistical association was found between presence of middle range plasmids (48kb and 80kb) and MDR phenotype among the Shigella isolates.…”