Molecular analysis of virulence plasmids of invasive shigella species

A total of 48 isolates of Shigella species obtained from the Military Central Laboratories was examined for serotype, antibiotic resistance and invasiveness. The transferability and molecular structure of the virulence plasmids from each isolate were also examined. Twenty strains were evasive and 70% of these virulent strains were multidrug resistant. Ten virulent strains [tra+] transferred ampicillin resistance and virulence simultaneously, i.e. they carried conjugative plasmids; while the other strains [10 strains] were tra-. By plasmid analysis and DNA homology, almost all the virulent strains carried a large plasmid of 230 Kb, and 2-3 small cryptic plasmids [6.4, 3.3 and 2.7 Kb]. The results suggested that the cryptic plasmids can be transferred to other strains of the same species by conjugation or mobilization, predicting that the virulent multidrug resistant strains may no longer be restricted to a narrow range of serotypes in the near future. Further genetic analysis of virulence plasmids may be essential for the development of recombinant vaccines against Shigella species

Rapid identification of mycobacterium tuberculosis from meningitis cases

Fifty acid-fast bacilli isolated from clinically diagnosed meningitis patients at Zagazig Fever Hospital were identified by both the st and ard method and the 5 hours assay method [API- ZYM strip plus 5 additional tests]. All the 50 strains were identified as Myco. tuberculosis by the two methods. Seventeen different profiles were found through the API- ZYM scheme, which would provide epidemiological markers. Comparing the two methods, the API - ZYM based scheme method was found to be easy to set-up, rapid, cheap and applicable. However, inconsistent biochemical reactions were noted when the strains were allowed to grow in excess for 25 days on L. J. slants, due to a decrease in the detectable enzyme production. Forty-three of the Myco. tuberculosis strains were identified correctly, 5 [10%] were questionable [suggesting Myco. bovis] and 2 [4%] strains did not code out as a species. When the 50 strains were included for 20-25 days, all parameters were positive for Myco. tuberculosis. Moreover, the antimicrobial resistance patterns of these 50 strains were performed to be correlated with the 19 enzymatic activities of the API - ZYM system, but no correlation was proved