Out of 1500 nasopharyngeal swab samples collected from patients who were admitted to different maternity clinics in Dhaka city, 111 optochin resistant strains were isolated. As a confirmatory test of Streptococcus pneumoniae, i.e., Bile solubility was checked. A total of 37 optochin resistant bile soluble isolates were obtained, designated as optochin resistant bile soluble S. pneumoniae as other - hemolytic streptococci are not bile soluble. For further identification, bile soluble isolates were subjected to PCR of the lytA gene specific for S. pneumonia an 32 (87%) isolates were found to be lytA positive. Thus, it can be suggested that for confirmatory identification of S. pneumoniae, bile solubility test together with PCR of lytA gene should be carried out in routine microbilogical investigation. Antimicrobial susceptibility test revealed multiple drug resistance among the organisms. About 64.86% were resistant to more than three agents (multi drug resistant). Higher MIC values were obtained for azithromycin ( 256 microg/ml), erythromycin ( 256 microg/ml) and ciprofloxacin ( 8 microg/ml) considering the CLSI break point.

Strains of Salmonella Paratyphi A isolated from the patients admitted to the diarrhoea treatment center of ICDDR, B were characterized both at the phenotypic and genotypic levels. Antibiotic susceptibility test revealed that 61% of the strains (n = 19) were sensitive to all the antibiotics used for empirical treatment of paratyphoid fever and 32% strains (n = 10) were resistant only to nalidixic acid. Most of the strains that showed reduced susceptibility to ciprofloxacin, having elevated MIC value (0.5ug/ml). A point mutation in the gyrA gene was observed at codon 83 (TCC to TTC), which substitutes phenylalanine for. This clearly indicates that a significant number of the S. Paratyphi A strains with reduced susceptibility to ciprofloxacin has been evolved. Of 31 strains, 16 (52%) of S. Paratyphi A strains harbored 35 MDa middle-ranged and non-conjugative plasmid. Pulse-field gel electrophoresis (PFGE) revealed that most of the strains (83%) were clonal regardless of antimicrobial sensitivity patterns.