Comparison between IS6110 and MPB64 primers for the diagnosis of Mycobacterium tuberculosis in Bangladesh by polymerase chain reaction (PCR).

The study was carried out to evaluate the efficacy of two different primers in PCR based diagnosis of tuberculosis on the basis of the time involvement, steps of PCR, cost and accuracy of results. Among 17 clinically suspected pulmonary tuberculosis patient's (M:F 65:35) sputum samples, 12 were found positive by both primers. Among 81 routine samples (sputum = 12; blood = 27; cerebrospinal fluid = 16; ascitic fluid = 12 and urine = 14), 12 were found to be positive by IS6110 primer while 13 were found positive by MPB64. The result of M. tuberculosis DNA PCR in sputum, ascitic fluid, CSF and urine samples were found to be similar in both the primers used. It is suggested that, M. tuberculosis DNA PCR in blood samples using MPB64 primers sometime gives false positive result and therefore, may not be recommended for blood samples. As in other samples both the primers gave almost the same result and therefore, both the primers can be used for MTB DNA PCR vice versa in order to cross check if one gives dubious result.

Predominance of the DEN-3 genotype during the recent dengue outbreak in Bangladesh.

A recent outbreak of dengue in Bangladesh was marked by many fatal complications. As clinical virulence varies among the genotypes of dengue virus, a study was conducted to investigate the molecular genotypes of dengue in Bangladesh. Reverse transcription polymerase chain reaction was used to determine viral genotypes using oligonucleotide generic primers that produce a 511 bp product. The resulting product was typed by nested PCR with strain-specific primers, yielding 482 (DEN-1), 119 (DEN-2), 290 (DEN-3) and 392 (DEN-4), visualized on UV transilluminator after electrophoresis on 2% agarose gel stained with ethidium bromide. Of 45 clinically diagnosed dengue patients (mean age 28 years; male/female 30/15), 19 (42.2%) had detectable viral RNA in their blood. However, during the first 5 days of fever in 30 patients, the frequency was 60% (18/30), implying that the sooner serum is drawn after the fever, the greater the chances of detecting viral RNA. DEN-3 was detected in all except 2 patients who were infected with DEN-2. DEN-2 (two cases) and DEN-4 (one case) were present as co-infections with DEN-3. All of the patients presented with fever, anorexia and vomiting; many had headache and general body ache; a few had a rash. About a quarter had suffered episodes of bleeding, while ascites, pleural effusion and CNS symptoms were found in a few patients Patients positive for viral RNA were also positive for anti-dengue IgM (p=0.007) in subsequent sampling. The study suggests the predominance of DEN-3 infection with occasional co-infection with other types, during the recent outbreak of dengue in Bangladesh.