Comparison of MGIT 960 & pyrazinamidase activity assay for pyrazinamide susceptibility testing of Mycobacterium tuberculosis.

Background & objectives: Pyrazinamide is an important front line antimycobacterial drug, which is also being used in the treatment of multi drug resistant tuberculosis along with second line drugs in DOTS plus programme. Conventional testing of pyrazinamide on solid medium is difficult as it is active at acidic pH. Therefore, there is a need for a rapid and simple method for susceptibility testing of pyrazinamide. This study was carried out to compare pyrazinamide susceptibility testing by MGIT 960 and two rapid pyrazinamidase activity tests. Methods: Pyrazinamide susceptibility was tested in 136 clinical isolates of Mycobacterium tuberculosis by MGIT 960 and pyrazinamidase activity was tested by classical Wayne’s method and modified PZase agar method. Results: There was 88.9 per cent concordance between MGIT 960 and classical Wayne’s method and 93.38 per cent with modified method for pyrazinamidase activity. Using MGIT 960 results as gold standard the sensitivity and specificity of Wayne’s method was 88.15 and 90 per cent respectively and that of modified method was 89.4 and 98.3 per cent. Interpretation & conclusions: Our study demonstrates that the modified pyrazinamidase activity test can be used as a screening test to detect resistance to pyrazinamide specially in resource limited settings but confirmation of susceptibility should be done by standard methods like MGIT 960.

Transport and storage of sputum specimen by using cetylpyridinium chloride for isolation of mycobacteria.

Of the 191 sputum specimens that were collected from pulmonary tuberculosis patients, 78.65% (140/178) specimens were culture positive when processed within 48 h by the NaOH method. The culture positivity in the same specimen that were stored with cetylpyridinium chloride (CPC) and processed after 7-8 days was 70.22% (125/178), whereas those stored without CPC and processed by the NaOH method was 46.62% (83/178). The difference in number of positive cultures obtained before storage and after storage (without CPC) was statistically significant (P = 0.001). Culture positivity by the CPC method was comparable with that of NaOH method before storage and the difference was not statistically significant (P = 0.35).

Prevalence of extended spectrum beta lactamase and AmpC beta lactamase producers among Escherichia coli isolates in a tertiary care hospital in Jaipur.

Resistance to broad spectrum beta lactams, mediated by extended spectrum beta lactamase (ESbetaL) and AmpC betaL enzymes is an increasing problem worldwide. Presence of these in clinical infections can result in treatment failure if one of the second or third generation cephalosporins is used. Therefore, it is recommended that any ESbetaL-producing organism according to the National Committee for Clinical Laboratory Standards (NCCLS) criteria can be reported as resistant to all extended spectrum beta lactam antibiotics regardless of the susceptibility test results. In this study, a total of 250 Escherichia coli (E. coli) isolates were subjected to Double disc test and AmpC disc test for the detection of ESbetaL- and AmpC betaL-producing strains, respectively. Prevalence of ESbetaL- and AmpC betaL-producing strains among E. coli isolates, over a 3-month-period in the hospital-based population of Jaipur, was 64.80% (162/250). AmpC betaL producers were 24.00% (60/250) and co-existence of ESbetaL and AmpC betaL was detected in 8.00% (20/250) of the isolates.

Enumeration of CD4 and CD8 T lymphocytes in healthy HIV seronegative adults of northwest India: a preliminary study.

CD4 T lymphocyte count is used to measure the progression of HIV infection and to monitor the response to antiretroviral therapy. Information on reference CD4 and CD8 T cell counts in healthy individuals is lacking in northwest India. Samples from 65 HIV-seronegative healthy volunteers (males, 37; females, 28) aged 18 through 59 years were analyzed using FACS (Fluorescent Antibody Cell Sorter) Count TM System. The values of mean and standard deviation of each lymphocyte subpopulation were estimated. The mean +/- SD of absolute numbers of CD4 and CD8 lymphocytes/microl was 743.4 +/- 307.8 and 541.7 +/- 176.4 in males and 790.7 +/- 280.4 and 497.03 +/- 203.6 in females respectively. The range of CD4 counts was 379 to 1800 in males and 321 to 1265 in females. The mean CD4:CD8 ratio was 1.43 +/- 0.56 in males and 1.78 +/- 0.76 in females. The results of this study show a wide variability in CD4 counts in the Indian population. A large multicentric study would define normal ranges of CD4, CD8, and CD4:CD8 ratios among the Indian population.