Spatio-temporal study of environmental nontuberculous mycobacteria isolated from Wardha district in Central India.

During the last two decades, nontuberculous mycobacteria (NTM) have gained in importance but there is still a paucity of data, particularly for environmental isolates. We studied, over a period of two years, the spatio-temporal features of NTM isolates obtained from different environmental sources in Wardha district, India. A total of 1398 samples (699 each of soil and water) were tested and 170 (12.2%) yielded NTM isolates, including 123 from soil and 47 from water samples. Out of 170 NTM isolates, 107 (63%) belonged to potentially pathogenic mycobacteria (PPM) and 63 (37%) to the less pathogenic mycobacterial (LPM) group. Overall, maximum isolation was obtained in rainy season (20.3%) followed by winter (13.5%), post rainy (8.7%) and summer seasons (5.8%). Mycobacterium fortuitum, Mycobacterium gordonae and Mycobacterium avium complex (MAC) were common isolates followed by Mycobacterium flavescens, Mycobacterium scrofulaceum, Mycobacterium simiae and Mycobacterium marinum. From soil, isolation of NTM was highest from grounds used for community gatherings (42.8%) followed by soil from residential premises (27.7%) and near the wells (26.0%). From drinking water sources, highest NTM isolation was obtained from wells (15.4%) followed by treated water tanks (6.9%), household receptacles (6.3%), hand pumps (5.6%) and tap water supply (3.5%). Isolation from natural canal water was 6.6%, while from drainage and waste water ponds isolation was 8.3%. The results of the study revealed that in Wardha district, NTM are present both in the soil and drinking water. As NTM can be pathogenic, particularly in immune-compromised individuals, these can be of potential risk to the human population.

ICEVchInd5 is prevalent in epidemic Vibrio cholerae O1 El Tor strains isolated in India.

Integrative conjugative elements (ICEs) of the SXT/R391 family are self-transmissible mobile elements mainly involved in antibiotic resistance spread among γ-Proteobacteria, including Vibrio cholerae. We demonstrated that the recently described ICEVchInd5 is prevailing in V. cholerae O1 clinical strains isolated in Wardha province (Maharashtra, India) from 1994 to 2005. Genetic characterization by ribotyping and multiple-locus SSR analysis proved the same clonal origin for V. cholerae O1 isolates in Wardha province over an 11-year period and was used to assess the correlation between strain and ICE content among ours and different Indian reference strains. In silico analysis showed the existence of at least 3 sibling ICEs of ICEVchInd5 in V. cholerae O1 El Tor reference strains, isolated in the Indian subcontinent after 1992.

Mycobacterium tuberculosis infection in health care workers in rural India: comparison of a whole-blood interferon gamma assay with tuberculin skin testing.

CONTEXT: Mycobacterium tuberculosis infection in health care workers has not been adequately studied in developing countries using newer diagnostic tests. OBJECTIVES: To estimate latent tuberculosis infection prevalence in health care workers using the tuberculin skin test (TST) and a whole-blood interferon gamma (IFN-gamma) assay; to determine agreement between the tests; and to compare their correlation with risk factors. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional comparison study of 726 health care workers aged 18 to 61 years (median age, 22 years) with no history of active tuberculosis conducted from January to May 2004, at a rural medical school in India. A total of 493 (68%) of the health care workers had direct contact with patients with tuberculosis and 514 (71%) had BCG vaccine scars. INTERVENTIONS: Tuberculin skin testing was performed using 1-TU dose of purified protein derivative RT23, and the IFN-gamma assay was performed by measuring IFN-gamma response to early secreted antigenic target 6, culture filtrate protein 10, and a portion of tuberculosis antigen TB7.7. MAIN OUTCOME MEASURES: Agreement between TST and the IFN-gamma assay, and comparison of the tests with respect to their association with risk factors. RESULTS: A large proportion of the health care workers were latently infected; 360 (50%) were positive by either TST or IFN-gamma assay, and 226 (31%) were positive by both tests. The prevalence estimates of TST and IFN-gamma assay positivity were comparable (41%; 95% confidence interval [CI], 38%-45% and 40%; 95% CI, 37%-43%, respectively). Agreement between the tests was high (81.4%; kappa = 0.61; 95% CI, 0.56-0.67). Increasing age and years in the health profession were significant risk factors for both IFN-gamma assay and TST positivity. BCG vaccination had little impact on TST and IFN-gamma assay results. CONCLUSIONS: Our study showed high latent tuberculosis infection prevalence in Indian health care workers, high agreement between TST and IFN-gamma assay, and similar association between positive test results and risk factors. Although TST and IFN-gamma assay appear comparable in this population, they have different performance and operational characteristics; therefore, the decision to select one test over the other will depend on the population, purpose of testing, and resource availability.

Prevalence of pulmonary tuberculosis in Wardha district of Maharashtra, Central India.

A house based survey was conducted during 2007-2009 in a representative sample of population in Wardha district implementing Directly Observed Treatment Short Course strategy for tuberculosis (TB) control since 2001. The objective was to estimate prevalence of bacillary pulmonary TB (PTB) in individuals aged 15 years or above, and to estimate trends in prevalence when compared to a previous survey carried out in mid 1980's. Two sputum samples (one spot, one early morning) collected from individuals having symptoms suggestive of PTB, history of previous anti-TB treatment (ATT) or abnormal pulmonary shadow on Mass Miniature Radiography (MMR) consistent with possibly or probably active tuberculosis were subjected to Ziehl-Neelsen microscopy and culture on Lowenstein-Jensen medium. Of 55,096 individuals registered into the survey, 50,332 (91.4%) were screened by interview for symptoms and history of ATT and/or by MMR. Of them, 4805 were eligible for sputum collection; both specimens were collected in 4285 (89.2%) and only one specimen in 27 (0.6%). A total of 86 bacillary cases were detected during the survey. Prevalence of bacillary PTB was estimated at 188.7 (140.3-236.9) per 100,000 populations. There was a decline of 61% in the prevalence of PTB over a period of 22 years.

Successful treatment of peritonitis by C. bertholletiae in a chronic kidney failure patient on continuous ambulatory peritoneal dialysis after kidney rejection.

Peritonitis is a common problem in patients undergoing peritoneal dialysis. However, peritonitis due to Cunninghamella (C.) bertholletiae, a fungus of the class Zygomycetes, is rare. We present a case of fungal peritonitis in a patient on continuous ambulatory peritoneal dialysis due to kidney rejection. Direct examination of the patient's peritoneal fluid showed fungal hyphae, and the culture was identified as C. bertholletiae. A cumulative dose of 1,600 mg fluconazole was given to the patient intraperitoneally over a one-week period. When his condition had stabilised, oral antifungal treatment was administered for two weeks. After removal of the Tenckhoff catheter, the patient was discharged with arteriovenous fistulation for haemodialysis. Zygomycosis due to C. bertholletiae is often fatal and non-responsive to systemic antifungal therapy. This case is the first from India with a successful outcome, and highlights the importance of early detection and intervention for successful outcome of peritonitis caused by C. bertholletiae.

Comparison of a whole blood interferon-gamma assay with tuberculin skin testing for the detection of tuberculosis infection in hospitalized children in rural India.

OBJECTIVE: In vitro interferon-gamma (IFN-gamma) assays have emerged as novel alternatives to the tuberculin skin test (TST) for the diagnosis of latent tuberculosis (TB) infection. These assays have been evaluated in low incidence countries, mainly in adults, and have been shown to be more specific than TST. Because few studies have been done in high incidence countries, and because paediatric data are limited, we compared a whole-blood IFN-gamma assay with TST among hospitalized Indian children. METHODS: Between July 2004 and June 2005, a total of 105 consecutively admitted children (median age 6 years; 82% had BCG scars) in whom TB was suspected or had history of contact with an index case were recruited at a rural hospital in India. All children underwent TST, and the QuantiFERON-TB-Gold In Tube (QFT) assay. RESULTS: The overall prevalence of TB infection was similar with both tests. With a TST cut-off point of > or =10mm, 10 of 105 (9.5%; 95% CI 3.8, 15.2) children were TST positive. With a cut-off point of IFN-gamma> or =0.35IU/ml, 11 of 105 (10.5%; 95% CI 4.5, 16.4) were QFT positive. The concordance between TST and QFT was substantial (agreement 95.2%; kappa [kappa] 0.73; 95% CI for kappa 0.53, 0.92). Agreement between TST and QFT results was 100% (kappa 1.0) in BCG scar-negative children as compared to 94% (kappa 0.63) in scar-positive children. BCG was not associated with the results of either TST or QFT (P>0.05 for both tests). The number of children with bacteriologically confirmed active TB was too small to permit the estimation of sensitivity of the tests. CONCLUSIONS: In a rural, predominantly BCG-vaccinated paediatric population in India, the TST and QFT assay produced comparable results. BCG vaccination did not significantly affect either TST or QFT results. Larger studies are needed to compare the sensitivity of the IFN-gamma assay with that of the TST in children with bacteriologically and/or clinically confirmed TB.

Persistently elevated T cell interferon-gamma responses after treatment for latent tuberculosis infection among health care workers in India: a preliminary report.

BACKGROUND: T cell-based interferon-gamma (IFN-gamma) release assays (IGRAs) are novel tests for latent tuberculosis infection (LTBI). It has been suggested that T cell responses may be correlated with bacterial burden and, therefore, IGRAs may have a role in monitoring treatment response. We investigated IFN-gamma responses to specific TB antigens among Indian health care workers (HCWs) before, and after LTBI preventive therapy. METHODS: In 2004, we established a cohort of HCWs who underwent tuberculin skin testing (TST) and a whole-blood IGRA (QuantiFERON-TB-Gold In-Tube [QFT-G], Cellestis Ltd, Victoria, Australia) at a rural hospital in India. HCWs positive by either test were offered 6 months of isoniazid (INH) preventive therapy. Among the HCWs who underwent therapy, we prospectively followed-up 10 nursing students who were positive by both tests at baseline. The QFT-G assay was repeated 4 and 10 months after INH treatment completion (i.e. approximately 12 months and 18 months after the initial testing). IFN-gamma responses to ESAT-6, CFP-10 and TB7.7 peptides were measured using ELISA, and IFN-gamma >/=0.35 IU/mL was used to define a positive QFT-G test result. RESULTS: All participants (N = 10) reported direct contact with smear-positive TB patients at baseline, during and after LTBI treatment. All participants except one started treatment with high baseline IFN-gamma responses (median 10.0 IU/mL). The second QFT-G was positive in 9 of 10 participants, but IFN-gamma responses had declined (median 5.0 IU/mL); however, this difference was not significant (P = 0.10). The third QFT-G assay continued to be positive in 9 of 10 participants, with persistently elevated IFN-gamma responses (median 7.9 IU/mL; P = 0.32 for difference against baseline average). CONCLUSION: In an environment with ongoing, intensive nosocomial exposure, HCWs had strong IFN-gamma responses at baseline, and continued to have persistently elevated responses, despite LTBI treatment. It is plausible that persistence of infection and/or re-infection might account for this phenomenon. Our preliminary findings need confirmation in larger studies in high transmission settings. Specifically, research is needed to study T cell kinetics during LTBI treatment, and determine the effect of recurrent exposures on host cellular immune responses.

Serial testing of health care workers for tuberculosis using interferon-gamma assay.

RATIONALE: Although interferon-gamma (IFN-gamma) assays are promising alternatives to the tuberculin skin test (TST), their serial testing performance is unknown. OBJECTIVE: To compare TST and IFN-gamma conversions and reversions in healthcare workers. METHODS: We prospectively followed-up 216 medical and nursing students in India who underwent baseline and repeat testing (after 18 mo) with TST and QuantiFERON-TB Gold In-Tube (QFT). TST conversions were defined as reactions greater than or equal to 10 mm, with increments of 6 or 10 mm over baseline. QFT conversions were defined as baseline IFN-gamma less than 0.35 and follow-up IFN-gamma greater than or equal to 0.35 or 0.70 IU/ml. QFT reversions were defined as baseline IFN-gamma greater than or equal to 0.35 and follow-up IFN-gamma less than 0.35 IU/ml. RESULTS: Of the 216 participants, 48 (22%) were TST-positive, and 38 (18%) were QFT-positive at baseline. Among 147 participants with concordant baseline negative results, TST conversions occurred in 14 (9.5%; 95% confidence interval [CI] = 5.3-15.5) using the 6 mm increment definition, and 6 (4.1%; 95% CI = 1.5-8.7) using the 10 mm increment definition. QFT conversions occurred in 17/147 participants (11.6%; 95% CI = 6.9-17.9) using the definition of IFN-gamma greater than or equal to 0.35 IU/ml, and 11/147 participants (7.5%; 95% CI = 3.8-13.0) using IFN-gamma greater than or equal to 0.70 IU/ml. Agreement between TST (10 mm increment) and QFT conversions (>or= 0.70 IU/ml) was 96% (kappa = 0.70). QFT reversions occurred in 2/28 participants (7%) with baseline concordant positive results, as compared with 7/10 participants (70%) with baseline discordant results (p < 0.001). CONCLUSIONS: IFN-gamma assay shows promise for serial testing, but repeat results need to be interpreted carefully. To meaningfully interpret serial results, the optimal thresholds to distinguish new infections from nonspecific variations must be determined.