Clinical evaluation of the mycobacteriophage-based assay in rapid detection of Mycobacterium tuberculosis in respiratory specimens.

CONTEXT: Search for a cost-effective, rapid and accurate test has renewed interest in mycobacteriophage as a tool in the diagnosis of tuberculosis (TB). There has been no reported data on the performance of phage assay in a high burden, low-resource setting like Kanpur city, India. AIMS: To assess the sensitivity and specificity of the FASTPlaque TB kit ability to impact the bacillary load in the phage assay and its performance in the sputum smear sample negative cases. MATERIALS AND METHODS: The study involved a cross-sectional blinded assessment of phage assay using the FASTPlaque TB kit on 68 suspected cases of pulmonary TB against sputum smear microscopy by Ziehl-Neilsen staining and culture by the LJ method. RESULTS: The sensitivity, specificity and positive and negative predictive values of the phage assay were 90.7, 96, 97.5 and 85.7%, respectively. The assay was negative in all the five specimens growing mycobacteria other than TB. The sensitivity of the phage assay tended to decrease with the bacillary load. Of the smear-negative cases, three were false negative, and all of which were detected by the phage assay. Smear microscopy (three smears per patient) had a sensitivity and specificity of 93 and 64%, respectively. CONCLUSIONS: The phage assay has the potential clinical utility as a simple means of rapid and accurate detection of live Mycobacterium tuberculosis bacilli; however, its performance has been inconsistent across various studies, which highlights that the assay requires a high degree of quality control demanding infrastructure and its performance is vulnerable to common adversities observed in "out of research" practice settings like storage, transport and cross-contamination.

Prevalence and risk factors for bronchial asthma in Indian adults: a multicentre study.

BACKGROUND: There is limited information on field epidemiology of bronchial asthma in Indian adults. OBJECTIVES: To estimate prevalence of bronchial asthma in different regions of India and to define risk factors influencing disease prevalence. METHODS: A field study was conducted at Chandigarh, Delhi, Kanpur and Bangalore through a two stage stratified (urban/ rural) sampling and uniform methodology using a previously validated questionnaire. Asthma was diagnosed if the respondent answered affirmatively both to (a) whistling sound from chest, or chest tightness, or breathlessness in morning, and (b) having suffered from asthma, or having an attack of asthma in the past 12 months, or using bronchodilators. Besides demographic data, information on smoking habits, domestic cooking fuel used, atopic symptoms, and family history suggestive of asthma was also collected. Univariate and multivariate logistic regression modelling was performed to calculate odds ratio of various potential risk factors. RESULTS: Data from 73605 respondents (37682 men, 35923 women) were analysed. One or more respiratory symptoms were present in 4.3-10.5% subjects. Asthma was diagnosed in 2.28%, 1.69%, 2.05 and 3.47% respondents respectively at Chandigarh, Delhi, Kanpur and Bangalore, with overall prevalence of 2.38%. Female sex, advancing age, usual residence in urban area, lower socio-economic status, history suggestive of atopy, history of asthma in a first degree relative, and all forms of tobacco smoking were associated with significantly higher odds of having asthma. CONCLUSION: Prevalence estimates of asthma in adults in this study, although lower than several previously reported figures, point to a high overall national burden of disease.

A multicentric study on epidemiology of chronic obstructive pulmonary disease and its relationship with tobacco smoking and environmental tobacco smoke exposure.

INTRODUCTION: Population prevalence of chronic obstructive pulmonary disease (COPD) and its relationship with tobacco smoking, environmental tobacco smoke (ETS) exposure and other variables were studied in adult subjects of 35 years and above at four different centres in India. Question-items for the diagnosis of COPD were included in the questionnaire used for the field study on asthma epidemiology. METHODS: Field surveys were conducted in both the urban and the rural populations at Bangalore, Chandigarh, Delhi and Kanpur with the help of a structured and validated questionnaire for diagnosis of asthma and COPD. Separate sets of questions were used for the diagnoses of the two diseases. A two-stage stratified sample design was employed where a village or an urban locality formed the first stage unit and a household formed the second stage unit. A uniform methodology was used at all the four centres and the analyses were done at the central coordinating centre--Chandigarh. Chronic obstructive pulmonary disease, defined by chronic bronchitis (CB) criteria, was diagnosed from the presence of cough and expectoration on most of the days for at least three months in a year for two consecutive years or more. RESULTS: Chronic obstructive pulmonary disease was diagnosed in 4.1% of 35295 subjects, with a male to female ratio of 1.56:1 and a smoker to nonsmoker ratio of 2.65: 1. Prevalence among bidi and cigarette smokers was 8.2% and 5.9%, respectively. Odds ratio (OR) for COPD was higher for men, elderly individuals, lower socio-economic status and urban (or mixed) residence. Environmental tobacco smoke exposure among nonsmokers had an OR of 1.4(95% CI 1.21-1.61). Combined exposure to both ETS and solid fuel combustion had higher OR than for ETS exposure alone. CONCLUSIONS: Population prevalence of COPD is very high in India with some centre to centre differences. Smoking of both bidis and cigarettes, and ETS exposure among nonsmokers, were two important risk factors at all centres. It is important to employ uniform methodology for assessment of national burden and disease-surveillance programme.

Household environmental tobacco smoke exposure, respiratory symptoms and asthma in non-smoker adults: a multicentric population study from India.

BACKGROUND: Exposure to environmental tobacco smoke (ETS) is a risk factor for childhood asthma. Its association with asthma in adults is less clear. METHODS: In a multicentric population study on asthma prevalence in adults, specific enquiries were made into childhood and adulthood exposure to household ETS, and its relationship with asthma diagnosis were analysed. RESULTS: From a total of 73605 respondents, 62109 were studied after excluding current or past smokers. Overall observed prevalence of asthma was 2.0% (men 1.5%,women 2.5%, p < 0.001). Of all asthma patients, history of ETS exposure was available in 48.6 percent. Prevalence of asthma in the ETS exposed subjects was higher compared to non-exposed individuals (2.2% vs 1.9%, p < 0.05). Multiple logistic regression analysis showed a higher risk of having asthma in persons who were exposed to ETS compared to those not exposed (odds ratio [OR] 1.22, 95% CI 1.08-1.38) after adjusting for age, gender, usual residence, exposure to biomass fuels and atopy. Stratification of ETS exposure revealed that exposure during childhood and both during childhood and adulthood were significantly associated with asthma prevalence. Exposure only in adulthood was not a significant risk factor (OR 1.13, 95% CI 0.95-1.33). Persons reporting combined environmental tobacco smoke exposure from parents during childhood and spouse during adulthood had highest risk of having asthma (OR 1.69, 95% CI 1.38-2.07). Environmental tobacco smoke exposure was also significantly associated with prevalence of respiratory symptoms such as wheezing, cough and breathlessness. CONCLUSIONS: Environmental tobacco smoke exposure during childhood is an important risk factor for asthma and respiratory symptoms in non-smoking adults.

Tobacco smoking in India: prevalence, quit-rates and respiratory morbidity.

BACKGROUND: Population prevalence of tobacco smoking especially with reference to detailed habits such as the amount smoked, the smoking forms, quit-rates and relationship with demographic variables were studied at four different centres in India along with the study on epidemiology of asthma and chronic obstructive pulmonary disease. METHODS: The study population included adults of over 15 years of age selected with two-stage stratified random sample design. A specifically designed questionnaire was used for the study. RESULTS: There were 11496 (15.6%) ever smokers in the study sample of 73605 subjects. Among 37682 males, 10756 (28.5%) were ever smokers and among 35923 females, 740 (2.1%) were ever smokers. Bidi was the commonest form of smoking, more so in the rural areas. The mean number of cigarettes/bidis smoked per day was 14 (+/- 11.5) and the mean age of starting smoking was 20.5 (+/- 20.0) years. Increasing age, low socio-economic status and rural residence were important factors associated with smoking. Vigorous anti-tobacco measures under the tobacco control programmes yielded only a quit-rate of 10 percent. Nearly 14% of ever smokers had some respiratory symptoms. CONCLUSIONS: A substantial proportion of population in India has current or past smoking habit with higher prevalence among males than females. The quit-rates have been low in spite of the various anti-tobacco measures. There is a significant respiratory morbidity associated with smoking.

Cultivation of Mycobacterium tuberculosis from pleural tissue and its histopathology in suspected cases of tuberculous pleural effusion.

The majority of idiopathic pleural effusion are considered to be of tuberculous etiology. The culture of bacilli provide most authentic evidence of disease process. This study was carried out on 21 cases of suspected tuberculous pleural effusion. The pleural fluid and tissue was subjected for smear examination, and cultivation of tubercle bacilli along with pleural biopsy. Overall the diagnosis could be made out of 8 (38.09%) cases. The cultivation of Mycobacterium tuberculosis from pleural tissue was more sensitive (33.33%) as compared to histopathology (19.05%). However, the triad of cultivation of Mycobacterium tuberculosis from pleural tissue, pleural histopathology and pleural fluid smear examination or culture should be done in each suspected case of tuberculous effusion.

Conservative management of empyema thoracis and broncho-pleural fistula.

One hundred and eight cases of empyema with and without broncho pulmonary fistula (BPF) were studied to analyse the efficacy of conservative management (aspiration/s and/or ICD). It was successful in 87.04% cases. Among those treated with intercostal drainage, the tube was removed within 2 months in 61.22%, 5 months in 71.42%, and 24 months in 85.71% cases. Only 14.29% cases showed persistent air leak even after 2 years of closed drainage. It was concluded that all cases of simple empyema and most cases of empyema with BPF can be managed successfully with conservative methods including aspirations and closed intercostal tube drainage.

Virulence of Giardia lamblia: an in vitro study on host-parasite interaction.

Trophozoites of G. lamblia, a human parasite, were lysed by polymorphonuclear leukocytes (PMNL) of healthy individuals during in vitro interaction. However, the parasite damaged PMNL of giardiasis patients. A prior treatment of giardia trophozoites with anti-giardia serum, caused agglutination of pathogen and, thereby, the cytotoxic capacity of the parasite was reduced. Interaction of giardia-trophozoites with peritoneal macrophage, derived from infected mouse, reduced the phagocytic activity of the latter to 43% (against 100% in control). Macrophage activity was, however, stimulated to 131% when the mice were immunized with giardia antigen prior to experimental infection. Giardia extract proved cytotoxic at a dose of 0.7 mg, to HeLa cells in tissue culture. These in vitro studies offer experimental evidence of the cytotoxic and immuno-toxic behaviour of G. lamblia towards the host cells.