Secondary bacterial flora in patients with pulmonary tuberculosis - a preliminary report

Sputum samples from 100 smear positive or skiagram positive pulmonary tuberculosis patients were cultured for superinfecting or co-injecting bacteria. These patients were equally divided into five groups. This included Croup-I who are not treated; Group-II who are treated up to three months; Group-III who are treated for more than three but less than six months; Group-IV treated more than six months and lastly Group-V who have completed the prescribed treatment schedule of varying durations. Neisseria catarrhalis and Strep. viridans predominated in all patients irrespective of group, other organisms isolated, were Micrococci, E.Coli, Serratia, Proteus and Pseudomonas. There was no significant difference in the pattern of organisms isolated from different group of patients. The antibiogram showed the usual susceptibility pattern

Large-Restriction-Fragment Polymorphism Analysis of Mycobacterium chelonae and Mycobacterium terrae Isolates

Mycobacterium chelonae and Mycobacterium terrae were reported to be frequently present in the environment of the Mycobacterium bovis BCG trial area in south India. Six isolates of M. chelonae and four isolates of M. terrae obtained from different sources in this area were analyzed by pulsed-field gel electrophoresis (PFGE) to examine large-restriction-fragment (LRF) polymorphism using the chromosomal DNA digested with DraI and XbaI restriction enzymes. With the exception of one isolate of M. terrae, DNA from all other isolates could be digested with DraI and XbaI and resulted in separable fragments. Visual comparison of the LRFs showed a unique pattern for each of the isolates tested. A computer-assisted dendrogram of the percent similarity demonstrated a high degree of genetic diversity in this group of isolates. This study demonstrates that species of nontuberculous mycobacteria, particularly M. chelonae and M. terrae, can be successfully typed by their LRF pattern using PFGE, which does not require species-specific DNA probes

Intraspecies differentiation of strains of Mycobacterium tuberculosis obtained from Czechoslovakian, Mongolian and South Indian patients

Twenty nine strains of M. tuberculosis from Czechoslovakia, 46 from Mongolia and 50 from South India were tested for virulence in the guineapig, sensitivity to thiophen-2-carboxylic acid hydrazide (TCH) and phage type. Most of the Czechoslovakian and Mongolian strains (93 and 80% respectively) were highly virulent in the guineapig while only 36 per cent of the South Indian strains showed high virulence. Similarly very high proportions of Czechoslovakian (97%) and Mongolian strains (85%) were resistant to TCH as against only 22 per cent of South Indian strains. The phage type I was observed in none of the Czechoslovakian strains, 4 per cent of Mongolian strains and in 68 per cent of South Indian strains. Thus, the Czechoslovakian and Mongolian strains, in general, resembled the classical M. tuberculosis, while the South Indian strains were generally of low virulence, susceptible to TCH and of phage type I. Evidence accumulated over the last two decades has shown that there exist within the species Mycobacterium tuberculosis, some variants and types on a subspecies level. The most prominent of these, the South Indian variant of M. tuberculosis, is distinguished by a number of characteristic features viz., lower virulence in the guineapig, enhanced susceptibility to hydrogen peroxide and thiopen-2-carboxylic acid hydrazide (TCH), natural resistance to thioacetazone and p-amino salicylic acid, clustering into an intermediate phage type I and characteristic composition of cell wall lipids1-5. Howeve

Transportation of lymph node biopsy specimens in selective Kirchner’s liquid medium for culture of tubercle bacilli

Lymph node biopsy specimens, obtained from 297 paediatric and adult patients with tuberculous lymphadenitis at Madurai, were transported in selective Kirchner’s liquid medium (KL-T) to the Tuberculosis Research Centre, Madras and processed for culture. Mycobucterium tuberculosis was isolated from 201 (68%) specimens. Of the 192 specimens received within 4 days of resection, 134 (69.8%) yielded M. tuberculosis on culture and of the 105 specimens received after 5 days, 67 (63.8%) were culture positive; the difference was not statistically significant. By incubating KL-T alone further, after removing the gland for processing, it was found that mere contact with the excised node during transportation was enough to retrieve 77 (38.3%) of the total of 201 positive isolates obtained, the delay did not affect the culture positivity rate. Thus, lymph node specimens for culture of tubercle bacilli can be stored in the refrigerator for up to 15 days and transported in KL-T at ambient temperature for 18-20 h without any loss in culture positivity

Computerized Tomography Detects Pulmonary Lesions in Children with Normal Radiographs Diagnosed to have Tuberculosis

This report is based on observations during the conduct of a larger study to develop diagnostic criteria for childhood tuberculosis (TB). Of 20l children confirmed to have pulmonary or lymph node TB, 84 had normal chest radiographs. Computerized tomography (CT) of the chest was performed in nine of them, seven of whom had normal chest radiographs while two had visible calcification. Eight of the nine children had definitive lesions detected by computerized tomography of the chest. While five children had primarily hilar lymph node enlargement, three had pulmonary parenchymal lesions. The use of more sensitive diagnostic tests like computed tomography helps to detect tuberculosis lesions not otherwise visualized on chest radiographs. This report highlights the difficulty in excluding active tuberculosis in children. More studies are required on the role of CT scans in the diagnosis of tuberculosis in children

Survelliance of drug resistance in tuberculosis in the state of Tamil Nadu

Summary: Surveillance of drug resistance was carried out at State level to obtain data which are standardised and comparable using guidelines prescribed by the WHO/IUATLD Working Group on Anti-tuberculosis Drug Resistance Surveillance. Objective: To determine the proportion of initial and acquired drug resistance in cases of pulmonary tuberculosis in Tamilnadu, in order to use the level of drug resistance as a performance indicator of the National Tuberculosis Programme. Methods: Two specimens of sputum from each of a total of 713 patients attending 145 participating centres all over the state were tested by smear and culture examination and drug susceptibility tests of Isoniazid, Rifampicin, Ethambutol and Streptomycin. Results: Out of 400 patients for whom drug susceptibility results were available, 384 (96%) had no history of previous anti-tuberculosis treatment. Of these, 312 (81%) were susceptible to all the drugs tested. Resistance to isoniazid was seen in 15.4% of patients and to Rifampicin in 4.4% including resistance to Isoniazid and Rifampicin in 3.4%. Conclusion: There has been a gradual increase in initial drug resistance over the years in this part of the country

Evaluation of a Cold Staining Method for Acid-Fast Bacilli in Sputum

Comparison between the Ziehl-Neelscn staining method for acid-fast bacilli, applied with and without heating, was carried out in a controlled investigation using smears prepared from 306 sputum samples collected prior to treatment from suspected cases of pulmonary tuberculosis. Smear and culture positively were graded and the colour intensity of bacilli recorded. Results showed that the chance corrected agreement (Kappa) between Z-N and cold methods was only 78%. The sensitivity of the Z-N and cold methods were 84% and 77% respectively when compared with culture results. Assuming 10% smear positivity among symptomatics reporting to Peripheral Health Institutions (PHIs), the positive predictive value of the cold method was very low(53%). When compared to culture, the positive predictive value is 71% for the Z-N method and 57% for the cold method for a symptomatic population with 15% culture positivity. In the absence of heating. penetration of the stain was significantly reduced and consequently the number of bacilli detected was less. The inability to take the stain without heating was seen in smears from all grades of culture positive samples: thus even heavy positives were missed by the cold method. The evaluation of the cold method against the standard Z-N method highlights its limitations and demonstrates that it is not as reliable as the standard Z-N method

A direct rifampicin sensitivity test for tubercle bacilli

A direct sensitivity test for rifampicin has been standardised for early detection of resistance for the mycobacterium tuberculosis smear positive sputum samples. Indirect sensitivity tests set up from primary cultures of the same samples served as controls. The direct test showed 95 per cent agreement with the standard indirect test and as such 74 per cent and 90 per cent of the resistant strains were detected by the fourth week and fifth week, respectively, with an overall gain of 4-5 wks time. Resistance could be detected earlier for multibacillary specimens. This direct sensitivity test on Lowenstein Jensen (LJ) medium offers a feasible alternative for laboratories which lack facilities to perform drug susceptibility tests by the rapid but sophisticated and costly BACTEC method. The method is simple to perform, economic, reliable and amenable to confirmation by the indirect test, if needed

First Panel Testing In SAARC Regional Networks of TB Reference Laboratories

Setting: South Asian Association for Regional Co-operation (SAARC) region with disproportionately high burden of TB in comparison of regional population. Objective: To establish a quality assurance on sputum smear microcopy in SAARC regional network of TB reference laboratories. Methods: Panel of slides were prepared and sent to national TB reference laboratories. The laboratory technician read the slides and sent report to SAARC TB center and report were analyzed. Results: Seven laboratories had no error of any type and one laboratory got two minor types of errors. Conclusion: Mot of the laboratories had excellent performance in panel testing