Laboratory diagnosis of childhood tuberculosis (Editorial)

Tuberculosis in childhood occurs with different manifestations. All these forms of tuberculosis, except when cavitation occurs in pulmonary tuberculosis, are paucibacillary in nature. For this reason, even though at the present time bacteriological confirmation is still the final proof of tuberculous disease, it is difficult to obtain. Depending on the form of disease manifestation, several specimens like sputum and/or gastric lavage, as children are often unable to produce sputum, lymphnodes and other biopsy specimens, pus, ascitic fluid, pleural or cerebrospinal fluid (CSF) need to be collected. If delay is anticipated, biopsy specimens may be collected in suitable transport medium for sending it to laboratory

Rapid methods for culture of mycobacteria

Tuberculosis remains a major health problem in many parts of the world. Rapid and accurate detection of M. Tuberculosis is essential not only to speed up the treatment of patients but also to control the disease in the population. Bacteriological investigations play a key role in the diagnosis of different forms of tuberculosis

Two speedier phenotypic methods on drug susceptibility testing of Mycobacterium tuberculosis

The introduction of drugs beginning with streptomycin for the treatment of tuberculosis (TB) and the subsequent emergence of drug resistant Mycobacterium tuberculosis strains has made the testing for susceptibility of the latter a basic necessity. The World Health Organization (WHO) recognized the importance of these laboratory issues even in the early sixties and conducted extensive studies by involving laboratories from both disease endemic developing countries (DEDCs) and disease non endemic countries to standardize the susceptibility (DEDCs) testing procedures for M. tuberculosis for all the three methods that were in vogue, viz., absolute concentration method, resistance ratio method (RR) and the proportion susceptibility testing method (PST)

Quality control in isolation and identification of mycobacteria from clinical specimens

The importance of laboratory test results in the practice of medicine and the increasing complexity of many modern laboratory procedures makes it essential that quality control (QC) measures be instituted to monitor the rapidly expanding, often automated, laboratory technology. QC is the responsibility of all laboratory personnel. QC procedures should be performed on a regular basis in the Mycobacteriology laboratory to assure reproducibility and reliability of laboratory results. For a QC to be helpful, it must be practicable and workable. Most of the clinical laboratories in the developing countries lack a well organised QC network. On the contrary, the majority of the clinical laboratories in the USA are under the jurisdiction of one or more accreditation agencies

Study on environmental mycobacteria obtained from South Indian BCG trial area

Non Tuberculous Mycobacteria (NTM) are widely distributed in our environment and man is being constantly exposed to these organisms by various means(l). This immunologically important contact may be involved in the modulation of immunity to tuberculosis. Prior sensitization with NTM has beep considered as one of the explanations for the failure of BCG to provide protection against tuberculosis in the South Indian trial. Tuberculosis surveys using PPD-B have shown that in this area, prevalence of sensitization reaches 90%. in persons by age 14(2). Identification of NTM isolates from sputum samples in this area has shown M.avium-intracellulare and M.scrofulaceum to be among the important species(3). However. the actual distribution profile of the various NTM species in the environment of this area is not known

Molecular methods in the diagnosis of tuberculosis

Editoria

Tuberculosis: Epidemiology and Diagnosis

Despite the discovery of the tubercle bacillus more than a hundred years ago, and all the advances in our knowledge of the disease since then, tuberculosis still remains one of the major health problems facing mankind, particularly in developing countries. About one third of the World’s population is infected with M. tuberculosis. It is estimated that currently there are about 9 million new cases of tuberculosis with 3 million deaths worldwide. More people die of tuberculosis than any other infectious disease. Death from tuberculosis comprises 25% of all avoidable deaths in developing countries. Ninety five per cent of tuberculosis cases and 98% of tuberculosis deaths are in developing countries and 75% of tuberculosis cases are in the economically productive age group1. Geographically, the regions with the highest prevalence and infection rates are the eastern fringe of Asia, the Indian subcontinent, the South eastern part of Africa, South-east Europe, Central America and the Western part of the South America. The WHO has declared a global emergency in 1993 with respect to reemerging menace of tuberculosis

Newer antimycobacterial drugs and their role in the treatment of tuberculosis patients

The main lesion in pulmonary tuberculosis, the pulmonary cavity, contains a large number of mycobacteria (about 108 colony forming units). Of these, a large bacillary population is located in the thin liquid caseous layer that covers the inner part of the cavitary wall. Here, the bacilli are extracellular which multiply actively because of the availability of oxygen and nutritive substances. There are at least 2 other bacillary populations, one inside macrophages and another inside solid caseous foci; both these populations are limited in size because environmental conditions are unfavourable for their growth.1 Among the organisms in these 3 populations, which are normally drug sensitive, drug resistant mutants develop at a mean frequency of about 10-6

Newer Methods For The Diagnosis of Childhood Tuberculosis

For an infectious disease like tuberculosis, which is transmitted by aerosol droplets, the rapid and accurate detection of M.tuberculosis is essential, not only to speed up the treatment of the patient but also to control the spread of the disease. Tuberculosis in childhood occurs with different manifestations. All these forms of tuberculosis, except when cavitation occurs in pulmonary tuberculosis, are paucibacillary in nature. For this reason, even though at the present time bacteriological confirmation is still the final proof of tuberculous disease, it is difficult to obtain. Depending on the form of disease manifestation, several specimens like sputum and/or gastric lavage, as children are often unable to produce sputum, lymph nodes and other biopsy specimens, pus, ascitic fluid, pleural or cerebrospinal fluid (CSF) need to be collected. If delay is anticipated, relevant specimens may be collected in suitable transport medium for sending it to the laboratory. There are two ways to address diagnosis of tuberculosis. The direct approach is concerned with the detection of the bacteria by microscopy or culture, detection of tuberculostearic acid (bacterial wall component), detection and identification of mycobacterial antigen by the use of polyclonal or monoclonal antibodies, analysis of lipid composition by chromatography, and the detection of DNA or RNA of mycobacterial origin by hybridization with a DNA probe with or without amplification of nucleic acids. The indirect approach relates to measurement of host immune response against the mycobacteria. This includes humoral immunity via the detection of antibodies against the bacteria and cellular response via skin tests

An overview on drug resistant tuberculosis in India

Tuberculosis remains one of the major public health problems in India. It has been estimated that about 30% of the world’s tuberculosis patients are residing in India1. Since the control measures for tuberculosis such as BCG vaccination and chemoprophylaxis seem to be unsatisfactory, treatment with anti-tuberculosis drugs becomes inevitable. In recent years, the treatment of tuberculosis has been threatened by the increasing number of patients with drug resistant tuberculosis. Although the phenomenon of drug resistance to Mycobacterium tuberculosis was observed even in the early days of streptomycin usage, the current threat is due to the emergence of strains resistant to the potent bactericidal anti-tuberculosis drugs such as isoniazid and rifampicin which are used in the tuberculosis control programmes