270 research outputs found
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
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
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)
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
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
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