Specimen collection methods in the diagnosis of childhood tuberculosis

Abstract

The importance and severity of the childhood tuberculosis frequently present with advanced disease. Automated liquid (TB) disease burden is recognized in many developing broth cultures such as MGIT and BACTEC offer slightly countries. Of the estimated 8.3 million new TB cases reported superior sensitivity and reduced turn around time compared to the World Health Organization (WHO) in 2000, 884 019 to the conventional solid media. However, their excessive cost were children. However, the diagnosis of childhood and requirement for laboratory infrastructure remains a major TB is complicated by the absence of a practical gold standard, limitation. Alternative, simple and rapid mechanisms for as bacteriologic confirmation is rarely achieved due to the detecting mycobacterial growth (e.g., colorimetric cultures) predominantly paucibacillary nature of childhood TB. Sputum have been developed, but require further validation in microscopy, often the only test available in endemic areas, is children. positive in less than 10-15% of children with probable TB and culture yields are usually low (30-40%). For this reason, in Collection of bacteriologic specimens is a major challenge non-endemic areas, use of a diagnostic triad is widely in the workup of a case of suspected pediatric TB. Table 1 advocated: 1) known contact with an adult index case (e.g., shows various methods that are used to collect bacteriologic household contact), 2) a positive tuberculin skin test (TST) specimens, their limitations and potential advantages. as evidence of M. tuberculosis infection and 3) suggestive Two to three fasting gastric aspirates collected on signs on the chest radiograph (CXR). However, accuracy of consecutive days and usually requiring hospital admission are this triad is greatly diminished in developing countries where routinely advised in children who cannot cough up sputum. the majority of the population acquire infection during A retrospective study from California compared the childhood and where transmission is not restricted to bacteriologi yield achieved in gastric aspirates collected from household contact with a known index case. Consequently, hospitalized and non-hospitalized children. Although the in endemic settings such as India where the discriminatory yield in hospitalized children was higher (percentage of value of known M. tuberculosis exposure and/or infection is positive cultures 48% vs 37%), this difference was not drastically reduced, the diagnosis of childhood TB depends statistically significant, which suggests that hospitalization mainly on clinical features and the subjective interpretation may not be a prerequisite for the collection of a good gastric of the CXR. In such settings, there is a definite need to aspirate specimen. improve bacteriologic diagnosis of childhood TB and overcome the limitations of predominantly clinical approaches. Bronchoalveolar lavage, using flexible fiberoptic bronschoscopy, has additive value when used in combination Although the bacteriologic yield in children is low, with gastric lavage, but this technique is highly specialized adolescent children frequently develop sputum smear-positive and is unavailable in most endemic areas. adult-type disease and sputum microscopy has definite Peru, mid-morning nasopharyngeal aspiration was compared diagnostic value in this subset of children. A recent study with early morning gastric aspiration; gastric aspiration demonstrated that the bacteriologic yield in children with TB provided a slightly better yield than nasopharyngeal aspiration (11%)