Microbiological Diagnosis of Pulmonary Tuberculosis in Children: Comparative Study of Induced Sputum and Gastric Lavage

Abstract

Even under ideal circumstances, isolation rates of Mycobacterium Tuberculosis (M.Tb) from gastric lavage range from 28% to 40% in children with suspected pulmonary tuberculosis, although rates can rise to 75% in infants [1]. One year prospective study was undertaken in SMGS Hospital, Jammu to compare Induced Sputum (IS) with Gastric lavage (GL) for yield of M.Tb in children with suspected pulmonary tuberculosis.Children aged 6 months to 18 years admitted for chronic cough (more than 28 days) who could not expectorate and had one of the following: household contact (within past 2 years); failure to gain or loss of weight (in 3 months); Positive mantoux test (>10 mm); Chest radiography with pleural effusion, lymphadenopathy or nonresolving consolidation, were included in the study.Sixty-five children were initially included. Sixty children in whom successful sputum induction (SI) was possible took part in the study. They underwent GL and SI on three consecutive days according to a standard protocol [2].Children underwent morning GL after an overnight fast of at least 4 h. Gastric aspirate was immediately placed in a tube containing sodium carbonate. SI was undertaken after 2-3 h fast about 6 h after GL. Sputum was obtained by suctioning through nasopharynx after chest percussion.Samples were subjected to decontamination (Petroff's method) and centrifugation. Treated specimens were inoculated simultaneously on Lowenstein Jenson (LJ) medium and in Middlebrook 7 H9 media (MB7H9). Mycobacterial presence was confirmed by Acid Fast Bacilli (AFB) on direct smears or culture media. Classification as M.Tb was made by typicality of colony morphology and a positive niacin test.The median age of children was 4 years. Samples from IS to GL were positive in 8 (13%) and 5 (8%) children, respectively. The difference between yields for M.Tb from AFB smears to cultures on IS and GL was statistically insignificant (p=0.99) using the χ 2 test. Zar HJ, et al. noted that SI was more sensitive than GL, detecting almost twice the number of children with pulmonary tuberculosis [3].

Intensified specimen collection to improve tuberculosis diagnosis in children from Rural South Africa, an observational study

“…In recent years, less invasive methods of collecting respiratory tract specimens, including sputum induction and nasopharyngeal aspiration, have been evaluated in the context of research settings [5,16]. Results suggest at least equivalent yield from induced sputa [17,18] and nasopharyngeal aspirates [19] compared to gastric aspirates. Among pediatric inpatients from a tertiary center in Cape Town, South Africa, the culture yield from a single induced sputum specimen was equivalent to three consecutive gastric aspirates [5].…”

Alternative sputum collection methods for diagnosis of childhood intrathoracic tuberculosis: a systematic literature review

“…Out of 440 records screened, 30 studies (31 articles)5–35 were included in the review (online Supplementary figure 1).…”

Diagnosis of paediatric tuberculosis using sputum induction in Botswana: programme description and findings

“…11–14 Hatherill et al compared the diagnostic yield of TB from sputum induction and gastric lavage among children in an out-patient community setting, where the crude diagnostic yield for sputum induction was 5.8% compared to 6.2% for gastric lavage. 21 A Ugandan in-patient study of sputum induction yielded 12% positive smears and 30% positive cultures for M. tuberculosis .…”

“…12 In comparison, our sputum induction yield of 6% was comparable to those of community-based studies, 21 and lower than in studies focusing on hospitalised children. 11–14 …”

“…10 University-affiliated hospitals in Cape Town, South Africa, and Kampala, Uganda, have achieved culture positivity rates of up to 30%. 11–14 Although a successful paediatric sputum induction programme at a primary facility in the Western Cape was recently reported, 15 we are unaware of published paediatric sputum induction data from smaller facilities, or from African settings other than South Africa. We report the results of a programme that introduced paediatric sputum induction to Botswana’s public hospitals in Gaborone, Francistown, Serowe and Maun.…”