Tantawarak N.Lapphra K.Vanprapar N.Wittawatmongkol O.Phongsamart W.Rungmaitree S.Lertamornkitti N.Limpitikul W.Chokephaibulkit K.Mahidol University2026-04-182026-04-182026-05-01Pediatric Infectious Disease Journal Vol.45 No.5 (2026) , 386-392https://repository.li.mahidol.ac.th/handle/123456789/116250BACKGROUND: Diagnosing pediatric pulmonary tuberculosis (PTB) remains challenging due to low bacterial load and difficulty obtaining specimens. Current guidelines recommend 3-day acid-fast bacilli (AFB) and culture, with 1 molecular testing. We aimed to compare diagnostic yield across 1-, 2- and 3-day collection protocols. METHODS: We conducted a retrospective study of children <18 years with PTB at a tertiary hospital (2015-2023) who submitted 3 gastric aspirates (GA) or sputum specimens. Patients without molecular results, treated >14 days, or non-tuberculous mycobacterial infections were excluded. Diagnostic sensitivity was calculated using the World Health Organization-defined Clinical Reference Standard as the reference comparator. Two diagnostic approaches were assessed: (1) AFB + nucleic acid amplification test (NAAT); (2) AFB + NAAT + culture. RESULTS: Of 244 children screened, 165 were included (112 GA, 53 sputum). Mean ages were 4.8 and 14.5 years, respectively. In GA, (1) AFB + NAAT showed an absolute increase of 5.4% (95% confidence interval: -5.5 to 16.2) from days 1 to 2 (cumulative yield: 25.0%) and 2.7% (-8.9 to 14.2) on day 3 (27.7%). (2) Adding culture improved yield by 3.6% (-9.2 to 16.4) on day 2 (42.0%) and 2.7% (-10.3 to 15.7) on day 3 (44.6%). In sputum, (1) AFB + NAAT showed a 1.9% (-16.8 to 20.6) increase on day 3 (from 58.5% to 60.4%). (2) With culture, yielded consistently 73.6% across all days (0%, -16.8 to 16.8). CONCLUSIONS: Two-day specimen collection may be sufficient for PTB diagnosis. At least 1 culture should be included in the workup due to the highest sensitivity and ability to provide drug susceptibility information.MedicineArticleSCOPUS10.1097/INF.00000000000050682-s2.0-1050355246041532098741320828