{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T14:57:13Z","timestamp":1790866633765,"version":"4.1.0"},"reference-count":31,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pediatr."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Differentiating pulmonary tuberculosis (PTB) from community-acquired pneumonia (CAP) in children remains a significant diagnostic challenge. This study aimed to evaluate the diagnostic value of serum S100A8\/A9 in pediatric populations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      This multicenter prospective study enrolled 1,629 children aged 0\u223c\u2264 18 years with definitive diagnostic classifications, including a discovery cohort (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u20091,092) and a validation cohort (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u2009537). Participants were stratified into three groups: PTB (Confirmed, Unconfirmed), CAP (Viral, Bacterial,\n                      <jats:italic>Mycoplasma pneumoniae<\/jats:italic>\n                      , Mixed), and healthy controls (HC). Serum S100A8\/A9 levels were quantified by enzyme-linked immunosorbent assay, and diagnostic performance was assessed using ROC analysis.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      In both cohorts, S100A8\/A9 levels were markedly lower in PTB than in CAP but higher than in healthy controls. (both\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&amp;lt;\u20090.001). For distinguishing PTB from CAP, S100A8\/A9 achieved AUC values of 0.916 (95% CI: 0.895-0.937, sensitivity 87.1%, specificity 81.8%) in the discovery cohort and 0.932 (95% CI: 0.906\u20130.958, sensitivity 87.5%, specificity 86.4%) in the validation cohort. Compared with all CAP etiological subgroups, PTB children had the lowest S100A8\/A9 levels, with the highest AUC of 0.954 for PTB vs.\n                      <jats:italic>Mycoplasma pneumoniae<\/jats:italic>\n                      CAP. Age-stratified analysis revealed excellent discriminatory performance in children aged 5-18 years (AUC\u2009=\u20090.955 for PTB versus overall CAP). but impaired in children under 5 years (AUC\u2009=\u20090.838 for PTB versus overall CAP), with lower sensitivity (57.4%) for discriminating PTB from Viral-CAP. Furthermore, a concentration-dependent distribution was observed, with higher S100A8\/A9 levels associated with a decreasing proportion of PTB and an increasing proportion of CAP. In children aged 5\u201318 years, levels &amp;lt; 1,000\u2005ng\/mL were predominantly PTB (92.1%), and levels &amp;gt; 1,900 ng\/mL were highly predictive of CAP (96.8%).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Serum S100A8\/A9 is a promising potential biomarker for distinguishing pediatric PTB from CAP, characterized by age-related distribution and concentration-dependent diagnostic pattern.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fped.2026.1910674","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T14:20:15Z","timestamp":1790864415000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["S100A8\/A9 as a biomarker for differentiating pulmonary tuberculosis from community-acquired pneumonia in children: a multicenter cohort 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China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Tan","sequence":"additional","affiliation":[{"name":"Kunming Children\u2019s Hospital, Kunming Medical University","place":["Kunming, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meifen","family":"Wang","sequence":"additional","affiliation":[{"name":"Kunming Children\u2019s Hospital, Kunming Medical University","place":["Kunming, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Liu","sequence":"additional","affiliation":[{"name":"West China Second Hospital, Sichuan University","place":["Chengdu, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Zhu","sequence":"additional","affiliation":[{"name":"West China Second Hospital, Sichuan University","place":["Chengdu, 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