Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, China.
Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China.
Front Public Health. 2023 Feb 10;11:1064512. doi: 10.3389/fpubh.2023.1064512. eCollection 2023.
The objective of the study was to identify the causes of smear-positive-culture-negative (S+/C-) outcomes of patients with tuberculosis during the treatment course.
A laboratory-based retrospective study was performed at the Beijing Chest Hospital in China. Within the study period, all patients with pulmonary tuberculosis (PTB) who undertook anti-TB treatments and yielded smear positive outcomes with simultaneous culture outcomes on sputa were considered. Patients were classified into three groups: (I) performed LJ medium culture only; (II) performed BACTEC MGIT960 liquid culture only; and (III) performed both LJ culture and MGIT960 culture. The S+/C- rates of each group were analyzed. The clinical medical records regarding patient category, follow-up bacteriologic examination data, and treatment response were investigated.
In total, 1,200 eligible patients were enrolled, and the overall S+/C- rate was 17.5% (210/1,200). Group I had obviously higher S+/C- rate (37%) than group II (18.5%) and group III (9.5%). When solid and liquid cultures were considered independently, the S+/C- outcome was observed more frequently in the solid culture group than in the liquid culture group (30.4%, 345/1,135 vs. 11.5%, 100/873; < 0.001, χ = 102.64). Among the 102 S+/C- patients who had follow-up cultures performed, 35 (34.3%) had positive culture outcomes. Whereas among the 67 patients with follow-up information for more than 3 months but without supportive bacteriological evidence, 45 (67.2%, 45/67) had unfavorable prognosis (including relapse and unimproved conditions), and only 22 (32.8%, 22/67) patients had improved conditions. Compared with new cases, retreated cases produced S+/C- outcomes more frequently and had more chances to be cultivated bacilli successfully afterward.
Among our patients, the sporadic smear positive and culture negative outcomes for sputa are more likely associated with the technical failures of culture than with dead bacilli, and this is especially noteworthy for LJ medium culture.
本研究旨在明确治疗过程中涂阳培养阴性（S+/C-）患者的病因。
本研究为中国北京胸科医院的一项基于实验室的回顾性研究。在此研究期间，所有接受抗结核治疗且痰涂片阳性且培养阳性的肺结核（PTB）患者均被纳入研究。患者分为三组：（I）仅行 LJ 培养基培养；（II）仅行 BACTEC MGIT960 液体培养；和（III）同时行 LJ 培养和 MGIT960 培养。分析每组的 S+/C-率。研究调查了患者分类、随访细菌学检查数据和治疗反应的临床病历。
共纳入 1200 例合格患者，总 S+/C-率为 17.5%（210/1200）。组 I 的 S+/C-率（37%）明显高于组 II（18.5%）和组 III（9.5%）。当同时考虑固体和液体培养时，固体培养组的 S+/C-结果比液体培养组更常见（30.4%，345/1135 比 11.5%，100/873；<0.001，χ=102.64）。在 102 例进行了后续培养的 S+/C-患者中，35 例（34.3%）培养结果阳性。而在 67 例有超过 3 个月随访信息但无支持性细菌学证据的患者中，45 例（67.2%，45/67）预后不良（包括复发和病情无改善），仅有 22 例（32.8%，22/67）病情改善。与新发病例相比，复发病例更易出现 S+/C-结果，且后续培养出细菌的可能性更高。
在我们的患者中，痰涂片阳性而培养阴性的偶发结果更可能与培养技术失败有关，而不是与死菌有关，这在 LJ 培养基培养中尤其值得注意。
