Al-Moamary M S, Black W, Bessuille E, Elwood R K, Vedal S
Department of Medicine, Vancouver Hospital & Health Sciences Centre, University of British Columbia, Canada.
Chest. 1999 Sep;116(3):726-31. doi: 10.1378/chest.116.3.726.
Identification of acid-fast bacilli (AFB) in the sputum smear at the completion of tuberculosis therapy is in some settings considered evidence of treatment failure. However, some patients with pulmonary tuberculosis (TB) will have positive smear results with negative sputum culture results at the end of therapy. The objectives of this study were to estimate the prevalence of persisting positive sputum smear results in patients with TB and to identify characteristics that distinguish patients with persistently positive sputum smear results who also had negative sputum culture results from patients identified as treatment failures.
A population-based, historical cohort study with nested case control study.
British Columbia Division of Tuberculosis Control central case registry.
All 428 patients with culture-proven pulmonary TB in British Columbia over 7 years with sputum that was positive for AFB.
Review of laboratory data of all 428 patients, as well as clinical data of a subset of 30 patients with persistently positive smear results beyond 20 weeks.
Sputum smears were positive for AFB in 205 patients (48%) at 4 weeks, in 30 patients (7%) at 20 weeks, and in 12 patients (3%) at 36 weeks. Of the patients with smear results that were persistently positive at 20 weeks, 23 (77%) had negative sputum culture results and 7 (23%) had positive sputum culture results (ie, they were treatment failures). Patients identified as treatment failures had more localized disease as shown on chest radiographs, had less radiographic improvement at follow-up, had a higher prevalence of drug resistance, and were less compliant with medications than patients with persistently positive smear results and negative culture results. No subject with a negative culture result relapsed over the 6- to 48-month observation period.
Sputum that is persistently positive for AFB in patients in developed countries is more likely to be associated with negative culture results than with treatment failure.
在某些情况下，结核病治疗结束时痰涂片抗酸杆菌（AFB）检测呈阳性被视为治疗失败的证据。然而，一些肺结核（TB）患者在治疗结束时痰涂片结果为阳性而痰培养结果为阴性。本研究的目的是估计肺结核患者痰涂片持续阳性的患病率，并确定区分痰涂片持续阳性且痰培养结果为阴性的患者与被认定为治疗失败患者的特征。
一项基于人群的历史性队列研究，并嵌套病例对照研究。
不列颠哥伦比亚省结核病控制部门中央病例登记处。
不列颠哥伦比亚省7年间所有428例经培养证实为肺结核且痰AFB检测呈阳性的患者。
回顾所有428例患者的实验室数据，以及30例痰涂片持续阳性超过20周患者的子集的临床数据。
4周时205例患者（48%）痰涂片AFB检测呈阳性，20周时30例患者（7%）呈阳性，36周时12例患者（3%）呈阳性。在20周时痰涂片结果持续阳性的患者中，23例（77%）痰培养结果为阴性，7例（23%）痰培养结果为阳性（即他们是治疗失败患者）。与痰涂片持续阳性且培养结果为阴性的患者相比，被认定为治疗失败的患者胸部X光片显示病变更局限，随访时影像学改善较少，耐药率更高，且服药依从性较差。在6至48个月的观察期内，培养结果为阴性的患者均未复发。
在发达国家，患者痰涂片AFB持续阳性更可能与培养结果阴性相关，而非治疗失败。
