Department of Tuberculosis and Chest Medicine, Gulab Devi Hospital, Lahore, Pakistan.
Department of Microbiology, Gulab Devi Hospital, Lahore, Pakistan.
BMC Infect Dis. 2021 Apr 24;21(1):381. doi: 10.1186/s12879-021-06086-8.
There is scarce knowledge on the prevalence of diseases caused by non-tuberculous mycobacteria (NTM) in Pakistan. In the absence of culture and identification, acid-fast bacilli (AFB) causing NTM disease are liable to be misinterpreted as tuberculosis (TB). Introduction of nucleic acid amplification testing for Mycobacterium tuberculosis complex (MTBC) offers improved diagnostic accuracy, compared with smear microscopy, and also assists in differentiating MTBC from other mycobacteria. This study aimed to investigate the prevalence of NTM among patients investigated for TB and describe NTM disease and treatment outcomes at a tertiary care hospital in Pakistan.
This is a retrospective study, data on NTM isolates among culture-positive clinical samples over 4 years (2016-19) was retrieved from laboratory records. Information on clinical specimens processed, AFB smear results, and for the AFB positive isolates, results of species identification for MTBC, and for NTM isolates, results of species characterization and drug susceptibility testing was collected. Additional clinical data including patient characteristics, treatment regimens, and outcomes were collected for patients with NTM disease treated at Gulab Devi Hospital, Lahore.
During the study period, 12,561 clinical specimens were processed for mycobacterial culture and 3673 (29%) were reported positive for AFB. Among these 3482 (95%) were identified as MTBC and 191 (5%) as NTM. Among NTM, 169 (88%) were isolated from pulmonary and 22 (12%) from extrapulmonary specimens. Results of NTM speciation were available for 60 isolates and included 55% (n = 33) M. avium complex and 25% (n = 15) M. abscesses. Among these patients, complete clinical records were retrieved for 12 patients with pulmonary disease including nine infected with M. avium complex and three with M. abscessus. All 12 patients had a history of poor response to standard first-line anti-TB treatment. Ten patients were cured after 18 months of treatment, whereas, one with M. abscessus infection died and another was lost to follow up.
In TB endemic areas, NTM can be misdiagnosed as pulmonary TB leading to repeated failed anti-TB treatment and increased morbidity, emphasizing the need for improved diagnosis.
关于巴基斯坦非结核分枝杆菌（NTM）引起的疾病的流行情况，我们的了解还很少。在缺乏培养和鉴定的情况下，导致 NTM 疾病的抗酸杆菌（AFB）很容易被误诊为结核病（TB）。与显微镜检查相比，分枝杆菌复合群（MTBC）的核酸扩增检测的引入提供了更高的诊断准确性，并且还可以帮助区分 MTBC 和其他分枝杆菌。本研究旨在调查在巴基斯坦一家三级护理医院中，接受 TB 检查的患者中 NTM 的流行情况，并描述 NTM 疾病和治疗结果。
这是一项回顾性研究，从实验室记录中检索了 4 年（2016-19 年）期间培养阳性临床样本中 NTM 分离株的数据。收集了有关临床标本处理、AFB 涂片结果的信息，对于 AFB 阳性分离株，还收集了 MTBC 种属鉴定结果，以及对于 NTM 分离株，收集了种属特征和药敏试验结果。对于在拉合尔古利德维医院接受 NTM 疾病治疗的患者，还收集了其他临床数据，包括患者特征、治疗方案和结局。
在研究期间，共处理了 12561 份临床标本进行分枝杆菌培养，3673 份（29%）报告 AFB 阳性。其中 3482 份（95%）被鉴定为 MTBC，191 份（5%）为 NTM。在 NTM 中，169 份（88%）分离自肺部标本，22 份（12%）分离自肺外标本。60 份 NTM 种属分离株的结果可用，包括 55%（n=33）的鸟分枝杆菌复合群和 25%（n=15）的脓肿分枝杆菌。在这些患者中，共检索到 12 例肺部疾病患者的完整临床记录，其中 9 例感染了鸟分枝杆菌复合群，3 例感染了脓肿分枝杆菌。所有 12 例患者均有对标准一线抗 TB 治疗反应不佳的病史。10 例患者经过 18 个月的治疗后痊愈，而 1 例脓肿分枝杆菌感染者死亡，1 例失访。
在结核病流行地区，NTM 可能被误诊为肺结核，导致反复抗 TB 治疗失败和发病率增加，这强调了改进诊断的必要性。
