Infection and Drug Resistance (Jan 2022)
Effect of Mixed Infections with Mycobacterium tuberculosis and Nontuberculous Mycobacteria on Diagnosis of Multidrug-Resistant Tuberculosis: A Retrospective Multicentre Study in China
Abstract
Mingxiang Huang,1,* Yaoju Tan,2,* Xuxia Zhang,3,* Yufeng Wang,3 Biyi Su,2 Zhongtan Xue,3 Jingping Wang,4 Yu Pang3 1Department of Clinical Laboratory, Fuzhou Pulmonary Hospital and Fujian Medical University Clinical Teaching Hospital, Fuzhou, People’s Republic of China; 2Department of Clinical Laboratory, Guangzhou Chest Hospital, State Key Laboratory of Respiratory Disease, Guangzhou, People’s Republic of China; 3Department of Bacteriology and Immunology, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis & Thoracic Tumor Research Institute, Beijing, People’s Republic of China; 4Clinical Department, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis & Thoracic Tumor Research Institute, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yu PangDepartment of Bacteriology and Immunology, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis & Thoracic Tumor Research Institute, No. 9, Beiguan Street, Tongzhou District, Beijing, 101149, People’s Republic of China, Tel/Fax +86-10-8950 9359, Email [email protected] WangClinical Department, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis & Thoracic Tumor Research Institute, No. 9, Beiguan Street, Tongzhou District, Beijing, 101149, People’s Republic of China, Tel/Fax +86-10-8950 9029, Email [email protected]: Correct species identification is essential before initiation of TB treatment, due to substantial drug susceptibility profile differences among mycobacterial species. Given that nontuberculous mycobacteria (NTM) are frequently resistant to first-line anti-tuberculosis drugs, cases with mixed infections with Mycobacterium tuberculosis (MTB) and NTM tend to be diagnosed as multidrug-resistant tuberculosis (MDR-TB) cases. Here we report results of a retrospective multicentre study that was conducted to determine the prevalence of TB-NTM infections in previously diagnosed laboratory-confirmed multidrug-resistant tuberculosis (MDR-TB) patients using phenotypic drug susceptibility testing. The results were then used to identify risk factors associated with susceptibility to mixed infections.Methods: From January 2019 through December 2019, we retrospectively collected MDR-TB isolates from three TB specialised hospitals. Species identifications of isolates were performed using the MeltPro Myco assay.Results: A total of 837 MDR-TB isolates were analysed, of which 22 isolates (2.6%) were found to contain a mixture of NTM and MTB organisms. Significant differences in prevalence rates of mixed infections across regions were observed, with prevalence rates ranging from 0.0% (0/213) in Beijing to 3.4% (12/353) in Fuzhou to 3.7% (10/271) in Guangzhou. Among the 22 patients with NTM-TB mixed infections, a total of five different mycobacterial species were identified, of which the most prevalent species was Mycobacterium intracellulare. Notably, a history of previous TB episodes correlated with higher mixed infection risk.Conclusion: The results reported here demonstrated that mixed infections with MTB and NTM occurred in approximately 3% of suspected MDR-TB patients in China. These findings raise concerns about the accuracy of molecular diagnostics-based species identification tests and draw attention to the possibility that NTM-MTB mixed infections will be misdiagnosed as MDR-TB in high TB burden settings.Keywords: tuberculosis, nontuberculous mycobacteria, multidrug-resistant, China
