Abstract: Objective　To identify the species of Mycobacteroides abscessus complex (MABC) in patients with pulmonary infection from the Second Affiliated Hospital of Hainan Medical University, and to investigate the species types, drug sensitivity and population distribution of MABC in pulmonary infection in Hainan. Methods　Respiratory tract specimens were collected from suspected tuberculosis patients who visited the Second Affiliated Hospital of Hainan Medical University from January 2014 to December 2021 and cultured for Mycobacterium isolation. Non-tuberculous mycobacteria (NTM) strains were preliminarily identified by p-nitrobenzoic acid/thiophen-2-carbohydrazide (PNB/TCH) medium and DNA microarray chip, and then MABC and its subspecies were identified by hsp65 and rpoB gene sequencing. In vitro antimicrobial susceptibility test was performed by broth microdilution method. Results　A total of 3 025 respiratory specimens from suspected pulmonary tuberculosis patients were collected during the study period. Among the 123 patients with identified MABC isolates, 124 MABC strains were isolated and identified, including 74 strains of Mycobacteroides abscessus subsp. abscessus, 38 strains of Mycobacteroides abscessus subsp. massiliense and 12 strains of Mycobacteroides abscessus subsp. bolletii. Among them, 118 patients had single MABC subspecies infection, one patient had mixed infection with two MABC subspecies, two patients had mixed infection with MABC and other NTM, and two cases had mixed infection with MABC and M.tuberculosis. There were more female patients than male patients with a ratio of 1:0.64, and those aged 50 and above amounted to 76.42% (94/123, 95%CI: 67.93%-83.61%). There was no significant difference in age distribution between male and female patients (Z=-0.944, P=0.347). The drug susceptibility results showed that all MABC strains were sensitive to Tigecycline (TGC), with a resistance rate of 0.81% (1/124) to Amikacin (AK), and resistance rates of 6.45% (8/124), 32.26% (40/124), and 74.19% (92/124) to Cefoxitin (FOX), Linezolid (LZD), and Imipenem (IPM), respectively. For Clarithromycin (CLR), MABC showed induced resistance , and there was a statistically significant difference in the CLR (14D) resistance rates among the three subspecies (χ2=66.335, P<0.001). The resistance rates to Tobramycin (TOB), Doxycycline (DOX), Moxifloxacin (MFX), Ciprofoxacin (CIP), Trimethoprim/Sulfamethoxazole (TMP-SMX), and Amoxicillin/Clavulanic acid (AMC) were high, all >80%. Conclusion　 In Hainan Province, pulmonary infections with MABC are mainly caused by Mycobacteroides abscessus subsp. Abscessus, which show high rates of inducible resistance to CLR. Timely and accurate identification of MABC to subspecies and drug susceptibility testing are of significant important for clinical decision-making.

Abstract: Objective　To investigate the influencing factors related to the recent transmission of multidrug-resistant tuberculosis (MDR-TB) in Hainan Province, with the goal of providing an epidemiological basis for the region's prevention and control strategies, as well as clinical decision-making regarding MDR-TB. Methods Clinical respiratory specimens from MDR-TB patients treated at the Second Affiliated Hospital of Hainan Medical University from July 2019 to June 2021 were collected for mycobacterial isolation and cultivation. Isolates of multidrug-resistant Mycobacterium tuberculosis (MDR-MTB) identified through proportional drug-susceptibility screening were subjected to whole-genome sequencing (WGS). In conjunction with clinical and epidemiological data, factors influencing recent MDR-TB transmission were analyzed. Results A total of 202 MDR-TB patients were included in the study, primarily distributed across 18 cities and counties of Hainan Province (excluding Sansha City), and the patients were predominantly male. Phylogenetic analysis of the MDR-MTB strains showed that 56.4% (114/202) belonged to Lineage 2.2 (Beijing), 27.2% (55/202) to Lineage 2.1 (non-Beijing), 13.4% (27/202) to Lineage 4 (Euro-American), and 3.0% (6/202) to Lineage 1 (Indo-Oceanic). Through genetic distance analysis, 42 strains of MDR-MTB were found to be grouped into 15 clusters, with a clustering rate of 20.8%, indicating a significant level of recent transmission. Analysis of transmission-related factors revealed that non-agricultural occupations, initial treatment, and unmarried status were positively correlated with recent MDR-TB transmission, while older age and a history of smoking were negatively correlated. Notably, Lineage 2.2 (Beijing) showed a higher likelihood of MDR-TB transmission compared to Lineage 2.1 (non-eijing). Multivariate logistic regression analysis further identified that patients receiving initial treatment were an independent risk factor for recent MDR-TB transmission. Conclusions MDR-TB in Hainan Province exhibits distinctive genetic diversity, with Lineage 2.2 (Beijing) being the predominant epidemic strain. Recent transmission of MDR-TB in Hainan Province is associated with non-agricultural occupations, initial treatment, unmarried status, and Lineage 2.2 (Beijing), with the initial treatment being a likely independent risk factor for transmission. These findings offer vital clues for controlling MDR-TB and are expected to guide the formulation of targeted prevention and control strategies to reduce the transmission of the MDR-TB epidemic.