ABSTRACT
@#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
The presence of tRNA array, a region with high tRNA gene number and density, has been demonstrated in Mycobacterium genus. However, a recent phylogenomic study revealed the existence of five distinct monophyletic groups (genera) within this genus. Considering this new scenario, and based on in-silico analyses, we have identified and characterised the abundance and diversity of tRNA array units within Mycobacterium, Mycolicibacterium gen. nov., Mycolicibacillus gen. nov., and Mycobacteroides gen. nov. The occurrence and prevalence of tRNA arrays among the genera belonging to Actinobacteria indicate their possible role in the organismal fitness.