Efflux pump Rv1258c activates novel functions of the oxidative stress and via the VII secretion system ESX-3-mediated iron metabolic pathway in Mycobacterium tuberculosis

Risk factors for rifampicin-susceptible and isoniazid-resistant tuberculosis in adult patients with type 2 diabetes mellitus in Nanjing

OBJECTIVE

Globally, Tuberculosis(TB) with type 2 diabetes mellitus (T2DM) is becoming increasingly serious, especially the emergence of rifampicin-susceptible and isoniazid-resistant tuberculosis (Hr-TB), which increases the difficulty of treatment and the burden of disease. Therefore, this single-center retrospective cohort study analyzed risk factors of Hr-TB in adult patients with T2DM and pulmonary tuberculosis (PTB) in Nanjing to guide clinical practice and improve the long-term prognosis of patients.

METHODS

The clinical data of 279 adult inpatients diagnosed with culture-positive PTB and T2DM in the Second Hospital of Nanjing from January 2019 and December 2021 were collected. According to the drug susceptibility testing (DST) results, 44 patients with Hr-TB were categorized as the Hr-TB group, while the remaining 235 patients with drug-susceptible tuberculosis (DS-TB) were classified as DS-TB group. Hierarchical logistic regression was employed for multivariate analysis to identify variables associated with Hr-TB in patients with T2DM.

RESULTS

There were no significant differences in age, sex, body mass index (BMI), smoking, drinking, ethnicity, education level, or comorbidities between the DS-TB and Hr-TB groups. Multivariate logistic regression analysis revealed that, history of previous tuberculosis treatment (OR = 2.348, 95%CI: 1.025 ~ 5.379, P = 0.044), poor FPG control (OR = 2.402, 95%CI: 1.208 ~ 4.776, P = 0.012), and serum iron levels ≥ 14.3µmol/l (OR = 2.808, 95%CI: 1.334 ~ 5.910, P = 0.007) are independent risk factors for Hr-TB in adult patients with T2DM in Nanjing. Within the cohort, 241 patients were Newly treatment tuberculosis patients, and among them, poor FPG control (OR = 2.296, 95%CI: 1.073 ~ 4.915, P = 0.032), and serum iron levels ≥ 14.3µmol/l (OR = 2.418, 95%CI: 1.048 ~ 5.577, P = 0.038) were identified as risk factors for Hr-TB.

CONCLUSION

Poor fasting glycemic control and serum iron levels ≥ 14.3µmol/L are independent risk factors for the development of Hr-TB in adults with T2DM and PTB, moreover, the contribution of these as risk factors were more pronounced in the newly treatment tuberculosis patients subgroup than patients with a history of previous tuberculosis treatment. History of previous tuberculosis treatment was also found to be a risk factor for Hr-TB in adults with T2DM.

The efflux pumps Rv1877 and Rv0191 play differential roles in the protection of Mycobacterium tuberculosis against chemical stress

Background

It was previously shown that GlnA3sc enabled Streptomyces coelicolor to survive in excess polyamines. However, subsequent studies revealed that Rv1878, the corresponding Mycobacterium tuberculosis (M.tb) ortholog, was not essential for the detoxification of spermine (Spm), in M.tb. On the other hand, the multi-drug efflux pump Rv1877 was previously shown to enable export of a wide range of compounds, while Rv0191 was shown to be more specific to chloramphenicol.

Rationale

Therefore, we first wanted to determine if detoxification of Spm by efflux can be achieved by any efflux pump, or if that was dependent upon the function of the pump. Next, since Rv1878 was found not to be essential for the detoxification of Spm, we sought to follow-up on the investigation of the physiological role of Rv1878 along with Rv1877 and Rv0191.

Approach

To evaluate the specificity of efflux pumps in the mycobacterial tolerance to Spm, we generated unmarked ∆rv1877 and ∆rv0191 M.tb mutants and evaluated their susceptibility to Spm. To follow up on the investigation of any other physiological roles they may have, we characterized them along with the ∆rv1878 M.tb mutant.

Results

The ∆rv1877 mutant was sensitive to Spm stress, while the ∆rv0191 mutant was not. On the other hand, the ∆rv1878 mutant grew better than the wild-type during iron starvation yet was sensitive to cell wall stress. The proteins Rv1877 and Rv1878 seemed to play physiological roles during hypoxia and acidic stress. Lastly, the ∆rv0191 mutant was the only mutant that was sensitive to oxidative stress.

Conclusion

The multidrug MFS-type efflux pump Rv1877 is required for Spm detoxification, as opposed to Rv0191 which seems to play a more specific role. Moreover, Rv1878 seems to play a role in the regulation of iron homeostasis and the reconstitution of the cell wall of M.tb. On the other hand, the sensitivity of the ∆rv0191 mutant to oxidative stress, suggests that Rv0191 may be responsible for the transport of low molecular weight thiols.