Noncanonical Mismatch Repair Protein NucS Modulates the Emergence of Antibiotic Resistance in Mycobacterium abscessus.

NucS/EndoMS-dependent noncanonical mismatch repair (MMR) ensures the stability of genomic DNA in mycobacteria and acts as a guardian of the genome by preventing the accumulation of point mutations. In order to address whether the inactivation of noncanonical MMR could increase the acquisition of drug resistance by mutation, a ΔnucS strain was constructed and explored in the emerging pathogen Mycobacterium abscessus. Deletion of nucS resulted in a mutator phenotype with increased acquisition of resistance to macrolides and aminoglycosides, the two main groups of antimycobacterial agents for M. abscessus treatment, and also to second-line drugs such as fluoroquinolones. Inactivation of the noncanonical MMR in M. abscessus led to increases of 10- to 22-fold in the appearance of spontaneous mutants resistant to the macrolide clarithromycin and the aminoglycosides amikacin, gentamicin, and apramycin, compared with the wild-type strain. Furthermore, emergence of fluoroquinolone (ciprofloxacin) resistance was detected in a nucS-deficient strain but not in a wild-type M. abscessus strain. Acquired drug resistance to macrolides and aminoglycosides was analyzed through sequencing of the 23S rRNA gene rrl and the 16S rRNA gene rrs from independent drug-resistant colonies of both strains. When the acquisition of clarithromycin resistance was examined, a different mutational profile was detected in the M. abscessus ΔnucS strain compared with the wild-type one. To summarize, M. abscessus requires the NucS-dependent noncanonical MMR pathway to prevent the emergence of drug-resistant isolates by mutation. To our knowledge, this is the first report that reveals the role of NucS in a human pathogen, and these findings have potential implications for the treatment of M. abscessus infections. IMPORTANCE Chronic infections caused by M. abscessus are an emerging challenge in public health, posing a substantial health and economic burden, especially in patients with cystic fibrosis. Treatment of M. abscessus infections with antibiotics is particularly challenging, as its complex drug resistance mechanisms, including constitutive resistance through DNA mutation, lead to high rates of treatment failure. To decipher the evolution of antibiotic resistance in M. abscessus, we studied NucS-dependent noncanonical MMR, a unique DNA repair pathway involved in genomic maintenance. Inactivation of NucS is linked to the increase of DNA mutations (hypermutation), which can confer drug resistance. Our analysis detected increased acquisition of mutations conferring resistance to first-line and second-line antibiotics. We believe that this study will improve the knowledge of how this pathogen could evolve into an untreatable infectious agent, and it uncovers a role for hypermutators in chronic infectious diseases under antibiotic pressure.

Emergency Care Gap in Brazil: Geographical Accessibility as a Proxy of Response Capacity to Tackle COVID-19.

Background: The new coronavirus disease (COVID-19) has claimed thousands of lives worldwide and disrupted the health system in many countries. As the national emergency care capacity is a crucial part of the COVID-19 response, we evaluated the Brazilian Health Care System response preparedness against the COVID-19 pandemic. Methods: A retrospective and ecological study was performed with data retrieved from the Brazilian Information Technology Department of the Public Health Care System. The numbers of intensive care (ICU) and hospital beds, general or intensivist physicians, nurses, nursing technicians, physiotherapists, and ventilators from each health region were extracted. Beds per health professionals and ventilators per population rates were assessed. A health service accessibility index was created using a two-step floating catchment area (2SFCA). A spatial analysis using Getis-Ord Gi* was performed to identify areas lacking access to high-complexity centers (HCC). Results: As of February 2020, Brazil had 35,682 ICU beds, 426,388 hospital beds, and 65,411 ventilators. In addition, 17,240 new ICU beds were created in June 2020. The South and Southeast regions have the highest rates of professionals and infrastructure to attend patients with COVID-19 compared with the northern region. The north region has the lowest accessibility to ICUs. Conclusions: The Brazilian Health Care System is unevenly distributed across the country. The inequitable distribution of health facilities, equipment, and human resources led to inadequate preparedness to manage the COVID-19 pandemic. In addition, the ineffectiveness of public measures of the municipal and federal administrations aggravated the pandemic in Brazil.