The Contribution of Efflux Pumps in Mycobacterium abscessus Complex Resistance to Clarithromycin

The basis of drug resistance in Mycobacterium abscessus is still poorly understood. Nevertheless, as seen in other microorganisms, the efflux of antimicrobials may also play a role in M. abscessus drug resistance. Here, we investigated the role of efflux pumps in clarithromycin resistance using nine clinical isolates of M. abscessus complex belonging to the T28 erm(41) sequevar responsible for the inducible resistance to clarithromycin. The strains were characterized by drug susceptibility testing in the presence/absence of the efflux inhibitor verapamil and by genetic analysis of drug-resistance-associated genes. Efflux activity was quantified by real-time fluorometry. Efflux pump gene expression was studied by RT-qPCR upon exposure to clarithromycin. Verapamil increased the susceptibility to clarithromycin from 4- to ≥64-fold. The efflux pump genes MAB_3142 and MAB_1409 were found consistently overexpressed. The results obtained demonstrate that the T28 erm(41) polymorphism is not the sole cause of the inducible clarithromycin resistance in M. abscessus subsp. abscessus or bolletii with efflux activity providing a strong contribution to clarithromycin resistance. These data highlight the need for further studies on M. abscessus efflux response to antimicrobial stress in order to implement more effective therapeutic regimens and guidance in the development of new drugs against these bacteria

The role of urea-induced osmotic diuresis and hypernatremia in a critically ill patient: case report and literature review

Abstract Hypernatremia is a common electrolyte problem at the intensive care setting, with a prevalence that can reach up to 25%. It is associated with a longer hospital stay and is an independent risk factor for mortality. We report a case of hypernatremia of multifactorial origin in the intensive care setting, emphasizing the role of osmotic diuresis due to excessive urea generation, an underdiagnosed and a not well-known cause of hypernatremia. This scenario may occur in patients using high doses of corticosteroids, with gastrointestinal bleeding, under diets and hyperprotein supplements, and with hypercatabolism, especially during the recovery phase of renal injury. Through the present teaching case, we discuss a clinical approach to the diagnosis of urea-induced osmotic diuresis and hypernatremia, highlighting the utility of the electrolyte-free water clearance concept in understanding the development of hypernatremia

The Contribution of efflux pumps in Mycobacterium abscessus complex resistance to clarithromycin

Submitted by Janaína Nascimento ([email protected]) on 2019-11-07T13:30:51Z No. of bitstreams: 1 ve_Vianna_Júlia_etal_INI_2019.pdf: 709114 bytes, checksum: b1ed5809148e8413da3e93792838a4fa (MD5)Approved for entry into archive by Janaína Nascimento ([email protected]) on 2019-11-08T12:27:37Z (GMT) No. of bitstreams: 1 ve_Vianna_Júlia_etal_INI_2019.pdf: 709114 bytes, checksum: b1ed5809148e8413da3e93792838a4fa (MD5)Made available in DSpace on 2019-11-08T12:27:38Z (GMT). No. of bitstreams: 1 ve_Vianna_Júlia_etal_INI_2019.pdf: 709114 bytes, checksum: b1ed5809148e8413da3e93792838a4fa (MD5) Previous issue date: 2019Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Nova de Lisboa. Instituto de Higiene e Medicina Tropical. Global Health and Tropical Medicine. Lisboa, Portugal.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Universidade Nova de Lisboa. Instituto de Higiene e Medicina Tropical. Global Health and Tropical Medicine. Lisboa, Portugal.Universidade Federal de Rio Grande. Núcleo de Pesquisas em Microbiologia Médica. Rio Grande, RS, Brasil.The basis of drug resistance in Mycobacterium abscessus is still poorly understood. Nevertheless, as seen in other microorganisms, the efflux of antimicrobials may also play a role in M. abscessus drug resistance. Here, we investigated the role of efflux pumps in clarithromycin resistance using nine clinical isolates of M. abscessus complex belonging to the T28 erm(41) sequevar responsible for the inducible resistance to clarithromycin. The strains were characterized by drug susceptibility testing in the presence/absence of the efflux inhibitor verapamil and by genetic analysis of drug-resistance-associated genes. Efflux activity was quantified by real-time fluorometry. Efflux pump gene expression was studied by RT-qPCR upon exposure to clarithromycin. Verapamil increased the susceptibility to clarithromycin from 4- to ≥64-fold. The efflux pump genes MAB_3142 and MAB_1409 were found consistently overexpressed. The results obtained demonstrate that the T28 erm(41) polymorphism is not the sole cause of the inducible clarithromycin resistance in M.abscessus subsp. abscessus or bolletii with efflux activity providing a strong contribution to clarithromycin resistance. These data highlight the need for further studies on M. abscessus efflux response to antimicrobial stress in order to implement more effective therapeutic regimens and guidance in the development of new drugs against these bacteria

Whole-genome sequencing as a tool for studying the microevolution of drug-resistant serial Mycobacterium tuberculosis isolates

Treatment of drug-resistant tuberculosis requires extended use of more toxic and less effective drugs and may result in retreatment cases due to failure, abandonment or disease recurrence. It is therefore important to understand the evolutionary process of drug resistance in Mycobacterium tuberculosis. We here in describe the microevolution of drug resistance in serial isolates from six previously treated patients. Drug resistance was initially investigated through phenotypic methods, followed by genotypic approaches. The use of whole-genome sequencing allowed the identification of mutations in the katG, rpsL and rpoB genes associated with drug resistance, including the detection of rare mutations in katG and mixed populations of strains. Molecular docking simulation studies of the impact of observed mutations on isoniazid binding were also performed. Whole-genome sequencing detected 266 single nucleotide polymorphisms between two isolates obtained from one patient, suggesting a case of exogenous reinfection. In conclusion, sequencing technologies can detect rare mutations related to drug resistance, identify subpopulations of resistant strains, and identify diverse populations of strains due to exogenous reinfection, thus improving tuberculosis control by guiding early implementation of appropriate clinical and therapeutic interventions.JLCGD was a Fellow of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), PEAS is a Fellow of Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) productivity. The study had financial support by Project CNPq/Universal (401963/2016–0), CAPES (PVE-CAPES, 88881.064961/2014–01) and Fundação para a Ciência e Tecnologia (FCT), Portugal [UID/DTP/04138/2019]. This work was carried out with the support of the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) to working mission within the scope of the Capes-Print Program, Financing Code 001". JP was supported by FCT through Estímulo Individual ao Emprego Científico [CEECIND/00394/2017]. JEP is funded by a Newton Institutional Links Grant (British Council, no. 261868591). TGC is funded by the Medical Research Council UK (Grant no. MR/M01360X/1, MR/N010469/1, MR/R025576/1, and MR/R020973/1) and BBSRC (Grant no. BB/R013063/1). SC is funded by Medical Research Council UK grants (ref. MR/M01360X/1, MR/R025576/1, and MR/R020973/1). AP is funded by a faculty baseline fund (BAS/1/1020-01-01) from KAUST.info:eu-repo/semantics/publishedVersio

Aspectos fisicoquímicos e citológicos do líquido sinovial da articulação temporomandibular de equinos em diferentes idades

A análise do líquido sinovial é de grande importância para identificar alterações citológicas e químicas de afecções inflamatórias supurativas e não supurativas, hemorragias, neoplasia ou doenças infecciosas. O objetivo deste estudo foi analisar os aspectos fisicoquímicos e citológicos do líquido sinovial da articulação temporomandibular em 24 equinos hígidos, sendo 12 machos e 12 fêmeas, que foram divididos em quatro grupos, sendo um grupo controle (Gc) com a idade variando de cinco a 13 anos, grupo 1 (G1) com a idade variando entre cinco e sete anos, grupo 2 (G2) com idade variando entre oito e dez anos e grupo 3 (G3) com idade que varia entre 11 e 13 anos. O líquido sinovial foi avaliado quanto ao seu volume, pH, densidade, glicose, proteínas totais, hemácias, células nucleadas, neutró filos, linfócitos e macrófagos. Os animais do presente estudo foram tratados para alterações dentárias leves e não foi possível detectar alterações fisicoquímicas e citológicas no líquido sinovial entre os diferentes grupos