Design of hybrid molecules as antimycobacterial compounds: Synthesis of isoniazid-naphthoquinone derivatives and their activity against susceptible and resistant strains of Mycobacterium tuberculosis.

Isoniazid-naphthoquinone hybrids were synthesized and evaluated against a susceptible (H37Rv) strain and two isoniazid-resistant strains (INHR1 and INHR2) of Mycobacterium tuberculosis. The antimycobacterial activity of the derivatives was determined based on the resazurin microtiter assay and their cytotoxicity in adhered mouse monocyte macrophage J774.A1 cells (ATCC TIB-67). Of the twenty-two compounds evaluated against the three strains of M. tuberculosis, twenty-one presented some activity against the H37Rv and INHR1 (katG S315T) or INHR2 (inhA C(-5)T) strains. Compounds 1a, 2a, and 8a were effective against the INHR1 strain, and compounds 1a, 1b, 2a, 3a, 5a, 5b and 8a were effective against the INHR2 strain, with MICs in the range of 3.12-6.25 µg/mL. Compounds 1b and 5b were the most active against H37Rv, with MIC of 0.78 µg/mL. Based on the selectivity index, 1b and 5b can be considered safe as a drug candidate compounds. These results demonstrate that quinoidal compounds can be used as promising scaffolds for the development of new anti-TB drugs and hybrids with activity against M. tuberculosis-susceptible and INH-resistant strains.

Detection of Neisseria meningitidis in asymptomatic carriers in a university hospital from Brazil.

Asymptomatic meningococcus carriers in hospitals is a risk factor for acquiring meningococcal disease. Meningococcal carrier (MC) frequency was investigated in oropharyngeal swab samples collected from 200 staff members at a teaching hospital from Brazil. MC prevalence was 9% (95% CI 5-13%). Risk factors associated with MC were: mean age of 26.5 years, male gender, bar attendance frequency and number of persons/house. Of 18 isolated meningococcal strains, 14 were non-group able (NG), 3 corresponded to serogroup B and 1 to serogroup 29E. The frequency of serotypes and serosubtypes was heterogenous, with a slight predominance of serotypes 4 and 7 and serosubtypes P1.7 and P1.5. Most strains (n=13) were susceptible to the antimicrobials tested. The ctrA gene (PCR) was identified in 9 (64.3%) of the 14 NG strains, suggesting virulence in most of the NG isolated strains. Therefore, a constant surveillance of these asymptomatic carriers is required.

Mycobacterium tuberculosis of the RDRio genotype is the predominant cause of tuberculosis and associated with multidrug resistance in Porto Alegre City, South Brazil.

Spoligotyping has shown Mycobacterium tuberculosis strains to be composed of different lineages, and some of them are not just geographically restricted but also affect specific ethnic populations and are associated with outbreaks and drug resistance. We recently described a particular subtype within the Latin American-Mediterranean (LAM) family, called RD(Rio), widespread in Brazil. Moreover, recent data also indicate that RD(Rio) is present in many countries on all continents and is associated with cavitary disease and multidrug resistance (MDR). To further explore the relationship between RD(Rio) and MDR, we conducted a study in a tuberculosis (TB) reference center responsible for the care of MDR patients in Rio Grande do Sul, the southernmost Brazilian state. From a collection of 237 clinical isolates, RD(Rio) alone was responsible for one-half of all MDR cases, including one large group composed of strains with identical IS6110-restriction fragment length polymorphism (RFLP) and having the LAM5 signature. We additionally had complete data records for 96 patients and could make comparisons between the presence and absence of RD(Rio). No difference in clinical, radiological or laboratory features was observed, but a significantly greater number of cases with MDR were described in patients infected with an RD(Rio) strain (P = 0.0015). Altogether, RD(Rio) was responsible for 38% of all TB cases. These data support and confirmed previous findings that RD(Rio) is the main agent responsible for TB in Brazil and is associated with drug resistance. Considering that RD(Rio) is a globally distributed genotype, such findings raise concern about the increase in MDR in certain human populations.

Overcoming the Prokaryote/Eukaryote Barrier in Tuberculosis Treatment: A Prospect for the Repurposing and Use of Antiparasitic Drugs.

Antimicrobial resistance, the so-called silent pandemic, is pushing industry and academia to find novel antimicrobial agents with new mechanisms of action in order to be active against susceptible and drug-resistant microorganisms. In the case of tuberculosis, the need of novel anti-tuberculosis drugs is specially challenging because of the intricate biology of its causative agent, Mycobacterium tuberculosis. The repurposing of medicines has arisen in recent years as a fast, low-cost, and efficient strategy to identify novel biomedical applications for already approved drugs. This review is focused on anti-parasitic drugs that have additionally demonstrated certain levels of anti-tuberculosis activity; along with this, natural products with a dual activity against parasites and against M. tuberculosis are discussed. A few clinical trials have tested antiparasitic drugs in tuberculosis patients, and have revealed effective dose and toxicity issues, which is consistent with the natural differences between tuberculosis and parasitic infections. However, through medicinal chemistry approaches, derivatives of drugs with anti-parasitic activity have become successful drugs for use in tuberculosis therapy. In summary, even when the repurposing of anti-parasitic drugs for tuberculosis treatment does not seem to be an easy job, it deserves attention as a potential contributor to fuel the anti-tuberculosis drug pipeline.

Tetrahydropyridine derivative as efflux inhibitor in Mycobacterium abscessus.

OBJECTIVES: This study aimed to evaluate a tetrahydropyridine derivative (THP) as a potential inhibitor of the efflux mechanism and modulator of the high level of antimicrobial resistance usually observed in members of the Mycobacterium abscessus (M. abscessus) group. METHODS: The strain M. abscessus subsp. abscessus (ATCC 19997) was used as reference, in addition to three clinical isolates: M. abscessus subsp. abscessus (AT 07), and two M. abscessus subsp. bolletii (AT 46 and AT 52). The minimum inhibitory concentration (MIC) of amikacin (AMI), ciprofloxacin (CIP), clarithromycin (CLA), verapamil (VP), and THP derivative (NUNL02) was determined. RESULTS: The NUNL02 showed activity against M. abscessus; the MIC of AMI against ATCC 19997 was reduced more than 16-fold, and the MIC of CIP against AT 52 was reduced four-fold. When combined with CLA, the MIC was reduced against all tested strains. In addition, to detect and quantify the activity of the efflux mechanism, the intracellular accumulation kinetics of the fluorometric substrate ethidium bromide in the presence and absence of VP and NUNL02 were evaluated. The NUNL02 was found to be a more effective efflux inhibitor than VP, which is the classical inhibitor. CONCLUSIONS: The tetrahydropyridine derivative, NUNL02, is a promising adjuvant in the treatment of infections caused by M. abscessus.

Synthesis and in vitro antimycobacterial activity of 3-substituted 5-hydroxy-5-trifluoro[chloro]methyl-4,5-dihydro-1H-1-(isonicotinoyl) pyrazoles.

A series of 3-substituted 5-hydroxy-5-trifluoro[chloro]methyl-1H-1-isonicotinoyl-4,5-dihydropyrazoles (2a-i) were synthesised by the cyclocondensation reaction of 4-methoxy-1,1,1-trifluoro[chloro]-4-(substituted)-alk-3-en-2-ones (1a-i) and isoniazid (INH). Their in vitro antimicrobial activity was tested against INH-susceptible Mycobacterium tuberculosis H37Rv, INH-resistant clinical M. tuberculosis isolates and non-tuberculous mycobacteria. Amongst the synthesised compounds, 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-(isonicotinoyl)-pyrazole (2a) and 5-hydroxy-3-(4-methylphenyl)-5-trifluoromethyl-4,5-dihydro-1H-1-(isonicotinoyl) pyrazole (2d) were found to be the two most active agents against susceptible M. tuberculosis and several INH-resistant strains. The compound 3-(2-furyl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-(isonicotinoyl)pyrazole (2f) was active against all the INH-resistant strains regardless of the genetic background at concentrations two- to four-fold its minimum inhibitory concentration against M. tuberculosis H37Rv. These compounds were inhibitors of mycolic acid biosynthesis, in agreement with the utilisation of the INH scaffold for their design. Interestingly, the most active compound against M. tuberculosis, 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-(isonicotinoyl)-pyrazole (2a), was even more potent than INH against non-tuberculous mycobacteria.

Molecular characterization of Mycobacterium tuberculosis isolates in a region of Brazil with a high incidence of tuberculosis.

One hundred and seventy Mycobacterium tuberculosis clinical isolates were characterized by spoligotyping to evaluate the biodiversity of tubercle bacilli in a region of Brazil with a high incidence of tuberculosis (Pelotas and Rio Grande cities - Rio Grande do Sul State). The spoligotyping results were compared to the World Spoligotyping Database (Institut Pasteur de Guadeloupe), which contains data from >14,000 worldwide isolates of M. tuberculosis. The isolates clustered by spoligotyping were further characterized by IS6110-RFLP to confirm the clonal relationship. Sixty-six different spoligotypes were identified, grouping 125 of the isolates (74%). Approximately half of the isolates belonged to seven of the most frequently occurring spoligotypes in the database. Three shared types (with two or more isolates) not previously identified were given the type numbers 826, 827 and 863. An additional 45 spoligotypes were identified that did not match any existing database pattern. RFLP characterization reduced the number of isolates in most of the clusters, thereby showing a higher differentiation capacity than spoligotyping. These results highlight the importance of molecular epidemiology studies of tuberculosis in insufficiently studied regions with a high TB burden, in order to uncover the true extent of genetic diversity of the pathogen.

Detección de Neisseria meningitidis en portadores asintomáticos en un hospital universitario de Brasil / Detectio of Neisseria meningitidis in asymptomatic carriers in a university hospital from Brazil

Los portadores asintomáticos de meningococos en hospitales son un factor de riesgo (FR) para adquirir la enfermedad meningocócica. La frecuencia de portadores de meningococos fue determinada a través de colecta orofaríngea en personal de un hospital de Brasil (n = 200). La prevalencia de portadores fue del 9% (IC del 95%, 5-13%). Los FR asociados al estado de portador fueron los siguientes: edad promedio 26,5 años, sexo masculino, hábito de frecuentar bares y número de personas/casa. Entre las 18 cepas de meningococos aisladas, 14 eran no agrupables (NG), 3 correspondieron al serogrupo B y una al 29E. La frecuencia de los serotipos y serosubtipos fue heterogénea, con un ligero predominio de los serotipos 4 y 7 y de los serosubtipos P1.7 y P1.5. La mayoría de las cepas (n=13) fueron sensibles a los antimicrobianos estudiados. El gen ctrA fue identificado por PCR en 9 (64,3%) de las 14 cepas NG, lo que sugiere virulencia en la mayoría de las cepas NG aisladas. Por lo tanto, se requiere una vigilancia constante de estos portadores asintomáticos

Asymptomatic meningococcus carriers in hospitals is a risk factor for acquiring meningococcal disease. Meningococcal carrier (MC) frequency was investigated in oropharyngeal swab samples collected from 200 staff members at a teaching hospital from Brazil. MC prevalence was 9% (95% CI 5­13%). Risk factors associated with MC were: mean age of 26.5 years, male gender, bar attendance frequency and number of persons/house. Of 18 isolated meningococcal strains, 14 were non-groupable (NG), 3 corrresponded to serogroup B and 1 to serogroup 29E. The frequency of serotypes and serosubtypes was heterogenous, with a slight predominance of serotypes 4 and 7 and serosubtypes P1.7 and P1.5. Most strains (n=13) were susceptible to the antimicrobials tested. The ctrA gene (PCR) was identified in 9 (64.3%) of the 14 NG strains, suggesting virulence in most of the NG isolated strains. Therefore, a constant surveillance of these asymptomatic carriers is required