Challenges and expectations: a journey to a syphilis vaccination

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In vitro selection of Neisseria gonorrhoeae unveils novel mutations associated with extended-spectrum cephalosporin resistance

The emergence of Neisseria gonorrhoeae strains resistant to extended-spectrum cephalosporins (ESCs) is a worldwide concern because this class of antibiotics represents the last empirical treatment option for gonorrhea. The abusive use of antimicrobials may be an essential factor for the emergence of ESC resistance in N. gonorrhoeae. Cephalosporin resistance mechanisms have not been fully clarified. In this study, we mapped mutations in the genome of N. gonorrhoeae isolates after resistance induction with cefixime and explored related metabolic pathways. Six clinical isolates with different antimicrobial susceptibility profiles and genotypes and two gonococcal reference strains (WHO F and WHO Y) were induced with increasing concentrations of cefixime. Antimicrobial susceptibility testing was performed against six antimicrobial agents before and after induction. Clinical isolates were whole-genome sequenced before and after induction, whereas reference strains were sequenced after induction only. Cefixime resistance induction was completed after 138 subcultures. Several metabolic pathways were affected by resistance induction. Five isolates showed SNPs in PBP2. The isolates M111 and M128 (ST1407 with mosaic penA-34.001) acquired one and four novel missense mutations in PBP2, respectively. These isolates exhibited the highest minimum inhibitory concentration (MIC) for cefixime among all clinical isolates. Mutations in genes contributing to ESC resistance and in other genes were also observed. Interestingly, M107 and M110 (ST338) showed no mutations in key determinants of ESC resistance despite having a 127-fold increase in the MIC of cefixime. These findings point to the existence of different mechanisms of acquisition of ESC resistance induced by cefixime exposure. Furthermore, the results reinforce the importance of the gonococcal antimicrobial resistance surveillance program in Brazil, given the changes in treatment protocols made in 2017 and the nationwide prevalence of sequence types that can develop resistance to ESC

Genomic epidemiology of Mycobacterium tuberculosis in Santa Catarina, Southern Brazil

Mycobacterium tuberculosis (M.tb), the pathogen responsible for tuberculosis (TB) poses as the major cause of death among infectious diseases. The knowledge about the molecular diversity of M.tb enables the implementation of more effective surveillance and control measures and, nowadays, Whole Genome Sequencing (WGS) holds the potential to produce high-resolution epidemiological data in a high-throughput manner. Florianópolis, the state capital of Santa Catarina (SC) in south Brazil, shows a high TB incidence (46.0/100,000). Here we carried out a WGS-based evaluation of the M.tb strain diversity, drug-resistance and ongoing transmission in the capital metropolitan region. Resistance to isoniazid, rifampicin, streptomycin was identified respectively in 4.0% (n = 6), 2.0% (n = 3) and 1.3% (n = 2) of the 151 studied strains by WGS. Besides, resistance to pyrazinamide and ethambutol was detected in 0.7% (n = 1) and reistance to ethionamide and fluoroquinolone (FQ) in 1.3% (n = 2), while a single (0.7%) multidrug-resistant (MDR) strain was identified. SNP-based typing classified all isolates into M.tb Lineage 4, with high proportion of sublineages LAM (60.3%), T (16.4%) and Haarlem (7.9%). The average core-genome distance between isolates was 420.3 SNPs, with 43.7% of all isolates grouped across 22 genomic clusters thereby showing the presence of important ongoing TB transmission events. Most clusters were geographically distributed across the study setting which highlights the need for an urgent interruption of these large transmission chains. The data conveyed by this study shows the presence of important and uncontrolled TB transmission in the metropolitan area and provides precise data to support TB control measures in this region.publishersversionpublishe

Search for antimicrobial activity among fifty-two natural and synthetic compounds identifies anthraquinone and polyacetylene classes that inhibit Mycobacterium tuberculosis

Drug-resistant tuberculosis threatens to undermine global control programs by limiting treatment options. New antimicrobial drugs are required, derived from new chemical classes. Natural products offer extensive chemical diversity and inspiration for synthetic chemistry. Here, we isolate, synthesize and test a library of 52 natural and synthetic compounds for activity against Mycobacterium tuberculosis. We identify seven compounds as antimycobacterial, including the natural products isobavachalcone and isoneorautenol, and a synthetic chromene. The plant-derived secondary metabolite damnacanthal was the most active compound with the lowest minimum inhibitory concentration of 13.07 μg/mL and a favorable selectivity index value. Three synthetic polyacetylene compounds demonstrated antimycobacterial activity, with the lowest MIC of 17.88 μg/mL. These results suggest new avenues for drug discovery, expanding antimicrobial compound chemistries to novel anthraquinone and polyacetylene scaffolds in the search for new drugs to treat drug-resistant bacterial diseases

WITHDRAWN: Herbalists, traditional healers and pharmacists: a view of the tuberculosis in Ghana

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/<10.1590/0102-695X2014241405>. The duplicate article has therefore been withdrawn.The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy

Assessment of a Treponemal Competitive Enzyme Immunoassay for Syphilis Antibody Screening in 23,531 Serum Samples from a Low Prevalence Population.

Foram testadas, com o teste não treponêmico VDRL e com o teste treponêmico imunoenzimático de competição, 23.531 amostras de soros, coletados em todas as regiões do Brasil, com o objetivo de verificar o comportamento do teste imunoenzimático treponêmico na triagem de amostras. A prevalência obtida foi de 0,63% com o VDRL e de 0,84% para o teste imunoenzimático. A análise dos dados foi feita comparando-se os resultados dos dois testes com os resultados do teste treponêmico de imunofluorescência indireta (FTA-ABS), considerado como teste de referência. No total, 1120 amostras foram submetidas ao teste FTA-ABS, incluindo todas as que foram reagentes em qualquer um dos testes de triagem e 872 amostras negativas. Amostras com resultados discordantes entre os testes foram submetidas a um teste imunoenzimático do tipo Western blot. Nas amostras por nós estudadas, o teste imunoenzimático apresentou sensibilidade de 89,95% e especificidade de 99,78%, muito superior aos 55,11% de sensibilidade e 97,43% de especificidade que encontramos para o VDRL. Os resultados dos testes detectaram positividade em amostras diferentes portanto, recomendamos utilizar a associação dos dois testes, como método de triagem, quando se trata de populações de baixa prevalência. Resultados preliminares do Western blot sugerem a participação doas proteínas de 43 kD, 17 kD e 15,5 kD na reação de ELISA treponêmico competitivo.The VDRL, a non treponemal test, and a treponemal competitive ELISA were used to test 23,531 serum samples, collected from conscript men throughout Brazil, with the objective of assessing the performance of the competitive ELISA on the screening of serum samples. The VDRL showed a prevalence of 0.63% contrasting with a 0.84% prevalence showed by the competitive ELISA. The results obtained with the two tests were then compared to those obtained by fluorescent treponemal antibody absorption (FTA-ABS) test which is considered the gold standard method for detection of antibodies for syphilis. A total number of 1,120 samples, which included all that were reagent in at least one of the screening test plus 872 that were negative in both tests, were submitted to the FTA_ABS test. In addition, some of the samples that presented discrepant results between the two tests studied were also submitted to the Western blot test. The results of the screening tests showed an 89.95% sensitivity and a 99.78% specificity for the competitive ELISA, which are much higher than the 55.11% sensitivity and 97.43% specificity presented by the VDRL. Also, the tests detected positivity in different samples. In conclusion, we recommended the use in tandem of both tests as screening for syphilis antibodies in low prevalence populations. In addition, the results of the Western blot seemed to suggest the positivity of the ELISA becoming non reactive after treatment of the patient and that the 43 kD, 17 kD and 15 kD proteins are the main proteins involved in the ELISA competitive reaction

Assessment of a Treponemal Competitive Enzyme Immunoassay for Syphilis Antibody Screening in 23,531 Serum Samples from a Low Prevalence Population.

Foram testadas, com o teste não treponêmico VDRL e com o teste treponêmico imunoenzimático de competição, 23.531 amostras de soros, coletados em todas as regiões do Brasil, com o objetivo de verificar o comportamento do teste imunoenzimático treponêmico na triagem de amostras. A prevalência obtida foi de 0,63% com o VDRL e de 0,84% para o teste imunoenzimático. A análise dos dados foi feita comparando-se os resultados dos dois testes com os resultados do teste treponêmico de imunofluorescência indireta (FTA-ABS), considerado como teste de referência. No total, 1120 amostras foram submetidas ao teste FTA-ABS, incluindo todas as que foram reagentes em qualquer um dos testes de triagem e 872 amostras negativas. Amostras com resultados discordantes entre os testes foram submetidas a um teste imunoenzimático do tipo Western blot. Nas amostras por nós estudadas, o teste imunoenzimático apresentou sensibilidade de 89,95% e especificidade de 99,78%, muito superior aos 55,11% de sensibilidade e 97,43% de especificidade que encontramos para o VDRL. Os resultados dos testes detectaram positividade em amostras diferentes portanto, recomendamos utilizar a associação dos dois testes, como método de triagem, quando se trata de populações de baixa prevalência. Resultados preliminares do Western blot sugerem a participação doas proteínas de 43 kD, 17 kD e 15,5 kD na reação de ELISA treponêmico competitivo.The VDRL, a non treponemal test, and a treponemal competitive ELISA were used to test 23,531 serum samples, collected from conscript men throughout Brazil, with the objective of assessing the performance of the competitive ELISA on the screening of serum samples. The VDRL showed a prevalence of 0.63% contrasting with a 0.84% prevalence showed by the competitive ELISA. The results obtained with the two tests were then compared to those obtained by fluorescent treponemal antibody absorption (FTA-ABS) test which is considered the gold standard method for detection of antibodies for syphilis. A total number of 1,120 samples, which included all that were reagent in at least one of the screening test plus 872 that were negative in both tests, were submitted to the FTA_ABS test. In addition, some of the samples that presented discrepant results between the two tests studied were also submitted to the Western blot test. The results of the screening tests showed an 89.95% sensitivity and a 99.78% specificity for the competitive ELISA, which are much higher than the 55.11% sensitivity and 97.43% specificity presented by the VDRL. Also, the tests detected positivity in different samples. In conclusion, we recommended the use in tandem of both tests as screening for syphilis antibodies in low prevalence populations. In addition, the results of the Western blot seemed to suggest the positivity of the ELISA becoming non reactive after treatment of the patient and that the 43 kD, 17 kD and 15 kD proteins are the main proteins involved in the ELISA competitive reaction

Quality of sputum in the performance of polymerase chain reaction for diagnosis of pulmonary tuberculosis

SETTING: faster alternative techniques are required to improve the diagnosis and control of pulmonary tuberculosis. OBJECTIVE: To evaluate the sample quality in the performance of PCR for diagnosis of pulmonary tuberculosis. METHOD: during one year, sputum samples were collected from 72 pulmonary tuberculosis patients and 12 non-tuberculosis controls, which were admitted to the Nereu Ramos hospital, Florianópolis city, Brazil. The samples were subjected to Ziehl-Neelsen-stained sputum smear microscopy and Lowestein-Jensen medium culture, which were defined as gold standard tests for mycobacteria, and polymerase chain reaction (PCR). Those samples that presented more than 40% of viable cells and less than 25% of epithelial cells were defined as high quality samples. RESULTS: PCR showed sensitivity of 55.6%, specificity of 41.7%, positive predictive value of 85.1%, negative predictive value of 13.5%, and accuracy of 53.6%. High quality samples showed sensitivity of 72.4%, specificity of 50%, positive predictive value of 91.3%, negative predictive value of 20%, and accuracy of 69.7%. Low quality samples showed sensitivity of 44.2%, specificity of 37.5%, positive predictive value of 79.2%, negative predictive value of 11.1%, and accuracy of 43.1%. CONCLUSION: use of high quality samples improved significantly the PCR performance, especially on their sensitivity and positive predictive values