Evaluation of novel compounds as anti-bacterial or anti-virulence agents.

Antimicrobial resistance is a global threat, leading to an alarming increase in the prevalence of bacterial infections that can no longer be treated with available antibiotics. The World Health Organization estimates that by 2050 up to 10 million deaths per year could be associated with antimicrobial resistance, which would equal the annual number of cancer deaths worldwide. To overcome this emerging crisis, novel anti-bacterial compounds are urgently needed. There are two possible approaches in the fight against bacterial infections: a) targeting structures within bacterial cells, similar to existing antibiotics; and/or b) targeting virulence factors rather than bacterial growth. Here, for the first time, we provide a comprehensive overview of the key steps in the evaluation of potential new anti-bacterial and/or anti-virulence compounds. The methods described in this review include: a) in silico methods for the evaluation of novel compounds; b) anti-bacterial assays (MIC, MBC, Time-kill); b) anti-virulence assays (anti-biofilm, anti-quorum sensing, anti-adhesion); and c) evaluation of safety aspects (cytotoxicity assay and Ames test). Overall, we provide a detailed description of the methods that are an essential tool for chemists, computational chemists, microbiologists, and toxicologists in the evaluation of potential novel antimicrobial compounds. These methods are cost-effective and have high predictive value. They are widely used in preclinical studies to identify new molecular candidates, for further investigation in animal and human trials.

Genetic Diversity and Virulence of Phytopathogenic Burkholderia glumae Strains Isolated from Rice Cultivars in Valleys of the High Jungle of Perú.

Burkholderia glumae causes bacterial leaf blight in rice, and its global spread has been exacerbated by climate change. To understand the genetic diversity and virulence of B. glumae strains isolated from rice cultivars in Perú, 47 isolates were obtained from infected rice fields, all belonging to B. glumae, and confirmed by recA and toxB sequences. The BOX-PCR typing group has 38 genomic profiles, and these turn into seven variable number tandem repeats (VNTR) haplotypes. There was no correlation between clustering and geographical origin. Nineteen strains were selected for phenotypic characterization and virulence, using both the maceration level of the onion bulb proxy and inoculation of seeds of two rice cultivars. Several strains produced pigments other than toxoflavin, which correlated with onion bulb maceration. In terms of virulence at the seed level, all strains produced inhibition at the root and coleoptile level, but the severity of symptoms varied significantly between strains, revealing significant differences in pathogenicity. There is no correlation between maceration and virulence scores, probably reflecting different virulence mechanisms depending on the host infection stage. This is the first study to evaluate the VNTR diversity and virulence of Peruvian strains of B. glumae in two commercial cultivars.

Pseudomonas aeruginosa associated pulmonary infections and in vitro amplification virulent rhamnolipid (rhlR) gene / Infecções pulmonares associadas a Pseudomonas aeruginosa e gene ramnolipídeo virulento (rhlR) da amplificação in vitro

Background: Pseudomonas aeruginosa is a common opportunistic pathogenic bacterium with the ability to develop a strong communication pathway by quorum sensing system and different virulent factors. Among the various important secretions of P. aeruginosa rhamnolipid is important biological detergent, believed to be involved in the development of the biofilm and intercellular communication. It readily dissolves the lung surfactants that are then easily catalyzed by the phospholipases and in this way is involved in the acute pulmonary infection. Objective: research work was designed to investigate virulence and gene associated with virulence in P. aeruginosa responsible for pulmonary infections. Methods: In current study polymerase chain reaction (PCR) was used for the detection of the rhlR (rhamnolipid encoding) gene of isolated strains. A number of assays were performed that ensured its virulent behavior. Disc diffusion method was used to check its antibiotic resistance. Isolated strains were resistant to a number of antibiotics applied. Result: It was found that males are more prone to respiratory infections as compared to females. Male members with age of 44-58 and 59-73 are at a higher risk, while females with age of 44-58 are also at a risk of pulmonary infections. Antibiotic resistance was observed by measuringzone of inhibition in strains GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 and GCU-SG-M6. GCU-SG-M2 was resistant to fluconazole (FLU), clarithromycin (CLR), cefixime (CFM) and Penicillin (P10). No zone of inhibition was observed. But it showed unusual diffused zone around the Ak and MEM antibiotic discs. rhl R gene and 16s rRNA gene were characterized and analyzed. Conclusion: Findings from current study would help[...].

Antecedentes: Pseudomonas aeruginosa é uma bactéria patogênica oportunista comum, com a capacidade de desenvolver uma forte via de comunicação pelo sistema de detecção de quorum e diferentes fatores virulentos. Entre as várias secreções importantes de P. aeruginosa rhamnolipid, há um importante detergente biológico, que se acredita estar envolvido no desenvolvimento do biofilme e na comunicação intercelular. Dissolve rapidamente os surfactantes pulmonares que são facilmente catalisados pelas fosfolipases e, dessa maneira, estão envolvidos na infecção pulmonar aguda. Objetivo: O trabalho de pesquisa foi desenhado para investigar a virulência e o gene associado à virulência em P. aeruginosa responsável por infecções pulmonares. Métodos: No presente estudo, a reação em cadeia da polimerase (PCR) foi utilizada para a detecção do gene rhlR (codificação ramnolipídeo) de cepas isoladas. Foram realizados vários ensaios que garantiram seu comportamento virulento. O método de difusão em disco foi utilizado para verificar sua resistência a antibióticos. As estirpes isoladas foram resistentes a vários antibióticos aplicados. Resultado: Verificou-se que os homens são mais propensos a infecções respiratórias em comparação às mulheres. Membros do sexo masculino com idade entre 44 e 58 e 59 e 73 anos correm maior risco, enquanto mulheres com idade entre 44 e 58 anos também correm risco de infecções pulmonares. A resistência aos antibióticos foi observada medindo a zona de inibição nas cepas GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 e GCU-SG-M6. O GCU-SG-M2 foi resistente ao fluconazol (FLU), claritromicina (CLR), cefixima (CFM) e penicilina (P10). Nenhuma zona de inibição foi observada. Mas se notou uma zona difusa incomum ao redor dos discos antibióticos Ak e MEM. Os genes rhl R e 16s rRNA foram caracterizados e analisados. Conclusão: As conclusões do presente estudo ajudariam a aumentar a conscientização sobre a resistência a antibióticos de, [...].

Pseudomonas aeruginosa associated pulmonary infections and in vitro amplification virulent rhamnolipid (rhlR) gene

Abstract Background Pseudomonas aeruginosa is a common opportunistic pathogenic bacterium with the ability to develop a strong communication pathway by quorum sensing system and different virulent factors. Among the various important secretions of P. aeruginosa rhamnolipid is important biological detergent, believed to be involved in the development of the biofilm and intercellular communication. It readily dissolves the lung surfactants that are then easily catalyzed by the phospholipases and in this way is involved in the acute pulmonary infection. Objective research work was designed to investigate virulence and gene associated with virulence in P. aeruginosa responsible for pulmonary infections. Methods In current study polymerase chain reaction (PCR) was used for the detection of the rhlR (rhamnolipid encoding) gene of isolated strains. A number of assays were performed that ensured its virulent behavior. Disc diffusion method was used to check its antibiotic resistance. Isolated strains were resistant to a number of antibiotics applied. Result It was found that males are more prone to respiratory infections as compared to females. Male members with age of 44-58 and 59-73 are at a higher risk, while females with age of 44-58 are also at a risk of pulmonary infections. Antibiotic resistance was observed by measuring zone of inhibition in strains GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 and GCU-SG-M6. GCU-SG-M2 was resistant to fluconazole (FLU), clarithromycin (CLR), cefixime (CFM) and Penicillin (P10). No zone of inhibition was observed. But it showed unusual diffused zone around the Ak and MEM antibiotic discs. rhl R gene and 16s rRNA gene were characterized and analyzed. Conclusion Findings from current study would help in raising awareness about antibiotic resistance of P. aeruginosa, and also the sequence of rhl R gene can be used as the diagnostic marker sequence to identify the virulent rhl R gene sequence from the samples when isolated from sputum of Pneumonia patients.

Resumo Antecedentes Pseudomonas aeruginosa é uma bactéria patogênica oportunista comum, com a capacidade de desenvolver uma forte via de comunicação pelo sistema de detecção de quorum e diferentes fatores virulentos. Entre as várias secreções importantes de P. aeruginosa rhamnolipid, há um importante detergente biológico, que se acredita estar envolvido no desenvolvimento do biofilme e na comunicação intercelular. Dissolve rapidamente os surfactantes pulmonares que são facilmente catalisados pelas fosfolipases e, dessa maneira, estão envolvidos na infecção pulmonar aguda. Objetivo O trabalho de pesquisa foi desenhado para investigar a virulência e o gene associado à virulência em P. aeruginosa responsável por infecções pulmonares. Métodos No presente estudo, a reação em cadeia da polimerase (PCR) foi utilizada para a detecção do gene rhlR (codificação ramnolipídeo) de cepas isoladas. Foram realizados vários ensaios que garantiram seu comportamento virulento. O método de difusão em disco foi utilizado para verificar sua resistência a antibióticos. As estirpes isoladas foram resistentes a vários antibióticos aplicados. Resultado Verificou-se que os homens são mais propensos a infecções respiratórias em comparação às mulheres. Membros do sexo masculino com idade entre 44 e 58 e 59 e 73 anos correm maior risco, enquanto mulheres com idade entre 44 e 58 anos também correm risco de infecções pulmonares. A resistência aos antibióticos foi observada medindo a zona de inibição nas cepas GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 e GCU-SG-M6. O GCU-SG-M2 foi resistente ao fluconazol (FLU), claritromicina (CLR), cefixima (CFM) e penicilina (P10). Nenhuma zona de inibição foi observada. Mas se notou uma zona difusa incomum ao redor dos discos antibióticos Ak e MEM. Os genes rhl R e 16s rRNA foram caracterizados e analisados. Conclusão As conclusões do presente estudo ajudariam a aumentar a conscientização sobre a resistência a antibióticos de P. aeruginosa e, também, a sequência do gene rhl R pode ser usada como sequência de diagnóstico para identificar a sequência virulenta do gene rhl R das amostras quando isoladas do escarro de pacientes com pneumonia.

Pseudomonas aeruginosa associated pulmonary infections and in vitro amplification virulent rhamnolipid (rhlR) gene / Infecções pulmonares associadas a Pseudomonas aeruginosa e gene ramnolipídeo virulento (rhlR) da amplificação in vitro

Background: Pseudomonas aeruginosa is a common opportunistic pathogenic bacterium with the ability to develop a strong communication pathway by quorum sensing system and different virulent factors. Among the various important secretions of P. aeruginosa rhamnolipid is important biological detergent, believed to be involved in the development of the biofilm and intercellular communication. It readily dissolves the lung surfactants that are then easily catalyzed by the phospholipases and in this way is involved in the acute pulmonary infection. Objective: research work was designed to investigate virulence and gene associated with virulence in P. aeruginosa responsible for pulmonary infections. Methods: In current study polymerase chain reaction (PCR) was used for the detection of the rhlR (rhamnolipid encoding) gene of isolated strains. A number of assays were performed that ensured its virulent behavior. Disc diffusion method was used to check its antibiotic resistance. Isolated strains were resistant to a number of antibiotics applied. Result: It was found that males are more prone to respiratory infections as compared to females. Male members with age of 44-58 and 59-73 are at a higher risk, while females with age of 44-58 are also at a risk of pulmonary infections. Antibiotic resistance was observed by measuring zone of inhibition in strains GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCU-SG-M2, GCU-SG-M1 and GCU-SG-M6. GCU-SG-M2 was resistant to fluconazole (FLU), clarithromycin (CLR), cefixime (CFM) and Penicillin (P10). No zone of inhibition was observed. But it showed unusual diffused zone around the Ak and MEM antibiotic discs. rhl R gene and 16s rRNA gene were characterized and analyzed. Conclusion: Findings from current study would help in raising awareness about antibiotic resistance of P. aeruginosa, and also the sequence of rhl R gene can be used as the diagnostic marker sequence to identify the virulent rhl R gene sequence from the samples when isolated from sputum of Pneumonia patients.

Antecedentes: Pseudomonas aeruginosa é uma bactéria patogênica oportunista comum, com a capacidade de desenvolver uma forte via de comunicação pelo sistema de detecção de quorum e diferentes fatores virulentos. Entre as várias secreções importantes de P. aeruginosa rhamnolipid, há um importante detergente biológico, que se acredita estar envolvido no desenvolvimento do biofilme e na comunicação intercelular. Dissolve rapidamente os surfactantes pulmonares que são facilmente catalisados pelas fosfolipases e, dessa maneira, estão envolvidos na infecção pulmonar aguda. Objetivo: O trabalho de pesquisa foi desenhado para investigar a virulência e o gene associado à virulência em P. aeruginosa responsável por infecções pulmonares. Métodos: No presente estudo, a reação em cadeia da polimerase (PCR) foi utilizada para a detecção do gene rhlR (codificação ramnolipídeo) de cepas isoladas. Foram realizados vários ensaios que garantiram seu comportamento virulento. O método de difusão em disco foi utilizado para verificar sua resistência a antibióticos. As estirpes isoladas foram resistentes a vários antibióticos aplicados. Resultado: Verificou-se que os homens são mais propensos a infecções respiratórias em comparação às mulheres. Membros do sexo masculino com idade entre 44 e 58 e 59 e 73 anos correm maior risco, enquanto mulheres com idade entre 44 e 58 anos também correm risco de infecções pulmonares. A resistência aos antibióticos foi observada medindo a zona de inibição nas cepas GCU-SG-M4, GCU-SG-M3, GCU-SG-M5, GCUSG-M2, GCU-SG-M1 e GCU-SG-M6. O GCU-SG-M2 foi resistente ao fluconazol (FLU), claritromicina (CLR), cefixima (CFM) e penicilina (P10). Nenhuma zona de inibição foi observada. Mas se notou uma zona difusa incomum ao redor dos discos antibióticos Ak e MEM. Os genes rhl R e 16s rRNA foram caracterizados e analisados. Conclusão: As conclusões do presente estudo ajudariam a aumentar a conscientização sobre a resistência a antibióticos de P. aeruginosa e, também, a sequência do gene rhl R pode ser usada como sequência de diagnóstico para identificar a sequência virulenta do gene rhl R das amostras quando isoladas do escarro de pacientes com pneumonia.

Susceptibility of Various Developmental Stages of the Fall Armyworm, Spodoptera frugiperda, to Entomopathogenic Nematodes.

The fall armyworm, Spodoptera frugiperda, which is native to Central and South America, has recently invaded Africa and Asia, causing serious damage to various crops. Although management to date has been largely unsuccessful, entomopathogenic nematodes (EPNs) are a potential biological control agent that could be used to control the late larval and pupal stages of S. frugiperda that dwell under the ground. Here, we compared the virulence of seven EPNs against larval and pupal stages of S. frugiperda. In a Petri dish assay, both Heterorhabditis indica and Steinernema carpocapsae were highly virulent against younger larvae, whereas S. arenarium and S. longicaudum were highly virulent against older larvae. In contrast, H. bacteriophora, Heterorhabditis sp., and S. kushidai showed low virulence against all larval stages. In soil column and pot assays, H. indica, S. carpocapsae, and S. longicaudum were highly virulent against late larval and pupal stages compared with the other EPN species. Thus, H. indica, S. carpocapsae, and S. longicaudum are recommended for the biological control of S. frugiperda. Our study provides important information of EPNs for the practical application of biological control of fall armyworm.

Characterisation of Bergeyella spp. isolated from the nasal cavities of piglets.

The aim of this study was to characterise bacteria in the genus Bergeyella isolated from the nasal passages of healthy piglets. Nasal swabs from 3 to 4 week-old piglets from eight commercial domestic pig farms and one wild boar farm were cultured under aerobic conditions. Twenty-nine Bergeyella spp. isolates were identified by partial 16S rRNA gene sequencing and 11 genotypes were discriminated by enterobacterial repetitive intergenic consensus (ERIC)-PCR. Bergeyella zoohelcum and Bergeyella porcorum were identified within the 11 genotypes. Bergeyella spp. isolates exhibited resistance to serum complement and phagocytosis, poor capacity to form biofilms and were able to adhere to epithelial cells. Maneval staining was consistent with the presence of a capsule. Multiple drug resistance (resistance to three or more classes of antimicrobial agents) was present in 9/11 genotypes, including one genotype isolated from wild boar with no history of antimicrobial use. In conclusion, Bergeyella spp. isolates from the nasal cavities of piglets showed some in vitro features indicative of a potential for virulence. Further studies are necessary to identify the role of Bergeyella spp. in disease and within the nasal microbiota of pigs.

Pseudomonas syringae pv. tomato DC3000 polymutants deploying coronatine and two type III effectors produce quantifiable chlorotic spots from individual bacterial colonies in Nicotiana benthamiana leaves.

Primary virulence factors of Pseudomonas syringae pv. tomato DC3000 include the phytotoxin coronatine (COR) and a repertoire of 29 effector proteins injected into plant cells by the type III secretion system (T3SS). DC3000 derivatives differentially producing COR, the T3SS machinery and subsets of key effectors were constructed and assayed in leaves of Nicotiana benthamiana. Bacteria were inoculated by the dipping of whole plants and assayed for population growth and the production of chlorotic spots on leaves. The strains fell into three classes. Class I strains are T3SS+ but functionally effectorless, grow poorly in planta and produce faint chlorotic spots only if COR+ . Class II strains are T3SS- or, if T3SS+ , also produce effectors AvrPtoB and HopM1. Class II strains grow better than class I strains in planta and, if COR+ , produce robust chlorotic spots. Class III strains are T3SS+ and minimally produce AvrPtoB, HopM1 and three other effectors encoded in the P. syringae conserved effector locus. These strains differ from class II strains in growing better in planta, and produce chlorotic spots without COR if the precursor coronafacic acid is produced. Assays for chlorotic spot formation, in conjunction with pressure infiltration of low-level inoculum and confocal microscopy of fluorescent protein-labelled bacteria, revealed that single bacteria in the apoplast are capable of producing colonies and associated leaf spots in a 1 : 1 : 1 manner. However, COR makes no significant contribution to the bacterial colonization of the apoplast, but, instead, enables a gratuitous, semi-quantitative, surface indicator of bacterial growth, which is determined by the strain's effector composition.

Infection assays in Arabidopsis reveal candidate effectors from the poplar rust fungus that promote susceptibility to bacteria and oomycete pathogens.

Fungi of the Pucciniales order cause rust diseases which, altogether, affect thousands of plant species worldwide and pose a major threat to several crops. How rust effectors-virulence proteins delivered into infected tissues to modulate host functions-contribute to pathogen virulence remains poorly understood. Melampsora larici-populina is a devastating and widespread rust pathogen of poplar, and its genome encodes 1184 identified small secreted proteins that could potentially act as effectors. Here, following specific criteria, we selected 16 candidate effector proteins and characterized their virulence activities and subcellular localizations in the leaf cells of Arabidopsis thaliana. Infection assays using bacterial (Pseudomonas syringae) and oomycete (Hyaloperonospora arabidopsidis) pathogens revealed subsets of candidate effectors that enhanced or decreased pathogen leaf colonization. Confocal imaging of green fluorescent protein-tagged candidate effectors constitutively expressed in stable transgenic plants revealed that some protein fusions specifically accumulate in nuclei, chloroplasts, plasmodesmata and punctate cytosolic structures. Altogether, our analysis suggests that rust fungal candidate effectors target distinct cellular components in host cells to promote parasitic growth.