Clonagem e expressão do gene APXIV de Actinobacillus pleuropneumoniae em E. coli

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Fatores de virulência de Staphylococcus aureus

Nas últimas décadas, Staphylococcus aureus (S. aureus) adquiriu considerável importância relacionada à saúde animal e humana pela elevada patogenicidade e aumento na prevalência de cepas multirresistentes aos antibióticos. Sua elevada patogenicidade está relacionada com mecanismos multifatoriais e complexos determinados pela capacidade da bactéria de expressar uma variedade de fatores de virulência que facilitam a ocorrência de doenças. Objetivou-se com esta revisão compilar informações referentes aos fatores de virulência associados à superfície ou secretados por S. aureus que promovem adesão aos componentes da matriz extracelular do hospedeiro, danificam células hospedeiras e interferem no sistema imunológico. A implementação de estratégias para a prevenção e terapia em infecções associadas a S. aureus exige o aprofundamento dos estudos nos diferentes mecanismos de ação dos fatores de virulência

In silico evaluation of potassium USNATE: A composite promiser in the Covid-19 combat

A new coronavirus appears in China in December 2019, subsequently threatening the world, it was identified as Covid-19. Its main symptomatic characteristic is directly linked to acute respiratory failure, however there are asymptomatic cases of the disease, mainly in the group not considered at risk. For the treatment of the disease a variety ofantiviral drugs have been tested, with conflicting results. The use of computer-assisted drugs is essential for the development of new therapeutic alternatives for various diseases, once they reduce the time consumed in the initial screening tests, in addition to determining the possible mechanisms of action and reducing toxicity. In our study, we evaluated the interaction of viral components of the coronavirus with potassium usnate, salt derived from lichenic origin and with proven antimicrobial and antitumor activities. Derived from ussic acid, potassium usnate showed low energy for complex formation, this interaction occurs between the usnate salt and the structures of proteinase 3CLpro and enzyme Mpro, all key parts of Covid-19. In addition, in order to prove in silico the use of potassium usnate, they were tested and compared with other approved drugs and candidates for clinical trials to combat the new coronavirus

Phenotypic and Genotypic Characteristics and Resistance Profile of Staphylococcus spp. from Bovine Mastitis

Background: Bovine mastitis remains one of the health problems that cause the most damage to milk producers. The negative impact of mastitis is due to reduced milk production, early slaughter of females, reduced commercial value of the affected animals, losses in the genetic potential of the herd, expenses with medicines and veterinary medical assistance. Staphylococcus spp. stands out as the cause of this disease and has been able to remain in the mammary gland, becoming resistant to several antimicrobials. The aims of the present study were to characterize the phenotypes, genotypes and resistance profiles of Staphylococcus spp. isolates from bovine mastitis cases in the state of Pernambuco, Brazil.Materials, Methods & Results: These isolates were classified according to biochemical tests and the presence of the nuc gene.  The polymerase chain reaction (PCR) for amplification of the mecA and blaZ genes was used to analyze the genetic potentials of antimicrobial resistance. Isolates were also phenotypically tested for resistance to nine antimicrobials (ampicillin, doxicillin, erythromycin, gentamicin, rifampicin, cephalothin, amoxicillin, nalidixic acid and oxacillin). The genetic potentials for biofilm production were evaluated by the amplifications of the icaD, icaA and bap genes. The phenotypic test of gentian violet was used for biofilm formation analyzes. Ninety-three (93.0%) of the isolates among the Staphylococcus spp. samples were classified as Staphylococcus aureus. The lowest percentage of sensitivity observed was for amoxicillin (28.0%). All of the isolates were sensitive to erythromycin and gentamicin, and 15 (15%) exhibited sensitivity to all of the drugs tested. All of the isolates were negative for the mecA gene, and 36 (36%) were positive for blaZ. In the adhesion microplate tests, 44 (44%) of the isolates were capable of biofilm formation. Of these, seven (15.9%) were strong formers, whereas 16 (36.3%) and 21 (47.8%) were moderate and weak formers, respectively. The icaD gene was confirmed in 89 (89%) of the isolates. The icaA gene was confirmed in 61 (61%) samples, and the bap gene in 52 (52%) samples. One of the samples did not possess icaA, icaD or bap and exhibited moderate biofilm formation according to the microplate adherence test. Sixteen isolates simultaneously exhibited the three genes tested for biofilm production (icaA, icaD and bap) and were negative according to the microplate adherence test.Discussion:  The indiscriminate use of antibiotics to treat mastitis is a common practice in the study area, which may have contributed to the high proportion of herds (88.23%; 15/17) with multi-resistant isolates, constituting a selection factor for the dissemination of resistant bacteria among herds.  The absence of the mecA gene in the present study may be associated with the development of resistant bacteria through another mechanism, such as the overproduction of beta-lactamases. The results demonstrate that antimicrobial resistance occurs in Staphylococcus spp. that cause bovine mastitis in herds of Pernambuco and that these isolates have the a great capacity for biofilm formation. It is necessary to sensitize the professionals involved in the milk production chain of Brazil regarding the importance of the adequate use of antimicrobials for the treatment and control of mastitis, since studies in the country indicate the dissemination of resistant bacterial strains

OCORRÊNCIA DE BOTULISMO EM BOVINOS CONFINADOS NO RIO GRANDE DO SUL

Botulismo é a intoxicação causada pela neurotoxina produzida pelo Clostridium botulinum, caracterizando-se por paralisia flácida ou completa da musculatura esquelética. Este trabalho relata um surto de botulismo em bovinos confinados, alimentados com silagem de milho. Amostras de fígado, conteúdo intestinal e ruminal de um dos bovinos com o quadro clínico característico de botulismo e uma porção da silagem de milho foram encaminhados para análise bacteriológica. No laboratório realizaram-se bioensaio em camundongos e soroneutralização, sendo confirmada a suspeita de botulismo tipo C. Este relato visa alertar médicos veterinários e criadores que adotam o confinamento de animais, pois esta prática de manejo aumenta a suscetibilidade ao botulismo, principalmente relacionada ao tipo e qualidade do alimento consumido. PALAVRAS CHAVE: Bovinos, Clostridium botulinum, confinamento

Virulence Factors in Staphylococcus aureus and Quality of Raw Milk from Dairy Cows in a Semiarid Region of Northeastern Brazil

Background: Milk quality is considered unsatisfactory in Brazil due to factors of a social, economic, cultural, and climatic nature. Mastitis is the main disease that affects dairy herds. Microorganisms of the genus Staphylococcus are the most frequently isolated pathogens in cases of mastitis in bovines. Staphylococcus aureus requires more attention because they have the ability to develop resistance to antimicrobials used in the treatment of mastitis. Thus, the aim of the present study was to evaluate virulence factors in isolates of S. aureus as well as analyze the hygienic-sanitary quality of raw milk produced on dairy farms in a semiarid region of northeastern Brazil.Material, Methods & Results: Samples were taken from milk containers at 44 properties. Fifty-eight isolates of Staphylococcus spp. were analyzed and genotypically identified as S. aureus. In the phenotypic characterization, 56.8% (33/58) of the isolates demonstrated moderate biofilm production. In the genotypic characterization (icaA, icaD and bap genes), icaA was the most representative among the isolates. No resistance to cephalothin or oxacillin was found, but 62% (36/58) of the isolates exhibited resistance to ampicillin, amoxicillin, and penicillin. In the genotypic evaluation in response to β-lactam antibiotics, 50% (29/58) of the isolates exhibited the blaZ gene. Total bacterial counts were determined based on the standard plate count and flow cytometry, for which a significant positive correlation was found (r = 0.61, P < 0.01). The somatic cell count was also performed using flow cytometry and demonstrated that 6.8% (3/44) of the properties had values above one million cells per mL. The analysis of Staphylococcus spp. revealed that 20% (9/44) of the properties had significant counts for the production of staphylococcal enterotoxins. Regarding total coliforms, 56.8% (25/44) of the milk analyzed had counts above 1.0 x 103 CFUs/mL. There were no cases of the isolation of Pseudomonas spp. Streptococcus spp. was isolated on 6.8% (3/44) of the properties. The results of the sequencing revealed one isolate to be Lactococcus lactis and two to be Enterococcus spp.Discussion: None of the 58 isolates of S. aureus was classified as negative in the phenotypic characterization of biofilmforming capacity, which suggests the presence of genes involved in this process. Studies have shown that the molecular techniques used to identify ica genes encoding biofilm synthesis are very important for the identification of virulent strains. The isolates demonstrated resistance to β-lactam antibiotics of the class of penicillins, which are the most widely employed antimicrobial agents for the treatment of diseases in dairy herds. The presence of the blaZ gene in 50% of the isolates is in agreement with data reported in other studies developed in northeastern Brazil. In 50% (29/58) of the isolates, the presence of the blaZ gene was not observed. Of these, (8/29) were resistant to ampicillin, amoxicillin and penicillin. This is due to the existence of other bacterial mechanisms. Research has shown that some isolates possessed three mechanisms (blaZ, mecA and msrA) of antimicrobial resistance simultaneously. The results of the quality analyses demonstrate that some properties produce milk of low quality, which underscores the need for management strategies directed at reducing the contamination of the product

CARACTERIZAÇÃO BIOQUÍMICA E PERFIL DE SENSIBILIDADE AOS ANTIMICROBIANOS DE AGENTES BACTERIANOS ISOLADOS DE MASTITE SUBCLÍNICA OVINA NA REGIÃO OESTE DE SANTA CATARINA

A mastite é uma enfermidade que acomete principalmente animais com aptidão leiteira, ocasionando uma série de prejuízos aos produtores de ovinos de leite e corte. Objetivou-se avaliar o perfil de sensibilidade aos antimicrobianos dos principais agentes causadores de mastite em ovelhas. Foram analisadas 163 amostras de leite, sendo utilizado o teste Whiteside Modificado (WSM), além do cultivo das amostras em ágar sangue ovino 5% (AS). Das 163 amostras analisadas, observou-se que 23,31% e 14,72% foram positivas e fortemente positivas, respectivamente, no teste WSM. Os principais agentes isolados foram Staphylococcus spp. (31,39%), Acinetobacter spp. (10,50%), Enterobacter aerogenes (10,50%), Escherichia coli (8,20%) e Aeromonas spp. (6,70%). O perfil de sensibilidade aos antimicrobianos apresentou grande variação, com a novobiocina demonstrando o menor percentual de sensibilidade (10,46%). A maior taxa de susceptibilidade foi observada para a associação de lincomicina com estreptomicina (86,02%). Neste estudo, observou-se que os Staphylococcus spp. são os agentes comumente envolvidos nos casos de mastite subclínica em ovelhas. A associação entre lincomicina e estreptomicina e josamicina e trimetoprim constituiu as drogas mais eficientes nos testes de sensibilidade in vitro contra os agentes da mastite ovina. PALAVRAS-CHAVES: Mastite, microrganismos, resistência antimicrobiana, teste Whiteside

RESISTÊNCIA AOS ANTIMICROBIANOS DE BACTÉRIAS OBTIDAS DE CARPAS (Cyprinus carpio) CULTIVADAS EM SISTEMA SEMI-INTENSIVO

Objetivando determinar o perfil de sensibilidade às drogas antimicrobianas de bactérias presentes em carpas, foi utilizado o teste de sensibilidade de difusão em disco Kirb Bauer modificado. Foram avaliados 60 isolados bacterianos, analisados e encontrados os seguintes gêneros: Staphylococcus spp. (27), Streptococcus spp. (03), Aeromonas spp. (15), Proteus spp. (04), Acinetobacter spp. (05), Pseudomonas spp. (01) e Enterobacteriaceae (05). O perfil de sensibilidade observado foi de: amicacina (35%), amoxicilina (65%), apramicina (32%), ceftiofur (37%), doxicilina (32%), enrofloxacina (15%), josamicina (75%), lincomicina (37%), nitrofurantoina (60%), ácido nalidíxico (32%), novobiocina (82%), penicilina (70%) e sulfozotrim (40%). O índice de resistência múltipla às drogas antimicrobianas médio variou de 0,33 para Streptococcus spp até 0,71 para bactérias da família Enterobacteriaceae. Dessa forma, o maior perfil de resistência às drogas antimicrobianas testadas foi observado para novobiocina, enquanto que o menor foi observado para a enrofloxacina. Os isolados bacterianos obtidos de carpas apresentaram resistência múltipla às drogas testadas, sendo três isolados resistentes a todos os antimicrobianos testados.Palavras-chave: aquicultura; patógenos; terapia

Antimicrobial activity of silver nanoparticles synthesized by the fungus Curvularia inaequalis

Silver nanoparticles have been widely reported in literature due to their vast industrial application in different areas. In this work, we explored a simple procedure for the biosynthesis of silver nanoparticles at room temperature from the action of Curvularia inaequalis as reduction agent. The degree of aggregation and size of biosynthesized particles were optimized from a factorial design involving combined variation of three different parameters of preparation. The resulting colloidal dispersion of silver nanoparticles presented strong antimicrobial activity against Escherichia coli and Klebsiella pneumoniae in an indication that C. inaequalis represents a new potential candidate for alternative biosynthesis of silver nanoparticles with antimicrobial activity.Keywords: Antimicrobial activity, fungi, silver nanoparticlesAfrican Journal of Biotechnology Vol. 12(20), pp. 2917-292