Search

Escherichia coli is a normal inhabitant of the enteric microflora of human and animal. Intestinal and extra-intestinal infections caused by E. coli in mammals are characterized by the presence of diversity of virulence factors. In addition it can be isolated from environment surrounding human and animal farms. E. coli is the main environmental pathogen causing clinical mastitis in dairy cattle. It causes a wide range of disease severity, from changes seen exclusively in milk to severe systemic signs. The severity of clinical mastitis has been conventionally classified into three levels: mild (grade 1), moderate (score 2), and severe (score 3). Recently, reports of cases of bovine mastitis caused by environmental agents have been on the rise, in particular in countries that have succeeded in controlling contagious microorganisms. Unlike enteric and certain extra-enteric conditions in domestic animals and humans, the impact of virulence factors on the occurrence of bovine mastitis due to E. coli, as well as the clinical severity of the cases, is not fully understood. In this regard, the present study reviewed the most relevant virulence factors of E. coli in human and animals, with emphasis in bovine mastitis. Escherichia coli (E. coli) é um micro-organismo que pertence a microbiota entérica de humanos e animais. As afecções entéricas e extra-entéricas causadas por E.coli em mamíferos são caracterizadas pela presença de ampla diversidade de fatores de virulência. Além disso, este micro-organismo também pode ser isolado em ambientes de produção animal. E. coli é o principal agente ambiental que causa mastite clínica em vacas leiteiras, provocando sinais clínicos que podem variar desde mudanças observadas exclusivamente no leite até sinais sistêmicos graves. A gravidade da mastite clínica é convencionalmente classificada em três níveis: leve (grau 1), moderada (grau 2), e grave (grau 3). Atualmente, os relatos de casos de mastite bovina causada por agentes ambientais têm aumentando, principalmente nos países que conseguiram controlar os micro-organismos contagiosos. Diferentemente de infecções entéricas e certas extra-entéricas em humanos e animais, o impacto dos fatores de virulência de E. coli na ocorrência de mastite bovina não é totalmente compreendido, assim como na gravidade clínica dos casos. Neste contexto, o presente estudo revisou os fatores de virulência de E. coli mais relevantes para humanos e animais, com ênfase na mastite bovina.

The α subunit (ATP1) is a vital component of mitochondrial complex V which counts for the majority of cellular ATP production in a living organism. Nevertheless, how the α subunit influences other cellular processes such as pathogenicity in Candida albicans remains poorly understood. To address this question, ATP1 mutant (atp1Δ/Δ) and the gene-reconstituted strain (atp1Δ/ATP1) have been constructed in this study and their pathogenicity-related traits are compared to those of wild type (WT). In a murine model of disseminated candidiasis, atp1Δ/Δ infected mice have a significantly higher survival rate and experience a lower fungal burden in tissues. In in vitro studies atp1Δ/Δ lose a capability to damage or destroy macrophages and endothelial cells. Furthermore, atp1Δ/Δ is not able to grow under either glucose-denial conditions or high H2O2 conditions, both of which are associated with the potency of the macrophages to kill C. albicans. Defects in filamentation and biofilm formation may impair the ability of atp1Δ/Δ to penetrate host cells and establish robust colonies in the host tissues. In concert with these pathogenic features, intracellular ATP levels of atp1Δ/Δ can drop to 1/3 of WT level. These results indicate that the α subunit of Complex V play important roles in C. albicans pathogenicity.

Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic.

Cow mastitis caused by Escherichia coli (E. coli) exhibits various local and systemic clinical signs at varying degrees of severity. The aim this study was to elucidate the virulence properties, antibiotic resistance and phylogenetics of 56 E. coli strains. Of all the studied strains, 12 were positive for hemolytic properties and 38 were positive for biofilm production. Additionally, 55 of the strains were positive for multiple resistances in bacteriological tests. PCR analysis revealed that 42 strains carried the traT gene, 20 strains had the shiga toxin gene (stx1-stx2), and 8 strains carried the intimin gene (eae), but all strains were negative for aerobactin gene (aer). All strains encoding shiga toxin genes were also positive for stx1, but only 4 strains were positive for stx2. There were no significant differences in virulence genes between antibiotic-resistant and antibiotic-susceptible strains. The random amplifi ed polymorphic DNA-polymerase chain reaction patterns revealed the existence of 13 main groups with 4 subgroups of E. coli. In this study, E. coli strains causing intramammary infections and originating from various sources might show resistance against common antibiotics. Pathogenity of E. coli that cause clinical mastitis, and prognosis of the infection might be predicted by obtaining the traT Mastitis kod krava, izazvan bakterijom Escherichia coli (E. coli) ima različite lokalne i sistemske kliničke simptome čiji stepen izraženosti značajno varira. Cilj ispitivanja je bio da se ustanove virulentni faktori, rezistencija na antibiotike kao i fi logeneza 56 sojeva E. coli. Od svih ispitivanih sojeva, 12 je bilo pozitivno na hemolitičku aktivnost a 38 je proizvodilo biofi lm. Pored ovoga, 55 sojeva je bilo pozitivno na multiplu rezistenciju u bakteriološkim testovima. PCR analiza je pokazala da je 42 soja posedovalo traT gen, 20 sojeva je posedovalo shiga toksin gen (stx1-stx2), a 8 sojeva je posedovalo intimin gen (eae), ali su svi ispitivani sojevi bili negativni na aerobaktin gen (aer). Svi sojevi koji su posedovali shiga toksin gene bili su pozitivni i na stx1, ali je samo 4 soja bilo pozitivno na stx2 gen. Nije bilo značajnih razlika u genima virulencije između antibiotik-rezistentnih i antibiotik-osetljivih sojeva. Polimorfna DNK-PCR je pokazala da postoji 13 osnovnih grupa sa 4 podbrupe E. coli. U ovoj studiji, E. coli sojevi Cengiz et al. 425 koji su izazivali intramamarne infekcije i koji su poticali iz različitih izvora pokazali su razistenciju na uobičajene antibiotike. Patogenost E. coli koja izaziva klinčke forme mastitisa kao i prognoza infekcije može da se predvidi na osnovu podataka o prisustvu traT gena. Pored ovoga, rezistencija na antibiotike treba da se ispita na genetskoj osnovi u cilju detekcije povezanosti između faktora virulencije i rezistencije na antibiotike. U terenskim uslovima, razvoj rezistencije na antibiotike je osnovni uzrok neuspešne terapije mastitisa. Može da se zaključi da je u stadu neophodno obavljati monitoring profi la rezistencije na antibiotike uz primenu efi kasnih antibiotika.

While the influence of water in Helicobacter pylori culturability and membrane integrity has been extensively studied, there are little data concerning the effect of this environment on virulence properties. Therefore, we studied the culturability of water-exposed H. pylori and determined whether there was any relation with the bacterium’s ability to adhere, produce functional components of pathogenicity and induce inflammation and alterations in apoptosis in an experimental model of human gastric epithelial cells. H. pylori partially retained the ability to adhere to epithelial cells even after complete loss of culturability. However, the microorganism is no longer effective in eliciting in vitro host cell inflammation and apoptosis, possibly due to the non-functionality of the cag type IV secretion system. These H. pylori-induced host cell responses, which are lost along with culturability, are known to increase epithelial cell turnover and, consequently, could have a deleterious effect on the initial H. pylori colonisation process. The fact that adhesion is maintained by H. pylori to the detriment of other factors involved in later infection stages appears to point to a modulation of the physiology of the pathogen after water exposure and might provide the microorganism with the necessary means to, at least transiently, colonise the human stomach., FCT (SFRH/BD/24579/2005) (to NMG)

Dryopteris crassirhizoma is traditionally used as an herbal remedy for various diseases, and has been identified in a previous study as a potential anti-caries agent. In this study, the effect of a methanol extract of D. crassirhizoma on the viability, growth and virulence properties of Streptococcus mutans, a cariogenic dental pathogen, was investigated. In addition, the phytochemical composition of the extract was analyzed. The extract showed bactericidal and bacteriostatic activity against oral bacteria (MIC and MBC of S. mutans: 62.5 and 250 μg/mL, respectively). At two times the MBC, the extract significantly eliminated S. mutans up to 99.9% after 1 h incubation. The extract also dose-dependently reduced growth rates of S. mutans at sub-MIC levels. Furthermore, at sub-MIC levels, virulence properties (acid production, acid tolerance, glucosyltransferase activity and sucrose-dependent adherence) of S. mutans were also inhibited in a dose-dependent manner. GC-MS analysis revealed the presence of mono and disaccharides (44.9%), fatty acids (12.3%) and sugar alcohols (6.8%) in the extract. These data indicate that the extract might be useful for the control of dental caries.

In this study, 154 Staphylococcus aureus isolates were detected from 1070 food samples (14.4%) collected from seven cities in Turkey. Antimicrobial susceptibility testing against 21 antibiotics was performed by agar disk diffusion method, and those isolates resistant to any antibiotic were further analyzed to determine minimum inhibitory concentration by E-test and polymerase chain reaction analysis of vanA and mecA genes. According to disk diffusion test results, a total of 139 strains were resistant to at least one tested antibiotic, with 39 (25.3%) strains being multidrug resistant (MDR) and the other 15 strains being susceptible to all antibiotics. Penicillin G, linezolid, erythromycin, and tetracycline took up 71.4%, 23.4%, 18.2%, and 15.6% of the tested strains, respectively. In addition, all of the strains were susceptible to vancomycin, oxacillin, cefoxitin, and imipenem. Only one strain (S158B) was resistant to both teicoplanin and cefazolin. On the other hand, the presence of vanA and mecA genes was not detected in the strains. Pulsed-field gel electrophoresis analysis was used to identify genetic-relatedness of the MDR strains. It is noteworthy that some strains from different sources showed 100% homology; however, some of MDR strains were found unrelated with 60% or less homology. The high diversity observed in pulsed-field gel electrophoresis results indicated the possible contamination of S. aureus from different sources and routes., The Scientific and Technological Research Council of Turkey (Turkey) (Project number:107T266)

Seaweeds known as "Mauro" are traditionally used fresh or to prepare omelettes in Sicily (Italy). Twenty samples sold in Catania between May 2005 and September 2007 were analyzed for Escherichia coli, Total Enterobacteria, Aeromonas spp., Pseudomonas spp., Vibrio spp., and Salmonella spp. Thirty Vibrio strains were examined for the presence of the virulence genes, toxR, toxRS, tl, tdh, and trh in the genomes of the isolates. Total Enterobacteria ranged between 2.23 and 6.85 log CFU/g, and in six samples, E. coli ranged between 0.70 and 2.74 log CFU/g. Aeromonas spp. was present in samples between 1.0 and 5.90 log CFU/g, while Pseudomonas spp. ranged between 2.70 and 7.27 log CFU/g. Vibrio spp. was present in 75% of samples at values between 1.30 and 4.60 log CFU/g. The most frequently isolated species was V. alginolyticus (76.66% of isolates), of which 82.60% were positive for toxR and the remaining 17.40% of strains were positive for toxRS. V. parahaemolyticus was identified in 13.33% of strains; all were positive for toxR and, in one case, for both toxR and toxRS. V. coralliitycus was isolated in 6.66% of strains (all positive for toxR), and one was identified as V. mimicus (positive for toxRS). The results of this study suggest that there is need for stringent quality control during harvesting and distribution of Mauro.

Seventeen Escherichia coli O111:H12 strains isolated from the feces of children with acute diarrhea were studied with regard to their adherence properties and other virulence characteristics. All strains showed an aggregative adherence pattern to HEp-2 cells and agglutinated bovine and sheep red cells in the presence of mannose. These strains did not have gene sequences homologous to the aggregative adherence fimbria I gene and did not react with any of the DNA probes used to detect other virulence genes in enteropathogens. With one exception, the O111:H12 strains did not induce fluid accumulation in the rabbit ileal loop assay, although 16 of the strains had the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene sequences. A 60-70 MDa plasmid was present in 16 of the strains studied. We conclude that the O111 :H12 serotype, one of the first E. coli identified in infantile diarrhea, belongs to the enteroaggregative E. coli category but the genes encoding its adherence phenotype are distinct from those previously described. UNIV São Paulo, INST CIENCIAS BIOMED, DEPT MICROBIOL, BR-05508900 São Paulo, BRAZIL UNIV São Paulo, FAC MED VET & ZOOTECNIA, DEPT PATOL, BR-05340900 São Paulo, BRAZIL Universidade Federal de São Paulo, ESCOLA PAULISTA MED, DEPT MICROBIOL IMMUNOL & PARASITOL, BR-04023062 São Paulo, BRAZIL Universidade Federal de São Paulo, ESCOLA PAULISTA MED, DEPT MICROBIOL IMMUNOL & PARASITOL, BR-04023062 São Paulo, BRAZIL Web of Science