Evaluation of the Pathogenic Potential of Escherichia coli Strains Isolated from Eye Infections.

While primarily Gram-positive bacteria cause bacterial eye infections, several Gram-negative species also pose eye health risks. Currently, few studies have tried to understand the pathogenic mechanisms involved in E. coli eye infections. Therefore, this study aimed to establish the pathogenic potential of E. coli strains isolated from eye infections. Twenty-two strains isolated between 2005 and 2019 from patients with keratitis or conjunctivitis were included and submitted to traditional polymerase chain reactions (PCR) to define their virulence profile, phylogeny, clonal relationship, and sequence type (ST). Phenotypic assays were employed to determine hemolytic activity, antimicrobial susceptibility, and adhesion to human primary corneal epithelial cells (PCS-700-010). The phylogenetic results indicated that groups B2 and ST131 were the most frequent. Twenty-five virulence genes were found among our strains, with ecp, sitA, fimA, and fyuA being the most prevalent. Two strains presented a hemolytic phenotype, and resistance to ciprofloxacin and ertapenem was found in six strains and one strain, respectively. Regarding adherence, all but one strains adhered in vitro to corneal cells. Our results indicate significant genetic and virulence variation among ocular strains and point to an ocular pathogenic potential related to multiple virulence mechanisms.

Unveiling the Virulent Genotype and Unusual Biochemical Behavior of Escherichia coli ST59.

Extraintestinal pathogenic Escherichia coli (ExPEC) is a leading cause of human and animal infections worldwide. The utilization of selective and differential media to facilitate the isolation and identification of E. coli from complex samples, such as water, food, sediment, and gut tissue, is common in epidemiological studies. During a surveillance study, we identified an E. coli strain isolated from human blood culture that displayed atypical light cream-colored colonies in chromogenic agar and was unable to produce ß-glucuronidase and ß-galactosidase in biochemical tests. Genomic analysis showed that the strain belongs to sequence type 59 (ST59) and phylogroup F. The evaluation in silico of 104 available sequenced lineages of ST59 complex showed that most of them belong to serotype O1:K1:H7, are ß-glucuronidase negative, and harbor a virulent genotype associated with the presence of important virulence markers such as pap, kpsE, chuA, fyuA, and yfcV. Most of them were isolated from extraintestinal human infections in diverse countries worldwide and could be clustered/subgrouped based on papAF allele analysis. Considering that all analyzed strains harbor a virulent genotype and most do not exhibit biochemical behavior typical of E. coli, we report that they could be misclassified or underestimated, especially in epidemiological studies where the screening criteria rely only on typical biochemical phenotypes, as happens when chromogenic media are used. IMPORTANCE The use of selective and differential media guides presumptive bacterial identification based on specific metabolic traits that are specific to each bacterial species. When a bacterial specimen displays an unusual phenotype in these media, this characteristic may lead to bacterial misidentification or a significant delay in its identification, putting a patient at risk depending on the infection type. In the present work, we describe a virulent E. coli sequence type (ST59) that does not produce beta-glucuronidase (GUS negative), production of which is the metabolic trait widely used for E. coli presumptive identification in diverse differential media. The recognition of this unusual metabolic trait may help in the proper identification of ST59 isolates, the identification of their reservoir, and the evaluation of the frequency of these pathogens in places where automatic identification methods are not available.

Diversity of Hybrid- and Hetero-Pathogenic Escherichia coli and Their Potential Implication in More Severe Diseases.

Although extraintestinal pathogenic Escherichia coli (ExPEC) are designated by their isolation site and grouped based on the type of host and the disease they cause, most diarrheagenic E. coli (DEC) are subdivided into several pathotypes based on the presence of specific virulence traits directly related to disease development. This scenario of a well-categorized E. coli collapsed after the German outbreak of 2011, caused by one strain bearing the virulence factors of two different DEC pathotypes (enteroaggregative E. coli and Shiga toxin-producing E. coli). Since the outbreak, many studies have shown that this phenomenon is more frequent than previously realized. Therefore, the terms hybrid- and hetero-pathogenic E. coli have been coined to describe new combinations of virulence factors among the classic E. coli pathotypes. In this review, we provide an overview of these classifications and highlight the E. coli genomic plasticity that results in some mixed E. coli pathotypes displaying novel pathogenic strategies, which lead to a new symptomatology related to E. coli diseases. In addition, as the capacity for genome interrogation has grown in the last few years, it is clear that genes encoding some virulence factors, such as Shiga toxin, are found among different E. coli pathotypes to which they have not traditionally been associated, perhaps foreshowing their emergence in new and severe outbreaks caused by such hybrid strains. Therefore, further studies regarding hetero-pathogenic and hybrid-pathogenic E. coli isolates are necessary to better understand and control the spread of these pathogens.

Draft Whole-Genome Sequence of a Uropathogenic Escherichia coli Strain Carrying the eae Gene.

Uropathogenic Escherichia coli (UPEC) strains are responsible for most cases of urinary tract infections worldwide. We present the draft whole-genome sequence of the UPEC 252 strain, which carries the eae gene that encodes the intimin adhesin. Intimin promotes intimate adherence of enteropathogenic E. coli and enterohemorrhagic E. coli to intestinal cells.

Phenotypic characterization and virulence-related properties of Escherichia albertii strains isolated from children with diarrhea in Brazil.

Escherichia albertii are emerging enteropathogens, whose identification is difficult, as they share biochemical characteristics and some virulence-related genes with diarrheagenic Escherichia coli (DEC). Studies on phylogeny, phenotypic characteristics and potential virulence factors of human E. albertii strains are scarce. In this study, we identified by multiplex PCR five E. albertii among 106 strains isolated from diarrheic children in São Paulo, Brazil, which were previously classified as atypical enteropathogenic E. coli. All strains were investigated regarding their phylogeny, biochemical properties, virulence-related properties, antimicrobial resistance and presence of putative virulence-related genes. All strains belonged to different E. albertii lineages and adhered to and produced attaching and effacing lesions on HeLa cells. Three strains invaded Caco-2 cells, but did not persist intracellularly, and three formed biofilms on polystyrene surfaces. All strains were resistant to few antibiotics and only one carried a self-transmissible resistance plasmid. Finally, among 38 DEC and 18 extraintestinal pathogenic E. coli (ExPEC) virulence-related genes searched, six and three were detected, respectively, with paa and cdtB being found in all strains. Despite the limited number of strains, this study provided additional knowledge on human E. albertii virulence potential, showing that they share important virulence factors with DEC and ExPEC.

Draft whole-genome sequence of a uropathogenic Escherichia coli strain carrying the eae gene

Uropathogenic Escherichia coli (UPEC) strains are responsible for most cases of urinary tract infections worldwide. We present the draft whole-genome sequence of the UPEC 252 strain, which carries the eae gene that encodes the intimin adhesin. Intimin promotes intimate adherence of enteropathogenic E. coli and enterohemorrhagic E. coli to intestinal cells.

Draft whole-genome sequence of a uropathogenic Escherichia coli strain carrying the eae gene

Uropathogenic Escherichia coli (UPEC) strains are responsible for most cases of urinary tract infections worldwide. We present the draft whole-genome sequence of the UPEC 252 strain, which carries the eae gene that encodes the intimin adhesin. Intimin promotes intimate adherence of enteropathogenic E. coli and enterohemorrhagic E. coli to intestinal cells.

A virulência de Escherichia coli patogênica extra-intestinal (ExPEC) em relação à idade e ao sexo do hospedeiro / La virulencia de Escherichia coli (ExPEC) patogénica intraintestinal en relación a la edad y al sexo del hospedero / Extraintestinal Pathogenic Eschericia coli (ExPEC) virulence regarding host age and sex

A Escherichia coli é, entre os bacilos Gram-negativos, o principal agente etiológico de infecções da corrente sanguínea, seja comunitárias seja as nosocomiais. Uma vez que são poucos os trabalhos que pesquisaram a virulência de amostras de E. coli isoladas de bacteremia no Brasil, este trabalho teve por objetivo investigar os fatores de virulência frequentes em amostras isoladas de seres humanos hospitalizados bem como a origem filogenética destas amostras, relacionando essas características bacterianas com características do hospedeiro como sexo e idade. A pesquisa da origem filogenética das amostras foi realizada utilizando-se a técnica da PCR e a pesquisa de fatores de virulência por hibridação de colônias com sondas radioativas. O resultado obtido com a pesquisa de 20 fatores de virulência demonstrou que os fatores relacionados à fimbria tipo 1, ao sistema yersiniabactina de aquisição de ferro e à produção de cápsula, foram os mais frequentes nas amostras estudadas. Além disso, a grande maioria das amostras foi classificada nos grupos filogenéticos B2 e D. Em relação às características do hospedeiro, foi possível estabelecer uma relação positiva entre amostras mais virulentas e infecções em pacientes do sexo feminino. Contudo, não houve diferença na virulência das amostras em relação à idade do hospedeiro. Estes dados sugerem que as amostras que causam infecções extra-intestinais em pacientes do sexo feminino são, em geral, mais virulentas do que aquelas que causam infecções nos pacientes do sexo masculino. Por outro lado, a idade não parece ter correlação com a virulência da amostra infectante.

Escherichia Coli es, entre los bacilos gram negativos, el agente etiológico principal de infecciones de la cadena sanguínea, sean comunitarias o nosocomiales. Como son pocos los trabajos que han estudiado la virulencia de muestras de Escherichia Coli aisladas de bacteremia en Brasil, este trabajo tiene el objetivo de investigar los factores frecuentes de virulencia en muestras aisladas de seres humanos hospitalizados así bien el del filogenética de estas muestras, relacionando estas características bacterianas con las características sexo y edad del hospedero. La investigación del origen filogenética de las muestras fue realizada utilizando la técnica de reacción en cadena de polimerasa y la investigación de factores de factores de virulencia mediante hibridación de colonias con sondas radioactivas. El resultado conseguido con la investigación de 20 factores de virulencia demostró que los factores relacionados a las fimbrias tipo 1, al sistema yersiniabactina de adquisición del hierro y a la producción de cápsula fueran los más frecuentes en las muestras estudiadas. Por otra parte, se clasificaron a la gran mayoría de las muestras en los grupos filogenéticos B2 y D. En lo referente a las características del hospedero, fue posible establecer una relación positiva entre muestras más virulentas e infecciones en pacientes del sexo femenino. Sin embargo, no hubo diferencia en la virulencia de las muestras en lo referente a la edad del hospedero. Estos datos sugieren que las muestras que causan las infecciones extraintestinales en pacientes del sexo femenino son generalmente más virulentas que las que causan infecciones en pacientes del sexo masculino. Por otra parte, la edad no parece tener correlación con la virulencia de la muestra infectante.

E. coli is the Gram-negative rod most important cause of bacteremia both in the community and in the hospital environment. Since the reports on virulence of E. coli isolated from the bloodstream are rare in Brazil, this work aimed to investigate isolates from hospitalized patients in regard to the frequency of their virulence factors, and phylogeny, as well as their relationship with the sex and age of the patients. The analysis of phylogenetic relationship was done by PCR, and the search for virulence factors by colony hybridization. Most of the strains were classified in phylogenetic groups B2 and D. Among 20 virulence traits searched, the most frequent were related to Type1 fimbriae, yersiniabactin iron acquisition system, and capsule. The most virulent strains were found in the female gender, while age seemed not to have any connection with the virulence of the isolates. These data suggest that E. coli strains causing bacteremia in female patients are more virulent than those able to cause the same infection in man. The same is not seen in regard to the age of the patients.