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

Abstract

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.

Sequencing and Characterization of M. morganii Strain UM869: A Comprehensive Comparative Genomic Analysis of Virulence, Antibiotic Resistance, and Functional Pathways

“…The type-3 secretion system (T3SS) is a highly conserved virulence factor in disease-causing Gram-negative bacteria and is responsible for injecting bacterial effector proteins directly into the host cell cytoplasm [ 79 ]. Similarly, iron acquisition genes sitABCD mediate manganese–iron transfer and are essential for bacterial survival in iron-deficient environments [ 80 ]. The gene hlyA was also encoded in the UM869 genome, which is homologous to the α-hemolysin gene of E. coli .…”

The distinct transcriptome of virulence-associated phylogenetic group B2 Escherichia coli

“…Escherichia coli , which causes most UTIs and RUTIs ( 3 , 8 ), is a diverse species that can be divided into phylogenetic groups ( 9 , 10 ). Although strains from several phylogenetic groups are pathogenic ( 11 , 12 ), group B2 strains are more prevalent in UTIs and RUTIs ( 8 , 11 , 12 ), as well as in E. coli -caused neonatal meningitis ( 13 , 14 ), inflammatory bowel diseases (Crohn’s disease and ulcerative colitis) ( 15 – 17 ), and eye infections ( 18 ), are more often associated with colorectal cancer ( 19 ), and have more characteristics associated with multiple antibiotic resistance and extended spectrum β-lactamase production ( 20 ). Paradoxically, a phylogenetic evolutionary analysis found that group B2 strains have lost several environmental-adaptive genes, including genes for survival in extreme conditions of low pH, high temperature, and low osmolarity ( 21 ).…”