Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli

Abstract

Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide. Particular strains cause persistent IMI, leading to recurrent mastitis. Virulence factors of mammary pathogenic E. coli (MPEC) involved pathogenesis of mastitis as well as those differentiating strains causing acute or persistent mastitis are largely unknown. This study aimed to identify virulence markers in MPEC through whole genome and phenome comparative analysis. MPEC strains causing acute (VL2874 and P4) or persistent (VL2732) mastitis were compared to an environmental strain (K71) and to the genomes of strains representing different E. coli pathotypes. Intra-mammary challenge in mice confirmed experimentally that the strains studied here have different pathogenic potential, and that the environmental strain K71 is non-pathogenic in the mammary gland. Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes. Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism. Features associated with cytotoxicity or intra-cellular survival were found specifically in the genomes of strains from severe and acute (VL2874) or persistent (VL2732) mastitis, respectively. MPEC genomes were relatively similar to strain K-12, which was subsequently shown here to be possibly pathogenic in the mammary gland. Phenome analysis showed that the persistent MPEC was the most versatile in terms of nutrients metabolized and acute MPEC the least. Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism. This study reveals virulence factors and phenotypic characteristics of MPEC that may play a role in pathogenesis of E. coli mastitis.

No evidence for a bovine mastitisEscherichia colipathotype

“…So far, depending on the study, no or only one bovine commensal E. coli isolate has been included in these corresponding analyses [25][26][27][28].…”

“…The flexible genome consists largely of mobile genetic elements (MGEs), including plasmids, genomic islands (GI), and phages, which facilitate horizontal gene transfer (HGT) and are the driving forces for microbial diversity, evolution, and adaptation potential [21].Despite the proposal of a mammary pathogenic E. coli (MPEC) pathotype [3] and extensive research, no common genetic traits or VFs have been identified for E. coli mastitis isolates, so far [11,[22][23][24]. Recently, several publications analyzed E. coli genomes from intramammary infections, thereby expanding the method spectrum by comparative genomics approaches [25][26][27][28]. All of these studies identified various MPEC genome regions and genes with different 5 of 54 60 65 70 75 80 specificity criteria and significance, many of which are not considered to be classical VFs (or even encode for unknown hypothetical functions), but also genes coding for a type VI secretion system (T6SS), LPS biosynthesis, biofilm association, metabolic functions, and the ferric iron(III)-dicitrate (Fec) uptake system.…”

“…However, the studies could mostly not agree upon a common set of putative VFs, except for the Fec siderophore system. Also, these studies suffer from small genome sample size constraints, lack of phylogenetic diversity, and/or did not include commensal bovine E. coli comparator strains of suitable phylogenetic and genotypic diversity.So far, depending on the study, no or only one bovine commensal E. coli isolate has been included in these corresponding analyses [25][26][27][28].We wanted to advance upon the previous studies by analyzing a strain panel of phylogenetic and genomic diversity comparable to E. coli from the bovine habitat, especially by including fecal commensal isolates from udder-healthy cows. This enables our main goal, to characterize genetic traits which define mastitis-associated E. coli (MAEC) in comparison to non-pathogenic commensals, while keeping track of their phylogenetic background.…”

Molecular characterization of antibiotic resistant Escherichia coli isolated from bovine mastitis in Michoacán, México

“…Sin embargo, se ha observado gran diversidad tanto genética como en los factores de virulencia entre esas bacterias (6,7) . De estos últimos factores, muchos son comunes con los patotipos de humanos e incluyen toxinas, adhesinas, producción de cápsula, la habilidad para resistir el complemento sérico y sistemas de adquisición de hierro (7)(8)(9) .…”

Molecular Studies on E.Coli Isolate from Milk of Mastatic Cattle with Special Reference to Associated Biochemical Changes in Kaliobea Governorate

“…The most important causitave environmental mastitis pathogen is E.coli [2]. Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide [3]. Particular strains cause persistent IMI, leading to recurrent mastitis.…”