Short communication: Investigation of extra-intestinal pathogenic Escherichia coli virulence genes, bacterial motility, and multidrug resistance pattern of strains isolated from dairy cows with different severity scores of clinical mastitis

Abstract

Escherichia coli is a major pathogen involved in the etiology of environmentally derived bovine mastitis and is characterized by a variety of virulence factors (VF). Mammary infections with E. coli have shown a wide range of clinical signs, causing changes in milk (score 1, or mild), abnormal appearance of milk and udder inflammation (score 2, or moderate), and abnormalities in milk, udder inflammation, and systemic signs of illness (score 3, or severe). Nevertheless, to date, the profile of the genes related to the virulence of the pathogen in mammary infections and the severity scores of cases have not been thoroughly elucidated. Therefore, a panel of 18 virulence-encoding genes associated with extra-enteric pathogenicity of E. coli (ExPEC) were investigated in addition to in vitro swimming and swarming motility profiles and antimicrobial susceptibility/ resistance patterns among 114 E. coli strains isolated from cows with clinical mastitis and different severity scores. Of 114 clinical cases, 39.5, 54.4, and 6.1% were mild, moderate, and severe, respectively. The main genes related to VF harbored by isolates were adhesins (fimH 100%; ecpA 64.0%, fimA 31.6%), serum resistance (traT 81.6%; ompT 35.1%), siderophores (irp2 9.6%), and hemolysin (hlyA 7%). Among the isolates studied, 99.1% showed in vitro resistance to bacitracin and cloxacillin, and 98.2% to lincosamin. Of the total isolates, 98.2% were considered multidrug resistant based on the multiple antimicrobial resistance index. No significant difference was observed between mean swimming (13.8 mm) and swarming (13.5 mm) motility, as well as severity scores of clinical mastitis and the ExPEC genes studied. The isolation of strains resistant to various antimicrobials, even though tested only in vitro, highlights the importance of rational use of antimicrobials for mastitis treatment. The high prevalence of the genes related to serum resistance (traT and ompT) and adhesion (ecpA) of the pathogen, in addition to main associations between the genes fimH, ecpA, and traT among cows with severity scores of 1 (15%) and 2 (22.6%), indicates that the genes traT, ecpA, and ompT could be further studied as biomarkers of ExPEC for clinical intramammary infections. In addition, the Ex-PEC genes ompT (protectin), ibe10 (invasin), and ecpA (adhesin) were investigated for the first time among cows with mastitis, where scores of clinical severity were assessed. Results of this study contribute to the characterization of virulence mechanisms and antimicrobial resistance profile of ExPEC variants that affect dairy cows with different scores of clinical mastitis.

Towards discrimination of mammary pathogenic Escherichia coli (MPEC) in cattle based on possession of different iron acquisition systems

“…15.9% and chuA= 8.3%) are situated in the ranges. Nevertheless, presence of fyuA (15.3%) and iroN (14%) among our isolates were higher than previous records (2.5% and 3.5%, respectively) (12,14). Unfortunately, our results of iron acquisition genotypes are incomparable with most of the previous studies, as no focus on iron uptake systems can be observed among them.…”

“…Moreover, the data about chuA can be extracted from the results of phylogenetic grouping conducted based on the Clermont’s procedures. Prevalence of the genes iucD, irp2 and chuA are recorded in ranges of 0-16.7% (12, 13), 2.5-26.4% (13, 14) and 5.7-35.6% (15, 16), respectively by other researchers, and our findings ( iucD = 10.8%, irp2 = 15.9% and chuA = 8.3%) are situated in the ranges. Nevertheless, presence of fyuA (15.3%) and iroN (14%) among our isolates were higher than previous records (2.5% and 3.5%, respectively) (12, 14).…”

“…Prevalence of the genes iucD, irp2 and chuA are recorded in ranges of 0-16.7% (12, 13), 2.5-26.4% (13, 14) and 5.7-35.6% (15, 16), respectively by other researchers, and our findings ( iucD = 10.8%, irp2 = 15.9% and chuA = 8.3%) are situated in the ranges. Nevertheless, presence of fyuA (15.3%) and iroN (14%) among our isolates were higher than previous records (2.5% and 3.5%, respectively) (12, 14). Unfortunately, our results of iron acquisition genotypes are incomparable with most of the previous studies, as no focus on iron uptake systems can be observed among them.…”

Virulence Determinants and Plasmid-Mediated Colistin Resistance mcr Genes in Gram-Negative Bacteria Isolated From Bovine Milk

“…The virulome of our colistin-resistant isolates was screened in each species. Many of the identified virulence genes in our study were required for bacterial survival and had a role in causing mastitis ( Tartor and El-Naenaeey, 2016 ; Gao et al., 2019 ; Guerra et al., 2020 ). This in turn raises the alarm that most of the colistin-resistant Gram-negative isolates are highly pathogenic.…”

Bacteriophage Cocktails Protect Dairy Cows Against Mastitis Caused By Drug Resistant Escherichia coli Infection

“…Recently, E. coli has become the most important pathogen inducing cow mastitis, mainly causing high fever or lower milk production, even resulting in lethal consequences (Fazel et al, 2019;Guerra et al, 2020). Also, E. coli is an important antibiotic-resistant priority pathogen and can disseminate resistant genes in a process known as 'horizontal transfer' into other microbial communities (Jianying et al, 2008).…”