Prevalence of virulence factors in Escherichia coli strains isolated from the genital tract of healthy cows

Virulence factors and phylogenetic group profile of uterine Escherichia coli in early postpartum of high-producing dairy cows

Escherichia coli is the most common contaminant of the bovine uterus in the first few weeks postpartum, and one of the most important pathogens involved in uterine infections. This bacterium is characterised by diverse virulence factors (VF); however, the profile of E. coli VF in physiologic postpartum uterine contamination is not well established. Therefore, the present study aimed to investigate the prevalence of intrauterine bacteria, a set of virulence factors and phylogroups of E. coli isolates, leukogram and uterine cytology in 75 Holstein cows at 24 h (Sampling time 1) and 14 days (Sampling time 2) postpartum. Escherichia coli, α-haemolytic Streptococcus, Trueperella pyogenes, and Pasteurella multocida were the most common microorganisms isolated in pure culture, whereas E. coli and Clostridium perfringens Type A, E. coli and α-haemolytic Streptococcus, and E. coli and Proteus mirabilis were the most frequent microorganisms in mixed colonies at both studied sampling times. In the 59 E. coli isolates after 24 h (n = 35) and 14 days (n = 24) postpartum, the genes detected for VF were fimH, iucD/aer, kps, hlyA, usp, vt1 and vt2. Most E. coli strains detected in both moments of study belonged to Commensal phylogenetic groups A and B1, whereas Pathogenic groups D and B2 were identified at 24 h and 14 days postpartum respectively. All cows presented suitable immune response against the presence of bacteria in uterine lumen, observed by leukocytosis, neutrophilia, lymphocytosis and monocytosis at leukogram and a high number of polymorphonuclear leukocytes in uterine cytology, in both studied moments. Thus, a complex diversity of aerobic and anaerobic bacteria is involved in uterine contamination in the early postpartum of cows, besides the predominance of E. coli. Moreover, the genes fimH, iucD/aer, hlyA, kps, usp, vt1 and vt2 play a key role in the virulence of E. coli in this period.

Characterization of buffalo interleukin 8 (IL-8) and its expression in endometritis

River buffalo (Bubalus bubalis bubalis) with a population over 135 million heads is an important livestock. Interleukin 8 (IL-8) is a member of the chemokine family and is an important chemoattractant for neutrophils associated with a wide variety of inflammatory diseases such as endometritis. Tissue samples from the mammary gland, uterus and ovary were obtained from river buffalo (Mediterranean type) with and without endometritis. Bacteriological examination showed the presence of both gram positive and negative in all buffalo with endometritis. RNA extraction and complementary DNA (cDNA) synthesis were conducted from all tissues. Specific primer for IL8 full coding regions was designed using known cDNA sequences of Bubalus bubalis, Genbank accession number AY952930.1. IL-8 gene expression was investigated in buffalo tissues. Expression of IL-8 in buffalo with endometritis was found to increase significantly over buffalo without endometritis only in the uterus (P = 0.0159). PCR products from uterus tissues (target organs) of buffalo with and without endometritis, were purified and sequenced. No polymorphic sites were detected in the investigated samples. IL-8 cDNA nucleotide sequences of buffalo with and without endometritis were 100% identical (accession number JX413057). Buffalo IL8 cDNAs were compared with corresponding sequences of member of subfamily Bovinae (buffalo and cattle) and subfamily Caprinae (sheep and goat). IL-8 species specific differences were identified.