Bacteria recovered from endometritis and pyometra in the beef cow

Abstract

One hundred and one uteri from beef cows with pyometra were collected from a slaughterhouse. Samples of uterine exudate were cultured for aerobic, microaerophilic, and anaerobic bacteria, and also tested for Trichomonas spp. A section of uterine wall was fixed in 10% buffered formalin for light microscopic examination. The uteri were categorized into two groups based upon gross and histological observations: lochia/endometritis (63 uteri) and pyometra (37 uteri). The pyometra uteri were subcategories into early and late infections. A uterus in the pyometra group was bacterial culture negative, but grew fungus. One uterus harbored Trichomonas spp and was excluded from both categories of uteri. The majority of the bacterial isolates cultured from the lochia/endometritis group were strict and facultative aerobic bacteria with Escherichia coli as the most frequent isolate (25.6% of all isolates). Strict anaerobic bacteria were cultured at a rate of 36.8% of all isolates, the most common isolates being members of the Peptostreptococcus genera. Arcanobacterium pyogenes was cultured at a rate of 12.8% of all isolates (25.4% of lochia/endometritis uteri). Strict and facultative aerobic bacteria, and strict anaerobic bacteria were isolated from pyometra uteri at near equal recovery rates, 50.5% and 49.5% of all isolates respectively. The most common aerobic bacterial isolate was Arcanobacterium pyogenes, cultured at a rate of 22.9% of all isolates and present in 64.9% of uteri with pyometra. Gram positive species were the most prevalent of the strictly anaerobic bacterial isolates, accounting for 41% of all isolates, whereas Gram negative anaerobic bacterial isolates were uncommon (8.6% of anaerobic isolates). The histolytic examination revealed similar lesions amongst uteri in both categories. The difference between uteri with pyometra and uteri in the lochia/endometritis group was the degree, and not the type of infiltration and tissue damage observed. Bacteriologic data for pyometra in beef cows reflected the isolation patterns described in literature for dairy cows. However, in this study, the isolation rates of Gram positive strict anaerobic bacteria was higher than previously discussed in literature. It was hoped that relationships could be constructed between bacteriologic data, histolytic examination, and gross observation, but unfortunately, this was not possible.