Escherichia fergusonii Associated with Pneumonia in a Beef Cow

An adult Angus cow developed hyperthermia, prostration, and respiratory distress, dying 36 hours after the onset of clinical signs. The main finding during postmortem examination was a severe focally extensive pneumonia. Icterus and a chronic mastitis were also noticed. Histologic examination of the lungs detected fibrinonecrotic pneumonia, with large number of oat cells and intralesional Gram-negative bacterial colonies. Samples from lung lesions were collected, and a pure growth of Escherichia fergusonii was obtained. E. fergusonii is a member of Enterobacteriaceae, related to Escherichia coli and Salmonella sp. In veterinary medicine, E. fergusonii has been reported in calves and sheep with clinical cases suggestive of salmonellosis; in a horse and a goat with enteritis and septicemia; and in ostriches with fibrinonecrotic typhlitis. To our knowledge, this report represents the first description of E. fergusonii associated with an acute pneumonia in cattle. 1. Introduction Escherichia fergusonii was described as a new species of the genus Escherichia, family Enterobacteriaceae in 1985 [1]. It is closely related to E. coli, with whom it shares many of its biochemical properties and resembles the genus Salmonella in the lack of lactose breakdown activity. When first identified, the clinical significance of this organism was unclear. First isolate suggesting that this organism was a pathogen was from a human patient with pancreatic carcinoma and cholangiosepsis, in Switzerland. The organism was detected in the blood, gallbladder fluid, feces, and a superficial abdominal wound [2]. In the veterinary literature, E. fergusonii has been associated with a clinical case of acute enteritis, septicemia, and death of an adult horse from Germany [3]. E. fergusonii was also isolated from intestine, lung, liver, and kidney from a goat with a history of chronic diarrhea and emaciation, in Canada [4]. In cattle, E. fergusonii has been isolated from animals with diarrhea, clinically suggestive of salmonellosis [5]. Birds seem to be also susceptible to E. fergusonii infections; this bacterium was isolated in pure growth from lesions in ostriches with severe hemorrhagic diarrhea and fibrinonecrotic typhlitis [6]. Common pulmonary bacterial pathogens in cattle include Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Mycoplasma bovis, and Trueperella (Arcanobacterium) pyogenes. Young animals are more prone to develop pneumonias caused by one or more of these agents; however, adult animals are also susceptible, particularly when immunocompromised. In this