Isolation of Morganella morganii from a domestic rabbit with bronchopneumonia

THE genus Morganella belongs to the family Enterobacteriaceae. This family also includes the genera Proteus and Providencia, which were formerly grouped within the so-called Proteaceae subfamily; these are important opportunistic pathogens capable of causing a wide variety of nosocomial infections in human beings (Williams and others 1983). Two subspecies of Morganella morganii have been described, M morganii subspecies morganii and M morganii subspecies sibonii (Jensen and others 1992). M morganii was previously classified as Proteus morganii; it was originally isolated from human infants with diarrhoea and was identified as a rare cause of lower respiratory tract infection (Lentnek and others 1984, Penner 1981). This short communication describes the first isolation of M morganii from a rabbit. A pet rabbit was presented for postmortem examination. The rabbit had come from a litter of 12 and was kept in a group with 10 adult rabbits (two males and eight females). Clinical signs had begun in two littermates eight to 10 days after weaning. These animals were treated with sulfamethazine (S-Mez 16%; Schering-Plough), but no positive effect was noted. Both animals died after two weeks of progressive anorexia and respiratory distress; abdominal dilation, depression and ataxia were also noted. When one of the two animals was presented to the private veterinarian, it was already dead. At postmortem examination, the rabbit was in good condition, but prominent congestion of the conchae with serohaemorrhagic fluid was found in the nasal cavity. The cranial and cardiac lobes of the lungs showed haemorrhagic consolidation, with congestion of the pleura. The liver was pale and the gastrointestinal tract was dilated. No further lesions were observed. Samples of lung and liver were collected for histopathological examination. For bacteriology, portions of the lungs were taken and inoculated on to an agar plate supplemented with 5 per cent sheep blood (CSB; Bio-rad) and a colistine aztreonam plate supplemented with 5 per cent sheep blood (CAP; Oxoid). A pure culture of semitransparent haemolytic colonies was detected on the blood agar plate. The isolate showed a negative result in the oxidase test (Oxoid). The strain was further tested with a BBL Crystal Enteric/Non-Fermenter identification system (Becton Dickinson); Kligler, indole, motility, lysine and ornithine tests were performed separately. The isolate was also investigated for its ability to ferment trehalose. Susceptibility was tested using the National Committee for Clinical Laboratory Standards (NCCLS) method, applying Rosco tablets (NeoSensitabs; Rosco). The results were interpreted using the Rosco manual with the NCCLS method. The antibiotics tested were apramycin, gentamicin, neomycin, nalidixic acid, enrofloxacin, choramphenicol, florfenicol, tetracycline, trimethoprim-sulphonamide and the β-lactam antibiotics ampicillin, amoxicillin-clavulanic acid, ceftiofur, ceftriaxone, cefepime, ceftazidime, aztreonam and imipenem. Histological examination of the lung tissue revealed the presence of neutrophils in the alveolar spaces interlaced with serofibrinous fluid, macrophages, and desquamated and necrotic epithelial cells. The alveolar septa were thickened due to congestion and a mild infiltration of mixed inflamVeterinary Record (2007) 161, 530-531