Salmonella enterica Infection

Syrian hamsters are very susceptible to bacteremic S. enterica infections, but outbreaks in contemporary laboratory animal colonies are now rare. Unfortunately, Salmonella infections of pet rodents, including hamsters, have resulted in multiple zoonotic infections with mul­tidrug-resistant isolates.

FIG. 3.17. Ultrastructural section of ileal mucosa from a hamster infected with Lawsonia Intracellularis. Note Lawsonia organisms within the apical cytoplasm of enterocytes.

Pathology

Explosive outbreaks of salmonellosis are characterized by depression, ruffled hair coat, anorexia, dyspnea, and high mortality. At necropsy, there may be multifocal, pinpoint-size, pale areas in the liver, with patchy pul­monary hemorrhage and reddened hilar lymph nodes (Fig. 3.18). Microscopic changes in the lung are charac­terized by multifocal interstitial pneumonitis, with intra- alveolar hemorrhage. There may be a septic thrombo­phlebitis in pulmonary veins and venules, with thrombi containing leukocytes, and erosion of venous walls (Fig. 3.19). Focal splenic necrosis and focal necrotizing hepatitis, with leukocytic infiltration and venous throm­bosis, are typical lesions. Embolic glomerular lesions and focal splenitis may also occur.

FIG. 3.18. Multifocal pulmonary hemorrhages in hamsters with acute Salmonella septicemia. (Courtesy A. Wuenschmann.)

FIG. 3.19. Pulmonary venous thrombosis in a hamster with acute salmonellosis.

Diagnosis

In acute salmonellosis, the organism can usually be read­ily recovered from blood, lung, and other viscera. Differ­ential diagnoses include Tyzzer's disease, pathogenic E. coli infections, and other acute bacteremic infections. Subclinical carriers may also be common among ham­sters, requiring surveillance of feces by culture or PCR.