Indigenous microfloras and resistance to bacterial infection in mice with experimentally induced diabetes: a possible animal model for opportunistic infection.

Persistent diabetes was induced in male Slc:ddY mice by a single intraperitoneal injection of 200 mg/kg streptozotocin (STZ). In these mice, the numbers of aerobic gram-negative bacilli, staphylococci (including micrococci), and streptococci increased, while those of other bacteria were almost unchanged in both oral and caecal floras. The mice were vulnerable to oral infection of Salmonella enteritidis, intranasal infection of Klebsiella pneumoniae and Serratia marcescens, and contact infection with mice infected with S. enteritidis and K. pneumoniae. These findings suggest that STZ-treated mice might be a useful model for investigating opportunistic infection.