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A shift from acute to chronic spontaneous pyelonephritis in male MM mice associated with a change in the causal
1AFRC & MRC Neuropathogenesis Unit, Edinburgh, United Kingdom.
Abstract:
Proteus mirabilis was the predominant cause of acute diabetes-associated pyelonephritis occurring spontaneously in male MM mice until they were segregated in a new environment. Thereafter Pasteurella pneumotropica and Streptococcus faecalis emerged collectively as the most common causal organisms, the pyelonephritis became more chronic and Proteus mirabilis isolates from faeces and urine produced atypical non-swarming colonies on blood agar plates. This did not account for the reduced pathogenicity of Proteus mirabilis; when MM males were returned to the original environment the pyelonephritis again became acute but was associated with the atypical type of Proteus mirabilis although the normal type was abundant in the environment. The MM mice were Caesarean-derived and cross-fostered shortly before their transfer to the second environment, which probably accounts for their changed microbial status, but the reason for the emergence of the atypical type of Proteus mirabilis is not understood. The acute nature of the male MM pyelonephritis when caused by Proteus mirabilis parallels the situation described in other animals and humans.
Insights
Environmental changes altered the cause of pyelonephritis in male mice. Proteus mirabilis initially caused acute infections, but later, atypical strains emerged, even when normal strains were present.
Area of Science:
- Microbiology
- Immunology
- Animal Health
Background:
- Proteus mirabilis is a common cause of pyelonephritis in male mice.
- Environmental changes can influence microbial populations and disease presentation.
Purpose of the Study:
- To investigate the etiological agents and characteristics of pyelonephritis in male MM mice under different environmental conditions.
- To understand the shift in microbial dominance and the emergence of atypical bacterial strains.
Main Methods:
- Monitoring of spontaneous pyelonephritis in male MM mice housed in distinct environments.
- Microbiological culture and characterization of causative agents from urine and feces.
- Observation of colony morphology on blood agar plates.
Main Results:
- Proteus mirabilis was the primary cause of acute pyelonephritis initially.
- Segregation into a new environment led to Pasteurella pneumotropica and Streptococcus faecalis becoming dominant, with chronic pyelonephritis.
- Atypical, non-swarming Proteus mirabilis colonies emerged, associated with acute pyelonephritis upon return to the original environment, despite the presence of normal strains.
Conclusions:
- Environmental shifts significantly impact the microbial etiology and chronicity of pyelonephritis in male MM mice.
- The emergence of atypical Proteus mirabilis is not fully understood but influences disease presentation.
- The acute pyelonephritis observed in male MM mice caused by Proteus mirabilis mirrors findings in other animal models and humans.