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Effect of trimethoprim/sulphamethoxazole and hyperbaric oxygen on experimental Spiroplasma mirum encephalitis
F O Bastian1, R A Jennings, C J Hoff
1Department of Pathology, University of South Alabama, College of Medicine, Mobile 36617.
Abstract:
This study was undertaken to determine the susceptibility of experimentally induced Spiroplasma mirum infection in the rat to trimethoprim/sulfamethoxazole (TMP/SMX) in combination with hyperbaric oxygen (HBO). One-day-old Fisher 344 rats were intracerebrally inoculated with the GT-48 strain of S. mirum and were exposed to regimens employed combined antibiotic and HBO treatments. The exclusive use of TMP/SMX produced a significant reduction in mortality (P less than 0.0001) and an absence of clinical signs of infection. HBO in combination with TMP/SMX showed similar effect on mortality and no evident clinical disease. The addition of HBO did result in a significant decrease in spiroplasma brain titres but was no more effective in preventing the spiroplasma-induced fatal microcystic encephalopathy than when the antibiotics were used alone. The exclusive use of HBO produced a catastrophic mortality rate in the spiroplasma-infected rats, which is contrary to the effect of HBO on conventional bacterial infections.
Insights
Trimethoprim/sulfamethoxazole (TMP/SMX) effectively treated Spiroplasma mirum infections in rats, reducing mortality. Adding hyperbaric oxygen (HBO) did not improve outcomes and showed negative effects when used alone.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Spiroplasma mirum is a pathogen that can cause severe infections.
- The efficacy of trimethoprim/sulfamethoxazole (TMP/SMX) and hyperbaric oxygen (HBO) against S. mirum is not well-established.
- Experimental models are crucial for evaluating treatment strategies.
Purpose of the Study:
- To assess the susceptibility of experimental Spiroplasma mirum infection in rats to TMP/SMX.
- To evaluate the combined effect of TMP/SMX and HBO on S. mirum infection.
- To determine the impact of HBO alone on S. mirum-infected rats.
Main Methods:
- One-day-old Fisher 344 rats were intracerebrally inoculated with S. mirum.
- Rats were treated with TMP/SMX alone, or in combination with HBO.
- Mortality rates, clinical signs, and brain S. mirum titres were assessed.
Main Results:
- TMP/SMX significantly reduced mortality (P < 0.0001) and prevented clinical signs.
- Combined TMP/SMX and HBO showed similar efficacy to TMP/SMX alone.
- HBO alone resulted in catastrophic mortality, contrasting its effects on bacterial infections.
- HBO addition decreased brain S. mirum titres but did not prevent fatal encephalopathy.
Conclusions:
- TMP/SMX is an effective treatment for experimental S. mirum infections in rats.
- Hyperbaric oxygen does not enhance the efficacy of TMP/SMX and is detrimental when used alone.
- Further research is needed to understand HBO's paradoxical effect in this spiroplasma model.