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Comparison of methods for detection of Mycoplasma pulmonis in experimentally and naturally infected rats
Abstract:
Isolation, indirect immunofluorescence, an enzyme-linked immunosorbent assay (ELISA), and histopathological examination of tissues for characteristic lesions were evaluated for their efficiency in detecting Mycoplasma pulmonis infection in rats. Whereas all of the methods were efficient in naturally infected Sprague-Dawley rats, none of the methods consistently detected infection in F344 rats experimentally infected with low doses of the organism. In the experimental infections, however, the success rate of any method was directly related (P less than 0.05) to increasing inoculum dose and time postinoculation. Collectively, the data indicated that isolation of M. pulmonis was the most efficient single detection method and the nasopharyngeal duct was the best single site to culture, although sampling of multiple sites within the respiratory tract increased the rate of isolating the organism. The ELISA was understandably the least sensitive method in the low-dose, experimentally infected rats because of the time required for development of a detectable serum antibody response. Although each of the four methods identified a high percentage of naturally infected rats, the ELISA was the most efficient method in these animals as it was uniformly positive. The use of combinations of methods was found to increase the rate of detection of M. pulmonis infection in both experimentally and naturally infected rats.
Insights
Detecting Mycoplasma pulmonis infection in rats requires careful method selection. While isolation is best for experimental cases, enzyme-linked immunosorbent assay (ELISA) excels in naturally infected animals, with combined methods improving detection rates.
Area of Science:
- Veterinary Microbiology
- Infectious Disease Diagnostics
- Rodent Health
Background:
- Mycoplasma pulmonis is a common respiratory pathogen in laboratory rats.
- Accurate detection is crucial for research integrity and animal welfare.
- Various diagnostic methods exist, but their efficacy can vary depending on infection type and host factors.
Purpose of the Study:
- To evaluate and compare the diagnostic efficiency of four methods for Mycoplasma pulmonis detection in rats.
- To determine the optimal detection strategy for both experimentally induced and naturally occurring infections.
- To assess the influence of inoculum dose and time post-inoculation on diagnostic success.
Main Methods:
- Evaluated isolation, indirect immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and histopathology.
- Used Sprague-Dawley rats with natural infections and F344 rats with experimental low-dose infections.
- Assessed detection rates based on inoculum dose and time post-inoculation.
Main Results:
- All methods were efficient in naturally infected rats; ELISA was uniformly positive.
- No single method consistently detected low-dose experimental infections.
- Isolation of M. pulmonis was the most efficient single method, with the nasopharyngeal duct being the best culture site.
- Detection success correlated with increasing inoculum dose and time post-inoculation.
- ELISA showed lower sensitivity in experimental infections due to antibody response time.
Conclusions:
- Diagnostic method efficacy for Mycoplasma pulmonis varies between natural and experimental infections.
- Isolation is the most reliable single method for experimental infections, especially when sampling multiple respiratory sites.
- ELISA is highly effective for naturally infected rats.
- Combining diagnostic methods significantly enhances the detection rate of M. pulmonis in both infection models.