How can mycoplasmosis be diagnosed in rats? - briefly
Detection relies on laboratory testing: serologic assays (ELISA or IFA) and PCR of respiratory samples are the primary methods, while culture and histopathology provide confirmatory evidence. Samples such as oropharyngeal swabs, lung tissue, or blood should be collected aseptically for analysis.
How can mycoplasmosis be diagnosed in rats? - in detail
Mycoplasma infection in laboratory rats is identified through a combination of clinical assessment, laboratory testing, and post‑mortem examination.
Initial evaluation focuses on observable symptoms such as respiratory distress, nasal discharge, weight loss, and reduced reproductive performance. Because clinical signs are often nonspecific, laboratory confirmation is essential.
Sample collection
- Nasal or oropharyngeal swabs for live animal testing.
- Lung tissue, trachea, and spleen obtained during necropsy for culture or molecular analysis.
- Blood serum for antibody detection.
All specimens should be processed promptly under sterile conditions to prevent contamination.
Serological methods
Enzyme‑linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA) detect antibodies against Mycoplasma pulmonis and related species. Positive titers indicate exposure, but may not differentiate active infection from prior exposure; serial testing improves reliability.
Molecular detection
Polymerase chain reaction (PCR) targeting the 16S rRNA gene provides rapid, specific identification of mycoplasmal DNA in swabs or tissue homogenates. Real‑time quantitative PCR (qPCR) quantifies bacterial load, aiding in disease severity assessment. Proper primer selection and inclusion of positive controls prevent false‑negative results.
Culture
Mycoplasmas require specialized media (e.g., SP4 broth) and incubation at 37 °C with 5 % CO₂. Growth is slow, often taking 2–4 weeks, and colonies appear as “fried‑egg” formations under microscopy. Culture remains the definitive method but is labor‑intensive and less practical for routine screening.
Histopathology and immunohistochemistry
Fixed lung sections stained with hematoxylin‑eosin reveal peribronchial lymphoid hyperplasia, alveolar infiltrates, and epithelial necrosis typical of mycoplasmal pneumonia. Immunohistochemical labeling with species‑specific antibodies confirms the presence of organisms within lesions.
Interpretation
A positive PCR or culture result from respiratory samples, combined with compatible histopathology and serology, confirms active infection. Isolated seropositivity without molecular or culture evidence suggests prior exposure or low‑level colonization. Regular health monitoring programs incorporate a tiered approach—serology for surveillance, PCR for rapid confirmation, and culture for strain isolation when necessary.
Effective diagnosis relies on timely sample acquisition, appropriate test selection, and integration of multiple data sources to distinguish infection from mere exposure.