What is Mycoplasma infection in rats? - briefly
Mycoplasma infection in rats is a bacterial disease caused chiefly by Mycoplasma pulmonis, which colonizes the respiratory tract and may disseminate to other organs. Clinical manifestations include nasal discharge, sneezing, and stunted growth, with transmission occurring through direct contact or aerosol exposure.
What is Mycoplasma infection in rats? - in detail
Mycoplasma organisms are cell‑wall‑deficient bacteria that colonize the respiratory and urogenital tracts of laboratory rodents. In rats, infection typically involves species such as Mycoplasma pulmonis, Mycoplasma arthritidis and Mycoplasma pneumoniae‑related strains. Transmission occurs through direct contact, aerosol droplets, contaminated bedding, and fomites; vertical spread from dam to offspring is also documented.
Clinical manifestations range from subclinical carriage to overt disease. Respiratory signs include nasal discharge, sneezing, dyspnea and interstitial pneumonia visible on histopathology. Musculoskeletal involvement may present as polyarthritis, joint swelling, and lameness, especially with M. arthritidis. Systemic effects can involve otitis media, conjunctivitis, and reproductive tract pathology, leading to reduced fertility and increased embryonic loss.
Diagnosis relies on a combination of methods:
- Culture on specialized mycoplasma media under microaerophilic conditions; colonies appear as “fried‑egg” morphology.
- Polymerase chain reaction (PCR) targeting species‑specific 16S rRNA or housekeeping genes; provides rapid and sensitive detection.
- Serology (ELISA, immunofluorescence) to identify antibodies; useful for surveillance but may not differentiate active infection.
- Histopathology revealing characteristic peribronchiolar infiltrates and fibroplasia.
Control strategies emphasize prevention and eradication:
- Barrier housing with filtered air and autoclaved bedding to limit exposure.
- Quarantine of new arrivals with PCR screening before integration.
- Regular health monitoring using sentinel animals and periodic testing of colony samples.
- Antibiotic therapy (e.g., tetracyclines, macrolides) applied cautiously because mycoplasmas lack a cell wall and may develop resistance; treatment often reduces bacterial load but does not guarantee complete clearance.
- Depopulation and rederivation (embryo transfer, cesarean section) for heavily infected colonies.
Pathogenesis involves adhesion to epithelial cells via specialized surface proteins, causing cellular damage through nutrient depletion and immune evasion. The host response includes recruitment of neutrophils, macrophages, and production of cytokines such as IL‑1β and TNF‑α, which contribute to tissue inflammation and fibrosis.
Research implications are significant: Mycoplasma infection can confound experimental outcomes by altering immune parameters, respiratory physiology, and behavior. Consequently, accreditation bodies require documented freedom from these agents for facilities engaged in toxicology, pharmacology, and immunology studies.
In summary, mycoplasmal disease in rats is a multifaceted condition characterized by respiratory and musculoskeletal pathology, transmissible through multiple routes, diagnosable by culture, PCR, and serology, and manageable through stringent biosecurity, routine surveillance, and, when necessary, targeted antimicrobial regimens.