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Carrier state of Pasteurella pneumotropica in mice and rats
Abstract:
Localization of Pasteurella pneumotropica was investigated in the respiratory tract, conjunctiva and vagina of 5-week-old, 10-week-old and retired asymptomatic mice and rats. The highest isolation rate of the organisms was obtained in the pharyngolarynx, showing 85 to 97.5% in carrier mice and 100% in carrier rats. Numbers of the organisms in this site were 10(3-5) and 10(7-8) organisms/g tissue in 4-week-old mice and rats, respectively. Isolation rates in the nasal cavity and trachea of the both animals were not so high as those in the pharyngolarynx, but usually higher than those in the external nares. The organisms were rarely isolated from the lung. Isolation of the organisms from the conjunctiva was common in rats, especially in young ones, but rare in mice. About 30% of carrier mice and 50 to 100% of carrier rats harbored the organisms in their vaginas.
Insights
Pasteurella pneumotropica primarily colonizes the pharyngolarynx in mice and rats. This bacterium was also found in the vagina and conjunctiva, particularly in rats, but rarely in the lungs.
Area of Science:
- Microbiology
- Veterinary Medicine
- Infectious Diseases
Background:
- Pasteurella pneumotropica is a common bacterium found in rodents.
- Understanding its colonization sites is crucial for disease control in research animal populations.
Purpose of the Study:
- To determine the primary colonization sites of Pasteurella pneumotropica in mice and rats.
- To investigate the prevalence of P. pneumotropica in the respiratory tract, conjunctiva, and vagina of asymptomatic rodents.
Main Methods:
- Investigated the localization of Pasteurella pneumotropica in 5-week-old, 10-week-old, and retired asymptomatic mice and rats.
- Sampled the respiratory tract (pharyngolarynx, nasal cavity, trachea, external nares, lung), conjunctiva, and vagina.
- Quantified bacterial load in specific sites.
Main Results:
- The pharyngolarynx showed the highest isolation rates (85-100%) and bacterial loads (10^3-10^8 organisms/g tissue).
- Nasal cavity and trachea had moderate isolation rates, while lungs rarely harbored the bacteria.
- Conjunctival isolation was common in rats (especially young) but rare in mice; vaginal colonization occurred in 30% of mice and 50-100% of rats.
Conclusions:
- The pharyngolarynx is the principal reservoir for Pasteurella pneumotropica in mice and rats.
- Vaginal and conjunctival carriage can occur, with higher prevalence in rats.
- These findings aid in understanding Pasteurella pneumotropica epidemiology and inform diagnostic and control strategies in rodent colonies.