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Updated: Nov 21, 2025
Conjunctival Commensal Isolation and Identification in Mice
Published on: May 1, 2021
Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice
Vunjia Tiong1, Shih-Keng Loong1, Haryanti Azura Mohamad Wali2
1Tropical Infectious Diseases Research & Education Centre, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Abstract:
Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.
Insights
Streptococcus cuniculi caused corneal lesions and ocular discharge in laboratory mice. This opportunistic bacterium colonizes mice and should be considered in diagnosing eye conditions in laboratory rodents.
Area of Science:
- Veterinary microbiology
- Laboratory animal science
- Ophthalmology
Background:
- Corneal lesions and ocular discharge were observed in BALB/c laboratory mice.
- Affected mice maintained normal health indicators, suggesting a localized infection.
Purpose of the Study:
- To identify the causative agent of corneal lesions in laboratory mice.
- To investigate the potential role of Streptococcus cuniculi in rodent eye infections.
Main Methods:
- Bacterial isolation and culture from ocular swabs of affected mice.
- Partial 16S rRNA gene sequencing for bacterial identification.
- Antibiotic susceptibility testing of the isolated bacteria.
Main Results:
- Isolates showed 99.1% 16S rRNA gene sequence similarity to Streptococcus cuniculi.
- This is the first reported instance of S. cuniculi infection in laboratory rodents.
- The identified S. cuniculi isolate was susceptible to all tested antibiotics.
Conclusions:
- Streptococcus cuniculi can colonize laboratory mice, presenting as an opportunistic pathogen.
- S. cuniculi should be considered in the differential diagnosis of eye lesions and ocular discharge in laboratory mice.
- The source of S. cuniculi in this laboratory setting remains undetermined.
