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Differences in the pathogenesis of bacteria isolated from contact-lens-induced infiltrative conditions
1Cooperative Research Centre for Eye Research and Technology, School of Optometry, University of New South Wales, Sydney, Australia. m.willcox@cclru.randwick.unsw.edu.au
Purpose:
The purpose of this study was to examine the ability of gram-negative bacteria isolated from the non-infectious condition contact-lens-induced acute red eye (CLARE) and infectious microbial keratitis (MK) to infect the eyes of mice.
Methods:
One cornea of BALB/c mice was scratched with a needle and 5 x 10(6) bacteria applied. Bacterial types used were Pseudomonas aeruginosa, Haemophilus influenzae, Serratia marcescens, Stenotrophomonas moltophilia and Aeromonas hydrophilia. The mice were killed after 1, 4 and 24 h and examined by slit lamp, histology and microbiology.
Results:
CLARE strains were unable to infect the mouse corneas. The eyes inoculated with the CLARE strains had low levels of polymorphonuclear leucocytes (PMN) in the stroma. All eyes that had MK contained bacteria and large numbers of PMN after 24 h.
Conclusions:
The development of CLARE or MK is dependent on the type of bacteria with specific bacterial types being responsible for CLARE or MK.
Insights
Gram-negative bacteria from contact lens-induced acute red eye (CLARE) and microbial keratitis (MK) show different infection abilities. CLARE strains did not infect mouse corneas, unlike MK strains, indicating bacterial type dictates disease development.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Contact lens-induced acute red eye (CLARE) and microbial keratitis (MK) are common ocular conditions.
- Gram-negative bacteria are implicated in both CLARE and MK.
Purpose of the Study:
- To compare the infectious potential of gram-negative bacteria isolated from CLARE and MK in a mouse eye model.
- To determine if bacterial species dictate the development of CLARE or MK.
Main Methods:
- BALB/c mice corneas were scratched and inoculated with specific gram-negative bacteria (Pseudomonas aeruginosa, Haemophilus influenzae, Serratia marcescens, Stenotrophomonas maltophilia, Aeromonas hydrophila).
- Inoculated eyes were examined at 1, 4, and 24 hours post-inoculation using slit lamp, histology, and microbiology.
Main Results:
- Bacteria isolated from CLARE failed to establish infection in mouse corneas.
- CLARE-inoculated eyes showed minimal polymorphonuclear leukocyte (PMN) infiltration.
- Eyes inoculated with microbial keratitis strains demonstrated bacterial presence and significant PMN infiltration within 24 hours.
Conclusions:
- The development of CLARE versus MK is contingent upon the specific bacterial species involved.
- Distinct bacterial types are responsible for causing either CLARE or MK, highlighting pathogen-specific virulence.