The effectiveness of lysostaphin therapy for experimental coagulase-negative Staphylococcus endophthalmitis.

Abstract

PURPOSE:

To quantitatively determine the effectiveness of lysostaphin therapy for experimental endophthalmitis mediated by coagulase-negative Staphylococcus species, the leading cause of postsurgical endophthalmitis.

METHODS:

Minimal inhibitory concentrations (MIC) of lysostaphin were determined for 54 isolates representing the following species: S. epidermidis, S. warneri, S. haemolyticus, S. cohnii, S. simulans, and S. capitis. The effectiveness of lysostaphin therapy was tested in an experimental model of endophthalmitis by intravitreally injecting log phase bacteria (100 colony-forming units; cfu) into rabbit eyes (n = 3 eyes per group). At 8 hr postinfection (PI), lysostaphin (250 microg) was injected intravitreally, and the number of cfu/ml of vitreous was determined at 24 hr PI.

RESULTS:

Average MIC for S. epidermidis was 0.7 microg/ml for 90% of the 33 strains tested. Six methicillin-resistant strains of S. epidermidis (MRSE) had an average MIC of 0.74 micro g/ml. All other species had MIC values of =1.1 microg/ml, except for one strain of S. capitis (MIC = 15.6 microg/ml) and one S. haemolyticus (MIC = 1.41 microg/ml). At 24 hr PI, all untreated eyes had between 5.7 and 8.08 log cfu/ml vitreous humor. Treatment with lysostaphin significantly reduced the cfu/ml as compared with untreated eyes for 13 strains tested in vivo (p = 0.020), but not for two S. haemolyticus strains (p = 0.13), two MRSE strains (p = 0.544), or one S. cohnii strain (p = 0.1366). Treatment with lysostaphin reduced the cfu/ml of methicillin-sensitive S. epidermidis strains by 6 logs; for S. warneri, there was a 2 log reduction; and for the other species a 4 log reduction in cfu/ml relative to untreated eyes.

CONCLUSIONS:

Lysostaphin was mostly effective in treating coagulase-negative staphylococcal experimental endophthalmitis.

• Authors: Clare C McCormick, Joseph J Dajcs, Julian M Reed, Mary E Marquart, Richard J O'Callaghan
• Journal: Current eye research (Curr Eye Res) Vol. 31 Issue 3 Pg. 225-30 (Mar 2006) ISSN: 0271-3683 [Print] England
• PMID: 16531279 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Infective Agents, Local
• Lysostaphin

Topics

• Animals
• Anti-Infective Agents, Local (administration & dosage, therapeutic use)
• Disease Models, Animal
• Endophthalmitis (drug therapy, microbiology)
• Eye Infections, Bacterial (drug therapy, microbiology)
• Injections
• Lysostaphin (administration & dosage, therapeutic use)
• Rabbits
• Staphylococcal Infections (drug therapy, microbiology)
• Staphylococcus (isolation & purification)
• Treatment Outcome
• Vitreous Body (microbiology)