Pseudomonas aeruginosa LasA Protease in Treatment of Experimental Staphylococcal Keratitis

ABSTRACT LasA protease is a staphylolytic endopeptidase secreted by Pseudomonas aeruginosa. We have examined the effectiveness of LasA protease in the treatment of staphylococcal keratitis caused by methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolates in a rabbit model. Keratitis was induced by intrastromal injection of the bacteria. The eyes were treated topically, and the efficacy of LasA protease was compared to those of lysostaphin (a staphylolytic protease secreted by Staphylococcus simulans) and vancomycin. When treatment was initiated early (4 h) after infection, practically all of the MSSA- and MRSA-infected corneas were sterilized by LasA protease, and its efficacy in eradicating the bacteria was comparable to those of lysostaphin and vancomycin. By contrast, most of the control corneas were heavily infected, with median values of 4.5 × 106 (MSSA) and 5 × 105 (MRSA) CFU/cornea (P < 0.001). When treatment was initiated late (10 h) after infection, LasA protease reduced the numbers of CFU in both MSSA- and MRSA-infected corneas by 3 to 4 orders of magnitude compared to the numbers of CFU for the controls (median values, 1,380 and 30 CFU/cornea, respectively, for the treated animals compared to 1.2 × 106 and 5 × 105 CFU/cornea for the respective controls [P = 0.001]), and it was more effective than vancomycin in eradicating MRSA cells (P = 0.02). In both the early- and the late-treatment protocols, the clinical scores for eyes treated with LasA protease were significantly lower than those for the eyes of the corresponding controls and comparable to those for the lysostaphin- and vancomycin-treated eyes. We conclude that LasA protease is effective in the treatment of experimental S. aureus keratitis in rabbits and may have potential for the treatment of disease in humans.

[1]  R. O'Callaghan,et al.  Immunity to lysostaphin and its therapeutic value for ocular MRSA infections in the rabbit. , 2002, Investigative ophthalmology & visual science.

[2]  Arjun Srinivasan,et al.  Vancomycin Resistance in Staphylococci , 2002, Clinical Microbiology Reviews.

[3]  J. A. Hobden.  Pseudomonas aeruginosa proteases and corneal virulence. , 2002, DNA and cell biology.

[4]  R. O'Callaghan,et al.  Corneal Virulence of LasA Protease-deficient Pseudomonas aeruginosa PAO1 , 2001, Cornea.

[5]  L. Zografos,et al.  Bacterial keratitis: a prospective clinical and microbiological study , 2001, The British journal of ophthalmology.

[6]  J. Seal,et al.  Evolving antimicrobial chemotherapy for Staphylococcus aureus infections: Our backs to the wall. , 2001, Critical care medicine.

[7]  J. Saulnier,et al.  Hydrolysis of glycine-containing elastin pentapeptides by LasA, a metalloelastase from Pseudomonas aeruginosa. , 2001, European journal of biochemistry.

[8]  J. A. Hobden,et al.  Pseudomonas aeruginosa LasA protease and corneal infections , 2001, Current eye research.

[9]  E. Hume,et al.  Lysostaphin is effective in treating methicillin-resistant Staphylococcus aureus endophthalmitis in the rabbit , 2001, Current eye research.

[10]  G. Alexandrakis,et al.  Shifting trends in bacterial keratitis in south Florida and emerging resistance to fluoroquinolones. , 2000, Ophthalmology.

[11]  E. Hume,et al.  Lysostaphin treatment of methicillin-resistant Staphylococcus aureus keratitis in the rabbit. , 2000, Investigative ophthalmology & visual science.

[12]  J. Baum,et al.  Emerging fluoroquinolone resistance in bacterial keratitis: A 5-year review , 1999 .

[13]  G. Archer,et al.  Lysostaphin Treatment of Experimental Aortic Valve Endocarditis Caused by a Staphylococcus aureus Isolate with Reduced Susceptibility to Vancomycin , 1999, Antimicrobial Agents and Chemotherapy.

[14]  D. Ohman,et al.  Elastase and the LasA Protease of Pseudomonas aeruginosa Are Secreted with Their Propeptides* , 1998, The Journal of Biological Chemistry.

[15]  G. Archer,et al.  Lysostaphin Treatment of Experimental Methicillin-Resistant Staphylococcus aureus Aortic Valve Endocarditis , 1998, Antimicrobial Agents and Chemotherapy.

[16]  J. Goldberg,et al.  Contribution of proteases and LasR to the virulence of Pseudomonas aeruginosa during corneal infections , 1997, Infection and immunity.

[17]  J. Rosenbloom,et al.  Inhibitors and Specificity of Pseudomonas aeruginosa LasA* , 1997, The Journal of Biological Chemistry.

[18]  D. Ohman,et al.  A substitution at His-120 in the LasA protease of Pseudomonas aeruginosa blocks enzymatic activity without affecting propeptide processing or extracellular secretion , 1996, Journal of bacteriology.

[19]  O. Schneewind,et al.  Target cell specificity of a bacteriocin molecule: a C‐terminal signal directs lysostaphin to the cell wall of Staphylococcus aureus. , 1996, The EMBO journal.

[20]  James M. Hill,et al.  Pharmacokinetic Considerations in the Treatment of Bacterial Keratitis , 1994, Clinical pharmacokinetics.

[21]  D. Ohman,et al.  Secreted LasA of Pseudomonas aeruginosa is a staphylolytic protease. , 1993, The Journal of biological chemistry.

[22]  J. A. Hobden,et al.  Methicillin-resistant Staphylococcus aureus keratitis in the rabbit: therapy with ciprofloxacin, vancomycin and cefazolin. , 1992, Current eye research.

[23]  M. Snyder,et al.  Ciprofloxacin-resistant bacterial keratitis. , 1992, American journal of ophthalmology.

[24]  J. Rossi,et al.  Effect of Enrichment Procedure upon Auxotroph Recovery in Escherichia coli K-12 , 1975, Antimicrobial Agents and Chemotherapy.

[25]  W. Schaffner,et al.  Efficacy and safety of topical lysostaphin treatment of persistent nasal carriage of Staphylococcus aureus. , 1971, Applied microbiology.

[26]  J. S. Goodman,et al.  Lysostaphin: an enzymatic approach to staphylococcal disease. 3. Combined lysostaphin-methicillin therapy of established staphylococcal abscesses in mice. , 1968, The Yale journal of biology and medicine.

[27]  C. Schindler,et al.  LYSOSTAPHIN: A NEW BACTERIOLYTIC AGENT FOR THE STAPHYLOCOCCUS. , 1964, Proceedings of the National Academy of Sciences of the United States of America.

[28]  R. Howe,et al.  The prevalence and mechanisms of vancomycin resistance in Staphylococcus aureus. , 2002, Annual review of microbiology.

[29]  J. Krachmer,et al.  Cornea and external disease : clinical diagnosis and management , 1997 .

[30]  E. Kessler.  [48] β-lytic endopeptidases , 1995 .

[31]  T. Kern.  Ulcerative keratitis. , 1990, The Veterinary clinics of North America. Small animal practice.

[32]  A. Carnicero,et al.  Purification and peptidase activity of a bacteriolytic extracellular enzyme from Pseudomonas aeruginosa. , 1989, Research in microbiology.

[33]  A. Carnicero,et al.  Effects of staphylolytic enzymes from Pseudomonas aeruginosa on the growth and ultrastructure of Staphylococcus aureus. , 1987, Microbios.

[34]  F. Perestelo,et al.  Growth inhibition of Staphylococcus aureus by a staphylolytic enzyme from Pseudomonas aeruginosa , 1985 .

[35]  P. Asbell,et al.  Ulcerative keratitis. Survey of 30 years' laboratory experience. , 1982, Archives of ophthalmology.

[36]  W. Zygmunt,et al.  Lysostaphin: model for a specific enzymatic approach to infectious disease. , 1972, Progress in drug research. Fortschritte der Arzneimittelforschung. Progres des recherches pharmaceutiques.

[37]  E. F. Harrison,et al.  Therapeutic activity of lysostaphin in experimental staphylococcal infections. , 1967 .