Correlation of Phenotype and Its Corneal Virulence.

Purpose: is an ocular pathogen and a leading cause of keratitis. It produces hemolysins and at least 3 proteases. The purpose of the present study is to compare the secretion of hemolysins and proteases between 28 ocular isolates and one non-ocular strain and to determine their relationship to ocular virulence in selected strains using a rabbit model of infection.

Keratitis: Protease IV and PASP as Corneal Virulence Mediators.

is a leading cause of bacterial keratitis, especially in users of contact lenses. These infections are characterized by extensive degradation of the corneal tissue mediated by protease activities, including both protease IV (PIV) and the small protease (PASP). The virulence role of PIV was determined by the reduced virulence of a PIV-deficient mutant relative to its parent strain and the mutant after genetic complementation (rescue).

Superantigen-Like Protein SSL1: A Toxic Protease.

is a major cause of corneal infections that can cause reduced vision, even blindness. Secreted toxins cause tissue damage and inflammation resulting in scars that lead to vision loss. Identifying tissue damaging proteins is a prerequisite to limiting these harmful reactions.

Mechanism of Pseudomonas aeruginosa Small Protease (PASP), a Corneal Virulence Factor.

Purpose: Pseudomonas aeruginosa is the leading cause of contact lens-associated bacterial keratitis. Secreted bacterial proteases have a key role in keratitis, including the P. aeruginosa small protease (PASP), a proven corneal virulence factor.

Protease IV Exacerbates Pneumococcal Pneumonia and Systemic Disease.

Pneumonia is a pulmonary disease affecting people of all ages and is consistently a leading cause of childhood mortality and adult hospitalizations. and are major lung pathogens commonly associated with community-acquired and nosocomial pneumonia. Additionally, mixed lung infections involving these bacterial pathogens are increasing in prevalence and are frequently more severe than single infections.

The Pathogenesis of Staphylococcus aureus Eye Infections.

is a major pathogen of the eye able to infect the tear duct, eyelid, conjunctiva, cornea, anterior and posterior chambers, and the vitreous chamber. Of these infections, those involving the cornea (keratitis) or the inner chambers of the eye (endophthalmitis) are the most threatening because of their potential to cause a loss in visual acuity or even blindness. Each of these ocular sites is protected by the constitutive expression of a variety of antimicrobial factors and these defenses are augmented by a protective host response to the organism.

Reactions with Antisera and Pathological Effects of Staphylococcus aureus Gamma-Toxin in the Cornea.

Purpose: This study analyzed the toxicity of purified gamma-toxin from Staphylococcus aureus and the protectiveness of antisera to gamma-toxin in the rabbit cornea.

Materials And Methods: Gamma-toxin was purified from cultures of alpha-toxin deficient S. aureus strain Newman Δhla.

Pseudomonas aeruginosa proteolytically alters the interleukin 22-dependent lung mucosal defense.

The IL-22 signaling pathway is critical for regulating mucosal defense and limiting bacterial dissemination. IL-22 is unusual among interleukins because it does not directly regulate the function of conventional immune cells, but instead targets cells at outer body barriers, such as respiratory epithelial cells. Consequently, IL-22 signaling participates in the maintenance of the lung mucosal barrier by controlling cell proliferation and tissue repair, and enhancing the production of specific chemokines and anti-microbial peptides.

Strategies for decreasing contamination of homemade nasal saline irrigation solutions.

Background: Saline nasal irrigations (SNI) are an important adjunct in the treatment of rhinosinusitis, and many patients prepare and store these solutions in their homes without an awareness of the potential for contamination. The objectives of this study were to determine if such contamination occurs and the effect of preparation methods on contamination.

Methods: Stock solutions of various tonicities and pHs were prepared using boiled, bottled, and distilled water (n = 57).

Staphylococcus Alpha-Toxin Action on the Rabbit Iris: Toxic Effects and Their Inhibition.

Purpose: Staphylococcus aureus infection of the anterior chamber can occur after cataract surgery, causing inflammation and extensive damage to the iris. Alpha-toxin, the most potent S. aureus corneal toxin, was tested as a possible mediator of damage to the iris, and alpha-toxin anti-serum and a chemical toxin inhibitor were tested as potential pathology-reducing agents.

Effectiveness of Alpha-toxin Fab Monoclonal Antibody Therapy in Limiting the Pathology of Staphylococcus aureus Keratitis.

Purpose: To investigate the effectiveness of a high-affinity human monoclonal antibody Fab fragment to Staphylococcus aureus alpha-toxin (LTM14 Fab) as therapy for S. aureus keratitis.

Methods: A single topical drop of the LTM14 Fab antibody to alpha-toxin alone, or in 0.

Pseudomonas aeruginosa small protease (PASP), a keratitis virulence factor.

Purpose: The virulence contribution of Pseudomonas aeruginosa small protease (PASP) during experimental keratitis was studied by comparing a PASP-deficient mutant with its parent and rescue strains.

Methods: The pasP gene of P. aeruginosa was replaced with the tetracycline resistance gene via allelic exchange.

Infectious keratitis: secreted bacterial proteins that mediate corneal damage.

Ocular bacterial infections are universally treated with antibiotics, which can eliminate the organism but cannot reverse the damage caused by bacterial products already present. The three very common causes of bacterial keratitis-Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae-all produce proteins that directly or indirectly cause damage to the cornea that can result in reduced vision despite antibiotic treatment. Most, but not all, of these proteins are secreted toxins and enzymes that mediate host cell death, degradation of stromal collagen, cleavage of host cell surface molecules, or induction of a damaging inflammatory response.

Staphylococcus aureus infection of the rabbit cornea following topical administration.

Purpose: To determine the ability of diverse S. aureus strains to infect the rabbit cornea following topical inoculation, with special emphasis on a strain of unusual virulence.

Materials And Methods: S.

Identification and potency of cyclodextrin-lipid inhibitors of Staphylococcus aureus α-toxin.

Purpose: Staphylococcus aureus, a leading cause of bacterial keratitis, secretes α-toxin, a cytotoxin active on the corneal epithelium. This study describes the production and testing of chemical inhibitors of α-toxin action.

Methods: Purified α-toxin was titered by its ability to lyse rabbit erythrocytes in buffered saline (PBS).

Diverse virulence of Staphylococcus aureus strains for the conjunctiva.

Purpose: To determine the virulence of Staphylococcus aureus strains in the rabbit conjunctiva.

Methods: Three strains of methicillin-sensitive S. aureus (8325-4, Newman, and UMCR1) and two strains of methicillin-resistant S.

Penetration and effectiveness of prophylactic fluoroquinolones in experimental methicillin-sensitive or methicillin-resistant Staphylococcus aureus anterior chamber infections.

Purpose: To determine the effectiveness of moxifloxacin and besifloxacin prophylactic therapy for experimental Staphylococcus aureus infections originating in the rabbit anterior chamber.

Setting: Microbiology Department, University of Mississippi Medical Center, Jackson, Mississippi, USA.

Design: Experimental study.

The effectiveness of an improved combination therapy for experimental Staphylococcus aureus keratitis.

Introduction: antibiotic and steroid combination therapies, such as tobramycin with dexamethasone, are often used in ophthalmology to treat or prevent infection and inflammation. The purpose of this study was to use a model of Staphylococcus aureus keratitis to quantify and compare the effectiveness of a standard tobramycin and dexamethasone combined therapy, with each drug individually, and with a new formulation of the two drugs in a xanthan gum vehicle.

Methods: rabbit corneas were intrastromally injected with a methicillin-sensitive S.

Sustained anti-staphylococcal effect of lysostaphin in the rabbit aqueous humor.

Purpose: Staphylococcus aureus is an important cause of ocular infections including endophthalmitis. The purpose of this study was to determine the ability of a relatively large molecule, such as lysostaphin, to remain in the rabbit aqueous humor for extended periods while retaining its bactericidal activity.

Methods: Lysostaphin, gatifloxacin, or Tris-buffered saline (TBS) was injected into the rabbit anterior chamber.

A highly virulent Staphylococcus aureus: rabbit anterior chamber infection, characterization, and genetic analysis.

Purpose: To describe and characterize a Staphylococcus aureus strain with unique virulence that overcomes host defenses of the rabbit anterior chamber and mimics clinical cases of postcataract surgery endophthalmitis.

Methods: Nine isolates of S. aureus were tested to determine their viability in the rabbit anterior chamber.

Development of a Streptococcus pneumoniae keratitis model in mice.

Background: Streptococcus pneumoniae is a common cause of bacterial keratitis, and models to examine the ocular pathogenesis of this bacterium would aid in efforts to treat pneumococcal keratitis. The aim of this study was to establish a murine model of pneumococcal keratitis.

Methods: The corneas of A/J, BALB/c or C57BL/6 mice were scratched and topically infected with a clinical strain of S.

Properties of PASP: a Pseudomonas protease capable of mediating corneal erosions.

Purpose: To analyze PASP in terms of its gene distribution and expression, its corneal pathologic effects, its enzymatic properties, and the protectiveness of the immune response to this protease.

Methods: Twenty-five strains of P. aeruginosa were analyzed for the PASP gene and secreted protein by PCR and Western blot analysis, respectively.

Chemical inhibition of alpha-toxin, a key corneal virulence factor of Staphylococcus aureus.

Purpose: alpha-Toxin mediates extreme corneal damage during Staphylococcus aureus keratitis. Chemical inhibition of this toxin was sought to provide relief from toxin-mediated pathology.

Methods: Inhibition of alpha-toxin by phosphate-buffered saline (PBS), 0.