Bacterial adherence to soft contact lenses.
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Bacterial Adhesion↗
Biomedical subjects
M Barza
Publications and source records attributed to M Barza.
Binding of Pseudomonas aeruginosa to neutral glycosphingolipids of rabbit corneal epithelium.
35S-labeled Pseudomonas aeruginosa isolates were shown to bind to neutral glycosphingolipids (NGSLs) of rabbit corneal epithelia in culture by a thin-layer chromatogram overlay procedure. The lipids of the corneal epithelial cells grown in culture were extracted and partitioned into a chloroform-rich lower phase containing NGSLs and an aqueous upper phase containing gangliosides. By using a dot-blot assay, at least six times more radiolabeled P. aeruginosa isolates were shown to bind to the lipids in the lower phase compared with those in the upper phase. Thin-layer chromatography of the lower-phase lipids followed by staining with an orcinol spray revealed at least 10 NGSL components and several fast-migrating, nonglycosylated neutral lipid components (including cholesterol). 35S-labeled P. aeruginosa was shown to bind to NGSL components 1, 2, 5, 6, and 9. P. aeruginosa-reactive NGSL components 6 and 9 migrated with chromatographic mobilities similar to those of the standards ceramide trihexoside (CT) and ceramide monohexoside, respectively. Components 1 and 2 migrated slightly ahead of asialo GM1, and component 5 migrated faster than globoside but slower than CT. Among the various standards tested, P. aeruginosa bound to asialo GM1 and, to a lesser extent, to ceramide dihexoside and CT but not to GM1, GD1A, GM3, or ceramide monohexoside. It remains to be determined whether any of the five P. aeruginosa-reactive NGSL components of corneal epithelium identified in this study plays a role in the development of corneal infection. However, we have previously shown that component 9, one of the five P. aeruginosa-reactive NGSL components identified in this study, is present in significantly greater amounts in migrating epithelia than it is in nonmigrating epithelia (N. Panjwani, G. Michalopoulos, J. Song, G. Yogeeswaran, and J. Baum, Invest. Ophthalmol. Vis. Sci., in press). This may prove to be of biological significance because it is generally believed that traumatized (migrating) epithelia are more susceptible to infection than normal (nonmigrating) epithelia are.
Animals↗
Differential binding of P. aeruginosa and S. aureus to corneal epithelium in culture.
Adherence of bacteria to corneal epithelium is a prerequisite for corneal infection. We used two methods to study the binding of Pseudomonas aeruginosa and Staphylococcus aureus to rabbit corneal epithelial cells in culture. In the first method, rabbit corneal epithelial cells grown on glass slides were incubated with P. aeruginosa or S. aureus (10(7) CFU/ml) at room temperature for 90 min, and the bacterial binding to the epithelial cells was examined by light microscopy. Both P. aeruginosa and S. aureus bound to epithelial cells. P. aeruginosa was bound to the cell periphery whereas S. aureus was bound randomly to the cell surface. In the second method, suspension cultures of corneal epithelial cells were used. In contrast to the findings in cultures on slides, binding pattern with cells in suspension was similar for both species and resembled that for S. aureus in cultures on slides. A much greater number of P. aeruginosa (186 +/- 11 bacteria/epithelial cell) than S. aureus (30 +/- 1.5 bacteria/epithelial cell) bound to epithelial cells grown on glass slides. In contrast, a similar number of P. aeruginosa (25 +/- 5.1) and S. aureus (20 +/- 4.7) bound to epithelial cells grown in suspension cultures. Using either method, Escherichia coli and Streptococcus pyogenes did not bind significantly (less than 5/cell) to corneal epithelial cells. The above methods should prove useful for characterization of bacterial binding to corneal epithelial cells in culture.
Animals↗
The expanding ophthalmologic spectrum of Lyme disease.
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Adrenal Cortex Hormones↗
Effect of lid closure on contact lens-associated Pseudomonas keratitis.
New or used extended-wear soft contact lenses, preincubated in suspensions of Pseudomonas aeruginosa, were placed on the corneas of rabbits. The lids were then sutured shut for either 1 or 2 weeks. Bacterial keratitis occurred in 9 of 9 eyes fitted with the used contaminated lenses but in none of 12 eyes fitted with new contaminated or new noncontaminated lenses. Similar experiments were carried out with other lenses specifically designed to fit the cornea of rabbits. Some of these lenses were preworn by rabbits for 1 week (used), whereas others were new. A significantly greater incidence of bacterial keratitis was found in eyes that had undergone lid closure after the placement of used contaminated lenses (4 of 5) than in closed eyes with new contaminated lenses (1 of 8) and in open eyes with used contaminated lenses (0 of 13). These findings suggest that extended eyelid closure is a risk factor in the experimental model and may be a factor in clinical Pseudomonas keratitis associated with the wearing of extended-wear soft contact lenses.
Animals↗
Guidelines for reports of clinical studies.
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Journal Article↗
Antibacterial agents in the treatment of ocular infections.
There are a number of barriers to the ocular transport of poorly lipid-soluble antibiotics such as beta-lactams and aminoglycosides. Knowledge of these barriers can help the physician in the choice of agent and the route of administration for specific ocular infections. Because of the corneal epithelial barrier, topically applied drugs should be administered frequently; "fortified" drops afford higher corneal concentrations than commercially available drops. Periocular injections may occasionally be of benefit in the treatment of refractory corneal ulcers. The mainstay of treatment of bacterial endophthalmitis should be intravitreal injection of antimicrobial agents; ancillary treatments include the periocular and systemic administration of antimicrobial agents, the systemic administration of probenecid, the administration of corticosteroids, and the use of vitrectomy.
Animals↗
Use of antibacterial agents in infections of the central nervous system.
The movement of drugs from the systemic circulation into the central nervous system is restricted by several factors, including the blood-brain and blood-CSF barriers, an active transport system that affects primarily the beta-lactam antibiotics, and the high degree of serum protein binding of certain agents. The functions of the blood-brain and blood-CSF barriers and of the active transport system are reduced but not abolished by inflammation. For most antimicrobial agents, the major determinant of passage aside from serum protein binding is the degree of lipid-solubility of the drug. The beta-lactam and aminoglycoside antibiotics and vancomycin penetrate the central nervous system relatively poorly, whereas chloramphenicol, metronidazole, the fluoroquinolones and trimethoprim-sulfamethoxazole fare better. Knowledge of the relative capacity of various drugs to penetrate the central nervous system after systemic administration may help the physician to choose an optimum regimen for the treatment of bacterial meningitis and brain abscess.
Anti-Bacterial Agents↗
Cefotetan: summary of the symposium from an internist's viewpoint.
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Bacterial Infections↗
Bilateral keratitis as a manifestation of Lyme disease.
An 11-year-old girl developed bilateral keratitis, which we believe was a manifestation of Lyme disease. She had had several attacks of Lyme arthritis and was twice treated with parenteral penicillin. The keratitis developed five years after the initial episode of Lyme arthritis at a time when there were no other manifestations of Lyme disease. It cleared completely in both eyes after topical corticosteroid therapy.
Child↗
Prospective study comparing imipenem-cilastatin with clindamycin and gentamicin for the treatment of serious surgical infections.
Surgical infection remains a leading cause of hospital morbidity and mortality. We compared the efficacy and toxicity of imipenem-cilastatin sodium in 32 patients with that of clindamycin phosphate and gentamicin sulfate in 25 patients. In the imipenem-cilastatin group, 87.5% had a favorable outcome, with a 12.5% failure rate and 13 adverse reactions. In the clindamycin-gentamicin group, 80% had a favorable outcome, with a 20% failure rate and ten adverse reactions. Two significant superinfections with Pseudomonas and Candida were noted in patients treated with impenem-cilastatin. Each group had one case of Clostridium difficile-associated colitis. Cost analysis showed no differences between treatment arms, except in the appendicitis subgroup. For serious surgical infections, single-agent therapy with imipenem-cilastatin appears to be as efficacious as combination therapy with clindamycin and gentamicin.
Adolescent↗
Protection of neutropenic mice from lethal Candida albicans infection by recombinant interleukin 1.
Natural and synthetic immunomodulators that increase nonspecific resistance to infection are also known to induce interleukin 1 (IL 1) production. Previous studies have demonstrated a protective effect of recombinant human IL 1 beta against death from infection caused by Pseudomonas aeruginosa. In the present study we investigated the effect of IL 1 beta or IL 1 alpha on the survival of neutropenic mice with a lethal Candida albicans infection. Mice with cyclophosphamide-induced neutropenia were injected with 3 X 10(5) C. albicans i.v. When 80 ng IL 1 beta was given as a single i.p. injection 24 h before the infection, survival compared to that in control animals was as follows: 100% vs. 97% at 24 h, 83% vs. 70% at 48 h and 70% vs. 23% at 72 h after the infection (p less than 0.01). The effect of IL 1 was also apparent when it was given 1/2 h before or 6 h after the infection. The results obtained with 80 ng IL 1 alpha given at 24 h before infection were similar to that obtained with IL 1 beta. The numbers of Candida cultured from the blood, liver, spleen, and kidney were not significantly different in IL 1 beta-treated and control animals. Passive transfer of serum obtained from mice pretreated with IL 1 to recipient mice did not provide protection against a subsequent lethal candidal infection. In conclusion, the present study demonstrates that IL 1 beta and IL 1 alpha prolong survival in neutropenic mice with a lethal C. albicans infection.
Agranulocytosis↗
Colonization resistance of the human intestinal microflora: testing the hypothesis in normal volunteers.
Colonization resistance is the mechanism whereby the intestinal microflora protects itself against incursion by new and often harmful microorganisms. Some authors have claimed that colonization resistance is related to the integrity of the anaerobic flora, but this point has not been established in humans. In previous studies in our laboratory cefoxitin, piperacillin, cefoperazone or aztreonam were administered intravenously to healthy volunteers in order to study changes in the intestinal flora and acquisition of new strains. Seven of 16 antibiotic-treated subjects were colonized with gram-negative bacilli, but no correlation was observed between this colonization and the suppression of either anaerobes or any other component of the fecal flora. Marked strains of Escherichia coli and Pseudomonas aeruginosa were also administered by mouth in order to test acquisition of new bacteria. The fed bacteria were found in the stools of both antibiotic-treated and control subjects; the antibiotics had no apparent influence on the ability of these strains to colonize the intestinal tract. Our work, along with findings of others, supports the concept that colonization resistance occurs in humans and is diminished by antibiotic administration. However, it does not support the hypothesis that colonization resistance is related to the anaerobic microflora.
Anti-Bacterial Agents↗
A low dose of recombinant interleukin 1 protects granulocytopenic mice from lethal gram-negative infection.
Natural and synthetic immunomodulators that increase nonspecific resistance to infection induce interleukin 1 (IL-1) production. Therefore, we investigated the effect of the administration of IL-1 on the survival of lethally infected granulocytopenic mice. Mice with cyclophosphamide-induced granulocytopenia were injected with approximately 10(7) Pseudomonas aeruginosa in the thigh muscle at time 0; gentamicin was administered 6 hr and 23 hr later. When recombinant human IL-1 beta (one of the two forms of IL-1) was given as a single i.p. injection 24 hr before the infection, survival was increased. Using 80 ng of IL-1 beta per mouse, survival compared to control animals was 98% vs. 71% at 24 hr, 98% vs. 60% at 30 hr, 86% vs. 36% at 36 hr, and 61% vs. 11% at 48 hr (P less than 0.001) after the infection. No effect of IL-1 was observed when it was given 0.5 hr before or 6 hr after the infection. Animals not treated with gentamicin also benefited from the IL-1. Administration of the cyclooxygenase inhibitor ibuprofen did not affect the activity of IL-1. Numbers of bacteria cultured from the blood, thigh muscle, liver, spleen, and kidney were similar in IL-1-treated and control animals. Superoxide production by peritoneal macrophages was also similar in the two groups. These studies demonstrate that IL-1 pretreatment protects granulocytopenic mice against lethal pseudomonas infection and suggest that this protection occurs through a noncellular mechanism.
Agranulocytosis↗
Tolerance of Pseudomonas aeruginosa to killing by ciprofloxacin, gentamicin and imipenem in vitro and in vivo.
In the rat croton oil pouch model, treatment with ciprofloxacin, gentamicin or imipenem caused a sharp reduction in the numbers of Pseudomonas aeruginosa when applied 24 h after infection but treatment had little or no effect when delayed until 48 h after infection. Surviving bacteria from treated animals were fully susceptible on subculture in vitro. Between 24 h and 48 h after infection there was an increase in the concentration of magnesium and a decrease in the concentration of oxygen but no significant change in the pH of the pouch fluid. In-vitro, the MBC of gentamicin was increased four-fold by the addition of magnesium ions and eight-fold under anaerobic conditions whereas these variables had no significant effect upon the MBC of ciprofloxacin and imipenem. However, cells of P. aeruginosa incubated in batch culture for 4, 24 and 48 h became progressively more tolerant to killing by all three drugs. We conclude that the tolerance of P. aeruginosa in vivo was only partly explained by biochemical changes at the site of infection. The stationary growth phase was associated with progressive tolerance to killing by ciprofloxacin, gentamicin and imipenem both in vivo and in vitro.
Animals↗
An organ culture system for study of adherence of Pseudomonas aeruginosa to normal and wounded corneas.
An organ culture system has been developed to study the adherence of Pseudomonas aeruginosa to unwounded corneas and to corneas healing after a 3 mm central epithelial debridement. The Pseudomonas strain was isolated from a human corneal ulcer; suspensions containing 1 X 10(8) colony-forming units/ml (CFU/ml) of bacteria were incubated with the corneas for the last 30 min of the 18 hr culture period. The distribution pattern and number of adherent bacteria on the ocular surface were determined by morphometric analysis of scanning electron micrographs. Few bacteria (25 +/- 15/mm2) adhered to the apical cells of unwounded corneas. There was a definite region-specific distribution of adherent bacteria on healing corneas. There was a definite region-specific distribution of adherent bacteria on healing corneas. Most bacteria were found on the denuded basal lamina in front of the leading edge of the migrating epithelium (360,700 +/- 49,000/mm2). Appreciable but lower numbers adhered to the apical membrane of leading-edge cells (37,700 +/- 6,100/mm2) and to the central portion of the denuded basal lamina (28,800 +/- 10,700/mm2). No bacteria were found adherent to the apical cells of the stratified epithelium behind the leading edge of the epithelium migrating to cover the wound. A similar region-specific distribution of adherent bacteria was found when corneas were inverted in the bacterial suspension and when corneas were incubated in the bacterial suspension for 15 rather than 30 min. Corneas preincubated with the lectin, succinyl-concanavalin A, showed significantly decreased bacterial adherence, indicating a possible role for mannose moieties of wound surface glycoconjugates in bacterial adherence.
Animals↗
Transscleral iontophoresis as an adjunctive treatment for experimental endophthalmitis.
We examined the efficacy of transcleral iontophoresis as an adjunct to intravitreal injection in the treatment of experimental Pseudomonas endophthalmitis in rabbits. Animals received no antibacterial treatment (untreated controls; group 1), a single intravitreal injection of 100 micrograms of gentamicin sulfate (group 2), or the same dose of gentamicin sulfate along with two treatments of transscleral iontophoresis given 24 and 48 hours after the intravitreal injection (group 3). Treatment was initiated 16, 24, or 48 hours after the induction of infection. For each interval from infection to treatment, there was a lower bacterial count and a higher rate of sterilization in the eyes in group 3 than in group 2; both treated groups had better outcomes than the untreated controls. These data suggest that transscleral iontophoresis could be clinically useful as a supplement to intravitreal injection for a refractory type of endophthalmitis such as that caused by Pseudomonas aeruginosa.
Animals↗
Dose response of experimental Pseudomonas endophthalmitis to ciprofloxacin, gentamicin, and imipenem: evidence for resistance to "late" treatment of infections.
Single intravitreal doses of ciprofloxacin, gentamicin, or imipenem were administered to rabbits with pseudomonas endophthalmitis for determination of the maximally effective dose. Treatment was given 24 hr ("early") or 48 hr ("late") after infection. With early treatment the dose-response relationship between the drug concentration and the diminution in bacterial counts in the vitreous humor was linear with all three drugs. By contrast, with late treatment the same vitreal concentrations had no significant effect on bacterial counts. The failure of late treatment was not due to an increased rate of clearance of drugs from the eyes and could not be reproduced with a similar bacterial inoculum in vitro. Bacteria cultured from treated eyes were fully sensitive when plated directly onto drug-containing agar. The poor bactericidal effect of late treatment may in part be related to transient phenotypic alterations in the bacteria in response to changes in the environment of infection such as hypoxia, low pH, and exhaustion of critical bacterial nutrients.
Animals↗