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Results for “Bacterial keratitis”

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At least 19 recordsLinked to original sources
PubMed1979

Experimental bacterial keratitis in neutropenic guinea pigs: polymorphonuclear leukocytes in corneal host defense.

Quantitative techniques were used to determine the relative concentrations of viable bacteria and polymorphonuclear leukocytes (PMNs) in the corneas of neutropenic and non-neutropenic guinea pigs with experimental bacterial keratitis induced with three strains of Pseudomonas aeruginosa. Neutropenia was produced by whole-body X-irradiation 1 week before infection. Significantly greater numbers of bacteria were present in the cornea of neutropenic animals 48 h after infection than were present in the corneas of non-neutropenic animals. The same was true 24 and 48 h after infecting animals with Staphylococcus aureus. Examination of histological sections showed that fewer PMNs were present in the corneas of infected neutropenic animals than in the corneas of infected non-neutropenic animals. Radiolabeling of PMNs confirmed a significant reduction in PMN concentration in the corneas of infected neutropenic animals. Tears and the corneal epithelium appear to be the most important elements protecting the cornea against local invasion by bacteria. However, once bacterial keratitis is established, PMNs play a role in limiting bacterial multiplication.

Animals↗
PubMed1976

Quantitation of bacterial infection and antibiotic effect in the cornea.

We report an experimental model that allows objective quantitation of bacterial keratitis. The model permits direct measurement of the number of viable organisms in the cornea after varying periods of in vivo growth. The size of the inoculum used to produce the corneal infection is critical, and the experimental organism must be standardized for its growth characteristics in the cornea. The end point is an objective one, productive of numerical data that can be subjected to statistical analysis. The findings are highly reproducible and the system is sufficiently sensitive to indicate the ability of a topically administered antibiotic to reduce the number of viable organisms in the cornea of an outbred rabbit population.

Administration, Topical↗
PubMed1978

Experimental Bacteroides fragilis keratitis.

To determine the corneal pathogenicity of certain anaerobic bacteria, Bacteroides fragilis keratitis was induced in rabbits by the intrastromal inoculation of 10' viable organisms. All eyes inoculated developed central abscesses within 24 hours. Abscesses persisted and became vascularized in two of three eyes that were observed for two weeks, as demonstrated both clinically and histologically. Eyes inoculated superficially with live organisms or intrastromally with solutions of dead organisms did not develop inflammatory lesions. Anaerobically incubated blood agar plates and thioglycollate broth were equally efficient in recovering organisms, although longer incubation times were occasionally necessary to recover organisms from broth cultures. Bacteroides fragilis and other anaerobic bacteria should be considered in the differential diagnosis of bacterial keratitis, and specific methods should be used to recover these organisms.

Abscess↗
PubMed1978

Scleral ring as template for corneoscleral graft.

A 19-year-old woman sustained a corneal laceration in her right eye. After bacterial keratitis was treated by antibiotics and a conjunctival flap, she developed a corneoscleral ectasia. We used a 15-mm diameter scleral ring as a template for corneoscleral graft. We obtained uniform donor and host buttons by suturing the ring alternately to donor and host eyes. One year postoperatively, the patient had a retrograft fibrous membrane with corneal edema, a visual acuity of R.E.: 6/60 (20/200), and intraocular pressure of 16 mm Hg.

Adult↗
PubMed1975

Conjunctival sensitivity in pathological cases, with simultaneous measurement of corneal and lid margin sensitivity.

A total of 209 pathological eyes each had 17 localities tested for sensitivity (cornea, caruncle, upper and lower lid margins (centrally, medially and laterally), and corresponding localities on the palpebral conjunctiva, and upper and lower halves of the bulbar conjunctiva). Reduced conjunctival sensitivity is seen in pemphigoid (excluding the lid margin) in contact lens wearers, at sites of nerves transected during operation and in rare cases of infectious conjunctivitis. Isolated corneal hypaesthesia is seen in bacterial or fungal keratitis. In herpes, the hypaesthesia extends over the bulbar conjunctiva, in zoster, over wider areas (including the lid margin). The sensitivity is normal in keratoconjunctivitis sicca and chronic conjunctivitis. In neurological diseases the hyposensitivity could include the cornea, conjunctiva and lid margin. The conclusion is drawn that a study of the conjunctivo-corneal sensitivity can give differential diagnostic information, provided the normal sensitivity range is known. This has been set out in a Table in 10-year age groups.

Adult↗
PubMed1978

[Considerations on the meta-herpetic keratitis (author's transl)].

The meta-herpetic keratitis is clinically characterized by the occurrence of a parenchymatous keratitis due to iterative herpetic corneal wounds. The rupture of the Bowman membrane which makes such a deep wound possible is performed by an enzyme: collagenase. This parenchymatous keratitis is rarely due to an extension of the viral infection. Most often it has an immunologic origin. It is a disciform keratitis due to a viral allergy, or a polymorphic keratitis connected with a bacterial, often tubercular, origin. In this case, one always notices a characteristic sugar tongs like composite limbic vascularization. Recovery can only be obtained by a specific desensitization.

Antibodies, Bacterial↗
PubMed2026

wbp-encoded LPS O-antigen architecture as a prognostic and therapeutic target in Pseudomonas aeruginosa keratitis.

BACKGROUND: Pseudomonas aeruginosa (P. aeruginosa) keratitis can progress rapidly to vision-threatening disease, even with intensive therapy. Virulence-associated genes are key determinants of ocular-surface pathogenesis. We therefore sought to develop a composite wbp-exo genotyping framework for risk stratification and to guide wbp-dependent, LPS-directed, levofloxacin-polymyxin B (LVX-POL) combination therapy for high-risk corneal infections. METHODS: A well-characterised clinical P. aeruginosa keratitis cohort was integrated with whole-genome sequencing. Based on comprehensive virulence-gene identification and annotation, the relationship between strain-level genetic features and clinical prognosis was analysed. The differences between WBP1 strains and WBP2 strains in adhesion, invasion, and biofilm formation in corneal epithelial cells were further evaluated. To establish biological plausibility, wbp genotypes were correlated with LPS O-antigen electrophoretic profiles and in vivo corneal inflammatory phenotypes in murine infection, including the observation of leucocyte recruitment and cytokine responses. To further confirm the key role of wbp gene status and LPS O-antigen in pathogenicity, wbpL knockout and reconstitution strains were constructed. Their appearances in vitro and in vivo were evaluated. Finally, a mechanistic rationale for an LPS-directed LVX-POL regimen was tested in a high-risk WBP1 P. aeruginosa murine keratitis. FINDINGS: Whole-genome sequencing was performed on 46 clinical P. aeruginosa isolates and identified an average of 332 virulence- and fitness-associated genes per strain. The exo and wbp gene families were significantly associated with patient prognosis. A fusion model (AUC = 0.86) outperformed single-gene-family models (EXO: 0.66; WBP: 0.72) for predicting clinical outcomes. Intact wbp cassettes were enriched in poor-outcome isolates, and electrophoretic LPS profiles indicated that WBP1 strains produce highly polymerised O-antigen associated with sustained neutrophil recruitment and cytokine production. Murine experiments further implicated wbp genes in clinical pathogenesis, showing stronger immune responses and higher expression of TLR4, MyD88, TRAF6, p65, p-p65, IL-6, TNF-α, and IL-1β throughout the inflammatory course. After knocking out wbpL gene, the WBP1 strain got stronger in biofilm formation and adhesion but weaker in inflammation and ocular surface survival. In the high-risk WBP1 P. aeruginosa keratitis model, LVX-POL combinations achieved complete ulcer resolution and markedly improved stromal infiltration and hypopyon, outperforming LVX monotherapy. INTERPRETATION: The wbp gene family was identified as a key genetic factor that contributes to the LPS O-antigen structure, inflammatory intensity, bacterial ocular surface survival and poor prognosis in P. aeruginosa keratitis. A WBP1-targeted, LPS-directed LVX-POL regimen was proposed as a mechanistically informed option for high-risk strains. FUNDING: This research was supported by Beijing Public Health High-level Talent Training Program (Phase III-03-14), Prevention and Control of Emerging and Major Infectious Diseases-National Science and Technology Major Project (2026ZD01909300) and Beijing Natural Science Foundation "QiYan" Undergraduate Research Fund (QY26496).

Pseudomonas aeruginosa↗
PubMed1979

Experimental Pseudomonas keratitis in guinea-pigs: therapy of moderately severe infections.

We have previously shown that antibiotic therapy of experimental Pseudomonas keratitis was more effective in early moderate infections than in late severe infections. The purpose of this study was to determine the relative efficacies of various drugs, routes, and vehicles in the treatment of moderately severe infection. As in the late severe infections, the most consistently effective regimen was an aminoglycoside applied topically in solution. No synergistic or additive effect was observed with a combination of aminoglycoside given topically and a penicillin given intramuscularly. Topical therapy with antibiotic in ointment was less effective than topical therapy with antibiotic in solution.

Administration, Topical↗
PubMed1979

Topical antibiotic therapy of Pseudomonas aeruginosa keratitis.

The in vivo antibacterial effectiveness in the rabbit cornea of several commercially available ophthalmic antibiotic preparations was determined against a single strain of Pseudomonas aeruginosa isolated from a human corneal ulcer. Each antibiotic was instilled topically at hourly intervals, and the number of residual viable organisms in the cornea subsequently was ascertained. In vivo measurements correlated well with in vitro data and with generally held clinical impressions. Three antibiotics, gentamicin sulfate, polymyxin B sulfate, and colistin sulfate, suppressed corneal growth of P aeruginosa in commercially available concentrations. Gentamicin was slightly more effective than polymyxin B; both drugs were substantially more effective than colistin. Formulations of gentamicin and polymyxin B containing approximately four times the quantity of drug found in commercial preparations eliminated this P aeruginosa strain from the cornea much more rapidly than did the commercial preparations.

Administration, Topical↗
PubMed1979

Nocardia asteroides keratitis.

Nocardia asteroides has been reported as the cause of keratitis in only 7 cases and of other ocular disease in another 12 cases. We report a case of N. asteroides keratitis that presented 3 weeks after rural trauma and progressed despite trials of appropriate antibiotics. Seven weeks after the origianl injury a successful conjunctival flap was placed over the cornea. The morphology and the sensitivity testing of N. asteroides to antibiotics appears necessary before reliable information can be obtained for clinical use. Moreover, our case did not show the relatively benign course of other reported cases of nocardia keratitis.

Adolescent↗