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Biomedical subjects

Philip A Thomas

Publications and source records attributed to Philip A Thomas.

18 recordsLinked to original sources
PubMed2006

Microbial keratitis at extremes of age.

PURPOSE: To study the risk factors, clinical presentation, response to treatment and outcome of microbial keratitis occurring in patients at extremes of age (ie, children and the elderly) and to compare them with microbial keratitis affecting the general adult population. METHODS: In this prospective, nonrandomized, analytical clinical study, all patients presenting with microbial keratitis and undergoing microbiological workup over a 1-year period were evaluated using a dedicated corneal ulcer protocol. Patients were divided into 3 groups based on age: (1) pediatric group if the age was 16 years or younger, (2) elderly group if the age was 65 years or older, and (3) control group if the age was between 17 and 64 years. Features studied included microbiological profile, predisposing factors, clinical presentation, response to treatment, and final visual outcome. RESULTS: A total of 269 eyes of 269 patients were studied (26 in the pediatric group, 55 in the elderly group, and 188 in the control group). Culture positivity rates were similar in all the groups. The elderly and control groups had a similar incidence of fungal and bacterial keratitis, but the pediatric group had a significantly lower incidence of fungal keratitis (P = 0.001). Trauma was the most common predisposing factor in all groups. Elderly patients tended to present with a higher incidence of central ulcers (P = 0.04), severe ulcers (P = 0.04), and poor visual acuity (P = 0.003) as compared with the control group. The percentage of ulcers healing with medical treatment alone was significantly more in the pediatric group (P = 0.004), while the incidence of poor visual outcome was greater in the elderly group (P = 0.006) as compared with the control group. CONCLUSIONS: Microbial keratitis in pediatric patients is more likely to be of bacterial etiology, and nonsevere ulcers in this age group have a better chance of resolution with medical therapy alone when compared with that in the general adult population. Conversely, elderly patients with microbial keratitis tend to present with severe, central ulcers with a significant risk of having a poor visual outcome.

Adolescent↗
PubMed2005

Outcome analysis of cataract surgery following therapeutic keratoplasty.

PURPOSE: To assess the results of cataract surgery, in terms of visual outcome and effect on graft survival, in eyes that have previously undergone therapeutic penetrating keratoplasty for infective keratitis. METHODS: Case records of patients who had undergone cataract surgery alone (group A) or in combination with regrafting (group B) following initial therapeutic penetrating keratoplasty between January 2000 and December 2001 were reviewed retrospectively. Main outcome measures studied were visual acuity, astigmatism, and effect of the cataract surgery on graft survival. Results were compared with eyes undergoing cataract surgery after optical keratoplasty and between eyes in groups A and B. RESULTS: Frequency of cataract surgery after therapeutic keratoplasty was significantly greater than that following optical keratoplasty [68 (52%) versus 47 (21%); P<0.001]. Fifty-eight eyes of 58 patients undergoing cataract surgery after therapeutic penetrating keratoplasty were analyzed in detail. Mean follow-up period was 8.9 months (+/-7.6 months). Thirty eyes underwent cataract surgery alone (group A), and 28 eyes underwent cataract surgery with regrafting (group B). Eyes that had undergone therapeutic keratoplasty were significantly more likely to have opaque grafts requiring regrafting at the time of cataract surgery than eyes that had undergone optical keratoplasty [28 (48.3%) versus 5 (10.6%); P<0.001]. Incidence of graft failure after cataract surgery did not differ significantly in eyes that had undergone therapeutic or optical keratoplasty. Final visual acuity at last follow-up was 6/12 or better in 25 eyes (43%). There were no significant differences between eyes in groups A and B in terms of final visual acuity, astigmatism, or graft failure rates. CONCLUSIONS: Visual results of cataract surgery following therapeutic keratoplasty are comparable to those following optical keratoplasty. Combining a repeat keratoplasty for a failed graft with the cataract surgery does not significantly affect the final outcome.

Adolescent↗
PubMed2005

Comparison of topical itraconazole 1% with topical natamycin 5% for the treatment of filamentous fungal keratitis.

PURPOSE: To compare the clinical efficacy of itraconazole 1% eyedrops with a standard therapy regimen (natamycin 5% eyedrops) for topical monotherapy of fungal keratitis. METHODS: Patients presenting with suspected uniocular microbial keratitis over a period of 12 months (January to December 2002) underwent detailed clinical examination and microbiological investigation. One hundred consecutive patients with direct smear- and/or culture-proven fungal keratitis were enrolled in the study after obtaining informed consent. The ulcers were categorized as severe or nonsevere. The first 50 consecutive patients received primary therapy with topical natamycin hourly, and the next 50 consecutive patients received topical itraconazole hourly. The primary efficacy criteria were the physician's judgment of clinical success, cure rate, and the rate of treatment failure. RESULTS: The diagnosis of fungal keratitis was established by positive microscopy and culture findings in 88 patients and by positive microscopy alone in 12 patients. Species of Fusarium, Aspergillus, and Curvularia were the principal isolates. Thirty-six (72%) of 50 patients (28 of 37 with nonsevere keratitis and 8 of 13 with severe keratitis) showed a favorable response to primary natamycin therapy (mean duration, 20.5 days), while 30 (60%) of 150 patients (25 of 38 with nonsevere keratitis and 5 of 12 with severe keratitis) exhibited a favorable response to primary itraconazole therapy (mean duration, 23.1 days). In keratitis due to Fusarium spp, 19 (79%) of 24 patients showed a favorable response to natamycin, which was significantly greater than the 8 (44%) of 18 patients who showed a favorable response to itraconazole (P < 0.02). However, no such difference was evident in keratitis due to Aspergillus spp or Curvularia spp; in keratitis due to Aspergillus spp, favorable responses were noted in 6 (54.5%) of 11 patients receiving natamycin and 5 (50%) of 10 patients receiving itraconazole, while in keratitis due to Curvurlaria spp, such responses occurred in both patients receiving natamycin and in 8 (89%) of 9 patients receiving itraconazole. Both antifungal formulations were generally well tolerated with no obvious adverse effects. CONCLUSIONS: Topical natamycin should continue to be considered as the treatment of choice for filamentous fungal keratitis; when natamycin is unavailable, topical itraconazole therapy could be used, particularly if the infections are due to Aspergillus or Curvularia spp.

Administration, Topical↗
PubMed2004

Keratitis due to a coelomycetous fungus: case reports and review of the literature.

PURPOSE: To describe a series of 7 patients with ulcerative keratitis caused by species of Colletotrichum, which are coelomycetous fungal pathogens. METHODS: The patients presented with keratitis of varying degrees of severity. Multiple scrapes from the corneal lesions of 6 of the 7 patients were used for microbiological investigations by a standard protocol. In the seventh patient, scraping was not performed due to the presence of deep infiltration and a descemetocele at presentation. All 7 patients were hospitalized and treatment was initiated with topical applications of natamycin (5%) and ciprofloxacin (0.3%) every hour and cyclopentolate (1%) drops 3 times daily. An emergency therapeutic penetrating keratoplasty was performed after 48 hours in the patient who had presented with a descemetocele and for another patient whose keratitis did not respond to 10 days of medical therapy. RESULTS: The corneal samples of all 7 patients yielded significant growth of filamentous fungi in culture. On the basis of macroscopic and microscopic characteristics, the fungal isolates were identified as Colletotrichum spp. Corneal lesions completely resolved with medical therapy alone in 5 patients. In the 2 patients who had undergone therapeutic penetrating keratoplasty, the infection was eradicated and the corneal graft remained clear even after several months of follow-up. CONCLUSION: Colletotrichum spp may be more frequent causes of keratitis than previously thought. Keratitis due to Colletotrichum spp frequently responds to medical therapy alone, although surgery may be indicated in a small proportion of patients.

Adolescent↗
PubMed2004

Trimethoprim-sulphamethoxazole therapy in Nocardia keratitis.

PURPOSE: To describe the clinical features, microbiological features and treatment outcome of nine patients with Nocardia keratitis treated with topical trimethoprim- sulphamethoxazole drops. METHODS: Retrospective review of nine patients with culture-proven Nocardia keratitis. RESULTS: Nine patients with Nocardia keratitis were treated with topical trimethoprim-sulphamethoxazole drops. The average duration of treatment was 25 +/- 9 days. Five of the nine patients presented with superficial ulcers with margins studded with yellowish white discrete pinhead sized infiltration; the other four patients had deep stromal infiltration. Complete healing of the ulcer was achieved in six out of the nine patients with topical trimethoprim- sulphamethoxazole alone or in combination with ciprofloxacin 0.3% eye drops. CONCLUSION: Topical application of trimethoprim-sulphamethoxazole appears to be effective therapy for superficial keratitis due to Nocardia.

Adolescent↗
PubMed2004

Comparison of in vitro characteristics of and experimental lesions produced by a clinical and an environmental isolate of Aspergillus flavus.

In the present study, two strains of Aspergillus flavus (one from a human corneal ulcer and one from the environment) were found to be strikingly similar in vitro in terms of thermotolerance, inability to grow in an anaerobic environment and in secreting proteinases; however, one obvious difference was that the clinical isolate produced 120 ppb of aflatoxin B1 in glucose salt medium while the environmental isolate did not produce this toxic metabolite. Alterations in the activities of acid phosphatase (ACP), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and glutathione-S-transferase were observed in the liver, kidney and serum in an experimental rat model, irrespective of whether the animal had been challenged with the clinical isolate or the environmental isolate of A. flavus. In rats that had been challenged with the clinical isolate, a significant decrease in the activity of kidney ALP was noted, whereas in rats that had been challenged with the environmental isolate, the reverse was observed. While these differential alterations may have occurred due to differences in the toxin-producing ability of the two isolates, further investigation is warranted to clarify whether other phenotypic, or genotypic, differences are also involved.

Acid Phosphatase↗
PubMed2003

Municipal solid waste in situ moisture content measurement using an electrical resistance sensor.

Moisture content (MC) is a crucial parameter for degradation of solid waste in landfills. Present MC measurement techniques suffer from several drawbacks. A moisture sensor for measurement of in situ moisture content of solid waste in landfills was developed. The sensor measures the electrical resistance across the granular matrix of the sensor, which in turn can be correlated to moisture content. The sensor was also equipped with a thermocouple and tubing that permits simultaneous measurement of temperature and gas sampling. The electrical conductivity of the surrounding moisture and the temperature in the matrix both affect the resistance measurements. This paper describes the results of laboratory experiments designed to select the appropriate granular media particle size, measure the influence of moisture electrical conductivity and temperature, and develop calibration relationships between measured resistance and gravimetrically determined moisture content. With a few limitations, the sensor is able to detect MC of solid waste under conditions allowing moisture movement into the sensor. The application of this technique shows promise for use in bioreactor landfills where high moisture contents are expected and desired.

Biodegradation, Environmental↗
PubMed2003

Pneumococcal keratitis: a clinical profile.

AIM: To study the clinical features of pneumococcal keratitis and response to ciprofloxacin therapy. METHODS: A retrospective analysis was undertaken of 58 patients with culture-proven pneumococcal keratitis seen over a period of 2 years. RESULTS: Pneumococcal keratitis accounted for 33.3% of bacterial keratitis. Most cases presented with non-severe keratitis (77.5%). Co-existing sac pathology was more frequent in pneumococcal ulcers as compared to non-pneumococcal bacterial ulcers (50%vs 9%, P < 0.001). Characteristic clinical features enabling an accurate clinical diagnosis were found in 27.5% and lanceolate diplococci on Gram's stain were identified in 76% of cases. In vitro testing showed a high susceptibility to cephazolin and ciprofloxacin. All patients received ciprofloxacin as first-line therapy. Eighty per cent responded well with complete healing of the ulcer. A second drug was required in 8.5%. CONCLUSION: Ciprofloxacin therapy can be effective in the treatment of pneumococcal keratitis.

Adult↗
PubMed2003

Subretinal fluid analysis in the diagnosis of choroidal tuberculosis.

BACKGROUND: Diagnosis of intraocular tuberculosis is often difficult. A choroidal granulomalike lesion suspected to be the result of tuberculosis could be of other inflammatory, infective, or neoplastic causes. We report two cases in which a choroidal granuloma with exudative retinal detachment was diagnosed as tuberculosis by the detection of acid-fast bacilli in subretinal fluid. METHODS: Interventional case series. RESULTS: Two female patients had choroidal granulomas with surrounding exudative retinal detachment. Detailed laboratory investigations were unhelpful in diagnosis, and the patients' conditions worsened with systemic steroid therapy. Subretinal fluid was tapped and revealed acid-fast bacilli and grew Mycobacterium tuberculosis on culture. CONCLUSION: Subretinal fluid analysis can help in the detection of tuberculous granuloma and facilitate successful management.

Adult↗
PubMed2003

Current perspectives on ophthalmic mycoses.

Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.

Antifungal Agents↗
PubMedDate not supplied

Bilateral Pseudomonas keratitis without predisposing factors.

Bilateral keratitis usually occurs in predisposed individuals such as contact lens wearers, those suffering from malnutrition and immunodeficiency or patients undergoing bilateral refractive corneal surgery. We report a 30-year-old man without any obvious predisposing factors who presented with complaints of pain and decreased vision in both eyes. Examination revealed corneal ulcers in both eyes, which on microbiological culture grew Pseudomonas aeruginosa. The patient underwent a therapeutic keratoplasty in the right eye while the left eye was managed medically. Bilateral Pseudomonas keratitis can develop in the absence of any obvious predisposing factors.

Adult↗