Risk factors for treatment outcome of suspected microbial keratitis. Ofloxacin Study Group

Evaluation of photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) in feline infectious keratitis-patient demographics, treatment protocols, risk factors, and treatment outcome: a retrospective study

OBJECTIVES

To describe patient demographics and treatment protocols in a population of feline patients undergoing photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) as an adjunctive treatment for infectious keratitis. Furthermore, to determine the proportion of PACK-CXL treatment success in the population studied, explore risk factors for treatment failure, and provide recommendations for future PACK-CXL clinical studies.

MATERIALS AND METHODS

Records from four veterinary ophthalmology practices were reviewed to identify eligible patients and extract data. Recorded variables included patient-related factors, ocular examination findings, PACK-CXL protocol parameters, and treatment outcome.

RESULTS

Records for 153 cats (154 eyes) were included. Median age in the treatment success group was 8 years (interquartile range (IQR) 4-12), with a median ulcer depth of 30% (IQR 30-40). Median age in the treatment failure group was 10.5 years (IQR 4.75-12) with a median ulcer depth of 45.9% (IQR 30-75). Persian cats were the most represented brachycephalic breed (52 out of 64 cats). Modified PACK-CXL protocols were used, including fast energy delivery (134 eyes), and increased fluence (52 eyes). The overall proportion of success was 88% (95% CI 84-93), which was variable between clinics. Eighty-two of 89 mesocephalic cat eyes (92%), and 54 of 65 brachycephalic cat eyes (83%) were classified as treatment successes.

CONCLUSIONS

PACK-CXL appeared to be a useful, adjunctive therapeutic modality for the treatment of infectious keratitis in the feline patient population presented here. Brachycephalic cats, older cats, and those with deeper ulcers may be at increased risk for treatment failure.

Validation of the C-DU(KE) Calculator as a Predictor of Outcomes in Patients Enrolled in Steroids for Corneal Ulcer and Mycotic Ulcer Treatment Trials

PURPOSE

The aim of this study was to validate the C-DU(KE) calculator as a predictor of treatment outcomes on a data set derived from patients with culture-positive ulcers.

METHODS

C-DU(KE) criteria were compiled from a data set consisting of 1063 cases of infectious keratitis from the Steroids for Corneal Ulcer Trial (SCUT) and Mycotic Ulcer Treatment Trial (MUTT) studies. These criteria include corticosteroid use after symptoms, visual acuity, ulcer area, fungal etiology, and elapsed time to organism-sensitive therapy. Univariate analysis was performed followed by multivariable logistic regressions on culture-exclusive and culture-inclusive models to assess for associations between the variables and outcome. The predictive probability of treatment failure, defined as the need for surgical intervention, was calculated for each study participant. Discrimination was assessed using the area under the curve for each model.

RESULTS

Overall, 17.9% of SCUT/MUTT participants required surgical intervention. Univariate analysis showed that decreased visual acuity, larger ulcer area, and fungal etiology had a significant association with failed medical management. The other 2 criteria did not. In the culture-exclusive model, 2 of 3 criteria, decreased vision [odds ratio (OR) = 3.13, P < 0.001] and increased ulcer area (OR = 1.03, P < 0.001), affected outcomes. In the culture-inclusive model, 3 of 5 criteria, decreased vision (OR = 4.9, P < 0.001), ulcer area (OR = 1.02, P < 0.001), and fungal etiology (OR = 9.8, P < 0.001), affected results. The area under the curves were 0.784 for the culture-exclusive model and 0.846 for the culture-inclusive model which were comparable to the original study.

CONCLUSIONS

The C-DU(KE) calculator is generalizable to a study population from large international studies primarily taking place in India. These results support its use as a risk stratification tool assisting ophthalmologists in patient management.

Evaluation of risk factors for treatment failure in canine patients undergoing photoactivated chromophore for keratitis - corneal cross-linking (PACK-CXL): a retrospective study using additive bayesian network analysis

BACKGROUND

Infectious keratitis is a common ophthalmic condition in canine patients. Sequelae can include keratomalacia and corneal perforation, a vision threatening outcome. Photoactivated chromophore for keratitis - corneal cross-linking (PACK-CXL) is a non-surgical, adjunctive treatment method for infectious keratitis. The goal of this retrospective, multicenter study was to determine risk factors for treatment failure following PACK-CXL in canine patients suffering from suspected infectious keratitis. Medical records from four veterinary ophthalmology services were reviewed, and information related to patient demographics, ophthalmic findings, the PACK-CXL protocol used, and epithelialization time was collected and analyzed. Due to the potential for intervariable relationships, an additive Bayesian network (ABN) analysis was performed to evaluate these complex relationships.

RESULTS

Records for 671 eyes (668 dogs) were included in the analysis. Based on the ABN, in the population included here, patients who underwent an accelerated PACK-CXL protocol were less likely to experience treatment failure versus patients treated with a slow protocol. Mutual dependencies between exposure variables were identified by ABN, which would have been overlooked using classical regression. Corneal re-epithelialization time was shortened following PACK-CXL combined with topical medical therapy compared to PACK-CXL alone.

CONCLUSIONS

No risk factors associated with treatment failure were identified in the population included in the present study. Canine patients may benefit from the use of accelerated PACK-CXL protocols, especially when combined with topical antibiotics and anti-collagenolytic therapy. The reasons for this apparent positive impact on treatment outcome remain unclear.

Clinical comparative analysis of culture-proven bacterial keratitis according to prior topical steroid use: a retrospective study in a tertiary referral center of South Korea

This study analyzed the clinical characteristics of patients exposed to topical steroids before bacterial keratitis diagnosis (the prior topical steroid use, PS group), and compared these with those of the non-exposed group (the no prior topical steroid use, NPS group). We retrospectively analyzed 194 patients (PS, 34; NPS, 160) with culture-proven bacterial keratitis between 2007 and 2016. The microbiological profiles, epidemiology, predisposing factors, clinical characteristics, and treatment outcomes of PS and NPS were compared, and the risk factors for surgical intervention were evaluated. Pseudomonas spp. and Staphylococcus spp. were the most common isolates in PS and NPS, respectively, and no significant difference in the strain distribution between the two groups were observed. Significant differences were observed between PS and NPS for previous ocular surface disease (41.2%: 23.8%), initial BCVA < 0.1 (70.6%: 49.4%), epithelial defect size ≥ 5 mm2 (64.7%: 41.2%), epithelial healing time > 14 days (55.9%: 37.3%), and surgical intervention (23.5%: 8.8%). Prior topical steroid use, strong steroid use, and long-term steroid use groups were included in significant risk factors for surgical intervention. Previous exposure to topical steroids before the diagnosis of bacterial keratitis was associated with a worse initial clinical presentation and treatment outcomes. Additional multicenter studies should be conducted in the future.

C-DU(KE) Calculator: A Clinical Tool for Risk Stratification in Infectious Keratitis

PURPOSE

The aim of this study was to identify characteristics of infectious keratitis predictive of poor outcome to develop a web-based predictive calculator.

METHOD

A retrospective chart review was performed at the Duke Eye Center. Two hundred fifteen adult patients with culture-proven infectious keratitis presenting between January 1, 2016, and December 31, 2020, were separated into a derivation set (136 patients, 53 positives; 83 controls) and a temporal validation set (79 patients, 26 positives; 53 controls). The poor outcome group consisted of patients requiring penetrating keratoplasty for visually significant scarring, penetrating keratoplasty for ulcer progression, or evisceration/enucleation for endophthalmitis. Univariable analysis was performed followed by stepwise multivariable logistic regression to obtain a predictive model in the derivation data set. Culture-naïve and postculture models were constructed. Discrimination and calibration were assessed using the area under the curve (AUC) and calibration plots, respectively.

RESULTS

The culture-naïve model consisted of corticosteroid drop use postsymptom onset [Odds Ratio (OR) = 2.3, P = 0.054], decreased vision (OR = 2.4, P = 0.001), and increased ulcer area (OR = 1.017, P = 0.017). The postculture model additionally included fungal keratitis (OR = 5.4, P = 0.006) and elapsed time from symptoms to organism-sensitive therapy (OR = 1.027, P = 0.014). The models were summarized by the acronym C-DU(KE). The AUCs for the culture-naïve model were 0.794 in the derivation set and 0.850 in the validation set. The AUCs for the postculture model were 0.898 in the derivation set and 0.946 in the validation set. Calibration plots indicated goodness of fit in the data sets for both models. The calculator was deployed under the URL: https://duke-eye-calculator.shinyapps.io/Corneal_Ulcers/ .

CONCLUSIONS

The C-DU(KE) calculator permits a data-driven prediction of outcome in infectious keratitis that can supplement clinical judgment.

Utility of investigation for suspected microbial keratitis: a diagnostic accuracy study

PURPOSE

The true disease status of a population with suspected microbial keratitis (MK) cannot be verified. There is not an accurate (gold) reference standard to confirm infection and inter-test comparisons of sensitivity and specificity therefore lead to bias with questionable estimates of test utility. We present an alternative method to report results.

METHODS

We used a decision to treat as the definition for MK. We retrospectively compared the results of corneal culture and polymerase chain reaction (PCR) as these are objective tests available for the three principal groups of pathogens. We then estimated the potential contribution of positive results, either alone or in combination, to support the working diagnosis.

RESULTS

We included 2021 (77.4%) eyes with suspected bacterial keratitis, 365 (14.0%) with suspected acanthamoeba keratitis, and 226 (8.6%) with suspected fungal keratitis, all treated between July 2013 and December 2019. In these groups, there were 51.6% positive culture and 6.5% positive PCR results for bacteria, 19.0% and 40.5% for acanthamoeba, and 28.3% and 15.0% for fungi. Between groups the differences in the proportions of positive results from culture and PCR was statistically significant (P < 0.001). The added benefit of PCR to the result of culture in identifying a potential pathogen was 1.4% for bacteria (P = 0.6292), 24.4% for acanthamoeba (P = 0.0001), and 5.8% for fungi (P = 0.3853).

CONCLUSIONS

For suspected MK a comparison of the test positivity rate is an easily comprehensible outcome measure of test utility.

Comparison of culture, confocal microscopy and PCR in routine hospital use for microbial keratitis diagnosis

AIMS

To evaluate the sensitivity and specificity of polymerase chain reaction (PCR), in vivo confocal microscopy (IVCM) and culture for microbial keratitis (MK) diagnosis.

METHODS

Retrospective review of PCR, IVCM and culture results for MK diagnosis at Moorfields Eye Hospital between August 2013 and December 2014.

RESULTS

PCR results were available for 259 MK patients with concurrent culture for 203/259 and IVCM for 149/259. Sensitivities and specificities with 95% confidence intervals [95% CI] were calculated for Acanthamoeba keratitis (AK) and fungal keratitis (FK), by comparison with culture, for both IVCM and PCR. For AK, FK and bacterial keratitis (BK) sensitivities were calculated, for each diagnostic method, by comparison with a composite reference standard (a positive result for one or more of culture, PCR or IVCM having a specificity of 100% by definition). For the latter, sensitivities with [95% CI] were: for AK, IVCM 77.1% [62.7-88.0%], PCR 63.3% [48.3-76.6%], culture 35.6 [21.9-51.2]; for FK, IVCM 81.8% [48.2-97.7%], PCR 30.8% [9.09-61.4%], culture 41.7% [15.2-72.3%]; for BK, PCR 25.0% [14.7-37.9%], culture 95.6% [87.6-99.1%].

CONCLUSION

IVCM was the most sensitive technique for AK and FK diagnosis but culture remains our gold standard for BK. These findings reflect results to be expected from service providers to UK ophthalmology units and demonstrates the need at our centre for ongoing diagnostic result audit leading to the potential to improve PCR diagnosis. Both FK and AK are now common in the UK; ophthalmology units need to have all these techniques available to optimise their MK management.

Bacterial keratitis: identifying the areas of clinical uncertainty

Bacterial keratitis is a common corneal infection that is treated with topical antimicrobials. By the time of presentation there may already be severe visual loss from corneal ulceration and opacity, which may persist despite treatment. There are significant differences in the associated risk factors and the bacterial isolates between high income and low- or middle-income countries, so that general management guidelines may not be appropriate. Although the diagnosis of bacterial keratitis may seem intuitive there are multiple uncertainties about the criteria that are used, which impacts the interpretation of investigations and recruitment to clinical studies. Importantly, the concept that bacterial keratitis can only be confirmed by culture ignores the approximately 50% of cases clinically consistent with bacterial keratitis in which investigations are negative. The aetiology of these culture-negative cases is unknown. Currently, the estimation of bacterial susceptibility to antimicrobials is based on data from systemic administration and achievable serum or tissue concentrations, rather than relevant corneal concentrations and biological activity in the cornea. The provision to the clinician of minimum inhibitory concentrations of the antimicrobials for the isolated bacteria would be an important step forward. An increase in the prevalence of antimicrobial resistance is a concern, but the effect this has on disease outcomes is yet unclear. Virulence factors are not routinely assessed although they may affect the pathogenicity of bacteria within species and affect outcomes. New technologies have been developed to detect and kill bacteria, and their application to bacterial keratitis is discussed. In this review we present the multiple areas of clinical uncertainty that hamper research and the clinical management of bacterial keratitis, and we address some of the assumptions and dogma that have become established in the literature.

Medical History, Clinical Features, Treatment Outcome and Its Predictors Among Infectious Keratitis Patients in Jimma University Medical Center, Southwest Ethiopia: Prospective Observational Study

BACKGROUND

Infectious keratitis is a major global cause of visual impairment and irreversible blindness among the corneal diseases. Its diagnosis and management remain getting challenge. The clinical and visual outcome remains poor in developing countries. The aim of this study was to determine treatment outcome and its predictors among patients with infectious keratitis.

METHODS

Prospective observational study was conducted among adult patients diagnosed with infectious keratitis at the Ophthalmology Department in Jimma University Medical Center from April 1 to September 30, 2019. The primary outcome indicator was response of the ulcer to empirical treatment. Ulcers that did not heal and required surgery had a poor outcome. Variables with a p-value of <0.25 were entered into a multivariate logistic regression model to determine the independent predictors of poor treatment outcome and variables with a p-value of <0.05 were considered statistically significant.

RESULTS

The research involved 131 adult patients. Eighty-seven (66.4%) were males. The mean age was 39.38 (±18.9) years. Eighty-three (63.4%) patients had poor treatment outcome. Mean length of hospital stay was 17.38 (±12.563) days. Poor visual outcome was observed among 71 (54.2%) participants. Evisceration was done for seven (5.3%) patients. Independent predictors of poor treatment outcome include perforation at admission (AOR=6.1, 95%CI: 1.5-25.1), presence of comorbidity (AOR=7.7, 95%CI: 2.16-27.3), poor adherence (AOR=5.3, 95%CI: 1.8-25.9), traditional medicine use (AOR=6.7, 95%CI: 1.8-25.4), ulcer depth >1/3 (AOR=7.6, 95%CI: 2.48-48.23) and farm workers (AOR=3.59, 95%CI: 1.09-11.77). Major complications occurred after admissions were perforation (14.5%), followed by endophthalmitis (7.63%) and corneal opacity (6.87%).

CONCLUSION AND RECOMMENDATION

Our study found high poor treatment outcomes and high poor visual outcomes. Presence of comorbidity, perforation at admission, traditional medicine use, working on a farm, poor adherence, and ulcer depth were the predictors of poor treatment outcome. This high poor outcome requires a nationwide interventional study and urgent intervention that may reach rural communities.

Laboratory Results, Epidemiologic Features, and Outcome Analyses of Microbial Keratitis: A 15-Year Review From St. Louis

PURPOSE

To evaluate the laboratory results and prognostic factors of poor clinical outcomes in microbial keratitis cases over 15 years at Saint Louis University.

DESIGN

Retrospective cohort and trend study.

METHODS

Microbiological and clinical information from culture-positive cases seen at Saint Louis University from 1999 to 2013 were reviewed retrospectively. Statistical analyses were used to determine microbiological and antibiotic susceptibility trends. Prognostic factors of poor clinical outcome from the literature were used to create multivariate regression models to describe our cohort.

RESULTS

Gram-positive organisms predominated (48%), followed by gram-negative organisms (34%) and fungi (16%). The most commonly isolated organism was Pseudomonas aeruginosa (21%). Oxacillin-resistant rates of Staphylococcus aureus and coagulase-negative staphylococci were 45% and 43%, respectively. Only the proportion of Pseudomonas changed significantly over time (P = .02). The only antibiotic found to lose efficacy over time was gentamicin for gram-positive organisms (P = .005). Multivariate logistic regression analyses revealed that major complications were associated with large ulcers (P < .006), fungal cases (P < .001), and comorbid ophthalmic conditions (P < .001). Poor healing was associated with large ulcers (P < .001) and fungal cases (P < .001). Lastly, poor visual outcome was associated with large ulcers (P < .01) and age ≥ 60 years (P < .02).

CONCLUSIONS

In the St Louis area, oxacillin-resistant organisms, Pseudomonas aeruginosa, and fungi are commonly recovered from microbial keratitis cases with a disproportionally high incidence. Hence, empiric antibiotic choice should reflect these trends. Special care needs to be taken for patients with large ulcers and fungal infections, as well as elderly patients with comorbid ophthalmic conditions, as these patients have worse clinical outcomes.

Comparison of clinical characteristics and antibiotic susceptibility between Pseudomonas aeruginosa and P. putida keratitis at a tertiary referral center: a retrospective study

BACKGROUND

To compare clinical characteristics and antibiotic susceptibilities in patients with Pseudomonas aeruginosa (PA) and P. putida (PP) keratitis at a tertiary referral center in South Korea.

METHODS

Forty-nine cases of inpatients with culture-proven PA and PP keratitis were reviewed retrospectively between January 1998 and December 2017. We excluded cases of polymicrobial infection. Epidemiology, predisposing factors, clinical characteristics, antibiotic susceptibilities, and treatment outcomes were compared between the PA and PP groups. The risk factors for poor clinical outcome were evaluated on the basis of the total cohort and analyzed using multivariate logistic regression.

RESULTS

A total of 33 eyes with PA keratitis and 16 eyes with PP keratitis were included. The mean age was 47.0 years in the PA group and 59.3 years in the PP group (p = 0.060). Differences were observed between the PA and PP groups in hypopyon (45.5% vs 6.3%, p = 0.006) and symptom duration (4.3 vs 9.5 days, p = 0.022). The most common predisposing factor for PA was wearing contact lenses (36.4%) and that for PP was corneal trauma (62.5%). No significant differences were observed in sex, previous topical steroid use, systemic disease, or duration of hospitalization between the two groups. The PA and PP groups both demonstrated good efficacy of colistin (both 100%), tobramycin (93.3%, 100%), ceftazidime (93.9%, 87.5%), and ciprofloxacin (96.6%, 87.5%). Imipenem (100% vs 81.3%, p = 0.030), piperacillin (96.6% vs 75%, p = 0.047), and ticarcillin (85% vs 0%, p < 0.001) showed significantly lower efficacy in the PP group than in the PA group. A poor clinical outcome was observed in 31.2% of the PA group and 37.5% of the PP group (p = 0.665). The risk factors for poor clinical outcome were previous ocular surface disease (odds ratio 10.79, p = 0.012) and hypopyon (odds ratio 9.02, p = 0.024).

CONCLUSIONS

The PA group was more closely associated with younger age, wearing contact lenses, shorter symptom duration, and hypopyon, whereas the PP group was more closely associated with elderly age, corneal trauma, and decreased efficacy of the beta-lactams. Clinical outcomes were not significantly different between the two groups. Previous ocular surface disease and hypopyon were the risk factors for poor clinical outcome.

Impression membrane for the diagnosis of microbial keratitis

PURPOSE

To evaluate a corneal impression membrane (CIM) for isolation of bacteria, fungi and acanthamoeba in suspected microbial keratitis.

METHODS

Consecutive patients presenting with suspected microbial keratitis were included. For each patient, samples were collected in a random order using a surgical blade and a 4-mm-diameter polytetrafluoroethylene CIM disc, and transported in brain heart infusion broth. Risk factors, best corrected visual acuity (BCVA), size, location, depth and healing time of the ulcer were recorded. The microbial isolation rate was used to compare sampling methods.

RESULTS

130 patients were included (mean age 62.6 years, SD 19.0). An antimicrobial had been used prior to presentation in 36 (27.7%) patients. Mean major and minor ulcer diameters were 2.1 mm (SD 2.0) and 1.6 mm (SD 1.7). Mean healing time was 12.4 days (SD 13.6). BCVA at presentation and following healing was 0.7 (SD 0.7) and 0.62 (SD 0.7) (p=0.34). There were 66 isolates (50.8%); 53 (40.8%) using a CIM and 35 (26.9%) using a blade (p=0.02). ITALIC! Staphylococcus aureus and coagulase-negative staphylococci were the commonest isolates. Isolation rate was not influenced by organism type, although in four cases ITALIC! Acanthamoeba spp. were isolated; three using CIM and one a blade.

CONCLUSIONS

In this study, the isolation of microorganisms from cases of suspected microbial keratitis was significantly higher using a CIM than a surgical blade. A CIM may be a useful alternative or addition for sample collection in microbial keratitis.

Topical corticosteroids as adjunctive therapy for bacterial keratitis

BACKGROUND

Bacterial keratitis is a serious ocular infectious disease that can lead to severe visual disability. Risk factors for bacterial corneal infection include contact lens wear, ocular surface disease, corneal trauma, and previous ocular or eyelid surgery. Topical antibiotics constitute the mainstay of treatment in cases of bacterial keratitis, whereas the use of topical corticosteroids as an adjunctive therapy to antibiotics remains controversial. Topical corticosteroids are usually used to control inflammation using the smallest amount of the drug. Their use requires optimal timing, concomitant antibiotics, and careful follow-up.

OBJECTIVES

The objective of the review was to assess the effectiveness and safety of corticosteroids as adjunctive therapy for bacterial keratitis. Secondary objectives included evaluation of health economic outcomes and quality of life outcomes.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2014), EMBASE (January 1980 to July 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to July 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 14 July 2014. We also searched the Science Citation Index to identify additional studies that had cited the only trial included in the original version of this review, reference lists of included trials, earlier reviews, and the American Academy of Ophthalmology guidelines. We also contacted experts to identify any unpublished and ongoing randomized trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that had evaluated adjunctive therapy with topical corticosteroids in people with bacterial keratitis who were being treated with antibiotics.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We found four RCTs that met the inclusion criteria of this review. The total number of included participants was 611 (612 eyes), ranging from 30 to 500 participants per trial. One trial was included in the previous version of the review, and we identified three additional trials through the updated searches in July 2014. One of the three smaller trials was a pilot study of the largest study: the Steroids for Corneal Ulcers Trial (SCUT). All trials compared the treatment of bacterial keratitis with topical corticosteroid and without topical corticosteroid and had follow-up periods ranging from two months to one year. These trials were conducted in the USA, Canada, India, and South Africa.All trials reported data on visual acuity ranging from three weeks to one year, and none of them found any important difference between the corticosteroid group and the control group. The pilot study of the SCUT reported that time to re-epithelialization in the steroid group was 53% slower than the placebo group after adjusting for baseline epithelial defect size (hazard ratio (HR) 0.47; 95% confidence interval (CI) 0.23 to 0.94). However, the SCUT did not find any important difference in time to re-epithelialization (HR 0.92; 95% CI 0.76 to 1.11). For adverse events, none of the three small trials found any important difference between the two treatment groups. The investigators of the largest trial reported that more patients in the control group developed intraocular pressure (IOP) elevation (risk ratio (RR) 0.20; 95% CI 0.04 to 0.90). One trial reported quality of life and concluded that there was no difference between the two groups (data not available). We did not find any reports regarding economic outcomes.Although the four trials were generally of good methodological design, all trials had considerable losses to follow-up (10% or more) in the final analyses. Further, three of the four trials were underpowered to detect treatment effect differences between groups and inconsistency in outcome measurements precluded meta-analyses for most outcomes relevant to this review.

AUTHORS' CONCLUSIONS

There is inadequate evidence as to the effectiveness and safety of adjunctive topical corticosteroids compared with no topical corticosteroids in improving visual acuity, infiltrate/scar size, or adverse events among participants with bacterial keratitis. Current evidence does not support a strong effect of corticosteroid, but may be due to insufficient power to detect a treatment effect.

Visual outcomes in treated bacterial keratitis: four years of prospective follow-up

PURPOSE

We described the change in visual acuity experienced by eyes successfully treated for bacterial keratitis.

METHODS

This was a prospective cohort study of a subset of study participants who had previously enrolled in the Steroids for Corneal Ulcers Trial (SCUT). All study participants had been diagnosed with culture-proven bacterial keratitis before enrollment in SCUT and subsequently were randomized to adjunctive topical corticosteroids or placebo. During SCUT, we monitored study participants at enrollment, 3 weeks, 3 months, and 12 months. We invited a subset to complete a comprehensive eye examination approximately 4 years after enrollment in SCUT. Certified refractionists assessed best spectacle-corrected visual acuity (BSCVA) using the same protocol at each study visit.

RESULTS

We examined 50 SCUT participants at 4 years after enrollment. Among those in this cohort, mean logMAR BSCVA at enrollment was 0.85 (Snellen equivalent, 20/160; 95% confidence interval [CI], 0.71-0.99). On average, visual acuity improved by 2.9 logMAR lines from enrollment to 3 weeks (P < 0.001), 1.2 lines from 3 weeks to 3 months (P = 0.002), and 0.8 lines from 3 to 12 months (P = 0.01). The BSCVA did not change significantly between 12 months and 4 years (0.04-line improvement, P = 0.88). After controlling for visual acuity at enrollment, BSCVA was not significantly different between the corticosteroid and placebo groups at 4 years (P = 0.53).

CONCLUSIONS

Cases of bacterial keratitis may continue to demonstrate improvements in visual acuity up to 12 months following diagnosis, but further improvements are unlikely. These findings may guide the appropriate timing of surgical intervention in these patients. (ClinicalTrials.gov number, NCT00324168.).

[Clinical and microbiological features of severe infectious keratitis during heatwaves]

PURPOSE

To study clinical and microbiological features of patients with severe microbial keratitis during a heatwave. To evaluate the links between disease severity, causative micro-organisms and temperature variation.

METHODS

Retrospective study of patients with microbial keratitis hospitalized in a referral center during the summer months (between June 1, 2009 and September 30, 2009), separated into two groups by date of hospitalization (heatwave vs non-heatwave). Prevalence and daytime temperatures were compared for data collected during the summers of 2009 (heatwave), 2008 (temperate) and 2003 (prolonged heatwave).

RESULTS

Thirty-three patients were hospitalized during the summer of 2009, with an average age of 51 years and an average stay of 15 days. The primary predisposing factor was the use of contact lenses (36%), followed by pre-existing corneal disease (15%) and systemic disease (15%). Prevalence of severe keratitis was higher in periods of heatwaves vs periods of no heatwaves (mean 9.8 patients vs 3.1, P<0.001). Best corrected visual acuity progressed from 1/30 at admission to 1/10 at 1 month after discharge (P<0.001). The most common bacteria identified were Gram-positive cocci (CNS 27%) and Pseudomonas (23%). Microbiological results were similar in the two groups. Similar variations between the prevalence of severe keratitis and daytime temperatures were found for the summer of 2009 as well as for the summers of 2008 and 2003.

CONCLUSIONS

There appears to be a link between climatic temperature variations and the prevalence of severe microbial keratitis.

Predictors of outcome in fungal keratitis

PURPOSE

To analyse predictors of clinical outcome in fungal keratitis.

METHODS

Data was collected during a prospective, randomized, controlled, double-masked clinical trial of treatment for fungal keratitis. Clinical features at presentation and demographics were collected at the enrollment visit for all patients. Pre-specified clinical outcomes included 3-month visual acuity and infiltrate/scar size, time to re-epithelialization, and corneal perforation. A separate multivariable model with each outcome as the dependent variable included all predictor variables.

RESULTS

Predictors for worse 3-month visual acuity include older age (P=0.024), worse presentation visual acuity (P<0.001), larger infiltrate size at presentation (P<0.001), and pigmented ulcer (P=0.030). Larger infiltrate size at presentation was a significant predictor of worse 3-month infiltrate/scar size (P<0.001). Larger epithelial defect size was a significant predictor of perforation (P=0.0013). Predictors of longer time to re-epithelialization include infiltrate size at presentation (P<0.001) and older age (P=0.025).

CONCLUSION

Ulcer severity at presentation is highly predictive of worse outcomes. Presentation of clinical characteristics such as baseline acuity and infiltrate scar can provide important information to clinicians about prognosis, and may help guide management and treatment decisions. Prevention of corneal ulcer remains important, as it is difficult to change the course of the ulcer once it has begun.

The steroids for corneal ulcers trial: study design and baseline characteristics

OBJECTIVES

To provide comprehensive trial methods and baseline data for the Steroids for Corneal Ulcers Trial and to present epidemiological characteristics such as risk factors, causative organisms, and ulcer severity.

METHODS

Baseline data from a 1:1 randomized, placebo-controlled, double-masked clinical trial comparing prednisolone phosphate, 1%, with placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and had been taking moxifloxacin for 48 hours. The primary outcome for the trial is best spectacle-corrected visual acuity at 3 months from enrollment. This report provides comprehensive baseline data, including best spectacle-corrected visual acuity, infiltrate size, microbiological results, and patient demographics, for patients enrolled in the trial.

RESULTS

Of 500 patients enrolled, 97% were in India. Two hundred twenty patients (44%) were agricultural workers. Median baseline visual acuity was 0.84 logMAR (Snellen, 20/125) (interquartile range, 0.36-1.7; Snellen, 20/50 to counting fingers). Baseline visual acuity was not significantly different between the United States and India. Ulcers in India had larger infiltrate/scar sizes (P = .04) and deeper infiltrates (P = .04) and were more likely to be localized centrally (P = .002) than ulcers enrolled in the United States. Gram-positive bacteria were the most common organisms isolated from the ulcers (n = 366, 72%).

CONCLUSIONS

The Steroids for Corneal Ulcers Trial will compare the use of a topical corticosteroid with placebo as adjunctive therapy for bacterial corneal ulcers. Patients enrolled in this trial had diverse ulcer severity and on average significantly reduced visual acuity at presentation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00324168.

Clinical aspects and prognosis of mixed microbial (bacterial and fungal) keratitis

PURPOSE

To investigate the predisposing factors, clinical presentations, treatment results, and prognosis of keratitis caused by mixed infectious agents (bacteria and fungi).

METHODS

This is a retrospective study of cases with mixed bacterial and fungal keratitis, presented between January 2000 and December 2007 at a tertiary referral hospital. The study was performed to identify and analyze its risk factors, causative microbial organisms, clinical features, and therapeutic outcomes.

RESULTS

Thirty-three cases of mixed bacterial and fungal keratitis in 33 patients were identified. Twenty-one cases (64%) were men, and the mean age was 64.3 ± 10.3 years. The average follow-up time was 7.2 ± 6.6 months. The most common predisposing factor for mixed keratitis was a history of ocular trauma (46%), followed by ocular surface diseases (27%). The mean pretreatment infiltration size was 11.7 ± 12.7 mm. The most common causative organisms were Staphylococcus epidermidis and Fusarium species. Seventeen cases (52%) underwent various surgical interventions: evisceration in 7 eyes (21%), penetrating keratoplasty in 5 eyes (15%), amniotic membrane transplantation in 5 eyes (15%), and so on. Seventeen cases (52%) were included in the initial treatment failure group. The significant risk factor for initial treatment failure was a large ulcer size (size over 15 mm) (P = 0.031).

CONCLUSIONS

The most common risk factor for mixed bacterial and fungal keratitis was ocular trauma, and the most common combination was Staphylococcus epidermidis and Fusarium species. Usually, patients with mixed bacterial and fungal keratitis have poor prognosis. Thus, when the infectious keratitis is running an atypical course or found unresponsive to the initial medical treatment, the possibility of a mixed infection by bacterial and fungal organisms should be considered.

Genetic characterization indicates that a specific subpopulation of Pseudomonas aeruginosa is associated with keratitis infections

Pseudomonas aeruginosa is a common opportunistic bacterial pathogen that causes a variety of infections in humans. Populations of P. aeruginosa are dominated by common clones that can be isolated from diverse clinical and environmental sources. To determine whether specific clones are associated with corneal infection, we used a portable genotyping microarray system to analyze a set of 63 P. aeruginosa isolates from patients with corneal ulcers (keratitis). We then used population analysis to compare the keratitis isolates to a wider collection of P. aeruginosa from various nonocular sources. We identified various markers in a subpopulation of P. aeruginosa associated with keratitis that were in strong disequilibrium with the wider P. aeruginosa population, including oriC, exoU, katN, unmodified flagellin, and the carriage of common genomic islands. The genome sequencing of a keratitis isolate (39016; representing the dominant serotype O11), which was associated with a prolonged clinical healing time, revealed several genomic islands and prophages within the accessory genome. The PCR amplification screening of all 63 keratitis isolates, however, provided little evidence for the shared carriage of specific prophages or genomic islands between serotypes. P. aeruginosa twitching motility, due to type IV pili, is implicated in corneal virulence. We demonstrated that 46% of the O11 keratitis isolates, including 39016, carry a distinctive pilA, encoding the pilin of type IV pili. Thus, the keratitis isolates were associated with specific characteristics, indicating that a subpopulation of P. aeruginosa is adapted to cause corneal infection.

Prospective comparison of microbial culture and polymerase chain reaction in the diagnosis of corneal ulcer

PURPOSE

To compare polymerase chain reaction (PCR) to microbial culture for the detection and identification of bacterial and fungal pathogens in microbial keratitis.

DESIGN

Prospective cohort study.

METHODS

A total of 108 consecutive corneal ulcers were cultured and analyzed by PCR using pan-bacterial and pan-fungal primers. PCR products were cloned, sequenced, and compared to culture results using standard bioinformatics tools.

RESULTS

Of the 108 samples, 56 were culture-positive, 25 for bacteria and 31 for fungi; 52 were culture-negative. After eliminating false-positive PCR products, 94 of 108 were positive by PCR, 37 for bacteria and 57 for fungi. Nineteen of 25 bacterial culture-positive samples were positive by PCR, and 29 of 31 samples culture-positive for fungi were positive by PCR. The majority of sequenced PCR products matched the positive culture results. Of the 52 culture-negative samples, 46 (88%) yielded pathogen deoxyribonucleic acid (DNA) PCR products, 18 bacterial and 28 fungal. These represented a variety of species, including at least three novel previously uncultured microbes.

CONCLUSIONS

PCR detects microbial DNA in the majority of bacterial and fungal corneal ulcers, and identifies potentially pathogenic organisms in a high proportion of culture-negative cases. Yield and concordance with culture are higher for fungal than bacterial ulcers. Practical use of the technique is limited by artefactual amplification of nonpathogenic organisms. PCR may be used as an adjunct to culture to identify potential pathogens in microbial keratitis.

Assessment of the use of anterior segment optical coherence tomography in microbial keratitis

PURPOSE

To investigate the imaging capabilities of anterior segment optical coherence tomography (AS OCT) in microbial keratitis and to assess whether measurements of the quantitative parameters, infiltrate thickness and corneal thickness, were possible.

DESIGN

Prospective, noncomparative, observational case series.

METHODS

The study was conducted at a university hospital clinical setting. Seven patients (eyes) with suspected microbial keratitis underwent standard clinical examination and treatment based on slit-lamp clinical findings. AS OCT scanning was performed on presentation and at two follow-up appointments. All scans were carried out with the scanning beam passing through the center of the infiltration and at a specific meridian. Examination was carried out by the same operator.

RESULTS

Corneal infiltration was imaged as a hyperreflective area in the corneal stroma on high-resolution AS OCT scans. Retrocorneal pathologic features and anterior chamber inflammatory cells could be imaged. Corneal and infiltrate thickness could be measured with calipers in six cases. In one case, corneal and infiltrate thickness could not be measured because of a thick inflammatory plaque attached to the endothelium. In this case, the width of the plaque was measured on serial scans.

CONCLUSIONS

AS OCT imaging provides a range of parameters that can be used to assess microbial keratitis and the treatment response objectively.

Topical corticosteroids as adjunctive therapy for bacterial keratitis

BACKGROUND

Bacterial keratitis is a serious ocular infectious disease that can lead to severe visual disability. Risk factors for bacterial corneal infection include contact lens wear, ocular surface disease, corneal trauma and previous ocular or eyelid surgery. Topical antibiotics constitute the mainstay of treatment in cases of bacterial keratitis where as the use of topical corticosteroids remains controversial. Topical corticosteroids are usually used to control inflammation using the smallest amount of the drug. Their use requires optimal timing, concomitant antibiotics and careful follow up.

OBJECTIVES

The objective of the review was to assess the clinical effectiveness and adverse effects of corticosteroids as adjunctive therapy for bacterial keratitis.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, and LILACS up to 15 January 2007. We also searched the Science Citation Index to identify additional studies that had cited the included trial, an online database of ongoing trials (www.clinicaltrials.gov), reference lists of included trials, earlier reviews and the American Academy of Ophthalmology guidelines. We also contacted experts to identify any unpublished and ongoing randomized trials.

SELECTION CRITERIA

We included randomized controlled trials evaluating adjunctive therapy with topical corticosteroids in people with bacterial keratitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all the retrieved articles. Methodological quality of the one included trial was assessed using forms developed using pre-specified criteria by at least two review authors. We planned to extract data on outcomes using forms developed for the purpose. We planned to report risk ratios for dichotomous outcomes and mean differences for continuous outcomes.

MAIN RESULTS

A single trial was eligible for inclusion in the review. Participants in the trial were randomized using a random numbers table. Allocation concealment was not attempted. Masking of participants, and care-providers was also not attempted. Outcome assessment was conducted independently by two physicians. Neither was masked to the treatment allocation. The trial reported the healing rate of epithelial defects and improvement in visual acuity.

AUTHORS' CONCLUSIONS

There are no good quality randomized trials evaluating the effects of adjunct use of topical corticosteroids in bacterial keratitis. The only randomized trial we identified in the literature suffered from major methodological inadequacies.

Clinical outcomes of keratitis

OBJECTION

To analyse the patient, clinical and microbiological variables associated with poor outcomes from keratitis in patients presenting to a major public hospital in Australia.

METHODS

A retrospective audit of the records of all patients who had a corneal scraping in 5 years at Princess Alexandra Hospital (Brisbane, Australia) was carried out. The outcome of a patient's episode of keratitis was classified as poor if they had final visual acuity of 6/60 or worse; had vision loss during treatment; or a complication of keratitis; or needed surgical intervention.

RESULTS

A final outcome was established in 207 cases during the 5-year period. Final vision of 6/12 or better was found in 48% (100) of cases while a poor outcome was seen in 28% (58). Linear regression showed poor outcomes were directly associated with age (P < 0.001) and disease severity (P < 0.001). Univariate analysis indicated that poor outcomes were more likely in patients who had had prior ocular surgery (P = 0.005) or ocular surface disease (P = 0.01) and were also associated with presenting visual acuity of worse than 6/60 (P < 0.001) and isolation of Streptococcus pneumoniae (P = 0.002). While patients with traumatic keratitis, contact lens-related keratitis or negative corneal cultures (P = 0.009) were more likely to have good outcomes. Multivariate analysis showed that the relative risk of a patient having a poor outcome was 4.3x (CI 2.0-9.5) if they had severe keratitis, 4.1x (CI 1.8-9.5) if they had keratitis related to ocular surface disease and 3.8x (CI 1.8-8.3) if they were over 50 years old.

CONCLUSIONS

An outcome of poor vision, vision loss during treatment, surgical intervention or complication of keratitis is more likely in patients with severe keratitis, keratitis related to prior ocular surface disease or older age.

Initial therapy for suppurative microbial keratitis in Iraq

OBJECTIVE

To provide data-based guidelines for selection of an appropriate initial therapy for management suppurative microbial keratitis (SMK) in Iraq.

METHODS

This case-series study enrolled patients with clinical signs of suppurative keratitis suspected of being microbial, presented prospectively at Ibn Al-Haetham Teaching Eye Hospital from April 2002 to March 2005. Predisposing factors, microbial profile and sensitivities of isolated bacteria were determined. If direct microscopic examination of smears was negative for fungal elements, initial therapy started with ciprofloxacin 0.3% eye-drops. Subsequent treatment depends on clinical response and cultures' results.

RESULTS

Out of 396 cases enrolled, positive cultures were obtained in 232 cases (58.6%). The predominating agents isolated were Gram-positive cocci (Staphylococcus and Streptococcus) 75 cases (18.9%); Pseudomonas 68 cases (17.2%); and fungal species 74 cases (18.7%). Treatment was initiated with ciprofloxacin eye-drops in 364 cases, a favourable response was recorded in 185 cases (50.8%), addition of other antimicrobial drugs was required in 56 cases (15.4%), while failure of treatment was recorded in 123 cases (33.8%).

CONCLUSION

Use of ciprofloxacin eye drops alone as an initial therapy cannot cover most of the causative agents of SMK in Iraq. Addition of another drug can provide a better coverage for the predominating causative agents. The choice of this additional drug is based on the suspected infecting agent depending on the regional predisposing factors, and the clinical features.

Les abcès graves de la cornée : à propos de 100 cas

PURPOSE

To study predisposing factors, clinical aspects, and microbiological diagnosis in severe microbial keratitis, and to discuss the therapy and visual outcome.

MATERIAL

and methods: A prospective and retrospective study concerning patients presenting microbial keratitis hospitalized in department B of the Hedi Raies Ophthalmology Institute (Tunis, Tunisia), from August 1996 to November 2004.

RESULTS

One hundred patients with microbial keratitis were hospitalized (45 females and 55 males; ranging in age from 11 to 87 years). The principal predisposing factors were ocular surface pathology (30%), ocular trauma (28%), prior ocular surgery (17%), and contact lens wear (8%). The corneal scraping culture was positive in 42% of cases, isolating Gram-positive bacteria (48.6%), Gram-negative bacteria (29.7%), and fungi (21.6%). The majority of our patients (93%) had broad-spectrum topical antibiotics with therapeutic success in 53.8% of cases. Systemic antifungal agents were indicated in 17 cases. Surgery was necessary in 25.8% of cases: therapeutic keratoplasty in five cases and deleted keratoplasty in nine cases. Final visual acuity was equal to or better than at admission in 81% of cases. Anatomic loss of the eye was observed in eight cases (evisceration, six cases; enucleation, two cases).

CONCLUSION

microbial keratitis is a frequent and severe pathology that can lead to blindness. Only early and adapted management can improve the prognosis of severe microbial keratitis.

Infective keratitis in older patients: a 4 year review, 1998-2002

BACKGROUND/AIM

There are few clinical series in the literature of infective keratitis in the elderly, even though this age group constitutes a significant proportion of those affected by this condition. The authors aimed to determine the incidence and risk factors for infective keratitis in those over 60 years, the causative organisms, antibiotic susceptibilities, visual and tectonic outcome, and surgical intervention rate.

METHODS

A retrospective review of all patients aged 60 years and over admitted to the Sydney Eye Hospital with a diagnosis of infective keratitis, between September 1998 and December 2002.

RESULTS

190 patients were identified with a mean age of 75.5 (SD 9.6) years (range 60-101). Local risk factors were found in 93.7%, and systemic risk factors in 27.9%. Organisms were cultured in 62.8%, and 7.9% had positive herpes simplex virus (HSV) polymerase chain reaction (PCR). Perforation or severe thinning occurred in 36% overall, but in 80% with positive HSV PCR. Acute surgical intervention was required in 43.7%, with acute penetrating keratoplasty performed in 17.9%, and 8.9% required evisceration. Mean presenting visual acuity was 1.82 (SD 1.24), equivalent to 6/300, excluding 26.3% with vision of light perception (LP) or worse. Mean final visual acuity was 1.24 (SD 1.16), equivalent to 6/100, excluding 19.5% with vision of LP or worse (p<0.0005).

CONCLUSIONS

The elderly represent a distinct clinical group in the context of microbial keratitis. Predisposing factors are very common, they present with poor vision, have a high complication and surgical intervention rate, and a poor visual outcome compared to younger patients. The microbiological spectrum is similar to younger age groups, except that HSV is more common and may increase the risk of severe corneal thinning and perforation. Most bacterial isolates remain sensitive to currently available antibiotic preparations.

Clinical and epidemiological advantages of culturing bacterial keratitis

PURPOSE

To examine how the corneal culture result is associated with the antibacterial treatment response rate of ulcerative keratitis in a prospective cohort study and to determine whether culture confirmation affects the relative treatment effect in randomized clinical trials of bacterial keratitis.

METHODS

The influence of a positive bacterial culture on the rates of antibacterial improvement and cure was estimated by proportional hazards regression among 608 patients with ulcerative keratitis treated with topical ciprofloxacin monotherapy. The interaction of culture confirmation on the relative cure rates of 735 patients enrolled in 4 clinical trials comparing fluoroquinolone monotherapy to combined cephalosporin and aminoglycoside therapy was evaluated by metaregression.

RESULTS

In a prospective cohort study, bacterial keratitis that was culture positive and longer than 4 mm had a 37% (95% confidence interval, 20%, 51%) slower improvement rate and a 56% (95% confidence interval, 41%, 67%) slower cure rate during ciprofloxacin therapy. Among randomized clinical trials, the culture result did not modify the relative effect of treatments having similar 1-week cure rates.

CONCLUSIONS

Culture confirmation affects the antibacterial therapeutic response rate of ulcerative keratitis and, while not modifying the comparative effect of equivalent antibacterial treatments, facilitates generalizability of clinical trials of bacterial keratitis.

The efficacy and safety of topical polymyxin B, neomycin and gramicidin for treatment of presumed bacterial corneal ulceration

AIM

To evaluate the clinical efficacy and safety of topical polymyxin B, neomycin, and gramicidin for the treatment of suspected bacterial corneal ulceration at the Leiden University Medical Center.

METHODS

Patients with a diagnosis of a suspected bacterial corneal ulcer between April 1995 and February 2002 were retrospectively identified and reviewed; clinical and microbiological features and response to therapy were analysed. All patients were treated with Polyspectran eye drops.

RESULTS

In total, 91 patients were included in this analysis. Bacteriological cultures of 46 patients (51%) were positive and revealed 51 microorganisms. Staphylococcus aureus (29.4%) and Pseudomonas aeruginosa (23.5%) were the most frequently encountered bacteria. Eighteen patients switched therapy before complete healing of the corneal ulceration, four patients were lost to follow up. Of the 69 patients who completed Polyspectran treatment, re-epithelialisation occurred in 68 patients (99%) and on average took 12.6 (median 8) days. Among 91 patients, there were four perforations and one evisceration. Seven toxic or allergic reactions were reported.

CONCLUSION

This study shows that the combination of polymyxin B, neomycin, and gramicidin is an effective and safe treatment of suspected corneal ulceration.

In vivo effects of fluoroquinolones on rabbit corneas

PURPOSE

The use of topical fluoroquinolones to treat microbial keratitis is associated with an increased incidence of corneal perforation compared to other standard treatments. This study examined the effects of topical fluoro-quinolones on corneal collagen and keratocytes in intact rabbit corneas and corneas with an epithelial defect.

METHODS

Studies consisted of one group of intact corneas and one group of corneas where a 6-mm epithelial defect was created with a surgical scrape. Within each group, eyes were randomly assigned to one of four topical medications (0.3% ciprofloxacin, 0.3% ofloxacin, fortified antibiotics (1.36% tobramycin, 5% cefrazolin) or Tears Naturale (Alcon Laboratories, Frenchs Forest, NSW, Australia). Two drops were instilled hourly for 48 h and then 2-hourly for an additional 48 h. At 96 h the corneas were removed and processed for light microscopy, immunohistology for collagen IV, V and VI, and apoptosis staining.

RESULTS

In intact rabbit corneas there was no demonstrable difference between treatment groups. In corneas with an epithelial defect, both fluoroquinolones delayed epithelial healing when compared to fortified antibiotics or tears. Keratocyte loss was seen in all groups and was greatest in the ofloxacin group. Median stromal thickness with keratocyte loss were: ofloxacin 30%; ciprofloxacin 10%; fortified antibiotics 7.5%; and tears 15% (ofloxacin vs tears, Mann-Whitney = 16.0, P = 0.09). Keratocyte loss did not correlate with the amount of demonstrable apoptosis. Collagens IV, V and VI showed no differences between treatments.

CONCLUSIONS

These results suggest that ofloxacin is potentially cytotoxic to corneal keratocytes. Such an effect could lead to the observed increased incidence of corneal perforation in microbial keratitis.

Corneal ciprofloxacin precipitation during bacterial keratitis

PURPOSE

To examine how age affects the risk of developing a white corneal precipitate during ciprofloxacin therapy for bacterial keratitis and to explore the effect of a white precipitate on rates of clinical improvement and cure.

DESIGN

Prospective, multicenter, observational cohort study.

METHODS

Occurrence of a white precipitate of the corneal surface was recorded among 624 patients with presumed bacterial keratitis who were treated with topical ciprofloxacin 0.3% solution or ointment. Relative risks of corneal precipitation were estimated from logistic regression for age categories and other clinical characteristics. The time-dependent effects of precipitate on rates of infection resolution and corneal reepithelialization were estimated by proportional hazards regression.

RESULTS

Ninety-five (15.2%) patients developed a white corneal precipitate during ciprofloxacin therapy; 72 (75.8%) began within the first 3 days of treatment. Compared with those younger than 40 years old, patients aged 60 to 69 years had 2.8 (95% confidence limits [CL], 1.9, 3.9) times the risk of ciprofloxacin precipitation; patients 70 years and older had 3.7 (95% CL, 2.6, 5.0) times the risk. Median duration of the visible corneal precipitate was 8.5 days (90% decile, 32 days). Presence of ciprofloxacin precipitation did not significantly affect the time until therapeutic improvement (P =.09) but slowed the time until reepithelialization by 55% (95% CL 32%, 70%).

CONCLUSIONS

Older patients treated with topical ciprofloxacin for bacterial keratitis have a higher risk of corneal deposition. A white precipitate apparently does not interfere with antibacterial therapeutic response but may delay epithelial healing of ulcerative keratitis.

Effect of topical fluoroquinolones on the expression of matrix metalloproteinases in the cornea

BACKGROUND

Matrix metalloproteinases play an important role in extracellular matrix deposition and degradation. Based on previous clinical observations of corneal perforations during topical fluoroquinolone treatment, we decided to evaluate the comparative effects of various fluoroquinolone eye drops on the expression of matrix metalloproteinases (MMPs) in cornea.

METHODS

Eighty female Lewis rats were divided into two experimental groups: intact and wounded corneal epithelium. Uniform corneal epithelial defects were created in the right eye with application of 75% alcohol in the center of the tissue for 6 seconds. The treatment groups were tested as follows: 1) Tear drops: carboxymethylcellulose sodium 0.5 % (Refresh, Allergan); 2) Ciprofloxacin 0.3% (Ciloxan, Alcon); 3) Ofloxacin 0.3%(Ocuflox, Allergan); 4) Levofloxacin 0.5%(Quixin, Santen). Eye drops were administered 6 times a day for 48 hours. Rats were sacrificed at 48 hours. Immunohistochemical analysis and zymography were conducted using antibodies specific to MMPs-1, 2, 8 and 9.

RESULTS

MMP-1, MMP-2, MMP-8 and MMP-9 expression were detected at 48 hrs in undebrided corneal epithelium groups treated with the topical fluoroquinolones. No statistical difference was observed in quantitative expression of MMPs among ciprofloxacin 0.3%, ofloxacin 0.3%, levofloxacin 0.5%. When the artificial tear group and the fluoroquinolone groups with corneal epithelial defect were compared, increased expression of MMPs was observed as a result of the wound healing process. However, the fluoroquinolone treated group exhibited high statistically significantly levels of MMPs expression.

CONCLUSIONS

Our study provides preliminary evidence that topical application of fluoroquinolone drugs can induce the expression of MMP-1, MMP-2, MMP-8 and MMP-9 in the undebrided corneal epithelium compared to artificial tear eye drops.

Severe infective keratitis leading to hospital admission in New Zealand

AIM

To identify key risk factors and the management and outcome of severe infective keratitis leading to public hospital admission in New Zealand.

METHODS

Over a 2 year period, all admissions of presumed infective keratitis to Auckland Hospital were identified. The clinical records of all 103 cases were retrospectively reviewed with respect to clinical features, risk factors, management, and outcomes.

RESULTS

The mean time from first symptoms or signs and presentation to hospital was 8.9 (SD 15.5) days. The majority of subjects, 88%, had at least one of the risk factors commonly associated with infective keratitis including previous ocular surgery (30%), contact lens wear (26%), topical corticosteroid use (25%), and ocular trauma (24%). Corneal scraping was performed in 92% and of a total of 105 scrapes, 71% were positive. Bacteria were isolated in all these cases, the majority being Gram positive organisms (72%). The most common isolates identified were coagulase negative Staphylococcus (16%), Propionibacterium acnes (14%), Staphylococcus epidermidis (11%), and Streptococcus pneumoniae (9%). In addition, yeasts were isolated in 5%, fungi in 4%, virus in 2%, and chlamydia in 1%. Importantly, polymicrobial infection accounted for 33% of culture positive cases. Antimicrobial treatment was changed on the basis of culture results in 17 cases (16.5%). Median initial visual and final best corrected visual acuity was 6/36-6/48 (logMAR 0.86) (IQR 0.39-2.00) and 6/12-6/15 (logMAR 0.360) (IQR 0.15-1.70), respectively. Previous ocular surgery and topical corticosteroid use were significantly associated with poorer visual acuity. The mean hospital stay was 5.8 days and the median 4.0 (IQR 2.0-8.0) days. Longer duration of stay was associated with the presence of hypopyon, larger ulcers, previous ocular surgery, and poor visual acuity.

CONCLUSIONS

Infectious keratitis is an important cause of ocular morbidity. A significant proportion of cases have potentially modifiable risk factors. Previous ocular surgery and topical corticosteroid use, in particular, were associated with poorer visual outcomes. Many cases of severe keratitis might be avoided, or their severity reduced, by appropriate education of patients and ophthalmologists.

Simplifying collection of corneal specimens in cases of suspected bacterial keratitis

Identification of the causative organisms in suspected bacterial keratitis traditionally involves collecting multiple corneal scrapes, which are plated directly onto different solid agar culture media. Difficulties have been reported with this practice, so the development of a simpler diagnostic method in suspected bacterial keratitis would be useful. It is unclear whether a single corneal scrape sent to the microbiology laboratory in a liquid transport culture medium (indirect method) is as reliable for the diagnosis of bacterial keratitis as inoculation of multiple scrapes directly onto agar plates (direct method). To investigate this, bacterial recovery was assessed following transfer and transport of different concentrations and types of bacteria from an artificially contaminated surgical blade into brain heart infusion (BHI). Bacterial recovery rates between the proposed (indirect) and standard (direct) method were then compared after the in vitro inoculation of pig corneas and following specimen collection in patients with presumed bacterial ulcerative keratitis. Recovery of bacteria from contaminated surgical blades was found to be the same from both solid and liquid culture media. There was no significant difference in the numbers of positive cultures from solid (direct) and liquid (indirect) culture media, both in the experimental pig cornea inoculation study (P = 0.34) and in experiments with patients with clinical infections (P = 0.4), with an 85.2% agreement between methods (kappa = 0.61, P < 0.0001). In conclusion, therefore, the collection of two corneal scrapes, one used for Gram staining and the other transported in BHI followed by plating and subculturing in an enrichment medium, provides a simple method for the investigation of presumed bacterial keratitis.

Bacterial keratitis: predisposing factors, clinical and microbiological review of 300 cases

AIM

To identify predisposing factors and to define clinical and microbiological characteristics of bacterial keratitis in current practice.

METHODS

A retrospective analysis of the hospital records of patients presenting with bacterial keratitis and treated at the Quinze-Vingts National Center of Ophthalmology, Paris, France, was performed during a 20 month period. A bacterial keratitis was defined as a suppurative corneal infiltrate and overlying epithelial defect associated with presence of bacteria on corneal scraping and/or that was cured with antibiotic therapy. Risk factors, clinical and microbiological data were collected.

RESULTS

300 cases (291 patients) of presumed bacterial keratitis were included. Potential predisposing factors, usually multiple, were identified in 90.6% of cases. Contact lens wear was the main risk factor (50.3%). Trauma or a history of keratopathy was found in 15% and 21% of cases, respectively. An organism was identified in 201 eyes (68%). 83% of the infections involved Gram positive bacteria, 17% involved Gram negative bacteria, and 2% were polymicrobial. Gram negative bacteria were associated with severe anterior chamber inflammation (p=0.004), as well as greater surface of infiltrates (p=0.01). 99% of ulcers resolved with treatment, but only 60% of patients had visual acuity better than the level at admission, and 5% had very poor visual outcome.

CONCLUSIONS

Contact lens wear is the most important risk factor. Most community acquired bacterial ulcers resolve with appropriate treatment.

Does identification of the causal organism of corneal ulcers influence the outcome?

PURPOSE

To investigate whether identification of the causal organism in corneal ulcers influences their outcome.

METHODS

We retrospectively studied 114 patients, 72 males and 42 females aged 6-89 years, admitted to this eye clinic during the years 1994-2000 on account of an infectious corneal ulcer. Their examination included a detailed history, visual acuity measurement, and biomicroscopy in everyday follow-up. The ulcers were classified according to their severity and outcome. We assessed the cases where cultures had been done, reviewed the results, and searched for a possible correlation between the outcome and the fact of culturing the ulcer and identifying the causal organism.

RESULTS

Of the 114 corneal ulcers studied, 23 were mild, 49 moderate, and 42 severe. Fifty (44%) had not been cultured, but 64 ulcers (56%) had been cultured, with a positive result in 37 cases (58%), Staphylococcus and Pseudomonas species being the most common organisms found. In moderate and severe ulcers, there was a tendency to a higher proportion of successful outcome for cultured ulcers, but with no significant correlation.

CONCLUSIONS

Despite a tendency towards favorable results in culture-positive corneal ulcers, the influence of the detection of the organism on their outcome has not been proved. The role of the initial broad-spectrum antibiotic therapy remains important.

Indecision about corticosteroids for bacterial keratitis: an evidence-based update

PURPOSE

To quantify the effect of topical corticosteroids on bacterial keratitis.

CLINICAL RELEVANCE

Bacterial keratitis is an economically important infection affecting 1 in 10,000 Americans annually. The predisposing factors, prior ocular health, infecting microorganisms, inflammatory severity, and therapeutic choices can affect the course and outcome. Antibacterial treatment is often curative but does not guarantee good vision. Because many treated patients develop a sight-limiting corneal problem, antiinflammatory therapy has sometimes been recommended.

LITERATURE REVIEWED

Publications from 1950 to 2000 that evaluated the effect of corticosteroids on bacterial keratitis in animal experiments, case reports and series, case-comparison and cohort studies, and clinical trials were systematically identified by electronic and manual search strategies.

RESULTS

The use of a topical corticosteroid before the diagnosis of bacterial keratitis significantly predisposed to ulcerative keratitis in eyes with preexisting corneal disease (odds ratio [OR], 2.63; 95% confidence limits [CL], 1.41, 4.91). Once microbial keratitis occurred, prior corticosteroid use significantly increased the odds of antibiotic treatment failure or other infectious complications (OR, 3.75; 95% CL, 2.52, 5.58). However, the effect of a topical corticosteroid with antibiotics after the onset of bacterial keratitis was unclear. Experimental models suggested likely advantages, but clinical studies did not show a significant effect of topical corticosteroid therapy on the outcome of bacterial keratitis (OR, 0.62; 95% CL, 0.25, 1.54).

CONCLUSIONS

Topical corticosteroids increase the risk of infectious complications affecting the cornea but may or may not have an effect during antibacterial therapy. The unproven role of corticosteroids in the adjunctive treatment of bacterial keratitis highlights the need to collect prospective information that would guide appropriate management for this common eye disease.