Microbial keratitis: what's the preferred initial therapy?

3D-Printed Inherently Antibacterial Contact Lens-Like Patches Carrying Antimicrobial Peptide Payload for Treating Bacterial Keratitis

Delivery of therapeutic agents through contact lenses-like patches is a promising strategy to achieve significant bioavailability with negligible eye drainage. The present study investigates the preparation and 3D printing of mucoadhesive gelatin methacryloyl (GelMA)/chitosan methacryloyl (ChiMA) hydrogels to fabricate them as contact lens-like patches (CLP) loaded with antimicrobial peptide, S100A12 (AMP) for treating bacterial keratitis (BK). Extrusion technology is used to print the patches layer by layer to form a hemispherical scaffold suitable for eyewear, and 3D-printed CLP is crosslinked using Irgacure 2959 under UV light. The results from the in vivo experiment conducted on Pseudomonas aeruginosa-infected BK rabbit model after the treatment with AMP-loaded CLP have shown a significant decrease in bacterial load when plated for CFU. The newly developed delivery system containing AMP has great potential to overcome the treatment challenges of multidrug resistance (MDR) in bacteria and eliminate the frequent dosing associated with eye drops. The presence of chitosan in the formulation provides a synergetic effect on the AMP in disrupting bacterial biofilms. The ease of using 3D printing will open new avenues for optimizing the dosage depending on the severity of the BK in the patients, which can be used as personalized medicine.

Clinical factors associated with positive corneal culture in suspected microbial keratitis

AIMS

Determine demographic and clinical characteristics associated with positive culture in suspected microbial keratitis.

METHODS

Retrospective audit of patients that had corneal scrapings between October 1999-September 2004 at Princess Alexandra Hospital. Clinical information was gathered from medical records, smear and culture results from the local microbiology database. Univariate and multivariate analyses of variables associated with positive cultures and calculation of population attributable risk percentage (PAR).

RESULTS

Univariate analysis showed that positive cultures were associated with patients over 60 years (81% vs 55%; p < 0.001), presenting visual acuity (VA) of 6/24 or worse (74% vs 57%; p = 0.012) or contact lens-related keratitis (CLK 77% vs 62%; p = 0.08). Analysis of patients' clinical presentation showed that positive culture was associated with a central epithelial defect (74% vs 57%; p = 0.012), anterior chamber reaction of 2 + cells or worse (73% vs 56%; p = 0.03), an epithelial defect of 2 mm or more in diameter (71% vs 50%; p = 0.006) or no prior treatment with antibiotics (68% vs 56%; p = 0.053). Multivariate analysis showed the independent variables associated with positive cultures were VA of 6/24 or worse on presentation, contact lens-related keratitis, age greater than 60 years, an anterior chamber reaction of 2 + cells or worse and no prior treatment with antibiotics. The factor with the highest attributable risk (PAR%) for a positive corneal scraping was VA of 6/24 or worse on presentation (21%).

CONCLUSIONS

In this series positive cultures were associated with poor presenting VA contact lens keratitis (CLK), older age, anterior chamber reaction and no prior treatment with antibiotics.

Development and Validation of a Natural Language Processing Algorithm to Extract Descriptors of Microbial Keratitis From the Electronic Health Record

PURPOSE

The purpose of this article was to develop and validate a natural language processing (NLP) algorithm to extract qualitative descriptors of microbial keratitis (MK) from electronic health records.

METHODS

In this retrospective cohort study, patients with MK diagnoses from 2 academic centers were identified using electronic health records. An NLP algorithm was created to extract MK centrality, depth, and thinning. A random sample of patient with MK encounters were used to train the algorithm (400 encounters of 100 patients) and compared with expert chart review. The algorithm was evaluated in internal (n = 100) and external validation data sets (n = 59) in comparison with masked chart review. Outcomes were sensitivity and specificity of the NLP algorithm to extract qualitative MK features as compared with masked chart review performed by an ophthalmologist.

RESULTS

Across data sets, gold-standard chart review found centrality was documented in 64.0% to 79.3% of charts, depth in 15.0% to 20.3%, and thinning in 25.4% to 31.3%. Compared with chart review, the NLP algorithm had a sensitivity of 80.3%, 50.0%, and 66.7% for identifying central MK, 85.4%, 66.7%, and 100% for deep MK, and 100.0%, 95.2%, and 100% for thin MK, in the training, internal, and external validation samples, respectively. Specificity was 41.1%, 38.6%, and 46.2% for centrality, 100%, 83.3%, and 71.4% for depth, and 93.3%, 100%, and was not applicable (n = 0) to the external data for thinning, in the samples, respectively.

CONCLUSIONS

MK features are not documented consistently showing a lack of standardization in recording MK examination elements. NLP shows promise but will be limited if the available clinical data are missing from the chart.

Epidemiology, clinical profile and treatment outcomes of bacterial and fungal keratitis

PURPOSE

The purpose of the study is to determine the microbiological etiology, epidemiological factors, and clinical profile and treatment outcomes of infective keratitis in Ophthalmology department, Minia University, Egypt.

METHODS

Prospective, nonrandomized, observational clinical series of cases, including 150 patients with mean age 30 (range 12 to 85 years), 90 patients (60%) were males and 60 (40%) were females, clinically diagnosed as infective corneal ulcer, attending the Ophthalmology Department-Faculty of Medicine. Minia University, Minia, Egypt. From December 2018 to December 2020. Detailed history taking and all clinical findings were collected. Corneal scrapings were obtained from patients and subjected to staining and culture for bacterial and fungal pathogens; Bacterial and fungal growth were identified by standard laboratory procedures.

RESULTS

Corneal trauma by a vegetative matter was the commonest risk factor associated with infective keratitis in 92 cases (61.3%). Smear and culture was positive in 83 cases (58.4%) of 142 corneal scrapings obtained, of which 60 cases were fungal (72.3%), 21 cases were bacterial (25.3%) and two cases were mixed bacterial and fungal (2.4%), Aspergillus species was the commonest fungal species isolated in fungal keratitis. One hundred forty-two cases (94.67%) healed completely with scar. Only six cases (4%) required evisceration due to aggressive presentation from the start and keratoplasty was performed for two cases (1.33%).

CONCLUSIONS

Fungal keratitis was the commonest type in cases attending to our department. Adequate diagnosis, management and follow-up helped in achieving high successful curative outcomes.

CLINICAL TRIAL NUMBER

Clinical Trials.gov ID: NCT04894630. Time of registration 1 December 2018.

Melting corneal ulcers (keratomalacia) in dogs: A 5-year clinical and microbiological study (2014-2018)

OBJECTIVES

To identify bacterial microorganisms associated with canine keratomalacia, review their antimicrobial sensitivity, and evaluate clinical outcomes compared to results of microbial culture.

METHODS

Retrospective analysis of clinical records of dogs diagnosed with a melting corneal ulcer presented to a referral hospital in Hertfordshire, UK between 2014 and 2018.

RESULTS

One hundred and ten melting corneal ulcers were sampled in 106 dogs. The most common pure bacterial isolate was Pseudomonas aeruginosa (n = 26) followed by β-hemolytic Streptococcus (n = 12). Melting corneal ulcers that cultured coagulase-positive Staphylococcus, coliform bacteria, Pasteurella multocida, Enterococcus, and Streptococcus viridans presented in smaller numbers and were analyzed together (n = 16). Multiple cultures were identified in nine cases (n = 9). Forty-seven cultures yielded no bacterial growth (n = 47). The susceptibility to fluoroquinolones remained high with the exception of β-hemolytic Streptococci. There was no significant difference in the ulcer severity at presentation in regard to the cultured bacteria. Overall, 63 eyes (57%) received surgical grafting in addition to medical treatment. In 14 cases (13%), the progression of corneal melting despite medical ± surgical treatment resulted in enucleation. Fifty-seven percent (8/14) of the enucleated eyes cultured pure Pseudomonas aeruginosa isolates. In contrast, all β-hemolytic Streptococcus-associated ulcers healed.

CONCLUSIONS

The most common bacterial species associated with canine keratomalacia were Pseudomonas aeruginosa and β-hemolytic Streptococcus. Because of the variation in antibacterial sensitivity between these two species, bacterial culture and sensitivity testing should be performed in all dogs presenting with keratomalacia. Melting corneal ulcers associated with pure Pseudomonas infection were significantly more likely to result in globe loss than melting corneal ulcers associated with other cultures.

Microbial keratitis in a tertiary centre in Queensland, Australia (1999-2015)

Clinical relevance: Keratitis is common and studies of blindness throughout the world have found that corneal disease is the second most common cause of blindness.Background: Microbial keratitis a bacterial, fungal, or protozoan disease of the cornea, characterised by a corneal infiltrate with an overlying epithelial defect and associated anterior chamber reaction.Methods: Patients were identified through the hospital pathology database and a retrospective chart review of all patients with a positive corneal culture between 1999 and 2015 at Princess Alexandra Hospital was carried out.Results: There were 895 records from 779 patients included and additional 107 records excluded. The average age of the included patients was 58.9 years (SD 21.0). Males made up 498 (55.6%) of the included patients. Contact lens microbial keratitis (CLMK) was the most common risk factor for MK and was significantly more common in younger patients. CLMK was significantly associated with cultures positive for Pseudomonas aeruginosa (p < 0.001) while MK secondary to ocular surface disease and prior ocular surgery were more commonly associated with gram-positive organisms (p < 0.001). Monotherapy with a fluoroquinolone was the most common treatment for patients with MK. Good outcomes were seen in 57% of patients.Conclusion: In this patient group, contact lens wear was the most common risk factor for MK. Pseudomonas aeruginosa was the most common isolate.

Advancing the stimuli response of polymer-based drug delivery systems for ocular disease treatment

Recent exploitations of stimuli-responsive polymers as ophthalmic drug delivery systems for the treatment of eye diseases are summarized and discussed.

Spectrum and Sensitivity of Bacterial Keratitis Isolates in Auckland

Background. The bacteria isolated from severe cases of keratitis and their antibiotic sensitivity are recognised to vary geographically and over time. Objectives. To identify the most commonly isolated bacteria in keratitis cases admitted over a 24-month period to a public hospital in Auckland, New Zealand, and to investigate in vitro sensitivity to antibiotics. Methods. Hospital admissions for culture-proven bacterial keratitis between January 2013 and December 2014 were identified. Laboratory records of 89 culture positive cases were retrospectively reviewed and antibiotic sensitivity patterns compared with previous studies from other NZ centres. Results. From 126 positive cultures, 35 species were identified. Staphylococcus was identified to be the most common isolate (38.2%), followed by Pseudomonas (21.3%). Over the last decade, infection due to Pseudomonas species, in the same setting, has increased (p ≤ 0.05). Aminoglycosides, cefazolin, ceftazidime, erythromycin, tetracycline, and doxycycline were 100% effective against tested isolates in vitro. Amoxicillin (41.6%), cefuroxime (33.3%), and chloramphenicol (94.7%) showed reduced efficacy against Gram-negative bacteria, whereas penicillin (51%) and ciprofloxacin (98.8%) showed reduced efficacy against Gram-positive bacteria. Conclusions. Despite a shift in the spectrum of bacterial keratitis isolates, antibiotic sensitivity patterns have generally remained stable and show comparability to results within the last decade from NZ centres.

Lack of consensus on corneal abrasion management: results of a national survey

Objectives:

Our objective was to determine the practice patterns of Canadian emergency physicians with respect to the management of traumatic corneal abrasions.

Methods:

After developing our instrument and pilot testing it on a sample of emergency residents, we randomly surveyed 470 members of the Canadian Association of Emergency Physicians, using a modified Dillman technique. We distributed a pre-notification letter, an 18-item survey, and appropriate follow-up surveys to non-responders. Those members with an email address (n= 400) received a Web-based survey, and those without (n= 70) received a survey by post. The survey focused on the indications and utilization of analgesics (oral and topical), cycloplegics, eye patches and topical antibiotics.

Results:

Our response rate was 64% (301/470), and the median age of respondents was 38 years. Most (77.7%) were male, 71.8% were full-time emergency physicians, 76.5% were emergency medicine certified, and 64.4% practised in teaching hospitals. Pain management preferences (offered usually or always) included oral analgesics (82.1%), cycloplegics (65.1%) and topical nonsteroidal anti-inflammatory drugs (NSAIDs) (52.8%). Only 21.6% of respondents performed patching, and most (71.2%) prescribed topical antibiotics, particularly for contact lens wearers and patients with ocular foreign bodies. Two-thirds of the respondents provided tetanus toxoid if a foreign body was present, and 46.2% did so even if a foreign body was not present. Most respondents (88.0%) routinely arranged follow-up.

Conclusions:

This national survey of emergency physicians demonstrates a lack of consensus on the management of traumatic corneal abrasions. Further study is indicated to determine the optimal treatment, particularly regarding the use of topical NSAIDs.

Community opinions in the management of corneal ulcers and ophthalmic antibiotics: a survey of 4 states

OBJECTIVE

To evaluate the ophthalmic community's current opinions of the management of bacterial keratitis and usage of the currently available ophthalmic antibiotics.

METHODS

An anonymous questionnaire was mailed to ophthalmologists in California, Florida, Illinois, and Missouri. The results were tabulated and analyzed statistically.

RESULTS

Six hundred twenty-nine usable questionnaires (10.3%) were returned. In the management of corneal ulcers, 42.2% of comprehensive ophthalmologists and 75.3% of cornea specialists perform Gram stains some of the time. A total of 73.3% of comprehensive ophthalmologists and 93.7% of cornea specialists perform corneal cultures some of the time. A total of 88.8% of comprehensive ophthalmologists and 76% of cornea specialists initiate treatment with the newer fluoroquinolone antibiotics. A total of 12.1% of comprehensive ophthalmologists and 41% of cornea specialists would select fortified antibiotics for the treatment of corneal ulcers. The percentage of those who feel that fortified antibiotics are superior ranges from 17.7% for comprehensive ophthalmologists to 33.3% for cornea specialists. A total of 65.7% of comprehensive ophthalmologists indicate that the newer fluoroquinolones have impacted their practices, and 58.3% indicate that they represent an improvement over older fluoroquinolones.

CONCLUSIONS

Most responding ophthalmologists initiate empiric therapy with the newer fluoroquinolone antibiotics for corneal ulcers, forgoing Gram staining and culturing. However, respondents are not universally sanguine about the newer fluoroquinolones. The practice patterns and opinions on antibiotics differ almost universally between comprehensive ophthalmologists and cornea specialists. Larger, more detailed surveys and more specific analyses would help to further establish the factors that lead to differing management choices and opinions.

Mucoadhesive nanoparticles as carrier systems for prolonged ocular delivery of gatifloxacin/prednisolone bitherapy

A fluoroquinolone/glucocorticoid combination for the treatment of bacterial keratitis in the form of mucoadhesive nanoparticle suspensions was developed to prolong the release and improve patient compliance. Gatifloxacin/prednisolone loaded nanoparticles were prepared using Eudragit RS 100 and RL 100 and coated with the bioadhesive polymer, hyaluronic acid. FT-IR and DSC studies revealed no interaction between gatifloxacin and prednisolone. The effects of the drug:polymer ratio (D:P) and the RS/RL ratio were studied. The obtained nanoparticles were distinct and spherical with a solid dense structure. They have average particle size range of 315.2 to 973.65 nm. Increasing the D:P ratio significantly lowered the entrapment efficiency for both drugs (p < 0.05). The nanoparticle suspensions revealed significantly prolonged drug release comparing to the free drugs (p < 0.05) with no burst effect. Increasing the polymer concentration and the Eudragit RS ratio significantly decreased the release efficiency values. Gatifloxacin showed anomalous release (n = 0.4943) from 1:1 D:P ratio nanoparticle suspension and Fickian diffusion mechanism (n < 0.45) from formulas prepared at higher D:P ratios. Gatifloxacin showed better bioavailability and sustained action in aqueous humor and corneal tissue from the nanoparticles compared to the commercial eye drops. The resulting nanoparticle suspension is promising in reducing dose frequency and improving patient compliance.

The clinical diagnosis of microbial keratitis

PURPOSE

To evaluate the ability of ophthalmologists to predict the laboratory results of presumed microbial keratitis and to explore which findings may influence diagnostic prognostication.

DESIGN

Prospective, cross-sectional study.

METHODS

Fifteen ophthalmologists completed study forms at the initial presentation of patients with presumed microbial keratitis. After predicting the category of microbial recovery, clinicians submitted corneal scrapings for masked laboratory processing. The relative effects of ocular inflammatory signs on correct microbial diagnosis were explored with Poisson regression.

RESULTS

Clinical examiners correctly predicted the presence or absence of microbial recovery in 79 (76%) of 104 ulcerative keratitis cases and successfully distinguished among bacterial, fungal, and amebic keratitis for 54 (73%) of 74 culture-positive infections, although only 31 (42%) were subcategorized properly. The positive predictive value of clinical diagnosis was 65% (95% confidence interval [CI], 43% to 84%) for 20 eyes with Pseudomonas keratitis cases, 48% (95% CI, 32% to 63%) for 38 other bacterial keratitis, 45% (95% CI, 17% to 77%) for 13 fungal keratitis, and 89% (95% CI, 52% to 100%) for nine Acanthamoeba keratitis cases. The recognition of Pseudomonas keratitis significantly improved by the occurrence of a larger infiltrate (P = .02), and correctly predicting Acanthamoeba keratitis was enhanced by observing a ring infiltrate (P < .001). Antimicrobial use before referral significantly attenuated clinical diagnosis (P = .03) and hampered microbial recovery (P = .004).

CONCLUSIONS

Established Pseudomonas keratitis and Acanthamoeba keratitis can be suspected before laboratory confirmation, but overlapping inflammatory features and recent empiric antimicrobial treatment limits etiologic recognition of most microbial corneal infections.

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.

Classifying the Severity of Corneal Ulcers by Using the “1, 2, 3” Rule

PURPOSE

To propose and define the "1, 2, 3" rule as a system of categorizing the severity of bacterial keratitis and to determine its value in predicting the likelihood of visual loss after healing of bacterial corneal infection.

METHODS

Seventy patients were evaluated for infectious corneal ulcers by 2 cornea subspecialists (J.D.L., M.C.V.) at a tertiary facility between October 30, 2001, and November 1, 2004. Forty-one patients met the inclusion criteria. Visual acuities, ulcer characteristics, culture results, and treatment data were collected.

RESULTS

The sensitivity of the "1, 2, 3" rule for detecting potentially sight-threatening (PST) ulcers that would result in 0.20 logMAR (2 Snellen lines) or greater loss in best spectacle-corrected visual acuity (BSCVA) was 100%. The specificity of the "1, 2, 3" rule in correctly labeling an ulcer that did not cause vision loss as rarely sight threatening (RST) was 57.14%. The positive predictive value of the "1, 2, 3" rule was 28.57%. The negative predictive value of the "1, 2, 3" rule was 100%.

CONCLUSIONS

Corneal ulcers classified as PST are at significantly higher risk for sustaining loss of BCSVA compared with RST corneal ulcers. The "1, 2, 3" rule is sensitive and specific enough to be clinically useful in predicting which ulcers are more likely to have vision loss and which ulcers are not.

Failure of Listeria monocytogenes Keratitis to Respond to Topical Ofloxacin

PURPOSE

The purpose of this case report is to demonstrate the need for identification of the offending pathogen in bacterial keratitis to guide appropriate treatment.

METHODS

Case report.

RESULTS

We report a case of Listeria monocytogenes keratitis in a young healthy adult that failed to respond to standard empirical therapy for bacterial keratitis but was treated successfully with topical ampicillin, chloramphenicol, and systemic amoxicillin.

CONCLUSION

This case demonstrates the need for identification of the offending pathogen to guide appropriate treatment. It also demonstrates discrepancy between in vitro sensitivity and clinical response.