Efficacy of a Novel Antibiotic Drug Combination Toward Multidrug-Resistant Ocular Pathogens.

PURPOSE: Antimicrobial resistance is a global health threat, compounded by the reduction in the discovery of new antibiotics. A repurposed drugs-based approach could provide a viable alternative for the treatment of multidrug-resistant (MDR) bacterial infections. In this study, we sought to evaluate the in vitro efficacy of a novel drug combination, polymyxin B/trimethoprim (PT) + rifampin on MDR isolates from patients with bacterial keratitis in India. METHODS: Forty-three isolates, which included 20 Staphylococcus aureus , 19 Pseudomonas aeruginosa , 3 Pseudomonas stutzeri , and 1 Acinetobacter baumannii , were evaluated for their antibiotic resistance by minimum inhibitory concentration (MIC). Fractional Inhibitory Concentration Index (FICI) testing was performed to measure the antimicrobial impact of PT + rifampin in combination. RESULTS: Among S. aureus isolates, 100% were resistant to at least 1 antibiotic class, 12 (60%) were MDR, and 14 (70%) were classified as methicillin-resistant. Among the gram-negative isolates, >90% were classified as MDR. Fractional Inhibitory Concentration (FIC) testing revealed that PT + rifampin was effective in completely inhibiting growth of all isolates while also displaying additive or synergistic activity in approximately 70% of the strains. Mean FICI values were 0.753 ± 0.311 and 0.791 ± 0.369 for S. aureus and gram-negative isolates, respectively, and a >2-fold reduction in MIC was measured for both PT and rifampin when tested in combination versus alone. CONCLUSIONS: Our data demonstrate the ability of PT + rifampin to eliminate all isolates tested, even those conferring MDR, highlighting the promise of this drug combination for the treatment of bacterial keratitis.

Bilateral Severe Herpes Simplex Endotheliitis with a Possible Association with Latanoprost.

PURPOSE: To report bilateral Herpes Simplex virus (HSV) keratitis in a patient on latanoprost for primi]k=8ary open angle glaucoma (POAG). METHODS: Case report. RESULTS: A 76-year-old healthy male on latanoprost monotherapy for POAG polresented with sudden bilateral decreased vision. Examination showed bilateral dense corneal edema with loose epithelium. Aqueous fluid was positive for HSV-1 DNA on polymerase chain reaction (PCR). Latanoprost was discontinued, topical prednisolone acetate 1% eye, acyclovir 400 mg 5 times a day and combination of dorzolamide hydrochloride 2% and timolol maleate 0.5% twice daily were prescribed. The vision rapidly improved to 20/25 along with complete resolution of corneal edema within four weeks, with no recurrences over the next one year. CONCLUSION: Bilateral simultaneous HSV endotheliitis is a rare condition and positive PCR test can help rule in the diagnosis. HSV keratitis is a known adverse event with Latanoprost use and can present atypically.

Microbiology Profile of COVID-19-Associated Rhino-Orbital Mucormycosis Pathogens in South India.

This study describes the microbiological and histopathological features of patients with COVID-19-associated rhino-orbital mucormycosis (ROM) seen at the L V Prasad Eye Institute between May and August 2021. Diagnosed clinically and radiologically, 24 patients with ROM were included in the study. Deep nasal swabs or endoscopically collected nasal swabs or orbital tissues were submitted for microbiological evaluation and in vitro susceptibility testing by microbroth dilution for natamycin, amphotericin B, caspofungin, posaconazole, ketoconazole, and voriconazole. Cultures were processed by 28S ribosomal DNA polymerase chain reaction and molecular sequencing. A portion of orbital tissues was also sent for histopathological evaluation. The age of the patients ranged from 27 to 75 (mean 48.58 ± 14.09) years and the majority (79%) were male. Nineteen patients were known to be diabetic prior to developing ROM and 18 patients had recovered from active COVID-19 infection. Thirteen patients had a history of hospitalization during COVID-19 infection and eight received steroids. Of the 24 samples, microbiological evaluation identified Rhizopus arrhizus in 12, Rhizopus microsporus in 9, Lichtheimia ramosa in 2, and Rhizopus delemar in 1. Twelve isolates were tested for antifungal susceptibility and all were susceptible to natamycin and amphotericin B. The susceptibility to posaconazole was high, with minimum inhibitory concentration (MIC) < 2 µg/mL for 10/12 (84%) isolates, whereas the MIC of other drugs varied. Histopathological examination of tissues showed acute fulminant disease, granuloma formation, and vascular invasion by the fungal pathogens in these specimens. Rhizopus arrhizus was predominantly associated with ROM and most isolates were susceptible to amphotericin B and posaconazole. Further studies are needed to corroborate the findings and explain possible underlying links.

Trends in the Microbiological Spectrum of Nonviral Keratitis at a Single Tertiary Care Ophthalmic Hospital in India: A Review of 30 years.

PURPOSE: The aims of this study were to assess the trends in microorganisms from patients with infectious keratitis and to assess their antibiogram patterns at a tertiary eye care center in India. METHODS: In this retrospective observational case series, microbiological records of all corneal ulcers were reviewed from 1991 to 2020 and assessed for trends in keratitis and antibiotic susceptibility using the χ 2 test. RESULTS: Of the total of 51,747 patients, 51.13% were culture positive. A decrease in bacteria was noted from 56% to 38%, with a parallel increase in fungal isolates from 24% to 51%. Gram-positive bacteria accounted for 70.8% of the total bacteria, a trend in rise of Streptococcus pneumoniae (31%) and a decreasing trend in prevalence of Staphylococcus epidermidis was observed over 30 years . Pseudomonas aeruginosa (55.5%) was the most prevalent gram-negative pathogen, whereas Fusarium spp . (33.1%) and Aspergillus spp. (32.4%) were the most common fungal isolates. The susceptibility of gram-positive organisms to cefazolin decreased from 95.5% to 66% ( P = 0.0001), amikacin from 88% to 55% ( P = 0.0001), and vancomycin from 98.9% to 90.7% ( P < 0.05). A similar decrease in susceptibility was also significant for gram-negative organisms with piperacillin/tazobactam and chloramphenicol ( P < 0.05). A significant trend toward increasing resistance against fluoroquinolones was also observed for ciprofloxacin (gram-positive organisms: 16% to 50%; gram-negative organisms: 11.5% to 18.7%), gatifloxacin (38% to 47%), and moxifloxacin (9.4% to 29%). CONCLUSIONS: The spectrum of keratitis has changed, and fungus is now the predominant etiology. An increasing trend in resistance to all antibiotics studied would affect the empiric treatment, also suggesting regular surveillance.

CULTURE POSITIVITY RATES OF DEEP VITREOUS BIOPSY UNDER AIR VIS-À-VIS CONVENTIONAL ANTERIOR VITREOUS BIOPSY IN ENDOGENOUS ENDOPHTHALMITIS.

PURPOSE: To describe the comparison of the culture positivity rates of deep vitreous biopsy under air and conventional anterior vitreous biopsy in endogenous endophthalmitis. MATERIALS: A retrospective, consecutive, comparative series including cases of endogenous endophthalmitis from January 2014 to January 2021. They were divided into those where conventional anterior vitreous biopsy was taken and those where a deep biopsy was taken under air (DBA group). The culture positivity rate among the two groups was compared, and factors affecting the same were analyzed by a regression analysis. RESULTS: There were 140 eyes in the conventional anterior vitreous biopsy group and 44 eyes in the DBA group. Sex, age, duration of symptoms, underlying systemic illness, presenting vision in logMAR, and total number of vitreous interventions were comparable between the two groups. Visual outcome was better in patients undergoing DBA as compared with those who underwent conventional anterior vitreous biopsy , (1.28 ± 1.01 logMAR, 20/380 vs. 1.88 ± 1.33 logMAR, 20/1,500, P = 0.03). No case in the DBA group developed retinal detachment or any complication attributable to the technique. In the conventional anterior vitreous biopsy group, the culture positivity was seen in 43/140 samples (30.71%), and in the DBA group, it was noted in 29/44 samples (65.9%). Taking a DBA was the only factor that was significant both in bivariate (odds ratio 4.36, 95% confidence interval 2.12-8.95, P < 0.0001) and multivariate analysis (odds ratio 4.02, 95% confidence interval 3.1-7.43, P < 0.0001). CONCLUSION: Vitreous sampling can be performed from the deep vitreous cavity in endogenous endophthalmitis safely and effectively under air infusion, improving the culture positivity rates.

Elucidating the clinical, microbiological and molecular diagnostic aspects of Macrophomina phaseolina keratitis.

This study reports the clinico-microbiological features of Macrophomina phaseolina keratitis. Clinically diagnosed as microbial keratitis, six patients underwent microbiological evaluation. Fungal culture isolates from cornea were subjected to DNA sequencing of the ITS region, phylogenetic analysis and reconfirmation by polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) of six antifungal drugs were determined by microbroth dilution method against the six isolates. All patients were treated with antifungals. Failed medical therapy necessitated therapeutic penetrating keratoplasty (TPK). Corneal buttons were processed for histopathology. In all patients, the corneal scraping showed septate hyaline fungal filaments. The BLAST analysis for ITS sequences of all six fungal isolates suggested M. phaseolina, however, when limited to sequences from type material, they matched M. pseudophaseolina. Phylogenetic analysis could not differentiate between these two species and clustered in a single clade. PCR assay of specific gene sequence [MpCal (calmodulin)] reconfirmed all isolates as M. phaseolina. The MICs of voriconazole and posaconazole were lowest (0.03 to 2 and 0.1 to 2µg/mL respectively) and all isolates were susceptible to natamycin. Except for case 1, which healed with a scar on treatment, all other cases worsened, despite medical treatment, necessitating TPK. Histopathology of 3 out of 4 buttons showed the presence of fungal filaments. While direct microscopic examination of corneal scrapings is helpful in diagnosis, identification of M. phaseolina in culture is challenging. Although MICs of commonly used antifungals are low response to medical therapy is not encouraging; patients may require TPK for resolution of infection in M. phaseolina keratitis.

DNA sequencing, phylogenetic analysis and specific PCR confirmed Macrophomina phaseolina keratitis in six patients. Although antifungal susceptibility showed the organisms to be susceptible to natamycin five patients did not respond to treatment and needed keratoplasty.

Clinical Outcomes of Rose Bengal Mediated Photodynamic Antimicrobial Therapy on Fungal Keratitis with Their Microbiological and Pathological Correlation.

PURPOSE: To report the clinical outcome of Photodynamic Antimicrobial Therapy (PDAT) with Rose Bengal (RB) used as an early adjuvant therapy in patients with fungal keratitis and their microbiological and pathological correlation. METHODS: Patients with microbiologically confirmed fungal keratitis underwent PDAT-RB along with topical natamycin 5% drops hourly and oral ketoconazole 200 mg twice a day. This was performed by applying rose bengal (0.1%) to the de-epithelialized cornea for 30 minutes, followed by irradiation with a 6 mW/cm2 custom-made green LED source for 15 minutes (5.4 J/cm2). The corresponding fungal isolates were tested in vitro using PDAT-RB and corneal buttons were evaluated for correlation. RESULTS: Following informed consent, seven patients (male-5, female-2, mean age 47.7 years) with fungal keratitis were recruited. There were 3 cases each of Fusarium and Aspergillus flavus and 1 case of Acremonium sp. The average vertical and horizontal diameters of the corneal infiltrate were 4.12 ± 0.55 and 3.99 ± 1.19 mm, respectively. The average depth of corneal involvement was 283 ± 75.27µ as measured by anterior segment OCT. The clinical resolution was achieved in the cases with Fusarium keratitis with an average time of 39 days. Three cases of A. flavus and a single patient with Acremonium keratitis worsened and needed therapeutic keratoplasty (TPK) for resolution. Post-TPK, the corneal tissues grew A. flavus in one out of three cases and Acremonium sp. in one case. In vitro PDAT-RB experiment was performed on the corresponding fungal isolates grown from the corneal scraping. PDAT-RB produced clear inhibition of Fusarium and Acremonium sp. with no effect on the growth of A. flavus. Histopathologically, 2 out of 4 (50%) corneal buttons showed fungal filaments. CONCLUSIONS: While the in vitro and in vivo results of PDAT-RB matched for Fusarium sp. and Aspergillus flavus keratitis being favourable in the former and non-favourable in the latter, these results were discrepant in Acremonium sp.

Herpes Simplex Virus Anterior Uveitis in a Child Presenting as a Hypopyon in a White Eye.

PURPOSE: To report a rare ocular presentation of unilateral anterior uveitis with hypopyon in a 5-year-old child, suspected as masquerade. METHODS: Retrospective report. RESULTS: A 5-year-old boy presented with hypopyon-uveitis. Detailed systemic work-up was negative for masquerade and uveitis entities. He was started on oral and topical steroids but had reactivation on taper. Real-time polymerase chain reaction (PCR) test of aqueous fluid was positive for herpes simplex virus (HSV)-1 DNA. The inflammation resolved completely on oral acyclovir and topical corticosteroids. He subsequently underwent pars plana lensectomy, primary posterior capsulotomy and vitrectomy for complicated cataract. Post-operatively, vision improved to 20/400 with aphakic correction. Maintenance oral acyclovir was stopped after 3 months with no reactivation and amblyopia therapy was continued. CONCLUSION: This is a rare presentation of hypopyon uveitis due to HSV-1 in a child. The role of real-time PCR in establishing the diagnosis is crucial in such cases of diagnostic dilemma.