A comparison of antimicrobial regimen outcomes and antibiogram development in microbial keratitis: a prospective cohort study in Alexandria, Egypt

• Published in: Graefe's archive for clinical and experimental ophthalmology Vol. 262; no. 6; pp. 1865 - 1882
• Main Authors: Nayel, Amira A., Hamdy, Noha A., Massoud, Tamer H., Mohamed, Nelly M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2024; Springer Nature B.V
• Subjects: Acuity; Adult; Anti-Bacterial Agents - therapeutic use; Antimicrobial agents; Antimicrobial resistance; Bacteria - isolation & purification; Ceftazidime; Coagulase; Cornea; Cornea - microbiology; Egypt - epidemiology; Eye Infections, Bacterial - diagnosis; Eye Infections, Bacterial - drug therapy; Eye Infections, Bacterial - epidemiology; Eye Infections, Bacterial - microbiology; Eye Infections, Fungal - diagnosis; Eye Infections, Fungal - drug therapy; Eye Infections, Fungal - microbiology; Female; Follow-Up Studies; Fungi - isolation & purification; Gatifloxacin; Gentamicin; Gram-negative bacteria; Gram-positive bacteria; Humans; Keratitis; Keratitis - diagnosis; Keratitis - drug therapy; Keratitis - microbiology; Male; Medicine; Medicine & Public Health; Methicillin; Microbial Sensitivity Tests; Microorganisms; Middle Aged; Moxifloxacin; Natamycin; Ophthalmology; Prospective Studies; Treatment Outcome; Ulcers; Vancomycin; Visual Acuity; Voriconazole; Young Adult; Egypt; Fortified antibiotics; Empiric therapy; Corneal ulcers; Antibiogram; Ulcer healing; Time-to-epithelialization; Fungal keratitis; Antimicrobial resistance; Microbial keratitis; Bacterial keratitis
• ISSN: 0721-832X; 1435-702X; 1435-702X
• DOI: 10.1007/s00417-023-06362-0

Introduction Antimicrobial resistance in microbial keratitis has not been previously explored in Alexandria. We aim to recommend effective therapies through identification of etiological agents, determination of antimicrobial susceptibilities, and comparing outcomes of empiric topical antimicrobials. Methods In this 2022 prospective cohort conducted in Alexandria Main University Hospital cornea clinic, antimicrobial susceptibilities of isolated microorganisms from corneal scrapings were detected and antibiograms were developed. Bacterial (BK), fungal (FK), or mixed fungal/bacterial keratitis (MFBK) patients on empiric regimens were compared for ulcer healing, time-to-epithelialization, best-corrected visual acuity, interventions, and complications. Results The prevalent microorganisms in 93 positive-cultures were coagulase-negative staphylococci (CoNS, 30.1%), Pseudomonas aeruginosa (14%), and Aspergillus spp. (12.9%). CoNS were susceptible to vancomycin (VAN, 100%) and moxifloxacin (MOX, 90.9%). Gram-negative bacteria showed more susceptibility to gatifloxacin (90.9%) than MOX (57.1%), and to gentamicin (GEN, 44.4%) than ceftazidime (CAZ, 11.8%). Methicillin-resistance reached 23.9% among Gram-positive bacteria. Fungi exhibited 10% resistance to voriconazole (VRC). Percentages of healed ulcers in 49 BK patients using GEN + VAN, CAZ + VAN and MOX were 85.7%, 44.4%, and 64.5%, respectively ( p  = 0.259). Their median time-to-epithelialization reached 21, 30, and 30 days, respectively (log-rank p  = 0.020). In 51 FK patients, more ulcers (88.9%) healed with natamycin (NT) + VRC combination compared to VRC (39.1%) or NT (52.6%) ( p  = 0.036). Their median time-to-epithelialization was 65, 60, and 22 days, respectively (log-rank p  < 0.001). The VRC group required more interventions (60.9%) than NT + VRC-treated group (11.1%) ( p  = 0.018). In 23 MFBK patients, none healed using NT + CAZ + VAN, while 50% healed using VRC + CAZ + VAN ( p  = 0.052). Regimens had comparable visual outcomes and complications. Conclusion Based on the higher detected susceptibility, we recommend empiric MOX in suspected Gram-positive BK, gatifloxacin in Gram-negative BK, and GEN + VAN in severe BK. Due to better outcomes, we recommend NT + VRC in severe FK. Trial registration ClinicalTrials.gov identifier, NCT05655689. Registered December 19, 2022– Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05655689?cond=NCT05655689.&draw=2&rank=1