This study is an observational prospective cohort study which aims to generate an antibiogram and to assess the clinical responses and outcomes of microbial keratitis patients, treated with empiric topical antimicrobial therapies, with the main objective being to recommend the most effective empiric therapy. Microbial keratitis patients are attending the Cornea Outpatient Clinic at Alexandria Main University Hospital, Alexandria, Egypt.

The main objective of this observational study is to recommend the most effective empiric topical antimicrobial therapy in microbial keratitis, according to the current local antimicrobial resistance data and the clinical outcomes of patients with bacterial, fungal, and mixed bacterial and fungal keratitis being treated with different empiric topical antibiotics and antifungal therapies.

In the study, test results of routinely performed culture and sensitivity on corneal scraping samples and on contact lenses in indicated severe, centrally located, and large ulcers are collected and analyzed. The sensitivity data is utilized to generate an antibiogram to describe the local prevalence of bacteria and fungi causing microbial keratitis and to investigate the prevalence of antimicrobial resistance.

Results of the culture and sensitivity are often delayed, hence empiric broad- spectrum antimicrobial therapy is ideally started after corneal scraping, until laboratory test results are obtained. Broad-spectrum empiric therapy will be modified into a more selective culture- guided therapy if the causative agent and its antimicrobial sensitivity are identified.

Empiric therapy continues in cases where the culture results are negative together with clinical improvement. Also, when patients have already been on empiric treatment before presenting to the clinic, corneal scraping and culture are not performed.

In the study, microbial keratitis patients diagnosed as either bacterial, fungal, or mixed bacterial and fungal keratitis, taking the empiric topical antimicrobials, are observed. The study investigator 's role is to observe and study the clinical responses and treatment outcomes of microbial keratitis patients who are on different empiric antimicrobial therapies as part of the routine medical care. There is no assignment of any intervention to the study participants. The investigator does not intervene, and does not prescribe, recommend, or assign any intervention to the study participants.

The clinical response of microbial keratitis patients, who are on different empiric antibiotics and antifungal eye drops, is studied by determining the primary and secondary outcomes. Measured outcomes include corneal ulcer healing, time to epithelialization, improvement in visual acuity, rates of surgical interventions and complications.

Inclusion Criteria:

• Patients diagnosed with bacterial keratitis either clinically or by culture.
• Patients diagnosed with fungal keratitis either clinically or by culture.
• Patients diagnosed with mixed bacterial and fungal keratitis either clinically or by culture.

Exclusion Criteria:

• Patients diagnosed with corneal abrasions and non-infectious corneal ulcers.
• Patients diagnosed with acanthamoeba keratitis as a single causative agent.
• Patients diagnosed with viral keratitis as a single causative agent.
• Patients who are noncompliant to treatment.

Bacterial keratitis, fungal keratitis, and mixed bacterial and fungal keratitis patients attending the Cornea Outpatient Clinic at Alexandria Main University Hospital.