• Anatomy

Microbial keratitis is a major cause of corneal opacity and loss of vision worldwide, and topical antimicrobial therapy is a critical component in its management. The study by Austin et al 1 found that there are regional variations in practice patterns influenced by concern over availability and toxicity versus broad-spectrum coverage and resistance. Respondents in the USA were more likely to treat with fortified antibiotics than their international peers.1

This raises some important points and questions in the treatment of suspected bacterial keratitis.

Why do some clinicians opt for monotherapy and others fortified antimicrobials? What is understood by combination therapy? What are the treatment considerations when the microbiological report says susceptible or resistant?

The clinical outcome in microbial keratitis is dependent on host factors, the virulence of the infecting bacteria and the minimum inhibitory concentration (MIC) of the antimicrobial against the respective bacteria.2–4 The MIC is used to determine susceptibility criteria in order to choose an appropriate antimicrobial for treatment.5–7 Although there is a relationship between clinical outcome and the MIC of antimicrobials in microbial keratitis, the actual MICs of the available antimicrobials against the respective isolate …