Medical management approach to infectious keratitis

Abstract

This section provides guidelines on medical therapy of patients with infectious keratitis. In addition to initial empirical therapy, preferred medications, once the organisms responsible are isolated, are discussed. Atypical mycobacterial keratitis following lasik is described. General guidelines for supportive therapy and follow-up, of these patients are presented. Clinical response to treatment and indications for intervention are discussed. Possible causes and approach to cases refractory to medical therapy are discussed.

Pathogenesis of microbial keratitis

“…Basically, no single antibiotic is effective against all bacterial keratitis-causing organism and therefore an agent having broad spectrum activity covering both, gram negative and gram positive organisms is desirable. Broadly speaking, two treatment options are available; fluoroquinolones monotherapy and/or combination therapy of fortified antibiotics including cefazolin and tobramycin or gentamicin [51]. The aminoglycosides in fortified drops provides excellent coverage against gram-negative organisms and are also active against Staphylococci and some Streptococci.…”

“…The frequency of application of antibiotic drops depends on the severity of infection but usually they are administered every half an hour for the first 24-36 h [51,133]. In severe cases, an initial loading dose is achieved via a drop every 5 min for the first 30 min.…”

“…The therapy is then tapered off gradually based on the clinical response of the patient. Other antibiotics used include amikacin, vancomycin, methicillin, clotrimoxazole, and clarithromycin depending on the causative agent responsible for keratitis [51].…”

“…The use of corticosteroids as anti-inflammatory agents are controversial and are best avoided until the infection is completely eradicated or at least under control [51,133]. In patients with corneal ulceration the use of non-steroidal anti-inflammatory drugs should also be avoided due to increased risk of corneal melting and perforation.…”

“…In case of progressive corneal thinning or perforations, less than 2 mm cyanoacrylate tissue adhesives may be used, which may also have some inherit antibacterial activity as well [41,51,93,133]. Tissue adhesives are only suitable for small perforations, as they are toxic to corneal endothelium.…”