Even with safer contact lens products and more frequent lens replacement, contact lens wear is still the main risk factor for Pseudomonas-related microbial keratitis, according to a Taiwanese study that tracked trends in this condition over two decades. Additionally, the investigation found an increased antibiotic resistance among certain organisms.

Researchers reviewed records of patients with microbial keratitis who were hospitalized at the National Taiwan University Hospital between 2007 and 2016. They compared demographics, predisposing factors, pathogens and clinical courses with the results of their previous study conducted from 1992 to 2001. Antiobiotic susceptibility was also compared with their findings from 1994 to 2005.

The study found chronic disorder–related microbial keratitis was on the rise, along with an increasing trend of oxacillin-resistance in Staphylococcus species.

Also of note, researchers reported a decreasing trend in nontuberculous mycobacteria keratitis, while Microsporidia keratitis was found to be an emerging ocular disease. Though gram-negative isolates remained susceptible to all antibiotics tested, antibiotic resistance was more common in gram-positive isolates, investigators said.

Other trends included:

• A rise in the percentage of patient 60 years and older with microbial keratitis
• A decline in the proportion of trauma-related microbial keratitis
• An increase in chronic ocular or systemic disorder cases

Researchers found the most common bacterial isolates were Pseudomonas aeruginosa (35.2%) and Staphylococcus species (13.2%), and management of these infections did not differ between the two decades. They also found the susceptibility of Staphylococcus species to oxacillin reduced significantly, and an increase in Methicillin-resistant Staphylococcus aureus keratitis was also observed.