Researchers from the University of Pittsburgh may have unearthed the predominant underlying causes of three ocular infections, and in turn created a roadmap for the development of new antimicrobials to treat these diseases. Their study, published in Eye & Contact Lens, combed through more than 3,000 cases of keratitis, endophthalmitis and conjunctivitis gathered over a 26-year period and looked for the prevalence of bacteria, fungi, viruses and Acanthamoeba in the collective samples.

Since 1993, investigators at the school’s Charles T. Campbell Eye Microbiology Laboratory, which routinely diagnoses ocular infectious disease, have stocked pathogens and patient samples isolated for keratitis, conjunctivitis and endophthalmitis for exploration of new testing and treatments.

The study found the following ocular pathogen trends:

  • Keratitis: Researchers analyzed 1,387 samples that were gathered from 2004 to 2018. They reported bacteria was the main infectious agent at 72.1% (Staphylococcus aureus 20.3%, Pseudomonas aeruginosa 18%, Streptococcus spp. 8.5%, other gram-positives 12.4% and other gram-negatives 12.9%), followed by herpes simplex virus at 16%, fungi 6.7% and Acanthamoeba at 5.2%.
  • Endophthalmitis: Out of the 770 endophthalmitis cases gathered from 1993 to 2018, the study found coagulase-negative Staphylococcus at 54%, Streptococcus spp. at 21%, S. aureus at 10%, other gram-positives at 8% and gram-negatives at seven percent.
  • Conjunctivitis: This collection included 847 conjunctivitis cases gathered from 2004 to 2018. Investigators noted the following distributions: adenovirus at 34%, S. aureus at 25.5%, Streptococcus pneumoniae 9%, Haemophilus 9%, other gram-negatives 8.8%, other gram-positives 6%, coagulase-negative Staphylococcus 4.5% and Chlamydia 3.2%.

The prevalence of ocular pathogens as infections of keratitis, endophthalmitis and conjunctivitis/blepharitis have never been reported in relation to each other (bacteria, viruses, fungi and parasites), says investigator Regis P. Kowalski, MS, M(ASCP), who is executive director of the lab. “Our data creates an awareness of the different infectious etiologies, importance of laboratory studies and future treatment requirements for infectious ocular disease,” Dr. Kowalski says.

The cases represent all positive cultures from outpatient clinics, in-house private practices, emergency department and surgical centers, satellite offices, community ophthalmologists and patients sent to the ophthalmic microbiology lab for cultures and studies.

Kowalski RP, Nayyar SV, Romanowski EG, et al. The prevalence of bacteria, fungi, viruses, and Acanthamoeba from 3,004 cases of keratitis, endophthalmitis, and conjunctivitis. Eye & Contact Lens. August 1, 2019. [Epub ahead of print].