Trends in the etiology of infectious corneal ulcers at the F. I. Proctor Foundation.
OBJECTIVE
We analyzed laboratory results from corneal ulcers seen from 1976 to 1999 at the Francis I. Proctor Foundation, a referral center in San Francisco, to determine the relative frequencies of pathogens and to analyze for trends in frequencies of the most common pathogens. The results were compared with a previous study of corneal ulcers seen from 1948 to 1976 at the same institution.


METHODS
Ulcers presenting to the Proctor Foundation were Gram stained and cultured using standard techniques. Herpetic corneal ulcers were excluded from the study.


RESULTS
Organisms were isolated from 427 ulcers, 38% of all cases. Two hundred seventy-eight (59%) isolates were gram-positive bacteria, 145 (31%) gram-negative bacteria, 16 (3%) Acanthamoeba spp., and 36 (8%) fungi. Staphylococcus aureus was the most common organism, composing 20% of all isolates, followed by viridans group streptococci (12%), Streptococcus pneumoniae (11%), Pseudomonas aeruginosa (6%), Moraxella spp. (5%), and Serratia marcescens (4%). Over the 24-year study period the proportion of positive cultures decreased and the incidence of S. marcescens increased significantly. Comparing the period of 1948-1976 to 1976-1999, the frequency of S. pneumoniae and P. aeruginosa decreased, and that of S. marcescens increased significantly.


CONCLUSIONS
The common pathogens associated with corneal ulcers have changed over the past 50 years in Northern California, with S. pneumoniae and P. aeruginosa being isolated relatively less often and S. marcescens being isolated with increasing frequency. The decrease in isolation of organisms over the 1976-1999 period may have resulted from increasing empiric antibiotic treatment by referring ophthalmologists.
Varaprasathan
Gita
G
F. I. Proctor Foundation, University of California, San Francisco, San Francisco, CA 94143, USA.
Miller
Kevin
K
Lietman
Thomas
T
Whitcher
John P
JP
Cevallos
Vicky
V
Okumoto
Masao
M
Margolis
Todd P
TP
Yinghui
Miao
M
Cunningham
Emmett T
ET
D000048:Acanthamoeba / Q000302:isolation & purification*; D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D003320:Corneal Ulcer / Q000382:microbiology*; D015817:Eye Infections / Q000382:microbiology*; D005582:Foundations / Q000639:trends; D005658:Fungi / Q000302:isolation & purification*; D006785:Hospitals, University / Q000639:trends; D006801:Humans; D012017:Referral and Consultation; D012189:Retrospective Studies; D012495:San Francisco