1. Epidemiology of Infectious Corneal Ulcers at Tertiary Centers in Vancouver, BC
Karolien Termote, Aaron W Joe, Andrea L Butler, Simon J Holland, Sonia N Yeung
None of the authors have a financial interest in the subject matter of this poster.

2. Purpose
To study the epidemiology of cultured infectious corneal ulcers in Vancouver, BC, Canada.
Which are the most frequent pathogens?
What is their sensitivity profile?
Which pathogens are associated with contactlens wear?

3. Methods
This is a multicenter, retrospective, observational case series and chart review.
Predetermined search terms were entered into the hospitals’ electronic microbiology databases to create a cohort of patients that had undergone corneal scrapings for ulcers from April 2006 to March 2011.
All specimens were plated on culture media. Cultured species were identified, and antimicrobial sensitivities were performed.
Clinical charts were then reviewed to identify associated contactlens wear.

4. Results: demographics
Inclusion of 281 scrapings from 280 patients
140 males; 140 females
Average age 56,97 yrs
50,4% right eyes
Total
Corneal cultures (N)
153
128
281
Positive cultures (N)
115 96
211
Recovery (%)
75,2%
75,0%
75,1%
Table 1: Culture Recovery Rate

5. Results: recovered pathogens N
(%)
Positive
Isolates
Gram
S. epidermidis / CNS 40
(34.8%) 39
(40.6%)
Staph aureus 25
(21.7%) 9
(9.4%)
Streptococcus 19
(16.5%) 16
(16.7%)
Corynebacterium 13
(11.3%) 8
(8.3%)
MRSA 3
(2.6%) 2
(2.1%)
Gram Negative Isolates
Moraxella 7
(6,1%) 10
(10.4%)
Pseudomonas 4
(3,5%)
Serratia 5
(5.2%)
Haemophilus 1
(0.9%)
(4.2%)
Fungal Isolates
Candida
(7.0%)
Aspergillus
(1.7%)
Other
(1.0%)
Acanthamoeba 6
Table 2: Prevalence of Cultured Microorganisms by Period

6. Table 3: Ratio of Gram Positive / Gram Negative Isolates
Results: Gram Stain
Total Gram Positive (N)
115 85
Total Gram Negative (N) 19 33
Ratio (G+:G-)
1:0.16
1:0.39
Table 3: Ratio of Gram Positive / Gram Negative Isolates

7. Results: Mono- vs Polymicrobial
Monomicrobial Isolates (%)
73.0%
72.9%
Polymicrobial Isolates (%)
27.0%
27.1%
Table 4: Mono-/Polymicrobial Isolates by Period
Monomicrobial G+ Isolates (%)
67,2%
49,8%
Monomicrobial G- Isolates (%)
15,1%
34,2%
Monomicrobial Acanthamoeba (%)
7,1%
5,7%
Polymicrobial with G+ (%)
97,0%
96,6%
Polymicrobial with G- (%)
15,9%
27,8%
Polymicrobial with Acanthamoeba (%) 0%
3,8%
Table 5: Etiology of Mono-/Polymicrobial Isolates by Period

8. Results: sensitivity to antibiotics
Table 6: In Vitro Sensitivity to Antibiotics by Period

9. Results: sensitivity to antibiotics
Table 8: In Vitro Sensitivity of Gram Positive Isolates to Antibiotics
Table 9: In Vitro Sensitivity of Gram Negative Isolates to Antibiotics

10. Results: sensitivity to antibiotics
CNS
Moraxella
Ofloxacin
65,4%
100,0%
Ciprofloxacin
Moxifloxacin
80,8%
Gentamicin
84,0%
Tobramycin
84,6%
Table 10: Sensitivity of Most Prevalent Gram Positive and Gram Negative Species to Empirically Used Antibiotics

11. Results: contactlens associationCL
non-CL
Gram Positive Isolates %
Staph aureus
0,0%
14,0%
MRSA
2,3%
1,7%
S. epidermidis / CNS
25,6%
28,1%
Streptococcus
9,3%
12,8%
Corynebacterium
8,3%
Total Gram Positive
46,5%
74,8%
Gram Negative Isolates %
Pesudomonas
2,9%
Moraxella
6,6%
Serratia
4,7%
1,2%
Haemophilus
0,8%
Total Gram Negative
20,9%
17,8%
Fungal Isolates %
Candida
7,0%
4,1%
Aspergillus
Other
Total Fungal
11,6%
Acanthamoeba

12. Conclusion
Positive culture results were most commonly Gram positive bacteria, followed by Gram negative bacteria, then fungi, and finally parasites.
We found an increase in Gram negative isolates over time, both in mono- and polymicrobial ulcers.
General sensitivity to moxifloxacin, gentamicin and oxacillin decreased over time.
Frequently empirically used antibiotics have poorer coverage for Gram positive isolates than for Gram negative isolates.
Contactlens related ulcers were, in comparison to non contactlens related ulcers, more often caused by Gram negative pathogens, fungi and Acanthamoeba species.