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.

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?

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.

RESULTS: DEMOGRAPHICS

Inclusion of 281 scrapings from 280 patients

140 males; 140 females

Average age 56,97 yrs

50,4% right eyes

2006-20082009-2011 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

RESULTS: RECOVERED PATHOGENS

2006-2008 2009-2011

N (%) N (%)

Gram Positive Isolates

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%) 9 (9.4%)

Serratia 3 (2.6%) 5 (5.2%)

Haemophilus 1 (0.9%) 4 (4.2%)

Fungal Isolates Candida 8 (7.0%) 5 (5.2%)

Aspergillus 2 (1.7%) 2 (2.1%)

Other 3 (2.6%) 1 (1.0%)

Acanthamoeba 6 (5.2%) 5 (5.2%)

Table 2: Prevalence of Cultured Microorganisms by Period

RESULTS: GRAM STAIN

2006-2008

2009-2011

Total Gram Positive (N) 115 85Total Gram Negative (N) 19 33

Ratio (G+:G-) 1:0.16 1:0.39

Table 3: Ratio of Gram Positive / Gram Negative Isolates

RESULTS: MONO- VS POLYMICROBIAL

2006-2008

2009-2011

Monomicrobial Isolates (%) 73.0% 72.9%Polymicrobial Isolates (%) 27.0% 27.1%

2006-2008 2009-2011Monomicrobial 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 4: Mono-/Polymicrobial Isolates by Period

Table 5: Etiology of Mono-/Polymicrobial Isolates by Period

RESULTS: SENSITIVITY TO ANTIBIOTICS

Table 6: In Vitro Sensitivity to Antibiotics by Period

RESULTS: SENSITIVITY TO ANTIBIOTICS

Imipenem

Ceftazidime

Ofloxacin

Ciprofloxacin

Moxifloxacin

Gentamicin

Tobramycin

Amicacin

Chloramphenicol

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%100%

2006-08 2009-11

In Vitro Sensitivity

Vancomycin

Oxacillin

Imipenem

Ceftazidime

Ofloxacin

Ciprofloxacin

Moxifloxacin

Gentamicin

Tobramycin

Chloramphenicol

Erythromycin

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%100%

2006-08 2009-11

In Vitro Sensitivity

Table 8: In Vitro Sensitivity of Gram Positive Isolates to

Antibiotics

Table 9: In Vitro Sensitivity of Gram Negative Isolates to

Antibiotics

RESULTS: SENSITIVITY TO ANTIBIOTICS

CNS MoraxellaOfloxacin 65,4% 100,0%Ciprofloxacin 65,4% 100,0%Moxifloxacin 80,8% 100,0%Gentamicin 84,0% 100,0%Tobramycin 84,6% 100,0%

Table 10: Sensitivity of Most Prevalent Gram Positive and Gram Negative Species to Empirically

Used Antibiotics

RESULTS: CONTACTLENS ASSOCIATION

CL 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 2,3% 8,3%

Total Gram Positive 46,5% 74,8%

Gram Negative Isolates %

Pesudomonas 14,0% 2,9%

Moraxella 2,3% 6,6%

Serratia 4,7% 1,2%

Haemophilus 0,0% 0,8%

Total Gram Negative 20,9% 17,8%

Fungal Isolates %

Candida 7,0% 4,1%

Aspergillus 2,3% 1,2%

Other 2,3% 1,2%

Total Fungal 11,6% 6,6%

Acanthamoeba 20,9% 0,8%

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.