C-213. The Impact of Chromagar on the Time to Identification of Yeast Positive Blood Cultures

M. Sholtis, M. Wnek, S. Schindler, D. Warner, G. S. Hall;
Cleveland Clin., Cleveland, OH.

Background: The morbidity and mortality caused by yeast fungemia is a significant problem. C. albicans (CA) represents about 50% of fungemia cases, with majority of remaining 50% being caused by C. glabrata (CG), C. parapsilosis (CP), and C. tropicalis (CT). CA are predictably susceptible to most anti-fungals, however, the non-CA species are often more resistant. The rapid identification of the specific Candida species involved can help the clinician choose the most efficacious drug treatment in a cost effective manner. Our clinical microbiology laboratory has chosen to include Chromagar Candida© (CHROM) (BD Microbiology Systems, Sparks, MD) in the planting battery of yeast positive blood cultures. We have evaluated the impact of this agar on time to full species identification by comparing 50 yeast blood cultures planted with CHROM (in 2007) to 50 yeast positive blood cultures planted when we were not using CHROM (2006). Methods: When yeasts are identified in blood culture bottles, Columbia Blood Agar (BAP) , Potato Dextrose Agar (PDA) (and since 4/2007, CHROM) are planted; the positive gram stain result is called to the clinician. The specific identification follows when completed, using a combination of microscopic observations, CHROM and biochemicals. Fifty consecutive blood cultures positive for yeasts other than Candida albicans were examined for time between initial gram stain report and identification without the use of CHROM. Fifty consecutive non-CA yeasts were examined with CHROM in the planting battery. No other changes were made during this period. Results:

Yeast ID

# isolated w/o
CHROM

# isolated with
CHROM

Time to ID
w/o CHROM
(in days)

Time to ID with
CHROM
(in days)

C glabrata

30

17

4.4

2.9

C parapsilosis

11

15

5

3.8

C tropicalis

4

7

3.5

2.4

C krusei

1

6

4

2

Candida sp
(infrequent isolates)

4

5

6

3.75

Conclusion The use of CHROM in the planting battery of yeast positive blood cultures resulted in an overall decrease of time to identification from 4.6 days to 3 days. This change is statistically significant (p=<0.0001) and justifies our decision to use CHROMAGAR on a routine basis.