C-179. Comparison of BBL CHROMagar Orientation/TSA II Biplate and Three Plate Media for Urine Cultures

A. Robinson, M. L. Majors, J. D. Claridge;
Sacred Heart Med. Ctr., Spokane, WA.

Urine cultures are one of the highest test volumes in microbiology, reflecting the high frequency of urinary tract infections. Given the manual nature of cultures and a technologist staffing shortage, potential methods to decrease labor merit evaluation. This study compared the BBL CHROMagar Orientation/TSA II biplate (COT) with the lab’s routine set-up of sheep blood, MacConkey, and colistin-nalidixic acid (CNA) agars, at 12 to 24 h and at 48 h incubation. Of the 197 urine cultures, 61 (31%) were no growth by both methods; 71 (36%) yielded one or two significant isolates; 63 (33%) were either mixed (> 3 organisms) or the colony count was too low to merit work up (< 1,000 CFU/mL). Discrepancies were considered minor if there were <2 log10 differences in colony count or isolates were present that were not clinically significant, such as in mixed cultures. There were a total of 22 (11%) minor discrepancies, including 7 associated with routine cultures and 15 with COT cultures. However, 14 of the 15 (93%) minor discrepancies with COT were cultures that contained mixed Gram-positive flora on the CNA plate in the conventional culture. These organisms were not seen on the COT, thus decreasing time spent working up clinically insignificant organisms. Discrepancies that could potentially impact patient care were categorized as major. These discrepancies occurred in cultures for which the other method was able to detect significant isolates that would have been missed. There were a total of 6 major discrepancies. All of the major discrepancies involved mixed cultures. Clinically significant isolates were not isolated in 4 (2%) of the routine cultures and 2 (1%) of the COT cultures. COT reduced spot tests by 46,600 for the annual volume of 70,000 urine cultures. Conversion to COT decreased urine culture set-up time by a third, associated biohazard waste by two thirds (from 6.7 to 2.3 metric tons or 44,636 L to 14,879 L annually), and associated refrigerator and incubator space by two thirds. Conversion to COT was a major paradigm shift for the technologists that was accomplished through a training guide and competency testing, thus achieving the outlined savings.