Determination of Optimal Urine Culture Criteria

The criteria for setting up a urine culture are different based on the institution where the sample is collected. At Spectrum Health Ludington Hospital (SHLH), a urine culture is set up when the sample is determined to have one of the following: six or more white blood cells (WBC) per microscopic high power field (HPF), greater than “few” bacteria, or positive nitrite. Meeting these criteria may indicate a urinary tract infection (UTI). A culture is not set up if the sample is considered contaminated, which is defined as having at least five squamous epithelial cells per HPF. The objective of this study was to determine if these criteria are ideal or if they should be altered. The staff of SHLH suspect that too many cultures are being set up, causing time, effort, and money to be wasted. The most recent 277 clean catch midstream or catheter samples were collected between inpatient and outpatient populations, analyzed routinely on the CLINITEK Atlas and Sysmex UF-1000i analyzers, deidentified, and organized chronologically. The culture plates that were set up based on current criteria were inspected to determine if urinary tract infection causing pathogens were predominant (\u3e100,000 colony forming units per milliliter). Of the 277 urine cultures analyzed, 124 were determined to be positive for UTI causing pathogens while 153 were determined to be negative for such organisms. The cultures that were negative for pathogenic organisms can be deemed unnecessary and wasteful. Evaluation of SHLH’s current reflex criteria showed that less than 45% of the urine cultures set up yielded a positive culture with the presence of a pathogenic organism