Effects of storage time on urine culture

Abstract

Background: Urinary tract infections are among the most prevalent infections, affecting approximately 150 million people worldwide annually. These infections are caused by Gram-negative and Gram-positive bacteria, as well as certain fungi. In the United States, approximately 7 million individuals seek medical attention each year due to various ailments. Of these cases, around 1 million are diagnosed with urinary tract infections (UTIs), with the majority being cases of acute cystitis, and approximately 250,000 diagnosed with acute pyelonephritis. UTIs rank as the most common infections among outpatients, and notably, one in three women receive antibiotics for UTIs by the age of 24. An estimated 50-60% of adult women who require treatment have experienced UTIs at some point in their lives. The diagnosis of UTIs relies on a comprehensive evaluation that includes general urinalysis, microscopic examination, and urine culture tests. In essence, UTIs are determined by the qualitative analysis of urine quality. Urine specimens are susceptible to contamination, which may include the presence of epithelial cells, peritoneal cells, and vaginal cells. Implementing meticulous pre-test measures, such as proper urine collection, storage, and transportation, represents the most effective approach to mitigate these potential contaminations. It is imperative that urine specimens be tested within two hours of collection unless refrigerated or stored with a suitable preservative to minimize the risk of bacterial growth. This approach is believed to directly impact the occurrence of false-positive results, promote judicious antibiotic use, and reduce overtreatment. Aim: To determine the relationship between the storage time of the analytes, which is an error in the pre-analysis phase, based on the analysis of the quality of urine. Materials and Methods: Based on the test results of customers who performed urinalysis at the central laboratory of clinical pathology of First Central Hospital Mongolia, between from October 8, 2020 to February 10, 2021. 61 samples were selected by random sampling, and the samples were subjected to detailed urine analysis and bacteriological analysis at 1, 2, and 3 hour intervals, and the results were compared. Results: Nitrite concentration did not show any change within 3 hours. According to bacteriological analysis, 42.8% of the samples with bacterial growth of 103 CFU/ml showed no bacterial growth within 3 hours, 28.5% of the samples increased to 104 after 2 hours, and 28.5% of the samples increased to 104 CFU/ml after 3 hours. However, 9.0% of all samples without bacterial growth were contaminated with bacterial growth of 103 CFU/ml after 2 and 3 hours. Conclusions: 1. No difference in nitrite concentration was observed when urine was stored at room temperature for 1 and 3 hours. 2. Comparison between urine culture results at 1 and 3 hours, it showing that bacterial culture after 3 hours, indicating contamination.