Evaluation of BD Vacutainer Plus Urine C&S Preservative Tubes
Evaluation of BD Vacutainer Plus Urine C&S Preservative Tubes
A total of 110 urine specimens were included in this study. Seventy-four urine samples were obtained from female patients (67%) and 36 urine samples were from male patients (33%). Patients ranged in age from 17 to 95 years, with an average age of 57 years. The average time between the collection of the urine specimen and its arrival in the laboratory was 25 minutes (range, 5–70 minutes). At T0, 18 specimens had no growth of any organisms, 32 exhibited growth of only MSF, and 60 grew at least 1 potentially pathogenic organism alone or in combination with MSF or another pathogen. The following gram-negative organisms (total number of cultures with this organism) were recovered over the 48-hour study period: Escherichia coli (n = 32), Klebsiella pneumoniae (n = 15), Proteus mirabilis (n = 7), Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 2), Citrobacter freundii (n = 1), Klebsiella oxytoca (n = 1), Shigella species (n = 1), Raoultella ornithinolytica (n = 1), Gardnerella vaginalis (n = 1). In addition, 8 cultures were positive for yeast, including Candida albicans (n = 2), Candida parapsilosis (n = 2), Candida tropicalis (n = 2), and Candida species, not further specified (n = 2). Thirteen cultures were positive for Enterococcus species, and 10 cultures were positive for various gram-positive cocci, including Staphylococcus saprophyticus, other coagulase-negative staphylococci, group B streptococci, and viridans group streptococci. All organisms were identified using standard identification methods approved by the Clinical and Laboratory Standards Institute and the Food and Drug Administration, which are commonly used in clinical microbiology laboratories. The culture results by categorical analysis for all specimens over all time points are summarized in Table 1. Differences in the number of specimens with more than 10 CFU/mL pathogens (range, 33–36) between the refrigerated urine specimens and the BDU samples and between the time points T0 and T3 (24 h) were not statistically significant. Similarly, no statistically significant difference was seen in the number of cultures with more than or equal to 10 pathogens but less than 10 CFU/mL between T0 and T3 for the BDU and R-NPU samples. By contrast, the numbers of cultures having more than 10 CFU/mL pathogens in the nonpreservative urine specimen that was stored at room temperature (RT-NPU) changed significantly by 24 hours after collection with the number of specimens having more than 10 CFU/mL pathogens increasing from 35 to 70. During the same period (T0–T3), the number of specimens with 10 CFU/mL pathogens but less than 10 CFU/mL decreased from 10 to 4 for the RT-NPU storage condition. Extending the window of observation to a 48-hour period, the number of samples with pathogens at T0 (n = 60) increased to 81 in the RT-NPU group, 61 R-NPU samples, and 63 BDU samples. Although the changes for the R-NPU and BDU samples were not statistically significant, the changes for the RT-NPU samples were significant (P < .001) (Table 1).
Furthermore, we analyzed urine specimens that were negative for growth (n = 18) and/or showed MSF only (n = 32) at T0. These results are shown in Table 2 and Table 3. Again, a significant number of samples in the RT-NPU group changed from no-growth and/or MSF at T0 to presence of pathogens in various colony counts. However, changes in the R-NPU and BDU groups were not statistically significant.
Results for all cultures based on storage condition were further analyzed with regard to whether the culture result would be considered clinically significant, ie, leading to a complete organism identification and antimicrobial susceptibility testing Table 4. Culture results showing the presence of more than or equal to 10 CFU/mL of any potential uropathogen were considered clinically significant. Considering the results of all urine cultures and storage conditions at T0, clinically significant results were present in 45 specimens, whereas 65 specimens had no growth or had clinically insignificant growth or presence of MSF that would not have resulted in a complete urine culture workup. In this analysis, specimens stored at room temperature showed a significant change of culture results toward the presence of pathogens at any later point of culture (T1 – T4). These changes were statistically significant (P < .001). Minor trends observed for the other 2 specimen types (R-NPU and BDU) were not statistically significant.
Finally, the stability of culture results assessed as CFU (log10)/mL based on type of microorganism and type of storage condition over time for all urine specimens with significant numbers of a (potential) uropathogen at T0 were compared, as shown in Table 5. The mean value for the amount of organisms present in the BDU urine samples remained fairly constant over a 48-hour period, and the minor variation in CFU (log10)/mL were not statistically significant. Similarly, no statistically significant change was observed in the refrigerated (R-NPU) urine samples. In contrast, the amount of organisms, expressed as CFU (log10)/mL, identified in the RT-NPU samples increased significantly between T0 and T4 time points, and these changes were highly statistically significant (P < .001) for the gram-negative organisms (including E coli and K pneumoniae); less significant changes were observed for gram-positive organisms and yeast.
Results
A total of 110 urine specimens were included in this study. Seventy-four urine samples were obtained from female patients (67%) and 36 urine samples were from male patients (33%). Patients ranged in age from 17 to 95 years, with an average age of 57 years. The average time between the collection of the urine specimen and its arrival in the laboratory was 25 minutes (range, 5–70 minutes). At T0, 18 specimens had no growth of any organisms, 32 exhibited growth of only MSF, and 60 grew at least 1 potentially pathogenic organism alone or in combination with MSF or another pathogen. The following gram-negative organisms (total number of cultures with this organism) were recovered over the 48-hour study period: Escherichia coli (n = 32), Klebsiella pneumoniae (n = 15), Proteus mirabilis (n = 7), Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 2), Citrobacter freundii (n = 1), Klebsiella oxytoca (n = 1), Shigella species (n = 1), Raoultella ornithinolytica (n = 1), Gardnerella vaginalis (n = 1). In addition, 8 cultures were positive for yeast, including Candida albicans (n = 2), Candida parapsilosis (n = 2), Candida tropicalis (n = 2), and Candida species, not further specified (n = 2). Thirteen cultures were positive for Enterococcus species, and 10 cultures were positive for various gram-positive cocci, including Staphylococcus saprophyticus, other coagulase-negative staphylococci, group B streptococci, and viridans group streptococci. All organisms were identified using standard identification methods approved by the Clinical and Laboratory Standards Institute and the Food and Drug Administration, which are commonly used in clinical microbiology laboratories. The culture results by categorical analysis for all specimens over all time points are summarized in Table 1. Differences in the number of specimens with more than 10 CFU/mL pathogens (range, 33–36) between the refrigerated urine specimens and the BDU samples and between the time points T0 and T3 (24 h) were not statistically significant. Similarly, no statistically significant difference was seen in the number of cultures with more than or equal to 10 pathogens but less than 10 CFU/mL between T0 and T3 for the BDU and R-NPU samples. By contrast, the numbers of cultures having more than 10 CFU/mL pathogens in the nonpreservative urine specimen that was stored at room temperature (RT-NPU) changed significantly by 24 hours after collection with the number of specimens having more than 10 CFU/mL pathogens increasing from 35 to 70. During the same period (T0–T3), the number of specimens with 10 CFU/mL pathogens but less than 10 CFU/mL decreased from 10 to 4 for the RT-NPU storage condition. Extending the window of observation to a 48-hour period, the number of samples with pathogens at T0 (n = 60) increased to 81 in the RT-NPU group, 61 R-NPU samples, and 63 BDU samples. Although the changes for the R-NPU and BDU samples were not statistically significant, the changes for the RT-NPU samples were significant (P < .001) (Table 1).
Furthermore, we analyzed urine specimens that were negative for growth (n = 18) and/or showed MSF only (n = 32) at T0. These results are shown in Table 2 and Table 3. Again, a significant number of samples in the RT-NPU group changed from no-growth and/or MSF at T0 to presence of pathogens in various colony counts. However, changes in the R-NPU and BDU groups were not statistically significant.
Results for all cultures based on storage condition were further analyzed with regard to whether the culture result would be considered clinically significant, ie, leading to a complete organism identification and antimicrobial susceptibility testing Table 4. Culture results showing the presence of more than or equal to 10 CFU/mL of any potential uropathogen were considered clinically significant. Considering the results of all urine cultures and storage conditions at T0, clinically significant results were present in 45 specimens, whereas 65 specimens had no growth or had clinically insignificant growth or presence of MSF that would not have resulted in a complete urine culture workup. In this analysis, specimens stored at room temperature showed a significant change of culture results toward the presence of pathogens at any later point of culture (T1 – T4). These changes were statistically significant (P < .001). Minor trends observed for the other 2 specimen types (R-NPU and BDU) were not statistically significant.
Finally, the stability of culture results assessed as CFU (log10)/mL based on type of microorganism and type of storage condition over time for all urine specimens with significant numbers of a (potential) uropathogen at T0 were compared, as shown in Table 5. The mean value for the amount of organisms present in the BDU urine samples remained fairly constant over a 48-hour period, and the minor variation in CFU (log10)/mL were not statistically significant. Similarly, no statistically significant change was observed in the refrigerated (R-NPU) urine samples. In contrast, the amount of organisms, expressed as CFU (log10)/mL, identified in the RT-NPU samples increased significantly between T0 and T4 time points, and these changes were highly statistically significant (P < .001) for the gram-negative organisms (including E coli and K pneumoniae); less significant changes were observed for gram-positive organisms and yeast.
