PDF(Pubmed)
Abstract：
BACKGROUND: Recovering pathogenic bacteria and yeast from pediatric blood cultures and reliably distinguishing between pathogens and contaminants are likely to be improved by increasing the volume of blood submitted to microbiology laboratories for culturing beyond the low volumes that have historically have been used. The primary aim of this study was to assess whether the pathogen recovery rate would increase after implementation of a weight-based algorithm for determining the intended volume of blood submitted for culturing. Secondary aims were to: 1) evaluate the effects of the algorithm implementation on the blood culture contamination rate; 2) determine whether pathogens might be found more often than contaminants in several as opposed to single bottles when more than one bottle is submitted; and 3) describe the microbiological findings for pathogens and contaminants in blood cultures by applying a clinical validation of true blood culture positivity.
METHODS: A pre-post comparison of positivity and contamination rates after increasing the theoretical blood volume and number of blood culture bottles was performed, on the basis of a clinical validation of blood culture findings as pathogens vs contaminants.
RESULTS: We examined 5327 blood cultures, including 186 with growth (123 true positives and 63 contaminated). The rate of true positive blood cultures significantly increased from 1.6% (42/2553) pre to 2.9% (81/2774, p = .002) post intervention. The rate of contaminated blood cultures did not change significantly during the study period (1.4% [35/2553] pre vs 1.0% [28/2774], p = .222) post intervention), but the proportion of contaminated cultures among all positive cultures decreased from 45% (35/77) pre to 26% (28/109, p = .005) post intervention. A microorganism that grew in a single bottle was considered a contaminant in 35% (8/23) of cases, whereas a microorganism that grew in at least two bottles was considered a contaminant in 2% (1/49, p < .001) of cases. According to common classification criteria relying primarily on the identity of the microorganism, 14% (17/123) of the recovered pathogens would otherwise have been classified as contaminants.
CONCLUSIONS: Implementation of a weight-based algorithm to determine the volume and number of blood cultures in pediatric patients is associated with an increase in the pathogen recovery rate.
METHODS: A pre-post comparison of positivity and contamination rates after increasing the theoretical blood volume and number of blood culture bottles was performed, on the basis of a clinical validation of blood culture findings as pathogens vs contaminants.
RESULTS: We examined 5327 blood cultures, including 186 with growth (123 true positives and 63 contaminated). The rate of true positive blood cultures significantly increased from 1.6% (42/2553) pre to 2.9% (81/2774, p = .002) post intervention. The rate of contaminated blood cultures did not change significantly during the study period (1.4% [35/2553] pre vs 1.0% [28/2774], p = .222) post intervention), but the proportion of contaminated cultures among all positive cultures decreased from 45% (35/77) pre to 26% (28/109, p = .005) post intervention. A microorganism that grew in a single bottle was considered a contaminant in 35% (8/23) of cases, whereas a microorganism that grew in at least two bottles was considered a contaminant in 2% (1/49, p < .001) of cases. According to common classification criteria relying primarily on the identity of the microorganism, 14% (17/123) of the recovered pathogens would otherwise have been classified as contaminants.
CONCLUSIONS: Implementation of a weight-based algorithm to determine the volume and number of blood cultures in pediatric patients is associated with an increase in the pathogen recovery rate.
摘要：
背景:从儿科血液培养物中回收致病菌和酵母以及可靠地区分病原体和污染物可能通过增加提交给微生物实验室用于培养的血液的体积而超过历史上已经使用的低体积而得到改善。这项研究的主要目的是评估在实施基于重量的算法以确定用于培养的预期血液体积后，病原体回收率是否会增加。次要目的是：1）评估算法实施对血液培养污染率的影响；2）当提交多个瓶子时，确定是否可能比单个瓶子中的污染物更频繁地发现病原体；3）通过对真实的血液培养阳性进行临床验证，描述血液培养中病原体和污染物的微生物发现。
方法：在增加理论血容量和血培养瓶数量后，对阳性率和污染率进行了前后比较，基于对血液培养结果作为病原体和污染物的临床验证。
结果：我们检查了5327个血培养，包括186个增长(123个真阳性和63个污染)。真阳性血培养率从干预前的1.6％（42/2553）显着增加到干预后的2.9％（81/2774，p=.002）。在研究期间，血液培养物的污染率没有显著变化（1.4%[35/2553]前对1.0%[28/2774]，p=.222)干预后)，但是，在所有阳性培养物中，受污染培养物的比例从干预前的45％（35/77）下降到干预后的26％（28/109，p=0.005）。在35％（8/23）的病例中，在单个瓶子中生长的微生物被认为是污染物，而在2％（1/49，p<.001）的病例中，至少在两个瓶子中生长的微生物被认为是污染物。根据主要依靠微生物身份的常见分类标准，否则，14%(17/123)的回收病原体将被归类为污染物。
结论：实施基于体重的算法以确定儿科患者的血培养量和数量与病原体恢复率的增加有关。
方法：在增加理论血容量和血培养瓶数量后，对阳性率和污染率进行了前后比较，基于对血液培养结果作为病原体和污染物的临床验证。
结果：我们检查了5327个血培养，包括186个增长(123个真阳性和63个污染)。真阳性血培养率从干预前的1.6％（42/2553）显着增加到干预后的2.9％（81/2774，p=.002）。在研究期间，血液培养物的污染率没有显著变化（1.4%[35/2553]前对1.0%[28/2774]，p=.222)干预后)，但是，在所有阳性培养物中，受污染培养物的比例从干预前的45％（35/77）下降到干预后的26％（28/109，p=0.005）。在35％（8/23）的病例中，在单个瓶子中生长的微生物被认为是污染物，而在2％（1/49，p<.001）的病例中，至少在两个瓶子中生长的微生物被认为是污染物。根据主要依靠微生物身份的常见分类标准，否则，14%(17/123)的回收病原体将被归类为污染物。
结论：实施基于体重的算法以确定儿科患者的血培养量和数量与病原体恢复率的增加有关。
