McGowan K L, Foster J A, Coffin S E
Division of Immunologic and Infectious Diseases, Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Pediatrics. 2000 Aug;106(2 Pt 1):251-5. doi: 10.1542/peds.106.2.251.
Using a continuously monitoring blood culture system, we determined the time to positivity of blood cultures performed on immunocompetent infants and children who were not receiving antibiotics at the time of culture.
This study was conducted prospectively using blood cultures taken in the emergency department and outpatient clinics of an urban pediatric teaching hospital from February 1, 1993, through December 31, 1996. Cultures were excluded if obtained from patients receiving antibiotics, patients with a central line, patients with prosthetic devices, or those being followed by the oncology division. Our measures included: 1) recording the time to positive culture obtained by using a continuously monitoring blood culture instrument, 2) patient information derived from the hospital computer system concerning antibiotic use and the presence of indwelling central venous catheters and prosthetic devices, and 3) a chart review of 10% of patients from whom positive cultures were obtained.
During the 47-month study period, 10 200 single bottle blood cultures were obtained, 711 (6.97%) of which became positive. Patients ranged in age from <1 week to 24 years (mean: 2.00 years). Two hundred fifty-eight cultures (36.3%) contained only pathogens, 370 (52%) contained only skin contaminants, and 83 (11.7%) contained a mixture of contaminant and pathogen. Of the 258 cultures containing only pathogens, 14% were positive by 12 hours, 87% by 24 hours, 92% by 36 hours, 95% by 48 hours, 98% by 60 hours, and 99.7% by 72 hours. Ninety-five percent of critical pediatric pathogens including Streptococcus pneumoniae, Salmonella and other Enterobacteriaceae, Neisseria meningitidis, and groups A and B streptococci were detected in <24 hours.
Because 87% of all cultures containing pathogens were detected within the first 24 hours of incubation, this study can assist emergency department, clinic, and primary care clinicians when making critical decisions concerning patients on whom blood cultures were obtained. Data on time to positivity of blood cultures can be used in conjunction with clinical status to support clinicians in making patient management decisions. Use of short stay (</=24 hours) or extended care units requiring less patient supervision may be easier to justify when a continuously monitoring blood culture instrument is used in the microbiology laboratory.bacteremia, sepsis.
使用连续监测血培养系统，我们确定了对免疫功能正常、培养时未接受抗生素治疗的婴幼儿和儿童进行血培养至阳性的时间。
本研究前瞻性地采用了1993年2月1日至1996年12月31日期间在一家城市儿科教学医院急诊科和门诊采集的血培养样本。如果样本来自接受抗生素治疗的患者、有中心静脉导管的患者、有假体装置的患者或肿瘤科室随访的患者，则将其排除。我们的测量指标包括：1）记录使用连续监测血培养仪器获得阳性培养结果的时间；2）从医院计算机系统获取的有关抗生素使用情况以及留置中心静脉导管和假体装置情况的患者信息；3）对10%血培养结果为阳性的患者进行病历回顾。
在47个月的研究期间，共获得10200份单瓶血培养样本，其中711份（6.97%）呈阳性。患者年龄范围从小于1周至24岁（平均：2.00岁）。258份培养物（36.3%）仅含有病原体，370份（52%）仅含有皮肤污染物，83份（11.7%）含有污染物和病原体的混合物。在仅含有病原体的258份培养物中，14%在12小时内呈阳性，87%在24小时内呈阳性，92%在36小时内呈阳性，95%在48小时内呈阳性，98%在60小时内呈阳性，99.7%在72小时内呈阳性。包括肺炎链球菌、沙门氏菌和其他肠杆菌科细菌、脑膜炎奈瑟菌以及A组和B组链球菌在内的95%的关键儿科病原体在24小时内被检测到。
由于87%含有病原体的培养物在培养的前24小时内被检测到，本研究可为急诊科、诊所和初级保健临床医生在对进行血培养的患者做出关键决策时提供帮助。血培养至阳性的时间数据可与临床状况结合使用，以支持临床医生做出患者管理决策。当微生物实验室使用连续监测血培养仪器时，使用短停留（≤24小时）或需要较少患者监督的延长护理单元可能更容易证明其合理性。菌血症，败血症。
