Schermer Carol R, Sanchez Damion P, Qualls Clifford R, Demarest Gerald B, Albrecht Roxie M, Fry Donald E
Department of Surgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA.
J Trauma. 2002 Mar;52(3):463-8. doi: 10.1097/00005373-200203000-00008.
Febrile trauma patients have repeated blood cultures drawn during a prolonged hospitalization. We examined the diagnostic yield of blood cultures in severely injured patients to determine whether concurrent antimicrobial therapy or prophylactic administration of antibiotics affects blood culture growth. We also determined how rapidly growth changed to determine whether total numbers of blood cultures could be decreased. The hypotheses of the study were that concurrent antimicrobial administration affects blood culture yield, prophylactic administration alters the culture result, and repetitive culturing is unnecessary.
A retrospective chart review of trauma patients with minimum Injury Severity Score of 15 and minimum 5-day intensive care unit length of stay was performed. The dates and results of blood cultures and antibiotic type and administration dates were recorded. "Prophylactic" antibiotics were defined as antibiotics administered on admission to the unit. Computer software was used to match the blood culture date to the period of antimicrobial administration. Categorical data were compared using Fisher's exact test.
Two hundred fifty-eight patients met entry criteria, and 208 charts were complete for review. One hundred twenty-nine patients had 347 sets of blood cultures drawn. The positive blood culture rate was 10.8% in patients off antibiotics, and 13.9% in patients on antibiotics (p = 0.68). All prophylactic antibiotics included a beta-lactam. Only 18% of positive blood cultures in patients receiving prophylactic antibiotics were sensitive to beta-lactams as opposed to 59% sensitivity in those who did not receive prophylaxis (p = 0.03). One hundred seventy-six sets of blood cultures were performed after an initial positive culture. Only three patients with an initial positive culture had a second positive culture with a different organism. The mean time to culturing a new organism after initial growth was 19 days.
Concurrent antimicrobial administration does not alter blood culture yield. Prophylactic administration alters the type of organism cultured. Little new information is gained from repetitive culturing.
发热创伤患者在长期住院期间需多次进行血培养。我们研究了严重受伤患者血培养的诊断价值，以确定同时进行的抗菌治疗或预防性使用抗生素是否会影响血培养结果。我们还确定了培养结果变化的速度，以判断是否可以减少血培养的总数。本研究的假设是，同时使用抗菌药物会影响血培养结果，预防性用药会改变培养结果，且重复培养没有必要。
对创伤患者进行回顾性病历审查，这些患者的损伤严重程度评分至少为15分，在重症监护病房的住院时间至少为5天。记录血培养的日期和结果以及抗生素类型和用药日期。“预防性”抗生素定义为入院时使用的抗生素。使用计算机软件将血培养日期与抗菌药物使用时间段进行匹配。分类数据采用Fisher精确检验进行比较。
258例患者符合纳入标准，208份病历可供完整审查。129例患者共进行了347次血培养。未使用抗生素患者的血培养阳性率为10.8%，使用抗生素患者的阳性率为13.9%（p = 0.68）。所有预防性抗生素均为β-内酰胺类。接受预防性抗生素治疗的患者中，只有18%的血培养阳性结果对β-内酰胺类敏感，而未接受预防性治疗的患者中这一比例为59%（p = 0.03）。在初次血培养阳性后又进行了176次血培养。只有3例初次血培养阳性的患者第二次培养出不同的阳性菌株。初次培养出阳性菌株后，培养出新菌株的平均时间为19天。
同时进行抗菌治疗不会改变血培养结果。预防性用药会改变培养出的菌株类型。重复培养几乎无法获得新的信息。
