Jardine Luke, Davies Mark W, Faoagali Joan
Grantley Stable Neonatal Unit, Royal Brisbane and Women's Hospital, Brisbane, Qld, Australia.
J Paediatr Child Health. 2006 Dec;42(12):797-802. doi: 10.1111/j.1440-1754.2006.00980.x.
We aimed to determine the laboratory detection time of bacteraemia in neonatal blood cultures, and whether this differed by: organism; samples deemed to represent true bacteraemia versus contaminants; and blood cultures collected from an infant <48 h of age (early) or >or=48 h of age (late).
A retrospective audit of all positive blood cultures collected from neonates in the Grantley Stable Neonatal Unit, Royal Women's Hospital, Brisbane, between 1 January 2000 and 31 December 2004 was undertaken. The bacteraemia detection method used was the BacTAlert system with Peds bottles.
Two hundred and three positive blood cultures were included in the analysis. One hundred and sixteen (57%) were deemed septicaemia, 87 (43%) were deemed contaminants. The median (interquartile range) time to positivity for positive blood cultures deemed septicaemia and contaminants were 15.9 (11.6, 22.2) and 30.2 (20.4, 43.9) h, respectively. Fifty-six (28%) positive blood cultures were collected when infants were <48 h of age and 147 (72%) were collected in infants >or=48 h of age. Post hoc analysis revealed that the time to positivity for early septicaemia was 13.7 (11, 16.7) h; early contaminant was 25.2 (19.2, 33.8) h; late septicaemia was 17.2 (12.2, 23.4) h; and late contaminant was 37.9 (21.7, 51.2) h. The time to positivity for: Group B streptococcus was 9.3 (8.2, 11.0) h; Escherichia coli was 11.3 (10.0, 13.5) h; and coagulase-negative staphylococci was 28.9 (20.5, 41.2) h.
The incubation time for positive blood cultures significantly differs by organism type and whether they are considered early or late septicaemia versus contaminants. We recommend that: infants who are <48 h of age at the time of blood culture collection, who remain clinically well and have negative cultures 36 h after the initial collection can safely have their antibiotic treatment ceased; infants who are >or=48 h of age at the time of collection should continue antibiotic treatment for at least 48 h before cessation is considered.
我们旨在确定新生儿血培养中菌血症的实验室检测时间，以及该时间是否因以下因素而有所不同：微生物种类；被视为真正菌血症与污染物的样本；以及从年龄小于48小时（早期）或大于或等于48小时（晚期）的婴儿采集的血培养样本。
对2000年1月1日至2004年12月31日期间在布里斯班皇家妇女医院格兰特利·斯特布尔新生儿病房采集的所有新生儿阳性血培养样本进行回顾性审计。使用的菌血症检测方法是带有儿科瓶的BacTAlert系统。
203份阳性血培养样本纳入分析。其中116份（57%）被视为败血症，87份（43%）被视为污染物。被视为败血症和污染物的阳性血培养样本达到阳性的中位（四分位间距）时间分别为15.9（11.6，22.2）小时和30.2（20.4，43.9）小时。56份（28%）阳性血培养样本是在婴儿小于48小时时采集的，147份（72%）是在婴儿大于或等于48小时时采集的。事后分析显示，早期败血症达到阳性的时间为13.7（11，16.7）小时；早期污染物为25.2（19.2，33.8）小时；晚期败血症为17.2（12.2，23.4）小时；晚期污染物为37.9（21.7，51.2）小时。B组链球菌达到阳性的时间为9.3（8.2，11.0）小时；大肠杆菌为11.3（10.0，13.5）小时；凝固酶阴性葡萄球菌为28.9（20.5，41.2）小时。
阳性血培养样本的培养时间因微生物类型以及它们被视为早期或晚期败血症还是污染物而有显著差异。我们建议：血培养采集时年龄小于48小时、临床状况良好且初次采集后36小时培养结果为阴性的婴儿，可以安全地停止抗生素治疗；采集时年龄大于或等于48小时的婴儿，在考虑停止治疗前应继续抗生素治疗至少48小时。
