García-Vázquez Elisa, Marcos María Angeles, Mensa José, de Roux Andrés, Puig Jordi, Font Carmen, Francisco Gloria, Torres Antonio
Department of Infectious Diseases, Hospital Clínic, Barcelona, Spain.
Arch Intern Med. 2004 Sep 13;164(16):1807-11. doi: 10.1001/archinte.164.16.1807.
The usefulness of sputum culture in guiding microbiological diagnosis of community-acquired pneumonia is controversial. We evaluate and assess it using the Patients Outcome Research Team (PORT) predictive scoring system.
A cohort of 1669 patients with community-acquired pneumonia was studied. Before administering antibiotic therapy, sputum was collected and its quality evaluated. Samples were gram stained and those of good quality were assessed for a predominant morphotype (PM). Sputum cultures were processed according to standard protocols.
A sputum sample was obtained from 983 (59%) of the 1669 patients and 532 (54%) of the samples were of good quality. There was a PM in 240 (45%) of the latter samples (ie, for 14.4% of the 1669 patients) and there was no PM in 292 (55%). Culture yielded a microorganism in 207 (86%) of the 240 samples with PM and 57 (19.5%) of the 292 samples without PM (P<.05). Rates of sputum obtained, good-quality sputum specimens, PM identification, and positive culture were not significantly different among the PORT-score groups of patients (P>.05). The sensitivity and specificity of the gram-positive diplococci identification in the sputum culture of Streptococcus pneumoniae were 60% and 97.6%, and the positive and negative predictive values were 91% and 85.3%, respectively.
Good-quality sputum with PM could be obtained in only 14.4% of all patients. A PORT-score group in which sputum could be of greater usefulness in identifying the causative organism could not be identified. The presence of gram-positive diplococci in gram-stained sputum culture was highly specific for S pneumoniae.
痰培养在指导社区获得性肺炎的微生物学诊断中的作用存在争议。我们使用患者预后研究团队（PORT）预测评分系统对其进行评估。
对1669例社区获得性肺炎患者进行队列研究。在给予抗生素治疗前，收集痰液并评估其质量。样本进行革兰氏染色，质量良好的样本评估其优势形态类型（PM）。痰培养按照标准方案进行。
1669例患者中的983例（59%）获得了痰样本，其中532例（54%）样本质量良好。后一组样本中有240例（45%）存在PM（即占1669例患者的14.4%），292例（55%）不存在PM。在有PM的240例样本中，207例（86%）培养出微生物，在无PM的292例样本中，57例（19.5%）培养出微生物（P<0.05）。患者PORT评分组之间的痰液获取率、高质量痰标本率、PM识别率和阳性培养率无显著差异（P>0.05）。肺炎链球菌痰培养中革兰氏阳性双球菌识别的敏感性和特异性分别为60%和97.6%，阳性预测值和阴性预测值分别为91%和85.3%。
所有患者中只有14.4%能获得有PM的高质量痰液。未发现PORT评分组中痰液在识别致病微生物方面可能更有用的情况。革兰氏染色痰培养中革兰氏阳性双球菌的存在对肺炎链球菌具有高度特异性。
