Fine M J, Orloff J J, Rihs J D, Vickers R M, Kominos S, Kapoor W N, Arena V C, Yu V L
Department of Medicine, University of Pittsburgh, Pennsylvania.
J Gen Intern Med. 1991 May-Jun;6(3):189-98. doi: 10.1007/BF02598958.
To evaluate the preparation and interpretation of sputum Gram stains by housestaff physicians in the assessment of patients with community-acquired pneumonia.
A prospective, multicenter study.
Two university-affiliated hospitals in Pittsburgh.
Ninety-nine cases of clinically and radiographically established pneumonia occurring in 97 patients. Diagnostic test assessment: Housestaff and microbiology personnel prepared a Gram stain for each case of pneumonia. Housestaff assessed the presence and identity of a predominant microbial organism on the slides they prepared. Two senior staff microbiologists, blinded to patient and preparer, evaluated all slides for preparation, sputum purulence, and identification of the predominant organism. Two reference standards were used to assess the sensitivity, specificity, and predictive values of housestaff's Gram-stain interpretations: 1) senior staff microbiologists' determinations of the microbes present using the slides without benefit of culture results, and 2) the etiologic agent derived from results of sputum culture, blood culture, or serology.
Housestaff physicians completed a Gram stain in 58% of the pneumonia episodes. Gram stains were not made in 42% of cases, primarily because patients were unable to produce sputum. Fifteen percent of housestaff's smears were judged inadequately prepared, compared with 3% for the laboratory personnel (p less than 0.01). Housestaff obtained purulent sputum samples significantly more often than did nursing personnel (58% versus 38%; p less than 0.01). Housestaff's Gram stains were 90% sensitive for detecting pneumococcus, with a 50% false-positive rate. The sensitivity of the Gram stain was less for identification of Haemophilus influenzae than for identification of Streptococcus pneumoniae. A single antimicrobial agent was chosen as initial therapy for 50% of the patients in whom housestaff identified a predominant organism, compared with 30% in whom a predominant organism was not identified (p less than or equal to 0.05).
Although housestaff obtained purulent sputum samples more frequently than did nursing personnel, they made systematic errors in the preparation and interpretation of Gram-stained slides. Housestaff physicians should receive formal training in the preparation and interpretation of Gram stains; the specific defects elucidated in this study warrant special attention.
评估住院医师在社区获得性肺炎患者评估中制备和解读痰革兰氏染色的情况。
一项前瞻性多中心研究。
匹兹堡的两家大学附属医院。
97例患者中发生的99例临床和影像学确诊的肺炎病例。诊断测试评估：住院医师和微生物学人员为每例肺炎病例制备革兰氏染色。住院医师评估他们制备的载玻片上主要微生物的存在和种类。两名资深微生物学工作人员在对患者和制备者不知情的情况下，评估所有载玻片的制备情况、痰的脓性以及主要微生物的鉴定。使用两个参考标准来评估住院医师革兰氏染色解读的敏感性、特异性和预测价值：1）资深微生物学工作人员在不参考培养结果的情况下使用载玻片对存在的微生物进行的判定，以及2）源自痰培养、血培养或血清学结果的病原体。
住院医师在58%的肺炎发作中完成了革兰氏染色。42%的病例未进行革兰氏染色，主要原因是患者无法咳出痰液。住院医师制备的涂片中有15%被判定制备不充分，而实验室人员为3%（p<0.01）。住院医师获得脓性痰标本的频率明显高于护理人员（58%对38%；p<0.01）。住院医师的革兰氏染色检测肺炎球菌的敏感性为90%，假阳性率为50%。革兰氏染色鉴定流感嗜血杆菌的敏感性低于鉴定肺炎链球菌。在住院医师确定主要微生物的患者中，50%的患者选择单一抗菌药物作为初始治疗，而未确定主要微生物的患者中这一比例为30%（p≤0.05）。
尽管住院医师获得脓性痰标本的频率高于护理人员，但他们在革兰氏染色载玻片的制备和解读中存在系统性错误。住院医师应接受革兰氏染色制备和解读的正规培训；本研究中阐明的具体缺陷值得特别关注。
