Riaz Omer J, Malhotra Ajai K, Aboutanos Michel B, Duane Therese M, Goldberg Aaron E, Borchers C Todd, Martin Nancy R, Ivatury Rao R
Department of Surgery, Division of Trauma/Critical Care/Emergency General Surgery, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, USA.
Am Surg. 2011 Mar;77(3):297-303.
Quantitative bronchoalveolar lavage (BAL) is used to diagnose ventilator-associated pneumonia (VAP). We prospectively compared semiquantitative (SQ) and quantitative (Qu) culture of BAL for VAP diagnosis. Ventilated patients suspected of VAP underwent bronchoscopic BAL. BAL fluid was examined by both Qu (colony-forming units [CFUs]/mL) and SQ culture (none, sparse, moderate, or heavy) and results were compared. VAP was defined as 10⁵ CFU/mL or greater on Qu culture. Over 36 months, 319 BALs were performed. Sixty-three of 319 (20%) showed diagnostic growth by Qu culture identifying a total of 81 organisms causing VAP. All 63 specimens showed growth of some organism(s) on SQ culture with 79 of 81 causative organisms identified and two (Pseudomonas, one; Corynebacterium, one) not identified. The remaining 256 specimens did not meet the threshold for VAP by the Qu method. Among these, 79 did not show any growth on SQ culture. Among the 240 specimens showing some growth on SQ culture, a total of 384 organisms were identified. VAP rates in relation to strength of growth on SQ culture were: sparse, 10 of 140 (7%); moderate, 24 of 147 (16%); and heavy, 45 of 97 (46%). Sensitivity (Sn), specificity (Sp), positive (PPV), and negative (NPV) predictive values of SQ culture of BAL fluid for the diagnosis of VAP were 97, 21, 21, and 97 per cent, respectively. Nonquantitative culture of BAL fluid is fairly accurate in ruling out VAP (high Sn and NPV). It however has poor Sp and PPV and using this method will lead to unnecessary antimicrobial use with its attendant complications of toxicity, cost, and resistance.
定量支气管肺泡灌洗（BAL）用于诊断呼吸机相关性肺炎（VAP）。我们前瞻性地比较了用于VAP诊断的BAL半定量（SQ）培养和定量（Qu）培养。怀疑患有VAP的通气患者接受支气管镜BAL检查。通过Qu（菌落形成单位[CFU]/mL）和SQ培养（无、稀少、中等或大量）对BAL液进行检查，并比较结果。VAP定义为Qu培养中菌落数≥10⁵CFU/mL。在36个月的时间里，共进行了319次BAL检查。319例中有63例（20%）通过Qu培养显示有诊断性生长，共鉴定出81种导致VAP的病原体。所有63份标本在SQ培养中均显示有某种病原体生长，81种致病病原体中有79种被鉴定出来，2种（假单胞菌1种；棒状杆菌1种）未被鉴定出来。其余256份标本未达到Qu方法诊断VAP的阈值。其中，79份在SQ培养中未显示任何生长。在240份在SQ培养中显示有某种生长的标本中，共鉴定出384种病原体。与SQ培养生长强度相关的VAP发生率分别为：稀少，140例中的10例（7%）；中等，147例中的24例（16%）；大量，97例中的45例（46%）。BAL液的SQ培养对VAP诊断的敏感性（Sn）、特异性（Sp）、阳性预测值（PPV）和阴性预测值（NPV）分别为97%、21%、21%和97%。BAL液的非定量培养在排除VAP方面相当准确（高Sn和NPV）。然而，其Sp和PPV较低，使用这种方法将导致不必要的抗菌药物使用及其伴随的毒性、成本和耐药性并发症。
