Hoffman A M, Viel L, Muckle C A, Tesarowski D B
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Ontario.
Can J Vet Res. 1991 Oct;55(4):325-31.
A novel method to reduce contamination of the bronchoscope during microbial sampling of the lower airways of foals was evaluated. Methylene blue (MB) was used as a nasopharyngeal dye marker to assess the relative contamination from the upper airways of bronchoalveolar lavage (BAL) specimens obtained by standard bronchoscopy (SB) and a "guarded" bronchoscopic method (GB). For GB, a clear sterile cellulose sheath was fitted over the bronchoscope in an effort to protect the endoscope tip and channel from contamination. Methylene blue was detected visually in seven of eight BAL samples from foals following SB, but in none of the samples recovered by GB (p less than 0.001). Significantly less MB was detected in BAL by spectrophotometry in the GB group as well (p less than 0.02). The GB was next employed to study the microbial flora in the lower airways of healthy weaned foals (n = 30). Bacteria were isolated from 29 of 30 (97%) BAL samples, and in moderate or large numbers from 26 of 30 (87%) of the foals. Potential pathogens, including Bordetella bronchiseptica, Streptococcus zooepidemicus, Staphylococcus aureus, Mycoplasma felis and Streptococcus pneumoniae, were cultured from the lower airways of foals. In conclusion, the bronchoscope and bronchoalveolar lavage specimens were readily contaminated by a dye marker placed in the nasopharynx of foals, and the degree of contamination was significantly reduced by sheathing the endoscope. This contamination during bronchoscopy may obscure the interpretation of isolates from BAL specimens from foals, which may possess a bacterial flora in the lower airways without cytological evidence of inflammation.
对一种减少马驹下呼吸道微生物采样期间支气管镜污染的新方法进行了评估。亚甲蓝（MB）用作鼻咽染料标记物，以评估通过标准支气管镜检查（SB）和“防护”支气管镜检查方法（GB）获得的支气管肺泡灌洗（BAL）标本来自上呼吸道的相对污染情况。对于GB方法，在支气管镜上安装一个透明无菌纤维素鞘，以保护内镜尖端和通道免受污染。在SB检查后的八匹小马驹的BAL样本中，有七个样本通过肉眼检测到了亚甲蓝，但在GB方法采集的样本中均未检测到（p<0.001）。通过分光光度法在GB组的BAL样本中检测到的MB也明显较少（p<0.02）。接下来使用GB方法研究健康断奶马驹（n=30）下呼吸道的微生物群。从30个BAL样本中的29个（97%）分离出细菌，并且在30匹小马驹中的26匹（87%）的样本中分离出的细菌数量为中等或大量。从小马驹的下呼吸道培养出了潜在病原体，包括支气管败血博德特氏菌、马链球菌兽疫亚种、金黄色葡萄球菌、猫支原体和肺炎链球菌。总之，放置在马驹鼻咽部的染料标记物很容易污染支气管镜和支气管肺泡灌洗标本，通过给内镜加鞘可显著降低污染程度。支气管镜检查期间的这种污染可能会模糊对来自马驹BAL标本分离株的解读，这些标本在下呼吸道可能存在细菌菌群，但没有炎症的细胞学证据。
