The objective of this study was to evaluate the performances of the automated digital imaging of Gram-stained slides against manual microscopy. Four hundred forty-three identified Gram-stained slides were included in this study. When both methods agreed, we considered the results as correct, and no further examination was carried out. Whenever the methods gave discrepant results, we reviewed the digital images and the glass slides by manual microscopy to avoid incorrectly read smears. The final result was a consensus of multiple independent reader interpretations. Among the 443 slides analyzed in this study, 101 (22.8%) showed discrepant results between the compared methods. The rates of discrepant results according to the specimen types were 5.7% (9/157) for positive blood cultures, 42% (60/142) for respiratory tract specimens, and 22% (32/144) for sterile site specimens. After a subsequent review of the discrepant slides, the final rate of discrepancies dropped to 7.0% (31/443). The overall agreement between the compared methods and the culture results reached 78% (345/443) and 79% (349/443) for manual microscopy and automated digital imaging, respectively. According to culture results, the specificity for automated digital imaging and manual microscopy were 90.8% and 87.7% respectively. In contrast, sensitivity was 84.1% for the two compared methods. The discrepant results were mostly encountered with microorganism morphologies of rare occurrence. The results reported in this study emphasize that on-screen reading is challenging, since the recognition of morphologies on-screen can appear different as compared to routine manual microscopy. Monitoring of Gram stain errors, which is facilitated by automated digital imaging, remains crucial for the quality control of reported Gram stain results.

本研究的目的是评估革兰氏染色载玻片的自动数字成像对手动显微镜的性能。本研究包括 443 张已鉴定的革兰染色载玻片。当两种方法一致时，我们认为结果是正确的，没有进行进一步的检查。每当这些方法给出不一致的结果时，我们都会通过手动显微镜检查数字图像和载玻片，以避免错误地读取涂片。最终结果是多个独立读者解释的共识。在本研究分析的 443 张载玻片中，101 张 (22.8%) 显示出比较方法之间的差异结果。根据样本类型，血培养阳性的结果差异率为 5.7% (9/157)，呼吸道标本为 42% (60/142)，无菌部位标本为 22% (32/144)。在对差异载玻片进行后续审查后，最终差异率降至 7.0% (31/443)。对于手动显微镜和自动数字成像，比较方法和培养结果之间的总体一致性分别达到 78% (345/443) 和 79% (349/443)。根据培养结果，自动数字成像和手动显微镜的特异性分别为 90.8% 和 87.7%。相比之下，两种比较方法的灵敏度为 84.1%。不一致的结果主要出现在罕见的微生物形态上。本研究报告的结果强调了屏幕阅读具有挑战性，因为与常规手动显微镜相比，屏幕上的形态识别可能看起来不同。