The prevalence and microbiology of concomitant respiratory bacterial infections in patients with SARS-CoV-2 infection are not yet fully understood. In this retrospective study, we assessed respiratory bacterial co-infections in lower respiratory tract samples taken from intensive care unit-hospitalized COVID-19 patients, by comparing the conventional culture approach to an innovative molecular diagnostic technology.

A total of 230 lower respiratory tract samples (i.e., bronchial aspirates or bronchoalveolar lavages) were taken from 178 critically ill COVID-19 patients. Each sample was processed by a semi-quantitative culture and by a multiplex PCR panel (FilmArray Pneumonia Plus panel), allowing rapid detection of a wide range of clinically relevant pathogens and a limited number of antimicrobial resistance markers.

More than 30% of samples showed a positive bacterial culture, with Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus the most detected pathogens.

FilmArray showed an overall sensitivity and specificity of 89.6% and 98.3%, respectively, with a negative predictive value of 99.7%. The molecular test significantly reduced the turn-around-time (TAT) and increased the rates of microbial detection. Most cases missed by culture were characterized by low bacterial loads (10⁴–10⁵ copies/mL). FilmArray missed a list of pathogens not included in the molecular panel, especially Stenotrophomonas maltophilia (8 cases).

FilmArray can be useful to detect bacterial pathogens in lower respiratory tract specimens of COVID-19 patients, with a significant decrease of TAT. The test is particularly useful to rule out bacterial co-infections and avoid the inappropriate prescription of antibiotics.

SARS-CoV-2 感染患者并发呼吸道细菌感染的患病率和微生物学尚未完全了解。在这项回顾性研究中，我们通过比较传统的培养方法与创新的分子诊断技术，评估了从重症监护病房住院的 COVID-19 患者中采集的下呼吸道样本中的呼吸道细菌合并感染。

从 178 名重症 COVID-19 患者身上采集了总共 230 份下呼吸道样本（即支气管抽吸物或支气管肺泡灌洗液）。每个样本都经过半定量培养和多重 PCR 面板（FilmArray Pneumonia Plus面板）处理，可以快速检测范围广泛的临床相关病原体和有限数量的抗菌素耐药性标记。

超过30%的样本细菌培养呈阳性，其中铜绿假单胞菌、肺炎克雷伯菌和金黄色葡萄球菌是检出最多的病原体。

FilmArray 的总体敏感性和特异性分别为 89.6% 和 98.3%，阴性预测值为 99.7%。分子测试显着缩短了周转时间 (TAT) 并提高了微生物检测率。大多数培养遗漏的病例的特点是细菌载量低（10 ⁴ –10 ⁵拷贝/mL）。FilmArray 遗漏了一份未包含在分子面板中的病原体列表，尤其是嗜麦芽窄食单胞菌（8 例）。

FilmArray 可用于检测 COVID-19 患者下呼吸道标本中的细菌病原体，TAT 显着降低。该测试对于排除细菌合并感染和避免抗生素处方不当特别有用。