Data on causative pathogens were available from a few studies only and highlighted the importance of Gram-negative rods, particularly in surgical site infection and ventilator-associated pneumonia.

仅有几项研究提供了有关病原体数据并且强调了革兰氏阴性杆菌的重要性，特别是在手术部位感染和呼吸机相关肺炎研究中提供了上述数据。

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Mycoplasma that lack a true cell wall, are gram-negative, and need sterols such as cholesterol for growth. In human beings, one species is a primary cause of nonbacterial pneumonia.

支原体属支原体属大量寄生的、致病的微生物，它们没有真正的细胞壁，呈格兰氏阴性并且生长时需要类固醇（比如胆固醇）。

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There is particular concern about Gram-negative bacteria (like E.coli and K. pneumonia), due to their outer membrane which can prevent some antibiotics from penetrating the cell.

BBC: Action on antibiotics