First Department of Internal Medicine, Division of Respiratory Medicine, Infectious Disease and Allergology, Kansai Medical University, 2-3-1 Shin-machi, Hirakata, Osaka, 573-1191, Japan.
Respir Investig. 2022 Jan;60(1):56-67. doi: 10.1016/j.resinv.2021.09.009. Epub 2021 Nov 5.
Atypical pneumonia is caused by atypical pathogens that are not detectable with Gram stain and cannot be cultured using standard methods. The most common causative organisms of atypical pneumonia are Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species. The therapeutic approach for atypical pneumonias is different than that for typical pneumonia. Typical bacterial pathogens classically respond to β-lactam antimicrobial therapy because they have a cell wall amenable to β-lactam disruption. On the contrary, most atypical pathogens do not have a bacterial cell wall, some are intracellular (e.g., Legionella), and some are paracellular (e.g., M. pneumoniae). To prevent an increase in the number of antimicrobial-resistant strains, the Japanese pneumonia guidelines have proposed a differential diagnosis for typical bacterial pneumonia and atypical pneumonia to select an appropriate antibiotic for the management of mild-to-moderate pneumonia. The guidelines have set up six parameters and criteria based on the clinical symptoms, physical signs, and laboratory data. However, in the elderly individuals and patients with underlying diseases, the differential diagnosis may be difficult or a mixed infection may be latent. Therefore, in these individuals, the administration of a β-lactam drug plus a macrolide or tetracycline, or only fluoroquinolone should be considered from the beginning to cover bacterial and atypical pneumonia.
非典型肺炎是由非典型病原体引起的，这些病原体不能通过革兰氏染色检测，也不能用标准方法培养。引起非典型肺炎的最常见病原体是肺炎支原体、肺炎衣原体和军团菌属。非典型肺炎的治疗方法与典型肺炎不同。典型的细菌病原体通常对β-内酰胺类抗菌药物治疗有反应，因为它们的细胞壁容易受到β-内酰胺类药物的破坏。相反，大多数非典型病原体没有细菌细胞壁，有些是细胞内的（如军团菌），有些是细胞间的（如肺炎支原体）。为了防止抗菌药物耐药菌株的增加，日本肺炎指南提出了典型细菌性肺炎和非典型肺炎的鉴别诊断，以选择适当的抗生素来治疗轻度至中度肺炎。该指南基于临床症状、体征和实验室数据制定了六个参数和标准。然而，在老年人和患有基础疾病的患者中，鉴别诊断可能较为困难或存在混合感染。因此，对于这些患者，应从一开始就考虑使用β-内酰胺类药物加大环内酯类或四环素类药物，或仅使用氟喹诺酮类药物，以覆盖细菌和非典型肺炎。
