Clementsen Paul, Permin Henrik, Norn Svend
Department of Pulmonary Medicine, Gentofte University Hospital, Hellerup, Denmark.
J Investig Allergol Clin Immunol. 2002;12(2):73-9.
Chlamydia pneumoniae (CP) is a common cause of respiratory tract infections, and several studies have asked whether it may play a pathogenic role in connection with bronchial asthma and chronic obstructive pulmonary disease (COPD). Evidence that CP infection is associated with these diseases is a cardinal item. However, evaluation of CP infection is hampered by difficulties in obtaining agreement on the definition of a gold standard. In the literature, serology is based on different cutoff points of antibody titres, which complicates the definition of CP seropositive findings and the classification of acute infection, chronic and past infection. In connection with acute and chronic infection, it is important to demonstrate the presence of CP by culture or polymerase chain reaction (PCR) in the respiratory tract, especially in the lower airways. Often, the results of serology is not associated with the findings by culture or PCR testing, which may involve the risk of inconclusive evidence. Evaluation of a possible presence of CP by clinical improvement after treatment with antibiotics is difficult since uncontrolled studies have been used and other microorganisms are also affected by antibiotics. Furthermore, many patients improve without antibiotics, and improvement has also been observed in patients remaining culture positive after treatment with antibiotics. It should also be noted that the antiinflammatory effects of antibiotics may improve the clinical status of patients. Despite these obstacles, studies point to the possibility that in some patients acute CP infections may lead to acute exacerbations of bronchial asthma. Whether a persistent CP infection contributes to chronic asthma or severe COPD, or whether it incites the diseases in previously healthy individuals is a question for further studies. Whether a causal relationship exists between CP infection and obstructive pulmonary disease or whether these patients are more susceptible to CP infection is unknown. Nevertheless, a cooperative role of CP in the proinflammatory mechanisms involved in these diseases remains to be examined since cellular studies show that CP stimulates the production and expression of cytokines, chemokines and adhesion molecules, actions that may amplify and prolong the inflammation.
肺炎衣原体（CP）是呼吸道感染的常见病因，多项研究探讨了其在支气管哮喘和慢性阻塞性肺疾病（COPD）中是否可能发挥致病作用。CP感染与这些疾病相关的证据是一个关键问题。然而，由于难以就金标准的定义达成共识，CP感染的评估受到了阻碍。在文献中，血清学基于不同的抗体滴度截断点，这使得CP血清阳性结果的定义以及急性感染、慢性感染和既往感染的分类变得复杂。对于急性和慢性感染，通过培养或聚合酶链反应（PCR）在呼吸道，尤其是下呼吸道中证明CP的存在很重要。通常，血清学结果与培养或PCR检测结果不相关，这可能存在证据不确定的风险。通过抗生素治疗后临床症状改善来评估CP可能存在的情况很困难，因为使用的是无对照研究，而且其他微生物也会受到抗生素的影响。此外，许多患者在未使用抗生素的情况下病情也会改善，并且在抗生素治疗后仍培养阳性的患者中也观察到了病情改善。还应注意的是，抗生素的抗炎作用可能会改善患者的临床状况。尽管存在这些障碍，但研究指出在一些患者中急性CP感染可能导致支气管哮喘急性加重的可能性。持续性CP感染是否导致慢性哮喘或严重COPD，或者它是否在先前健康的个体中引发这些疾病，是有待进一步研究的问题。CP感染与阻塞性肺疾病之间是否存在因果关系，或者这些患者是否更容易感染CP尚不清楚。然而，由于细胞研究表明CP刺激细胞因子､趋化因子和黏附分子的产生和表达，这些作用可能会放大和延长炎症，因此CP在这些疾病所涉及的促炎机制中的协同作用仍有待研究。
