肺炎衣原体在儿童急性下呼吸道感染中的情况

Invasive Chlamydia pneumoniae infections in children with acute lower respiratory tract infections

目的 探讨肺炎衣原体在急性下呼吸道感染 (ALRI)中的感染情况。方法 收集 1997年和 1998年两年冬、春季节、年龄在 3个月～ 14岁、起病在 1周以内、诊断为ALRI的 2 0 1例患儿的配对血清标本 ,其中 1997年 10 0例 ,1998年 10 1例 ,通过使用荧光免疫 (MIF)方法检测其肺炎衣原体抗体。结果 2 0 1例ALRI儿童中 ,急性肺炎衣原体感染 2 3例 ( 11 4%) ,既往感染 63例 ( 3 1 3 %)。在1997年检测的 10 0例中 ,急性感染 2 1例 ( 2 1 0 %) ,既往感染 3 3例 ( 3 3 0 %) ;1998年检测的 10 1例中 ,急性感染仅 2例 ( 2 0 %) ,既往感染 3 0例 ( 2 9 7%)。两年度比较 ,既往感染率接近 (P >0 0 5 ) ,而急性感染率差异有非常显著意义 ,1997年急性感染率随年龄的增长而上升 ,1998年未显示年龄间差异。结论 在ALRI患儿中 ,存在肺炎衣原体感染 ,1997年的感染率高于 1998年。

Objective Chlamydia pneumoniae mainly causes acute lower respiratory tract infections (ALRI), but there is no specific diagnosis in clinic at present. This study was to investigate invasive Chlamydia pneumoniae infections in children with ALRI. Methods The paired sera samples from 201 children aged 3 months to 14 years with ALRI seen in 1997 and 1998 were tested for Chlamydia pneumoniae IgM and IgG antibodies to K 6 antigen by means of a micro-immunofluorescence method. Of the 201 paired sera samples, 100 were collected in 1997 and 101 in 1998. We recorded the symptoms and signs, blood count, the result of chest X-rays and clinical treatment at the same time. Serum findings diagnostic for Chlamydia pneumoniae: A four-fold or greater rise in titer between paired sera in IgG, an IgG titer ≥1∶512, or an IgM titer ≥1∶16 was considered diagnostic of acute chlamydia pneumoniae infection; The pre-existing infection was defined as an IgG titer between >1∶16 and <1∶512. We classified the patients according to the ages, the disease severity and the clinical signs to analyze the results. Results Evidence of acute Chlamydia pneumoniae infection was found in 23 cases (11.4%) of the 201 children with ALRI, of which 21 cases (21.0%) were seen in 1997 and 2 cases (2.0%) in 1998, respectively. The number of acute Chlamydial pneumonia cases seen in 1997 was obviously higher than that in 1998 (P<0.01). Sixty-three cases had previous Chlamydial pneumonia, of whom 33 (33.0%) were seen in 1997 and 30 (29.7%) in 1998, respectively, which had no significant difference (P>0.05). Conclusion There were Chlamydia pneumoniae infections in children with ALRI, and prevalence of the infections in 1997 were much higher than in 1998.