Clinic Research On Community Acquired Pneumonia Caused By Atypical Pathogens

Objectives:The aim of the study was to improve the potentia of diagnosis and therapy by investigating the etiological distribution and the clinical features of community acquired pneumonia (CAP) caused by the atypical pathogens.Methods:A study was performed on consecutive adult patients with CAP referred to the second affiliated hospital of Nanchang University over a 3-year period from 2004 to 2006,and the clinic data was collected. Pathogens of respiratory tract sputum and blood specimen were detected by bacterial culture and indirect immunofluorescence method. The etiological distribution of CAP was analyzed, then, 31 patients with Mycoplasma pneumoniae or Chlamydia pneumoniae infection were assigned to the observation group, and other 46 patients with bacteria infection were assigned to the control group. A retrospective analysis of clinical manifestation, auxiliary examination, therapy and prognosis of the two groups was made.Results:113 patients were enrolled and pathogens were identified in 64(56.6%) patients. The distribution of causal agents was as follows: Mycoplasma pneumoniae 24(21.2%), Streptococcus pneumoniae 14(12.4%), Hemophilus influenza 9(8%), Chlamydia pneumoniae 7 ( 6.2% ) ,Escherichia coli 2 ( 1.8% ) ,Legionella pneumoniae 1(0.8%), Moraxelle catarrhalis 1(0.8%), mixed infection of atypical pathogens with bacteria was found in 6 cases(5.3%). Compared with the control group, Dry cough, expectoration, white phlegm, chest distress and polypnea were the most common presenting symptoms in the observation group. Peripheral leucocyte and neutrophil count was normal in mostly patients of the observation group.The majority chest images of patients of the observation group display patching shadow. The chest images show that there was more lung marking thickened and focus of infection of multipl lobi in the observation group. In the observation group, 20 patients out of 31 had been treated by beta-lactam for 4.5±1.6 days before hospital admission, but the patients'body temperature didn't descend and their symptoms didn't relieved. After admission all of the patients had been treated by Azithromycin for 7～14 days, then 31 patients'body temperature descended to normal temperature within 3±1 days and their shadow of chest images disappeared after 2～4 weeks. In the control group, the patients had been treated by Cefuroxime sodium or Levofloxacin for 7～14 days after admission. The patients'body temperature descended to normal temperature within 2.7±1 days, and their shadow of chest images disappeared after 2～4 weeks.Conclusions:The findings suggest that the atypical pathogens, including Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumoniae, are the most common pathogens of CAP. The results suggest that dry cough, expectoration, white phlegm, chest distress and polypnea are the most common presenting symptoms in patients with CAP caused by atypical pathogens. Peripheral leukocyte and neutrophil count was normal in mostly patients with Mycoplasma pneumoniae or Chlamydia pneumoniae infection. The majority chest images of patients with atypical pathogens infection display patching shadow in single side or both sides, lung marking thickened, focus of infection of multipl lobus. Blood specimen of the cases with features mentioned above should be detected by indirect immuno- fluorescence method in order to identify the diagnosis. The results show that macrolides antibiotics or quinolones drugs should be used as preferred drug in CAP.