Detection Of Pathogens From Patients With Community-Acquired Pneumonia

Objectives To investigate the categories and sensitive antibiotics for pathogens from patients with community-acquired pneumonia(CAP) and the variation of categories distribution with different seasons and age of patients in city Hefei, so as to orient clinical diagnosis and treatment. Multiple PCR system to detect three species of atypical pathogens includes Mycoplasma pneumoniae, Chlamydia pneumoniae and legionella pneumophila was designed at the same time. The difference of sensitivity and specificity of multiple PCR and serological detection was compared. Methods sputum and matters in bronchus were collected from patients with CAP that had not been treated in different seasons. Meanwhile, blood sample from patients within acute stage and convalescence stage were also collected. Parts of sputum were used to do bacteria and fungus culture and then pathogens resistance to frequently used antibiotics was tested. Another parts of sputum were used to detect Mycoplasma pneumoniae, Chlamydia pneumoniae and legionella pneumophila simultaneously by multiple PCR. Primers based on specific conservative sequence from Mycoplasma pneumoniae, Chlamydia pneumoniae and legionella pneumophila were designed. The difference of length of every amplified fragment had at least 100 bp from each other so as to distinguish them easily. DNA amplification were carried out to Standard strain of Mycoplasma pneumoniae, Chlamydia pneumoniae and legionella pneumophila, and analysis the amplified products. The conditions of temperature, the length of amplification and primer for multiple PCR were optimized. This was followed by the analysis of the sensitivity of multiple PCR. In order to analyze the specificity of multiple PCR, multiple PCR detection system was used to detect Blastomyces albicans, Chlamydiae trachomatis, Escherichia coli, hemophilies influenzae, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, Human cytomegalovirus, duovirus, adenovirus and Henrietta Lacks strain of cancer cells. After the multiple PCR system was optimized, the specificity and sensitivity of this detection system with serological detection were compared. Results Multiple infections such as bacteria and atypical pathogens intermixed infections were common in 154 patients with CAP in city Hefei. Streptococcus pneumoniae was the most common organisms among typical pathogens infection. Mycoplasma pneumoniae was frequently noted in atypical pathogens infection. Atypical pathogens are mostly found in the individuals from 8 to 14 years old. Typical pathogens infection cases in summer were less than other seasons. The sensitive antibiotics for pathogens were identified. The multiple PCR system to detect atypical pathogens was proved to be very efficient. The sensitivity of multiple PCR is 100copies/100μl. The specificity of this detection system was proved to be outstandingly good. Serological detection and DNA amplification were carried out simultaneously for each sample of 154 patients. Among 35 Mycoplasma pneumoniae infection cases, 15 cases were confirmed by DNA amplification only, 1 case was confirmed by serological detection only and 19 cases were confirmed by both of them. Among 11 legionella pneumophila infection cases, 3 cases were confirmed by DNA amplification only, 1 case was confirmed by serological detection only and 7 cases were confirmed by both of them. The multiple PCR detection system was proved to be very sensitive. Conclusions Multiple infections are common in 154 patients with CAP in city Hefei. Based on the test of drug resistance, the pathogens sensitive antibiotics should be used for treatment of CAP patients. Streptococcus pneumoniae is the most common organisms among typical pathogens infection. Mycoplasma pneumoniae is frequently noted in atypical pathogens infection. Atypical pathogens are mostly found in the individuals from 8 to 14 years old. The cases of typical pathogens infection in summer are less than other seasons. The multiple PCR system to detect atypical pathogens was proved to be very efficient. The sensitivity of multiple PCR is 100copies/100μl. The specificity and sensitivity of this detection system was proved to be satisfactory.