Investigation Of Etiology In The Hospitalized Patients With COPD During Acute Exacerbation

Objective:COPD is a preventable and treatable disease characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases. COPD mostly implicates lung, and adversely effects on all over the body(or extrapulmonary)sometimes. Epidemiologic survey has showed that the morbidity rate of COPD was surprisingly high, 8.2% in the population Aged 40 and Older. An exacerbation of COPD is an event in the natural course of the disease characterized by a change in the patient's baseline dyspnoea, cough and/or sputum beyond day-to-day variability sufficient to warrant a change in management. Many studies have indicated that infection was an important trigger for AECOPD. Because of limited condition, only serology and culture technology have been used for the most of etiological investigations in our country. Few of investigations utilized PCR detection technology. Our present study would detect several pathogens in respiratory tract of hospitalized patients suffered AECOPD, especially the distribution of respiratory-tract-related virus, and explore the influence of virus infection on patients'recovery time and inflammatory factors of hospital patients with AECOPD, in order to avoid unnecessary antibiotic application on clinic and provide theoretical proof for augmenting prevention and treatment of virus.Methods: Collecting sputum samples, which was frozen in -70℃refrigerator, of 106 hospitalized patients with AECOPD within 3 days admission from respiratory departments of ten Grade 3A hospitals and one Grade 2A hospital from Nov,2008 to Mar,2009. Meanwhile, recording patients'clinical data, such as basic information, history prior to admission (vaccine inoculation, medication, smoking, home oxygen therapy and so on),signs and symptoms during this exacerbation, auxiliary examination in hospital (imaging data, pathogen data, blood routine test, hepatic function, renal function, blood gas analysis) and treatment plan. The DNA and RNA in 106 qualified sputum samples was extracted by TIANamp Virus DNA/RNA Kits, followed by cDNA synthesis using reverse transcription technology .And then,the specific gene fragment of microorganisms in DNA and cDNA would be amplified by Bacteria polymerase chain reaction (PCR) kits and virus PCR kits. The concentration of interleukin-6(IL-6) and tumor necrosis factor alpha(TNF-α) in sputum samples was measured by Enzyme-linked Immunosorbent Assay(ELISA)kits.Results:1 Patients clinical data 10 unqualified sputum samples, tested by sputum smear, were removed from 116 patients'sputum samples. In the rest of 106 patients, with the characters as followings: 69.3% male, age (70.67±10.13),body mass index (24.08±6.71kg/m2),FEV1(1.29±0.53L),FEV1/FVC(55.18±10.19%),hospitalized for AECOPD in the past three years 83 patients (78.30%),nonsmoking history 42 patients(39.62%), quitting smoking 63 patients(59.43%),influenza vaccine inoculation 40 patients (37.73%),home oxygen therapy 2 patients(1.88%),long term hormone application 5 patients (4.72%),only suffered by AECOPD 29 patients(27.36%),inflammatory exudation in X-ray film or CT film 51 patients(48.11%),complicating with asthma 7 patients(6.60%),Type 2 Diabetes 20 patients(18.87%),Coronary Atherosclerotic Heart Disease 30 patients(28.30%),hypertension 42 patients(39.62%), pulmonary embolism 3 patients (2.83%),chronic pulmonary heart disease 33 patients(31.13%),other diseases 17 patients(16.04%).2 Pathogen PCR results 40 samples (37.70%) were positive for at least one viral pathogen, including influenza A virus 17 samples (16.04%), rhinoviruses 11 samples (10.38%),respiratory syncytial virus B 2 samples (1.89%),coronavirus229E/NL63 2 samples (1.89%), metapneumovirus 1 sample(0.94%),adenovirus 1 sample (0.94%),parainfluenza3 virus 1 sample (0.94%),mixed infection 5 samples (4.72%).Mixed infection included influenza A virus and adenovirus 2 samples (1.89%),influenza A virus and rhinoviruses 1 sample(0.94%),respiratory syncytial virus B,parainfluenza3 virus and influenza A virus 1 sample (0.94%),respiratory syncytial virus B and rhinoviruses 1 sample (0.94%);43 samples (40.57%) were positive for at least one bacteria pathogen,streptococcus pneumoniae 28 samples (26.42%), haemophilus influenzae 8 samples (7.55%), streptococcus pneumoniae and haemophilus influenzae 6 samples (5.66%),haemophilus influenzae, streptococcus pneumoniae and mycoplasma pneumoniae 1 sample (0.94%).Of the total, virus-and-bacteria mixed infection 16 samples (15.09%),influenza A virus and streptococcus pneumoniae 3 samples (2.83%), influenza A virus and haemophilus influenzae 3 samples (2.83%), rhinoviruses and streptococcus pneumoniae 5 samples (4.72%),rhinoviruses and haemophilus influenzae 1 samples (0.94%),respiratory syncytial virus B and streptococcus pneumoniae 1 sample (0.94%),rhinoviruses, respiratory syncytial virus B and streptococcus pneumoniae 1 sample (0.94%), coronavirus 229E/NL63,haemophilus influenzae and streptococcus pneumoniae 1 sample (0.94%),influenza A virus, respiratory syncytial virus B,parainfluenza3 and streptococcus pneumoniae 1 sample (0.94%).3 The influence of virus on COPD patients The average recovery time in virus- positive group was 31.59d (95%CI: 15.88~47.31), and in virus- negtive group was 14.82d (95%CI:12.81~16.83). Log-rank test showed that the recovery rate of two groups was significantly different (χ2=5.17,P=0.02).4 The influence of infection on inflammatory cytokines The concentration of IL-6(114.92±44.82ng/L) in sputum samples of virus- positive group was higher than in virus-negtive group(70.74±46.59ng/L),but TNF-αwas not significantly different between both groups.The concentration of IL-6 and TNF-αin sputum was not significantly different between bacteria-positive and bacteria-negtive group. The concentration of IL-6 in sputum of bacteria-virus mixed infection group(120.31±46.62ng/L)was higher than bacteria or virus single infection group (83.61±47.83ng/ L),P=0.02. Conclusions: influenza virus A, rhinoviruses, Streptococcus pneumoniae and haemophilus influenzae infection are important factors for AECOPD patients. Virus infection would lower recovery rate, prolong recovery time and increase the concentration of inflammatory cytokines of airway. A-type influenza virus is worth paying attention to.