Retrospective Pathogen Diagnostic Investigation For Severe Pneumonia Via Loop-mediated Isothermal Amplification

Objective：Loop-mediated isothermal amplification (LAMP) technology is used to establishthe respiratory tract pathogen rapid detection technology system study of severepneumonia, aimed at improving more pathogen detection capability to guidediagnosis and treatment, and compared with conventional clinical pathogenic bacteriadetection method (such as sputum culture), to explore the effectiveness of theproposed method and the clinical practical, to provide rapid and accurate method foretiology diagnosis and guide targeted therapy.Methods:Retrospective analysis25cases of pneumonia in critically ill patients who weretreated in Respiratory Medicine and Intensive Care Unit of First Affiliated Hospital ofNanchang University from March2013to February2014.Using LAMP method todetect the lower respiratory tract pathogen different time periods according to thecourse of the disease，then compared with sputum culture.LAMP can detect13kindbacteria and atypical pathogens simultaneously, including: Streptococcus pneumonia,Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Pseudomonasaeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia, Haemophilusinfluenzae, Legionella pneumophila, mycoplasma pneumonia, Chlamydia pneumonia,Mycobacterium tuberculosis and MRSA. To understand the pathogen spectrum ofsevere pneumonia in hospitalized patients under the results of LAMP.Combined theLAMP results with other informations like the clinical data and treatment effect toanalyze the effectiveness of this method.To explore the lamp gene chip technology asa new test method to guide antibiotic drugs.Results:We collected82specimens, the overall detection rate of LAMP was70.7%, andthe detection of mixed infection rate of39.0%;The whole detection rate of sputumculture was63.4%, and the mixed bacterial detection rate was18.3%; Both the overall detection rate and mixed bacterial detection rate with LAMP was higher thanthat of sputum culture (P <0.05). According LAMP test results,the main pathogen ofsevere pneumonia patients in hospitalized was gram-negative bacilli,while MRSAinfection was increasing and gradually tends to the community-acquired. LAMP haveadvantages of atypical pathogens detection. LAMP can also distinguish betweenbacterial infection and bacterial colonization, endotracheal intubation or tracheotomywould increase colonization bacterial infection, The most commonly detectedcolonized pathogen after endotracheal intubation or tracheotomy was Pseudomonasaeruginosa. The initial antibiotic treatment of severe pneumonia in hospitalizedpatients with combined therapy was better, and carbapenems was the most widelyused. LAMP might be able to response the clinical therapeutic effect.Conclusion:LAMP as a new type of rapid pathogen detection technology can provideetiology diagnosis basis for clinical treatment more accurately and faster than sputumculture, and it can distinguish between pathogenic bacteria and bacterial colonization,tracheal intubation or tracheotomy will increases bacterial colonization infection;LAMP detection result showed that Gram-negative bacilli has become a majorpathogen of severe pneumonia;The initial treatment of severe pneumonia is combined therapy, the most widelyused is the carbapenems; LAMP reaction might be able to response the results of theclinical therapeutic effect.