Etiological Investigation Of An Outbreak Of Acute Infectious Pneumonia In Young Students

Background Since severe acute respiratory syndrome coronaviruses and influent virus A infection outbreak in 2003, more and more reports fever of unknown origin or infectious pneumonia were documented throughout the word. Out of them mycoplasma pneumoniae (MP ) is a common cause of outbreaks, which accounts for approximately 50% of all community-acquired pneumonia. Influent virus A/B and L. pneumophila were also the common causes for community-acquired pneumoniae (CAP). Respiratory tract infections occurred commonly in winter and spring. M. pneumoniae infection spreads rapidly in day-care centre, jail, cruise ship and military camp. The typical respiratory infection caused by M. pneumoniae is a slowly developed pulmonary and extra-pulmonary manifestations, such as immune thrombocytopenia, erythema nodosum, acute glomerulonephritis, reversible myeloradiculopathy, and recurrent arterial thrombosin. The high rate of morbidity reinforces the needs for correct diagnosis in time for administering proper antibiotic treatments. However, it's difficult to identify the pathogens at the early time of the outbreak. We tried to establish the real-time PCR assays for detecting 5 common respiratory infection pathogens for the rapid diagnosis in this settings. In this study we conducted unbiased high-throughput sequencing, real-time PCR assays as well as serological assays for final identifying the pathogens of an outbreaks of respiratory infections.Objective To establish 5 real-time PCR assays for detection of 5 common respiratory pathogens in conscripts with fever in a military camps; and also aimed to confirm the cause of an outbreak of acute infectious pneumonia at biomolecular and serological level.Methods Double sera from seventy-one patients at acute and recovery stage of illness were obtained respectively and detected by ELISA. Real-time PCR assays for detecting five respiratory pathogens were established based on their relevant reference strains. DNA and RNA from the serum were abstracted , then the polymerase-chain-reaction with specific primer to human influenza virus A and B, L. pneumophila, severe acute respiratory syndrome coronaviruses, human Coronaviruses OC43/229E (hCoV OC43/229E)and mycoplasma pneumoniae, were conducted simultaneously by unbiased high-throughput sequencing, which was analyzes by Solesa system, for identifying microbial sequences.Results The specific detection in 71 acute stage sera showed that sixteen(22%) were anti-MP IgM and/or anti-MP IgG positive. And in our specific real-time PCR detections with specific primers and probes showed the negative results; In 582750 reads amplified by unbiased high-throughput sequencing, none was specific for viral sequences. The further analysis as compared in Solexa system also revealed the negative findings for human influenza virus A, M. pneumoniae, L. pneumophila, SARS CoV, hCoV(OC43/229E)and human rhinovirus.Conclusions Sixteen patients were diagnosed as mycoplasma pneumoniae infections and the morbidity is 22%(16/71), while cause of this outbreak of acute infectious pneumonia in a trainning camp can not be identified by serological and biomolecular methods. Unbiased high-throughput sequencing got an negative result, as we know that obtaining appropriate specimens in times is a key for etiological study. So, we didn't get respiratory swabs might be the most likely reason for the negative genetic testing.