Application Of Bronchoalveolar Fluid Loop-Mediated Isothermal Amplification In Etiological Examination Of Pneumonia In Children

Objective: To analyze the etiology distribution and multiple infection of children patients with severe pneumonia,prolonged pneumonia and refractorily treated pneumonia in Shiyan area,and compare the difference in the positive rates with loop-mediated isothermal amplification,culture method and serologic antibody detection to provide references for clinicians in the pediatric department to diagnose and treat the severe pneumonia,prolonged pneumonia and refractorily treated pneumonia in early phase.Methods:124 children patients with severe pneumonia,prolonged pneumonia and refractorily treated pneumonia hospitalized in the Pediatric Department of Shiyan Renmin Hospital between September 2018 and September 2020 were retrospectively analyzed.All the children patients were detected for pathogenic bacteria in the respiratory tract with bronchoalveolar fluid loop-mediated isothermal amplification,and the results were made statistical analysis respectively with the results of sputum culture detection and the results of mycoplasma pneumoniae antibody detection in serum to compare the difference in the positive rates,and analyze the distribution of etiology of the detection results with loop-mediated isothermal amplification.Results:In 124 specimens,46 cases were detected positive wmycoplasma pneumoniaeith loop-mediated isothermal amplification(37.1%)and 24 cases were detected positive with sputum culture(19.4%),the difference in the positive rates with these two methods has a statistical significance(χ~2=9.633,P < 0.05).12 cases were detected mycoplasma positive with loop-mediated isothermal amplification(9.7%)and65 cases were detected mycoplasma pneumoniae positive with serological specific antibody detection(52.4%),the difference in the positive rates with these two methods has a statistical significance(χ~2=52.907,P<0.05).In 124 cases detected with loop-mediated isothermal amplification,46 cases were detected positive(37.0%),38 cases were detected with a single infection(82.6%),and 8cases were detected with multiple infections(17.4%).In the cases with a single infection,the positive rate of streptococcus pneumoniae was the highest(30.4%),next were mycoplasma(26.1%),staphylococcus aureus(8.7%),haemophilus influenzae(8.7%),acinetobacter baumannii(4.3%),pseudomonas aeruginosa(2.2%)and stenotrophomonas maltophilia(2.2%).The chlamydia pneumoniae,legionella pneumophila and mycobacterium tuberculosis complex were not detected out.In the cases with multiple infections,there were 5 cases infected with two pathogenic bacteria,wherein,4 cases infected with staphylococcus aureus + methicillin-resistant staphylococcus,and 1 case infected with haemophilus influenzae + streptococcus pneumoniae;there was one case infected with three pathogenic bacteria,namely,staphylococcus aureus + haemophilus influenzae + methicillin-resistant staphylococcus;and there were 2 cases infected with four pathogenic bacteria,namely,escherichia coli +haemophilus influenzae + klebsiella pneumoniae + acinetobacter baumannii.The difference in the positive rate of pathogenic bacteria in different age groups had a statistical significance(χ~2=10.67,P<0.05),the age group of 1～3 years old had the highest positive rate(32/64,50.0%),and the pathogenic bacteria with the highest positive rate was streptococcus pneumoniae.The difference in the positive rate of pathogenic bacteria in different seasons had a statistical significance(χ~2=15.11,P <0.05),spring had the highest positive rate(19/29,65.5%),and the pathogenic bacteria with the highest positive rate was streptococcus pneumoniae.In the severe pneumonia group,there were 21 cases detected positive(21/67,31.3%),wherein,16 cases with a single infection and 5 cases with mixed infections.The highest positive rate of a single infection was streptococcus pneumoniae(9.0%),while the highest positive rate of multiple infections was staphylococcus aureus+methicillin-resistant staphylococcus(3.0%);the difference in the positive rate of pathogenic bacteria in different age groups had a statistical significance(χ~2=7.979,P<0.05),and the age group of 1～3 years old had the highest positive rate(43.6%);the difference in the positive rate of pathogenic bacteria in different seasons had a statistical significance(χ~2=11.813,P<0.05),and spring had the highest positive rate(60.0%).In the prolonged pneumonia group,there were 8 cases detected positive(8/20,40.0%),all detected with a single infection,and the mycoplasma has the highest positive rate;The difference in the positive rate of pathogenic bacteria in different age groups had a statistical significance(χ~2=9.048,P<0.05),the age group of 1～3 years old had the highest positive rate(71.4%);and the difference in the positive rate of pathogenic bacteria in different seasons had no statistical significance(P>0.05).In the refractorily treated pneumonia group,there were 17 cases detected positive(17/37,45.9%),wherein,14 cases with a single infection,3 cases with mixed infection,and the streptococcus pneumoniae had the highest positive rate;the difference in the positive rate of pathogenic bacteria in different age groups had no statistical significance(P>0.05);and the difference in the positive rate of pathogenic bacteria in different seasons had a statistical significance(χ~2=13.323,P<0.05),and spring had the highest positive rate(100.0%).Conclusion: The loop-mediated isothermal amplification,sputum culture and serological mycoplasma antibody detection had differences in the positive rate of pathogenic bacteria,and could be used for the early pathogen detection in pneumonia.The common pathogenic bacteria in the severe pneumonia,prolonged pneumonia and refractorily treated pneumonia in children in Shiyan area were streptococcus pneumoniae,mycoplasma,staphylococcus aureus and haemophilus influenzae,different ages,different seasons and different pathogenic bacteria had differences in the positive rate.