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Objective:To compare the laboratory diagnostic methods of Mycoplasma pneumonia(MP) and evaluate its clinical value.Methods:A prospective study.Throat swabs and double sera of children with MP infection were collected from December 2016 to January 2017 in Shengjing Hospital Affiliated to China Medical University; throat swab samples of healthy children aged 3 to 5 in Chaoyang District, Beijing were collected from March to May 2017.Passive agglutination (PA) was used to detect the double serum.Taking the 4-fold increase or decrease of the specific antibody titer of the double serum as the gold standard, the receiver operating characteristic curve (ROC) was drawn, and the laboratory methods for detecting MP infection were compared and evaluated.Results:(1)A total of 93 children with MP infection were clinically diagnosed, including 42 males (45.2%) and 51 females (54.8%), with an average age of 5.5 years.Sixty cases (64.5%) of MP infection were diagnosed.There were 349 healthy children, 198 males and 151 females, with an average age of 4.3 years.The positive rate of throat swab culture was 0.6% (2 cases), and the positive rate of fluorescent quantitative PCR(qPCR) was 18.9% (66 cases). (2) The culture specificity was the highest (100.0%) and the sensitivity was the lowest (65.0%). PA and enzyme linked immunosorbent assay (ELISA) were used to detect a single serum in the acute phase, the sensitivity was 71.7% and 86.5% respectively.ROC curve suggested that the current clinical diagnostic threshold MP specific antibody IgM ≥ 1∶160 was not the best diagnostic threshold.Molecular biological diagnostic methods were the most sensitive, RNA simultaneous and testing (SAT) was 85.0% and qPCR was 93.0%; while the specificity was low, 75.7% (SAT) and 63.6% (qPCR), respectively.(3) At the same time, MP nucleic acid (SAT, PCR) of throat swabs and a single serum (ELISA, PA) of children in acute phase were detected, the sensitivity was increased to 95.0%-100.0%, and the specificity was 63.6%-75.7%.Conclusions:Molecular biology is highly sensitive in diagnosing MP infection.It has asymptomatic infection or is carried after infection.Whether it needs treatment needs to be combined with clinical practice, when MP detection is positive.The detection of a single serum in the acute phase with a course of about 1 week has high sensitivity and is of reference value for the diagnosis of MP infection, but the diagnosis needs to be combined with clinical practice.The sensitivity and accuracy of detecting MP infection by single serological test combined with SAT in acute phase are higher than that by single application.
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Objective:To investigate the common bacteria in the oropharynx of children with Mycoplasma pneumoniae pneumonia (MPP) and its clinical significance.Methods:A total of 134 children with MPP who were hospitalized in the Department of Pediatric Respiratory, Shengjing Hospital of China Medical University from December 2016 to June 2017 were selected as the research subjects, and 42 healthy children in the same hospital were selected retrospectively as the healthy control group during the same period.Fluorescent quantitative polymerase chain reaction Taqman probe was used to detect common oropharyngeal bacteria[ Streptococcus pneumoniae(SP), Moraxella catarrhalis(CTA), Haemophilus influenza(HI)] for the enrolled children.Firstly, the bacterial detection rate of MPP children and healthy children was compared.Then, according to age(<1 years old, 1-<3 years old, 3-<6 years old and 6-14 years old), bacterial detection[Mycoplasma pneumoniae(MP), MP+ bacteria]and bacterial species(MP+ SP, MP+ CTA, MP+ HI), 134 children with MPP were divided into groups to compare.Moreover, the relevant clinical datas were retrospectively analyzed by rank sum test and chi- square test. Results:Among 134 children with MPP, 79 (58.96%) children were detected bacteria, and 17 (40.48%) children were detected bacteria among 42 healthy children, with statistically significant differences( χ2=4.404, P<0.05). Compared with the MP group, the level of white blood cell (WBC)[8.5(6.7, 12.0)×10 9/L vs.7.8(5.8, 9.3)×10 9/L, Z=-2.232], C reactive protein(CRP)[19.2(7.2, 35.0) mg/L vs.8.4(3.4, 24.6) mg/L, Z=-2.810], lactate dehydrogenase(LDH)[286(244, 365) U/L vs.250(210, 302) U/L, Z=-2.474] and the incidence of lobar pneumonia[40.51%(32/79 cases) vs.18.18%(10/55 cases), χ2=7.510], pleural effusion[13.92%(11/79 cases) vs.3.64%(2/55 cases), χ2=3.917], refractory Mycoplasma pneumoniae pneumonia (RMPP)[34.18%(27/79 cases) vs.18.18%(10/55 cases), χ2=4.151] in MP+ bacteria group were higher; the course of fever[10(7, 12) d vs.8(6, 10) d, Z=-2.706] and duration of antibiotic use[16(13, 19) d vs.12(9, 16) d, Z=-3.747] in MP+ bacteria group were longer (all P<0.05). The level of WBC in MP+ SP group[12.20(7.80, 17.30)×10 9/L] was higher than that in MP+ HI group [6.75(5.37, 9.44)×10 9/L], and the differences were statistically significant( Z=11.574, P<0.05), and the incidence of lobar pneumonia in MP+ SP group [56.67%(17/30 cases)]was higher than that in MP+ CTA group [0(0/3 cases)]and MP+ HI group[18.75%(3/16 cases)], and the differences were statistically significant( χ2=9.770, P<0.05). Conclusions:Bacterial colonization or infection is more likely to occur in the oropharynx of children with MPP.When WBC, CRP, and LDH are significantly increased and the image shows a large consolidation or pleural effusion, it may indicate mixed bacterial infection, longer course of fever and higher incidence of RMPP, and the common mixed bacteria is SP.
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Objective:To investigate drug resistance gene in Mycoplasma pneumoniae(MP) and the distribution of 13 respiratory pathogens in bronchoalveolar lavage fluid(BALF) of children with Mycoplasma pneumoniae pneumonia(MPP).Methods:A total of 100 BALF of children with MPP in Peking University Third Hospital and Peking University First Hospital from January 2018 to January 2019 were collected.Fluorogenic quantitative PCR was used to detect nucleic acid and it′s drug resistance gene of MP and multiple PCR method was adopted to detect influenza A virus, influenza A virus-H 1N 1, influenza A virus-H 3N 2, influenza B, human parainfluenza virus, adenovirus, human bocavirus, human rhinovirus, Chlamydia pneumoniae, human metapneumovirus, MP, human coronavirus, and respi-ratory syncytial virus gene, and the results were compared by using Chi square test. Results:In 100 BALF samples, MP and drug resistance gene were detected by fluorogenic quantitative PCR.Totally, 83 cases (83.00%) were MP positive and 78 cases (93.98%) were drug resistant.All of them had the point mutations A2063G in V region of 23S rRNA domain.A total of 13 kinds of respiratory pathogens were detected by multiplex PCR method, and 89 cases (89.00%) were positive.Totally, 79 cases (79.00%) were MP positive, of which 74 cases (74.00%) detected only MP, and 5 cases (5.00%) detected MP combined with other pathogens.Other pathogens were detected in 10 cases (10.00%). The virus detection rate of 0-4 years old group was higher than that of >4-6 years old group ( P=0.042) and >6 years old group ( P=0.002), and the differences were statistically significant. Conclusions:MP can be detected in most BALF samples of MPP children, the drug resistance phenomenon is serious, and the main point mutation is A2063G.There were other respiratory pathogens and 2 or 3 pathogens were detected in a small number of BALF samples.
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Objective:To understand the pathogen distribution of children with influenza in North China in the past 2018-2019 years, and compare the accuracy of influenza virus antigen test results with that of influenza virus nucleic acid test results, provide reference data for clinical use good influenza virus pathogen detection methods.Methods:Five hundred and eighty throat swab samples of influenza-like children in 10 hospitals, northern China, were collected from December 2018 to January 2019.Each sample was tested by rapid influenza diagnostic test and reverse-transcription polymerase chain reaction(RT-PCR).Results:Of all 580 clinical samples, 256 positive samples (256/580 cases, 44.14%)were detected by the influenza rapid influenza diagnostic test, of which 235 were pure influenza A(235/256 cases, 91.8%), 21 cases were pave influenza B(21/256 cases, 8.2%), and 324 case were negative samples(324/580 cases, 55.86%). No cases were detected positive A and B at the same time.Of all 580 samples were detected using the A /B influenza virus RT-PCR, and a total of 353 cases(353/580 cases, 60.9%) were positive (of which 242 cases were influenza virus antigen-positive), of which 311 were pure A influenza(311/353 cases, 88.1%) and 41 were pure B influenza(41/353 cases, 11.6%), 1 case of mixed infection of A and B(1/353 cases, 0.3%), and 227 cases were negative(227/580 cases, 39.1%). In 324 cases of influenza virus antigen negative samples, 111 cases(111/324 cases, 34.3%) were positive for influenza virus nucleic acid.The detection rate of influenza A in Taiyuan was 23.2% (22/95 cases), and the detection rate of influenza B was 43.2% (41/95 cases), which was significantly different from other regions.With reverse-transcription polymerase chain reaction detection as the standard, the diagnostic value of influenza pathogen detection reagents was evaluated.The sensitivity, specificity, missed diagnosis rate, misdiagnosis rate, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, Youden index and area under the receiver operating characteristic curve were 68.56%, 93.83%, 31.44%, 6.17%, 94.53%, 65.74%, 11.12, 0.335, 0.624 and 0.812.Conclusions:From December 2018 to January 2019, the majority of children′s influenza in northern China is influenza A virus.Except Taiyuan which is dominated by influenza B. Influenza virus nucleic acid detection has high sensitivity and specificity for diagnosing influenza, and also has the ability to distinguish virus subtypes.Influenza virus antigen detection has a certain diagnostic value, a good specificity (93.83%), sensitivity (68.56%) which needs to be further improved, and a certain rate of missed diagnosis (31.44%) needs to be paid attention to possible missed diagnosis.Detecting positive cases of influenza virus antigens should be given a fast and effective anti-viral treatment, while the negative cases, especially those at high risk for influenza complications, should be confirmed influenza virus RT-PCR as soon as practical.
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Objective To investigate the antibacterial effect of Fusidic acid on Mycoplasma pneumoniae and antibiotic resistant Mycoplasma pneumoniae in vitro.Methods Twenty-eight clinical strains of Mycoplasma pneumoniae isolated from patients with respiratory tract infection at Beijing Friendship Hospital Affiliated to the Capital University of Medical Sciences from January to December 2016 and 2 Mycoplasma pneumoniae reference strains were enrolled.The minimum inhibitory concentration (MIC) of Fusidic acid and Azithromycin were determined by using micro-dilution ration method.The chessboard method was used to check the antibacterial effect of combination between Fusidic acid and Azithromycin.The antibacterial activity of the Fusidic acid was evaluated by measuring the antibacterial rate of different concentrations.Results One isolate showed no mutation in 23SrRNA,26 isolates had one point mutation in loci 2063 and 1 isolate had one point mutation in loci 2064 among the 28 clinical isolates.The findings by micro-dilution method results showed that the MIC values of all the clinical isolates with mutations associated with macrolide resistance to Azithromycin were ＞ 1.000 0 mg/L,and the MIC values of all the clinical isolates with no mutations to azithromycin were ＜ 0.500 0 mg/L.The findings by micro-dilution method results showed that the MIC value of Fusidic acid for Mycoplasma pneumonia and drug resistance Mycoplasma pneumoniae was 1.000 0 mg/L.The Fractional Inhibitory Concentration index of Fusidic acid and Azithromycin combination was ≤0.500 0 mg/L.When the concentration of the Fusidic acid was lower than or equal to 32 MIC,the antibacterial effect of Fusidic acid against Mycoplasma pneumoniae increased with its higher concentration.When the concentration of the Fusidic acid was lower than or equal to 8 MIC,the longer the strain was exposed to the drug,the stronger antibacterial effect was against Mycoplasma pneumoniae.Conclusion If the treatment of Mycoplasma pneumoniae infection is not effective or the infection of patient is combined with bacteria,the application or combination of Fusidic acid may inhibit pathogenic bacteria effectively.Of course,how to use Fusidic acid in clinical treatment needs further study and discussion.
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Objective To developed A laboratory diagnosis of Moraxella catarrhalis by an laboratories diagnostic method real-time fluorescence quantitative PCR assay. Methods The specific primers and probes were designed based on the sequence of outer membrane protein CopB(copB)gene in Moraxella catarrhalis,and the Taqman probe RT-PCR method was developed to detect the Moraxella catarrhalis.The standard plasmids ex-tracted from the Moraxella catarrhalis standard strains were used to constitute the standard samples,and compared with these standard samples,the sensitivity of the fluorescence quantitative PCR assay was tested by the estab-lished standard curves.The specificity of the fluorescence quantitative PCR assay was tested by the DNA samples of other bacterias in the laboratory.Meanwhile,321 throat swab samples from inpatient and outpatient child pa-tients,with asthma infection were collected as clinical samples to validate the fluorescence quantitative PCR as-say.Results The standard curve was drawn in the real-time PCR by the Taqman fluorescence reporter.During the sensitivity tests,the newly-developed real-time fluorescence PCR could detect at least 10 copies of Moraxella catarrhalis,and could successfully distinguish several DNAs of the pathogens.On the basis of the validation result of the 321 throat swab samples,there are 25 Moraxella catarrhalis with 7.79 % positive rate.Conclusion The fluorescence quantitative PCR assay is of great sensitivity and specificity,and it can be widely used for the detec-tion of Moraxella catarrhalis.
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Objective To determine pathogens and epidemiological characteristics of adults with acute respiratory infection (ARI) in Beijing area.Methods During 2015,a total of 2 700 cases of ARI were sampled and detected for 9 respiratory pathogens including Legionella pneumophila type1 (LP1),mycoplasma pneumoniae (MP),qrickettsia (COX),chlamydia pneumoniae (CP),adenovirus (ADV),respiratory syncytial virus (RSV),influenza virus type A and B (INFA,IFVB) and parainfluenza viruses type1,2 and 3 (PIVs) using indirect fluorescence immunoassay.Results A total of 620 cases of ARI were tested positive with positive rate of 22.97％ (620/2 700).MP had the highest prevalence followed by LP1,INFB,COX,CP,PIVs,INFA,ADV and RSV in turn.There were 109 cases found mixed infection with the proportion of 17.58％ (109/620).Mixed infection of LP1 along with MP was the most common pattern.The highest detection rate of pathogens was observed in November,whereas the lowest in April in terms of months (x2 =31.288,P＜ 0.01).Different pathogens had distinct prevalent features.The prevalence of male was significant higher than that of female (x2 =6.402,P =0.011).As for stratificated by age,the middle-aged people had the highest infection rate (x2 =9.094,P=0.059).There was no significant difference between the out-and in-patient in terms of infection rate (x2 =0.114,P=0.736).Conclusion MP,LP1 and INFB accounted for ARI of adults in Beijing area during 2015.
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Objective To investigate the clinical characteristics of adult patients with community acquired pneumonia (CAP) caused by acute Mycoplasma pneumoniae (MP) infection, and provide evidence for early identification of MP infection. Methods A prospective, multicenter and cross-sectional study was conducted. 452 adult patients with CAP admitted to Beijing Friendship Hospital, Beijing Guangwai Hospital and Air Force General Hospital from August 2011 to October 2015 were enrolled. The diagnosis of adult MP infection was confirmed by the combined application of double serum antibody titer and MP-DNA nested polymerase chain reaction (PCR) through testing serum and throat swab samples from patients to identify acute infections, past infections, pathogen carrying, and non-MP infection. The clinical characteristics of patients with acute MP infection were summarized by analyzing the baseline data, clinical parameters and chest imaging findings in patients with non-MP infection and acute MP infection. Results Of 452 enrolling patients with CAP, 288 patients (63.7%) suffered from MP infection, and 164 patients (36.3%) with non-MP infection. There were 56 patients (12.4%) with acute infection, 10 patients (2.2%) with past infections, 222 patients (49.1%) with pathogen carriers in MP infective patients indicating susceptible to MP in adult patients. There were no significant differences in gender, age, fever extent, duration of fever, sputum production, shortness of breath, rales, underlying diseases, etc. between non-MP infection and acute MP infection patients, which suggested that the baseline data of the two groups were equilibrium. The acute infection rates of MP in summer and autumn (43.9% and 43.5% respectively) were more than those in spring and winter (13.3% and 12.3% respectively). It was shown by laboratory examination results that serum cardiac troponin T (cTnT) increased significantly in acute MP infectious patients more than that in non-MP infection patients (30.4% vs. 9.8%, P < 0.01), which indicated that patients with acute MP infection were more likely to have myocardial injury. While there were no significant differences in blood routine, blood electrolytes, blood glucose, as well as heart, liver and kidney function between the two groups. It was shown by chest imaging that the diffuse lesions (57.1% vs. 37.2%), mediastinal lymphadenopathy (60.7% vs. 37.8%) were less founded in the middle lobe of the right lung (12.5% vs. 32.9%), which were the main manifestations in patients with acute MP infection as compared with non-MP infection patients with statistical difference (all P < 0.01). There were no significant differences in the chest imaging performances of pulmonary ground glass shadow, lobar and segmental consolidation, patch shadow, a shadow, acinar nodules, grinding glass density nodules, the photic zone, hilar lymphadenopathy and pleural effusion occurrence between the two groups. Conclusion Adult CAP patients are easy to carry MP, myocardial damage is a common complication in acute MP infectious patients which are characteristic of image findings of diffuse lung disease, mediastinal lymphadenopathy and less founded in the middle lobe of the right lung.
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Objective To develope a new Real-time quantitative PCR assay using SYBR green as fluorescence reporter, which is rapid, specific, sensitive, cheap and accurate for the detection of mycoplasma pneumoniae(MP), and evaluated its clinical application value.Methods The sequence of the 23S rRNA gene in MP type strain FH was selected as amplified regions, and specific primers were designed.Then the related plasmids were extracted as standards,and the absolute quantitative standard curve was established.The sensitivity ,specificity of the fluorescence quantitative PCR assay was compared with the nest-PCR and kit;To calculate correlation coefficient, coincidence rate and kappa coefficient, clinical samples were detected using above-mentioned methods and cultivation,respectively.Results The detection sensitivity of the new real-time PCR and nest-PCR was 10 copies of FH DNA,while the kit 100 copies.In the specificity tests,the MP sample was positive,while mycoplasma hominis and other four bacteria were all negative.We applied this real-time PCR assay ,nest-PCR, kit and cultivation to 182 clinical specimens, and the detection rates were 55.49％, 52.75％, 47.25％ and 39.01％ ,respectively.The total consistency rate and Kappa coefficient of the new real-time PCR method and nest-PCR were 89.6％ ,0.790, respectively;while those of the new method and cultivation were 83.5 ％ ,0.678, respectively.The total consistency rate and Kappa coefficient of the new real-time PCR method and the kit were 89.6％ ,0.792,respectively;and the correlation coefficient of these two methods was 0.923,P ＜ 0.001.Conclusion Compared with other methods, the new real-time PCR assay could be used to detect mycoplasma pneumoniae quickly and economically, with high sensitivity and specificity ,revealing great utility value on varied instrumentation platforms.
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Mycoplasma pneumoniae(MP) is a common pathogen found in respiratory tract infections of children and is susceptible to macrolides, tetracycline, aminogly-cosides, and quinoloines . Of all these antibiotics, macrolides is the frist choice for children. However,in recent years, strains which are resistant to common drugs have been selected in vitro and isolated from patients Point mutation at antibitics target site of these 8trains is one of the molecular mechanisms.The study of MP resistance can provide theoretical guidance for rational choice of antibiotics and application.
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Objective To investigate status of macrolide resistance and determine molecular mechanisms in Mycoplasma pneumoniae.Nethods All of 370 throat swab specimens were cultured to isolate Mycoplasma pneumoniae.Mycoplasma pneumoniae isolates were identified by nested PCR for specific 16SrRNA gene.Antibiotic susceptibility test was done to identify acrolide resistant strains.23SrRNA gene wag amplified by nested PCR followed by direct automatic sequencing method.The DNA sequences were compared to the sequence of Mycoplasma pneumoniae M129(accession no.X68422)to find molecular mechanisms of drug resistance.Results Fifty clinical strains were isolated from 370 specimens.Of 50 strains.4 strains were susceptible to macrulide,46 strains were macrolide resistant with the percentage of 92%.MICs of resistant strains to erythromycin.Azithromycin and josamycin were elevated.The sequence of 23SrRNA gene in 4 Susceptible strains and the reference strain FH was identical to Mycoplagma pneumoniae gene in GenBank.46 resistant strains arbored a point mutation respectively,among them,40 strains had all A to G transition at position 2063.1 strain had an A to C transition at position 2063,the other five strains showed an A to G transition at position 2064.Conclusions Macrolide resistance in Mycoplasma pneumoniae iS very serious health conceru.The point mutation in 23SrRNA.Xpecailly predominant position 2063 mutation contributed to the macrolide resistance in Mycoplagma pneumoniae.The MICs of resistant strains to erythromycin,azithromycin and iosamycin are much higher than Mycoplasma pneumoniae reference strain FH.