Epidemiological And Clinical Study On Mycoplasma Infection In Children With Respiratory

Part 1 Epidemiological characteristics of mycoplasma pneumoniaewith respiratory tract infection and the relationship betweenmeteorological factors in hospitalized children from 2006 to 2013Objective: To study the epidemic characteristics of mycoplasma pneumoniae with acute respiratory tract infection in hospitalized children and its relationship of meteorological factors in suzhou.Method: Sputum was obtained from hospitalized children with acute respiratory tract infections(ARI) during Jan 2006 to Dec 2013. Nasopharyngeal aspirates were obtained from children according to a standard protocol and were tested for syncytial virus infection(RSV), influenza virus A(IVA), influenza virus B(IVB), parainfluenza virus(PIV) I, PIV II, PIV III, and adenovirus(ADV) with direct immunofluorescence assay. Samples were tested human metapneumovirus(h MPV) with reverse transcription polymerase chain reaction(RT-PCR).Human bocavirus(h Bo V) and Mycoplasma pneumoniae(MP) DNA were detected by real-time fluorescent PCR. Sputum culture for bacteria. Detection of serum MP-specific antibody was performed using enzyme-linked immunosorbent assay. The meteorological factors including average monthly temperature,relative humidity, rainfall amount, sum of sunshine and mean wind velocity were collected. The relationship between the detection of MP and metrorological factors was analyzed by linear regression and stepwise regression analysis.Results:1. During the study period, 15098 specimens were tested. The positive rate of MP, bacteria and respiratory virus were 28.1%(4246/15098)、28.7%(4333/15098)、30.3%(4575/15098), respectively. 18.9%(2854/15098) of the patients had mixed infection. The most common pathogen was MP(28.1%), followed by RSV(15.1%), Streptococcus pneumoniae(11.2%), h Bo V(6.7%) and Haemophilus influenza(4.2%).2. Of the 4246 MP positive patients, 2309(24.7%) were male, 1937(33.7%) were female. The positive rate in female was significant higher than that in male(χ2=142.49, P<0.01). The positive rates of the age groups of 0-6 months, ~12 months, ~36months, ~60months and >60 months were 10.2%、21.6%、34.8%、45.1% and 59.9%, respectively. The positive rates increased with age, with a statistical significance for age distribution(χ2= 1990, P <0.001). Patients >60 months had the highest positive rate.3. The positive rates of MP during 2006 to 2013 were 25.1%(487/1938)、32.6%(671/2057)、39%(790/2023)、41%(842/2052)、19.1%(319/1667)、7.5%(151/2001)、27.6%(486/1762)、31.3%(500/1598), respectively. The positive rates of MP during these years differed significantly(χ2=811.8, P <0.01). The positive rates in 2008 and 2009 were the highest, while the rates in 2012 and 2013 were the lowest. The positive rates increased with years, with a statistical significance for year distribution from 2006 to 2009. However, they deceased significantly in 2010 and 2011 and increased in 2012 and 2013 with a lowest positive rate in 2011 during the 8 years.4. The results showed that the positive rates of MP infection were 25.3% in spring, 33.7% in summer, 32.8% in autumn and 20.8% in winter. These data revealed that the prevalence of MP infection was obviously higher during summer and autumn than in spring and winter(χ2=212.61, P <0.01).5. The positive rate of MP showed a moderate correlation with average monthly temperature(r=0.3388,P =0.000) and a low correlation with average monthly sunshine(r=0.241,P=0.018) and(r=0.207,P=0.043) rainfall.While it showed no correlation with average monthly humidity and wind velocity. In stepwise regression analysis temperature was the only independent covariant significantly associated with positive rate of MP(β = 0.380,t = 3.983,,P = 0.000). The meteorological factors had a lag period effect for the positive rate of MP. The positive rate of MP increased by 0.65% with a 1 mm increase in the average monthly rainfall. The effect was significant at the lag periods of 2 and 3months.6. Of the 4246 patients with MP infection, 1142(29.88%) patients were co-infected with other pathogens. 21.08% were co-infected with respiratory virus, while 8.8% were co-infected with bacteria. The most common pathogen co-infected was Streptococcus pneumoniae(6%), followed by RSV(5.3%) and h Bo V(5%).Conclusions:1. MP was the most common pathogen in respiratory tract infection of hospitalized children in Suzhou.2. The positive rates increased with the age. Patients >60 months had the highest positive rate. The positive rate in female was higher.3. Epidemic outbreaks of MP infection occur lasting for 4 years and at intervals of 2 years from 2006 to 2013.4. The prevalence of MP infection was higher during summer and autumn.5. The epidemic of MP showed a correlation with meteorological factors, especially average temperature. Average monthly rainfall had a lag period effect for the positive rate of MP.6. Co-infection was common in patients with MP infection. The most common pathogen co-infected was Streptococcus pneumoniae, RSV and h Bo V.Part 2 Clinical characteristics of Mycoplasma pneumoniaepneumonia in children of different agesObjective: To study the differences of the clinical characteristics of Mycoplasma pneumoniae pneumonia(MPP) in children of different ages.Methods: We retrospectively reviewed the medical records of MPP patients hospitalized in Children’s Hospital of Soochow University during January 2006 and December 2013. All patients were divided into five groups according to their ages: < 6 months, ~1 year, ~3 years, ~5 years and > 5 years of age. Clinical symptoms, pulmonary manifestations, chest radiography and laboratory values were collected and analyzed.Results:1. Of 3358 MPP patients, 412(12.3%) patients were in the age group of < 6 months, 423(12.6%) ~1 year, 1033(30.8%) ~3 years, 733(21.8%) ~5 years and 757(22.5%) > 5 years of age.2. Fever was less frequently seen in MPP patients < 6 months(20.9%) and mostly were low-to-moderate fever. The proportion of fever increased with age and peaked in patients > 5 years(83.6%). They mostly presented as high fever and the difference reached the statistical significance(χ2= 1990.49, P= 0.000). Most of the patients < 6 months, ~1 year and ~3 years presented with wet cough while the majority of patients ~5 and > 5 years group presented with dry cough with a significant difference(χ2=123.2,P= 0.000). The proportion of wheezing in different age groups were significantly different(P< 0.05). 57.9% of the patients aged between 6 months and 1 year of age had wheezing, significantly higher than the other age groups(P= 0.000). The proportion of wheezing were 41.9% in < 6 months, 57.9% in ~1 year and 41.2% in ~3 years, respectively, significantly higher than ~ 3 years and >5 years patients(χ2= 436.78, P= 0.000). In patients >5 years aged group, only 7.8% had wheezing. In patients < 6 months, the proportion of tachypnea, cyanosis and hyoxemia were higher than the other groups(P= 0.000). The proportion of rales in <6 months, ~1 year and ~3 years were 90.3%, 93.6% and 88%, significantly higher than ~5 years and > 5 years group(χ2= 1180.72, P= 0.000).3. Pulmonary complications including the proportion of pleural effusion in > 5 years group was significantly higher than other groups(χ2= 149.09, P= 0.000). Extrapulmonary complications including the proportion of skin lesion in ~5 years and > 5 years groups were significantly higher than <6 months, ~1 year and ~3 years groups(χ2= 57.69, P= 0.000). The proportion of gastrointestinal tract lesion in <6 months group were significantly higher than other groups(χ2= 24.78, P= 0.000). The proportion of cardiovascular system lesion in <6 months, ~1 year and ~3 years groups were significantly higher than ~5 years and > 5 years groups(χ2= 118.81, P= 0.000). The proportion of hematological system lesion in ~5 years and > 5 years groups were significantly higher than <6 months, ~1 year and ~3 years groups(χ2= 103.83, P= 0.000).4. 95.4% of <6 months, 96.2% of ~1 year, 90.9% of ~3 years, 84.6% of ~ 5 years and only 38.2% of >5 years of patients presented as bronchopneumonia in radiology, reaching statistical significance(χ2= 1002.11, P= 0.000). On the other hand, segmental/labor pneumonia were more frequently seen patients > 5 years of age than other groups with a significant difference(χ2= 1242.81, P= 0.000). Besides, pleural effusion and atelectasis were seen in 10.2% and 12.9% in this groups, also significantly higher than other groups(χ2= 154.7, P= 0.000, χ2= 149.09, P= 0.000, respectively).5. The white blood cell and platelet count of < 6 months and ~1 year were higher than others while neutrophils proportion and c-reaction protein of ~5 years and > 5 years were higher than others, both with a P= 0.000(χ2= 26.21, 53.63, 229.27, 34.94, respectively). Moreover, the serum levels of alanine transaminase in ~3 years, ~5 years and > 5 years patients were higher than the others(χ2= 32.39, P= 0.000) and serum levels of creative kinase-MB in < 6 month, ~1 year and ~3 years patients were higher than the others with significant difference(χ2= 118.81, P=0.000).6. The levels of CD3+ in ~3 years and ~5 years patients were lower than others(χ= 5.74, P= 0.000). However, the levels of CD3+CD4+ showed no difference among all the groups(χ2= 1.37, P> 0.05). The levels of CD4+CD8+ in <6 months were lower than others(χ2= 5.39, P= 0.000). Levels of CD3-CD19+ in ~5 years and >5 years were lower than <6 months and ~1 year(χ2= 3.57, P= 0.000). In patients < 6 months, levels of CD3-CD19+, CD19+CD23+ and CD4+CD25+ were all higher than the other groups(All P= 0.000).Conclusion:1. MPP in patients under 3 years of age is not rare.2. MPP patients of different ages presented with different clinical characteristics, especially in patients < 6 months and > 5 years of age. MPP patients < 6 months usually presented with wet cough, wheeze, more pulmonary signs, lighter pulmonary radiologic presentations, higher rates of extrapulmonary complications with gastrointestinal tract and cardiovascular system lesion and a lighter inflammatory response while patients > 5 years usually presented with dry cough, high fever, more pulmonary signs, heavier pulmonary radiologic presentations, higher rates of extrapulmonary complications with skin and hematological system lesion and a stronger inflammatory response. Clinical presentations in patients between 3 and 5 years were in between.3. Cell immunity disorder was apparent in patients < 6 months with a hyperfunction of Th2 and B cells. In patients > 5 years of age, it most presented as a lower proportion of B cells and a higher level of natural killer cells.4. The difference of clinical characteristics in different age groups might indicate different pulmonary injury mechanism.Part 3. Clinical study on refractory mycoplasma pneumoniaepneumonia in childrenObjective:1.To summarize the clinical, laboratory, radiographic characteristics, morphological changes in electronic bronchoscopy and changes of bronchoalveolar lavage fluid(BALF) of refractory mycoplasma pneumoniae pneumonia(RMPP) and provide basis for early diagnosis of it.2.To study the levels and clinical significances of TNF-α, IFN-γ, IL-1β, c IL-4 and IL-10 in BALF in children with RMPP.Methods:1.Clinical characteristics, laboratory values and radiographic findings of 124 RMPP cases and 354 mycoplasma pneumoniae pneumonia(MPP) controls hospitalized in the Department of Respiratory Medicine in Children’s Hospital of Soochow University during January 2013 and December 2013 were analyzed.2.The electronic bronchoscopic data of 55 RMPP cases and 46 MPP cases were collected and the morphological changes and characteristics of BALF cytology, MP-DNA and cluture were further analyzed.3.We tested the levels of TNF-α, IFN-γ, IL-1β, IL-4 and IL-10 in BALF of 17 RMPP and 15 MPP children by ELISA and studied the relationship between the level of DNA and these cytokines.Result:1.The mean age of RMPP group was 71.6± 33.1 months when the mean age of MPP group was 30.6± 28.9 months. RMPP patients were significantly older than MPP patients(Z= 13.79, P< 0.05). No significant difference was found of male/female ratio between the two groups(c2= 2.72, P> 0.05).2.The ratio of fever ≥ 38.5℃ was higher in RMPP group(P< 0.01). The mean duration of fever was also longer in the RMPP group(P< 0.01). RMPP patients had significantly lower rates of wheeze and positive pulmonary signs than the MPP group(both P< 0.01). No significant difference was found in the rate of tachypnea, dyspnea, cyanosis and hyoxemia between the two groups(P> 0.05). RMPP patients were more frequently to be complicated by pleural effusion, skin and hematological system damages(P< 0.05).3.The median copies of sputum MP-DNA in RMPP patients were 2.4*107 copies/ml, significantly higher than that of 1*107 copies/ml in MPP patients with a P< 0.01. The median copies of BALF MP-DNA in RMPP patients were 2.5*107 copies/ml ranging from 2.5*107 to 2.5*107 copies/ml, significantly higher than that of 2.5*107 copies/ml ranging from 2.5*105 to 2.5*107 copies/ml in MPP patients with a P< 0.01.4.The levels of WBC count, neutrophils proportion, CRP, LDH, serum Ig A, Ig G and Ig M in RMPP patients were higher than those in MPP patients. The level of CD3+ T cells in RMPP patients were lower than that in MPP patients(P< 0.01) whereas the levels of CD16+56+ and CD19+CD23+ T cells were higher in RMPP patients(P< 0.01).5.The main pulmonary radiographic presentation in RMPP patients was labor pneumonia(82.3%), whose proportion was significantly higher than that of MPP patients(P< 0.01). The main pulmonary radiographic presentations in MPP patients were bronchopneumonia(75.9%) and interstitial pneumonia(7.9%), whose proportions were significantly higher than those of RMPP patients(P< 0.01). RMPP patients had a higher rate of pleural effusion than MPP patient(P< 0.01).6. The main presentations under bronchoscopy in RMPP patients were edema of the mucous membrane(69.1%), erosion of the mucous membrane(38.1%), inflammatory stenosis of the lumen(9.1%), follicular hyperplasia(7.3%), formation of sputum bolt(30.9%) and sputum bolt with bronchial cast(7.3%).7. The main cells in BALF of RMPP patients were neutrophils with a rate of 67.2±21.0%, significantly higher than that of MPP patients(42.9±27.3%)(P= 0.000). The proportions of macrophages in RMPP and MPP were 24.1±20.3%, 46.2±29.6%, respectively and the difference reached statistical significance(P= 0.000). The MP-DNA in BALF was in positive correlation with the level of neutrophils(r= 0.291, P= 0.003) and in negative correlation with the level of macrophages(r=-0.604, P< 0.001).8. The BALF levels of TNF-α, IFN-γ and IL-1β,In RMPP patients were higher than those in MPP patients(P< 0.05). No difference was found in the levels of IL-4 and IL-10 between the two groups(P> 0.05).9. No difference was found in the rate of co-infection between the groups(P> 0.05) and the main co-infected pathogens were streptococcus pneumoniae, haemophilus influenza, influenza virus A and adenovirus and so on.10. All RMPP and MPP patients received macrolide antibiotics(P> 0.05). Electronic bronchoscopy and bronchoalveolar lavage treatment were used more frequently in RMPP group than in MPP group(P= 0.000). The duration of hospitalization of RMPP patients were significantly longer than the MPP group(P= 0.000).Conclusion:1.RMPP was predisposed to older children and presented as higher fever with a longer fever duration, fewer pulmonary signs, higher serum levels of LDH and CRP, higher rates of skin and hematological system complications and longer duration of hospitalization.2.Most radiographic findings in RMPP patients were labor pneumonia, usually complicated by pleural effusion.3.Mucus hypersecretion could be the main presentation of RMPP in bronchoscopy. Differentiation of cytology of BALF revealed a neutrophil inflammation dominance and were positive correlated with the MP DNA load. Presentation under bronchoscopy and cytology of BALF are useful of diagnosing RMPP.4.TNF-α、IFN-γ、IL-1β might engage in the post infection immune reaction.5. The presence of RMPP was associated with the high load of MP DNA.6.Co-infection was not common in RMPP. The main co-infected pathogens were streptococcus pneumoniae, haemophilus influenza, influenza virus A and adenovirus.