title: Epidemiology and clinical profiles of Mycoplasma pneumoniae infection in hospitalized infants younger than one year.
abstract: BACKGROUND
  Mycoplasma pneumoniae (M. pneumoniae) is an important pathogen of community-acquired pneumonia in children, but the epidemiology and clinical features of M. pneumoniae infection in infants are reported in only a few studies. This study aims to evaluate possible age-related differences in the presenting clinical features in infants with M. pneumoniae infection.
  
  
  METHODS
  24-month longitudinal study on lower respiratory tract infection (LRTI) caused by M. pneumoniae, confirmed by both serology and polymerase chain reaction, was performed. Medical records of patients were reviewed for demographic, clinical and microbiological characteristics.
  
  
  RESULTS
  Out of 2174 infants with LRTI admitted to the Children's Hospital Affiliated to Soochow University in Jiangsu Province, 80 were diagnosed with M. pneumoniae infection. We found that 15 were aged 1 to <5 months; 29 were aged 5 to <9 months; and 36 were aged 9 to <12 months. M. pneumoniae infection mainly occurred in August to October. The presence of fever with a maximum temperature of >39.0 °C for ≥3 days was more common in the 9 to <12 month age group (P < 0.05). Laboratory tests showed that the infants aged 9-12 months had a higher peripheral leukocyte (P = 0.035) and neutrophil (P = 0.015) count and a higher CRP level (P = 0.041). Moreover, the median length of hospitalization for infants aged 1 to <5 months was shorter than that in the other two groups.
  
  
  CONCLUSIONS
  Our work provides important clinical information about infants with M. pneumoniae infection and highlights that younger infants with M. pneumoniae infection may have a milder clinical course than older infants.
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China.
authors.forename: Huiming
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China.
authors.forename: Zhengrong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China.
authors.forename: Yongdong
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China.
authors.forename: Meijuan
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Respiratory Medicine, Children's Hospital of Soochow University, No. 303 Jing De Road, Suzhou, Jiangsu, China. Electronic address: szdxjiwei@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
mesh_terms: D002681:China / Q000453:epidemiology; D060085:Coinfection / Q000097:blood / Q000453:epidemiology / Q000382:microbiology; D017714:Community-Acquired Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification*; D011019:Pneumonia, Mycoplasma / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology; D012189:Retrospective Studies; D012621:Seasons
keywords: Infant; Infection; Mycoplasma pneumonia