title: The clinical characteristics and genotype distribution of Chlamydia trachomatis infection in infants less than six months of age hospitalized with pneumonia.
abstract: BACKGROUND
  Chlamydia trachomatis is a common sexually-transmitted bacterial pathogen. As no routine screening is performed during pregnancy, neonates and infants are at high risk for C. trachomatis infection. The objective of this study was to investigate the morbidity, clinical characteristics and genotype distribution of C. trachomatis pneumonia in infants less than six months of age.
  
  
  METHODS
  Clinical manifestations and laboratory results were recorded. Respiratory sputum specimens were tested using RT-PCR targeting C. trachomatis cryptic plasmid. Simultaneously, respiratory virus antigens were detected by direct immunofluorescence and bacterial pathogens were examined by culture in all sputum samples. Positive C. trachomatis samples were further genotyped using a multiplex PCR reverse line blot assay. The relationship between genotype and pneumonia severity was explored.
  
  
  RESULTS
  Of 1408 infants, 101 (7.2%) were infected with C. trachomatis. Sixteen of 101 (15.8%) were assessed as severe pneumonia. These severe cases had a higher proportion of viral co-infection (37.5%) compared to mild pneumonia cases (9.4%, P<0.05).Infants with tachypnea (OR 9.2) and wheezing (OR 3.5) were more likely to be classified as severe pneumonia (P<0.05). Amongst 66 C. trachomatis specimens for which a genotyping result was available, seven genotypes were detected, and 39.4% of these specimens contained two or three genotypes. Overall, genotype E (48.5%) was the most frequent, followed by genotype F (42.4%), J (31.8%), D (12.1%), K (10.6%), G (4.5%) and H (3.0%). There were no significant correlations of particular genotypes with severity of disease, although there was a weak indication that more severe pneumonia might be associated with having certain mixed genotypes of C. trachomatis.
  
  
  CONCLUSIONS
  The prevalence of C. trachomatis in the population of young hospitalized infants with pneumonia in Shenzhen was very high. The relationship between genotype distribution and severity of pneumonia was not clear based on this study due to small sample size. Further in-depth investigation correlating genotype and disease severity based on a larger population is needed.
authors.affiliation: Department of Neonatology, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China.
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Li
authors.affiliation: Central Laboratory, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China. Electronic address: Xionglk@sina.cn.
authors.forename: Likuan
authors.initials: L
authors.lastname: Xiong
authors.affiliation: Department of Neonatology, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Central Laboratory, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Central Laboratory, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Neonatology, Baoan Maternal and Child Health Hospital, Shenzhen 518133, China.
authors.forename: Fen
authors.initials: F
authors.lastname: Xu
authors.affiliation: Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia; Centre for Infectious Diseases and Microbiology, Westmead Hospital, Westmead, Australia.
authors.forename: Matthew V N
authors.initials: MV
authors.lastname: O'Sullivan
mesh_terms: D015373:Bacterial Typing Techniques; D002690:Chlamydia Infections / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D060085:Coinfection; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D005838:Genotype; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011014:Pneumonia / Q000453:epidemiology / Q000382:microbiology*; D015995:Prevalence; D011446:Prospective Studies
chemical_list: D004269:DNA, Bacterial
keywords: Chlamydia trachomatis; Genotyping; Reverse line blot hybridization