title: The influence of Streptococcus pneumoniae nasopharyngeal colonization on the clinical outcome of the respiratory tract infections in preschool children.
abstract: BACKGROUND
  Streptococcus pneumoniae (SPn) is an important pathogen causing a variety of clinical manifestations. The effects of SPn nasopharyngeal colonization on respiratory tract infections are poorly studied. We evaluated the association of SPn colonization with features of respiratory tract infections.
  
  
  METHODS
  Children under the age of 6 years who visited a primary care physician because of respiratory tract infections were enrolled in the study. History was taken, children were clinically assessed by the physician, and nasopharyngeal swabs were obtained and cultured for SPn. Positive samples were serotyped. Associations of SPn colonization with clinical signs and symptoms, recovery duration, absence from day care centre, frequencies of specific diagnoses, and treatment with antimicrobials were evaluated.
  
  
  RESULTS
  In total 900 children were enrolled. The prevalence of SPn colonization was 40.8 % (n = 367). There were minor differences between male and female subjects (199 of 492, 40.4 % vs 168 of 408, 41.2 %, p = 0.825). Children with and without siblings had similar colonization rates (145 of 334, 43.4 % vs 219 of 562, 39.0 %, p = 0.187). Clinical signs and symptoms were not associated with SPn colonization. Children colonized with SPn had longer recovery duration compared to non-colonized children (114 of 367, 31.1 % vs 98 of 533, 18.4 %, p < 0.001) and were longer absent from day care (270 of 608, 44.4 % vs 94 of 284, 33.1 %, p = 0.001). Pneumonia, sinusitis, and acute otitis media were more frequently diagnosed in children colonized with SPn. Children attending day care centres had significantly higher prevalence of SPn colonization (270 of 367, 44.4 % vs 338 of 533, 33.1 %, p = 0.001). Children with pneumonia, sinusitis and acute otitis media were more frequently treated with antimicrobials than children with other diagnoses.
  
  
  CONCLUSIONS
  SPn nasopharyngeal colonization has a negative impact on the course of respiratory tract infection, likely because of SPn being the cause of the disease or a complicating factor. It is also associated with and may be responsible for higher frequencies of bronchitis, pneumonia, acute otitis media, sinusitis and the need of antimicrobial treatment.
authors.affiliation: Clinic of Children's Diseases, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. siga.petraitiene@gmail.com.|Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania. siga.petraitiene@gmail.com.
authors.forename: Sigita
authors.initials: S
authors.lastname: Petraitiene
authors.affiliation: Clinic of Children's Diseases, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. t.alasevicius@gmail.com.|Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania. t.alasevicius@gmail.com.
authors.forename: Tomas
authors.initials: T
authors.lastname: Alasevicius
authors.affiliation: Clinic of Children's Diseases, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. indre.cicenaite@gmail.com.|Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania. indre.cicenaite@gmail.com.
authors.forename: Indre
authors.initials: I
authors.lastname: Staceviciene
authors.affiliation: Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania. daiva.vaiciuniene@vuvl.lt.
authors.forename: Daiva
authors.initials: D
authors.lastname: Vaiciuniene
authors.affiliation: Department of Physiology, Biochemistry, Microbiology and Laboratory Medicine, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. tomas.kacergius@mf.vu.lt.
authors.forename: Tomas
authors.initials: T
authors.lastname: Kacergius
authors.affiliation: Clinic of Children's Diseases, Faculty of Medicine, Vilnius University, Vilnius, Lithuania. vytautas.usonis@mf.vu.lt.|Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania. vytautas.usonis@mf.vu.lt.
authors.forename: Vytautas
authors.initials: V
authors.lastname: Usonis
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002648:Child; D002656:Child Day Care Centers; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000175:diagnosis / Q000382:microbiology; D011014:Pneumonia / Q000175:diagnosis / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D065288:Serogroup; D012852:Sinusitis / Q000175:diagnosis / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents