title: Primary subacute hematogenous osteomyelitis in children: a clearer bacteriological etiology.
abstract: BACKGROUND
  This study aimed to describe the spectrum of pediatric primary subacute hematogenous osteomyelitis (PSAHO) and to investigate its bacterial etiology.
  
  
  METHODS
  Sixty-five consecutive cases of PSAHO admitted to our institution over a 16-year period (2000-2015) were retrospectively reviewed to assess their laboratory and radiographic imaging features, as well as their bacteriological etiology.
  
  
  RESULTS
  On evaluation, white blood cell count and C-reactive protein were normal in 53 (81.5 %) and 34 cases (52.3 %), respectively, whereas the erythrocyte sedimentation rate was superior to 20 mm/h in 44 cases (72.1 %). Blood cultures failed to identify the pathogen in all but one patient, and classic bone sample cultures only managed to isolate the pathogen in five cases (11.6 %). Use of polymerase chain reaction (PCR) assays on bone aspirates or blood allowed the causative microorganism to be isolated in a further 22 cases. Using classic cultures and PCR assays together resulted in pathogen detection in 27 cases (62.8 % of the children bacteriologically investigated), with Kingella kingae being the most frequently reported microorganism.
  
  
  CONCLUSIONS
  Two distinct forms of PSAHO should be distinguished on the basis of age of patients and bacteriological etiology. The infantile form affects children aged between 6 months and 4 years and is predominantly due to K. kingae. The juvenile form involves children aged >4 years and Staphylococcus aureus appears to be the main bacteriological etiology. Appropriate nucleic amplification assays drastically improve the detection rate of the microorganisms responsible for PSAHO.
  
  
  METHODS
  Case series, level IV.
authors.affiliation: Service of Pediatric Orthopedics, Department of Child and Adolescent Medicine, University Hospitals of Geneva, 6, rue Willy Donzé, Geneva 14, 1211, Switzerland.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Spyropoulou
authors.affiliation: Pediatric Radiologic Unit, University Hospitals of Geneva, Geneva 14, 1211, Switzerland.
authors.forename: Amira
authors.initials: A
authors.lastname: Dhouib Chargui
authors.affiliation: Pediatric Radiologic Unit, University Hospitals of Geneva, Geneva 14, 1211, Switzerland.
authors.forename: Laura
authors.initials: L
authors.lastname: Merlini
authors.affiliation: Service of Pediatric Orthopedics, Department of Child and Adolescent Medicine, University Hospitals of Geneva, 6, rue Willy Donzé, Geneva 14, 1211, Switzerland.
authors.forename: Eleftheria
authors.initials: E
authors.lastname: Samara
authors.affiliation: Service of Pediatric Orthopedics, Department of Child and Adolescent Medicine, University Hospitals of Geneva, 6, rue Willy Donzé, Geneva 14, 1211, Switzerland.
authors.forename: Raimonda
authors.initials: R
authors.lastname: Valaikaite
authors.affiliation: Service of Pediatric Orthopedics, Department of Child and Adolescent Medicine, University Hospitals of Geneva, 6, rue Willy Donzé, Geneva 14, 1211, Switzerland.
authors.forename: Georgios
authors.initials: G
authors.lastname: Kampouroglou
authors.affiliation: Service of Pediatric Orthopedics, Department of Child and Adolescent Medicine, University Hospitals of Geneva, 6, rue Willy Donzé, Geneva 14, 1211, Switzerland. dimitri.ceroni@hcuge.ch.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Ceroni
keywords: Etiology; Kingella kingae; MSSA; Microbiology; Osteomyelitis; Subacute