title: Concordance between qualitative and quantitative cultures in burned patients. Analysis of 2886 cultures.
abstract: OBJECTIVE
  To determine the concordance between superficial cultures (SC) and quantitative cultures (QC) in the diagnosis of wound infection in burn patients.
  
  
  METHODS
  
  
  
  METHODS
  All SC and QC taken from the same patient, site and during the same surgery were analysed.
  
  
  METHODS
  On the SC, the microorganism (MO) and its amount defined subjectively by the microbiologist was recorded (negative, very low, low, regular and abundant). On the QC, the MO and its amount were expressed as colony forming units per gram of tissue (CFUs/g).
  
  
  METHODS
  Kappa index of agreement beyond chance; Wilcoxon and Kruskall-Wallis for continuous variables and chi(2) for categorical variables were used with a p<0.05 indicating statistical significance.
  
  
  RESULTS
  One thousand four hundred and forty three pairs of cultures were analyzed. The concordance between SC and QC (Kappa index) was 52%. On the SC, only when the microbiologist subjectively informed "abundant" MOs there was a significant difference (p<0.0001). There were 6.1% of QCs with more than 10(5) CFUs/g and the most frequent MOs isolated were: S. aureus (27.9%), E. coli (11.6%), P. aeruginosa (11.6%), E. faecalis (11.6%) and S. epidermidis (7.0%).
  
  
  CONCLUSIONS
  SC has a moderate concordance with the QC showing a low reliability between the two methods. The subjective information given by the microbiology technician in the SC is not precise. A study in which the two methods be compared blindly against the reference standard, in a prospective cohort of patients, it is needed to discriminate which of two methods it is the most accurate one determining sensitivity and specificity.
authors.affiliation: Burn and Plastic Surgery Unit, Hospital del Trabajador de Santiago, Santiago, Chile. drstefandanilla@gmail.com
authors.forename: Stefan
authors.initials: S
authors.lastname: Danilla
authors.forename: Patricio
authors.initials: P
authors.lastname: Andrades
authors.forename: María E
authors.initials: ME
authors.lastname: Gómez
authors.forename: Marcela
authors.initials: M
authors.lastname: Chamorro
authors.forename: Patricio
authors.initials: P
authors.lastname: Leniz
authors.forename: Jose L
authors.initials: JL
authors.lastname: Piñeros
authors.forename: Sergio
authors.initials: S
authors.lastname: Llanos
authors.forename: Hector
authors.initials: H
authors.lastname: Roco
authors.forename: Gerardo
authors.initials: G
authors.lastname: Correa
authors.forename: Juan A
authors.initials: JA
authors.lastname: Pasten
authors.forename: Alex
authors.initials: A
authors.lastname: Eulufi
authors.forename: Ricardo
authors.initials: R
authors.lastname: Roa
authors.forename: Wilfredo
authors.initials: W
authors.lastname: Calderon
mesh_terms: D001424:Bacterial Infections / Q000175:diagnosis*; D001707:Biopsy, Needle / Q000379:methods; D002056:Burns / Q000382:microbiology*; D002478:Cells, Cultured / Q000382:microbiology; D006801:Humans; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014946:Wound Infection / Q000175:diagnosis* / Q000382:microbiology