title: The challenge of anticipating catheter tip colonization in major heart surgery patients in the intensive care unit: are surface cultures useful?
abstract: OBJECTIVE
  Patients undergoing heart surgery show a high risk of catheter colonization and catheter-related bloodstream infections. We evaluated whether skin insertion site and catheter hub surveillance cultures ("surface cultures") could predict catheter colonization and help establish the origin of bloodstream infections.
  
  
  METHODS
  : Prospective cohort study.
  
  
  METHODS
  An 11-bed heart surgery intensive care unit in a tertiary university hospital.
  
  
  METHODS
  Heart surgery patients spending >4 days in intensive care over an 11-month period.
  
  
  METHODS
  All catheters were surveyed. Cultures were obtained from the skin insertion site and all hubs on day 5 after surgery, every 72 hrs thereafter, and on catheter removal. Swabs were processed semiquantitatively by streaking the surface of a Columbia agar plate. Catheters were processed using Maki's method. The observation of > or = 15 colonies/plate was taken to indicate a positive skin or catheter colonization culture result.
  
  
  RESULTS
  Over the study period, 561 catheters were inserted in 130 patients. The median time a catheter was in place was 6 days (interquartile range 3-11), and 3,712 surface cultures were obtained (median four per patient). Catheter colonization occurred in 133 catheters, and there were 15 episodes of catheter-related bloodstream infection (incidence density of colonization 29.3 and of catheter-related bloodstream infection 8.8 per 1,000 catheter-days). Validity indexes for the capacity of surface cultures to predict catheter colonization and catheter-related bloodstream infection, respectively, were as follows: accuracy, 71.4, 65.6; sensitivity, 83.5%, 100%; specificity, 67.1%, 64.7%; positive predictive value, 47.6%, 7.2%; negative predictive value, 91.9%, 100%; positive likelihood ratio, 2.5, 2.83; and negative likelihood ratio, 0.2, 0. Surface cultures correctly predicted 77.4% of all bacteremia episodes (catheter-related and non-catheter-related).
  
  
  CONCLUSIONS
  Systematic surveillance cultures of catheter hub and skin insertion sites in patients admitted to a heart surgery intensive care unit could help identify patients who would benefit from decontamination and preventive measures and establish whether catheters are the portal of entry of bloodstream infection.
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Universidad Complutense, Madrid, Spain. ebouza@microb.net
authors.forename: Emilio
authors.initials: E
authors.lastname: Bouza
authors.forename: Patricia
authors.initials: P
authors.lastname: Muñoz
authors.forename: Almudena
authors.initials: A
authors.lastname: Burillo
authors.forename: Javier
authors.initials: J
authors.lastname: López-Rodríguez
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernández-Pérez
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Pérez
authors.forename: Cristina
authors.initials: C
authors.lastname: Rincón
mesh_terms: D016470:Bacteremia / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control; D006348:Cardiac Surgical Procedures; D002408:Catheters, Indwelling / Q000009:adverse effects*; D003666:Decontamination; D004866:Equipment Contamination; D006801:Humans; D007362:Intensive Care Units; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012867:Skin / Q000382:microbiology; D013997:Time Factors