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Volume 10, Number 9—September 2004

Computer Algorithms To Detect Bloodstream Infections

William E. Trick*Comments to Author , Brandon M. Zagorski†, Jerome I. Tokars*, Michael O. Vernon†, Sharon F. Welbel†‡§, Mary F. Wisniewski†‡, Chesley Richards*, and Robert A. Weinstein†‡§
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †Chicago Antimicrobial Resistance Project, Chicago, Illinois, USA; ‡Cook County Hospital, Chicago, Illinois, USA; §Rush Medical College, Chicago, Illinois, USA

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Table 1

Computer algorithms and corresponding NNIS system definitions to categorize blood culture isolates, September 2001–February 2002, Cook County Hospital, Chicago, Illinoisa

Determinationb Computer rule NNIS definitions
Hospital acquired
(A) Acquired blood culture >3 days after hospital admission
No evidence infection present or incubating at time of hospital admission, unless infection was related to previous admission to this hospital
Infection (B1) Microbiology data: pathogen other than CSCc cultured from blood, or >2 CSC isolates recovered from blood within 5 days of initial positive blood culture Patient has at least one sign or symptom: fever (>38°C), chills, or hypotension and at least one of the following:
pathogen cultured from >1 blood cultures, CSC cultured from >2 blood cultures drawn on separate occasions, CSC cultured from at least 1 blood culture from patient with intravenous line, and physician institutes appropriate antimicrobial drug therapy

(B2) Microbiology and pharmacy data: pathogen cultured from blood or >2 CSCd isolates within 5 days of initial positive blood culture, or CSC cultured from blood once and vancomycin administered within 3 days before until 1 day after isolate identification
Secondary bloodstream infection (BSI)d
(C1) Time restricted: organism recovered from blood also recovered from a nonblood culture, 3–7 days after the blood culture acquisition dated The organism cultured from the blood is related to an infection at another site
(C2) Length of stay: organism recovered from blood also recovered from a nonblood culture during the entire length of stayd
Central-venous catheter (CVC) associatede (D) No algorithm developed, all BSI were considered CVC associated Vascular access device that terminated at or close to heart or one of great vessels within the 48-hour period before BSI developed

aNNIS, National Nosocomial Infection Surveillance; CSC, common skin contaminant; BSI, bloodstream infection.
bFor each determination, if the computer rule or NNIS definition was not met, the isolate was considered as one the following: community acquired, a contaminant, primary BSI, or not CVC associated.
cWe used the examples of CSCs listed in the NNIS manual: diphtheroids, Bacillus spp., Propionibacterium spp., coagulase-negative staphylococci, or micrococci.
dCatheter tip and stool cultures were excluded for both algorithms. CSCs had to be cultured from a wound for the BSI to be considered as a secondary BSI.
eIncludes tunneled or nontunneled catheters inserted into the subclavian, jugular, or femoral veins; pulmonary artery catheters; hemodialysis catheter; totally implanted devices (ports); peripherally inserted central catheters; and introducer sheaths.

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Page created: March 25, 2011
Page updated: March 25, 2011
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