Volume 10, Number 9—September 2004
Research
Computer Algorithms To Detect Bloodstream Infections
, Brandon M. Zagorski†, Jerome I. Tokars*, Michael O. Vernon†, Sharon F. Welbel†‡§, Mary F. Wisniewski†‡, Chesley Richards*, and Robert A. Weinstein†‡§
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.