RAPID IDENTIFICATION OF BACTERIALLY CONTAMINATED PLATELETS USING REAGENT STRIPS - GLUCOSE AND PH ANALYSIS AS MARKERS OF BACTERIAL METABOLISM

BACKGROUND: One in every 1000 units of platelets is bacterially contam inated, which puts patients at risk for transfusion-associated sepsis and death. However, there is currently no screening test in place to d etect contaminated units. The use of commercially available multiple-r eagent urine dipsticks for this purpose was evaluated. STUDY DESIGN AN D METHODS: Platelet concentrates were inoculated with either sterile s aline or suspensions of Staphylococcus aureus, Staphylococcus epidermi dis, Bacillus cereus, Klebsiella pneumoniae, or Serratia marcescens to a final concentration of 50 colony-forming units (CFU) per mt. The pl atelets were analyzed daily by the use of multiple-reagent strips, qua ntitative culture, and glucometry. RESULTS: B. cereus grew rapidly, re aching 10(7) CFU per mt I day after inoculation, while S. epidermidis grew slowly, achieving similar concentrations 4 to 6 days after inocul ation. Two of 10 dipstick reagents, glucose and pH, proved useful in d etecting bacteria. Both were lower in bacterially contaminated units t han in controls. Glucose data obtained from automated analyzers valida ted the dipstick data. All organisms were detected at concentrations g reater than or equal to 10(7) CFU per mt, and S. aureus and K. pneumon iae were detected in the range of 10(3) to 10(5) CFU per mt. CONCLUSIO N: The multiple-reagent test used had a sensitivity and specificity of 95 percent (greater than or equal to 10(7) CFU/mL) and 98 to 100 perc ent, respectively. These data indicate that urine dipsticks can be use d to rapidly and inexpensively detect bacterial contamination in plate let concentrates, which potentially will reduce morbidity and mortalit y at minimal cost.