ANALYSIS OF 281,797 CONSECUTIVE BLOOD CULTURES PERFORMED OVER AN 8-YEAR PERIOD - TRENDS IN MICROORGANISMS ISOLATED AND THE VALUE OF ANAEROBIC CULTURE OF BLOOD

The results for 281,797 blood culture sets of specimens collected from adult patients at the Mayo Clinic over an approximately 8-year period (1 November 1984 through 30 November 1992) were analyzed in order to determine whether there were differences in the types of microorganism s isolated over this time and to assess the usefulness of anaerobic cu lturing of blood. Each blood culture set consisted of two aerobic bloo d cultures (Septi-Chek [Becton Dickinson, Sparks, MD] and Isolator [Wa mpole Laboratories, Cranbury, NJ]) and one anaerobic culture (nonvente d tryptic or trypticase soy broth [NVTSB; Difco Laboratories, Detroit, or Becton Dickinson]). The relative frequency of isolation of aerobic and facultatively anaerobic gram-positive bacteria and obligately ana erobic bacteria increased over the second half of the 1984-1992 survei llance period. The value of the NVTSB anaerobic blood culture was demo nstrated for diagnosing bloodstream infections caused by certain facul tatively anaerobic bacteria in addition to obligately anaerobic bacter ia and supported the inclusion of the NVTSB anaerobic blood culture as a standard part of the three-component blood culture set used at this institution.