CLINICAL COMPARISON OF ISOLATOR AND THIOL BROTH WITH ESP AEROBIC AND ANAEROBIC BOTTLES FOR RECOVERY OF PATHOGENS FROM BLOOD

The recovery of pathogens and the speed of their detection were determ ined for our conventional blood culture system (an Isolator [Wampole] and a 100-ml Thiol bottle [Difco]) compared with automated ESP aerobic and anaerobic bottles (80 ml each; Difco). Each of the four culture d evices was inoculated with approximately 10 ml of blood from symptomat ic patients weighing more than 80 lb (ca. 36 kg). From 7,070 sets of c ultures for 2,841 patients, 607 clinically significant isolates were r ecovered: 456 (75.1%) from the Isolator, 353 (58.2%) from Thiol, 377 ( 62.1%) from ESP aerobic bottles, and 346 (57.0%) from ESP anaerobic bo ttles. Of the 607 isolates, 149 (24.5%) were detected only with the co nventional system (Isolator and/or Thiol), and 65 (10.7%) were detecte d only with the ESP two-bottle system (P < 0.001). Our conventional sy stem allowed for detection of significantly more isolates of members o f the family Enterobacteriaceae (P < 0.001), Staphylococcus aureus (P < 0.01), Staphylococcus spp. (coagulase-negative) (P < 0.01), and Ente rococcus spp. (P < 0.05), and ESP facilitated detection of significant ly more isolates of S. pneumoniae (P < 0.01). When all four devices in a culture set were positive for the same isolate, no microbial specie s or group was detected significantly earlier (greater than or equal t o 24 h) by either blood culture system. The Isolator contamination rat e (4.8%) was greater than or equal to 6 times the rate for any of the bottles. Of pathogens detected by the Isolator, 50% were recovered in counts of less than or equal to 1.0 CFU/ml and 18% were recovered only as a single colony. The ESP system offered an automated, less labor-i ntensive blood culture system for which routine subcultures were not r equired, but the important considerations of culturing large volumes o f blood and of obtaining at least two sets from each patient in our po pulation were reemphasized.