Case report and seeded blood culture study of Brucella bacteremia

Abstract

Diagnosis of brucellosis requires prompt detection and identification of the coccobacillus for appropriate patient management, as the organism is associated with a potentially severe outcome. In a recent experience, an 18-year-old migrant farm worker presented at a local hospital with nonspecific symptoms. A significant Brucella titer of 2,560 was followed by the recovery of a gram-negative coccobacillus, subsequently identified as Brucella abortus, from subcultured 5-day-old BACTEC NR730 negative blood cultures. The organism proved to be susceptible to a variety of antimicrobial agents and resistant to nitrofurantoin. The patient was administered antimicrobial therapy for Brucella spp. consisting of tetracycline and streptomycin for 21 days. During the course of therapy the patient experienced defervescence and was discharged with the recommendation for periodic follow-up examinations. Seeded culture studies of this isolate with fresh human blood and target inocula of 5 and 500 CFU/ml indicated that the larger (500-CFU/ml) inoculum produced positive instrument detection within 2 days, whereas the smaller (5-CFU/ml) inoculum required 5.5 to 7.5 days for detection, depending on the medium used. These findings underscore the potential for Brucella bacteremia to escape instrument detection given a low bacterial inoculum.

Processing of peripheral blood progenitor cell components in improved clean areas does not reduce the rate of microbial contamination

“…In general, this culture system can be considered as very sensitive method for the detection of microbial contamination. Earlier studies have demonstrated detection rates down to one colony‐forming unit of fastidious bacteria by using this system 28,29 …”

Detection of Brucella melitensis by the BacT/Alert automated system and Brucella broth culture

“…Roiz et al [11], using the BacT/Alert system, reported that, in their experience, all nine cultures obtained from five patients yielded the organism [15], also using BACTEC 9240, recovered 93% of 97 isolates in 5 days. Zimmerman et al [16], using BACTEC NR 730, reported that the growth time of Brucella spp. was inversely related to the concentration of bacteria; and they found that if the concentration was 5-500 CFU/mL, B. melitensis growth in BACTEC NR 730 would be within 2 days, whereas 5-7 days would be required for detection if the concentration was lower than 5 CFU/mL.…”

Detection of Brucella melitensis by BACTEC NR660 blood culture system

“…As the result of effective infection control measures implemented by health authorities, brucellosis has become a rare disease in North America and parts of western Europe. Because of that, published experiences with modern blood culture techniques, and particularly with the BACTEC system, for the detection of Brucella organisms are limited to a few reports of small outbreaks of the disease among travelers to countries where brucellosis is endemic (3,9).…”