Usefulness of a Chromogenic Selective Agar for the Identification of Bacillus cereus Isolated from Blood Cultures

다국어 초록 (Multilingual Abstract)

Background : The incidence of Bacillus cereus bacteremia is increasing, but the identification of Bacillus species remains difficult. Brilliance Bacillus cereus agar (BBC agar; Oxoid, UK) is a new CHROMagar medium that allows selective isolation and identification of B. cereus; however, its clinical usefulness is seldom studied. We evaluated the usefulness of BBC agar to identify B. cereus isolates recovered from blood cultures.
Methods : We analyzed a total of 53 blood isolates that showed a Bacillus-like morphology on Gram staining. All isolates were identified by using both the API Coryne (bioMérieux, France) and API 50CH/B (bioMérieux) systems. They were subsequently subcultured on BBC agar, incubated for 24 hr, and then examined for characteristic blue-green colonies. The clinical characteristics of patients whose isolates were identified as B. cereus were assessed.
Results : Of the 53 isolates, 18 were identified as B. cereus by API 50CH/B. With the API 50CH/B system used as gold standard, the sensitivity and specificity for the identification of B. cereus were 100% (18/18) and 100% (35/35), respectively, using BBC agar, and 67% (12/18) and 100% (35/35),respectively, using the API Coryne system. Of the 18 patients with B. cereus bacteremia, 15 showed infectious signs, and 3 had more than 2 blood cultures positive for B. cereus on separate days.
Conclusions : Our study shows, for the first time, that BBC agar, with its good agreement and ease of use, is a valuable alternative to the API 50CH/B system for the presumptive identification of B. cereus isolates from blood cultures. (Korean J Lab Med 2010;30:394-9)

참고문헌 (Reference)

1 Gaur AH, "The expanding spectrum of disease caused by Bacillus cereus" 20 : 533-534, 2001

2 Hernaiz C, "Nosocomial bacteremia and catheter infection by Bacillus cereus in an immunocompetent patient" 9 : 973-975, 2003

3 John AB, "Intractable Bacillus cereus bacteremia in a preterm neonate" 53 : 131-132, 2007

4 Weber DJ, "In vitro susceptibility of Bacillus spp. to selected antimicrobial agents" 32 : 642-645, 1988

5 Logan NA, "Identification of Bacillus strains using the API system" 130 : 1871-1882, 1984

6 Miller JM, "Fulminating bacteremia and pneumonia due to Bacillus cereus" 35 : 504-507, 1997

7 Lee YL, "Fatal spontaneous bacterial peritonitis and necrotizing fasciitis with bacteraemia caused by Bacillus cereus in a patient with cirrhosis" 59 : 242-244, 2010

8 Fricker M, "Evaluation of standard and new chromogenic selective plating media for isolation and identification of Bacillus cereus" 121 : 27-34, 2008

9 Lee CC, "Clinical significance of potential contaminants in blood cultures among patients in a medical center" 40 : 438-444, 2007

10 Weber DJ, "Clinical significance of Bacillus species isolated from blood cultures" 82 : 705-709, 1989

11 Hilliard NJ, "Bacillus cereus bacteremia in a preterm neonate" 41 : 3441-3444, 2003

12 Gaur AH, "Bacillus cereus bacteremia and meningitis in immunocompromised children" 32 : 1456-1462, 2001

13 Logan NA, "Bacillus and other aerobic endospore-forming bacteria. In: Murray PR, Baron EJ, et al, eds. Manual of clinical microbiology. 9th ed" American Society for Microbiology 455-473, 2007