[Usefulness of a chromogenic selective agar for the identification of Bacillus cereus isolated from blood cultures].
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.
Jeong
Eun Sun
ES
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Shin
Jong Hee
JH
Shin
Myung Geun
MG
Suh
Soon Pal
SP
Ryang
Dong Wook
DW
D000293:Adolescent; D000328:Adult; D000362:Agar / Q000737:chemistry; D000368:Aged; D001409:Bacillus cereus / Q000302:isolation & purification*; D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D002863:Chromogenic Compounds / Q000737:chemistry*; D003470:Culture Media; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
D002863:Chromogenic Compounds; D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D000362:Agar