Journal List > Korean J Lab Med > v.30(4) > 1011665

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Jeong, Shin, Shin, Suh, and Ryang: Usefulness of a Chromogenic Selective Agar for the Identification of Bacillus cereus Isolated from Blood Cultures
Original Article

Korean J Leg Med 2010;30(4):394-399.

Published online: 14 January 2010

DOI: https://doi.org/10.3343/kjlm.2010.30.4.394

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

Eun Sun Jeong, M.D., Jong Hee Shin, M.D., Myung Geun Shin, M.D., Soon Pal Suh, M.D., Dong Wook Ryang, M.D.

Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea

Corresponding author: Jong Hee Shin, M.D. Department of Laboratory Medicine, Chonnam National University Medical School, 671 Jaebong-ro, Dong-gu, Gwangju 501-757, Korea Tel: +82-62-220-5342, Fax: +82-62-224-2518 E-mail: shinjh@chonnam.ac.kr

∗ This study was supported by a grant (CR108045) from Chonnam National University Hospital Research Institute of Clinical Medicine.

      Revised 15 March 201015 May 2010       Accepted 22 July 2010

Copyright © 2010 Korean Society for Legal Medicine

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

Keywords: Bacillus cereus, Chromogenic agar, API 50CH/B system, Identification

REFERENCES

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Fig. 1.
Macroscopic morphology of Bacillus cereus (A) grown at 35°C on CHROMagar medium for 24 hr. Note the characteristic blue-green color of B. cereus, in contrast to other Gram-positive bacilli (B).
kjlm-30-394f1.tif
Table 1.
Identification of blood isolates of Bacillus cereus and related species using the API Coryne system, Bacillus cereus agar, and API 50CH/B
Identification results Bacillus cereus agar N of isolates
API Coryne API 50CH/B
Bacillus cereus Bacillus cereus Blue-green growth 12
Bacillus species Bacillus cereus Blue-green growth 3
Cellulomonas/Microbacterium Bacillus cereus Blue-green growth 3
Cellulomonas/Microbacterium Bacillus licheniformis No growth 16
Cellulomonas/Microbacterium Bacillus lentus No growth 3
Cellulomonas/Microbacterium Unacceptable profile No growth 3
Cellulomonas/Microbacterium Bacillus circulans No growth 2
Cellulomonas/Microbacterium Bacillus pumilus No growth 2
Cellulomonas/Microbacterium Bacillus subtilis/amyloliquefaciens No growth 2
Cellulomonas/Microbacterium Geobacillus stearothermophilus No growth 2
Cellulomonas/Microbacterium Aneurinibacillus aneurinilyticus No growth 1
Cellulomonas/Microbacterium Bacillus firmus No growth 1
Cellulomonas/Microbacterium Paenibacillus lautus/polymyxa No growth 1
Cellulomonas/Microbacterium Paenibacillus lautus No growth 1
Cellulomonas/Microbacterium Paenibacillus polymyxa No growth 1
Table 2.
Clinical features of 18 patients with Bacillus cereus bacteremia
Patient No. Age (yr) Sex Admission N of isolates Underlying disease Infectious signs∗ Central venous catheter Invasive procedures† Outcome
1 48 M MICU 1 DM, hypoglycemic coma + + - Unknown
2 68 F MW 1 Adrenal insufficiency + - - Improved
3 34 M SW 2 Hemoptysis + + + Improved
4 73 M SICU 1 Spondylodiscitis, epidural abscess + + + Improved
5 53 M MW 1 ARF + + + Improved
6 62 M MW 2 Bronchiectasis, hemoptysis + - - Improved
7 71 M MW 1 Acute pancreatitis + - - Improved
8 46 M MICU 1 Vibrio sepsis + + - Expired
9 27 M SICU 7 Hemoperitoneum, liver injury + + + Improved
10 47 F SICU 1 Subarachnoid hemorrhage - + + Improved
11 31 M MW 1 End-stage renal disease with kidney transplantation + + + Improved
12 0.1 M MW 1 Aspiration pneumonia + - - Improved
13 6 M MW 1 AGE - - - Improved
14 28 F MW 1 Cellulitis + - - Improved
15 13 M MW 1 Acute appendicitis + - - Improved
16 50 M MW 1 Drug intoxication + + + Improved
17 41 F SW 1 Cervix cancer - - + Improved
18 2 F MW 1 Pneumonia + - - Improved

∗ Body temperature, ≥38°C or <36°C; respiratory rate, >24 times/min; heart rate, >90/min; white blood cells >12,000/mm3; septic shock;

‡ Port-A catheter, temporary or permanent pacemakers, peritoneal dialysis or hemodialysis, or arterial catheters, or surgical treatment.

Abbreviations: M, male; MICU, medical intensive care unit; DM, Diabetes mellitus; F, female; MW, medical ward; SW, surgical ward; SICU, surgical intensive care unit; ARF, acute renal failure; AGE, acute gastroenteritis.

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