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Submitted: 04 Jan 2016
Revised: 31 Jan 2016
Accepted: 19 Feb 2016
First published online: 16 Mar 2016
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Avicenna J Clin Microbiol Infect. 2016;3(2): e36033.
doi: 10.17795/ajcmi-36033
  Abstract View: 449
  PDF Download: 181

Research Article

Detection of hblA and bal Genes in Bacillus cereus Isolates From Cheese Samples Using the Polymerase Chain Reaction

Shabnam Molayi Kohneshahri 1, Zahra Deilami Khiabani 1, Abdolmajid Ghasemian 2, Reza Shapoury 1, Javid Taghinejad 3, Majid Eslami 2, Siamak Heidarzadeh 4 *

1 Department of Microbiology, Zanjan Branch, Faculty of Basic and Medical Sciences, Islamic Azad University, Zanjan, IR Iran
2 Microbiology Department, Faculty of Medicine, AJA University of Medical Sciences, Tehran, IR Iran
3 Department of Microbiology, Malekan Branch, Islamic Azad University, Malekan, IR Iran
4 Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran
Corresponding author: Siamak Heidarzadeh, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Qods St, Poursina St, Tehran, IR Iran. Tel: +98-2188994823 Email: heidarzadehsiamak@gmail.com

Abstract

Background: Bacillus cereus is a Gram-positive spore-forming bacterium, which causes food poisoning. Spores enable the persistence of B. cereus in the environment, and B. cereus strains can tolerate adverse environmental conditions, such as temperature and insufficient nutrients. B. cereus causes food poisoning via the production of two enterotoxins. Most isolates produce toxins leading to diarrhea (enterotoxins) and vomiting (emetic forms). Diarrhea is caused by the production of three different heat-labile enterotoxins: HBL, NHE, and cytotoxin K. A heat-stable toxin, cereulide, is responsible for emesis.

Objectives: This study aimed to detect enterotoxigenic B. cereus isolates in cheese samples using the polymerase chain reaction (PCR).

Materials and Methods: Two-hundred pasteurized (n = 100) and nonpasteurized (n = 100) cheese samples were collected. The initial isolation was performed on PEMBA specific medium. Antibiotic susceptibility testing was performed using several antibiotic disks, according to the guidelines of the Clinical Laboratory and Standards Institute. Specific primers amplifying the hblA enterotoxinencoding gene and bal hemolysin-encoding gene were used for the molecular detection of the toxins.

Results: Ten samples were positive for the presence of B. cereus, with both Gram staining and biochemical reactions. All the isolates were resistant to penicillin and ampicillin but susceptible to vancomycin, erythromycin, and ciprofloxacin. Six and three isolates were resistant to tetracycline and trimethoprim-sulfamethoxazole, respectively. The hblA and bal genes were amplified in all the B. cereus isolates.

Conclusions: The prevalence of B. cereus among the cheese samples was low. All the isolates were positive for genes encoding the hblA enterotoxin and bal toxin.

Keywords: Hemolysin, Enterotoxin Gene, PCR, Bacillus cereus
Copyright © 2016, Hamadan University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.
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