Comparison of E test and Disk Diffusion Test for Antibiotic Resistance Testing of Enterotoxigenic and Non- Enterotoxigenic Bacteroides fragilis Isolated From Stools

AUTHORS

Mohammad Taghi Akhi 2 , * , Reza Ghotaslou 2 , Mahnaz Shirinzadeh 2 , Tahereh Pirzadeh 2 , Mohammad Naghavi Behzad 3

2 Department of Bacteriology and Virology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, IR Iran

3 Medical Faculty, Tabriz University of Medical Science, Tabriz, IR Iran

How to Cite: Akhi M T, Ghotaslou R, Shirinzadeh M, Pirzadeh T, Naghavi Behzad M. Comparison of E test and Disk Diffusion Test for Antibiotic Resistance Testing of Enterotoxigenic and Non- Enterotoxigenic Bacteroides fragilis Isolated From Stools, Jundishapur J Microbiol. Online ahead of Print ; 6(5):-. doi: 10.5812/jjm.9800.

ARTICLE INFORMATION

Jundishapur Journal of Microbiology: 6 (5)
Published Online: June 30, 2013
Article Type: Research Article
Received: December 16, 2012
Accepted: March 10, 2013
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Abstract

Background: Enterotoxigenic Bacteroides fragilis (ETBF) are one of the most important anaerobic bacteria whichcause diarrhea in human beings. A bft gene is coded for enterotoxin production called fragilysin. Most of them have acquired resistance to antianaerobicbacteria agent like other facultative anaerobic bacteria. E test and different dilution methods are usually performed for antimicrobial susceptibility determination of B. fragilis.

Objectives: The aims of this study are to recognize ETBF by PCR method and also to evaluate efficiency thedisk diffusion method (DDM) in comparison with the E tests for antimicrobial susceptibility of B. fragilis isolates.

Materials and Methods: bft gene was detected among 157 B. fragilis isolated from patients and healthy individuals by PCR. Antimicrobial susceptibility of all isolates was determined by DDM and E tests methods.

Results: Nineteen (12.1%) B. fragilis containing bft gene from diarrheic (n = 14) and nondiarrheic (n = 5) feces were detected among 157 B. fragilis isolates. The highest resistance for ciprofloxacin, cefotaxim, cefoxitin with DDM and E test were 100%, 60%, and 65% respectively, while the lowest resistance in two methods was obtained for imipenem, piperacillin / tazobactam, and metronidazol. 100% agreement for some of antibiotics such as imipenem (P ? 0.05), and no correlation for others were observed among the antimicrobial susceptibility results obtained by the two methods (P ? 0.05).

Conclusions: The presence of bft gene in B. fragilis isolates wouldnot certainly result in diarrheaamong patients. There is not enough accordance between DDM and Swedish E tests for antimicrobial susceptibility of B. fragilis for some antibiotics, although in other cases a good agreement was observed.

Keywords

Bacteroides fragilis Antibiotic Resistance Disk Diffusion Antimicrobial Tests

© 2013, Author(s). 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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