Comparison of E test and Disk Diffusion Test for Antibiotic Resistance Testing of Enterotoxigenic and Non- Enterotoxigenic
Bacteroides fragilis Isolated From Stools
Jundishapur Journal of Microbiology: 6 (5)
June 30, 2013
Article Type: Research Article
December 16, 2012
March 10, 2013
M T, Ghotaslou
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
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.
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.
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).
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.
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