In vitro activity of a mixture of mustard oils (isothiocyanates) against antimicrobial and multidrug-resistant bacteria

Abstract number: P614

Conrad A., Bauer D., Nobis T., Richter H., Engels I., Jonas D., Frank U.

Objectives: A herbal native preparation containing Tropaeoli majoris herba (nasturtium = N) and Armoraciae rusticanae radix (horseradish = H; Angocin® Anti-Infekt N, Repha GmbH, Germany) may be used for treatment of upper respiratory (URTI) and urinary tract infections (UTI). The preparation's antimicrobial efficacy is based on mustard oils (isothiocyanates = ITC), which are cleaved from glucosinolates after oral intake: benzyl-ITC from N, and allyl and phenylethyl-ITC from H. The objective was to assess the antimicrobial activity of a mixture of ITC against antimicrobial and multi-drug resistant bacteria.

Methods: Agar-dilution susceptibility testing was performed. ITC were mixed according to the proportion within the preparation by adding 50% (v/v) benzyl-ITC, 37.9% allyl-ITC, and 12.1% phenylethyl-ITC (all Fluka, Germany). The oil-mixture was dissolved in tryptic soy broth containing 8% Tween 80. Serial dilutions were performed and the mixture was added to Mueller Hinton agar just before casting in order to obtain concentrations ranging from 1% to 0.001%. Bacterial species were tested by use of a multi-point-inoculator (48 isolates in duplicates). Different bacterial species originated from a German surveillance project on antimicrobial resistance and included ESBL-producing Escherichia coli (n = 49), ciprofloxacin resistant E. coli (53), ESBL-producing Klebsiella pneumoniae (49), imipenem, ceftazidime and multi-drug resistant Pseudomonas aeruginosa (50), penicillin and macrolide resistant and intermediate resistant Streptococcus pneumoniae (43), meticillin resistant Staphylococcus aureus (48), vancomycin resistant Enterococcus faecium (50). After incubation for 24h at 37°C, minimum inhibitory concentrations (MIC) were assessed, followed by subculturing to determine minimum bactericidal concentrations (MBC).

Results: MIC90 (% v/v) / MBC90 (% v/v): ESBL-producing E. coli 0.015/0.125, ciprofloxacin resistant E. coli 0.03/0.25, ESBL-producing K. pneumoniae 0.125/0.125, imipenem, ceftazidime and multi-drug resistant P. aeruginosa 0.03/0.06, penicillin and macrolide resistant and intermediate resistant S. pneumoniae 0.015/0.03, meticillin resistant S. aureus 0.004/0.5, vancomycin resistant E. faecium 0.015/>1.

Conclusion: The mixture of ITC displays broad activitiy against various antimicrobial and multi-drug resistant bacteria.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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