Phenotypic and Molecular Antibiotic Resistance Profile ofEnterococcus faecalisandEnterococcus faeciumIsolated from Different Traditional Fermented Foods

Abstract

A collection of 55 enterococci (41 Enterococcus faecium and 14 E. faecalis strains) isolated from various traditional fermented foodstuffs of both animal and vegetable origins, and water was evaluated for resistance against 15 antibiotics. Lower incidence of resistance was observed with gentamicin, ampicillin, penicillin and teicoplanin. However, a high incidence of antibiotic resistance was detected for rifampicin (12 out of 14 of isolates), ciprofloxacin (9/14), and quinupristin/dalfopristin (8/14) in E. faecalis strains. Enterococcus faecium isolates were resistant to rifampicin (25/41), ciprofloxacin (23/41), erythromycin (18/41), levofloxacin (16/41), and nitrofurantoin (15/41). One Enterococcus faecalis and two E. faecium strains were resistant to vancomycin (MIC>16 μg/mL). Among 55 isolates, 27 (19 E. faecium and eight E. faecalis) were resistant to at least three antibiotics. High level of multidrug resistance to clinically important antibiotics was detected in E. faecalis strains (57% of E. faecalis versus 46% of E. faecium), which showed resistance to six to seven antibiotics, especially those isolated from foods of animal origin. So, it is necessary to re-evaluate the use of therapeutic antibiotics in stock farms at both regional and international levels due to the high number of multiple resistant (MR) bacteria. Fifty-six MR E. faecalis and E. faecium strains selected from this and previous studies (Valenzuela et al., 2008, 2010) were screened by polymerase chain reaction for antibiotic resistance genes, revealing the presence of tet(L), tet(M), ermB, cat, efrA, efrB, mphA, or msrA/B genes. The ABC Multidrug Efflux Pump EfrAB was detected in 96% of E. faecalis strains and also in 13% of E. faecium strains; this is the first report describing EfrAB in this enterococcal species. The efflux pump-associated msrA/B gene was detected in 66.66% of E. faecium strains, but not in E. faecalis strains.

Horizontal transfer of antibiotic resistance from Enterococcus faecium of fermented meat origin to clinical isolates of E. faecium and Enterococcus faecalis

“…Therefore, the food chain is considered to be one of the main routes for transmission of antibiotic resistance among the human microbiota (Rizzotti et al, 2009). Antibiotic resistant enterococci are common in foods of animal origin (Aslam et al, 2012;Jahan et al, 2013;Sánchez Valenzuela et al, 2013). These contaminating microorganisms are able to grow and colonize during sausage fermentation because they are tolerant of ripening conditions and are selected for in the process.…”

Food and human gut as reservoirs of transferable antibiotic resistance encoding genes

“…The ESBLs of the RAHN family have been described in R. aquatilis strains that were isolated from raw fruits and vegetables (Ruimy et al, 2010a,b). Traditionally fermented foods of animal and vegetable origins may also contain AR bacteria, such as Enterococcus faecium and Enterococcus faecalis , both of which exhibit a high incidence of resistance to rifampicin, ciprofloxacin, and quinupristin/dalfopristin, and surprisingly, vancomycin (Sánchez et al, 2013). Finally, the recent significant outbreak of hemolytic uremic syndrome in Germany in 2011 was found to be due to a CTX-M-15 ESBL E. coli clone likely originating from fenugreek seeds imported from Egypt (Buchholz et al, 2011; Rasko et al, 2011; Weiser et al, 2013).…”

Safety of the Surrogate Microorganism Enterococcus faecium NRRL B-2354 for Use in Thermal Process Validation

“…Resistance of E. faecium to either vancomycin or ampicillin severely limits treatment options for enterococcal infections. While strain NRRL B-2354 exhibited an intermediate level of resistance to erythromycin, this trait is common among other food-associated E. faecium (71).…”