Antimicrobial Resistance in Recent Fecal Enterococci from Healthy Volunteers and Food Handlers in Spain: Genes and Phenotypes

Abstract

Susceptibility patterns to 15 different antibiotics and the presence of resistance genes were evaluated in recent fecal Enterococcus isolates recovered from 42 healthy volunteers (HV) and 43 food-handlers (FH). A total of 142 Enterococcus faecalis, 74 Enterococcus faecium, and 23 Enterococcus spp. with different antibiotic susceptibility patterns were studied. A higher percentage of resistance for moxifloxacin, erythromycin, glycopeptides and high-level resistance (HLR) to gentamicin were observed in the FH group. Ampicillin- or linezolid-resistant isolates were not recovered in any of the groups. The tet(M) gene was found in 96% and in 85% of tetracycline-resistant isolates from HV and FH, respectively. HLR-kanamycin was mediated by aph(3')-IIIa, or aac(6')-aph(2"), or both genes in all isolates from HV group and in 86% from FH group. The aac(6')-aph(2") gene was found in all HLR-gentamicin isolates. Ninety-one percent of HV and 71% of FH erythromycin-resistant isolates harbored the erm(B) gene (erythromycin MIC range of 8-128 microg/ml), whereas erm(A), erm(C), or mef(A) genes were not detected. Coexistence of erm(B), aph(3')-IIIa, and tet(M) genes was observed in 17% of the isolates of both groups. The HLR-gentamicin isolates presented unrelated PFGE patterns while 2 out of 3 vanA E. faecium isolates showed an indistinguishable SmaI-pulsed-field gel electrophoresis (PFGE) pattern. This study shows that despite 4 years of official banning of antibiotic growth promoters in animals, enterococci isolated from FH are more resistant than those from HV. This suggests the permanence of resistant clones or transferable resistance elements in farms and a possible exchange between food products and humans, or eventually the long-term permanence of certain clones in the FH intestinal tract.

Detection of antibiotic resistant E. coli and Enterococcus spp. in stool of healthy growing children in Portugal

“…This fact could indicate that vancomycin-resistant enterococci could be present within the faecal enterococcal population of humans but in a low proportion with respect to the vancomycin-susceptible ones, and thus could not be detected when non-supplemented-plates were used for bacterial isolation. Our results are in disagreement with those obtained by our group and by others, in which ampicillinresistant enterococci were not recovered in healthy humans [20,39]. Nine isolates show high-level-resistance (HLR) for streptomycin and kanamycin and 4 HLR for gentamicin (3 E. faecalis and one E. durans).…”

“…Percentages (%) and number of E. coli isolates E. faecium (n = 53) coccal species detected in human infections [36 -38] and in healthy humans [39]. However, these results are similar to reported by our group in healthy humans and pets (dogs and cats) [20].…”

“…The tet(M) or tet(L) genes (alone or associated), were demonstrated in all but three of the tetracycline-resistant isolates; the both genes were detected in 19 isolates, 6 presented only the tet(M) gene and 1 showed only the tet(L) gene. As previously reported by our group and by others the combination tet(M) + tet(L) was the more frequently found in enterococci recovered from humans [20] with tet(M) being the most frequent tetracycline resistant gene reported in enterococci [20,39]. The catA gene, encoding a chloramphenicol acetyltransferase, was found in 3 of 10 isolates chloramphenicol-resistant isolates.…”

Dogs Are a Reservoir of Ampicillin-Resistant Enterococcus faecium Lineages Associated with Human Infections

“…On the contrary, only 1 of the 18 healthy humans tested was found to be positive for E. faecium. One previous study failed to detect AREF in healthy humans despite the use of selective isolation media (9). However, the human carriage rate observed needs to be confirmed on a larger scale, since the low community prevalences of AREF among healthy people (0 to 6%) reported in other studies (1, 2, 11, 23) might be influenced by the use of nonselective isolation methods.…”

Prevalencia de Enterococos resistentes a antibióticos en aguas servidas en el norte de Chile

“…Los antibióticos aminoglicósidos se asocian con antibióticos ß-lactámicos para obtener efectos sinérgicos frente a infecciones por enterococos, pero éstos pueden usarse solamente cuando la resistencia es de bajo nivel. Ha sido descrito que la resistencia a los antibióticos aminoglicósidos parece estar mediada por la presencia de enzimas inactivantes de aminoglicósidos [36][37][38] .…”