Controversial Aspects Displayed by Enterococci: Probiotics or Pathogens?

For centuries, selected Enterococci, facultative anaerobic, nonspore-forming Gram-positive bacteria belonging to the Lactic Acid Bacteria (LAB), have been widely used in the production of a variety of fermented and nonfermented food products ranging from dairy and meat products to vegetable and sea foods. Enterococci have also properties that are of technological interest in the food industry, and some strains have been used as probiotics for the maintenance of normal intestinal microbiota, stimulation of the immune system, and improvement of the nutritional value of foods and feeds in humans and animals However, following the emergence of antibiotic-resistant (AMR) enterococci and particularly of the vancomycin-resistant enterococci (VRE), these microorganisms have turned from generally recognized as safe (GRAS) for human consumption to significant pathogens threatening human health and thriving in the hospital environment. Thus, recently the trend of using enterococci as probiotics for human consumption is in debate due to the controversial aspects of these bacteria which appear to be “friends and foes

Antibiotic Resistance and Virulence Factors among Enterococci Isolated from Chourico, a Traditional Portuguese Dry Fermented Sausage

Enterococci are ubiquitous microorganisms, found as part of the normal intestinal microbiota of many animals. They can be present in food products, for example, the Portuguese dry fermented sausage chourico. Twenty enterococci were isolated from chourico in two processing units; after identification and typification by conventional-molecular methods, the isolates were screened for virulence factors and antibiotic resistance. Identification allocated all enterococci to the species Enterococcus faecalis, and PCR fingerprinting demonstrated that each isolate was specific to the processing unit and chourico from which it was recovered. Regarding the screening for virulence factors, I strain produced cytolysin and 4 were gelatinase positive, but none produced lipase. The ace gene was detected in I enterococci, ebpABC and efaA(fs). in 16 isolates each, esp in 3, fsrB in 5, gelE in 7, and cylA in I. A multiresistant phenotype was observed in 8 isolates, 6 belonging to factory A. The antibiotic resistance gene ere(B) was detected in 9 enterococci, whereas the genes tet(M), aac(6')-le-aph(2 ''), and vanA were detected in 8 isolates each. As some of the E. faecalis chourico isolates present a multiresistant profile and harbor virulence and/or resistance genes, to assess further the safety of Portuguese dry sausages, a larger number of products and processing units must by analyzed

Diversity of Staphylococcus aureus Isolates in European Wildlife

Staphylococcus aureus is a well-known colonizer and cause of infection among animals and it has been described from numerous domestic and wild animal species. The aim of the present study was to investigate the molecular epidemiology of S. aureus in a convenience sample of European wildlife and to review what previously has been observed in the subject field. 124 S. aureus isolates were collected from wildlife in Germany, Austria and Sweden; they were characterized by DNA microarray hybridization and, for isolates with novel hybridization patterns, by multilocus sequence typing (MLST). The isolates were assigned to 29 clonal complexes and singleton sequence types (CC1, CC5, CC6, CC7, CC8, CC9, CC12, CC15, CC22, CC25, CC30, CC49, CC59, CC88, CC97, CC130, CC133, CC398, ST425, CC599, CC692, CC707, ST890, CC1956, ST2425, CC2671, ST2691, CC2767 and ST2963), some of which (ST2425, ST2691, ST2963) were not described previously. Resistance rates in wildlife strains were rather low and mecA-MRSA isolates were rare (n = 6). mecC-MRSA (n = 8) were identified from a fox, a fallow deer, hares and hedgehogs. The common cattle- associated lineages CC479 and CC705 were not detected in wildlife in the present study while, in contrast, a third common cattle lineage, CC97, was found to be common among cervids. No Staphylococcus argenteus or Staphylococcus schweitzeri-like isolates were found. Systematic studies are required to monitor the possible transmission of human- and livestock- associated S. aureus/MRSA to wildlife and vice versa as well as the possible transmission, by unprotected contact to animals. The prevalence of S. aureus/MRSA in wildlife as well as its population structures in different wildlife host species warrants further investigation

Escherichia coli strains from ostriches and their sensitivity to antimicrobial substances

Ostriches are bred especially for their high-quality meat. There is a lack of knowledge concerning the ostrich’s microflora. Escherichia coli is a commensal microorganism of the poultry intestine, ostriches included. However, some strains may become pathogenic. This study was therefore undertaken to detect coliform bacteria in ostrich faeces and to test their antibiotic profile and sensitivity to enterocins. Faeces (n=54, 18 mixture samples from 3 different age groups of 140 ostriches) were sampled to isolate coliform bacteria. The counts of coliform bacteria varied from 5.69 ± 2.4 log10 CFU/g to 5.73 ± 2.4 CFU/g. Pure colonies were identified using MALDI-TOF MS mass spectrometry and confirmed by phenotypization. Seventy-one strains were allotted to the species E. coli. Sixty-four of those 71 strains caused hemolysis. They were mostly polyresistant to antibiotics. Thirty-two poly-resistant strains of E. coli were sensitive to enterocins. These strains were most sensitive to Ent 9296 (26 strains). Moreover, Ent EM41 produced by E. faecium EM41 (isolated from ostrich faeces) inhibited the growth of 20 strains, reaching activity of 100 AU/ml. Our results indicate the possibility of enterocins being used for prevention/reduction of coliforms. Of course, in vivo studies are also being processed

Characteristic and susceptibility to enterocins of enterococci in pheasants possessing virulence factor genes

With an increasing number of pheasants as gamebirds being reared each year, these species are becoming a more prominent part of the workload of many veterinary practices. Only limited information can be found concerning the microflora of common pheasants. A significant part of the obligate microflora consists of lactic acid bacteria, including enterococci. In this study, faeces were sampled from 60 pheasants aged 16-17 weeks. Enterococcal counts reached 5.48±1.9 (log10) CFU/g. Strains (17) were taxonomically classified to the genus Enterococcus using the Maldi-Tof identification system; they were allotted to the species E. hirae (58.8%), E. faecium (23.5%) and E. faecalis (17.7%) by highly probable species identification or by secure genus identification/probable species identication. Species allocation was also confirmed using conventional biochemical tests. Most strains formed β-hemolysis. Gelatinase active phenotype was found in three E. faecalis strains. Enterococci were β-glucuronidase negative, mostly trypsin negative with slight or moderate production of α-chymotrypsin. EH52b and EF42 strains possessed the highest potential for pathogenicity. Average value of lactic acid was 1.78±0.33 mmo/L. Most strains were tetracycline resistant (82.4%). Polyresistant E. faecalis strains with positive gelatinase phenotype and possessing virulence factor genes confirmed using PCR (gelE, efaAfs, ccf cob, cpd) were sensitive to enterocins (activity 1600-25 600 AU/mL)

Binding of extracellular matrix molecules by staphylococci from wild herbivores

Nine strains of staphylococci were examined for their antibiotic resistance and for binding of seven extracellular matrix (ECM) molecules (bovine mucin, porcine mucin, porcine fibronectin, bovine fibrinogen, fetuin, bovine lactoferrin and heparin) immobilized on latex beads in the particle agglutination assay. All nine strains were resistant to bacitracin, and most of them were multiresistant. Four strains displayed resistance to 5 of 13 antibiotics tested. Different binding capability between individual strains was observed. There were strains binding several ECM molecules (as S. warneri SW6 and S.. epidermidis SE14) as well as strains which bound only one (S. aureus SA 11) or no ECM molecule (S. saprophyticus SS16) of seven tested. While some ECM molecules, e.g. porcine fibronectin and heparin, were bound by most of strains, others (e.g. mucins) were bound only by I or 2 strains. Some strains bound these substrates weakly, however, other strains displayed strong binding especially of heparin and porcine fibronectin. The preincubation of bacteria for I hour at room temperature with a protein used subsequently in the PAA completely prevented the agglutination reaction, thus indicating the specificity of the assay

Lectin-like binding and antibiotic sensitivity of enterococci from wild herbivores

Fifty eight enterococcal isolates from wild herbivores were tested for their antibiotic sensitivity pattern and lectin-like binding of extracellular matrix (ECM) and serum proteins. Kanamycin resistance was very frequent; many multiresistant strains were also isolated. All isolates were sensitive to rifampicin. Resistance to gentamicin, novobiocin, and tetracycline was widely distributed in the microflora of wild herbivores breeded in zoological garden in Kosice. No autoaggregating strains were detected among these 58 enterococcal isolates. Various degrees of binding of mucins, fetuin, heparin, fibrinogen, and fibronectin were observed in individual strains. However, bovine lactoferrin binding by enterococci from deers and chamoises was either negative (0) or strongly positive (3). With regard to influence of growth media, TH agar was found to be better for the expression of lectin-like binding than blood agar, TH broth and Nutrient broth. A significant effect (P < 0.001 or P < 0.05) of proteolytic treatment was observed in six selected strains. However, there is a difference between the effect of trypsin and pronase P. Pronase treatment more effectively decreased binding of some strains (1H, 6A, EF 1111, EC 1292), while trypsin treatment decreased more binding of other enterococcal strains (EF 953 and 1E). Significant (P < 0.001) influence of metaperiodate, which cleaves the C-C bond between vicinal groups of sugars, on collagen I binding by three selected strains (1E, 1H, 6A) and bovine lactoferrin binding (by EF 1111, EC 1292, EF 953) was also observed. However, its influence was very different. In two strains (1H and EC 1292), ECM binding was decreased, while in four other strains (1E, 6A, EF 1111, EF 953) it was increased

Mode of binding of fibrinogen, fibronectin and iron-binding proteins by animal enterococci

Sixty-two animal enterococci were examined for their binding of bovine fibrinogen, porcine fibronectin, bovine lactoferrin, bovine apotransferrin and human holotransferrin in the particle agglutination assay (PAA). Individual strains expressed binding of selected glycoproteins to various degrees (0, 1, 2, 3), whereas bovine fibrinogen binding of enterococci from goats, rabbits and rodents was the strongest (3) in general. Porcine fibronectin was bound weakly (1 or 2) by enterococci from horses, dogs, poultry, rabbits and rodents, while most of the goat isolates and half of the dog feed isolates did not bind fibronectin (0). Bovine lactoferrin was bound especially by the isolates from rodents and rabbits. Bovine apotransferrin was bound very weakly (1) by only a few isolates. Human holotransferrin was bound to a greater extent than apotransferrin by some isolates from rabbits and rodents. Since multiresistant strains are preferred in our binding studies, enterococci were also examined for their antibiotic resistance pattern. Almost all investigated isolates were resistant at least to one antibiotic. However, some strains displayed resistance to five or six antibiotics of 10 antibiotics tested. In a study of the inhibitory effect of heparin, porcine mucin and hyaluronic acid, the greatest effect was observed after heparin treatment of bacterial cells. These observations, as well as the expression of heparin binding by most strains, may suggest that at least one mode of enterococcal attachment utilizes glycosaminoglycan chains present on the surface of adherent cells