Occurrence and antibiotic resistance of enterotoxigenic Staphylococcus aureus in raw ovine and caprine milk in Greece

International audienceAbstractOvine (n = 140) and caprine (n = 35) raw bulk tank milk samples from farms in central Greece were examined for the occurrence of enterotoxigenic Staphylococcus aureus. The S. aureus isolates were screened for staphylococcal enterotoxin (SE) production, the presence of enterotoxin genes, antibiotic resistance (AR), and methicillin resistance. S. aureus was isolated from 24.3% and 31.4% of ovine and caprine milk samples, respectively. Among the S. aureus isolates of ovine milk (n = 34) and caprine (n = 11) milk, the enterotoxigenic (SEA-SED) isolates were 21 (61.8%) and 7 (63.6%) for the ovine and caprine milk, respectively. Most toxigenic isolates harbored more than one toxin gene and a total of 11 distinct toxinotypes were detected. The most frequent toxin-gene combinations were “sec, tst” (8 isolates), “seb, seg, sei, tst” (4), “seb, seg, sei” (3), and “seb” (3). Six isolates displayed multiple AR towards up to five antimicrobials. Among ovine milk isolates, the highest resistance frequency was observed towards erythromycin (11.8% of the isolates) and tetracycline (8.8%). Among caprine milk isolates, the most frequent resistance was observed towards erythromycin (18.2%). One methicillin-resistant S. aureus (MRSA) isolate was detected in an ovine milk sample and belonged to spa type t4038. This spa type has been isolated for the first time in Greece and, to our knowledge, has not been previously reported among MRSA isolates from raw milk or dairy products worldwide

The antimicrobial effect of herbs essential oils and nisin added in beef meat

The antimicrobial effect of oregano, thyme, rosemary essential oils and their mixture, nisin at 500 or 1000 IU/g, and their combinations, on L. monocytogenes, S. aureus, E. coli O157:H7 and Salmonella in tryptic soy broth (TSB) during incubation at 37 o C for 32 h was weak at the concentration of 0.3%, but high at the levels of 0.6 and 0.9%. Due to strong antimicrobial activity presented by the essential oils at 0.6 and 0.9% in TSB, the synergistic activity against the tested pathogens was only evident for the combinations with nisin at 500 or 1000 IU/g and the essential oils at 0.3%. Sensory evaluation revealed that the organoleptic properties of minced beef meat treated with oregano, thyme, rosemary essential oils and their mixture at the supplementation levels of 0.3 and 0.6% and also oregano at 0.9% were acceptable by the panelists. In contrast, the organoleptic properties of thyme, rosemary essential oils and the mixture of all the essential oils at 0.9% were not acceptable by the panelists. The antibacterial efficacy of all the essential oils at 0.3% in minced beef meat was not examined, since pertinent results in TSB showed a weak antibacterial activity against the examined pathogens, whereas the addition of thyme, rosemary and the mixture of the essential oils at 0.9% were also not examined because organoleptic study showed unacceptable organoleptic properties in minced meat. The antimicrobial effect against L. monocytogenes, S. aureus, E. coli O157:H7 and Salmonella of the essential oils, nisin and their combinations were studied in minced beef meat during refrigerated storage at 4 or 10 οC 12 days and were studied in the following treatment groups: · No addition of essential oils, nisin or their combinations · Addition of oregano essential oil at 0.6 or 0.9%, thyme essential oil at 0.6%, rosemary essential oil at 0.6% or their mixture at 0.6%, · Addition of nisin at 500 or 1000 IU/g and · Addition of combinations of oregano essential oil at 0.6 or 0.9%, thyme essential oil at 0.6%, rosemary essential oil at 0.6% or their mixture at 0.6% with nisin at 500 or 1000 IU/g,Η αντιμικροβιακή δράση της προσθήκης των αιθέριων ελαίων ρίγανης, θυμαριού, δενδρολίβανου και μίγματός τους κατά των παθογόνων L. monocytogenes, S. aureus, E. coli O157:H7 και Salmonella σε θρεπτικό ζωμό στους 37 o C για 32 ώρες ήταν ασθενής σε συγκέντρωση 0.3%, ενώ ήταν ισχυρή στις συγκεντρώσεις 0.6 και 0.9%. Η συνεργός αντιμικροβιακή δράση κατά των εξετασθέντων παθογόνων της προσθήκης των συνδυασμών των αιθέριων ελαίων με τη νισίνη (500 ή 1000 IU/ml) ήταν εμφανής κατά κύριο λόγο στη συγκέντρωση 0.3% των αιθέριων ελαίων. Τα εξετασθέντα οργανοληπτικά χαρακτηριστικά (οσμή, γεύση και συνολική αποδοχή) της προσθήκης των αιθέριων ελαίων ρίγανης, θυμαριού, δενδρολίβανου και μίγματός τους (σε ίσες αναλογίες) σε συγκεντρώσεις 0.3 και 0.6% και της ρίγανης 0.9% παρέμειναν αποδεκτά από τους δοκιμαστές καθ’ όλη τη διάρκεια της συντήρησης στην ψύξη, σε αντίθεση με εκείνα της προσθήκης των αιθέριων ελαίων θυμαριού, δενδρολίβανου και του μίγματος των αιθέριων ελαίων σε συγκεντρώσεις 0.9% που δεν ήταν αποδεκτά. Για όλα τα αιθέρια έλαια οι συγκεντρώσεις 0.3% δεν επιλέχθηκαν να μελετηθούν στο μυττωτό βοείου κρέατος, γιατί παρουσίασαν ασθενή αντιμικροβιακή δράση στο TSB, ενώ αντίστοιχα για τα αιθέρια έλαια θυμαριού, δενδρολίβανου και του μίγματος των αιθέριων ελαίων οι συγκεντρώσεις 0.9% δεν επιλέχθηκαν, γιατί εμφάνισαν οργανοληπτικά χαρακτηριστικά που δεν ήταν αποδεκτά στον οργανοληπτικό έλεγχο. Η μελέτη της αντιμικροβιακής δράσης της προσθήκης των αιθέριων ελαίων, της νισίνης και του συνδυασμού τους σε «στείρο» μυττωτό βόειου κρέατος κατά στελεχών των παθογόνων L. monocytogenes, S. aureus, E. coli O157:H7 και Salmonella κατά τη συντήρησή του στους 4 και 10 oC για 12 ημέρες, περιελάμβανε τις εξής ομάδες: · Απουσία αιθέριου ελαίου (μάρτυρες) · της προσθήκης των αιθέριων ελαίων ρίγανης (0.6 και 0.9%), θυμαριού (0.6%), δενδρολίβανου (0.6%) και μίγματός τους (0.6 %) · της προσθήκης της νισίνης σε συγκεντρώσεις 500 και 1000 IU/g και · της προσθήκης των συνδυασμών των αιθέριων ελαίων ρίγανης (0.6 και 0.9%), θυμαριού (0.6%), δενδρολίβανου (0.6%) και μίγματός τους (0.6 %) με τη νισίνη (500 και 1000 IU/g

Q fever and prevalence of Coxiella burnetii in milk

Background Q fever is a zoonosis caused by Coxiella burnetii. In humans, although it has been predominantly considered an occupational hazard, in the last decades, Q fever outbreaks have also been reported in various countries, indicating its importance as an emerging public health threat. Domestic ruminants are considered as the most important sources of human infection. In fact, both symptomatic and asymptomatic infected ruminants shed the bacterium into the environment with birth products, but also in urine, faeces, vaginal mucus and milk. Q fever in humans is mainly asymptomatic, but it also may manifest itself as an acute or chronic disease with long-term sequelae. Inhalation of infectious aerosols usually causes the disease in humans, but the presence of C. burnetii in raw milk raises concern over the role of milk as a source of infection. Scope and approach In this review data on Q fever in humans are summarized and the possible transmission of C. burnetii to humans by consumption of unpasteurized milk is discussed. In addition, an overview of the published data on the prevalence studies of C. burnetii in raw milk in various countries is provided. Key findings and conclusions Recent surveys conducted in many countries have revealed that the prevalence of C. burnetii in raw milk can vary over a wide range from 0% to as high as 95%. Based on recent survey data, the risk of C. burnetii infection by consuming unpasteurized milk and raw milk products cannot be considered negligible. © 2017 Elsevier Lt