Odpornost proti antibiotikom in virulenčni dejavniki enterokokov pri živalih in v živilih živalskega izvora

Golob, Majda (author), Zdovc, Irena (mentor), Pate, Mateja (comentor)

Enterokoki so ubikvitarni mikroorganizmi, indikatorji fekalne kontaminacije in del normalne črevesne mikrobiote, ki lahko povzročajo resne okužbe ljudi in živali, pomembni so tudi kot povzročitelji okužb, povezanih z zdravstvom. Namen naše raziskave je bil pridobiti podatke o odpornosti in virulenčnih dejavnikih pri enterokokih, izoliranih iz vzorcev rejnih in ljubiteljskih živali ter živil živalskega izvora ter jih primerjati z enterokoki, izoliranimi iz kliničnih vzorcev ljudi. Analizirali smo 854 enterokokov 16 različnih vrst. Z mikrodilucijsko metodo določanja minimalne inhibitorne koncentracije smo ugotavljali odpornost enterokokov proti 12 antibiotikom. Z metodo verižne reakcije s polimerazo smo ugotavljali prisotnost sedmih genov za virulenčne dejavnike: ace, asa1, cylA, efaA, esp, gelE in hyl. Največji delež odpornosti smo ugotovili proti tetraciklinu, eritromicinu in ciprofloksacinu. Občutljivost enterokokov za skupino kritično pomembnih antibiotikov, ki se uporabljajo za zdravljenje okužb ljudi, je bila večinoma dobro ohranjena. Največji delež odpornosti smo ugotovili pri enterokokih iz kliničnih vzorcev ljudi in živali, mesa piščancev in perutninske klavnice, najmanjšega pa pri enterokokih iz govejega mesa. Pri živalih smo izolirali tudi 10 proti vankomicinu odpornih enterokokov in 59 enterokokov, ki so bili odporni proti visokim koncentracijam aminoglikozidov. Največ genov za virulenčne dejavnike smo ugotovili pri izolatih vrste Enterococcus faecalis, od tega najpogosteje gene efaA, gelE in ace. Izolati vrste Enterococcus faecium so bili najpogosteje nosilci genov esp in hyl. Skupaj smo pri vseh testiranih enterokokih določili 28 različnih virulenčnih tipov. Na osnovi predhodno ugotovljenih genov za površinske adhezine (ace, asa1 in esp) smo 92 izbranih izolatov testirali glede sposobnosti filmotvornosti na mikrotitrskih ploščicah. Pri izolatih s kombinacijo vseh treh genov smo ugotovili močno značilno povezavo s filmotvornostjo, vendar pa pri primerjavi posameznih genov te povezave nismo ugotovili za gen asa1. Rezultati naše raziskave v splošnem ne kažejo na večjo nevarnost zaradi neposrednega prenosa odpornih ali bolj patogenih enterokokov z živali na ljudi, nedvomno pa predstavljajo zelo pomemben rezervoar genov za odpornost in številne virulenčne dejavnike. Raziskava predstavlja pomemben doprinos k oceni tveganja za prenos odpornih enterokokov ter virulenčnih determinant iz živali na ljudi, bodisi preko prehranske verige ali pa preko ljubiteljskih živali.

• Language: Slovenian
• Keywords: Enterococcus spp, klinični vzorci ljudi in živali, rejne živali, živila živalskega izvora, školjke, odpornost proti protimikrobnim zdravilom, virulenčni dejavniki, filmotvornost
• Work type: Doctoral dissertation
• Organization: VF - Veterinary Faculty
• Year: 2021
• PID: 20.500.12556/RUL-128474
• Publication date in RUL: 15.07.2021

Secondary language

• Language: English
• Title: Antimicrobial resistance and virulence factors in enterococci from animals and food of animal origin

Abstract

Enterococci are ubiquitous microorganisms, indicators of faecal contamination and a part of normal intestinal microbiota, which are also capable of causing serious infections in humans and animals. They are also an important cause of nosocomial infections. The aim of the present study was to collect data about the prevalence of antimicrobial resistance and virulence genes in enterococci isolated from pet animals, livestock and food of animal origin in order to compare them with enterococci isolated from human clinical samples. A total of 854 Enterococcus isolates belonging to 16 species were analysed. Broth microdilution method was used to determine the minimum inhibitory concentrations of 12 antimicrobials. Polymerase chain reaction was used to detect the presence of seven virulence-associated genes (ace, asa1, cylA, efaA, esp, gelE and hyl). The highest resistance rate was found for tetracycline, erythromycin and ciprofloxacin. The susceptibility of enterococci for the critically important antimicrobials for human medicine was generally well conserved. The highest resistance rate was detected in isolates from human and animal clinical samples, broiler meat and poultry slaughterhouse, whereas the smallest proportion of resistance was observed in isolates from beef. In animals, 10 vancomycin-resistant isolates and 59 isolates with high-level aminoglycoside resistance were discovered. The highest occurrence of virulence-associated genes was observed in Enterococcus faecalis isolates, most commonly genes efaA, gelE and ace. Enterococcus faecium isolates most frequently harboured genes esp and hyl. In total, 28 distinct virulence types were identified. According to the previously detected genes encoding surface adhesins (ace, asa1 and esp), 92 isolates were selected to determine their biofilm forming ability on microtiter plates. The presence of all three aforementioned genes was significantly associated with their biofilm forming ability, as well as the sole presence of ace or esp gene, respectively, whereas no significant association was identified for asa1 gene. The results of the present study indicate a risk for direct transmission of resistant or highly virulent enterococci from animals to humans. In addition, enterococci represent an important reservoir of resistance and virulence-associated genes. The study is an important contribution to risk assessment regarding the transmission of resistant and virulent enterococci from animals to humans, either via food chain or pet animals.

• Keywords: Enterococcus spp, human and animal clinical samples, livestock, food of animal origin, mussels, antimicrobial resistance, virulence factors, biofilm forming ability