Pojavnost proti antibiotikom odpornih sevov bakterije Escherichia coli v površinskih vodah : magistrsko delo

Novak, Maja (author), Godič Torkar, Karmen (mentor), Oder, Martina (reviewer)

Uvod: Hitro širjenje proti antibiotikom odpornih bakterij predstavlja resen javnozdravstveni problem. Odporne bakterije in geni za odpornost proti antibiotikom niso omejeni le na klinično okolje, temveč so vse bolj razširjeni pri bakterijskih populacijah v naravnem okolju. Površinske vode, predvsem jezera in reke zaradi njihove potencialne vloge pri ohranjanju in razširjanju protimikrobne odpornosti iz okolja na človeške ali živalske patogene, predstavljajo posebno skrb. Namen: Pri sevih bakterije Escherichia coli, osamljenih iz površinskih vod, smo želeli ugotoviti odpornost proti antibiotikom in prisotnost nukleotidnih zaporedij za posamezne tipe ß-laktamaz. Metode dela: Pri sevih bakterije Escherichia coli, ki so predvidoma tvorili ß-laktamaze razširjenega spektra, smo ugotavljali njihovo odpornost proti izbranim ß-laktamskim, aminoglikozidnim in tetraciklinskim antibiotikom z difuzijsko metodo z diski. Prisotnost encimov ESßL, karbapenemaz in ß-laktamaz AmpC smo določali fenotipsko z metodo s kombiniranimi diski in metodo s približanimi diski ter genotipsko z verižno reakcijo s polimerazo. Rezultati: Izmed 192 testiranih sevov bakterije Escherichia coli jih je 89 (46,35 %) poraslo na selektivnem gojišču za ESßL. Od teh 89 sevov, ki so predvidoma tvorili ß-laktamaze razširjenega spektra, jih je bilo 73 % odpornih proti vsaj enemu izmed 11 testiranih antibiotikov. V najvišjem deležu so bili odporni proti antibiotikom kanamicinu (41,57 %), amoksicilinu s klavulansko kislino (29,21 %) in cefotaksimu (16,85 %). Z metodo s kombiniranimi diski smo ugotovili prisotnost encimov ß-laktamaz le pri nekaterih sevih, medtem ko smo z verižno reakcijo s polimerazo dokazali ESßL pri 93,26 %, karbapenemaze pri 65,17 % in ß-laktamaze AmpC pri 34,83 % sevov bakterije Escherichia coli. Pri ugotavljanju korelacije med prisotnostjo genov za virulentne dejavnike in genov za odpornost proti antibiotikom nismo ugotovili pomembne povezave. Razprava in zaključek: Dokazali smo, da Podpeško jezero in Rakiško jezero predstavljata pomemben rezervoar proti antibiotikom odpornih sevov bakterije Escherichia coli, ki imajo prisotna nukleotidna zaporedja za encime ESßL, karbapenemaze in ß-laktamaze AmpC. Številni potencialno patogeni sevi imajo prisotne gene za odpornost proti antibiotikom, kar ne predstavlja samo potencialnega tveganja za zdravje ljudi ob izpostavljenosti, temveč pripomore k razširjenosti protimikrobne odpornosti v okolju, kar povzroča vse večje izzive pri zdravljenju bakterijskih okužb.

• Language: Slovenian
• Keywords: magistrska dela, sanitarno inženirstvo, protimikrobna odpornost, površinske vode, bakterija Escherichia coli, ß-laktamaze, karbapenemaze, ß-laktamaze AmpC, ESßL
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [M. Novak]
• Year: 2023
• Number of pages: 81 str., [3] str. pril.
• PID: 20.500.12556/RUL-148738
• UDC: 614
• COBISS.SI-ID: 162810627
• Publication date in RUL: 31.08.2023

Secondary language

• Language: English
• Title: Occurrence of antibiotic resistant Escherichia coli in surface waters : master thesis

Abstract

Introduction: The rapid spread of antibiotic-resistant bacteria is a serious public health problem. Resistant bacteria and antibiotic resistance genes are not only limited to the clinical environment but are increasingly widespread among bacterial populations in the natural environment. Surface waters, particularly lakes and rivers, represent a particular concern due to their potential role in the preservation and dissemination of antimicrobial resistance from the environment to human or animal pathogens. Purpose: We aimed to determine the antibiotic resistance and the presence of nucleotide sequences for individual types of ß-lactamases in strains of Escherichia coli, isolated from surface waters. Methods: In Escherichia coli strains that presumably produced extended-spectrum ß-lactamases, we wanted to determine their resistance to selected ß-lactam, aminoglycoside and tetracycline antibiotics using the disc diffusion method. We used combined disc method and disc approximation test to phenotypically determine the presence of ESßLs, carbapenemases and ß-lactamases AmpC in Escherichia coli strains. For genotypical determination of those enzymes in Escherichia coli strains, we used a polymerase chain reaction. Results: From the 192 tested Escherichia coli strains, 89 (46,35 %) grew on the ESßL selective medium. Of these 89 strains, predicted to produce extended-spectrum ß-lactamases, 73 % were resistant to at least one of the 11 tested antibiotics. The highest resistance rates were observed against kanamycin (41,57 %), amoxicillin with clavulanic acid (29,21 %), and cefotaxime (16,85 %). Using the combined disc method, we found the presence of ß-lactamases in only some Escherichia coli strains, while the polymerase chain reaction proved the presence of ESßLs in 93,26 %, carbapenemases in 65,17 % and ß-lactamases AmpC in 34,83 % of the strains of Escherichia coli. We did not find a significant correlation between the presence of virulence factor genes and antibiotic resistance genes. Discussion and conclusion: We demonstrated that Podpeško lake and Rakiško lake represent important reservoirs of antibiotic resistant strains of Escherichia coli harboring nucleotide sequences for ESßLs, carbapenemases and ß-lactamases AmpC. Many potentially pathogenic strains carry antibiotic resistance genes, which pose not only a potential risk to human health upon exposure, but also contribute to the spread of antimicrobial resistance in the environment, leading to increasing challenges in the treatment of bacterial infections.

• Keywords: master's theses, sanitary engineering, antimicrobial resistance, surface waters, Escherichia coli, ß-lactamases, carbapenemases, ß-lactamases AmpC, ESßL