Pojavnost odpornosti proti antibiotikom pri bakterijah fekalnega izvora v različnih fazah čiščenja odpadne vode v dveh komunalnih čistilnih napravah : magistrsko delo

Štuhec, Aneja (author), Godič Torkar, Karmen (mentor), Griessler Bulc, Tjaša (reviewer)

Uvod: Odpornost mikroorganizmov proti antibiotikom je zaradi njihove prekomerne uporabe v humani medicini in veterini postala globalni problem. Odpadne vode iz različnih virov pogosto vsebujejo visoke koncentracije ostankov antibiotikov in tudi proti njim odpornih mikroorganizmov. Namen: Namen dela je bil ugotoviti koncentracijo bakterij iz družine Enterobacteriaceae in rodu Enterococcus v posameznih fazah čiščenja komunalne odpadne vode v dveh čistilnih napravah ter ugotoviti odpornost osamljenih bakterij proti najpogosteje uporabljenim antibiotikom. Pri sevih iz družine Enterobacteriaceae smo preučevali tvorbo β-laktamaz razširjenega spektra in karbapenemaz, pri enterokokih pa prisotnost proti vankomicinu odpornih sevov. Metode dela: V magistrskem delu smo v vzorcih odpadne vode, odvzetih v različnih fazah čiščenja v dveh komunalnih čistilnih napravah, ugotavljali koncentracijo bakterij z metodo štetja kolonij na gojiščih in osamljene bakterijske seve iz rodu Enterococcus ter družine Enterobacteriaceae identificirali z biokemijskimi metodami. Za ugotavljanje odpornosti sevov proti antibiotikom smo uporabili difuzijsko metodo z diski po Kirby-Bauerju, metodo s kombiniranimi in metodo s približanimi diski. Rezultati: Iz vseh odvzetih vzorcev smo osamili 123 sevov družine Enterobacteriaceae in 79 sevov rodu Enterococcus. Največ sevov je pripadalo rodovom Escherichia spp. (30,1 %), Kluyvera spp. (17,9 %) in Salmonella spp. (11,4 %), izmed enterokokov pa vrstama E. faecalis in E. faecium. Osamljeni sevi enterobakterij iz obeh komunalnih čistilnih naprav so bili najpogosteje odporni proti azitromicinu (81,1 %), ampicilinu (77,9 %) in cefpodoksimu (69,3 %), medtem ko je bilo proti vankomicinu odpornih 3,8 % sevov enterokokov. Indeks večkratne odpornosti proti antibiotikom je presegel 0,2 pri 109 sevih (88,6 %). Največji delež (51,4 %) odpornih enterobakterij smo ugotovili v vzorcih iz aeracijskih bazenov. Razprava in zaključek: Na podlagi dobljenega indeksa večkratne odpornosti proti antibiotikom smo ugotovili, da komunalne čistilne naprave nudijo okolje, kjer so bakterije izpostavljene visokemu tveganju za razvoj odpornosti. Izvor in sestava odpadne vode ter tehnologije čiščenja odpadne vode so dejavniki, od katerih je odvisno razširjanje odpornosti proti protimikrobnim snovem med mikroorganizmi v naravnem okolju in vplivu na ostale žive organizme, vključno na človeka.

• Language: Slovenian
• Keywords: magistrska dela, sanitarno inženirstvo, antibiotiki, bakterije, Enterobacteriaceae, Enterococcus, čistilna naprava, odpornost proti antibiotikom
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [A. Štuhec]
• Year: 2026
• Number of pages: XIV, 72 str., [24] str. pril.
• PID: 20.500.12556/RUL-186106
• UDC: 614
• COBISS.SI-ID: 289050115
• Publication date in RUL: 27.08.2026

Secondary language

• Language: English
• Title: Occurrence of antibiotic resistance in bacteria of faecal origin at different stages of wastewater treatment in two municipal wastewater treatment plants : master thesis

Abstract

Introduction: Antimicrobial resistance has become a global problem due to the excessive use of antimicrobials in human and veterinary medicine. Wastewater from various sources often contains high levels of antimicrobial residues and resistant microorganisms. Purpose: The aim of this study was to determine the concentration of bacteria from the family Enterobacteriaceae and the genus Enterococcus in individual treatment phases at two wastewater treatment plants and to determine the resistance of isolated bacteria to the most commonly used antibiotics. The production of extended-spectrum β-lactamases and carbapenemases in enterobacterial strains, as well as the presence of vancomycin-resistant enterococci, was also investigated. Methods: The bacterial concentration in wastewater samples collected at different treatment phases in two wastewater treatment plants was determined using the plate count technique. Isolated strains were identified using biochemical methods. The Kirby-Bauer disk diffusion method, the combined disk method, and the approximate disk method were used to investigate the resistance of strains to the most commonly used antibiotics. Results: In total 123 strains of the Enterobacteriaceae family and 79 strains of the Enterococcus genus were isolated from all samples. The most common strains belonged to the genera Escherichia spp. (30,1 %), Kluyvera spp. (17,9 %), and Salmonella spp. (11,4 %), while among enterococci, the species E. faecalis and E. faecium were predominant. Isolated enterobacterial strains from both municipal wastewater treatment plants were most often resistant to azithromycin (81,1 %), ampicillin (77,9 %), and cefpodoxime (69,3 %), while 3,8 % of enterococcal strains were resistant to vancomycin. The multidrug resistance index exceeded 0,2 in 109 strains (88,6 %). The largest proportion (51,4 %) of resistant enterobacteria was found in samples from aeration tanks. Discussion and conclusion: Based on the obtained index of multiple resistance to antibiotics, we found that wastewater plants are a high-risk environment in which bacteria are exposed to pressures to develop resistance. The origin and composition of wastewater and wastewater treatment technologies are factors on which the spread of antimicrobial resistance among microorganisms in the natural environment and the impact on other living organisms, including humans, depend.

• Keywords: master's theses, sanitary engineering, antibiotics, bacteria, Enterobacteriaceae, Enterococcus, wastewater treatment plants, antibiotic resistance