Virulentni čimbenici bakterije Enterococcus faecium iz različitih izolacijskih izvora

master's thesis

• Title (english): Virulence factors of the bacteria enterococcus faecium from different isolation sources
• Author: Silvia Novak
• Mentor: Ivan Kosalec (mentor)
• Committee member: Ivan Kosalec (predsjednik povjerenstva)
• Committee member: Josipa Vlainić (član povjerenstva)
• Committee member: Petra Turčić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of microbiology); Zagreb
• Defense date and country: 2023-07-11, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Bakterija Enterococcus faecium je komenzalni organizmi u mikrobioti probavnog sustava čovjeka, ali ih
nalazimo i u okolišu, tlu, vodama, hrani, biljkama i životinjama. Ovi koki smatraju se i oportunističkim
patogenima jer mogu uzorkovati razne infekcije u čovjeka. Cilj ovog rada je ispitati osjetljivost prikupljenih
bakterijskih sojeva E. faecium na antimikrobni lijek vankomicin te ispitati slijedeće virulentne čimbenike;
stvaranje biofilma, β-hemolitičku aktivnost te hidrofobnost stanične površine. Prikupljeno je 90 sojeva
bakterije Enterococcus faecium iz tri različita izvora; klinički uzorci iz bolničke sredine, hrana te otpadne
vode. Iz svakog izvora uzeto je 30 sojeva. Ispitivanjem osjetljivosti sojeva na antibiotik vankomicin utvrđeno
je da je najveći broj rezistentnih sojeva prikupljeno iz bolničke sredine, a ispitivanjem sposobnosti stvaranja
biofilma pokazalo se da su sojevi izolirani iz bolnice i hrane značajno bolji produktori biofilma od sojeva
izoliranih iz otpadnih voda. Također, utvrđeno je da izolati iz hrane imaju najveću hidrofobnost stanične
površine, a ispitivanjem β-hemolitičke aktivnosti 90 sojeva utvrđeno je da su svega šest soja β-hemolitički
aktivna; tri izolata iz hrane, dva iz bolnice te jedan iz otpadnih voda. U ispitivanih sojeva rezistentnih na
vankomicin (VRE) nije uočena korelacija virulentnih čimbenika hidrofobnosti stanične površine i stvaranja
biofilma u uvjetima in vitro. Međutim, ispitivanje je provedeno na malom uzorku sojeva VRE te se ne može
izvući opći zaključak moguće korelacije. Iz dobivenih se podataka može zaključiti da postoji razlika u
virulentnim čimbenicima između izoliranih sojeva bakterije E. faecium, stoga se početna hipoteza pokazala
točnom.

Abstract (english)

The bacterium Enterococcus faecium is a commensal organism in the microbiota of the human digestive
system, but we also find it in the environment, soil, water, food, plants and animals. These cocci are also
considered opportunistic pathogens because they can sample various infections in humans. The aim of this
study is to test the sensitivity of the collected bacterial strains of E. faecium to the antimicrobial drug
vancomycin and to test the following virulence factors; biofilm formation, β-hemolytic activity and
hydrophobicity of the cell surface. 90 strains of Enterococcus faecium bacteria were collected from three
different sources; clinical samples from the hospital environment, food and waste water. 30 strains were taken
from each source. Testing the sensitivity of the strains to the antibiotic vancomycin showed that the largest
number of resistant strains were collected from the hospital environment and testing the ability to form
biofilms showed that strains isolated from hospitals and food are significantly better biofilm producers than
strains isolated from wastewater. Also, it was determined that isolates from food have the highest
hydrophobicity of the cell surface and testing the β-hemolytic activity of 90 strains revealed that only six
strains are β-hemolytically active; three isolates from food, two from the hospital and one from waste water.
From the examined vancomycin-resistant (VRE) strains, no correlation was observed between the virulence
factors of cell surface hydrophobicity and biofilm formation under in vitro conditions. However, the test was
conducted on a small sample of VRE strains and a general conclusion of a possible correlation cannot be
drawn. From the obtained data, it can be concluded that there is a difference in virulence factors between the
isolated strains of E. faecium bacteria, therefore the initial hypothesis proved to be correct.

• Keywords: Enterococcus faecium; virulencija; hemoliza; hidrofobnost stanične površine; biofilm
• Keywords (english): Enterococcus faecium; virulence; hemolysis; cell-surface hydrophobicity; biofilm.
• Language: croatian
• URN:NBN: urn:nbn:hr:163:511151
• Study programme: Title: Pharmacy; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra farmacije (magistar/magistra farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-12-01 11:33:01