Mehanizmi rezistencije na kolistin u Acinetobacter baumannii izoliranih iz otpadnih voda

undergraduate thesis

• Title (english): Mechanisms of colistin resistance in Acinetobacter baumannii isolated from wastewater
• Author: Andrea Kosier
• Mentor: Jasna Hrenović (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2022-05-13, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Prema Svjetskoj zdravstvenoj organizaciji višestruko rezistentni izolati bakterije Acinetobacter baumannii
najveća su prijetnja ljudskom zdravlju. Gubitak dostupnih antibiotika za liječenje infekcija uzrokovanih
višestruko rezistentnim A. baumannii oživio je klinički interes za kolistin kao antibiotik posljednje linije
obrane. Međutim, slučajevi kolistin-rezistentnih bakterija u bolnicama i otpadnim vodama već su
zabilježeni. Otpadne vode pružaju bakterijama dobre uvjete za horizontalni prijenos gena te predstavljaju
potencijalan put širenja gena rezistencije i rezistentnih izolata po cijelom ekosustavu. U ovome su radu
prikupljeni podaci o mehanizmima rezistencije na kolistin u A. baumannii izoliranih iz otpadnih voda. U
izolatima iz otpadnih voda pronađene su mutacije koje su karakteristične za kliničke izolate rezistentne
na kolistin, a to su mutacije u pmrCAB operonu i u genima lpxA, lpxC i lpxD koje redom uzrokuju
modifikaciju lipopolisaharida, odnosno potpuni gubitak lipopolisaharida vanjske membrane. Nadalje, u
vodenom okolišu, premda ne u izolatima A. baumannii iz otpadnih voda, uočena je sveprisutnost
plazmidnih mcr gena odgovornih za kolistinsku rezistenciju. Pretpostavlja se da rezistencija na kolistin
nije glavna uloga tih gena, već oni služe za obranu bakterija od bakteriofaga i kationskih antimikrobnih
peptida kralježnjaka i beskralježnjaka. Također, pronađeni su sojevi koji su vjerojatno postali kolistinrezistentni zbog razvoja unakrsne rezistencije pod utjecajem drugih pozitivno nabijenih onečišćivača iz
okoliša.

Abstract (english)

World Health Organization declared multidrug-resistant Acinetobacter baumannii as one of the greatest
threats to human health. Continuous loss of effective antibiotics for therapies of multidrug-resistant A.
baumannii has revived clinical interest in colistin as a last-line antibiotic. However, cases of colistinresistant bacteria have already been reported in hospitals and wastewaters. Wastewaters represent
hotspots for horizontal gene transfer and a potential pathway for spreading resistant genes and isolates
throughout the ecosystem. This thesis collected data on the mechanisms of A. baumannii colistin
resistance isolated from wastewaters. Characteristic mutations found in colistin-resistant clinical isolates,
include either modification or complete loss of lipopolysaccharides due to mutations in the pmrCAB
operon and lpxA, lpxC and lpxD, respectively, were found in isolates from wastewaters. Furthermore,
owning to a large presence of plasmid mcr genes observed in the aquatic environment, although not in
A. baumannii isolates from wastewater, it’s believed that the main role of these genes isn’t resistance to
colistin as it was previously assumed, hence they play a role in the bacterial defense system against
bacteriophages and cationic antimicrobial peptides of vertebrates and invertebrates. Also, the
development of cross-resistance to colistin, probably under the influence of other positively charged
pollutants, was observed.

• Keywords: Acinetobacter baumannii; kolistin; antibiotska rezistencija; otpadne vode
• Keywords (english): Acinetobacter baumannii; colistin; antibiotic resistance; wastewater
• Language: croatian
• URN:NBN: urn:nbn:hr:217:130241
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-05-25 07:34:06