Mehanizmi rezistencija na antibiotike u enetrobakterija otpornih na karbapeneme

doctoral thesis

• Title (english): Mechanisms of antimicrobial resistance in carbapenem-resistant enterobacteriaceae
• Author: Marko Jelić
• Mentor: Arjana Tambić Andrašević (mentor)
• Committee member: Gordana Maravić Vlahoviček (predsjednik povjerenstva)
• Committee member: Maja Šegvić Klarić (član povjerenstva)
• Committee member: Ana Budimir (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; Zagreb
• Defense date and country: 2018-06-19, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy
• Universal decimal classification (UDC): 615 - Pharmacology. Therapeutics. Toxicology

Abstract

Ovo istraživanje provedeno je s ciljem da se utvrde mehanizmi rezistencije na karbapeneme, njihova prevalencija, pozadina višestruke rezistencije i epidemiološke poveznice među izolatima enterobakterija koji su pokazivali smanjenu osjetljivost na karbapeneme na području Republike Hrvatske tijekom 2011. i 2012. godine. Od 250 prikupljenih izolata, iz 22 mikrobiološka laboratorija, većina je pripadala vrstama K. pneumoniae (60,4 %) i E. cloacae (33,2 %). Analizirani izolati bili su višestruko rezistentni s varijabilnom stopom rezistencije na karbapeneme. 65,6 % izolata nije proizvodilo karbapenemaze iako je u analiziranoj zbirci detektirana proizvodnja karbapenemaza KPC-2, VIM-1, NDM-1 i OXA-48. Smanjena osjetljivost na ertapenem temeljena na smanjenoj propusnosti bakterijske stanice u izolata K. pneumoniae bila je povezana sa sniženom ekspresijom gena ompK35 i proizvodnjom beta-laktamaze CTX-M-15, dok je u izolata E. cloacae uočena snižena ekspresija gena ompC. Utvrđeno je poliklonsko širenje karbapenemaza, uz iznimku karbapenemaze KPC-2 čije je širenje povezano s klonom ST258 K. pneumoniae. Širenje karbapenemaze VIM-1 meĊu E. cloacae povezano je s klonskim tipovima ST92, ST200 i ST105. Klonski tipovi ST15 i ST16 K. pneumoniae glavni su pokretač širenja karbapenemaza VIM-1, NDM-1 i OXA-48. Širenje enterobakterija koje ne proizvode karbapenemaze bilo je polklonsko, no genetička varijabilnost je ovisila o promatranoj bakterijskoj vrsti. Izolati E. cloacae koji ne proizvode karbapenemaze pokazivali su povećanu genetičku raznolikost, dok je smanjena raznolikost izolata K. pneumoniae bila posljedica širenja klonskog tipa ST437. Geni koji kodiraju karbapenemaze smješteni su na plazmidima pri čemu je gen blaKPC-2 identificiran na plazmidima FIIs, blaNDM-1 na IncA/C, IncL/M i IncR, blaVIM-1 na IncN i IncL/M i blaOXA-48 na epidemijskom IncL/M plazmidu veličine ~60 kb. Pojava i širenje enterobakterija otpornih na karbapeneme je problem globalnih razmjera koji nije zaobišao niti Republiku Hrvatsku. Mehanizmi rezistencije na antibiotike enterobakterija otpornih na karbapeneme analiziranih u ovom radu i njihov epidemiološki kontekst u skladu su s općom slikom rezistencije enterobakterija na karbapeneme koja se opisuje u znanstvenoj literaturi.

Abstract (english)

The aim of this study was to identify and assess the prevalence of resistance mechanisms underlying carbapenem resistance, to investigate multidrug resistance and to elucidate genetic relatedness among carbapenem non-susceptible enterobacterial isolates collected during 2011 and 2012 in Croatia. Out of 250 isolates collected form 22 clinical microbiology laboratories, most were K. pneumoniae (60.4 %) and E. cloacae (33,2 %). All isolates were multiple drug resistant and showed varying levels of resistance to carbapenems. In 65.6 % of isolates carbapenem non-susceptibility was not exhibited via carbapenemase production even though KPC-2, VIM-1, NDM-1 and OXA-48 production was observed. Ertapenem non-susceptibility due to reduced permeability in K. pneumoniae isolates was associated with ompK35 gene repression and CTX-M-15 production, while in E. cloacae isolates ompC gene repression was observed. Carbapenemase dissemination was polyclonal with exception of KPC-2 which was propagated exclusively by the spread of ST258 K. pneumoniae clone. Spread of VIM-1-producing E. cloacae was mainly associated with ST92, ST200 and ST105 clones. ST15 and ST16 K. pneumoniae clones were recognized as a main reservoir of blaVIM-1, blaNDM-1 and blaOXA-48 genes. Spread of carbapenemase non-producing Enterobacteriaceae was polyclonal but genetic diversity of isolates was species specific. Carbapenemase non-producing E. cloacae exhibited greater genetic variability, but in K. pneumoniae homogenous genetic background was associated with successful clonal spread of ST437. Plasmid localization of all carbapenemase encoding genes was observed. blaKPC-2 gene was detected on FIIs plasmids, blaNDM-1 on IncA/C, IncL/M and IncR, blaVIM-1 on IncN and IncL/M and blaOXA-48 on an IncL/M ~60 kb epidemic plasmid. Emergence and spread of carbapenem non-susceptible Enterobacteriaceae is a global healthcare problem which is also recognized in Croatia. Mechanisms of carbapenem resistance and epidemiological background of isolates observed in this study is consistent with reports describing carbapenem non-susceptible Enterobacteriaceae on a global level.

• Keywords: Enterobacteriaceae; otpornost na karbapeneme; karbapenemaze; molekularna epidemiologija; plazmidi; KPC-2; VIM-1; NDM-1; OXA-48
• Keywords (english): Enterobacteriaceae; carbapenem non-susceptible; carbapenemases; molecular epidemiology; plasmids; KPC-2; VIM-1; NDM-1; OXA-48
• Language: croatian
• URN:NBN: urn:nbn:hr:163:737644
• Study programme: Title: Pharmacy and biochemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti (doktor znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-04-04 15:47:35