138 research outputs found
Colistin resistance in acinetobacter baumannii: Molecular mechanisms and epidemiology
: Acinetobacter baumannii is recognized as a clinically significant pathogen causing a wide
spectrum of nosocomial infections. Colistin was considered a last-resort antibiotic for the treatment of
infections caused by multidrug-resistant A. baumannii. Since the reintroduction of colistin, a number
of mechanisms of colistin resistance in A. baumannii have been reported, including complete loss of
LPS by inactivation of the biosynthetic pathway, modifications of target LPS driven by the addition
of phosphoethanolamine (PEtN) moieties to lipid A mediated by the chromosomal pmrCAB operon
and eptA gene-encoded enzymes or plasmid-encoded mcr genes and efflux of colistin from the cell.
In addition to resistance to colistin, widespread heteroresistance is another feature of A. baumannii
that leads to colistin treatment failure. This review aims to present a critical assessment of relevant
published (>50 experimental papers) up-to-date knowledge on the molecular mechanisms of colistin
resistance in A. baumannii with a detailed review of implicated mutations and the global distribution
of colistin-resistant strains
Biogenic silencers of Pseudomonas aeruginosa virulence
Pseudomonas aeruginosa jedan je od najznaÄajnijih uzroÄnika unutarbolniÄkih infekcija Äiji je terapijski tretman
konvencionalnim antibioticima sve ÄeÅ”Äe neefikasan usled rezistencije na antibiotike. Inovativni vidovi
kontrole infekcija, poput utiÅ”avanja meÄuÄelijske komunikacije bakterija, a time i onemoguÄavanja virulencije
i inhibicije patogenog fenotipa su stoga od izuzetnog znaÄaja. U ovom radu biÄe predstavljena istraživanja
koja su bazirana na prirodnom svojstvu bakterija koje dele ekoloÅ”ke niÅ”e da saraÄuju, ali i kompetiraju,
na osnovu Äega su analizirane Delftia tsuruhatensis i Burkholderia cepacia koje tokom infekcija kolokalizuju
sa P. aeruginosa. Pokazano je da D. tsuruhatensis 11304 produkuje C18-HSL koji inhibira virulenciju P. aeruginosa
i rekonstituiÅ”e osetljivost na antibiotike, a takoÄe je po prvi put u literaturi opisano prisustvo dihidroksi-
C18-HSL u bioloŔkim uzorcima. Opisane su i laktonaze vrste B. cepacia BCC4135 koje degraduju
autoinducere komunikacije P. aeruginosa i inhibiraju ekspresiju faktora virulencije. UtvrÄena je njihova supstratna
specifiÄnost i ukazano na razliÄitu bioloÅ”ku funkciju u zavisnosti od lokalizacije.Pseudomonas aeruginosa is a leading cause of nosocomial infections, whose therapeutic treatment with
conventional antibiotics is increasingly ineffective due to antibiotic resistance. Inovative approaches of infection
control, such as silencing the bacterial quorum sensing system and thus virulence and pathogenic
phenotype inhibition are of great importance. In this study, there will be presented research based on natural
feature of bacteria that share the same ecological niche to coordinate, but also to compete, based on
which Delftia tsuruhatensis and Burkholderia cepacia that colocalize with P. aeruginosa during infections were
analysed. D. tsuruhatensis 11304 has been shown to produce C18-HSL which inhibits P. aeruginosa virulence
and reconstitutes antibiotic susceptibility, and the presence of dihydroxy-C18-HSL in biological samples has
also been described for the first time in the literature. B. cepacia BCC4135 lactonases that degrade autoinducers
of P. aeruginosa quorum sensing system and inhibit virulence factor expression have also been reported.
Their substrate specificity was determined and different biological function depending on their
localization was indicated.Jedan deo ovog rada realizovan je na Dipartimento di Scienze Chimiche, UniversitĆ di Napoli Federico
II, Napulj, Italija pod rukovodstvom prof dr Antonio Molinaro i dr Flaviana Di Lorenzo, kojima se ovom prilikom
zahvaljujem. Hvala dr sci med Zorici VasiljeviÄ sa Instituta za zdravstvenu zaÅ”titu majke i deteta Srbije āāDr Vukan ÄupiÄāā
koja je obezbedila kliniÄke izolate koriÅ”Äene u ovom radu, kao i dr Milanu KojiÄu i drugim saradnicima Laboratorije za
molekularnu mikrobiologiju Instituta za molekularnu genetiku i genetiÄko inženjerstvo za izuzetnu pomoÄ tokom
izrade eksperimenata
Molecular characterization of semi-hard homemade cheese microflora
U poslednjoj deceniji zabeležen je nagli razvoj molekularnih tehnika baziranih na 16S i 23S rRNK, koje se koriste u izuÄavanju biodiverziteta mikroorganizama. U ovom radu ispitivana je mikroflora polutvrdog sira pripremljenog u domaÄinstvu. Zbog visokog sadržaja masti u ovom siru razvili smo novu tehniku za izolaciju totalne DNK iz sira (metod je baziran na bead beating-u). Brza izolacija DNK iz mikroflore sira omoguÄila nam je molekularnu identifikaciju BMK (BAKTERIJE MLEÄNE KISELINE) na osnovu umnožavanja gena za 16S rRNK PCR metodom. Za umnožavanje su koriÅ”Äeni prajmeri specifiÄni za gene 16S rRNK lakto-bacila, ali su uslovi PCR reakcije bili takvi da su omoguÄavali i umnožavanje gena 16S rRNK laktokoka. Rezultati RFLP analize pokazali su da mikrofloru sira pripremljenog u domaÄinstvu Äine predominantno laktokoke.This decade has shown an impressive development in the application of molecular techniques based on 16S and 23S rRNA genes to study the microbial diversity in various ecosystems. Microflora of semi-hard homemade cheese was examined in this work. We developed a novel technique for DNA extraction (a bead beating based method) due to high fat content of this cheese. Rapid extraction of DNA from cheese microflora enabled a molecular identification of the LAB (Lactic Acid Bacteria) strains based on PCR amplification of 16S RNA coding sequences. The specific primers for 76S RNA gene of lactobacilli were used for amplification. The PCR reaction was performed at lower temperature, where the specificity of the annealing reaction was reduced and lactococcal sequences of 16S RNA genes were also amplified. The results of RFLP analysis revealed that the microflora of Doboj homemade cheese encompases mostly lactococci
Supplementary data for the article: VatiÄ, S.; MirkoviÄ, N.; MiloÅ”eviÄ, J. R.; JovÄiÄ, B.; PoloviÄ, N. Ä. Broad Range of Substrate Specificities in Papain and Fig Latex Enzymes Preparations Improve Enumeration of Listeria Monocytogenes. International Journal of Food Microbiology 2020, 334, 108851. https://doi.org/10.1016/j.ijfoodmicro.2020.108851
Supplementary material for: [https://doi.org/10.1016/j.ijfoodmicro.2020.108851]Related to published version: [https://cherry.chem.bg.ac.rs/handle/123456789/4090
Supplementary data for the article: MiloÅ”eviÄ, J.; PetriÄ, J.; JovÄiÄ, B.; JankoviÄ, B.; PoloviÄ, N. Exploring the Potential of Infrared Spectroscopy in Qualitative and Quantitative Monitoring of Ovalbumin Amyloid Fibrillation. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy 2020, 229. https://doi.org/10.1016/j.saa.2019.117882
Supplementary material for: [https://doi.org/10.1016/j.saa.2019.117882]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3884]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3895
Post-translational regulation of the RpoS and PsrA genes in pseudomonas putida WCS358: The role of ClpXP protease
RpoS i PsrA proteini su kljuÄni transkripcioni regulatori koji se kod pseudomonada aktiviraju u odgovoru na stacionarnu fazu rasta. Cilj ove studije bio je utvrÄivanje uloge ClpXP (ATP zavisna serin proteaza) u stabilnosti RpoS i PsrA proteina tokom razliÄitih faza rasta u Pseudomonas putida WCS358. "Western blot" analiza proteinskih ekstrakata P. putida WCS358 i P. putida WCS358 clpX::Km iz rane eksponencijalne, Kasne eksponencijalne i stacionarne faze rasta, sa antitelima na RpoS i PsrA, pokazala je da ClpXP degraduje RpoS i PsrA u ranoj eksponencijalnoj fazi rasta.The RpoS and PsrA proteins are key transcriptional regulators that are activated in response to the stationary phase of growth in pseudomonads. This study was designed to establish whether ClpXP (ATP-dependent serine protease) regulates levels of RpoS and PsrA in Pseudomonas putida WCS358. Western blot analysis of P. putida WCS358 protein extracts from the early exponentianl, late exponential, and stationary phases of growth with antibodies against RpoS and PsrA revealed that these proteins are degraded by ClpXP in the early exponential phase of growth. The obtained results demonstrate a role for ClpXP protease in post-translational regulation of proteins encoded by the rpoS and psrA genes in Pseudomonas spp
Effect of methionine and cysteine deprivation on growth of different natural isolates of Lactobacillus spp. in chemically defined media
Cilj ovog rada je bio da se utvrdi sposobnost prirodnih izolata laktobacila,izolovanih iz razliÄitih ekoloÅ”kih niÅ”a da rastu u hemijski definisanom medijumu sa ili bez prisustva aminokiselina koje sadrže sumpor, metionin i/ili cistein. Dobijeni rezultati su pokazali da je esencijalna aminokiselina za rast izolata L. paracasei subsp. paracasei BGHN14 i BGSJ2-8 cistein, dok je za izolate BGHN40, BGCG31, BGHV54T, koji pripadaju vrsti L. plantarum-metionin. Metionin je esencijalna aminokiselina za rast soja L. rhamnosus BGHV58T. Ostali analizirani sojevi,kao Å”to su L. plantarum BGSJ3-18,BGZB19,BGHV52Ta i BGHV43T za svoj rast zahtevaju prisustvo obe aminokiseline u medijumu.The purpose of this study was to determine the ability of natural isolates of lactobacilli from different ecological niches to grow in a chemically defined medium in the presence or absence of sulphur-containing amino acids, methionine and/or cysteine. The obtained results indicate that cysteine is essential for growth of L. paracasei subsp. paracasei BGHN14 and BGSJ2-8, while methionine is essential for isolates BGHN40, BGCG31, and BGHV54T of the species L. plantarum. Methionine is also essential for growth of L. rhamnosus BGHV58T. Other analyzed strains, such as L. plantarum BGSJ3-18, BGZB19, BGHV52Ta, and BGHV43T, require the presence of both amino acids for their growth
Emergence of VIM-2 metallo-beta-lactamase-producing Pseudomonas aeruginosa isolates in a paediatric hospital in Serbia
Molecular detection and surveillance of the
resistance genes harboured by
Pseudomonas aeruginosa are becoming
increasingly important in assessing and
controlling spread and colonization in
hospitals, and in guiding the antibiotic
treatment of infections. Metallo-blactamase (MBL)-producing P. aeruginosa
strains are slowly but steadily increasing
within hospitals, causing outbreaks and/or
hyperendemic situations in some centres,
mostly in the Far East and the south of
Europe (Queenan & Bush, 2007). The
global dissemination of MBL-producing
P. aeruginosa strains has also reached the
Balkan region (Lepsanovic et al., 2008;
Sardelic et al., 2003). The objective of our
study was to detect and characterize P.
aeruginosa isolates producing MBLs from
the 400-bed paediatric tertiary care
hospital Mother and Child Health Institute
of Serbia āDr Vukan Cupic
Characterization of lactococci isolated from homemade kefir
Pet izolata laktokoka proizvoÄaÄa bakteriocina izolovanih iz kefira pripremljenog na tradicionalan naÄin determinisano je kao Lactococcus lactis subsp. lactis. Analizirani izolati poseduju razliÄite plazmidne profile i meÄu njima nije detektovana uzajamna antimikrobna aktivnost. TakoÄe prirodni izolat BGKF26 je rezistentan na aktivnost soja NP45, proizvoÄaÄa nizina. Eksperimenti ÄiÅ”Äenja plazmida pokazali su da se geni _a sintezu bakteriocina i proteinaza nalaze na razliÄitim genetiÄkim elementima, osim kod izolata BGKF26. Sinteza analiziranih bakteriocina zavisi od koncentracije kazitona ili triptona u medijumu. ViÅ”e koncentracije kazitona ili triptona indukuju bakteriocinsku aktivnost. Hibridizacioni eksperimenti su pokazali da su analizirani bakteriocini najverovatnije sliÄni laktokokcinima.Five bacteriocin-producing lactococci isolates from traditionally prepared kefir were determined as Lactococcus lactis subsp. lactis. The analyzed isolates showed different plasmid profiles and no cross inhibition between them was detected. Moreover, natural isolate BGKF26 was resistant to the antimicrobial activity of nisin producing strain NP45. Plasmid curing experiments revealed that the genes encoding bacteriocin and proteinase production are located on separate genetic elements, except in BGKF26. Production of the tested bacteriocins depends on the concentration of casitone or triptone in the medium. Higher concentrations of casitone or triptone induce bacteriocin activity. Our DNA-DNA hybridization analyses suggest that the analyzed antimicrobial compounds probably are lactococcin-like bacteriocins
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