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Prilagoditev listerij na benzalkonijev klorid
Podpac, Monika (Author), Jeršek, Barbka (Mentor) More about this mentor... This link opens in a new window

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Abstract
Namen našega dela je bil ugotoviti sposobnost prilagoditve izbranih sevov listerij na benzalkonijev klorid (BAC). Z metodo razredčevanja v mikrotitrski ploščici smo določili minimalno inhibitorno koncentracijo (MIKa) BAC. MIKa za posamezen sev smo preverili z rastno krivuljo in ugotovili, da imajo na rast vseh sevov inhibitorni učinek nižje koncentracije BAC, ki so variirale med 0,125-0,5x MIKa (MIKb). Prilagoditev sevov smo zato začeli z 0,25x MIKb BAC in jo glede na prilagoditev posameznega seva nadaljevali do 128x MIKb. Na BAC se je prilagodilo 40 % sevov bakterij vrste L. monocytogenes (od 4x do 8x MIKb) in 60 % sevov bakterij vrste L. innocua (8x MIKb). Nato smo določili stabilnost prilagoditve posameznega seva na BAC. Rezultati so pokazali, da je prišlo do razvoja proti BAC odpornega seva- L. monocytogenes ŽM 500, medtem ko je pri drugih prilagojenih sevih listerij minimalna inhibitorna koncentracija BAC ostala močno povišana glede na minimalno inhibitorno koncentracijo neprilagojenih sevov. V laboratorijskih razmerah smo pri 50 % testiranih sevov listerij dobili močno zmanjšano občutljivost na BAC, kar je zelo zaskrbljujoč rezultat, ki nakazuje smeri nadaljnjega raziskovanja, s katerim bi pridobili vpogled v mehanizme prilagoditve in razvoja odpornosti listerij. Hkrati pa prikazani rezultati kažejo na sicer sprejemljivo rutinsko uporabo metode razredčevanja v mikrotitrski ploščici, ki jo je za detajlne študije nujno kombinirati z drugimi metodami.

Language:Slovenian
Keywords:živilska mikrobiologija, Listeria monocytogenes, Listeria innocua, protimikrobne snovi, razkužila, kvartarne amonijeve spojine, benzalkonijev klorid, minimalna inhibitorna koncentracija, prilagoditev bakterij, razvoj odpornost
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:BF - Biotechnical Faculty
Year:2018
Publisher:[M. Podpac]
UDC:579.24+579.26:615.281.9:547.233.4
COBISS.SI-ID:4896376 Link is opened in a new window
Views:866
Downloads:1085
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Secondary language

Language:English
Title:Adaptation of Listeria spp. to benzalkonium chloride
Abstract:
The purpose of our work was to determine the ability of selected L. innocua and L. monocytogenes strains to adapt to benzalkonium chloride (BC). The minimum inhibitory concentration (MICa) of BC was determined with broth microdilution method, and with growth curve. From the latter we determined the lowest concentration of BC that had an inhibitory effect on growth of each listeria strain. This indicated sufficiently low concentrations at which the adaptation assay was started. We found that lower concentrations of BC, between 0.125x - 0.5x MICa, have an inhibitory effect on growth of selected strains of L. monocytogenes and L. innocua. Therefore, the adaptation assay started at 0.25x MICb BC, as determined by the growth curve, using 5 strains of L. innocua and 5 strains of L. monocytogenes. BC concentration was increased stepwise for all strains, up to a concentration of 16x MICb. 40 % of L. monocytogenes and 60 % of L. innocua strains were able to adapt to the higher BC concentrations than MICb. For those strains that were adapted to the higher BC concentrations, broth microdilution method was used to determine whether MICa of adapted strains remained raised. If MICa remained constant for seven days, we concluded that a BC resistant strain had developed. Among five adapted Listeria strains, MICa remained unchanged in one of L. monocytogenes strain which is a significant proportion for laboratory conditions. These results provide a great basis for further research, which might provide a more detailed insight into mechanisms responsible for adaptation and the development of BC resistance in Listeria.

Keywords:food microbiology, Listeria monocytogenes, Listeria innocua, antimicrobials, disinfectants, benzalkonium chloride, quarterium ammonium compounds, minimum inhibitory concentration, bacterial adaptation, resistance development

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