Klebsiella pneumoniae is a Gram-negative bacterium commonly giving rise to nosocomial infections especially in immunocompromised individuals. The high occurrence of antibiotic resistant K. pneumoniae strains in combination with the bacterium’s ability to form biofilms that are naturally more tolerant to antibiotic treatment represents a burden for the healthcare system due to potential therapeutic failure. In this study, we were investigating the effect of gentamicin, cefotaxime and ciprofloxacin on biofilm formation and eradication of a multi-resistant ESBL-producing K. pneumoniae strain associated with an outbreak at the Uppsala University Hospital in Uppsala, Sweden, from 2005 to 2007. Multidrug resistance was encoded on the pUUH239.2 plasmid. We also studied how resistant bacteria are selected for in mixed biofilm populations consisting of both resistant and susceptible bacteria under antibiotic treatment. Biofilms were grown in vitro by using an in-the-lab developed peg model. Biofilms were either allowed to form in the presence of the antibiotics or pre- formed and then exposed to antibiotic treatment at different time points. Our results suggest that gentamicin, cefotaxime and ciprofloxacin inhibit biofilm formation at concentrations below the minimum inhibitory concentration (MIC) and that biofilms become more tolerant to antibiotic treatment with increasing maturation. We further observed that increasing antibiotic concentrations select for the presence of the plasmid in less mature biofilms. Overall, these findings highlight the need of early antibiotic treatment during infection and give insight into the dynamics of resistant and susceptible bacteria in mixed biofilm populations in the presence of antibiotics.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-384455 |
| Date | January 2019 |
| Creators | Tomaschek, Valentina Vynona |
| Publisher | Uppsala universitet, Institutionen för biologisk grundutbildning |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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