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Experimental evolution in biofilm models of Pseudomonas aeruginosa using mutagenesis screening reporters

Zaborskytė, Greta (2016) MOBT01 20152
Degree Projects in Molecular Biology
Popular Abstract
What does not kill bacteria, makes them stronger

Bacteria most often gather together to form communities called biofilms, which represent the underlying cause of 60% of all infections. Bacteria hidden in the biofilms cannot be eliminated by the human immune system and by antibiotics, therefore, they cause persistent infections which require long-term antibiotic therapy. One of the unwanted effects of the antibiotic treatment, especially in biofilms, is the emergence of antibiotic-resistant bacteria, which are considered a global threat. It is assumed that the continuous rise of antibiotic resistance will lead to more people dying of infections in year 2050 than currently of cancer. Our study shows the fast development of antibiotic... (More)
What does not kill bacteria, makes them stronger

Bacteria most often gather together to form communities called biofilms, which represent the underlying cause of 60% of all infections. Bacteria hidden in the biofilms cannot be eliminated by the human immune system and by antibiotics, therefore, they cause persistent infections which require long-term antibiotic therapy. One of the unwanted effects of the antibiotic treatment, especially in biofilms, is the emergence of antibiotic-resistant bacteria, which are considered a global threat. It is assumed that the continuous rise of antibiotic resistance will lead to more people dying of infections in year 2050 than currently of cancer. Our study shows the fast development of antibiotic resistance in biofilms of human pathogen Pseudomonas aeruginosa treated with low doses of antibiotic called ciprofloxacin. These findings show biofilms as a source of antibiotic resistance that might spread from patient to patient.

We wanted to find out when and where ciprofloxacin-resistant bacteria occur in biofilms. We looked for resistant bacteria which pump out (throw away) the antibiotic. However, one cannot differentiate between resistant and sensitive bacteria just by looking at them. Therefore, we created a tool, based on the production of green fluorescent protein, which allowed us to follow the development of resistant bacteria (green) among the sensitive ones (red).

We found that treatment with low doses of ciprofloxacin (not killing) led to a rapid increase in the number of resistant bacteria in two different types of biofilm models. Using advanced microscopy techniques, we could observe that, firstly, under ciprofloxacin treatment, the sensitive, red bacteria showed signs of stress (became long) and later, green resistant bacteria developed from the red stressed cells. After having started to produce more pumps throwing antibiotic out of the cells (the green ones), they could happily thrive by clumping together (see Fig. 1).

Our findings illustrate how important it is to use as high antibiotic doses as possible or use combination of more than one antibiotic in order to avoid the appearance of the resistant bacteria equipped with powerful protective weapons.


Supervisors Oana Ciofu and Jens Bo Andersen, Costerton Biofilm Center (University of Copenhagen)
Master’s Degree Project 60 credits in Molecular Biology (Microbiology) 2016
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Zaborskytė, Greta
supervisor
organization
course
MOBT01 20152
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8891814
date added to LUP
2016-09-15 11:59:22
date last changed
2016-09-15 11:59:22
@misc{8891814,
  author       = {Zaborskytė, Greta},
  language     = {eng},
  note         = {Student Paper},
  title        = {Experimental evolution in biofilm models of Pseudomonas aeruginosa using mutagenesis screening reporters},
  year         = {2016},
}