Development of a collagen dual-species biofilm model.The behaviour of P. aeruginosa and S. aureus during planktonic and biofilm mode of growth
Typ
Examensarbete för masterexamen
Program
Publicerad
2020
Författare
Temur, Özlem
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The prevalence of chronic wounds is increasing every year with aging population
and with chronic diseases such as diabetes and obesity. Chronic wounds do not only
affect many people worldwide but also brings major costs to the healthcare systems
globally. The wounds are colonised by both planktonic (free-living) bacteria and
bacteria in biofilms. Two species of bacteria, namely P. aeruginosa and S. aureus
are commonly found in chronic wounds and can result in severe infections together.
Although chronic wounds and wounds in general are polymicrobial, i.e. colonised
by several species, in vitro test methods are still single-species.
In this thesis work, there was an attempt to develop a dual-species collagen biofilm
model with P. aeruginosa and S. aureus. The goal was to develop a model in which
P. aeruginosa and S. aureus stayed at the same concentrations at 48 hours when
both species had reached the stationary phase. The growth behaviour of P. aeruginosa
and S. aureus in planktonic mono- and dual-species cultures with and without
agitation was determined and compared to the results acquired from mono- and
dual-species experiments in biofilms.
It was found that the concentration of S. aureus decreased in dual-species experiments
at 48 hours. The reduction in concentration could be linked to the presence
of virulence factors produced by P. aeruginosa. The start inoculum concentration
of P. aeruginosa was adjusted to lower values to investigate if S. aureus managed
to survive in environments with lower concentration of P. aeruginosa. However,
regardless of the start inoculum concentration of P. aeruginosa, a reduction of S.
aureus could be seen at 48 hours.
In conclusion, the development of the dual-species collagen model was not fulfilled
as S. aureus did not manage to survive at same concentrations at 48 hours as when
it reached the stationary phase. However, pre-established biofilms of S. aureus resulted
in the smallest reduction and could possibly be optimised further.
Beskrivning
Ämne/nyckelord
chronic wounds , biofilm , collagen , dual-species , bacteria , Pseudomonas aeruginosa , Staphylococcus aureus , in vitro model , planktonic , test method