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Population structure and biofilm formation of Pseudomonas aeruginosa isolated from patients with severe burn wounds at Tygerberg Hospital.

dc.contributor.advisorMae, Newton-Footen_ZA
dc.contributor.advisorAndrew, Whitelawen_ZA
dc.contributor.authorBernardus Daniël, Van Biljonen_ZA
dc.contributor.otherFaculty of Medicine and Health Sciences. Dept. of Pathology. Division Medical Microbiology.en_ZA
dc.date.accessioned2017-10-18T07:00:14Z
dc.date.accessioned2017-12-11T10:43:29Z
dc.date.available2017-10-18T07:00:14Z
dc.date.available2017-12-11T10:43:29Z
dc.date.issued2017-12
dc.identifier.urihttp://hdl.handle.net/10019.1/102702
dc.descriptionThesis (MSc)--Stellenbosch University, 2017en_ZA
dc.description.abstractENGLISH ABSTRACT : Pseudomonas aeruginosa is a common opportunistic pathogen which is responsible for more than 11% of nosocomial infections including urinary tract infections (UTI’s), bacteraemia, pneumonia and soft tissue infections. Little is known about P. aeruginosa associated infections in burn wound patients in South Africa, and in particular at Tygerberg hospital. Burn wound patients are highly vulnerable to infections due to natural defence destruction. P. aeruginosa has the ability to form a biofilm and cause persistent biofilm associated infections. The biofilm acts as a protective layer defending organisms against the environment, host immune system and antibiotic treatment. P. aeruginosa infections have a mortality rate of 40-50% in burn wound patients. This study aimed to determine the population structure of P. aeruginosa isolated from the burns unit and burns ICU in comparison to isolates from other wards at Tygerberg hospital, to investigate their ability to form biofilms and to determine the impact of various antibiotics on biofilm formation. P. aeruginosa isolates from blood cultures, swabs and tissue specimens from adult and paediatric patients at Tygerberg hospital were collected from February 2015 to March 2016. Forty isolates from the burns unit and 40 isolates from outside the burns unit were used for the study. Multiple locus variable number tandem repeat analysis (MLVA) was used for strain typing. Biofilm formation was assessed by crystal violet staining. The strength of biofilm formation of the isolates was determined after a 12h incubation period and the effects of varying concentrations of four different classes of antibiotic on biofilm formation was determined over a 24 hour period. Forty two different MLVA types were described, of which ten were assigned to two or more isolates. Thirty two MLVA patterns were unique to a single isolate. MLVA type 1 was the most abundant MLVA type; 60% of the isolates from the burns unit and burns ICU were type 1. The predominance of a single MLVA type within the burns unit implies nosocomial transmission within the burns unit. Greater diversity was observed outside the burns unit. P. aeruginosa appeared to form multiple biofilm formation patterns. Three distinct patterns of biofilm formation could be described after 10 hours incubation. These patterns did not correlate with MLVA type. The effect of exposure to four antibiotics (cefepime, ciprofloxacin, imipenem, and gentamicin) on biofilm formation over time was shown to differ between organisms with early and late onset biofilm formation patterns, but is not predicted by MLVA type. The mechanisms of action of the antibiotics also did not seem to predict the response since two antibiotics with the same mechanism of action (cefepime and imipenem) had different biofilm formation patterns. Increased knowledge of the P. aeruginosa population structure and biofilm forming ability in this patient group, and enhanced understanding of the effect of antibiotic treatment on biofilm formation may enable improvements in transmission prevention, the selection and use of antibiotics for treatment and, ultimately, improve patient outcome.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING : Pseudomonas aeruginosa is ‘n algemene opportunistiese patogeen wat verantwoordelik is vir meer as 11% van hospitaalinfeksies wat urienweginfeksies, bakteremie, longontsteking en sagteweefsel infeksies insluit. Daar is min inligting beskikbaar rondom P. aeruginosa infeksies in brandwondpatiënte in Suid Afrika, spesifiek in Tygerberg hospital. Brandwondpatiënte is hoogs vatbaar vir infeksies as gevolg van die vernietiging van hul natuurlike verdedigingstelsel. P. aeruginosa het die vermoë om ‘n biofilm te vorm en ‘n voortdurende biofilmgeassosieerde infeksie te veroorsaak. Die biofilm tree op as ‘n beskermingslaag wat die organismes beskerm teen die omgewing, die gasheer se immuunstelsel en antibiotiese behandeling. P. aeruginosa is verantwoordelik vir ‘n 40-50% sterftesyfer in patiënte met brandwonde. Hierdie studie is daarop gemik om die bevolkingstruktuur van P. aeruginosa, geisoleer uit die brandwondeenheid en brandwond intensiewesorgeenheid te vergelyk met isolate van ander eenhede in Tygerberg Hospitaal ten opsigte van hul vermoë om biofilms te vorm en die effek van antibiotika op biofilmvorming. P. aeruginosa isolate was ingesamel van bloedkulture, deppers en weefsel monsters van volwasse en pediatriese patiënte in Tygerberg hospital oor die tydperk van Februarie 2015 tot Maart 2016. Veertig isolate vanuit die brandwondeenheid en buite die brandwondeenheid onderskeidelik was gebruik in die studie. Multi lokus veranderlike aantal tandem herhaling ontleding (MLVA) was uitgevoer om stamtipering te doen. Die vorming van die biofilms was bepaal met kristalvioletkleuring na ‘n 12-uur inkuberingsperiode, terwyl die effek wat vier antibiotika met verskillende konsentrasies en meganismes van werking oor ‘n 24-uur inkubasieperiode bepaal was. Twee-en-veertig verskillende MLVA tipes was geidentifiseer waarvan tien van die tipes twee of meer organisme besit. Twee-en-dertig MLVA patrone was uniek en het slegs een organisme besit. MLVA tipe 1 was die volopste; sowat 60% van brandwondeenheid en brandwond intensiewesorgeenheid isolate het aan MLVA tipe 1 behoort. Die oorheersing van hierdie MLVA tipe binne die brandwondeenheid/intensiewesorgeenheid impliseer dat daar wel oordrag binne-in die eenheid plaasvind. Daar was meer stamdiversiteit buite die brandwond eenheid. P. aeruginosa het drie verskillende biofilm patrone gevorm na 10 ure van inkubering waarvan daar geen ooreenstemming was tussen verskillende MLVA tipes nie. Die invloed van vier verskillende antibiotikas (cefepime, ciprofloxacin, imipenem en gentamicin) op die vorming van ‘n biofilm het getoon dat die aanvanklike hoeveelheid biofilm wat ‘n organisme vorm ‘n groot invloed op die werking van antibiotika het en dat daar ook geen ooreenkoms is tussen die biofilmvorming van organismes van dieselfde MLVA tipe. Die meganismse van aksie het ook geen merkwaardige impak getoon nie aangesien twee antibiotikas wat dieselfde aksie toon (cefepime and imipenem), biofilmvorming verskillend geaffekteer het. Verhoogde kennis van die P. aeruginosa bevolkingstruktuur en biofilmvormingsvermoë in hierdie groep pasiënte en ‘n verbeterde begrip van wat die effek van antibiotikabehandeling op biofilms is mag help om die uitkomste van gereelde oordrag en kliniese behandeling te verbeter.af_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectBiofilm formationen_ZA
dc.subjectUCTDen_ZA
dc.subjectBurns and scalds -- Treatment -- South Africaen_ZA
dc.subjectPseudomonas aeruginosa infectionsen_ZA
dc.subjectBurns and scalds -- Research -- South Africaen_ZA
dc.titlePopulation structure and biofilm formation of Pseudomonas aeruginosa isolated from patients with severe burn wounds at Tygerberg Hospital.en_ZA
dc.typeThesisen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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