Serum inhibits P. aeruginosa biofilm formation on plastic surfaces and intravenous catheters.
BACKGROUND
Biofilm formation on medical devices such as intravenous catheters is a serious manifestation of Pseudomonas aeruginosa infections. Serum has bactericidal activity, a function of multiple serum components. In this study, we determined the effect of serum and serum components on the formation of P. aeruginosa biofilm.


METHODS
We examined the effect of adult bovine serum (ABS) or bovine serum albumin (BSA) on biofilm development on plastic coverslips. This was done using both static and continuous flow-through culture systems and P. aeruginosa strain PAO1. Biofilms were quantified using crystal violet assays and visualized using confocal scanning laser microscopy and scanning electron microscopy. We examined the effect of ABS on PAO1 swimming and twitching motilities (both contribute to P. aeruginosa biofilm development). We also analyzed the inhibitory effect of adult human serum (AHS) and plasma (AHP) on PAO1 biofilm development on plastic coverslips and intravenous catheters.


RESULTS
Compared with M9 minimal medium (M9), 10% ABS-supplemented medium (M9/ABS-10) caused a significant decrease in biofilm development. Coverslips precoated with M9/ABS-10 failed to develop biofilm when placed in M9. In addition to reduced biofilm formation, adding ABS to M9 reduced an already-developed PAO1 biofilm. Compared with M9, M9/ABS-10 enhanced PAO1 twitching motility considerably, but did not affect swimming motility. Similar to ABS, BSA blocked biofilm formation but did not affect PAO1 twitching motility. Both AHS and AHP blocked PAO1 biofilm formation on plastic coverslips and intravenous catheters.


CONCLUSIONS
These results suggest that as part of the host innate resistance, serum inhibits P. aeruginosa biofilm formation on plastic surfaces, including intravenous catheters. Two possible scenarios for this inhibition include blocking the direct interaction between P. aeruginosa and the substrates, and the enhancing P. aeruginosa twitching motility.
Hammond
Adrienne
A
Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
Dertien
Janet
J
Colmer-Hamood
Jane A
JA
Griswold
John A
JA
Hamood
Abdul N
AN
D000818:Animals; D001422:Bacterial Adhesion / Q000187:drug effects / Q000502:physiology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002406:Catheterization, Peripheral; D002417:Cattle; D003470:Culture Media; D006801:Humans; D008855:Microscopy, Electron, Scanning; D018962:Phlebotomy; D010969:Plastics; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D012710:Serum Albumin, Bovine / Q000494:pharmacology
D003470:Culture Media; D010969:Plastics; D012710:Serum Albumin, Bovine