Surface charge influences enterococcal prevalence in mixed-species biofilms.
OBJECTIVE
To study the influence of 15 microbial isolates on the prevalence of charge-heterogeneous and charge-homogeneous Enterococcus faecalis strains, all isolated from biliary stents, in mixed-species biofilms.


RESULTS
Six Enterococcus faecalis strains were paired with 15 other microbial isolates to form mixed-species biofilms in a microtitre plate assay. Charge-heterogeneous Enterococcus faecalis strains display two subpopulations with different surface charges, expressed as a biomodal zeta potential distribution. It was found that, in general, the prevalence of the charge-heterogeneous, biofilm forming Enterococcus faecalis was reduced in mixed-species biofilms. The prevalence of charge-homogeneous, nonbiofilm-forming Enterococcus faecalis strains was increased only in the presence of Citrobacter freundii BS5126, Stenotrophomonas malthophilia BS937, and Candida lusitaniae BS8256, all of which introduced sizeable charge heterogeneity in the mixed microbial population.


CONCLUSIONS
Charge-homogeneous Enterococcus faecalis strains are stimulated to form biofilm only by the presence of another microbial species with a considerably less negative zeta potential, thereby creating a charge-heterogeneous microbial population.


CONCLUSIONS
Enterococcus faecalis is one of the predominant species isolated from mixed-species biofilms in clogged biliary stents. The current study shows how charge-homogeneous Enterococcus faecalis strains form more biofilm in the presence of other microbial species.
van Merode
A E J
AE
Department of Biomedical Engineering, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. a.e.j.van.merode@med.umcg.nl
Pothoven
D C
DC
van der Mei
H C
HC
Busscher
H J
HJ
Krom
B P
BP
D001419:Bacteria / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification; D001422:Bacterial Adhesion / Q000502:physiology*; D001652:Bile Ducts / Q000382:microbiology* / Q000601:surgery; D018441:Biofilms / Q000254:growth & development*; D004866:Equipment Contamination; D055672:Static Electricity; D015607:Stents / Q000382:microbiology*