Staphylococcus aureus biofilm formation at the physiologic glucose concentration depends on the S. aureus lineage.
BACKGROUND
Since bacteria embedded in biofilms are far more difficult to eradicate than planktonic infections, it would be useful to know whether certain Staphylococcus aureus lineages are especially involved in strong biofilm formation. For this reason, in vitro biofilm formation of 228 clinical S. aureus isolates of distinct clonal lineages was investigated.


RESULTS
At 0.1% glucose, more than 60% of the S. aureus strains associated with multilocus sequence typing (MLST) clonal complex (CC)8 produced large amounts of biomass, compared to 0-7% for various other clonal lineages. Additionally, S. aureus bloodstream isolates associated with MLST CC8 and CC7 had similar biofilm forming capacities as their commensal counterparts. Furthermore, strong biofilm formation could not be attributed to a specific accessory gene regulator (agr) genotype, as suggested previously. The agr genotypes were strictly associated with the clonal lineages. Moreover, strong biofilm formation was not related to slime formation. Congo red agar (CRA) screening is therefore not useful as a qualitative screening method for biofilm formation.


CONCLUSIONS
The adherence to polystyrene surfaces under physiologic glucose concentration (0.1%) was dependent on the clonal lineage. Strains associated with MLST CC8 were markedly more often classified as strong biofilm former at glucose concentrations of 0%, 0.1% and 0.25%. The present study reveals that the MLST CC8 associated genetic background was a predisposing factor for strong biofilm formation in vitro, under all tested glucose concentrations.
Department of Medical Microbiology, Maastricht University Medical Center, Maastricht, The Netherlands. S.Croes@mumc.nl
Sander
S
Croes
Ruud H
RH
Deurenberg
Marie-Louise L
ML
Boumans
Patrick S
PS
Beisser
Cees
C
Neef
Ellen E
EE
Stobberingh
D001422:Bacterial Adhesion; D015373:Bacterial Typing Techniques; D018441:Biofilms; D005838:Genotype; D005947:Glucose / Q000502:physiology*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D010641:Phenotype
D005947:Glucose