|Slime production by Staphylococcus epidermidis.
Negative - left and positive - right.
Some Staphylococcus strains are able to produce an exopolysaccharides film (slime) which is responsible for bacterial adherence to
various surfaces like culture tubes, intravenous catheters and other medical devices, including even contact lenses. Most notable
species involved are Staphylococcus epidermidis and Staphylococcus aureus, although this is not a constant character inside
species. The slime production is considered to be a virulence factor. Slime-production strains seem to have a higher colonization
capacity and an increased antibiotic resistance.
MEDIA & REAGENTS
Recommended medium for slime production is Trypticase Soy Broth (TSB)
supplemented with glucose 0.25% wt/vol. Other media like BHI broth, Todd-Hewitt
broth, Brucella broth, Mueller Hinton broth, Sucrose broth, don't support slime
production or give variable results. Slime production requires the presence of
Casamino Acids (from TSB) and glucose, other sugars giving negative results.
Use safranin, trypan blue or alcian blue for staining.
Inoculate a glass or polystirene tube containing 5 ml of TSB supplemented with
glucose and incubate at 37 ºC for 24-48h.
Remove the content of the tube and rinse with distilled water 2-3 times (admin note).
Stain the tube with 0.25% safranin solution (or trypan blue).
A stained, adherent film on the surface of the tube is considered slime production.
Ring formation on medium surface should not be considered slime production.
There is no significant difference in slime production and adherence between glass or polystirene tubes.
1. Christensen GD, Simpson WA, Bisno AL, Beachey EH. Adherence of slime-producing strains of Staphylococcus epidermidis to
smooth surfaces. Infect Immun. 1982 Jul;37(1):318-26.
2. Catalanotti P, Lanza M, Del Prete A, Lucido M, Catania MR, Gallè F, Boggia D, Perfetto B, Rossano F. Slime-producing
Staphylococcus epidermidis and S. aureus in acute bacterial conjunctivitis in soft contact lens wearers. New Microbiol. 2005 Oct;
28(4) : 345-54.
3. Arslan S, Ozkardes F. Slime production and antibiotic susceptibility in staphylococci isolated from clinical samples. Mem Inst
Oswaldo Cruz. 2007 Feb;102(1):29-33.
(c) Costin Stoica