TABLE 3

Optimal in vitro growth conditions for biofilm formation of microorganisms isolated from two Canadian hospitals

Organism typeaBiofilm mediumbIncubation
conditionsc
Gram-positive bacteria
    S. epidermidis
        ONMH II + 2% NaCl48 h at 37°C
        SKM9 + 0.5% glucose, 0.5% CAA24 h at 37°C
    S. aureus
        ONTSB + 1.5% glucose24 h at 37°C
        Methicillin resistant
            ONBHI + 2% glucose, 4% NaCl48 h at 37°C
            SKBHI + 1% glucose, 4% NaCl24 h at 37°C
    E. faecalis
        ONTSB/BHI + 1% glucose, 4% NaCl48 h at 37°C
        Vancomycin resistant (SK)TSB + 2% glucose, 4% NaCl48 h at 37°C
Gram-negative bacteria
    Escherichia coli
        ONM9 + 0.2% glucose, 0.2% CAA48 h at 28°C
        SKM63 + 0.3% glucose, 0.5% CAA48 h at 28°C
    Stenotrophomonas maltophilia (ON)TSB + 0.5% glucose48 h at 37°C
    Pseudomonas aeruginosa (SK)LB24 h at 37°C
    Enterobacter agglomerans (ON)M9 + 0.1% glucose, 1.0% CAA48 h at 28°C
    Serratia marcescens (SK)TSB48 h at 28°C
    Proteus mirabilis (ON)M63 + 0.25% glucose, 0.5% CAA24 h at 37°C
    Klebsiella pneumoniae (SK)M9 + 0.25% glucose, 0.5% CAA24 h at 37°C
Fungi
    Candida albicans (ON or SK)YPD/2% glucose24 h at 37°C
    Candida glabrata (ON or SK)YNB48 h at 28°C
Control bacteria
    Salmonella enterica serovar Typhimurium1/2 LB no salt + 40 μM 2,2-dipyridyl24 h at 37°C
  • a Microorganisms were obtained from the Southlake Regional Health Centre in Ontario (ON) or the Royal University Hospital in Saskatchewan (SK).

  • b MH II, Mueller-Hinton II broth; M9, M9 minimal medium; CAA, Casamino Acids; TSB, tryptic soy broth; BHI, brain heart infusion; M63, M63 minimal medium; LB, lysogeny broth; YPD/2% glucose, 1% yeast extract and 2% peptone supplemented with 2% glucose; YNB, yeast nitrogen base.

  • c For bacterial isolates, slight rocking was applied during growth; for fungal isolates, orbital shaking at 200 rpm was applied, which improved overall biofilm formation.