Biofilm Longevity Assessment Of E. Coli, S. Aureus, And C. Albicans In Nonnutritive Phosphate Buffered Saline
Joseph Knue1, Kan Lam1, Sarah Korn1, Kathleen Marcos2, Anthony McElwain1, Paul Attar1.
1BRIDGE PTS, San Antonio, TX, USA, 2UIW School of Osteopathic Medicine, San Antonio, TX, USA.
BACKGROUND - A growing body of evidence acknowledges the presence of microbial biofilms in human, chronic wounds. As such, the modified Robbins’ device remains an important tool in the study of biofilms, and is routinely used to assess the antimicrobial properties of novel agents on biofilms. Therefore, it is necessary to fully understand the natural lifespan of biofilms cultured using this testing system in order to differentiate between biofilm reduction caused by nutrient depletion vs exposure to anti-biofilm agents. METHODS - We assessed the longevity of three microbes (Escherichia coli, Staphylococcus aureus, and Candida albicans) in nonnutritive phosphate buffered saline (PBS) incubated in 6-port static testing devices. The biofilms were established in a modified Robbins’ device on PVC plastic sampling coupons. After 22 hours incubation at 37°C ± 3°C in half strength Tryptic Soy Broth (TSB; bacterial test systems) or half strength Yeast Dextrose Broth (YD/B; eukaryotic test system) circulating at 60 mL/hour, via a peristaltic pump, the sampling coupons were transferred from the modified Robbins’ device to a 6-port static sampling device filled with PBS. Coupons were then sampled to identify the concentration of viable microbes remaining on the coupon. RESULTS - At 7 days, log reductions in recoverable colony forming units were 5, 2, and 0.5 logs for E. coli, S. aureus, and C. albicans, respectively. CONCLUSIONS - These results show the importance of testing biofilm survival independent of test articles since there is a large range in biofilm longevity for different microbial species.
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