Comparison of survivability of Staphylococcus aureus and spores of Aspergillus niger on commonly used floor materials

Abstract

Background: The survivability of Staphylococcus aureus and spores of Aspergillus niger was compared on 5 common floor materials.

Methods: Floor materials were inoculated with a known concentration of S aureus and spores of A niger on day 0. Their survivability was measured on days, 2, 7, 14, and 28 by bulk rinsate method and enumerated using culture-based method.

Results: The difference in change of S aureus levels was statistically significant for all tested days (P < .001) for all floor materials. Vinyl composition tile (VCT) and porcelain tile (PT) had statistically similar survivability and differed statistically from carpets. On both VCT and PT, positive growth for S aureus occurred by day 2 (1-1.7 log₁₀), declined slightly (0.1 to -0.2 log₁₀) by day 7, and remained positive until day 28. However, S aureus was undetected by day 7 on both carpets. A niger spores were undetected on residential broadloom carpet and rubber-backed commercial carpet after day 2 but survived on VCT, PT, and wood until day 28.

Conclusions: Floor materials with hard and smooth surfaces, such as VCT and PT, can allow survival of S aureus and A niger for up to 4 weeks. It may imply that floor materials can play a major role in preserving microbial contaminants in the built environment.

Keywords: Aspergillus niger; Built environment; Carpet; Floor materials; Spore; Staphylococcus aureus; Survivability.