Enterococci, a common fecal indicator, and Staphylococcus aureus, a common skin pathogen, can be shed by bathers affecting the quality of recreational waters and resulting in possible human health impacts. Due to limited information available concerning human shedding of these microbes, this study focused on estimating the amounts of enterococci and S. aureus shed by bathers directly off their skin and indirectly via sand adhered to skin. Two sets of experiments were conducted at a marine beach located in Miami-Dade County, Florida. The first study, referred to as the "large pool" study, involved 10 volunteers who immersed their bodies in 4700 L during four 15 min cycles with exposure to beach sand in cycles 3 and 4. The "small pool" study involved 10 volunteers who were exposed to beach sand for 30 min before they individually entered a small tub. After each individual was rinsed with off-shore marine water, sand and rinse water were collected and analyzed for enterococci. Results from the "large pool" study showed that bathers shed concentrations of enterococci and S. aureus on the order of 6 × 10 5 and 6 × 10 6 colony forming units (CFU) per person in the first 15 min exposure period, respectively. Significant reductions in the bacteria shed per bather (50% reductions for S. aureus and 40% for enterococci) were observed in the subsequent bathing cycles. The "small pool" study results indicated that the enterococci contribution from sand adhered to skin was small (about 2% of the total) in comparison with the amount shed directly from the bodies of the volunteers. Results indicated that bathers transport significant amounts of enterococci and S. aureus to the water column, and thus human microbial bathing load should be considered as a nonpoint source when designing recreational water quality models.

The rapid chemical analysis of individual cells is an analytical capability that will profoundly impact many fields including bioaerosol detection for biodefense and cellular diagnostics for clinical medicine. This article describes a mass spectrometry-based analytical technique for the real-time and reagentless characterization of individual airborne cells without sample preparation. We characterize the mass spectral signature of individual Bacillus spores and demonstrate the ability to distinguish two Bacillus spore species, B. thuringiensis and B.atrophaeus, from one another very accurately and from the other biological and nonbiological background materials tested with no false positives at a sensitivity of 92%. This example demonstrates that the chemical differences between these two Bacillus spore species are consistently and easily detected within single cells in seconds.

No abstract