Bather-related microbial and yeast populations in sand and seawater

Abstract The presence of bacteria and yeasts in water and wet sand was correlated with the number of swimmers present on the beach. Water and wet sand samples were collected from two beaches in summer and winter and the number of swimmers present on the beach was counted. Microbiological tests for the counts of coliforms, faecal coliforms, enterococci, S. aureus , yeasts and moulds were carried out. Water and sand samples were very low in indicator organisms of faecal pollution. Human species of yeasts were are present in water and sand samples of both sites. S. aureus was isolated from water and sand samples twice in winter. In summer, S. aureus was recovered more often from sand than from water samples in both sites. Water and samples in both sites contained significantly more S. aureus in summer than in winter samples. In summer, more yeasts of human origin were present in sand samples while less in water samples. A significant correlation appears between the number of swimmers present on the beach and S. aureus counts in water samples; the correlation is stronger at the more popular beach. In sand samples S. aureus counts correlate with the number of swimmers present on the beach only at the more popular beach. Yeasts of human origin correlate with the number of swimmers on the more popular beach, both in water and sand samples.