Environmental Factor, November 2009, National Institute of Environmental Health Sciences
Oceans Center Study Offers Caveat for Beachgoers
By Eddy Ball
By combining solid research and relationship building, the National Science Foundation (NSF)-NIEHS Center for Oceans and Human Health (COHH) (http://www.niehs.nih.gov/research/supported/dert/programs/oceans/) at the University of Miami and its collaborators are taking their science to the people on the beaches of America - and highlighting an under-appreciated human source of exposure to bacteria, including the potentially deadly methicillin-resistant Staphylococcus aureus (MRSA). New research findings from investigators at the Miami COHH program and their network of collaborators are informing a cautionary message to beachgoers and beach managers about pathways for spreading of bacterial contamination by humans.
A new study (http://www.ncbi.nlm.nih.gov/pubmed/19646730?ordinalpos=8&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) authored by Samir M. Elmir, PE, Ph.D., Florida Department of Health, Miami COHH Principal Investigator Lora Fleming, M.D., Ph.D., and colleagues from the Florida Department of Health, University of Miami, National Oceanic and Atmospheric Administration (NOAA) and the Centers for Disease Control and Prevention (CDC) has been published in the October issue of Water Research. The group's research quantified the extent of shedding of fecal bacteria by adults and toddlers.
The group's study was the first ever evaluation of bacterial shedding from toddlers. It was also the first study of bacterial shedding to introduce additional advanced methods of fecal indicator bacterial analysis - chromogenic substrate (CS) and quantitative polymerase chain reaction (qPCR) - for purposes of supplementing the standard culture-based membrane filtration (MF) method and validating the far more rapid advanced methods within the study. The field experimental design was based upon a prior study, which also allowed for between-study validation.
Researchers gathered their human data from 20 adults and 14 diapered toddlers who dipped into large and small pools, respectively, set up on a beach in Miami for measurement of direct shedding of bacteria during bathing cycles. The adults were evaluated during 4 cycles of bathing, 2 cycles with no sand contact followed by 2 cycles with sand exposure. The children in their diapers played in the sand on the beach for 15 to 30 minutes before entering an individual small pool for 1 cycle of water exposure.
Surprisingly, the researchers found that adults and toddlers shed approximately the same amounts of bacteria into the water. In the adults, the effect of sand exposure had a relatively small contribution to this bacterial shedding until their bodies were washed several times. Furthermore, the sand contribution was proportional to the body surface area, with adults carrying more sand than children back into the water.
"This study demonstrates that humans of all ages are one of many sources of bacteria in recreational marine waters. Furthermore, these data support the universal recommendation of bathing before entering bodies of water to decrease the individual's bacterial shedding contribution," Fleming said of the study. "It's gratifying to see our findings translated through our University of Miami OHH collaborations with the Florida Department of Health, NOAA, CDC and other partners to help get the word out to beachgoers."
Along with the Miami COHH at the Rosenstiel School of Marine and Atmospheric Sciences of the University of Miami, collaborators on the study included scientists and public health specialists affiliated with the Florida Department of Health (FDOH), the NOAA Atlantic Oceanographic and Meteorological Laboratory, the Centers for Disease Control and Prevention (CDC), the University of Illinois, University of Miami Department of Civil, Architectural and Environmental Engineering, and the University of Miami Miller School of Medicine.
Citation: Elmir SM, Shibata T, Solo-Gabriele HM, Sinigalliano CD, Gidley ML, Miller G, Plano LR, Kish J, Withum K, Fleming LE. (http://www.ncbi.nlm.nih.gov/pubmed/19646730?ordinalpos=8&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) 2009. Quantitative evaluation of enterococci and Bacteroidales released by adults and toddlers in marine water. Water Res 43(18):4610-4616. Epub ahead of print.