Northern Elephant Seals in danger from pathogenic and antimicrobial –resistant bacteria!

Stoddard, R. A., Atwill, E. R., Gulland, F. M. D., Miller, M. A., Dabritz, H. A., Paradies, D. M., Worcester, K. R., et al. (2008). Risk factors for infection with pathogenic and antimicrobial-resistant fecal bacteria in northern elephant seals in California. Public health reports Washington DC 1974, 123(3), 360-370. Association of Schools of Public Health.

Stoddard et al. took on a tricky experiment design. The aim of their study was: to identify potential risk factors in northern seals, which relate to increased odds of bacterial infection (Campybacter jejuni, Salmonella spp. Escherichia coli- antimicrobial resistant). The study took place off the cost of California (nice), 34 million inhabitants 72% of who are coastal residents. Pollution can enter the coastal waters from many different sources e.g. municipal, industrial and agricultural effluent, storm runoff, and sewage outlets. Most of these pollutants are transported into the ocean via rivers eventually.

The Centre for Disease and Control and Prevention, claim that water transported bacterial infections are diluted to half of the 3-5 billion cases of diarrhoea in the U.S. each year. CDCP reports also implicate that the bacteria under investigation in Stoddard et al. research are responsible for the majority of the infections. Direct pathogen exposure increase is not the only concern of their research, antimicrobial resistance strand influxes are also pivotal to their research.

The study took place from July 2003-2004. The study consisted of: 165 juvenile northern elephant seals from their natal beach and 196 juvenile seals that were stranded on the California coat. Stranded seals were sampled after 24-48 hrs. of being admitted to a sanctuary rescue centre. Bacteria were sampled from all study specimens and culture, antimicrobial analysis was carried out. The complexity to their design arose during analysis when calculating risk factor coefficients. They were obtained by using parameters: gender, weight, county of standing, month, human pop. Freshwater outflow and accumulative precipitation levels at regular prior intervals. The weather data that was used was not always reliable e.g. the confidence in the historical precipitation records were not always correct, due to equipment malfunction during documentation.

Their findings were:

· Odds of C jejuni and antimicrobial resistance of E.coli were higher in faeces of seals from sites of higher freshwater outflow.

· Odds of contracting salmonella spp. in faeces is 5.4 times greater of seals stranded in locations with low levels of 30 day cumulative precipitation.

· Odd of juvenile seals having antimicrobial resistant E.coli in its faeces increase substantially, in relation to corresponding increases of freshwater outflow. The same trend was found for C jejuni.

The authors concluded: juvenile northern elephant seals are contracting antimicrobial resistant faecal bacteria and pathogenic bacteria, which are most likely acquired from terrestrial river outflow. Therefore the terrestrial locations can impact the ecology of the marine environment, and the health of the animals and humans that rely on it. Demonstrating a critical need to deepening the understanding of the complexities of the ecology of the terrestrial/marine interface.

This research highlights the validity of keeping accurate weather records and records of effluence of pollution. This information is integral to producing models for understanding the feedback loops and mechanisms that are occurring. Due to this, this research is of significant importance. Studies like these may also highlight the complexities that may be occurring in other coastal regions and indicate further anthropogenic pollutant negative feedback relationships on both microbial community composition and acquired antimicrobial resistance. Further monitoring of just how prolific antimicrobial resistance is becoming in coastal waters would indicate the extent of this problem. Making this vital research.