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Swimming with Staphylococci at Waikiki
In Hawaii, the risk for developing infections at public swimming areas persists.
The closest I come to a regular religious experience is the surfing I do on Sunday mornings at “Rock Piles,” a body of water near Waikiki Beach that is famous for consistent waves but a risk of shallow coral when the tide is out.
I usually go with a few friends, including several internists, a psychiatrist and sometimes a cardiologist (who can assure me of medical care if needed). It would be nice to have a surgeon join us in case of injury, but they prefer more challenging surf and take risks far beyond my comfort level, even though one of them recently lost a toe to a safety cord.
We usually set out about 7:00 a.m. to get a parking space, to arrive before too many other surfers get there and to avoid the UV exposure of the midday sun. It is a wonderful and exhilarating experience and does have some religious elements as well, including the camaraderie of accompanying my friends to a local Starbucks to instill some caffeine, the observation of some of the local human fauna with limited attire and the telling of stories about how life was and should be.
Waterborne infections
When I started my sabbatical from clinical practice about seven years ago, I took up paddling with a team of six in an outrigger canoe but gave it up due to my aging back and bones. One of the things I heard about then was the infections that are related to paddling, especially in the Ala Wai canal, a dead-end dredged channel than empties runoff water into the ocean behind the string of hotels along Waikiki. I naturally wanted to know more, so I went to the literature and found articles of two decades ago by local infectious diseases specialists that described the association and studies by Roger Fujioka, a researcher in the oceanography department who documented Staphylococci he recovered from the water of Waikiki.
Fujioka’s laborious methods a decade ago demonstrated he could isolate up to 100 colony-forming units of Staphylococcus aureus from the aliquots of 100 mL of seawater he collected. I was impressed with this and the additional studies he did, which indicated the colony counts fell off dramatically at night and that there were virtually no Staphylococci recovered when the Ala Wai canal was sampled.
It soon became apparent that the Staphylococci were associated with bathers since no one swims in the Ala Wai and there were no S. aureus isolated at beaches where there were no bathers: something that I had previously found in Puget Sound as well, where the cold water is a deterrent to people as well as Staphylococci.
It seemed apparent that people were shedding their bacteria into the sea and that the environment was not conducive to their growth or persistence. My interest in this phenomenon was piqued, however, and led to repeating the studies which confirmed the presence of S. aureus and that it correlated with the number of bathers in the water at Waikiki. Along with the help of the molecular biology department of the medical school, we also found a remarkable number of varieties of clone types by spa typing; but this could be easily explained by the variety of visitors coming here to swim who contribute their organisms from places as varied as California, Iowa, New York, Europe and Asia. Some of the strains were resistant to methicillin but no more than expected from the usual asymptomatic population.
Further investigation
Further investigation of the microbiology of the ocean was surprising. I found good documentation that there were approximately 1 million bacteria per mL of ocean water, according to the findings of a PEW Foundation report. Most of these are not culturable and probably are waiting to be named after the investigators who can better characterize and fit them into some complex schema of life.
The majority of the ones we can easily identify are gram-negative, such as a remarkable variety of vibrios which vary with the changing environments and water conditions. Gram-positives are present, but most are coagulase-negative, although coagulase may not be a useful marker for pathogenicity for the species that normally inhabits the sea. Leptospirosis seems confined to the freshwaters of Hawaii, although it does make it out to occasionally infect surfers if there are heavy rains and run off into the ocean.
We have continued to investigate the S. aureus strains we have here, especially in light of the media hype and the Association for Professionals in Infection Control and Epidemiology report findings which stated that Hawaii has more patients with methicillin-resistant Staphylococcus aureus in the hospital than any other state. I am repeatedly contacted by anxious locals and pestered by the local media about gory cases that might possibly be related to recreational seawater exposure. The lawyers are also circulating like sharks about any cases that can be clearly connected to the seawater or the sewage spill into the Ala Wai canal, which occurred last year.
Risk for exposure
As part of our work, we have tried to connect actual exposure to seawater and S. aureus infections but have not been able to do so. The methodology is getting better with gene probes and surveillance systems. However, the association seems so low and the confounding factors so great, such as other sports injuries and staph infections without seawater exposure, that it is not clear there is an association. If there is, it is a very small one. The prospect of finding a significant link is a daunting one with a remarkable number of volunteers needed and an expense far beyond what the local health grantors will accept. The idea of establishing safe levels of Staphylococci, as is done for coliforms despite the modern sewage systems, is difficult. The idea of remediation would best be keeping the tourists out of the water: not a great idea from a merchant perspective and one that could hurt the local economy.
Another interest we have is in exploring the microbiology of the sea with the orientation of humans. We have found S. aureus can rarely be recovered from the nares of seals, although a few coagulase-negative strains can be. We have also found the coagulase-negative Staphylococci isolated from seawater are about as resistant to our usual antibiotics as the human isolates. We have not yet found any vancomycin-resistant Enterococcus but have not looked hard. We have also found an abundant array of prophages in our seawater, which could easily carry resistance and virulence factors that are not conducive to human wellness and habitation. What risk there is for incubating antibiotic resistance in the melting pot of microorganisms at Waikiki is of considerable interest, but minimal funding seems available. Perhaps the oceans are a breeding ground for new antimicrobials as well as resistance to them. Most new antibiotics seem derived from water of some sort. The potential for resistance and virulence mechanisms from this enormous test tube seems to suggest it could be a major problem and source of information.
So what am I going to do next Sunday? Go swimming and surfing at Waikiki and thank God and Neptune for the opportunity to do so. It is probably far safer than the hospitals where I make my rounds – and a lot more fun as well. My only concern is whether I am shedding my normal flora into the sea, where it may affect the creatures that naturally reside there.
I am happy to take all the risks and am also hopeful that the exploration of the sea in regard to human health will be systematically explored in the future.
For a different “take” on the Staphylococcus aureus problems, here is a contribution from one of our editorial advisory board members, Dr. Alan Tice, who obviously takes advantage of some of the local attractions.
– Theodore Eickhoff, MD
Chief Medical Editor
For more information:
- Chang W, Pien F. Marine-acquired infections: hazards of the ocean environment. Postgrad Med. 1986;80:30-32,37,41.
- Charoenca N, Fujioka R. Association of staphylococcal skin infections and swimming. Wat Sci Tech. 1995;31:11-17.
- Tice A, Fowler T, Fukioka R. Staphylococcus aureus in the recreational seawaters of Hawaii. #534. Poster presented at: the 2004 Meeting of the Infectious Diseases Society of America; Sept. 29-Oct. 2, 2004; Boston.
- PEW report. http://www.pewoceans.org.