Why I Don’t Eat Raw Oysters: What The Emerging Literature Reveals About Infectious Diseases And Contaminated Food

The more I read the infectious disease literature, the more limited my diet becomes. It seems that new reports of contaminated food are published regularly. It gets to a point where you do not know what you should and should not eat.

I have always been wary of raw foods and rarely eat sushi. This was especially the case after an article was published in Clinical Infectious Diseases a number of years ago complete with pictures of the worm coughed up by a patient who ate salmon sushi.1 (I apologize to those of you who love to eat sushi. It’s just not for me.)

Even cooked foods I thought would be safe are suspect. Take, for example, the report I read back in 1998 of a botulism outbreak from baked potatoes that were wrapped in foil.2 More recently, there has been the incredibly deadly Shiga toxin producing E. coli outbreak centered in Hamburg and Lubeck, Germany.3 The mystery fortunately got solved one week before my wife and I visited both of those wonderful cities on vacation.

If these examples were not enough to cause consternation, consider two papers published in the July 15, 2011 issue of the Journal of Infectious Diseases. This first is an editorial commentary by Daniel Bausch, MD, MPH: “Ebola virus as a foodborne pathogen? Cause for consideration, but not panic.”4 Ebola virus? That deadly organism from Africa that kills 90 percent of all whom it infects? In food? Fortunately, there really is no reason for panic. The author discusses how a variant of the virus, known as the Reston EBOV, which is not known to be pathogenic in humans, has been found in pigs in the Philippines … but still.

A second article in the same issue by Behravesh and co-workers is an analysis of the Foodborne Diseases Active Surveillance Network (FoodNet).5 Fortunately, death from foodborne illness remains relatively rare, reportedly occurring in just 0.5 percent of cases with most being in adults over 65. Salmonella and Listeria were the most common causes followed closely by Vibrio.

I have always been fascinated by infections caused by various Vibrio species found primarily in raw oysters. Early in my infectious disease career, I attended the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), one of the great antibiotic and microbiology meetings, when it was in New Orleans in 1986. Three years later, Lowry and colleagues published a study in the Journal of Infectious Diseases that reported on Vibrio gastroenteritis in attendees of the meeting who ingested raw oysters.6 The authors found that 12 percent of respondents reported diarrhea and the risk was significantly higher in those who ate raw or cooked oysters. Furthermore, they found that cultures of raw and cooked seafood at local restaurants yielded five different species of Vibrio.

A PubMed search reveals outbreaks of this type reported with oyster consumption from all over the world including different locales in the United States. Fortunately, I seem to remember Louisiana State University doing a study and finding that the use of Tabasco sauce was protective against infection.7

By this point, you may be wondering what any of this has to do with the lower extremity. Vibrio species, in particular V. vulnificus, has the ability to cause rapidly progressive, frequently fatal necrotizing infections of the lower extremity in two ways. First, direct inoculation of the organism into the soft tissues has been reported when marine water comes in contact with an open wound or if someone cuts themselves on a contaminated item in the marine environment. (Now, I not only have to watch what I eat but I avoid swimming in the ocean too.)

The more common and deadly infection occurs after a patient ingests infected seafood and develops Vibrio bacteremia and septicemia, that subsequently cause severe necrotizing skin and soft tissue infections. A recent review by Horseman and colleagues in the International Journal of Infectious Diseases reports a mortality rate exceeding 50 percent.8 The authors opine that the antimicrobial regimen of choice is doxycycline (Vibramycin, Pfizer) combined with ceftazidime (Fortaz, GlaxoSmithKline) and aggressive surgical debridement.

Another study from just this year published by Tsai and co-workers in the American Journal of Bone and Joint Surgery compares necrotizing infections by V. vulnificus and methicillin resistant Staphylococcus aureus.9 The authors found that the Vibrio infection progresses more rapidly and can be more deadly. They declared it to be a “surgical emergency.”

The photograph on the left came to me from Desmond Bell, DPM, CWS, a top podiatric wound authority and co-founder and Executive Director of the Save A Leg, Save a Life Foundation (SALSAL, http://www.savealegsavealife.org/) I have known Des since his days as one of my students and have lectured a number of times at the SALSAL scientific meeting, which is being held this year in Orlando from October 27-30. He received the photo from his colleague, Michael Baxley, MD. The photograph shows a foot wound in a patient who had developed Vibrio sepsis after ingesting oysters in coastal Alabama. The patient fortunately survived the sepsis but now has skin wounds of varying severity on his hands, legs and feet.

Perhaps I should have written this post earlier in the summer season before many of you went on vacation to the seashore. Then again, maybe not.

Editor’s note: This blog was originally published at http://www.leinfections.com/infections/why-i-don%E2%80%99t-eat-raw-oysters/ and has been adapted with permission from Warren Joseph, DPM, FIDSA, and Data Trace Publishing Company. For more information about the Handbook of Lower Extremity Infections, visit www.leinfections.com/ .

References

1. Zvejnieks PA, Lichtenstein KA, Koneman EW. Photo quiz II. Luminal anisakidosis due to Pseudoterranova decipiens. Clin Infect Dis. 1998; 26(5):1085.

2. Angulo FJ, Getz J, Taylor JP, et al. A large outbreak of botulism: the hazardous baked potato. J Infect Dis. 1998; 178(1):172-7.

3. Frank C, Werber D, Cramer JP, et al. Epidemic profile of Shiga toxin-producing Escherichia coli O104:H4 outbreak in Germany: preliminary report. N Engl J Med. 2011 June 22. Epub ahead of print.

4. Bausch DG. Ebola virus as a foodborne pathogen? Cause for consideration, but not panic. J Infect Dis. 2011; 204(2):179-81.

5. Barton Behravesh, Jones TF, Vugia DJ, et al. Deaths associated with bacterial pathogens transmitted commonly through food. J Infect Dis. 2011; 204(2):263-7.

6. Lowry PW, McFarland LM, Peltier BH, et al. Vibrio gastroenteritis in Louisiana: a prospective study among attendees of a scientific congress in New Orleans. J Infect Dis. 1989; 160(6):978-84.

7. Altman LK. What’s sauce for the oyster may also keep the doctor away. New York Times, Oct. 19, 1993. Available at http://www.nytimes.com/1993/10/19/health/what-s-sauce-for-the-oyster-may... .

8. Horseman MA, Surani S. A comprehensive review of Vibrio vulnificus: an important cause of sepsis and skin and soft-tissue infection. Int J Infect Dis. 2011; 15(3):157-66.

9. Tsai YH, Wen-Wei Hsu R, Huang KC, Huang TJ. Comparison of necrotizing fasciitis and sepsis caused by Vibrio vulnificus and Staphylococcus aureus. J Bone Joint Surg Am. 2011; 93(3):278-84.



Jim DiNovis DPMsays: September 19, 2011 at 1:52 pm

I recently discussed Vibrio species infections with the mother of a patient. Her daughter developed a Mycobacterium marinum infection after a barnacle scrape in the waters off Long Island, New York. She was treated by ID with Rifampin/TMP and then Rifampin/Doxycycline over a six week period as I recall.

Another patient related a story of his neighbor spending over a month in the hospital with an intestinal infection after catching and eating soup from blue claw crabs caught from the mud of a local tidal creek. I have no information on the causative species.

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