(CNN) -- It all started simply enough: A 31-year-old man went to get a tattoo on his right leg. Beneath an illustration of a cross and hands in prayer, the words "Jesus is my life" were written in cursive.
As tattoo artists will tell you, there are some critically important rules to follow in the hours and days after getting inked. Most important: keeping your new body art clean and covered while the skin has a heightened susceptibility to bacterial infection.
Every time a tattoo gun pierces your skin, the needle is opening a wound -- and another pathway by which germs can enter your body. The larger the tattoo, the more you increase your risk of possible infection.
After removing the original bandage and gently cleaning a new tattoo, the conventional advice is to apply antibacterial ointment for protection. Continue doing this multiple times a day for the next few days, until skin has ample time to heal.
The No. 1 thing to avoid while a tattoo heals is soaking it. That means quick showers, no baths and certainly no swimming. Experts warn to avoid prolonged exposure to potentially dirty water while your skin repairs itself. And that's where the story of the 31-year-old man takes a turn for the worse.
A report published last week in BMJ Case Reports, a prominent peer-reviewed medical journal, reveals only that the subject was a Latino man living in Texas. In a typical case study, patients are referred to by their initials. In this case, what happened was so rare, the authors declined to provide even that, to prevent anyone from figuring out his identity.
Five days after getting his tattoo, the man decided to go for a swim in the Gulf of Mexico. Just three days after that, he was admitted to Parkland Memorial Hospital in Dallas with severe pain in both of his legs and feet. His symptoms included a fever, chills and redness around his tattoo and elsewhere on his legs.
"A lot of our patients, when they come to our institution, come in sick -- and he was certainly among the sicker of the patients that we've had come in," said Dr. Nicholas Hendren, an internal medicine resident at University of Texas Southwestern Medical Center and lead author of the report. "He said he had a lot of pain in [his right leg]. That, of course, drew our attention right away.
"Within a few hours, things had progressed pretty quickly," he said. "There's darkening skin changes, more bruising, more discoloration, what we call bullae -- or mounds of fluid that were starting to collect in his legs -- which, of course, is very alarming to anyone, as it was to us.
"He was already in the early stages of septic shock, and his kidneys had already had some injury," Hendren said. "Very quickly, his septic shock progressed from ... early stages to severe stages very rapidly, within 12 hours or so, which is typical for this type of infection."
To make matters worse, the man had chronic liver disease from drinking six 12-ounce beers a day. He was immediately placed on a ventilator to help him breathe and given potent antibiotics.
The man tested positive for Vibrio vulnificus, a bacterium commonly found in coastal ocean water. The CDC estimates that this infection, called vibriosis, causes 80,000 illnesses and 100 deaths every year in the United States. The strongest risk factors are liver disease, cancer, diabetes, HIV and thalassemia, a rare blood disorder.
"In the USA, most serious infections appear to occur with the ingestion of raw oysters along the Gulf Coast, as nearly all oysters are reported to harbor V. vulnificus during the summer months and 95% of cases were related to raw oyster ingestion," according to the report.
Most of the time, the only symptoms someone will experience are vomiting and diarrhea, according to Hendren. Most healthy people don't end up in the hospital, he said, because their immune system is strong enough to fight the infection.
But "Infections can also occur with exposure of open wounds to contaminated salt or brackish water; however, this represents an uncommon mechanism of infection," according to the report.
Hendren never got the opportunity to ask the patient directly whether he was aware of the advice against swimming soon after getting a tattoo but said the man and his family were unaware of how a serious infection can progress so quickly.
For the next few weeks, the man was kept largely sedated. After initial pessimism about the man's prognosis, Hendren and his colleagues became cautiously optimistic. The patient was removed from the breathing machine 18 days after being admitted to the hospital and began "aggressive rehabilitation."
Over the next month, however, the man's condition slowly began to worsen. About two months after he was first admitted to the hospital, he died of septic shock.
"For patients who are healthy, this organism very rarely infects people," Hendren said. "If they are infected, most people do fine and essentially never present to the hospital. But in patients who do have liver disease, they're susceptible to much more infection."
Since most infections are the result of eating raw oysters, Hendren stressed the only way to kill the bacteria is by cooking them. People with liver disease or iron disorders should never eat raw oysters because they're at such high risk for these infections, he said.
Hendren said the message isn't that people shouldn't get tattoos.
"It's if you choose to get a tattoo, do it safely, do it through a licensed place, and make sure you take care of the wound and treat it like any other wound," he said. "That's important."
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