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Man loses leg to flesh-eating disease caused by very rare fungus infection

A man came close to death and had to have his leg amputated after contracting a “flesh-eating” disease resulting from an “extremely rare” fungal infection.

The individual in his 60s, who was a machinery operator, went to the hospital in Queensland, Australia, with a skin tear to his left calf, a BMJ Case Report said earlier this month. The man said he had injured his leg on a caravan door.

Doctors eventually diagnosed him with necrotizing fasciitis—a rapidly progressing soft tissue infection that can potentially be fatal.

Necrotizing fasciitis is already rare, but is primarily caused by certain types of bacteria, which move rapidly through the body, attacking the skin and soft tissue, according to the Centers for Disease Control and Prevention (CDC.)

The name of the disease refers to the fact that it is characterized by the death of soft tissue—for example those that surround muscles, nerves, fat and blood vessels—which, in severe cases, can result in the shutting down of organs.

But in “extremely rare” cases—as occurred with the man in his 60s—a fungal infection can be the underlying causative agent of necrotizing fasciitis, the authors of the BMJ paper wrote.

An artist’s illustration of a mold that causes the mucormycosis fungal disease. A man had to have his leg amputated after contracting a “flesh-eating” disease resulting from an “extremely rare” fungal infection.

When the man went to his local hospital his leg wound was tender and warm. Doctors treated the injured leg, but his condition deteriorated and he developed a fever, forcing him to be transferred to a larger, regional hospital for a few days.

There, the man suffered kidney failure as well as sepsis—a potentially life-threatening condition occurring when the body produces an immune response to an infection that damages its own tissues, causing organs to function poorly and abnormally. He was then transferred to another hospital where doctors began treating him for a necrotizing soft tissue infection.

According to the BMJ report, doctors “debrided” a significant part of the man’s lower leg. Debridement is the medical term for the removal of dead, damaged or infected tissue—a procedure that is conducted in an attempt to help the remaining healthy tissue in a given area to heal. Further debridement was required, with the man undergoing three further operating procedures over the subsequent two weeks.

But despite the fact that doctors had removed adequate margins of healthy tissue around the area of infection—leaving a large chunk of the man’s leg missing right down to the bone—they continued to find ongoing evidence of soft tissue necrosis. As a result, a decision was made with the man’s next of kin to conduct an amputation of the infected leg above the knee.

After amputating the leg, doctors treated the wound with a technique known as negative pressure wound therapy. This method involves drawing out fluid and infected tissue from a wound to help it heal. A special dressing is sealed over the wound and attached to a vacuum pump.

However, during a procedure to replace the dressing, which required a trip to the operating room, the man suffered a hyperkalemic cardiac arrest after being placed under general anesthetic. Hyperkalemia is an elevated level of potassium in the blood, which can cause an abnormal heart rhythm, potentially resulting in cardiac arrest and death.

Fortunately, doctors managed to resuscitate the man, who returned to the intensive care unit (ICU). During his time there, doctors had to manage his kidney failure, as well as other complications such as acute anemia (an abrupt drop in red blood cells that can also be life-threatening in severe cases), coagulopathy (a bleeding disorder in which the blood’s ability to form clots is impaired), and multiple organ failure.

Doctors also conducted several lab tests of the patient, which eventually revealed that he had mucormycosis—a serious, but rare fungal infection caused by a group of molds called mucormycetes. The infection was “angioinvasive” in nature, meaning it had infiltrated the blood vessels.

With this knowledge in hand, medics began treating the man with an anti-fungal medication called amphotericin B for seven days. His condition improved and he was eventually moved to ward-level care having spent a month in the ICU.

During his time in the hospital, doctors had sent fungal samples to the National Mycology Reference Centre at the University of Adelaide, Australia. There, scientists identified the fungus responsible for the man’s infection as the species Saksenaea vasiformis.

The man was eventually discharged home after spending some time at his local hospital for further rehabilitation.

He can walk now with a prosthetic leg and the authors of the BMJ study said he is “thankful” for the quality of life that he has been left with. The amputation wound has completely healed and he has suffered no other long-term consequences from his severe fungal infection.

Different Types of Necrotizing Fasciitis

Necrotizing fasciitis is broadly classified into four types (I-IV) with I and II being the most common. Types I-III are caused by various types of bacteria, whereas type IV involves fungal pathogens. In the fungal cases, a group known as the zygomycetes or the genus (group of species) Candida are usually responsible.

The zygomycetes are subdivided into two subgroups—Mucorales and Entomophthorale. Mucorales fungi are the primary cause of mucormycosis, with S. vasiformis being the sixth most prevalent species of this subgroup.

In this case, the patient in the study survived the disease, which is rare for angioinvasive mucormycosis. This infection has a “very high” mortality rate, according to the authors.

One review of the scientific literature showed that infection with S. vasiformis and very similar related species led to death in 17 out of 46 patients.

Infections with these species are usually reported in individuals living in warm climates—as was the case with the patient in the BMJ study who lived in rural Queensland. In most cases identified in the review, the fungus, which is extremely fast growing, infected the lower limbs first.

The molds that cause mucormycosis are found throughout the environment, primarily in the soil and decaying organic matter, but also in the air.

People can become infected by inhaling fungal spores, or via a cut, burn, or other type of skin injury. Mucormycosis is not contagious and cannot be spread from one person to another. These fungi are not harmful to most people, primarily affecting individuals who have weakened immune systems or other health problems.

The man in the BMJ study had a history of heart disease, type 2 diabetes and other health conditions, and was taking several medications. His survival in this case can be attributed to prompt treatment once the causative pathogen was discovered accompanied by the appropriate anti-fungal therapy, debridement and amputation, according to the study.

The authors in the report said his case highlights the importance for doctors of considering rare type IV causes of necrotizing fasciitis—specifically mucormycosis—in patients who do not respond to early debridement and appropriate administration of antibiotics.

“Although mucormycosis is a rare occurrence, it carries a high mortality if left to become angioinvasive and so awareness of this condition is important,” the authors wrote.

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