Microbiology
Summary
Mucor and Rhizopus are opportunistic fungi that cause mucormycosis. These infections predominantly impact immunocompromised individuals, especially those with conditions like leukemia, neutropenia, and diabetes. Entry into the body commonly results from spore inhalation, with the fungi thriving in blood vessel walls, especially in settings with elevated glucose and ketones, as seen in diabetic ketoacidosis (DKA).
A defining trait of these fungi is their non-septate hyphae displaying wide-angle branching. Once inside the body, the fungi can travel through the blood vessels, piercing the cribriform plate of the skull to access the brain. Such an invasion can lead to rhinocerebral mucormycosis and, in advanced stages, frontal cortex abscesses resulting in tissue necrosis. A notable symptom is a black eschar visible in the nasal cavity and on the face. The recommended treatment approach combines surgical debridement to excise necrotic tissue and the administration of the antifungal agent, amphotericin B.
Lesson Outline
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FAQs
Mucor and Rhizopus belong to the group Mucormycetes, a class of fungi responsible for causing the severe infection known as mucormycosis. They are significant in medical studies because they are commonly associated with high morbidity and mortality rates, particularly in immunocompromised patients.
Immunocompromised patients, such as those with poorly controlled diabetes, leukemia, lymphoma, transplant recipients or those with HIV/AIDS are at increased risk for mucormycosis. This is because their bodies' immune systems are not equipped to effectively fight against these types of fungal infections. Their conditions often create an environment that is conducive for the growth of mucormycetes such as Mucor and Rhizopus, leading to fungal infections.
Diabetic ketoacidosis creates an acidic environment in the body which facilitates the growth of Mucor and Rhizopus species. These organisms thrive in high glucose and acidotic conditions, making individuals with diabetic ketoacidosis particularly susceptible to infections like rhinocerebral mucormycosis.
Mucor spp. and Rhizopus spp. exhibit characteristic wide-angle, non-septate or minimally septate branching hyphae when observed under a microscope.
The antifungal drug amphotericin B is commonly used to treat mucormycosis. It is often used in combination with surgical debridement (removal of necrotic or infected tissues), in order to control the spread of the infection. Additionally, controlling the underlying conditions that increase susceptibility, such as immunosuppression or diabetic ketoacidosis, is a vital part of treatment.
