Neutropenia in the context of "Mucormycosis"

A superinfection is a second infection superimposed on an earlier one, especially by a different microbial agent of exogenous or endogenous origin, that is resistant to the treatment being used against the first infection. Examples of this in bacteriology are the overgrowth of endogenous Clostridioides difficile that occurs following treatment with a broad-spectrum antibiotic, and pneumonia or sepsis from Pseudomonas aeruginosa in some immunocompromised patients.

In virology, the definition is slightly different. Superinfection is the process by which a cell that has previously been infected by one virus gets co-infected with a different strain of the virus, or another virus, at a later point in time. In some cases viral superinfections may be resistant to the antiviral drug or drugs that were being used to treat the original infection. Viral superinfections may also be less susceptible to the host's immune response. In Zika virus infection, there is some evidence that primary infection of another Flavivirus, Binjari virus, results in the direct inhibition of a secondary infection of Zika virus in mosquito cells. Recent metagenomic analyses have demonstrated that the novel coronavirus, SARS-CoV-2 can be associated with superinfection and colonization of other pathogens, such as rhinovirus species and Moraxella spp.

A granulocyte transfusion is a medical procedure in which granulocytes are infused into a person's blood. Granulocytes are a category of white blood cell that includes neutrophils, eosinophils, and basophils. Granulocyte transfusions were historically used to prevent and treat infections in people with neutropenia (an abnormally low level of neutrophils), but the practice declined in popularity in the 1980s. Interest in the procedure increased in the 1990s due to the development of more effective methods for harvesting granulocytes and a growing population of people with severe neutropenia from chemotherapy. However, the treatment's efficacy remains poorly understood and its use is controversial.

Granulocytes are most often collected through leukapheresis, a process that separates the donor's white blood cells from their red blood cells and plasma. Donors may be given corticosteroids or granulocyte colony-stimulating factor to increase their granulocyte count prior to the blood collection. Granulocytes have a short shelf life and it is recommended that they are transfused within hours of collection. Adverse effects from granulocyte transfusions include fever, chills, respiratory symptoms, transfusion-transmitted infections, and the development of antibodies against human leukocyte antigens, which can interfere with subsequent transfusions.