Question: Why can't some fungi's be cured with antibiotics?

Robert Hampson answered on 20 Nov 2014:

It was actually fungi which formed many of our first antibiotic! Penicillin was isolated from the penicillium fungus. Understandably, it is immune to its own poison!

Fungi and Bacteria are biologically quite different to each other. The targets which antibiotics hit are present and important in bacterial cells but they are either not present or not important in fungal cells.

Bacteria are, in fact, very different to human cells, they are called prokaryotic, they have no nucleus. Fungi, however, are called eukaryotic (the same as human cells), they do have a nucleus and they are generally much more similar to human cells. Because the fungal cells are much more similar they are also much more difficult to treat as many drugs which kill fungi will also kill human cells. There are fewer targets which are present and important to fungi which are also either not present or not important in human cells.