Fungi and Human Mycoses
Fungi are eukaryotic cells, with membrane bound organelles, a nucleus, and 18s RNA sequences.
Their cell membrane contains ergosterol where ours has cholesterol.
Their cell wall contains complex polysaccharides that stain
Both ergosterol and cholesterol synthesis go from squalene to lanosterol to zymosterol, which is
their final common precursor.
This has a special hydrophobic polyene unit that binds ergosterol in the membrane. For
Deep Pathogenic Fungi Histoplasmosis
Pathogenic fungi can occassionally cause infection in normal hosts. These fungi include
Histoplasmosis, Coccidioides, and Blastomyces.
They are encountered in their natural environments, not person to person.
Common Cutaneous and Mucosal Mycoses
Fungus is confined to the dead skin and doesnt illicit inflammation. Cosmetic problem only.
Tinea versicolor is a discoloration of the skin caused by the fungus Malassezia furfur. Under th
Different opportunistic mycoses occur depending on the type of opportunity:
Altered T-cell function (AIDS) Mucocutaneous candida, Cryptococcosis, Pneumocystis, Histo
Altered phagocytic function (neutropenia) Candidiasis, As
Introduction to Parasites
Parasite = organism that lives in another and draws nourishment from the host, usually to the
hosts detriment. This often applies to protozoa, worms, and arthropods.
Protozoa are small, single-cell organisms including f
Parasitic Nematode Infections
Most helminths do not multiply inside the definitive host. The major exception is Strongyloides.
Distribution in the human population follows a negative binomial pattern.
Most helminth infections evoke eosinophilia,
Tissue Helminths and Travel Medicine
Schistosomiasis / Bilharzia
Caused by Schistosoma heamatobium or Schistosoma mansoni. Exposure to fresh water
with larval cercariae is the mode of infection. Snails are an intermediate host.
The cercariae pe
Theory of Bacterial Antibiotic Resistance
Intrinsic resistance is built-in species-specific resistance. It is chromosomal and predictable.
Acquired resistance is not predictable, and occurs through four processes:
-mutation, which alters target
Selective toxicity with anti-parasitic drugs:
-parasite location (for example, lumenal drugs arent even absorbed by the gut)
-differences in host and parasite metabolic pathways
-differences in isoform enzymes
Blood and Tissue Protozoans
Humans are the only reservoir for the four Plasmodium species (falciparum, vivax, ovale, and
malariae). These are all transmitted by the Anopheles mosquito.
Mosquito bite transmits sporozoites, a few of which