Plate 50 Toxins

Toxins: poisonous substances produced by organisms (microorganisms, in our case)

Exotoxins Exotoxins: produced within cytoplasm of bacteria and released into the surrounding environment – Exo = “out” – Produced by Gram-positive bacteria – Toxins are soluble in body fluids

Exotoxins Released after bacteria cell is inside the body or in food (and consumed by host) Spread through body by blood and damage organs Effects of exotoxins: – Damage cell membranes of tissue – Interrupt metabolic function – Interfere with cellular functions

Exotoxins – Enterotoxin Staphylococcus aureus produce enterotoxins that are absorbed by the cells that line the intestines Entero = “intestine” Symptoms: – Nausea – Vomiting – Abdominal cramps – Diarrhea Ex: S. aureus can result in Toxic Shock Syndrome, commonly found in menstruating women who use tampons

Staphylococcus aureus – “golden cluster seed”

Staph Infection Skin infections: – Pimples – Folliculitis – Impetigo

Exotoxins – Neurotoxin Clostridium botulinum produce neurotoxins that affect the nervous system Neuro = “nerve” Prevents the release of acetylcholine (a neurotransmitter) at neuromuscular junctions Results in paralysis, since nerve impulses cannot pass to muscles

Botulism

Exotoxins – Neurotoxin Clostridium tetani produce a neurotoxin that affects nerve cells responsible for skeletal muscle contractions Muscles remain constantly contracted and rigid

Tetanus “Lock-jaw” – muscle contraction in the face and neck

Tetanus

Exotoxins – Cytotoxin Corynebacterium diphtheriae kill respiratory cells by interfering with protein synthesis Dead respiratory cells and debris collect in mucus, block small air passageways, and make breathing difficult Cyto = “cell”

Diptheria Note the large whitish swelling in the throat

Endotoxins Endotoxins: made of components of bacterial cell wall – Endo = “in” – Produced by Gram-negative bacteria – Made of lipopolysaccharides (LPS) – Released when the bacteria cell wall is broken down (through phagocytosis or antibiotics)

Endotoxins Unlike some exotoxins, endotoxins are not tissue specific – they affect a wide range of tissues (systemic) Symptoms: – Dilate blood vessels (lower blood pressure) – Tissue failure due to lack of nutrition and oxygen – Fever – Muscular weakness – Low levels of white blood cells – Hemorrhaging of blood vessels