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Disease of Skin and Eyes Ch 21. Necrotizing fasciitis. Streptococcus pyogenes Causes extensive tissue damage Treatment is Surgical removal of tissue, Penicillin. Invasive Group A Beta Hemolytic Streptococcal Infections. Streptokinases Hyaluronidase Exotoxin A, superantigen Cellulitis
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Necrotizing fasciitis • Streptococcus pyogenes • Causes extensive tissue damage • Treatment is Surgical removal of tissue, Penicillin
Invasive Group A Beta Hemolytic Streptococcal Infections • Streptokinases • Hyaluronidase • Exotoxin A, superantigen • Cellulitis • Necrotizing fasciitis Figure 21.8
Impetigo • Staphylococcus aureus or Streptococcus pyogenes • Superficial skin infection; isolated pustules • Penicillin for Streptococcus infections • Methicillin or cephalosporin for Staphylococcus
Streptococcal Skin Infections • Erysipelas • Impetigo Figure 21.6, 7
Shingles • Varicella-zoster virus (VZV) • Vesicles similar to chickenpox; typically on one side of waist, face and scalp, or upper chest • Usualy along dermatome’s. One or 2 • Can cause persistant pain in the affected nerves postherpetic neuralgia • Normal immunity is best • Acyclovir esp for immunocompromised
Boils • Staphylococcal infection • A somewhat larger pus-containing lesions within the dermis. • May cause abscesses that are accumulations of pus that may penetrate into deeper tissues and develop into cellulitis • Can be treated with penicillins • May need to be lanced and foreign body removed.
Acne • Small inflamed papules and pustules • Heal spontaneously within a few days. • When Propionibacterium acnes (anaerobic) produces fatty acids and causes an immune response. • Skin peels reduce the chance of pores bercomming clogged • Tetracyclines can reduce the amount of bacteria
Chicken Pox • Mild disease in children • VZV herpes only in humans. • Oka live attenuated vaccine • With Aspirin can cause Reye’s syndrome • Develop into shingles as an adult • 100 deaths a year
Herpes • Herpes simplex virus type 1 • Large Double stranded DNA virus • Develops latent infection in nerves • Most commonly as cold sores-vesicles around mouth; can also affect other areas of skin and mucous membranes • Fluid in vessels contains virus and is infectious • Acyclovir may modify (reduce)symptoms.
Rubella (German measles) • Rubella virus • Mild disease with a rash resembling measles, but less extensive and disappears in 3 days or less • No treatment. • MMR • Can cause Birth defects and death to undeveloped fetus • May want to screen women of childbearing age for antibodies
Measles (Rubeola) • Measles virus • Transmitted by respiratory route • Macular rash and Koplik's spots • Prevented by vaccination(MMR) at 15mo • Encephalitis in 1 in 1000 cases • Subacute sclerosing panencephalitis in 1 in 1,000,000 cases Figure 21.14
Ringworm • Dermatophytes • Infect the bodies outermost surface • Depends on the bodys immune response • Red, weeping, swelling • Topical antifungals • Miconazole • clotrimazole
Scabies • Sarcoptes scabiei a mite • Transferred from person to person or by fomites • Common worldwide • Lives on skin, female burrows into the skin to lay eggs. • Resembles other itchy skin disease, need to look for mites or eggs. • Lasts a long time (7 year itch) • Arachnicide gamma benzene
Meningitis • Neisseria meningitidis • Transferred by respiratory droplets • May live in nose and throat as normal flora • Vaccine does not cover all serotypes • Rapid onset, high fever, stiff nect, headache worsteing, possible agitated behavior similar to drug overdose • Rifampin and Penicillin G
Tetanus • Clostridium tetani • Normal flora of animals some humans. • Neurotoxin made in bacteria in a wound. • Immunization • Stiff muscles
Botulism • Clostridium botulinum • Affects the preipheral nervous system. • Stops release of acetylcholene, resulting in flaccid paralysis • Support of systems untill toxin is neutralized. • Antiserum • Honey a risk in infant botulism
Poliomyelitis • Enterovirus group: polioviruses • Paralysis only in 1% of infected individuals • Multiplies in throat and intestines. • Viremia results in infection of the motor cells of CNS. Killing these cells. • The Sabin oral vaccine is no longer used in the US because of reversions. • Inactivated now used.
Rabies • Family Rhabdoviridae genus Lyssavirus bullet shaped negative-sense RNA • Initially nonspecific compatible with Fluelike illness. (fever, headache and general malaise 10 days to 6 years after infection. • Hydrophobia • Not treatable after symptoms occur death in 100%
Rabies 2 • Treatment: post exposure prophylaxis • Antirabies vaccine and immune globulin injections. • Skunk is the primary reservoir in the bay area.
Trypanosomiasis African Sleeping sickness • Trypanosoma brucie gambiense • Spread by tsetse fly vector • Early symptoms include reduction of physical and mental activity, will move into coma as organism enters CSF. • Treatment,eflornithine (enzyme blocker) • Vaccine is being developed, hampered by antigen variability mainly avoidance.
Crutzfeldt-jakob disease • Spongiform encephalophathies • 200 cases per year in the us, often in families. • Prion-contaminated tissue • Not known. • May be infected blood or tissue
Transmissible Spongiform Encephalopathies Figure 22.17a
Rheumatic fever • Group a beta hemolytic streptococci (Streptococcus pyogenes) • Autoimmune condition; repeated streptococcal infections result in antibodies that damage the heart valve tissue. • Reason that strep throat is vigorously treated. • Still sensitive to Penicillin.
Yellow Fever • Fiver chills and headache followed by nausea and vomiting. Followed by jaundice. • Mortality rate 20% • Viral hemorrhagic fever carried by mosquito • Monkey are a reservoir but human-human is mostly how it happens. • Live attenuated viral vaccine
Anthrax • Symptoms vary according to portal of entry • Cutaneous • Gastrointestinal • Inhallational (pulmonary) most deadly • Mild fever, coughing and some chest pain. • Mild symptoms not usually responded to • Progresses to septic shock in 2-3 days • Antibiotics if administered on time.
Malaria • Plasmodium • A mosquito-borne disease common to hot climates, characterized by fever and chills at intervals may be fatal in small children. • Working on vaccine.
Elephantitis • Student talk
Schistosomiasis • Schistosoma spp • Eggs produced by schistosomes lodge in tissue and induce damaging inflammation.
Strep throat • Streptococcus pyogenes • Inflame Mucous membranes of the throat
Legionellosis • Legionella pneumophila • Potentially fatal pneumonia that tends to affect older males who drink or smoke heavily. Pathogen grows in water such as air-conditioning towers and shower heads.
Influenza • Influenzavirus many types • Characterized by chills, fever, headache, and muscular aches. Virus changes antigenic character rapidly, so there is limited immunity following recovery. • 10-20k Americans die a year. • Transferred from humans to animals • Usually from the orient.
Histoplasmosis • Histoplasma capsulatum • Fungal pathogen grows in soil, esp if contaminated with bird droppings. Widespread in Ohio and Mississippi river valleys; occasionally fatal.
Colds • Rhinoviruses, Coronaviruses • Young average 4 per year. • Isolate populations develop group immunity. • Sneezing excessive nasal secretion. • Usually not accompanied by fever • Last about a week. OCD’s do not reduce this
Food poisoning • Staphylococcus aureus Exotoxins • Toxin causes rapid onset of nausea, vomiting and diarrhea