Transcript Diseases
Diseases Chapters 21-26 Microorganisms and human Disease • Things to cover – Diseases of Skin and Eyes – Diseases of the Nervous system – Diseases of the Cardiovascular & Lymphatic System – Diseases of the Respiratory System – Diseases of the Digestive System How I will tackle these • Structure and function. • Normal Microbiota • Some of the diseases (More diseases to come) – Bacterial – Viral – Other • You will provide more of the details Skin and Eyes Ch 21 • Physical and chemical barrier against microbes • Moist areas have greater number of bacteria • Epidermis contains flattened cells of keratin and is essentially waterproof. • Dermis is the living part, contains follicles, ducts and glands that act as week point for bacterial invasion. • Sebum and perspiration can inhibit growth of microbes. • Same also provide nutrients to microbiota • The body and body cavities are lined with epithelia cells. • Mucous membranes secrete mucus. What does the integument system do? Microbiota • Divide rapidly, resistant to desiccation and high salt. • Mostly gram positive cocci. • Never completely absent. • Propionibacterium metabolize oil • Pityrosporum ovale are yeast that grow in oily secretions, cause dandruff. Staphylococcal Skin Infections • Folliculitis – Infections of hair follicles • Sty – Folliculitis of an eyelash • Furuncle – Abscess; pus surrounded by inflamed tissue • Carbuncle – Inflammation of tissue under the skin Staphylococcal Skin Infections • Impetigo of the newborn • Toxemia • Scalded skin syndrome • Toxic shock syndrome Figure 21.4 Streptococcal Skin Infections • Streptococcu s pyogenes • Group A betahemolytic streptococci • M proteins Figure 21.5 • Erysipelas Streptococcal Skin Infections • Impetigo Figure 21.6, 7 Invasive Group A Streptococcal Infections • Streptokinases • Hyaluronidase • Exotoxin A, superantigen • Cellulitis • Necrotizing fasciitis Figure 21.8 Infections by Pseudomonads • Pseudomonas aeruginosa – Gram-negative, aerobic rod – Pyocyanin produces a blue-green pus • Pseudomonas dermatitis • Otitis externa • Post-burn infections Warts • Papillomaviruses – Treatment: • Removal – Imiquimod (stimulate interferon production) – Interferon Poxviruses • Smallpox (Variola) – Smallpox virus (Orthopox virus) – Variola major has 20% mortality – Variola minor has <1% mortality • Monkeypox – Prevention by smallpox vaccination Figure 21.9 Measles (Rubeola) • Measles virus • Transmitted by respiratory route • Macular rash and Koplik's spots • Prevented by vaccination • Encephalitis in 1 in 1000 cases • Subacute sclerosing panencephalitis in 1 in 1,000,000 cases Figure 21.14 Cutaneous Mycoses • Dermatomycoses: tineas or ringworm • Metabolize keratin • Trichophyton infects hair, skin, nails • Epidermophyton infects skin and nails • Microsporum infects hair and skin • Treatment – Oral griseofulvin – Topical miconazole Cutaneous Mycoses Figure 21.16 Candidiasis • Candida albicans (yeast) • Candidiasis may result from suppression of competing bacteria by antibiotics • Occurs in skin; mucous membranes of genitourinary tract and mouth • Thrush is an infection of mucous membranes of mouth • Topical treatment with miconazole or nystatin Candidiasis Figure 21.17 Pediculosis • Pediculus humanus capitis (head louse) • P. h. corporis (body louse) – Feed on blood – Lay eggs (nits) on hair – Treatment with topical insecticides Figure 21.19 Microbial Diseases of the Eye • Conjunctivitis (pinkeye) – Haemophilus influenzae – Various microbes – Associated with unsanitary contact lenses • Neonatal gonorrheal ophthalmia – Neisseria gonorrhoeae – Transmitted to newborn's eyes during passage through the birth canal – Prevented by treatment newborn's eyes with antibiotics Nervous System Ch22 • CNS is brain and spinal cord. Is encased and protected by bone and membranes. • PNS are nerves outside of the Central nervous system. Is not protected as extensively and is a rout into the CNS. • Membranes of the CNS – Dura mater, arachnoid and piamater More nervous • Cerebrospinal fluid instead of blood circulates between the arachnoid and piamater in the subarachnoid space. • Cerebrospinal fluid is totally separate from the blood and circulatory system. • Blood brain barrier • Entry to CNS by bacteria is through peripheral nerves, though blood and lymphatic system. • Meningitis is an infection of the meninges • Encephalitis is an infection of the brain. What does the Nervous system do? Normal Microbiota? Bacterial Meningitis • • • • • Fever, headache, stiff neck Followed by nausea and vomiting May progress to convulsions and coma Diagnosis by Gram stain of CSF Treated with cephalosporins Bacterial Meningitis Table 22.1 Tetanus • Clostridium tetani • Gram-positive, endospore-forming, obligate anaerobe • Grows in deep wounds • Tetanospasmin released from dead cells blocks relaxation pathway in muscles • Prevention by vaccination with tetanus toxoid (DTP) and booster (dT) • Treatment with tetanus immune globulin Botulism • Clostridium botulinum • Gram-positive, endospore-forming, obligate anaerobe • Intoxication due to ingesting botulinal toxin • Botulinal toxin blocks release of neurotransmitter causing flaccid paralysis • Prevention: – Proper canning – Nitrites prevent endospore germination in sausages Botulism • Treatment: supportive care and antitoxin • Infant botulism results from C. botulinum growing in intestines • Wound botulism results from growth of C. botulinum in wounds. Transmissible Spongiform Encephalopathies • Caused by prions – Sheep scrapie – Creutzfeldt-Jakob disease – Kuru – Bovine spongiform encephalopathy • Transmitted by ingestion or transplant or inherited • Chronic, fatal Transmissible Spongiform Encephalopathies Figure 22.17a Cardiovascular and Lymphatic Systems Ch 23 • Consists of heart, blood and blood vessels • Lymph, lymph vessels, lymph nodes and lymphoid organs. Body Fluids and Flow • Heart circulates substances to and from tissue cells. • Blood is a mixture of plasma and cells. • Most substances are dissolved in plasma • RBC’s carry oxygen. • WBC’s are involved in defense. • Interstitial fluid is essentially plasma and exits from capillaries Normal Microbiota? • Life Loads? Sepsis and Septic Shock • Sepsis – Bacteria growing in the blood • Severe sepsis – Decrease in blood pressure • Septic shock – Low blood pressure cannot be controlled Figure 23.3 Sepsis • Gram-negative Sepsis – Endotoxins caused blood pressure decrease – Antibiotics can worsen condition by killing bacteria • Gram-Positive Sepsis – Nosocomial infections • • • • Staphylococcus aureus Streptococcus pyogenes Group B streptococcus Enterococcus faecium and E. faecalis Viral Hemorrhagic Fevers Classic Yellow fever Flavivirus Aedes aegypti Monkeys Dengue & DHF Flavivirus • • A. aegypti A. albopictus Marbug Filovirus • Monkeys (?) Ebola Filovirus • Monkeys (?) Lassa fever Arenavirus • Rodents Argentine hemorrhagic fever Arenavirus • Rodents Bolivian Arenavirus • Rodents Emerging No known reservoir Malaria • Plasmodium vivax, P. ovale, P malariae, P. falciparum • Anopheles mosquito 12.31b Respiratory System Ch 24 • Most common type of infection • Usually first on way to infection. Microbial Diseases of the Upper Respiratory System • Laryngitis: S. pneumoniae, S. pyogenes, viruses • Tonsillitis: S. pneumoniae, S. pyogenes, viruses • Sinusitis: Bacteria • Epiglottitis: H. influenzae • Upper respiratory: nose, pharynx, middle ear and auditory tubes. • Filtration by coarse hairs • Ciliated mucous membranes of nose and throat trap airborne particles (greater than 10um) • Associated with lymphoid tissues (tonsils, and adenoids) Lower respiratory system • Larynx, trachea, bronchial tubes and alveoli. • Ciliary escalator prevents microbes from reaching the lungs. • Alveolar macrophage protect lungs. • Respiratory mucus contains IgA antibodies Microbial Diseases of the Lower Respiratory System • Bacteria, viruses, & fungi cause: – Bronchitis – Bronchiolitis – Pneumonia What do the lungs do? Normal Microbiota • Of throat and nasal cavity can include pathogens. • Lower respiratory system is usually sterile because of ciliary escalator. Opportunistic fungi involved in respiratory disease: • Aspergillus • Rhizopus • Mucor Mucor rouxii Figure 12.2b, 12.4 Digestive System Ch 25 • Second most common illnesses • Usually ingestion of microbes and toxins. • Fecal-oral transmission is broken by proper disposal of sewage, disinfection of drinking water and proper food prep and storage. Structure Function • GI or alimentary canal: mouth, pharynx, esophagus, stomach, small intestine and large intesting, colon, anus. • Accessory organs: teeth, tongue, salivary glands, liver, gallbladder and pancrease. • Charged with ingestion, digestion, absorption and elimination. Normal microbiota • Lots and unknown number occupy the mouth. • Streptococcus mutans in mouth produces acid. • Dextran from bacteria is plaque • Bacteria number are reduced in stomach. • Normal flora in lower gut. Normal Microbiota • >300 species in mouth • Large numbers in large intestine, including: – Bacteroides – E. coli – Enterobacter – Klebsiella – Lactobacillus – Proteus What does the gut do? Bacterial Diseases of the Lower Digestive System • Symptoms usually include diarrhea, gastroenteritis, dysentery • Treated with fluid and electrolyte replacement • Infection caused by growth of pathogen – Incubation from 12 hr to 2 wk • Intoxication caused by ingestion of toxin – Symptoms appear 1-48 hr after ingestion Urinary and Reproductive systems • Regulates chemical components of blood excretes nitrogenous waste. • Infections can be from outside source or form normal microfloura. • Microbes can use a system to transfer gametes to also transfer themselves. Microbial Diseases of the Urinary and Reproductive Systems • Microbes usually enter the urinary system through the urethra • Microbes usually enter the reproductive system through the: – Vagina (females) or urethra (males) Function? Normal Microbiota • Urinary bladder and upper urinary tract sterile • Lactobacilli predominant in the vagina • >1,000 bacteria/ml or 100 coliforms/ml of urine indicates infection Sexually Transmitted Diseases (STDs ) • Prevented by condoms • Treated with antibiotics Websites. • STD’s http://hab.hrsa.gov/publications/hrsawome n/colorplates/colorplates.htm