Microbio - Exam 4 review

Biology 225
Study Outline Exam 4 Chapter 21: Microbial Diseases of the Skin & Eyes
Structure & Function of Skin: - epidermis: thin outer layer of skin, composed of epithelial cell layers o keratinocytes in outermost layer (stratum corneum) contain a waterproofing protein called keratin o unbroken epidermis is effective barrier against microbes dermis: inner thick layer of skin, composed mainly of connective tissue o hair follicles, sweat glands ducts & oil gland ducts provide portals of entry for microorganisms perspiration from sweat glands provides moisture & nutrients for microbial growth, but salt inhibits growth sebum from oil glands provides lipids & proteins, but low pH from fatty acids inhibits microbial growth mucous membranes: epithelium lining GI, respiratory, urinary & genital tracts o contains epithelial cells that secrete mucus that traps particles & microbes o acidic pH limits microbial populations

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Normal Microbiota of Skin: - on superficial surfaces, some aerobic bacteria produce fatty acids from sebum that limits growth of other microbes - some gram-positive bacteria (staphylococci & micrococci) are able to grow in the high salt concentrations of skin o Staphylococcus epidermidis & other coagulase negative staphylococci o Staphylococcus aureus (especially in abnormal skin (eczema)) o washing can reduce their numbers but will not eliminate them o areas with more moisture have higher populations (metabolize secretions from sweat glands (odor)) - gram-positive pleomorphic rods (diphtheroids) o Propionibacterium acnes are typically anaerobic & inhabit hair follicles  growth is supported by breakdown of sebum to form propionic acid, which keeps skin pH between 3 & 5 o Corynebacterium xerosis are aerobic rods that occupy the skin surface - yeast Pityosporum ovale grows on oily skin secretions (may cause dandruff) o dandruff shampoos contain the antifungal ketoconazole, or zinc pyrithione or selenium sulfide that target yeast

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Bacterial Diseases of the Skin
Staphylococcus aureus: - coagulase-positive (clots) & may produce leukocidins, exfoliative toxin & enterotoxins - folliculitis: infections of the hair follicles o also sties (styes, infected hairlash follicles)), boils (furuncles, inflammation present) & carbuncles (progressed boils that cause deep inflammation under skin) o cause: Staphylococcus aureus - impetigo (of the newborn): thin-walled vesicles on the skin that rupture & crust over o cause: Staphylococcus aureus - scalded skin syndrome: caused by staphylococcal toxins (often from bacteriophages) o bright red lesions around nose & mouth spread; skin of affected areas peels off o most frequently observed in newborns from staph infections - toxic shock syndrome: caused by staphylococcal toxin (TSST-1) o fever, vomiting & rash are followed by shock Streptococcus: - cause of many diseases, including meningitis, pneumonia, sore (strep) throats, otitis media, endocarditis, Rheumatic fever - impetigo: local infection, fluid-filled vesicles on the skin that rupture & crust over o cause: Streptococcus pyogenes o route of transmission: direct contact, through abrasions or insect bites - erysipelas: reddish patches on skin often following strep throat - if streptococcal skin infections reach deeper tissues, rapid & severe destruction of tissue cells, muscle & fascia may occur (cellulitis, myositis & necrotizing fasciitis) o treatment includes surgical removal of infected/damaged tissue & penicillin Pseudomonad infections: - pseudomonads cause pseudomonad dermatitis (rash often associated with common swimming pools/saunas) & otitis externa (swimmer’s ear) - pseudomonads can cause opportunistic infections in the immunocompromised and burn patients - Pseudomonas aeruginosa can easily develop resistance and can grow easily in standing water & some disinfectants; troublesome in hospital settings - treatment: fluoroquinolones & antipseudomonal ß-lactam antibiotics Acne: - cystic acne: unusually severe acne forming cysts & subsequent pitted scarring - often results from blockage of sebum channels to skin surface, & subsequent breakdown of sebum to form free fatty acids that cause an inflammatory response - cause: Propionibacterium acnes - treatment: benzoyl peroxide, benzamycin (benzoyl peroxide with erythromycin), tretinoin (Retin-A®) (inactivates benzoyl peroxide, shouldn’t be combined), & isotretinoin (Accutane®) (teratogen, causes fetal damage in pregnant women)

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Viral Diseases of the Skin
Warts: raised/papular projection of skin from cell proliferation - cause: papillomaviruses (HPV) - route of transmission: direct contact - treatment: cryotherapy (cold liquid nitrogen), electrodessication (drying with electrical current), burning with acids & prescription drugs (podophyllum; podofilox) Smallpox: viral infection leads to pustular lesions on skin & mucous membranes - cause: poxvirus (smallpox (variola) virus) - route of transmission: respiratory route; can infect many internal organs & move into bloodstream & skin - smallpox has been eradicated from the human population due to an effective vaccine Chickenpox: viral infection leads to fluid-filled vesicles & rash; vesicular rash usually appears on face, neck & back (also chest & shoulders) - cause: herpesvirus varicella-zoster (human herpesvirus-3) - route of transmission: respiratory route - complication: occasionally Reye’s syndrome (especially in young) – nausea, vomiting & signs of brain dysfunction; coma & death can result - treatment/prevention: acyclovir, varicella-zoster vaccine Shingles: new viral infection leads to vesicles & rash along cutaneous sensory nerves of skin (localized to waist area; also face, chest & back) - more common in adults; reactivation of latent varicella-zoster virus (from chickenpox) - cause: herpes zoster virus - route of transmission: latent infection reactivated - treatment/prevention: acyclovir, varicella-zoster vaccine Herpes Simplex: infections frequently subclinical, but many cases develop lesions (cold sores, fever blisters) - cause: human herpesvirus herpes simplex virus (HSV-1 & HSV-2) - route of transmission: HSV-1 by skin contact, HSV-2 by sexual contact - complications: can remain latent in ganglia of trigeminal nerve (HSV-1) or sacral nerve (HSV-2); events such as UV exposure & hormonal changes can signal recurrence; occasionally herpes encephalitis - treatment/prevention: acyclovir; antiviral medications Measles (Rubeola): viral infection leads to raised or papular skin lesions; macular rash spreads from face to trunk & extremities - cause: measles virus (paramyxovirus) - route of transmission: respiratory route - lesions on the oral mucosa (opposite molars) called Koplik’s spots (red patches with central white spots) are a diagnostic indicator of measles - complications: middle ear infections, pneumonia, encephalitis - treatment/prevention: vaccination (measles vaccine, MMR)
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Rubella (German measles): viral infection leads to rash of red small spots (not raised) & light fever - cause: rubella virus (togavirus) - route of transmission: respiratory route - complications: can cause fetal damage (deafness, cataracts, mental retardation, death) if contracted during pregnancy (congenital rubella syndrome) - treatment/prevention: vaccination (rubella vaccine, MMR)

Fungal Diseases of the Skin and Nails
Cutaneous Mycoses - fungi that colonize the outer layer of the epidermis cause dermatomycoses - Microsporum, Trychophyton, and Epidermophyton cause dermatomycoses called ringworm, or tinea - grow on keratin-containing epidermis (hair, skin, nails) - ringworm and athlete's foot are usually treated with topical antifungal chemicals. Subcutaneous Mycoses - sporotrichosis results from a soil fungus that penetrates the skin through a wound - produce subcutaneous nodules along the lymphatic vessels. Candidiasis - Candida albicans causes infections of mucous membranes and is a common cause of thrush (in oral mucosa) and vaginitis - C. albicans is an opportunistic pathogen that may proliferate when the normal bacterial microbiota are suppressed - treatment: topical antifungals

Parasitic Infestation of the Skin
scabies is cause by a mite burrowing and laying eggs in the skin pediculosis is an infestation by Pediculus humanus (louse)

Bacterial Diseases of the Eye:
Neonatal Gonorrheal ophthalmia: - cause: Neisseria gonorrhoeae - route of transmission: infected in birth canal - treatment: silver nitrate, tetracycline & erythromycin Inclusion conjunctivitis: - cause: Chlamydia trachomatis - route of transmission: infected in birth canal; possibly unchlorinated swimming pools - treatment: tetracycline ointment (also for trachoma) Trachoma: - cause: Chlamydia trachomatis - route of transmission: hand contact, fomites (towels) & flies - causes blindness (due to conjunctivitis & scarring of the cornea)
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Chapter 22: Microbial Diseases of the Nervous System
Structure & Function of the Nervous System: - central nervous system (CNS): brain & spinal cord o brain: protected by skull bones o spinal cord: protected by vertebral column o covered by 3 layers of membranes called meninges (dura mater, arachnoid & pia mater from outside in) o cerebrospinal fluid (CSF) circulates in subarachnoid space o blood-brain barrier prevents many substances, including toxins & antibiotics, from entering brain  only lipid-soluble molecules can normally pass  inflammation of brain allows more substances to pass - peripheral nervous system (PNS): nerves that branch from the CNS - microorganisms can enter CNS through trauma, along peripheral nerves & through blood & lymphatics - meningitis: infection of the meninges; can be caused by viruses, bacteria, fungi & protozoa - encephalitis: infection of brain

Bacterial Diseases of the Nervous System
Bacterial Meningitis: - symptoms: initially fever, headache, stiff neck, followed by nausea & vomiting (may progress to convulsions & coma) - 3 major causes: Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis o over 50 bacterial species can cause meningitis o Haemophilus influenzae meningitis  H. influenzae is part of the normal throat flora; requires blood factors for growth  H. influenzae type B (Hib) is most common cause of meningitis in children under 4 years old  prevention: conjugated vaccine (Hib vaccine) against capsular polysaccharide antigen (vaccination series begins at about 2 months) o Neisseria meningitis (meningococcal meningitis)  N. meningitidis also found in normal throat & nose  symptoms due to endotoxin; throat infection followed by bacteremia (septicemia in some) & meningitis; may access meninges through blood  most often occurs in young children (under 2 years)  prevention: capsular polysaccharide vaccine (not effective in young children; used routinely in US military) o Streptococcus pneumoniae meningitis (pneumococcal meningitis)  S. pneumoniae found commonly in nasopharynx  rare, but has high mortality rate; children & hospital patients at greatest risk  vaccine for pneumococcal pneumonia may offer some resistance  conjugated vaccine has been introduced
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Diagnosis & Treatment of Bacterial Meningitis: o broad-spectrum cephalosporins are first choice, even before identification of pathogen o diagnosis requires sample of CSF from spinal cord (spinal tap)  based on Gram stain & serological tests of bacteria in CSF, & cultures on blood agar Listeriosis: meningitis in newborns, immunosuppressed, pregnant women & cancer patients o cause: Listeria monocytogenes o acquired by ingestion of contaminated foods o may be asymptomatic in healthy adults o can grow within phagocytes o L. monocytogenes can cross placenta & cause spontaneous abortion & stillbirth

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Tetanus: - cause: Clostridium tetani - C. tetani is anaerobe found in soil; enters wound (caused by dirty needles, blades, rusty nails) & causes localized infection - C. tetani produces neurotoxin tetanospasmin that causes spasms, contractions of jaw muscles (lockjaw), & death by spasms of respiratory muscles - prevention: DTaP (diphtheria, tetanus & acellular pertussis) vaccine - following injury, immunized person can receive booster of tetanus toxoid; unimmunized person can receive tetanus immune globulin - debridement (removal of tissue) & antibiotics may be used to control infection Botulism: - cause: Clostridium botulinum - produces exotoxin (neurotoxin) that inhibits transmission of nerve impulses - symptoms: blurred vision & progressive flaccid paralysis; possibly death from respiratory & cardiac failure - endospores killed by proper canning of foods - toxin heat-labile; destroyed by boiling Leprosy: - cause: Mycobacterium leprae - diagnosis: acid-fast stain & lepromin test (injection of lepromatous tissue extract) - not very contagious; spread by prolonged contact with exudates from wounds - untreated individuals may die from secondary infections (TB) rather than leprosy - treatment: sulfone drugs, rifampin 4-5 days & outpatient treatment

Viral Diseases of the Nervous System
Poliomyelitis: - cause: poliovirus - transmitted mainly through ingested water - about 1% of cases result in paralysis
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Salk vaccine: virus inactivated with formalin (IPV) o booster shots needed every few years Sabin vaccine (oral polio vaccine): 3 living attenuated strains of the virus o more popular in US; uses orange-flavored drink rather than shots o attenuated virus may cause disease in secondary contacts (1:750,000) o for this reason, IPV is now recommended vaccine

Rabies: - cause: rabies virus (rhabdovirus) - usually transmitted by animal bites or saliva - symptoms: virus travels along peripheral nerves to CNS & causes encephalitis; spasms of mouth & pharynx when swallowing (sight of water may trigger spasms: hydrophobia); excessive salivation; possible death from respiratory failure - diagnosis: immunofluorescence of virus in saliva, serum or CSF - treatment: postexposure prophylaxis: series of antirabies vaccine & immune globulin injections o human diploid cell vaccine (HDCV) or chick-embryo vaccine administered in a series of 5-6 injections over 28 days, with human rabies immune globulin (RIG) Arboviral encephalitis: - cause: mosquito-borne viruses (arbovirus or arthropod-borne virus) - incidence increases during summer (mosquito proliferation) - horses & humans affected - viruses: Western equine encephalitis, Eastern equine encephalitis, St. Louis encephalitis, California encephalitis, Japanese B encephalitis - West Nile virus infected many animals & some humans in NYC in 1999 - incidence can be estimated by serological tests on animals

Fungal Disease of the Nervous System
Cryptococcus neoformans meningitis (Cryptococcosis) - cause: Cryptococcus neoformans - mode of transmission: inhalation of dried infected pigeon droppings (from soil) - symptoms: lung infection – frequently subclinical; can spread to bran & meninges & cause chronic meningitis, especially in immunosuppressed - treatment: amphotericin B & flucytosine

Protozoan Diseases of the Nervous System
African Trypanosomiasis (sleeping sickness) - cause: Trypanosoma brucei gambiense, Trypanosoma rhodesiense transmitted through bite of tsetse fly Naegleria Meningoencephalitis - cause: amoeba Naegleria fowleri, often infects children swimming in ponds or streams

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Nervous System Diseases Caused by Prions
Diseases of the CNS that progress slowly and cause spongiform degeneration are caused by prions (infectious proteins; proteinacious infectious particles) - sheep scrapie, transmissible mink encephalopathy, mad cow disease (bovine spongiform encepalopathy (BSE)), Creutzfeldt-Jakob disease, Kuru Diseases Caused by Unidentified Agents Chronic Fatigue Syndrome - Chronic fatigue syndrome may be caused by an unidentified infectious agent

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Chapter 23 - Microbial Diseases of the Cardiovascular and Lymphatic Systems
Structure & Function of the Cardiovascular & Lymphatic Systems: - cardiovascular system: transports blood through body tissues to deliver oxygen & nutrients and remove waste products o blood is a mixture of liquid plasma & solid formed elements o formed elements include:  red blood cells (erythrocytes): carry oxygen & some carbon dioxide in blood  white blood cells (leukocytes): fight infection  platelets: involved in blood clotting - lymphatic system: returns fluid lost by blood capillaries in between tissue cells (interstitial fluid) to blood o lymph capillaries are larger & more permeable than blood capillaries & readily pick up microorganisms & their products along with fluid (lymph) o lymph flows through lymph nodes containing immune cells o macrophages in lymph nodes clear lymph of infectious microorganisms o buboes: swollen lymph nodes due to infection

Bacterial Diseases of the Cardiovascular & Lymphatic Systems
Septicemia, Sepsis & Septic Shock - septicemia: multiplying bacteria in blood o ordinarily, bacterial growth in blood is prevented/inhibited by phagocytes & low iron content o if immune defenses fail, bacteria can lyse red blood cells & free iron-containing hemoglobin, increasing bacterial growth o lymphangitis (inflamed lymph vessels seen as red streaks under skin) - sepsis: bacteria in the blood; usually gram-negative rods o bacteria can enter blood from focal infection or through catheters or IV tubes - septic shock (gram-negative sepsis): drop in blood pressure caused by endotoxins o antibiotics may complicate condition (more endotoxin released by bacterial death) o recently gram-positive bacteria have been associated with septic shock - puerperal sepsis (puerperal fever or childbirth fever): nosocomial infection of the uterus as a result of childbirth or abortion o cause: Streptococcus pyogenes (primarily) o complications: peritonitis; septicemia o treatment: penicillin o prevention: disinfection of hands & instruments Bacterial Infections of the Heart - endocarditis: inflammation of endocardium & associated valves - subacute bacterial endocarditis: slow developing disease characterized by fever, weakness & heart murmur o cause: α-hemolytic streptococci (usually; also enterococci & staphylococci) o route of transmission: focal infection of teeth or tonsils travel through blood to
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heart (following dental procedures or surgery) o bacteria lodge in preexisting lesions of weakened heart valves due to congenital defects, rheumatic fever or syphilis o lesions produce blood clots that protect bacteria; clots may break off & block circulation or kidneys o over time heart valve function is impaired – fatal if untreated acute bacterial endocarditis: rapidly progressing endocarditis o cause: Staphylococcus aureus o treatment: penicillin; can be used prophylactically prior to dental surgery (if valve function weakened) pericarditis: bacterial infection & inflammation of pericardium o cause: Streptococcus pyogenes (usually)

Rheumatic Fever - cause: Streptococcus pyogenes - probably autoimmune complication of streptococcal infection (immune reaction against streptococcal M protein); repeated sore throats can renew attacks - progression: sore throat; arthritis & fever; subcutaneous nodules at joints; heart inflammation & valve damage; may cause death - common cause of death in children in early 1900s; incidence has declined in developed countries & is now rare with periodic localized outbreaks - complication: Sydenham’s chorea (St. Vitus’ dance) – flailing involuntary movement - treatment: penicillin (benzathine penicillin G) Tularemia - cause: Francisella tularensis (small gram-negative facultatively anaerobic pleomorphic rods) - mode of transmission: inhalation, ingestion of contaminated meat, contact with minor skin breaks, bites of small wild mammals (rabbits) or arthropods (deer flies, ticks) - bacteria are intracellular; survive phagocytosis - signs & symptoms: local inflammation & ulcer at infection site; enlarged lymph nodes; septicemia, pneumonia & abscesses throughout body - treatment: streptomycin, gentamicin; prolonged administration to prevent relapse - prevention: attenuated vaccine for high risk workers Brucellosis (undulant fever) - cause: Brucella species (small gram-negative aerobic rods) - mode of transmission: historically unpasteurized milk of cattle or goats; but more recently, through contact with diseased animal tissue o bacteria enter through abrasion in skin or mucous membranes - treatment: tetracycline & streptomycin for several weeks Anthrax - cause: Bacillus anthracis , a gram-positive aerobic rod - grazing animals contract disease after ingesting endospores (endospores can survive up to 60 years in soil & can be spread airborne in aerosols)
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mode of transmission: to humans by handling hides of infected animals o pulmonary anthrax: entry through the respiratory tract can cause pneumonia produces pustules that can progress to septicemia treatment: penicillin (may be ineffective due to persistent exotoxins) prevention: vaccine; boosters

Gangrene: death of soft tissue from loss of blood supply - ischemia (blocked blood flow) leads to necrosis (tissue death) & bacterial growth - gas gangrene results from anaerobic production of gases (carbon dioxide & hydrogen) by bacteria that swell tissues - cause: Clostridium perfringens (usually; also other Clostridium species) - Clostridium are gram-positive endospore-forming anaerobes - treatment: penicillin; surgical removal of necrotic tissue; amputation if necessary; hyperbaric oxygen chambers kill anaerobic clostridia Bacteria that cause systemic diseases by bites & scratches - Pasteurella multocida (gram-negative rod) o mode of transmission: dog and cat bites; can cause septicemia, pneumonia o treatment: penicillin & tetracycline - Cat-scratch disease o cause: Bartonella henselae (aerobic, gram-negative) o mode of transmission: dog and cat scratches or bites; possibly fleas or saliva o signs & symptoms: papule at infection site; swollen lymph nodes, malaise & fever; usually self-limiting Plague (known in middle ages as Black Death; killed ≥ 25% of European population) - cause: Yersinia pestis (gram-negative rod) - mode of transmission: rat flea (Xenopsylla cheopis) o normal host is rat, but can infect human host - progression: bubonic plague (buboes or swellings in lymphoid tissue); septicemic plague (bacteria multiplying in blood); pneumonic plague (bacteria move to lungs) - pneumonic plague easily spread by aerosols; usually fatal within 3 days - treatment: streptomycin, tetracycline - prevention: vaccine available for high risk workers Relapsing Fever - cause: Borrelia species (spirochetes) - signs & symptoms: fever, often > 105˚C; jaundice; red skin spots; relapse in 3-4 days Lyme Disease (Lyme Borreliosis) - cause: Borrelia burgdorferi (spirochete) - most common tickborne disease in US (10,000 annual cases) - mode of transmission: tick (Ixodes) bite; field mouse is reservoir - signs & symptoms: skin lesion spreads at site of bite, clearing in center; flu symptoms - complications: arthritis; occasionally heart & neurological abnormalities - treatment/prevention: several antibiotics effective (penicillin); vaccine available
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Typhus: caused by parasitic rickettsias transmitted by arthropod vectors - epidemic typhus: o cause: Rickettsia prowazekii o mode of transmission: human louse (Pediculus humanus); scratching bite o signs & symptoms: prolonged high fever; stupor; small red spots from subcutaneous hemorrhaging (bacteria invade endothelium & cause inflammation) o treatment/prevention: tetracycline, chloramphenicol; vaccine available - endemic murine typhus: similar to epidemic typhus but less severe o cause: Rickettsia typhi o mode of transmission: rat flea (Xenopsylla cheopis) o treatment: tetracycline, chloramphenicol - spotted fevers (Rocky mountain spotted fever): o cause: Rickettsia rickettsii  tick parasite passed from one generation of ticks to another o mode of transmission: bite of wood tick or dog tick (Dermacentor species) o signs & symptoms: rash similar to measles on palms & soles (unlike measles); fever & headache o treatment/prevention: tetracycline, chloramphenicol; vaccine available

Viral Diseases Of The Cardiovascular And Lymphatic Systems
Burkitt’s Lymphoma - most common childhood cancer in Africa - cause: Epstein-Barr (EB) virus o nasopharyngeal carcinoma also associated with EBV Infectious Mononucleosis - cause: Epstein-Barr (EB) virus - multiplies in the parotid glands and is present in saliva - causes the proliferation of atypical lymphocytes (mononucleoses); B cells with lobed nuclei which are then attacked by cytotoxic T cells - often asymptomatic & self-limiting; virus remains latent in some B cells - route of transmission: saliva - diagnosis: fluorescent antibodies against EB virus Viral Hemorrhagic Fevers: - yellow fever caused by yellow fever virus & transmitted by mosquito (Aedes aegypti) o symptoms: fever, chills headache, nausea & vomiting, jaundice o prevention: vaccine available with few side effects - dengue caused by dengue virus & transmitted by mosquito (Aedes aegypti) o symptoms: fever, rash, severe muscle & joint pain; possible shock - treatment: no specific treatment; treatments may address symptoms (IV fluids to replace water/electrolytes; transfusion for bleeding) - emerging hemorrhagic fevers: Ebola, hantavirus pulmonary syndrome

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Protozoan Diseases of the Cardiovascular and Lymphatic Systems
American Trypanosomiasis (Chagas’ Disease) - cause: Trypanosoma cruzi - mode of transmission: arthropod reduviid bug (kissing bug); wild animal reservoir - can result in heart & nerve damage; enlarged GI tract organs due to lack of peristalsis Toxoplasmosis - cause: Toxoplasma gondii (sporozoan) - undergoes sexual reproduction in intestinal tract of domestic cats, and oocysts are eliminated in cat feces; oocysts can be ingested by cattle and other animals - sporozoites reproduce to form either tissue-invading tachyzoites or bradyzoites - mode of transmission: to humans by ingesting tachyzoites or tissue cysts with bradyzoites in undercooked meat from infected animal or contact with cat feces - often mild symptoms; subclinical infections common - congenital infections can occur – can result in stillbirth or fetal brain & eye damage - signs & symptoms: severe brain damage or vision problems - treatment: pyrimethamine with sulfadiazene Malaria - cause: any one of four species of Plasmodium - mode of transmission: bite of Anopheles mosquito; occasionally unsterilized needles or infected blood transfusions - signs & symptoms: chills, fever, vomiting, and headache; at intervals of 2-3 days - sporozoites from mosquito saliva reproduce in the liver and release merozoites into the bloodstream, where they infect red blood cells and produce more merozoites; RBCs rupture & release toxins that cause recurrent symptoms → cycles in blood - anemia results from loss of RBCs; enlargement of liver & spleen - recovery provides some resistance; people with sickle cell trait are relatively resistant - diagnosis: identification of infected RBCs in blood smears; serology - treatment: once quinine; now derivatives primaquine & chloroquine Leishmaniasis - cause: Leishmania species o Leishmania donovani causes visceral leishmaniasis with symptoms similar to malaria where internal organs are invaded o Leishmania tropica & Leishmania braziliensis cause lesions of skin or mucous membranes - mode of transmission: bite of female sandflies; small mammal reservoir - treatment: drugs with antimony (toxic metal); amphotericin B; recently, miltefosine Babesiosis: tickborne disease resembling malaria (chills, fever) - cause: Babesia microti - microbes multiply in & lyse RBCs; may cause anemia - frequently subclinical; serious in immunocompromised

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Helminthic Diseases of the Cardiovascular and Lymphatic Systems
Schistosomiasis - cause: Schistosoma species (small fluke) - signs & symptoms: schistosome eggs lodge in tissue & cause inflammation & tissue damage (granulomas) - diagnosis: detection of flukes or eggs in feces, urine; serology - treatment: praziquantel, oxamniquine Swimmer’s Itch - cause: larvae of schistosomes (cercariae) - signs & symptoms: local inflammation (cercariae do not progress beyod skin & only mature in wild fowl)

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Chapter 24 - Microbial Diseases Of The Respiratory System
Structure And Function Of The Respiratory System - upper respiratory system: nose & pharynx & associated structures o coarse hairs in the nose filter large particles from entering air o ciliated mucous membranes of the nose & throat trap & remove airborne particles o lymphoid tissue, tonsils, and adenoids provide immunity to certain infections. o alveolar macrophages in lungs & IgA in respiratory mucus kill & trap bacteria - lower respiratory system: larynx, trachea, bronchial tubes & alveoli o ciliary escalator of the lower respiratory system helps prevent microorganisms from reaching the lungs Normal Flora Of The Respiratory System - upper respiratory system: Streptococcus, Neisseria, Haemophilus , and Bacteroides species o pathogenic species normally found include Staphylococcus aureus, Corynebacterium diphtheriae, Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae - lower respiratory system: very few, due to efficient cleansing of mucous membranes by ciliated cells

Bacterial Diseases of The Upper Respiratory System
Streptococcal Pharyngitis (Strep Throat) - cause: Group A Beta hemolytic (Streptococcus pyogenes) - S. pyogenes is resistant to phagocytosis & produces hemolysins & streptokinase - mode of transmission: respiratory secretions - signs & symptoms: local inflammation & fever; tonsillitis & otitis media may result - treatment: penicillin Scarlet Fever - cause: Streptococcus pyogenes that produces an erythrogenic toxin (due to bacteriophage infection) - signs & symptoms: rash begins as a facial erythema sparing the area around the mouth, and spreads to the trunk and limbs o the classical appearance is described as a punctate erythema, and is followed by extensive peeling, which may continue for 2-3 weeks - mode of transmission: inhalation of respiratory secretions - treatment: penicillin Diphtheria - cause: exotoxin from Corynebacterium diphtheriae (gram-positive aerobic rod) - signs & symptoms: membrane in the throat (pseudomembrane) forms containing fibrin and dead human and bacterial cells and can block passage of air o exotoxin damages protein synthesis and heart liver kidney or nerve damage o cutaneous diphtheria produces slow healing skin ulcerations
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treatment: penicillin, erythromycin to kill bacteria; antitoxin prevention: DTaP vaccine in US; contains diphtheria toxoid (inactivated toxin) diphtheria infection is still common in some developing countries

Otitis Media (middle ear infection/earache) - cause: usually Streptococcus pneumoniae (also H. influenzae, S. pyogenes, S. aureus) o often a complication of nose & throat infections - signs & symptoms: pus build pressure against eardrum causing inflammation & pain - treatment/prevention: broad-spectrum penicillin (amoxicillin); vaccines in development

Viral Disease of the Upper Respiratory System
Common cold - cause: usually rhinoviruses; also coronaviruses & others (> 200 viruses) - signs & symptoms: sneezing, excessive nasal secretion, congestion - complications: sinusitis, lower respiratory tract infections, laryngitis, otitis media - mode of transmission: possibly fomites; possibly airborne - treatment: none; self-limiting

Bacterial Diseases of the Lower Respiratory System
Pertussis (whooping cough) - cause: Bordetella pertussis (aerobic gram-negative coccobacillus) - signs & symptoms: catarrhal stage (resembles common cold); paroxysmal stage (prolonged often violent coughing (whooping sound between coughs); mucus accumulation; can last 1-6 weeks); convalescence stage (persistent cough for months; possible brain damage in infants) - treatment: erythromycin - prevention: DTaP vaccine Tuberculosis - cause: Mycobacterium tuberculosis , a slow growing acid-fast rod - mode of transmission: primarily inhalation of bacteria - high lipid content in cell wall accounts for acid-fastness and its resistance to drying and disinfectants - may actually reproduce in macrophages - causes lesion in lungs (tubercles), which consists of dead bacteria and macrophages (Ghon complex); if it breaks, can spread to other parts of the body - diagnosis: tuberculin skin test (tests for delayed type hypersensitivity due to sensitized T cells against purified bacterial protein); + = red area around injection o not definitive; may indicate immunity from prior infection o supplement with acid-fast stain; fluorescent antibody or PCR - Mycobacterium bovis causes bovine TB; can infect humans by unpasteurized milk - treatment: isoniazid, rifampin, pyrazinamide with ethambutol, streptomycin o treatment for months up to 1-2 years - prevention: BCG vaccine years (live, attenuated M. bovis)

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Bacterial pneumonias - Pneumococcal pneumonia o cause: Streptococcus pneumoniae (encapsulated) o signs & symptoms: high fever, breathing difficulty, chest pain; lungs have red appearance due to blood vessel dilation & blood cells in alveoli o diagnosis: x-ray; α-hemolysis, optochin sensitivity & bile solubility in culture o treatment: penicillin o prevention: purified capsular & conjugated pneumococcal vaccines - Haemophilus influenzae pneumonia o cause: Haemophilus influenzae (gram-negative coccobacillus) o predisposing factors: alcoholism, poor nutrition, cancer, diabetes o treatment: 2nd generation cephalosporins (due to penicillinases) - Mycoplasmal pneumonia (primary atypical or walking pneumonia) o cause: Mycoplasma pneumoniae o signs & symptoms: low-grade fever, cough, headache o diagnosis: PCR; serology; bacteria form colonies with fried-egg appearance on rich medium o treatment: tetracycline Legionellosis o cause: Legionella pneumophila (aerobic gram-negative rod) o bacteria isolated from natural waters; can grow in water cooling towers, spas, showers, hospital water lines o signs & symptoms: high fever, cough, pneumonia symptoms o treatment: erythromycin, azithromycin Psittacosis (Ornithosis) o cause: gram-negative obligate intracellular parasite Chlamydia psittaci o mode of transmission: contact with bird droppings o signs & symptoms: fever, headaches, and chill. o bacterium is obligate intracellular parasite; must be isolated in embryonated eggs, mice, or cell culture; identification by FA techniques or complement fixation o treatment: tetracycline; no effective immunity is produced Chlamydial Pneumonia o cause: Chlamydia pneumoniae o mode of transmission: person to person o treatment: tetracycline Q Fever o cause: obligate intracellular parasite Coxiella burnetii o mode of transmission: unpasteurized milk or inhalation of aerosols in dairy barns o signs & symptoms: subclinical; fever, chills, chest pain, & headache o treatment: tetracycline o diagnosis: culture in embryonated eggs or cell culture.

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Other Bacterial Pneumonias o cause: gram + bacteria (Staphylococcus aureus, Streptococcus pyogenes); gram – bacteria (Klebsiella pneumoniae, Pseudomonas & Enterobacter species, Escherichia coli) o rare in healthy individuals; mostly affect immunocompromised, debilitated o Klebsiella pneumoniae can cause a severe lobar pneumonia with a risk of lung abscesses & possible lung damage; individuals with chronic alcoholism, diabetes, COPD are at greatest risk

Viral Diseases of Lower Respiratory System
Viral pneumonia: can occur as a complication of influenza, measles or chickenpox - cause: generally unknown viruses (respiratory syncytial virus (RSV) is the most common cause of pneumonia in infants) Influenza - cause: Influenzavirus o virus is enveloped with hemagglutinin (H) & neuraminidase (N) spikes o H spikes allow viral attachment to host cells; N spikes may help virus exit infected cells; antibodies mainly produced against H spikes o strains differentiated by antigenic differences in H & N spikes; also, by antigens in protein coat (types A, B & C) o identification of viral isolates by hemagglutination & fluorescent antibodies (FA) o antigenic shift: major changes in spike antigens – previous immunity usually fails o antigenic drift: minor annual changes in spike antigens; vaccines less effective - symptoms: chills, fever, headache, muscular aches - treatment: rest, adequate fluids; antiviral drugs may shorten duration of symptoms by ~ 1 day... amantadine & rimantidine for A-type influenza; zanamivir and oseltamivir (Relenza™ & Tamiflu™) are inhibitors of neuraminidase that prevent viral release from host cells; drugs must be administered promptly (within 2 days) after infection o antibiotics should not be used unless there is diagnosed bacterial complication - prevention: annual vaccines due to mutation of virus

Fungal Diseases of the Lower Respiratory System
Histoplasmosis - cause: inhaling airborne conidia of Histoplasma capsulatum o fungal conidia present in bird & bat droppings - signs & symptoms: generally subclinical respiratory infection but can progress to severe generalized disease - treatment: amphotericin B, itraconazole Coccidioidomycosis - cause: inhaling airborne arthrospores of Coccidioides immitis o can be spread by wind (dust storms) - signs & symptoms: generally subclinical; can disseminate to tissues & spinal fluid - treatment: ketoconazole or itraconazole; amphotericin B for severe cases
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Pneumocystis pneumonia - cause: Pneumocystis carinii o found in healthy lungs but causes disease in immunosuppressed (AIDS patients) - thick-walled cysts in alveoli that rupture & releases intracystic bodies; released bodies develop into trophozoites (asexual) & cysts (sexual stage) - treatment: trimethoprim-sulfamethoxazole; pentamidine isethionate Blastomycosis (North American Blastomycosis) - cause: Bastomyces dermatitidis (dimorphic fungus in soil) - signs: spreads from lungs; forms cutaneous ulcers, abscesses & tissue death - treatment: amphotericin B

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Chapter 25: Microbial Diseases of the Digestive System
Normal Flora of Digestive System: mostly in large intestine - includes Lactobacillus & Bacteroides species (anaerobes) & E. coli, Enterobacter, Klebsiella & Proteus species (facultative anaerobes)

Bacterial Diseases of the Mouth
Dental caries (tooth decay) - cause: usually Streptococcus mutans - bacteria metabolize sucrose (many other carbohydrates cannot be used by these bacteria) in food to form dextran & lactic acid - dextran forms dental plaque - acid from fermentation destroys tooth enamel - prevention: restricting ingestion of sucrose (sugar) & removal of plaque (brush, floss) - periodontitis due to inflammatory response to bacteria growing on gums o can cause bone destruction & tooth loss

Bacterial Diseases of Lower Digestive System
Staphylococcal Food Poisoning - cause: Staphylococcus aureus - produces enterotoxin (exotoxin) released into improperly stored food - mode of transmission: consumption of foods with high osmotic pressure, foods prepared in advance & not prepared (cooked) properly - signs & symptoms: nausea, vomiting, diarrhea - diagnosis: isolation and identification of bacteria from food; serology for toxin Shigellosis (Bacillary Dysentery) - cause: four species of Shigella - virulent species produce exotoxins (Shiga toxin) that kill mucosal cells - symptoms: blood & mucus in stools, abdominal cramps, and fever o infections by S. dysenteriae cause ulceration of the intestinal mucosa - diagnosis: isolation and identification of the bacteria from rectal swabs Salmonellosis (Salmonella gastroenteritis) - cause: Salmonella bacteria - mode of transmission: consumption of poultry, egg or egg products not cooked properly or not stored properly - signs & symptoms: fever, nausea, abdominal pain & diarrhea o septicemia may occur in infants & elderly; exotoxin may cause fever - diagnosis: isolation and identification of the bacteria from food &/or feces - prevention: heating food to 68˚C will kill Salmonella Typhoid Fever - cause: Salmonella typhi - mode of transmission: contact with contaminated human feces
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signs & symptoms: 2-3 weeks of high fever, headache, diarrhea after 2 week incubation period S. typhi may remain in the gallbladder of carriers treatment/prevention: several weeks of cephalosporins; vaccine available for high risk

Cholera - cause: Vibrio cholerae (slightly curved gram-negative rod) o enterotoxin produced by some serogroups causes excretion of water & electrolytes with dead mucosal cells (rice water stools) - mode of transmission: contact with food items associated with poorly sanitized water - signs & symptoms: violent vomiting with significant fluid loss - treatment: tetracyclines & replacement of lost fluids & electrolytes Vibrio gastroenteritis - other serogroups of Vibrio produce mild diarrhea - cause: V. parahaemolyticus & V. vulnificus o symptoms within a day; recovery in a few days o contracted by consumption of contaminated crustaceans & mollusks Escherichia coli Gastroenteritis - cause: enterotoxigenic, enteroinvasive, or enterohemorrhagic strains of E. coli - epidemic diarrhea in nurseries, traveler's diarrhea, endemic diarrhea in less developed countries, & hemorrhagic colitis - signs & symptoms: enterohemorrhagic E. coli (E. coli O157:H7) produces Shiga toxins that cause inflammation and bleeding of the colon, including hemorrhagic colitis; Shiga toxins can also cause hemolytic uremic syndrome in kidneys - treatment: self-limiting in adults; no chemotherapy required Campylobacter Gastroenteritis - cause: Campylobacter species (usually Campylobacter jejuni); gram negative microaerophilic curved rods - mode of transmission: consumption of contaminated poultry; sometimes red meat - Campylobacter is the second most common cause of diarrhea in the U.S. Helicobacter Peptic Ulcer Disease - cause: Helicobacter pylori - Helicobacter pylori produces ammonia, which neutralizes stomach acid; the bacteria colonize the stomach mucosa and cause peptic ulcer diseases - treatment: bismuth & several antibiotics may be useful in treating peptic ulcer disease Yersinia Gastroenteritis - cause: Y. enterocolitica and Y. pseudotuberculosis - mode of transmission: meat and milk; Yersinia can grow at refrigerator temperature Clostridium perfringens Gastroenteritis - cause: Clostridium perfringens
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endospores survive heating and germinate when foods (usually meats) are stored at room temperature exotoxin produced by bacteria growing the intestines is responsible for symptoms diagnosis: isolation and identification of bacteria is stool samples.

Bacillus cereus Gastroenteritis - cause: soil saprophyte Bacillus cereus - signs & symptoms: diarrhea, nausea, and vomiting - mode of transmission: endospores in undercooked foods

Viral Diseases of the Digestive System
Mumps - cause: mumps virus - mode of transmission: saliva & respiratory secretions - signs & symptoms: painful swelling of parotid glands - prevention: MMR vaccine Cytomegalovirus Inclusion Disease - cause: Cytomegalovirus (CMV) - mode of transmission: personal/sexual contact, transfusion, transplants - generally asymptomatic; can damage fetus if acquired during pregnancy; can lead pneumonia in immunosuppressed - treatment: ganciclovir Hepatitis: inflammation of the liver - symptoms: loss of appetite, malaise, fever, and jaundice - viral causes of hepatitis include hepatitis viruses, Epstein-Barr virus (EBV), and cytomegalovirus (CMV). - Hepatitis A o cause: hepatitis A virus (HAV) o 50 % of all cases are subclinical. o HAV is ingested in contaminated food or water, grows in the cells of the intestinal mucosa, and spreads to the liver, kidneys, and spleen in the blood o the virus is eliminated with feces o incubation period 2-6 weeks; the period of disease is 2-21days, and recovery is complete in 4-6 weeks o diagnosis: based on tests for IgM antibodies o prevention: passive immunization can provide protection; vaccine is available. - Hepatitis B o cause: hepatitis B virus (HBV) causes hepatitis B, which is frequently serious o HBV is transmitted by blood transfusions, contaminated syringes, salvia, sweat, breast milk, and semen o blood is tested for HBsAg before being used in transfusion o the average incubation period is 3 months; recovery is usually complete, but some patients develop a chronic infection or become carriers o prevention: vaccine against HBsAg is available.
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Hepatitis C o cause: hepatitis C virus (HVC) o mode of transmission: via blood o average incubation period is 2-22 weeks: the disease is usually mild, but some patients develop chronic hepatitis o blood is tested for HCV antibodies before being used in transfusion. Hepatitis D o cause: hepatitis D virus (HDV); RNA virus that uses HBsAg as a coat Hepatitis E o cause: Hepatitis E virus (HEV) is spread by the fecal-oral route o there is evidence of the existence of hepatitis types F and G.

Viral Gastroenteritis - Viral Gastroenteritis is most often caused by a rotavirus or the human calciviruses, better known as the Norwalk or norovirus family of viruses Protozoan Diseases Of The Digestive System Giardiasis - cause: Giardia lamblia - mode of transmission: contaminated water; grows in the intestine of humans and wild animals - symptoms: malaise, nausea, flatulence, weakness, and abdominal cramps that persist for weeks - diagnosis: presence of the protozoa in the small intestines - treatment: metronidazole or quinacrine Cryptosporiosis - cause: Crytosporidium parvum - causes diarrhea; in immunosuppressed patients, the disease is prolonged for months - mode of transmission: contaminated water - diagnosis: identification of oocysts in feces - treatment: fluids Cyclospora Diarrheal Infection - cause: C. cayetanensis - causes diarrhea - mode of transmission: contaminated produce - diagnosis: identification of oocysts in feces - treatment: TMP-SMZ Amoebic Dysentery (Amoebiasis) - cause: Entamoeba histolytica growing the large intestine - amoeba feeds on RBCs and GI tract tissues; severe infections result in abscesses - diagnosis: observing trophozoites in feces and by serology - treatment: metronidazole & iodoquinol
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Helminthic Diseases Of The Digestive System Tapeworm Infestation - cause: tapeworms (Taenia species) o includes beef tapeworm (Taenia saginata) & pork tapeworm (Taenia solium); fish tapeworm is Diphyllobothrium latum) - mode of transmission: eating undercooked beef, pork, or fish with encysted larvae o scolex attaches to the intestinal mucosa of humans (the definitive host) and matures into an adult tapeworm o eggs are shed in the feces and must be ingested by an intermediate host o eggs ingested by animals (cow, pig, fish) & eggs hatch into larval form (cystercerci) that lodges in animal’s muscles - can be undiagnosed in a human - diagnosis: observing eggs or proglottids in feces - treatment: niclosamide Nematode Infestations - humans are the definitive host for pinworms, Enterobius vermicularis o the disease is acquired by ingesting Enterobius eggs - hookworm larvae bore through skin and migrate to the intestine to mature into adults o in the soil, hookworm larvae hatch from eggs shed in feces - Ascariasis is caused by Ascaris lumbricoides; adults live in human intestines o the disease is acquired by ingesting Ascaris eggs. Trichinosis - cause: Trichinella spiralis - larvae encyst in muscles of humans and other mammals - mode of transmission: ingesting undercooked meat (primarily pork) o adults mature in the intestines & lay eggs; new larvae migrate to invade muscles - symptoms: fever, swelling around the eyes, gastrointestinal upset - diagnosis: muscle biopsy… no egg stage where larvae are laid, & serology tests - treatment: mebendazole to kill worms & corticosteroids to control inflammation

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Chapter 26 - Microbial Diseases of the Urinary and Reproductive Systems
Bacterial Diseases of the Urinary System
Urethritis, cystitis, and ureteritis – Lower urinary tract Pyelonephritis – Kidney inflammation

Cystitis: inflammation of the urinary bladder - common in females because of a short urethra - mode of transmission: careless personal hygiene, sexual intercourse, and urinary tract infections - cause: gram-negative rods are the most common cause (usually E. coli); also Staphylococcus saprophyticus - symptoms: dysuria and pyuria - treatment: antibiotics - type depends on the etiologic agent Pyelonephritis: inflammation of the kidneys - usually a complication of a lower urinary tract infection and involves nephrons and renal pelvis - cause: usually Escherichia coli (75%) - complications: chronic condition causes formation of scar tissue - treatment: extended course of IV broad-spectrum antibiotics Leptospirosis - cause: spirochete Leptospira interrogans - mode of transmission: to humans by urine-contaminated water - signs & symptoms: chills, fever, headache, jaundice. - diagnosis: isolation and identification by serological tests - treatment: usually penicillin, but it is often not effective

Diseases of the Reproductive System
Bacterial Diseases of the Reproductive System
Gonorrhea - cause: Neisseria gonorrhoeae (gram-negative diplococcus) - attaches to mucosal cells of oral-pharyngeal area, genitals, eyes & rectum by fimbriae - signs & symptoms: painful urination & discharge in males; subclinical to abdominal pain in females - complications: infections of joints, heart (gonorrheal endocarditis), meninges (gonorrheal meningitis), eyes, pharynx, etc. - untreated gonorrhea (especially with chlamydial coinfection) can lead to pelvic inflammatory disease (PID); salpingitis (inflamed uterine tubes) can cause sterility - ophthalmia neonatorum: bacteria pass birth canal; possible fetal blindness - pharyngeal & anal gonorrhea not uncommon - diagnosis: gram stain and culture (urethral smear or cervical swabs); ELISA
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treatment: traditionally penicillin, with increased dosages due to resistance; ceftriaxone (cephalosporin) has shown good results o also, tetracycline to treat possible concurrent Chlamydia infection

Nongonococcal Urethritis (NGU) - includes any inflammation of urethra not caused by Neisseria gonorrhoeae - cause: usually Chlamydia trachomatis o also Ureaplasma urealyticum & Mycoplasma hominis - signs & symptoms: often lacking; possibly uterine tube inflammation & may cause sterility in females & males (epididymitis) - Chlamydia trachomatis is also a cause of lymphogranuloma venereum (inflammation of lymph nodes) in tropical regions - Chlamydia trachomatis can be transmitted to infants’ eyes at birth - diagnosis: detection of chlamydial DNA in urine - treatment: tetracycline, doxycycline; azithromycin Syphilis - cause: Treponema pallidum (spirochete) - mode of transmission: direct contact; bacteria can invade intact mucosal membranes or penetrate through breaks in the skin - signs & symptoms: primary stage - asymptomatic chancre at the site of the lesion; secondary stage - rash over skin and mucous membranes; tertiary stage may appear after 2-3 years latency... includes lesions (gummas) on organs that may ulcerate, may cause damage to palate (affects speech), weakening of aorta, loss of motor control & dementia - congenital syphilis: bacteria may be transmitted across placenta to fetus; may cause neurological damage to fetus in latent period or stillbirth in initial stages - diagnosis: microscopic visualization (primary stage); serological tests (treponemal & nontreponemal); T. pallidum has not been cultured in vitro o Rapid Plasma Reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test, along with fluorescent treponemal antibody absorption (FTA-ABS) test - treatment: benzathine penicillin; for penicillin-sensitive individuals, doxycycline & tetracycline

Viral Diseases of the Reproductive System
Genital Herpes - cause: herpesvirus (HSV-2 usually; also HSV-1) - painful urinary and genital symptoms - can pass to fetus in utero or at birth - treatment: no cure; acyclovir can control symptoms Genital Warts - cause: human papillomavirus (HPV) - a few serotypes cause cervical cancer in females & penile cancer in males - treatment: topical popdofilox & imiquimod (stimulates interferons)
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Fungal Disease of the Reproductive System Candidiasis - cause: Candida albicans (usually) when pH of vagina increases o C. albicans causes nongonococcal urethritis (NGU) in males & vulvovaginal candidiasis in females - predisposing factors: pregnancy, diabetes, tumors, broad-spectrum antibiotic therapy - signs & symptoms: irritation, itching, discharge - diagnosis: fungal observation & isolation from lesions - treatment: topical antifungals (clotrimazole, miconazole); oral fluconazole Protozoan Disease of the Reproductive System Trichomoniasis - cause: Trichomonas vaginalis when pH of vagina increases - protozoans seen in urine - treatment: oral metronidazole

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