Ch 23: Microbial Diseases of the Cardiovascular and Lymphatic Systems

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1

lymphatic system

  • Plasma leaves blood capillaries to become interstitial fluid
  • Lymph capillaries transport interstitial fluid (lymph) to lymph vessels (lymphatics) and lymph nodes
  • Picks up microorganisms and infectious agents
  • Lymph nodes contain fixed macrophages, B cells, and T cells
  • Buboes: swollen lymph nodes
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Septicemia

Acute illness due to the presence of replicating pathogens or their toxins in the blood

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Sepsis

Systemic inflammatory response syndrome (SIRS)

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Septic shock

Sepsis and uncontrollable decreased blood pressure•Severe sepsis

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Severe sepsis

Decreased blood pressure and dysfunction of at least one organ•L

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Lymphangitis

Inflamed lymph vessels

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Gram-Negative Sepsis

  • endotoxin shock
  • Endotoxins (lipopolysaccharides [LPS] ) cause a severe drop in blood pressure (systemic vasodialation)
  • Antibiotics can worsen the condition by killing bacteria
  • Treatment involves neutralizing the LPS components and inflammatory-causing cytokines
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Gram-Positive Sepsis

  • Potent exotoxins that cause toxic shock syndrome. hemolysin, exfoliative toxin, enterotoxin, and toxic-shock syndrome toxin-1 (TSST-1) produced by Staphylococcus aureus
  • Hospital-acquired infections•Enterococcus faecium and Enterococcus faecalis. Inhabit the colon, colonize wounds and the urinary tract•Resistant to many antibiotics
  • Group B streptococci (GBS)•Streptococcus agalactiae. Found in the vagina, intestines, rectum. Neonatal sepsis
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Puerperal Sepsis

  • puerperal fever, childbirth fever, and postpartum infection
  • Caused by Streptococcus pyogenes (Group A Strep, GAS)
  • mother is infected during childbirth•Infects the uterus and progresses to an infection of the abdominal cavity (peritonitis)
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Endocarditis

  • Inflammation of the endocardium
  • Subacute bacterial endocarditis: Impairs function of the heart valves and Alpha-hemolytic streptococci from an oral or tonsil infection
  • Acute bacterial endocarditis: Most commonly caused by S. aureus
  • Pericarditis: Inflammation of the sac around the heart. Fluid buildup is called pericardial effusion and can lead to cardiac tamponade. Commonly caused by Streptococci spp.
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Rheumatic Fever

  • Inflammation of heart valves
  • Occurs if strep throat or scarlet fever is not properly treated
  • Autoimmune complication of Streptococcuspyogenes (GAS) infections
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Tularemia

  • Can cause endocarditis
  • Caused by Francisella tularensis: Gram-negative rod
  • Zoonosis- Transmitted from rabbits and deer by deer flies and ticks. rabbit fever or deer fly fever
  • Bacteria reproduce in phagocytes
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Brucellosis (Undulant Fever)

  • Transmitted via unpasteurized milk and cheese from infected animals or contact with fluids from infected animals
  • Can cause endocarditis
  • Brucella spp., B. abortus, B. suis, B. melitensis
  • Undulating fever spikes to 40oC each evening
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Anthrax

  • Bacillus anthracis: Gram-positive, endospore-forming aerobic rod
  • Found in soil, cattle are routinely vaccinated
  • Treated with ciprofloxacin (DNA replication inhibition) or doxycycline (protein synthesis inhibition)
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Anthrax types

  • Cutaneous anthrax: Endospores enter through minor cut - 20% mortality
  • Gastrointestinal anthrax: Ingestion of undercooked, contaminated food - 50% mortality
  • Inhalational (pulmonary) anthrax: Inhalation of endospores, germinate in lungs, enter bloodstream and replicate, septic shock – 100% mortality
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Ischemia:

Necrosis:

Gangrene:

Gas gangrene

  • loss of blood supply to tissue
  • death of tissue
  • death of soft tissue
  • Clostridium perfringens, gram-positive, endospore-forming anaerobic rod, grows in necrotic tissue.Treatment includes surgical removal of necrotic tissue and/or use of hyperbaric chamber
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Plague

  • yersinia pestis: Gram-negative rod
  • Transmitted by the rat flea
  • Endemic to rats, ground squirrels, and prairie dogs
  • Bacteria blocks the flea's digestive tract. Flea bites the host and ingested blood is regurgitated into the host.
  • Bacteria enter the bloodstream and proliferate in the lymph tissue. Cause intense swellings called buboes
  • Antibiotics can treat infection
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Plague ilnesses

  • Bubonic plague: Bacterial growth in the blood and lymph•Most common form; 50–75% mortality rate
  • Septicemic plague: Septic shock due to bacteria in the blood
  • Pneumonic plague: Bacteria in the lungs. spread by airborne droplets. Near 100% mortality rate
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Lyme Disease

  • Causative agent: Borrelia burgdorferi
  • Reservoir: deer
  • Vector: ticks
  • First symptom: bull’s-eye rash
  • Second phase: irregular heartbeat, encephalitis
  • Third phase: arthritis
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Typhus

  • Rickettsia sp.
  • Obligate intracellular parasites•In endothelial cells of the vascular system
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Rocky Mountain spotted fever

  • (tickborne typhus) Caused by Rickettsia rickettsii
  • Measles-like rash, except that the rash also appears on palms and soles
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Infectious Mononucleosis (Mono)

  • Epstein-Barr virus (HHV-4)
  • Transmitted via saliva (kissing, sharing drinks)
  • Characterized by proliferation of monocytes and large lobed lymphocytes in the blood
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Burkitt’s Lymphoma

  • Epstein-Barr virus (HHV-4)
  • Nasopharyngeal carcinoma
  • Cancer in immunosuppressed individuals and in malaria and AIDS patients
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Cytomegalovirus Infections

  • Cytomegalovirus (HHV-5)
  • Infected cells swell
  • Latent in white blood cells
  • May be asymptomatic or mild
  • Transmitted across the placenta; may cause mental retardation
  • Transmitted sexually, by blood, or by transplanted tissue
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Ebola hemorrhagic fever

  • Spread by contact with infected body fluids
  • Damages blood vessel walls and interfere with coagulation
  • Blood leaks into surrounding tissue
  • Mortality rate of 90%
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Chagas’ Disease

  • Also called American trypanosomiasis
  • Causative agent: Trypanosoma cruzi
  • Feeds on blood and reproduces in the circulatory and lymphatic systems
  • Reservoir: rodents, opossums, armadillos
  • Vector: reduviid bug
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Toxoplasmosis

  • Causative agent: Toxoplasma gondii
  • Transmission•Ingesting undercooked meat
  • Contact with cat feces
  • Congenital infection: Stillbirth or neurological damage
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Malaria

  • Four species of causative agents:•Plasmodium vivax (benign malaria), P. ovale (benign malaria), P. malariae (benign malaria), P. falciparum (malignant malaria)
  • Vector: Anopheles mosquito•Definitive host: Anopheles mosquito
  • Treatment•Artemisinin, Chloroquine, Malarone, Mefloquine