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Lecture 15: Microbial diseases of the cardiovascular and lymphatic system Edith Porter, M.D. 1.

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Presentation on theme: "Lecture 15: Microbial diseases of the cardiovascular and lymphatic system Edith Porter, M.D. 1."— Presentation transcript:

1 Lecture 15: Microbial diseases of the cardiovascular and lymphatic system Edith Porter, M.D. 1

2 2  Cardiovascular and lymphatic systems  Bacterial diseases  Sepsis and septic shock, infections of the heart, rheumatic fever, systemic diseases caused by bites and scratches, vector transmitted diseases  Viral diseases  Hemorrhagic fevers  Protozoan diseases  Malaria, Chagas disease  Helminthic diseases  Schistosomiasis

3  Blood (plasma and formed elements)— Transports nutrients to and wastes from cells  Plasma leaves blood system to become interstitial fluid  Lymph capillaries—Transport interstitial fluid to blood  Lymph nodes—Contain macrophages, dendritic cells, B cells and T cells 3

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5  Septicemia  Presence of bacteria in blood with severe symptoms  Sepsis  Bacteria present (and proliferating) in blood and dissemination into various with organ dysfunction  Induces a systemic inflammatory response syndrome  Severe sepsis  Sepsis + decreased blood pressure  Septic shock  Sepsis + low blood pressure cannot be controlled 5

6  Lymphangitis  Inflamed lymph vessels accompanying septicemia and septic shock 6

7  Gram-negative sepsis  Endotoxins (LPS) induces cytokine release by macrophages and subsequently causes blood pressure to decrease  Antibiotics can worsen condition by killing bacteria and liberating endotoxin  Gram-positive sepsis  Less often  Less severe  Lipoteichoic acids in the gram positive cell wall can also induce cytokine release and symptoms of sepsis but to a lesser degree  Mostly observed during nosocomial infections ▪ Staphylococcus aureus ▪ Enterococcus faecium and E. faecalis  Puerperal spesis 7

8  Endocarditis  Inflammation of the endocardium  Subacute bacterial endocarditis  Alpha-hemolytic streptococci from mouth  Acute bacterial endocarditis  Staphylococcus aureus from mouth  Pericarditis  Streptococci 8

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11  Inflammation of heart valves and joints  Autoimmune complication of Streptococcus pyogenes infections 11

12  Brucella, gram-negative rods that grow in phagocytes  Granulomas form  If bacteria are not controlled they can reenter the bloodstream andcause recurrent  B. abortus (elk, bison, cows)  B. suis (swine)  B. melitensis (goats, sheep, camels)  Undulating fever that spikes to 40°C each evening  Transmitted via milk from infected animals or contact with infected animals 12

13 13  Bartonella henselae: cat-scratch disease  Pasteurella multocida: animal bites /md/pictures22/dermnet/cat_scr atch_disease_8.jpg

14  Normal microbiota of the upper respiratory tract of a number of animals  A frequent cause of opportunistic infections in domestic livestock  Usually acquired by humans from the bite or scratch of a dog or cat  Infection develops at the site of the wound and can spread via the lymphatics or via blood stream to a number of other organs  Virulent strains are encapsulated, but no other virulence factors are known  The organism is unusually sensitive to penicillin 14

15  Epidemic typhus  Rickettsia prowazekii  Reservoir ▪ Rodents  Vector ▪ Lice (Pediculus humanus corporis)  Transmitted when louse feces is rubbed into bite wound  Rocky Mountain spotted fever  Rickettsia rickettsii  Measles-like rash except that the rash appears on palms and soles too  Vector ▪ Ticks 15

16  Rickettsia are obligate intracellular parasites  Infect and grown in endothelial cells of the vascular system 16

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18  Causative agent: Yersinia pestis, gram-negative rod  Reservoir  Rats, ground squirrels, prairie dogs  Vector  Fleas  Bubonic plague  Bacterial growth in blood and lymph  Septicemia plague  Septic shock  Pneumonic plague  Bacteria in the lungs ▪ Necrotizing hemorrhagic pneumonia  Human to human transmission ▪ Black Death in the middle ages 18

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20  Causative agent: Borrelia burgdorferi  Reservoir: Deer  Vector: Ticks

21  Acute: Bull's-eye rash, fever, muscular and joint pain, meningeal irritation  Chronic : Disabling arthritis, myocarditis, meiningoencephalitis

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23 23  Yellow fever  Liver cells are primary target  Dengue fever  4 serotypes  Infection with a second serotype can lead to severe manifestation  Ebola virus  High mortality rate of 60 – 80% within a few days

24  Caused by Plasmodium species:  P. vivax  P. ovale  P. malariae  P. falciparum  Vector: Anopheles mosquito  Definitive host: Anopheles mosquito

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28  American trypanosomiasis  Causative agent Trypanosoma cruzi  Reservoir: Rodents, opossums, armadillos  Transmitted via feces of kissing bug  Infects organs, chronic infection, organ megaly

29  Endemic in Mexico, Central America, and South America  ~ 8 to 11 million people are infected  Local lesion (chagoma, palpebral edema) at the site of inoculation  Acute phase (2 -3 months)  Usually asymptomatic  If symptomatic: ▪ Fever, anorexia ▪ Lymphadenopathy ▪ Mild hepatosplenomegaly ▪ Myocarditis  Asymptomatic chronic stage (years- decades)  Symptomatic chronic stage  Cardiomyopathy (the most serious manifestation)  Megaesophagus  Megacolon  Weight loss  Can be fatal

30  Infection of venous system by the trematode Schistosoma  Complex life cycle  Pathology mainly due to eggs that protrude into body cavities 30 Eggs Miracidia Sporocysts Cercariae Adults Snail Human

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32  Tissue damage (granulomas) in response to eggs lodging in tissues

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34 34  Cardiovascular and lymphatic systems are in continuous comminucation  Bacterial diseases: Sepsis and septic shock, infections of the heart: endocarditis; rheumatic fever- an autoimmune disease after streptococcal infection; undulating fever caused by brucellosis; systemic diseases caused by bites and scratches: cat scratch disease and Pasteurella infection; vector transmitted diseases: plague, Lyme disease, Rocky Mountain spotted fever, typhus  Viral diseases  Hemorrhagic fevers: Yellow fever, Dengue fever, Ebola hemorrhagic fever (60 – 80% mortality)  Protozoan diseases: Malaria caused by Plasmodium and infects erythrocytes; Chagas disease caused by Trypanosoma cruzi leading to organ infection and organ megaly  Helminthic diseases: Schistosomiasis : adult couple lives in venous system,, pathology due to eggs that penetrate into urinary bladder or intestine.

35 35 1) Which of the following statements about severe sepsis is false? A) Symptoms include fever and decreased blood pressure. B) Lymphangitis may occur. C) Symptoms are due to bacterial endotoxin. D) It usually is caused by gram-positive bacteria. E) It may be aggravated by antibiotics. 2) Which of the following is NOT caused by a bacterium? A) Epidemic typhus B) Tickborne typhus C) Malaria D) Plague E) Relapsing fever 3) Human-to-human transmission of plague is usually by A) Rat flea. B) Dog flea. C) The respiratory route. D) Wounds. E) Unsanitary conditions.


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