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MICR 201 Microbiology for Health Related Sciences

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1 MICR 201 Microbiology for Health Related Sciences
Lecture 15: Microbial diseases of the cardiovascular and lymphatic system Edith Porter, M.D. MICR 201 Microbiology for Health Related Sciences

2 Lecture outline 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 The Cardiovascular and lymphatic system (1)
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

4 The Cardiovascular and lymphatic system (2)

5 Sepsis and septic shock
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

6 Lymphangitis may accompany sepsis
Inflamed lymph vessels accompanying septicemia and septic shock

7 Sepsis Gram-negative sepsis Gram-positive 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

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

9 Bacterial infections of the heart: endocarditis

10 Consequences of endocarditis

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

12 Brucellosis (undulant fever)
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

13 Selected diseases transmitted by scratches and bites
Bartonella henselae: cat-scratch disease Pasteurella multocida: animal bites

14 Animal bites and scratches: Pasteurella multocida
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

15 Rickettsia infections
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

16 Rocky Mountain Spotted Fever
Rickettsia are obligate intracellular parasites Infect and grown in endothelial cells of the vascular system

17 Rocky Mountain Spotted Fever cases 1997 - 2002

18 Plague 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

19 Boubonic plague and US plague cases between 1970 - 2004

20 Lyme Disease Causative agent: Borrelia burgdorferi Reservoir: Deer
Vector: Ticks

21 Clinical stages of Lyme disease
Acute: Bull's-eye rash, fever, muscular and joint pain, meningeal irritation Chronic : Disabling arthritis, myocarditis, meiningoencephalitis

22 Lyme disease in the U.S., 2005

23 Viral hemorrhagic fever
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 Malaria Caused by Plasmodium species: Vector: Anopheles mosquito
P. vivax P. ovale P. malariae P. falciparum Vector: Anopheles mosquito Definitive host: Anopheles mosquito

25 Malaria

26 Malaria in the United States

27 Malaria

28 Chagas’ Disease (1) American trypanosomiasis
Causative agent Trypanosoma cruzi Reservoir: Rodents, opossums, armadillos Transmitted via feces of kissing bug Infects organs, chronic infection, organ megaly

29 Chagas ‘Disease (2) 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 Schistosomiasis Infection of venous system by the trematode Schistosoma Complex life cycle Pathology mainly due to eggs that protrude into body cavities Eggs Miracidia Sporocysts Cercariae Adults Snail Human

31 Life cycle of Schistosoma

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

33 Types of Schistosomiasis
Species Adults Excretion of eggs Affected regions S. haematobium Venous plexus of urinary bladder Urine (bladder cancer) Africa, Middle East S. japonicum Mesenteric veins Feces East Asia S. mansoni African, Middle East, South American, Caribbean

34 Important to Remember 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 Check your understanding
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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