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.