MICR 201 Microbiology for Health Related Sciences

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MICR 201 Microbiology for Health Related Sciences

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

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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

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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 capillariesTransport interstitial fluid to
  blood
• Lymph nodesContain macrophages, dendritic cells,
  B cells and T cells

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The Cardiovascular and lymphatic system (2)
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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

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Lymphangitis may accompany sepsis

• Lymphangitis
• Inflamed lymph vessels accompanying septicemia
  and septic shock

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Sepsis

• 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

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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

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Bacterial infections of the heart endocarditis
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Consequences of endocarditis
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Rheumatic Fever

• Inflammation of heart valves and joints
• Autoimmune complication of Streptococcus pyogenes
  infections

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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 40C each evening
• Transmitted via milk from infected animals or
  contact with infected animals

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Selected diseases transmitted by scratches and
bites

• Bartonella henselae cat-scratch disease
• Pasteurella multocida animal bites

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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

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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

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Rocky Mountain Spotted Fever

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

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Rocky Mountain Spotted Fever cases 1997 - 2002
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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

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Boubonic plague and US plague cases between 1970
- 2004
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Lyme Disease

• Causative agent Borrelia burgdorferi
• Reservoir Deer
• Vector Ticks

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Clinical stages of Lyme disease

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

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Lyme disease in the U.S., 2005
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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

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Malaria

• Caused by Plasmodium species
• P. vivax
• P. ovale
• P. malariae
• P. falciparum
• Vector Anopheles mosquito
• Definitive host Anopheles mosquito

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Malaria
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Malaria in the United States
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Malaria
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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

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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

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Schistosomiasis

• Infection of venous system by the trematode
  Schistosoma
• Complex life cycle
• Pathology mainly due to eggs that protrude into
  body cavities

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Life cycle of Schistosoma
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Schistosomiasis

• Tissue damage (granulomas) in response to eggs
  lodging in tissues

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Types of Schistosomiasis
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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.

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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.