Transcript 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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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
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Viral diseases
 Hemorrhagic fevers
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Protozoan diseases
 Malaria, Chagas disease
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Helminthic diseases
 Schistosomiasis
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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
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Septicemia
 Presence of bacteria in blood with severe
symptoms
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Sepsis
 Bacteria present (and proliferating) in blood and
dissemination into various with organ dysfunction
 Induces a systemic inflammatory response
syndrome
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Severe sepsis
 Sepsis + decreased blood pressure
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Septic shock
 Sepsis + low blood pressure cannot be controlled
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Lymphangitis
 Inflamed lymph vessels accompanying septicemia
and septic shock
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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
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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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Endocarditis
 Inflammation of the endocardium
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Subacute bacterial endocarditis
 Alpha-hemolytic streptococci from mouth
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Acute bacterial endocarditis
 Staphylococcus aureus from mouth
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Pericarditis
 Streptococci
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Inflammation of heart valves and joints
Autoimmune complication of Streptococcus pyogenes
infections
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Brucella, gram-negative rods that grow in
phagocytes
 Granulomas form
 If bacteria are not controlled they can reenter the
bloodstream andcause recurrent
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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
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Bartonella henselae: cat-scratch disease
Pasteurella multocida: animal bites
http://www.lib.uiowa.edu/hardin
/md/pictures22/dermnet/cat_scr
atch_disease_8.jpg
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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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Epidemic typhus
 Rickettsia prowazekii
Rocky Mountain
spotted fever
 Reservoir
 Rickettsia rickettsii
▪ Rodents
 Vector
▪ Lice (Pediculus humanus
corporis)
 Transmitted when louse
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 Measles-like rash except
that the rash appears on
palms and soles too
 Vector
▪ Ticks
feces is rubbed into bite
wound
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 Rickettsia are obligate intracellular parasites
 Infect and grown in endothelial cells of the vascular
system
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Causative agent: Yersinia pestis, gram-negative rod
Reservoir
 Rats, ground squirrels, prairie dogs
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Vector
 Fleas
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Bubonic plague
 Bacterial growth in blood and lymph
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Septicemia plague
 Septic shock
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Pneumonic plague
 Bacteria in the lungs
▪ Necrotizing hemorrhagic pneumonia
 Human to human transmission
▪ Black Death in the middle ages
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Causative agent: Borrelia burgdorferi
Reservoir: Deer
Vector: Ticks
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Acute: Bull's-eye rash, fever, muscular and joint pain,
meningeal irritation
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Chronic : Disabling arthritis, myocarditis,
meiningoencephalitis
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Yellow fever
 Liver cells are primary target
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Dengue fever
 4 serotypes
 Infection with a second
serotype can lead to severe
manifestation
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Ebola virus
 High mortality rate of 60 –
80% within a few days
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Caused by Plasmodium species:
 P. vivax
 P. ovale
 P. malariae
 P. falciparum
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Vector: Anopheles mosquito
Definitive host: Anopheles mosquito
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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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Endemic in Mexico, Central America, and South America
 ~ 8 to 11 million people are infected
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Local lesion (chagoma, palpebral edema) at the site of inoculation
Acute phase (2 -3 months)
 Usually asymptomatic
 If symptomatic:
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Fever, anorexia
Lymphadenopathy
Mild hepatosplenomegaly
Myocarditis
Asymptomatic chronic stage (years- decades)
Symptomatic chronic stage
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Cardiomyopathy (the most serious manifestation)
Megaesophagus
Megacolon
Weight loss
Can be fatal
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Infection of venous
system by the
trematode
Schistosoma
Complex life cycle
Pathology mainly
due to eggs that
protrude into body
cavities
Cercariae
Sporocysts
Adults
Miracidia
Eggs
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Tissue damage (granulomas) in response to
eggs lodging in tissues
Species
Adults
S. haematobium Venous
plexus of
urinary
bladder
Mesenteric
S. japonicum
veins
S. mansoni
Mesenteric
veins
Excretion of
eggs
Affected
regions
Urine
Africa, Middle
(bladder cancer) East
Feces
East Asia
Feces
African, Middle
East, South
American,
Caribbean
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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
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Viral diseases
 Hemorrhagic fevers: Yellow fever, Dengue fever, Ebola hemorrhagic fever (60
– 80% mortality)
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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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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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