Transcript Lecture 23

Chapter 23, Chapter 24
Microbial Diseases of the Cardiovascular and
Lymphatic Systems
Microbial Diseases of the Respiratory System
The Cardiovascular System
• Blood is a mixture of plasma and cells
• Red blood cells carry oxygen
• White blood cells are involved in the body’s defense against
infection.
Figure 23.1
The Lymphatic System
• Fluid that filters out of capillaries into spaces between tissue
cells is called interstitial fluid.
• Interstitial fluid enters lymph capillaries and is called lymph;
• Vessels called lymphatic return lymph to the blood.
Figure 23.2
Sepsis and Septic Shock
• Sepsis is an inflammatory response caused by the spread of
bacteria or their toxin from a focus of infection.
• Septicemia is sepsis that involves proliferation of pathogens in
the blood.
• Septic shock- low blood pressure which cannot be controlled
• Lymphangitis -inflammation of the lymphatic channels that occurs
as a result of infection at a site distal to the channel.
– The most common cause of Lymphangitis
in humans is Streptococcus Pyogenes
Lymphangitis
Figure 23.3
Sepsis
1. Gram-Positive Sepsis
– Exotoxins, Nosocomial infections,
• Staphylococcus aureus
• Streptococcus pyogenes
• Group B streptococcus
• Enterococcus faecium and E. faecalis
2. Gram-negative sepsis
– Endotoxins caused blood pressure decrease and septic shock .
– Antibiotics can worsen condition by killing bacteria
3. Puerperal Sepsis (Childbirth fever)
– Streptococcus pyogenes
– Puerperal sepsis begins as an infection of the uterus following childbirth or
abortion; it can progress to peritonitis or septicemia.
– Puerperal sepsis was transmitted by the hands and instruments of midwives
and physicians.
– Puerperal sepsis is now uncommon because of modern hygienic techniques
and antibiotics
Bacterial Infections of the Heart
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Endocarditis
• The inner layer of the heart is the endocardium.
• Inflammation of the endocardium
– Subacute bacterial endocarditis –
• from microbes in the mouth.( Arises from a focus of infection, such as
a tooth extraction).
– Alpha-hemolytic streptococci
– Staphylococci
– Enterococci
• Preexisting heart abnormalities are predisposing factors.
• Signs include fever, anemia, and heart murmur.
– Acute bacterial endocarditis
• Staphylococcus aureus
• The bacteria cause rapid destruction of heart valves
Rheumatic Fever
• Rheumatic fever is an inflammatory disease that may develop after
an infection with Streptococcus bacteria (such as strep throat or
scarlet fever).
– The disease can affect the heart, joints, skin, and brain
• Symptoms
– Abdominal pain
– Fever
– Heart (cardiac) problems, which may not have symptoms,
or may result in shortness of breath and chest pain
– Joint pain, arthritis (mainly in the knees, elbows, ankles, and wrists)
– Joint swelling; redness or warmth
– Nosebleeds
– Skin nodules
• Streptococci might not be present at the time of rheumatic fever.
• Prompt treatment of streptococcal infections can reduce the
incidence of rheumatic fever (Penicillin is administered as a
preventive measure against subsequent streptococcal infections.)
Zoonotic disease
• Tularemia– Francisella tularensis, gram-negative rod
– Bacteria reproduce in phagocytes
– Transmitted from rabbits and deer by deer flies
• Brucellosis (Undulant Fever)
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Brucella, gram-negative rods that grow in phagocytes,
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
Anthrax
• Bacillus anthracis,
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Gram-positive,
Endospore-forming aerobic rod
Found in soil
Multiply in macrophages and produce two exotoxins
• Edema toxin
• Lethal toxin
• These toxins are the primary agents of tissue destruction, bleeding, and death of the host.
• Cutaneous anthrax
– Endospores enter through minor cut
– 20% mortality
• Gastrointestinal anthrax
– Ingestion of undercooked contaminated food
– 50% mortality
• Inhalational anthrax
– Inhalation of endospores
– 100% mortality
• Cattle are routinely vaccinated
• Treated with ciprofloxacin or doxycycline
Portal of entry
ID50
Skin
10-50
endospores
Inhalation
10,000-20,000
endospores
Ingestion
250,0001,000,000
endospores
Gas Gangrene
• Ischemia ( Loss of blood supply to tissue)
– Necrosis (Death of tissue)
• Gangrene (Death of soft tissue)
• Gas gangrene
– Clostridium perfringens,
– gram-positive,
– anaerobic rod,
– endospore-forming
– grows in necrotic tissue
• Treatment includes surgical removal of necrotic tissue and/or hyperbaric
chamber
Vector transmitted disease - Plague
• Plague - enterobacteria Yersinia
pestis
• gram-negative rod
• grow in blood and lymph
• plague bacteria secrete several
toxins
• Transmitted by rat flea
– Septicemia plague - Septic shock
– Pneumonic plague - Bacteria in the
lungs
• Treatments - antibiotics
Vector transmitted disease - Lyme Disease
• Borrelia burgdorferi
• Reservoir - Deer
• Vector - Ticks
• First symptoms
– may include fever, headache, fatigue, depression
– a characteristic circular skin rash called erythema migrans (bull's eye rash)
– eliminated by antibiotics, especially if the illness is treated early
• Second phase
– Irregular heartbeat
– Encephalitis
• Third phase
– Arthritis (Borrelia causes autoimmunity)
Figure 23.14
Figure 23.14
Vector transmitted disease - Rickettsias
• Epidemic typhus
– Rickettsia prowazekii
• gram negative, bacillus, obligate intracellular parasitic, aerobic bacteria
• transmited by human body louse Pediculus humanus corporis
– causes tickborne typhus fever
– prevalent in crowded and unsanitary living conditions that allow the
proliferation of lice
– signs of typhus - rash, prolonged high fever, and stupor
– Treatment - tetracycline and chloramphenicol
• Endemic murine typhus
– a less severe disease caused by Rickettsia typhi and transmitted from
rodents to humans by the rat flea.
• Spotted Fevers (Rocky Mountain spotted fever)
– Rickettsia rickettsii is a parasite of ticks (Dermacentor spp.) in the
southeastern United States, Appalachia, and the Rocky Mountain states
– chloramphenicol and tetracycline effectively treat Rocky Mountain spotted
fever, or tick-borne typhus.
• Serological tests are used for laboratory diagnosis.
Viral Diseases of the Cardiovascular and Lymphatic Systems
• Infectious Mononucleosis
• Mononucleosis is caused by Epstein-Barr virus.
• Human herpes virus 4
• The virus multiplies in the parotid glands and is present in saliva.
• It causes the proliferation of atypical lymphocytes.
• The disease is transmitted by the ingestion of saliva from infected
individuals.
• Childhood infections are asymptomatic
• Diagnosis is made by an indirect fluorescent-antibody
technique.
• EB virus may cause other diseases,
including cancers and multiple sclerosis.
Viral Diseases of the Cardiovascular and Lymphatic Systems
• Burkitt lymphoma is a cancer of the lymphatic system (in
particular, B lymphocytes).
• It is named after Denis Burkitt, a surgeon who first described the
disease in 1956 while working in equatorial Africa.
• Epstein-Barr virus (Human herpes virus 4)
– The endemic variant occurs in equatorial Africa. It is the most common
malignancy of children in this area.
– Children affected with the disease often also had chronic malaria
– Disease characteristically involves the jaw or other facial bone, distal ileum,
cecum, ovaries, kidney or the breast.
– The sporadic type of Burkitt lymphoma (also known as "non-African") is
another form found outside of Africa.
– It is believed that impaired immunity provides an opening for development of the
Epstein-Barr virus.
– Immunodeficiency-associated Burkitt lymphoma is usually associated
with HIV infection or occurs in the setting of post-transplant patients who
are taking immunosuppressive drugs.
Viral Diseases of the Cardiovascular and Lymphatic
Systems
• Cytomegalic Inclusion Disease
– Cytomegalovirus (Human herpes virus 5)
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Infected cells swell (cyto-, mega-)
Latent in white blood cells
Cause formation of distinctive inclusion bodies
May be asymptomatic or mild.
Transmitted across the placenta, may cause mental retardation,
sexually, by blood, by transplanted tissue
– Viral hemorrhagic fevers are caused by viruses from four
distinct families.
•
Range in severity from relatively mild to life-threatening.
• Begin with fever and muscle aches.
• Some viral hemorrhagic fevers progress to far more serious problems,
including severe internal and external bleeding (hemorrhage),
widespread tissue death (necrosis), and shock.
• No current treatment can cure viral hemorrhagic fevers, and
immunizations exist for only two of the many VHFs
Protozoan Diseases of the Cardiovascular and Lymphatic Systems
• Chagas’Disease - Trypanosoma cruzi
– Reservoir-Rodents, opossums,
armadillos
– Vector- Reduviid bug
• Leishmaniasis -Leishmania spp.
– Vector- Sandflies. The protozoa
reproduce in the liver, spleen, and
kidneys.
– Antimony compounds are used for
treatment.
• Babesiosis - Babesia microti
• transmitted to humans by ticks.
Figure 23.22, 12.33d
Toxoplasmosis
• Toxoplasmosis is caused by Toxoplasma gondii.
– T. gondii undergoes sexual reproduction in the intestinal tract of domestic
cats, and oocysts are eliminated in cat feces.
– In the host cell, sporozoites reproduce to form either tissue-invading
tachyzoites or bradyzoites.
• Humans contract the infection by ingesting tachyzoites or tissue
cysts in undercooked meat from an infected animal or contact with
cat feces.
• Congenital infections can occur. Signs and symptoms include
severe brain damage or vision problems.
• Toxoplasmosis can be identified by serological tests, but
interpretation of the results is uncertain.
Malaria
• Malaria is transmitted by Anopheles mosquitoes. The causative
agent is any one of four species of Plasmodium.
• The signs and symptoms occur at intervals of 2 to 3 days.
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chills,
fever,
vomiting,
headache, which
Sporozoites reproduce in the liver and release merozoites into the
bloodstream, where they infect red blood cells and produce more
merozoites.
• New drugs are being developed as the protozoa develop resistance
to drugs such as chloroquine.
Learning objectives
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Identify the role of the cardiovascular and lymphatic systems in spreading and
eliminating infections.
List the signs and symptoms of septicemia, and explain the importance of infections that
develop into septicemia.
Differentiate gram-negative sepsis, gram-positive sepsis, and puerperal sepsis.
Describe the epidemiologies of bacterial endocarditis and rheumatic fever.
Discuss the epidemiology of tularemia. Brucellosis and antrax.
Discuss the epidemiology of gas gangrene.
List three pathogens that are transmitted by animal bites and scratches.
Compare and contrast the causative agents, vectors, reservoirs, symptoms, treatments,
and preventive measures for plague, Lyme disease, and Rocky Mountain Spotted Fever.
Identify the vector, etiology, and symptoms of five diseases transmitted by ticks.
Describe the epidemiologies of epidemic typhus, endemic murine typhus, and spotted
fevers.
Describe the epidemiologist of CMV inclusion disease, Burkitt’s lymphoma, and
infectious mononucleosis.
Compare and contrast the causative agents, modes of transmission and reservoirs, for
toxoplasmosis, malaria, leishmaniasis, and babesiosis.
Structure and Function of the Respiratory System
• The upper respiratory system consists of :
– Nose
– Pharynx
– Sinus
– Middle ear and auditory tubes.
• Coarse hairs in the nose filter large particles from air entering the
respiratory tract.
• The ciliated mucous membranes of the nose and throat trap
airborne particles and remove them from the body.
• Lymphoid tissue, tonsils, and adenoids provide immunity to
certain infections.
Microbial Diseases of the Upper Respiratory System
• Upper respiratory normal microbiota may include pathogens
• Laryngitis:
• S. pneumoniae,
• S. pyogenes,
• viruses
• Tonsillitis:
• S. pneumoniae,
• S. pyogenes,
• viruses
• Sinusitis:
• Bacteria
• Epiglottitis:
• H. influenzae
Streptococcal pharyngitis
• Strep throat
– Streptococcus pyogenes
– Resistant to phagocytosis
– Streptokinases lyse clots
– Streptolysins are cytotoxic
• Scarlet Fever ( scarlatina )
– Erythrogenic toxin produced
by lysogenized S. pyogenes
• Diagnosis by indirect agglutination
Figure 24.3
Diphtheria
• Corynebacterium diphtheriae.
• exotoxin-producing
• Diphtheria
– A membrane, containing fibrin and dead human
and bacterial cells, forms in the throat and can
block the passage of air.
– The exotoxin inhibits protein synthesis,
– Heart, kidney, or nerve damage may result.
• Laboratory diagnosis is based on isolation of the bacteria and the appearance
of growth on differential media.
• Antitoxin must be administered to neutralize the toxin, and antibiotics can stop
growth of the bacteria.
• Routine immunization in the United States includes diphtheria toxoid in the
DTaP vaccine.
• Slow-healing skin ulcerations are characteristic of cutaneous diphtheria.
Common cold
• Rhinoviruses (50%)
• Coronaviruses (15-20%)
• Rhinoviruses attached to ICAN-1 on nasal
mucous
Infection of he middle ear
• Otitis Media
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S. pneumoniae (35%)
H. influenzae (20-30%)
M. catarrhalis (10-15%)
S. pyogenes (8-10%)
S. aureus (1-2%)
• Treated with broad-spectrum antibiotics
• Incidence of S. pneumoniae reduced by vaccine
Structure and Function of the Respiratory System
• The lower respiratory system consists of:
– Trachea
– Bronchial tubes
– Alveoli.
Figure 24.2 – Overview (1 of 3)
• The ciliary escalator of the lower respiratory system helps
prevent microorganisms from reaching the lungs.
• Microbes in the lungs can be phagocytized by alveolar
macrophages.
• Respiratory mucus contains IgA antibodies.
Pertussis (Whooping Cough)
• Bordetella pertussis:
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Gram-negative coccobacillus
Capsule
Tracheal cytotoxin of cell wall damaged ciliated cells
Pertussis toxin - inhibit the function of the host's immune system
• Stages
– Catarrhal stage, like common cold
– Paroxysmal stage: Violent coughing siege
– Convalescence stage
• Prevented by DTaP vaccine (acellular Pertussis cell
fragments)
Figure 24.8
Microbial Diseases of the Lower Respiratory
System
• Bacteria, viruses, & fungi cause:
– Bronchitis
- inflammation of the bronchi.
• Symptoms include: Coughing up extra mucus, sometimes with blood,
Wheezing, Difficulty breathing, Runny nose
– Bronchiolitis - inflammation of the bronchioles, the smallest air passages
of the lungs.
– Pneumonia -inflammatory illness of the lung. Frequently, it is described
as lung parenchyma/alveolar inflammation and abnormal alveolar filling
with fluid.
• The alveoli are microscopic air-filled sacs in the lungs responsible for
absorbing oxygen.
• Typical symptoms associated with pneumonia include cough, chest pain,
fever, and difficulty in breathing
Tuberculosis
• Mycobacterium tuberculosis:
– Acid-fast rod.
– Transmitted from human to human
• M. bovis
– <1% U.S. cases,
– Not transmitted from human to human
• M. avium
– Intracellular complex
– Infects people with late stage HIV infection
• Symptoms: a chronic cough with blood-tinged sputum, fever, night
sweats, and weight loss.
– Infection of other organs causes a wide range of symptoms.
• Treatment of Tuberculosis: Prolonged treatment with multiple
antibiotics
• Vaccines: BCG, live, avirulent M. bovis. Not widely used in U.S.
Figure 24.9
The Pathogenesis of Tuberculosis
Tuberculosis
Diagnosis: Tuberculin skin test screening
Tuberculin skin test screening
Positive reaction means current or previous infection
Followed by X-ray or CT exam, acid-fast staining of sputum,
culturing of bacteria
Figure 24.11
Pneumonias
• Pneumonia
– An illness of the lungs and in which the alveoli (microscopic air-filled sacs
of the lung responsible for absorbing oxygen) become inflamed and flooded
with fluid.
• Pneumonia can result from a variety of causes – bacteria, viruses,
fungi or parasites
– Typical pneumonia is caused by S. pneumoniae.
– Atypical pneumonias are caused by other microorganisms.
• Typical symptoms
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cough,
chest pain,
fiver,
breathing difficulty,
rust-colored sputum.
• Diagnostic tools include x-rays and examination of the sputum.
• Treatment depends on the cause of pneumonia; bacterial
pneumonia is treated with antibiotics.
Pneumomoccal Pneumonia
• Streptococcus pneumoniae:
• Gram-positive encapsulated diplococci
• Diagnosis by culturing bacteria
• Penicillin is drug of choice
Figure 24.13
Pneumonia
• Haemophilus influenzae
– Gram-negative coccobacillus
– Alcoholism, poor nutrition, cancer, or diabetes are predisposing factors
– Second-generation cephalosporins
• Mycoplasma pneumoniae
– It is an endemic disease.
– Diagnosis is by PCR or serological tests.
• Legionella pneumophila
– Aerobic gram-negative rod.
– The bacterium can grow in water
• such as air-conditioning cooling towers,
• and then be disseminated in the air.
– This pneumonia does not appear to be transmitted from person to person.
– Bacterial culture, FA tests, and DNA probes are used for laboratory
diagnosis.
Obligate intracellular pathogens
• Chlamydophila pneumoniae
– Has a complex life cycle and must infect another cell in order to reproduce.
– It is transmitted from person to person.
– Tetracycline is used for treatment.
• Coxiella burnetii causes Q fever.
– The disease is usually transmitted to humans through unpasteurized milk or
inhalation of aerosols in dairy barns.
– Laboratory diagnosis is made with the culture of bacteria in embryonated
eggs or cell culture.
Viral Pneumonia
• Viral pneumonia as a complication of influenza, measles,
chickenpox
• Viral etiology suspected if no cause determined
• Respiratory Syncytial Virus (RSV)
– Common in infants; 4500 deaths annually
– Causes cell fusion (syncytium) in cell culture
– Symptoms: coughing
– Diagnosis by serologic test for viruses and antibodies
– Treatment: Ribavirin
Influenza -Influenza virus
• Family: Orthomyxaviradae (ssRNA)
– Hemagglutinin (H) spikes - used for attachment to host cells
– Neuraminidase (N) spikes - used to release virus from cell
– Antigenic shift
• Changes in H and N spikes - probably due to genetic recombination between
different strains infecting the same cell
– Antigenic drift
• Mutations in genes encoding H or N spikes (may involve only 1 amino acid)
• Allows virus to avoid mucosal IgA antibodies
– Influenza serotypes
• A: causes most epidemics, H3N2, H1N1, H2N2
• B: moderate, local outbreaks
• C: mild disease
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Chills, fever, headache, muscle aches (no intestinal symptoms), 1% mortality due to
secondary bacterial infections
Treatment: Amantadine (interference with a viral protein, M2,which is required for the viral
particle to become "uncoated" once taken inside a cell by endocytosis)
Vaccine for high-risk individuals
Fungal Diseases of the Lower Respiratory System
• Fungal spores are easily inhaled;
– They may germinate in the lower respiratory tract.
• The incidence of fungal diseases has been increasing in recent
years.
• The mycoses in the sections below can be treated with
amphotericin B.
Fungal Diseases of the Lower Respiratory System
• Histoplasmosis
– Histoplasma capsulatum
– subclinical respiratory infection that only occasionally progresses to a
severe, generalized disease.
• Coccidioidomycosis
– Coccidioides immitis – Most cases are subclinical,
– tuberculosis can result.
• Pneumocystis Pneumonia
– Pneumocystis jiroveci is found in healthy human lungs,
– causes disease in immunosuppressed patients.
• Opportunistic fungi can cause respiratory disease in
immunosuppressed hosts, especially when large numbers of spores
are inhaled - Aspergillus, Rhizopus, and Mucor.
Learning objectives
• Describe how microorganisms are prevented from entering the respiratory
system.
• Characterize the normal microbiota of the upper and lower respiratory systems.
• Differentiate among pharyngitis, laryngitis, tonsillitis, sinusitis, and epiglottitis.
• List the causative agent, symptoms, prevention, preferred treatment, and
laboratory identification tests for streptococcal pharyngitis, scarlet fever,
diphtheria, cutaneous diphtheria, and otitis media.
• List the causative agents and treatments for the common cold.
• List the causative agent, symptoms, prevention, preferred treatment, and
laboratory identification tests for pertussis and tuberculosis.
• Compare and contrast the seven bacterial pneumonias discussed in this chapter.
• List the causative agent, symptoms, prevention, and preferred treatment for viral
pneumonia, RSV, and influenza.
• List the causative agent, mode of transmission, preferred treatment, and
laboratory identification tests for four fungal diseases of the respiratory system.