1. Blood and Lymphatic Infections
Chapter 28

3. A Diagram of the Circulatory System

4. Subacute Bacterial Endocarditis

5. Gram-Negative Septicemia
Causative agent
Gram (-) bacteria more likely cause of fatal septicemia
Shock is common despite treatment
Mortality rate nearly 50% due to shock and lung damage
Blood cultures from patients usually reveal
E. coli
Ps. Aeruginosa
Bacteroides sp.
Symptoms
Violent shaking chills and fever
Often accompanied by anxiety and rapid breathing
In case of septic shock
Urine output drops
Respiration and pulse become more rapid
Arms and legs become cool and dusky colored

6. Gram-Negative Septicemia
Pathogenesis
Generally originates outside of bloodstream
Endotoxin is released
Antibiotics can enhance endotoxin release
Exaggerated response Macrophage response to endotoxin
Failed localization allows endotoxin into bloodstream
Causes cascade of harmful events
Lungs particularly susceptible to irreversible damage
Often results in death despite successful treatment of infection

7. Gram-Negative Septicemia
Epidemiology
Mainly a nosocomial disease
General trend
increased life span
antibiotic suppression of normal flora
use of immunosuppressive drugs
biofilm formation of medical devices
Prevention and Treatment
Identification and effective treatment of localized infections
Treatment against causative organisms

8. Tularemia (Rabbit Fever)
Causative agent
Francisella tularensis
Non-motile, aerobic, Gram (-) rod
Symptoms
Characterized by development of skin ulcerations and enlargement of regional lymph nodes
Flu-like
Symptoms usually abate in 1 to 4 weeks
Sometimes may become chronic

9. Tularemia (Rabbit Fever)
Pathogenesis: 90% of infected individuals survive in the absence of treatment
Causes ulcer at entry sight
Lymphatic vessels carry organism to regional lymph nodes
Become large, tender and filled with pus
Spread to other body sites via lymphatics and blood vessels
Pneumonia occurs in 10% - 15% of lung infections
Multiplies within phagocytes
Cell mediated immunity responsible for ridding infection

10. Tularemia (Rabbit Fever)
Epidemiology
Occurs among wild animals in Northern Hemisphere
In eastern U.S. most infections occur in winter
Result from skinning hunted rabbits
In western U.S. infections increase in summer
Due to bites from fleas and ticks
Other reservoirs for infection include
Muskrats, beavers, squirrels, and deer
Prevention and Treatment
Uses PPE when working with animal carcasses
Insect repellents and protective clothing, inspect routinely for ticks
Vaccine available for workers at higher risk of exposure
Treated with gentamicin

11. Brucellosis (Undulant Fever)
Causative agent
Four varieties of Brucella melitensis cause disease in humans
Traditionally each variety given own species name depending on preferred host
B. abortus  cattle
B. canis  dogs
B. melitensis  goats
B. suis  pigs
Organism is Gram (-) rod

12. Brucellosis (Undulant Fever)
Symptoms
Onset usually gradual and symptoms vague
Symptoms flu-like
Without treatment most cases recover within 2 months
15% will be symptomatic for 3 months or longer

13. Brucellosis (Undulant Fever)
Pathogenesis
Organism penetrates mucous membranes or break in skin
Disseminated via lymphatic or blood vessels
Generally to heart , kidneys, and spleen
Organisms resistant to phagocytic killing
Mortality generally due to endocarditis
Rate is approximately 2%
Osteomyelitis is another serious side effect

14. Brucellosis (Undulant Fever)
Epidemiology
Chronic infection of domestic food animals
Generally involving the mammary gland and uterus
Occurs in workers in meat packing industry
Prevention and Treatment
Pasteurization
Inspection of domestic animals
PPE when working with animals or animal carcass
Attenuated vaccine controls disease in domestic animals
Tetracycline combined with rifampin for 6 weeks

15. Plague (Black Death) Causative agent Yersinia pestis
Facultative intracellular bacteria
Resemble safety pin in stained preparation

16. Plague (Black Death) Symptoms
Develop abruptly 1 – 6 days post infection
Transmission via bite from infected flea
Disease characterized by large tender lymph nodes called buboes
Other symptoms include
High fever
Shock
Delirium
Patchy bleeding under the skin
May also have cough and bloody sputum
Only in lungs infected
Pneumonic plague

17. Plague (Black Death) Pathogenesis
Flea regurgitates infected material into bite wound
Pla is essential to spread from site of entry
Organisms multiply within macrophages
Macrophages die and release organism
Inflammation in nodes results in characteristic swelling
Nodes become necrotic and spill organisms
Septicemic plague
Mortality rate of untreated reaches between 50% and 80%

18. Plague (Black Death) Epidemiology Prevention and Treatment
Endemic on rodent populations in all continents except Australia
Prairie dogs, rock squirrels and their fleas are main reservoir
Can spread person to person by household fleas
Organism can remain viable for weeks in dried sputum and flea feces
Prevention and Treatment
Prevention directed by rat control
Killed vaccine gives short-term partial protection
Prompt diagnosis and treatment prevent high mortality
tetracycline for some exposed individuals to control epidemics
Gentamicin, ciprofloxacin and doxycycline effective if given early

19. Infectious Mononucleosis
Causative agent
Caused by Epstein-Barr virus
Double-stranded DNA virus
Belongs to herpesvirus family
Symptoms
Appear after long incubation
Usually 30 to 60 days post infection
Symptoms include fever, sore throat covered with pus, fatigue, enlarged lymph nodes and spleen
Most cases fever and sore throat disappear within 2 weeks, lymph node enlargement within 3

20. Pathogenesis of Epstein-Barr Virus

21. Infectious Mononucleosis
Epidemiology
Distributed worldwide
Infects individuals in crowded, economically disadvantaged areas
Infects at early age without producing symptoms producing immunity
More affluent populations missed exposure and lack immunity
Virus present in saliva for up to 18 months
Mouth-to-mouth kissing important mode of transmission
No animal reservoir
Prevention and Treatment
Avoiding saliva of another person

22. Yellow Fever Causative agent Enveloped, single-stranded RNA arbovirus
Belongs to flavivirus family
Virus multiplies in mosquitoes
Mosquitoes transmit virus to humans
Symptoms
Disease can range from mild to severe
Most common form may be only fever and slight headache lasting a day or two
Severe disease characterized by high fever, nausea, nose bleeds and bleeding into the skin, “black vomit” from GI bleeding and jaundice
Mortality rate of severe disease can reach 50%
Reason for the variation in symptoms is unknown

23. Yellow Fever Pathogenesis Introduce via bite of Aedes mosquitoes
Multiplies and enters blood stream
Carried to liver
Jaundice results in liver damage
Injury to small blood vessels produces petechiae
Kidney failure is a common consequence of disease
Epidemiology
Reservoir mainly infected mosquitoes and primates in tropical regions of Central and South America and Africa
Periodically spread to urban areas via mosquito bite
Prevention and Treatment
Control achieved by spraying and elimination of breeding sites

24. Malaria Causative agent
Human malaria caused by four species of genus Plasmodium
P. vivax, P. falciparum,
P. malatiae, P. ovale
Infectious form of parasite injected via mosquito
Carried by bloodstream to liver
Infects cells of liver
Thousands of offspring released to produce infection in erythrocytes

25. Malaria Symptoms “flu-like” Generally begin 2 weeks post infection
Transmission via bite of infected mosquito
Symptom pattern changes after 2 to 3 weeks
Falls into three categories
Cold phase – abruptly feels cold and develops shaking
Hot phase – follows cold phase
Temperature rises steeply reaching 104°F
Wet phase – follows hot phase
Temperature falls and drenching sweat occurs

26. Malaria Pathogenesis Characteristic feature
Recurrent bouts of fever followed by times of wellness
Caused by erythrocytic cycle of growth and release of offspring
Spleen enlarges to cope with large amount of foreign material and abnormal RBC
Parasites cause anemia by destroying red RBC and converting iron from hemoglobin to non-usable form
Stimulates immune system
Overworked immune system fails and immunodeficiency develops

27. Malaria Epidemiology Prevention and Treatment
Once common in both temperate and tropical areas
Now dominantly disease of warm climate
Eliminated from continental U.S. in late 1940’s
Mosquitoes of genus Anopheles are biological vectors
Infected mosquitoes and humans constitute reservoir
Transmission via mosquitoes, blood transfusion and sharing of syringes
Prevention and Treatment
Treatment is complicated
Chloroquine
Primaquine and tafenoquine