Chapter 23
THE CARDIOVASCULAR AND LYMPHATIC
SYSTEMS


The cardiovascular
system: The heart, blood and
blood vessels
The lymphatic system: The
lymph, lymph vessels, lymph
nodes and the lymphoid
organs
Function:
- Distribution of nutrients and
oxygen to body tissues and
carry away waste products

- Defense mechanism
BACTERIAL DISEASES OF THE
CARDIOVASCULAR AND
LYMPHATIC SYSTEMS
SEPSIS AND SEPTIC SHOCK
Gram
negative
sepsis
Gram
positive
sepsis
Puerperal
sepsis
SEPSIS AND SEPTIC SHOCK
Questions:
 Is blood sterile?
 Can a microorganism enter blood without causing
harm?
 How?
 When can the microorganism cause a disease?
Answers:
 Yes
 Yes, if moderate numbers
 In hospital conditions as invasive procedures, such as
insertion of catheters and IV feeding tubes
 If defense mechanisms fail and microbes can
proliferate in blood
SEPSIS AND SEPTIC SHOCK – CONT’D

Septicemia: persistence of pathogenic organisms and
their toxins in blood
Sepsis: systemic inflammatory response syndrome
(SIRS)
- At least two of a set of defined conditions: fever, rapid
heart or respiratory rates, and a high count of WBCs


Lymphangitis inflamed lymph vessels visible as red
streaks under the skin
Lymphangitis
SEPSIS AND SEPTIC SHOCK – CONT’D


Sever sepsis: a drop in blood pressure and
dysfunction of at least one organ
Septic shock: the final stage, low blood pressure
can no longer be controlled by addition of fluids
GRAM NEGATIVE SEPSIS


Septic shock is most likely to be caused by Gram
negative bacteria (Why?)
Septic shock is called endotoxic shock (Why?)
Treatment:
- Is antibiotic use of value?

GRAM POSITIVE SEPSIS

Gram positive bacteria are the most common cause of
sepsis in hospitals…why?

Predisposing factors?

Virulence factors ?
Staphylococus aureus and Streptococcus pyogenes
:TSS
 Enterococcus spp: :infections of wounds, UTI and others
 Group B streptococcus (S.agalactiae), the most
common cause of life threatening neonatal sepsis
- CDC, recommends that pregnant women be tested for
vaginal GBS….Why?
 Treatment: vancomycin

PUERPERAL SEPSIS

Puerperal fever or childbirth fever: Infection
of the uterus as a result of childbirth or abortion
Causative bacteria: GAS
 Local infection of the uterus----- peritonitis and
sepsis
 Mode of transmission?

Treatment:
- Penicillin
- Modern hygienic practices

BACTERIAL INFECTIONS OF THE HEART
“ENDOCARDITIS”






The heart: endocardium, myocardium and
pericardium
Endocardium: it is the inner layer lines the heart muscles
and covers the valves
Endocarditis?
Subacute bacterial endocarditis:
It develops slowly over a period of weeks or months
Characterized by: fever, general weakness and heart
murmur

Causative bacteria: Streptococcus viridans (oral
streptococci). E.g. S.mutans and S.sangius

Predisposing factors?
BACTERIAL INFECTIONS OF THE HEART
“ENDOCARDITIS”-CONT’D

Pathogenesis:
After tooth extraction bacteria enter the blood, and find their way
to the heart

The body’s defense mechanisms?

Abnormal heart valves, the bacteria lodge in the preexisting lesion

The bacteria multiply and become entrapped in blood clots that
protect them from phagocytes and antibodies

Pieces of the clot break off and can block blood vessels or lodge in the
kidneys

The function of the heart valve is impaired

SBE is fatal within few months

Subacute – Bacterial
Endocarditis
ACUTE BACTERIAL
ENDOCARDITIS
Causative organism: Staph.aureus
- From the initial site of infection to normal or
abnormal heart valves
- Fatal within a few days or weeks if untreated


Pericarditis: inflammation of the sac around
the heart (pericardium). Streptococcus pyogenes
can cause it (GAS)
RHEUMATIC FEVER

Causative organism: Streptococcus pyogenes (GAS)
Post streptococcal squeal in 4-18 years, following
streptococcal sore throat

Complain: short periods of arthritis and fever, then
subcutaneous nodules at joints accompany this stage

Pathogenesis: misdirected immune reaction against
streptococcal M protein, damages the heart valves??
- Reinfection with streptococci renews the immune
attack
- Damage of the heart valves may be serious enough to
result in eventual failure and death


Treatment: long acting penicillin (monthly injection)
THEORIES OF OCCURRENCE OF RHEUMATIC
FEVER

Direct toxicity:?

Antigenic cross reactivity:?
A nodule causes by
rheumatic fever
BRUCELLOSIS (UNDULANT FEVER)


Causative bacteria: Brucella, small aerobic gram
negative coccoid bacilli
zoonosis?

Brucella abortus: in cattle and camels
Brucella suis: in swine, and can infect cattle when kept in
contact with swine
Brucella meletensis: in goats and sheep

Virulence factor??


Mode of transmission:
- Occupational disease: farmers, shepherds, butchers and
veterinaries.
- Oral route, skin abrasions, droplet infection through mucous
membranes
- Person to person transmission is very rare.

BRUCELLOSIS (UNDULANT FEVER)-CONT’D
IP: 1-3 weeks or longer
 Symptoms:
- Fever (often rising and falling= undulant fever),
malaise, night sweats and muscle aches
- Physical examination: splenomegaly may be the only
finding
 Complications: arthritis and meningitis
 Diagnosis:
- Serological tests
- Isolation of organism from blood or tissues
- It needs incubation for a long period…Why?
 Treatment: combination of at least 2 antibiotics as
tetracycline and streptomycin for at least 6 weeks
 Control??

GANGRENE – CLOSTRIDIAL MYONECROSIS
Causative bacteria: Clostridium perfringenes
- It is widely found in ………..

Virulence factors:
-Toxin: lecithinase.
-Enzymes (spreading factors??)

Pathogenesis:
- Trauma (wound) will lead to interrupted blood supply
(ISCHEMIA) and the wound becomes anaerobic
- Ischemia leads to necrosis (death of the tissues)
- The death of soft tissue results from the loss of blood
supply is called gas gangrene, especially in muscle
tissues (myonecrosis)

Trauma
Ischemia
Necrosis
Anaerobic
GANGRENE – CONT’D
Pathogenesis “ continue”:
- Cl.perfringenes ferment carbohydrates in the tissues
and produce gasses (carbon dioxide and hydrogen)
that swell the tissues
- The bacteria produce toxins that move along muscle
bundles, killing cells and produce necrotic tissues
- The toxins and bacteria then enter the blood stream
- Production of enzymes degrade collagen leading to
spread of the disease

Symptoms:
- IP 1-3 days after injury, pain in the affected area,
crepitation of SC tissues, foul smelling
- Skin color changes and finally becomes black
- Death occurs rapidly in untreated cases

GANGRENE – CONT’D
- Treatment:
- Surgical
- Hyperbaric chamber
-High dose of Penicillin or clindamycin or
metronidazole
The toes of a patient
with gangrene
REVIEW QUESTIONS
True or false:
 Septicemia refers to the presence of bacteria in
blood
 Gram positive sepsis can lead to endotoxic shock
 Endotoxic shock occurs due to the presence of
teichoic acid in bacterial cell wall
 Antibiotic intake causes immediate improvement
of a patient with endotoxic shock
 It is recommended to test pregnant females for
vaginal colonization with Staph.aureus
 The commonest organism causing puerperal
sepsis is Strept.viridans