Bacterial Infection of The Blood

‫‪Bacterial Infection of‬‬
‫‪The Blood‬‬
‫إعداد الطلبة ‪:‬‬
‫عبداهلل نبيل حميد‬
‫طـ ــه وليــد عثم ــان‬
Bacterial Infection of
The Blood
Bacteraemia
Pyaemia
Septicaemia
Bacterial Infection of The Blood
 Acute bacterial infections often lead to a local
acute inflammatory reaction at the site of
inoculation. Entry of bacterial toxins or bacteria
into the blood may lead to:
1.
2.
3.
4.
Toxemia
Bacteraemia
Septicemia
Pyaemia
Bacteraemia

is the presence of bacteria in the blood stream
without multiplication.

The blood is normally a sterile environment, so
the detection of bacteria in the blood is always
abnormal.

These are usually destroyed by antibodies and
complement and by the cells of the reticuloendothelial system in blood (monocytes), spleen,
liver, etc.
Bacteraemia
However, they may rarely settle in various parts of
the body causing lesions e.g:
1. Acute hematogenous osteomyelitis due to Staph.
aureus derived from a minor septic focus e.g skin
boil.
2. Subacute bacterial endocarditis due to Strept.
viridans derived from a septic tooth.
3. Osteomyelitis complicating typhoid fever.
Septicemia

The presence and multiplication of highly virulent
bacteria in the blood accompanied by severe
toxemia.

It is a serious condition that occurs most
commonly in association with infections by
Strept. hemolyticus
Septicemia
Pathological features:
1. Peticheal hemorrhages in
the skin, mucous
membranes and serous
membranes due to damage
of the capillary
endothelium by
bacterial toxins
Septicemia
2. The blood is more fluid than normal and
postmortem clotting does not occur, due to the
effect of hemolysins and fibrinolysins
respectively.
3. The spleen is moderately enlarged and
extremely soft.
The red pulp is congested and easily washed out
by running tap water (diffluent).
Microscopically, it is heavily infiltrated by
neutrophils (acute splenic swelling).
Septicemia
4. Acute bacterial
endocarditis may
occur due to invasion
of heart valves by
bacteria. This may be
followed by systemic
pyemia
5. Manifestations of
acute toxemia
Pyaemia
A condition in which multiple small abscesses (pyemic
abscesses) form in various organs as a result of
impaction of septic emboli.
Pathogenesis:
1. Injury of venous endothelium or valvular
endocardium by bacterial toxins followed by
thrombosis.
2. Infection of thrombus by bacteria.
Pyaemia
3. Fragmentation of infected thrombus by proteolytic
enzymes from neutrophils leading to the
formation of septic thrombotic emboli which
circulate in the blood stream.
4. Impaction of septic emboli in small blood vessels in
various organs leading to pyemic abscesses.
Pyaemia
Types of pyemia:
1. Systemic pyemia resulting from either:
a) Septic thrombosis in sytemic veins or right
heart valves leading to pyemic abscesses in
the lungs.
b) Septic thrombosis in pulmonary veins or left
heart valves leading to pyemic abscesses in
brain, kidney, spleen and other organs
supplied by the systemic arterial circulation.
2. Portal pyemia resulting from septic
thrombosis in portal vein tribuitaries leading
to pyemic abscesses in the liver.
Pyaemia
Characteristics of
pyemic abscesses:
1. Multiple
2. Usually peripheral
3. Usually small