This document discusses Gram positive bacteria. It begins by providing background on bacteria in general and then focuses on classification based on staining properties. Gram positive bacteria retain crystal violet dye after staining and have a thick peptidoglycan cell wall layer. Some common disease-causing Gram positive bacteria are Staphylococcus aureus, Streptococcus pneumoniae, Bacillus anthrax, Clostridium tetani, Corynebacterium diphtheriae, and enterococci. Signs and symptoms of Gram positive bacterial infections include draining sinus tracts, erythema, fever, and abscesses. Laboratory tests like blood cultures and joint aspiration can help detect infections. Most Gram positive infections can be

1. GRAM POSITIVE
BACTERIA
PRESENTED BY SARA HUSSAM
M.PHILL MICROBIOLOGY 2ND SEMISTER

2. BACTERIA
• Bacteria are single-cell organisms
that are neither plants nor animals.
They usually measure a few
micrometers in length and exist
together in communities of millions.

3. Bacteria are thought to have been
the first organisms to appear on
earth, about 4 billion years ago. The
oldest known fossils are of bacteria-
like organisms.
Some bacteria are harmful while
others are beneficial and can serve
for medicinal purpose.

4. CLASSIFICATION OF BACTERIA
• There are many bases of classification of
bacteria like
• Classification on the bases of shape.
• Classification on the bases of cell wall
composition and their staining.

5. ON THE BASIS OF STAINING OF
BACTERIAL CELL WALL
• Discovered by H.C. Gram in 1884.
• It allows a large proportion of clinically
important bacteria to be classified as either
Gram positive or negative based on their
morphology and differential staining
properties.

6. GRAM POSITIVE AND GRAM NEGATIVE
BACTERIA
GRAM POSITIVE BACTERIA
Retains crystal violet dye
after staining
GRAM NEGATIVE
BACTERIA
Do not retain crystal violet
dye after staining

8. GRAM POSITIVE BACTERIA:
The Gram positive bacteria have a
cell wall composed of a thick layer
of a particular substance (called
peptidologlycan).

10. Gram positive bacteria includes
1)cocci (round shaped)
2) bacilli (rod shaped)

11. Some of the common diseases causing
Gram positive bacteria are:
staphylococcus aureus, streptococcues
pneumoniae, bacillus anthrax,
clostiridium tetani, corynebacterium
diphtheria, enterococci

12. STAPHYLOCOCCUS AUREUS:
S. aureus can cause inflammatory
diseases including skin infections,
pneumonia, endocarditis, septic
arthritis, osteomyelitis, and
abscesses

13. STREPTOCOCCUS PNEUMONIAE:
Streptococcus pneumoniae is a
gram-positive, encapsulated,
lancet-shaped diplococci most
commonly causing otitis media,
pneumonia, sinusitis, and
meningitis

14. BACILLUS ANTHRACIS:
Bacillus anthracis is a gram-positive
spore-forming rod that produces
anthrax toxin resulting in an ulcer
with a black eschar.

15. CLOSTRIDIUM TETANI:
Clostridium tetani is a gram-positive
spore-forming rod that causes
tetanus, which is a medical
emergency and cause severe
tightening of muscles all over the
body and can cause locking of the
jaw making the mouth impossible
to open

16. CORYNEBACTERIUM DIPTHARIA
Corynebacterium diphtheria is a gram-
positive club-shaped rod which can
cause pseudomembranous pharyngitis,
myocarditis and neural tissue damage.

17. ENTERO COCCI:
Entero cocci is a gram
positive bacteria that cause biliary
tract infections and UTIs

18. SIGNS AND SYMPTOMS
• Draining sinus tracts
• Erythema
• Fever
• Superficial abscesses
• Warmth

19. LABORATRY TESTS
• Once a gram-positive organism infection is
suspected, these laboratory studies are useful:
• CBC
• Blood cultures
• Coagulase test
• Joint aspiration if a septic joint is suspected

20. TREATMENT
• Most infections due to Gram-
positive organisms can
be treated with quite a small
number of antibiotics. Penicillin,
cloxacillin, and erythromycin
should be enough to cover 90 per
cent of Gram-positive infections.