1. Staphylococcus Streptococcus
Lab : 7
Gram Positive Cocci
Staphylococcus Streptococcus
Gram Negative Cocci
Neisseria

2. Staphylococci
includes at least 40 species. Most are harmless and reside normally on the skin and mucous membranes of humans and other organisms. also they are a small component of soil microbial flora.
Three species of staphylococci have medical importance :
1- S.aureus :pathogenic & occasionally commensally found in nose.
2- S.epidermidis(albus):non pathogenic & commensals in skin.
3- S.saprophyticus (citrus):cause UTI in female & occasionally commensally found in skin.

3. General characters Microscopical appearance G+ cocci
Arranged in cluster (Grape – like).
Non motile
Non spore forming
Non capsulated
Macroscopically appearance
1-Cultural characteristic:
Grow on most type of media and produce large (2mm) smooth.
Opaque . Circular colonies.
Highly tolerate to high concentration of NaCl
Non fastidious, Facultative anaerobic .
2- Biochemical tests :
Carbohydrate Fermentative without gas production .
Catalase positive.
Urease positive.
Nitrate reductase positive.

4. Staphylococci can be differentiated from other aerobic gram - +
Staphylococci can be differentiated from other aerobic gram
positive cocci by a positive catalase test.
The test is performed by adding bacterial cells from a colony to a drop of 3% hydrogen peroxide.
The appearance of bubbles (right) indicates the enzyme catalase while catalase negative bacteria give no reaction (left).

5. Staphylococcus aurous
Characteres
Microscopically appearance: as above.
Macroscopically appearance
1-Cultural characteristic:
* Golden colonies on nutrient agar.
* Ferment mannitol.
* Β-hemolytic on blood agar.
2-Biochemical tests :
* Production of coagulase.
* Gelatin liquefied ( hydrolysis ) .
Novobiocin sensitivity .
Production of phosphatase.
Production of DNase.

6. Typical colonies of staphylococcus epidermidis on right showing porcelain-white colonies as compared to S. aureus on the same medium (left)
the golden appearance of the colonies. This clear distinction in colony color is not seen at all times.

7. Growth on Mannitol-Salt agar differentiates S. aureus
catalase positive gram positive cocci like s. epidermidis. S. aureus grows
as shown here on an agar medium containing 7.5% NaCl which inhibits
the growth of many other organisms. S. aureus also can ferment mannitol
into acid detected here by the change in pH indicator from red to yellow.
(right)

8. Young colonies of Staphylococcus aureus showing beta hemolysis

9. Coagulase test : 1 - Slide Coagulase test.
The most important distinction among staphylococci is whether or not
they produce the enzyme coagulase. S. aureus is the most common pathogen among the catalase positive gram positive cocci and is differentiated from other staphylococci by the coagulase test. Cogulase acts on fibrinogen and causes the clumping of the bacteria (right).

10. - + 2 - Tube Coagulase test.
The tube coagulase test detects both free and cell bound coagulase of S. aureus. .
Coagulase acts on prothrombin and fibrinogen in plasma and forms a fibrin clot (left). - +

11. Novobiocin sensitivity test:
S. Saprophyticus can be distinguished from other species of coagulase negative staphylococci by their resistance to novobiocin (right). The novobiocin susceptible staphylococcus is on the left.

12. S.saprophyticus (citrus) Mannitol Fermentation Reaction to Novobiocin
S.epidermidis
(albus)
S.aureus +
Catalase test _
Coagulase test
Mannitol Fermentation
White to Yellow
White
Gold-Yellow
Colour
None
Beta
Hemolysis test
Resistant
Sensitive
Reaction to Novobiocin

13. Streptococci
many streptococcal species are nonpathogenic, and form part of the commensal human microbes of the mouth, skin, upper respiratory tract, intestine and genitourinary tract .
Furthermore, streptococci are a necessary ingredient in producing ("Swiss") cheese.
Many species of streptococcus are responsible of human infection .

14. Streptococcus pyogens
known as Group A Streptococcus (GAS) is the causative agent in Group A streptococcal infections.
Microscopically appearance:
G +
Spherical cocci
Arranged in chains of varying
length .
Non motile.
Non spore forming.
Non capsulated

15. Small colonies (pinpoint).
Macroscopically appearance
1-Cultural characteristic :
Small colonies (pinpoint).
β -hemolysis (complete hemolytic)on blood agar
Semi-transperant .
Low convex

16. 2-Biochemical tests :
Bile solubility –ve (turbid broth).
Ferment different kind sugar with gas production .
Gelatin hydrolysis : + ve .
Sensitive to bacitracin (antibiotic) .

17. Streptococcus pneumoniae (pneumococcus)
It founds as a normal flora (in 5-40%) of population but it could cause many diseases e.g. pneumonia , otitis media ,sinusitis ,bronchitis ,meningitis ,bacteremia.

18. Microscopically appearance:
G +
Spherical diplococci
lancet shape
Non motile.
Non spore forming.
capsulated (polysaccharide) so it is highly resistant to phagocytosis , and also according to capsule can be subdivided to specific anti sera-sera-spp.

19. glistening colonies about 1 mm in diameter.
Macroscopical appearance
1-Cultural characteristic :
α -hemolysis (partial hemolytic) on blood agar ( greenish zone around colony).
glistening colonies about 1 mm in diameter.
Colonies appear initially with plateau-type , then start to collapse in the centers when autolysis begins .

20. Alpha (α) hemolysis (blood agar around bacterial colonies looks greenish-brown, indicating partial breakdown and consumption of hemoglobin)
Mixed culture from a throat swab; note several β-hemolytic colonies

21. o 2-Biochemical tests : Nitrate reduction : – ve .
Inulin fermentation : + ve .
Capsule reaction (Qulleng reaction): + ve .
Bile solubility : + ve ( clear broth ) .
Optochin (antibiotic) sensitive. o

24. Bacitracin Sensitive Beta A Strepto.pyogenes resistant B
Diagnostic
fetures
Hemolysis
Lancefield groupe
Bacitracin
Sensitive
Beta A
Strepto.pyogenes
resistant B
Strepto,agalactiae
Growth in 6.5%NaCl
α or β or none D
Str.faecalis
(Enterococcus)
No growth in 6.5%NaCl
α or none
Strepto.bovis
Bile soluble
Optochin sensitive α
Not applicable
Strepto.pneumoniae
Bile insoluble
Optochin resistant
Viridans group
Diagnostic
features
Hemolysis
Lancefield
group
Bacitracin
Sensitive
Beta A
S.pyogenes
resistant B
S.agalactiae
Growth in 6.5%NaCl
α or β or none D
S.faecalis
(Enterococcus)
No growth in 6.5%NaCl
α or none
S.bovis
Bile soluble
Optochin sensitive α
Not applicable
S.pneumoniae
Bile insoluble
Optochin resistant
Viridans group

25. Neisseria
The neisseria is a large genus of commensal bacteria that colonize humans , only two are pathogenic Neisseria Meningitidis , Neisseria gonorrhea , often cause asymptomatic infections. Parasitic bacteria that grow in pairs and occasionally tetrads, thrive best at (37°C) in the animal body or serum media.
N. gonorrhoeae (also called the gonococcus), which causes gonorrhea.
N. meningitidis (also called the meningococcus), one of the most common causes of bacterial meningitis and the causative agent of meningococcal septicaemia.

26. Microscopically appearance:
G -ve,
diplococci ,
kidney shape,
non motile,
non spore forming and mostly non capsulated.

27. Macroscopically appearance 1-Cultural characteristic : Aerobic, prefer (5-10% CO2) for primary isolation on enriched media (blood or chocolate). Transparent colonies about 1-2mm in diameter, pink convex and mucoid . Selective media for Neisseria is Thyer Martin media (TMM).

29. 2-Biochemical tests : all Neisseria spp
2-Biochemical tests : all Neisseria spp. are Oxidase +ve and Catalase +ve. The differentiation among the Neisseria spp. is based on the sugar fermentation and possession of the DNase , as follows:

30. Neisseria Meningitidis
DNase
Maltose
Dextrcose
(-)
(+)
Neisseria gonorrhea
Neisseria Meningitidis