This document summarizes key information about Staphylococcus bacteria. It describes the history of Staphylococcus discovery and classification. It outlines the typical characteristics of Staphylococcus including being gram positive cocci that form clusters and produce catalase. The three main pathogenic species - S. aureus, S. epidermidis, and S. saprophyticus - are identified along with their roles in infection. Methods for laboratory diagnosis including culture-based identification and biochemical tests are also summarized.

1. Systematic Bacteriology
Omdurman Islamic University
Faculty of Medical Laboratory sciences

2. History:
 It was called Staphylococcus for the first time
in 1880 by Alexander Ogston (a Scottish
Surgeon) .
 Isolated and provided the first taxonomic
description of Staphylococcus in 1884 by
Rosenbach and gave the name
Staphylococcus pyogenes.
 Evans, Bradford and Niven (1955) divided
facultative anaerobic cocci and obligate
aerobes into the genus Staphylococcus and
Micrococcus, respectively, based on the
oxidation–fermentation (OF) test for glucose

3. General Characteristics:
 Gram positive cocci non spore-forming non-motile,
spherical cells, usually arranged in grape-like
clusters
 Single cocci , pairs, tetrads and chains are seen in
liquid Cultures.
 Can readily grow in ordinary media under aerobic
and facultative anaerobic condition.
 Young cocci stain strongly gram-positive, on aging
many Cells become gram-negative
 Non motile, non spore forming and non capsulated
organism
 Catalase positive, able to grow on agar contain 7-

4.  Grow most rapidly at 37 ºC but form pigment
best at room temperature of 20-25 ºC
 Colonies in solid media are round, smooth,
raised and glistening.
 Some of them are normal flora of the skin and
mucus membrane of human.
 Produce catalase, which differentiate them
from the Streptococci.
 Relatively resistant to drying , heat, and 9%
NaCI, but readily Inhibited by 3 %
hexachlorophene

5. Normal habitat:
 Staphylococcus are widely distributed in
the environment, they from part of the
normal microbial flora of the skin, upper
respiratory tract and intestinal tract.
 S. aureus is carried in the nose of 30-
40% or more of health people.

6. Antigenic structure:
 Peptidoglycan ( Mucopeptide): polysaccharide (A) –
phosphate teichoic acid, provide the rigid
exoskeleton of the cell wall. It is important in the
pathogenesis.
 Protein (A) – similar to polysaccharide (A), it occur
in S .aureus only (unique) – (React with FC region
of IgG) both are virulence factor) (prevent
complement activation).
 Capsule: Anti- phagositic property
 Enzymes.
 Toxins.

7. MRSA
 Although methicillin-resistant S. aureus
(MRSA) strains are not necessarily more
virulent than methicillin-sensitive S. aureus
strains, some MRSA strains contain factors or
genetic backgrounds that may enhance their
virulence or may enable them to cause
particular clinical syndromes.

8. Toxins and enzymes:
 Lipase: that break down fat or lipid in the skin help
organism to spreading in tissue.
 DNAse: destroy the DNA.
 Hyaluronidase: Has action in hyaluronic acid in
connective tissue help S .aureus to spreading in
the tissue (spreading factor).
 ß. Lactamase: (Antibiotic – in activating enzyme)
that lead to penicillin resistant.
 Staphylokinase: cause fibriolysis.
 Coagulase: enzyme that clots plasma and coats
Staphylococcal cell, which prevent the bacteria
from phagocytosis.

9. Toxin and enzyme:
 Catalase: produce by staphylococcus species
use to differentiate Staphylococcus from
Streptococcus).
 Leucocidin: ( break or lyses or kill WBCs).
 Haemolysin (lytictoxin) exotoxin that destroying
RBCs and plat test.
 Exofoliative toxin: lead to scalded skin
syndrome (cause peeling of the skin).
 Pyogenic exotoxin: cause fever, hypotension
shock in genital tract of female.
 Enterotoxin: cause food poisoning (heat stable
toxin).
 Clumping factor: A surface compound that is
responsible for

10. The three main species of clinical
importance
 - S. aureus (pathogenic)
 - S. epidermides (non pathogenic)
 - S. Saprophyticus (opportunistic)

11. Pathogenicity:
 infection of skin and subcutaneous tissue
 Abscess.
 Wound infection.
 Breast abscess (Mastitis).
 Newborns impetigo (rash).
 Scalded skin syndrome. (peels).
 Secondary infection of insect bites.
 Conjunctivitis

12.  Cross infection of hospital (Pneumonia).
 Toxic shock syndrome. Due to colonization of S.
aureus especially in the vagina.
 Disease of gastrointestinal tract (Food poisoning:
Caused by enterotoxin produced by S.aureus.
 Osteomylitis.
 Septicaemia.
 S. saprophyticus: Relatively common cause of
urinary tract infections in young women
 S. epidermidis: occasional cause of infection often
associated with implanted appliances and devices

13. Lab diagnosis:
 Specimen: depending on the site of infection.
 Microscopy: Gram positive cocci (cluster or
pairs or single) non motile, non spore forming &
non capsulated organism.
 Culture: ( Facultative anaerobic, 37 ºC, pH 7.2).
 On Blood agar:
 produce yellow to cream 1- 3 mm in diameter
some strain are ß –haemolytic, colony are
slightly raised, smooth & shine.
 On Mannitol salt agar: (7- 10% NaCl)
differential & selective media for isolation or
recoveries S. aureus from faecal specimen S.
aureus produce small yellow calonies.

14. Lab diagnosis:
 On polymyxin agar: selective media for S.
aureus.
 On Mac conkey agar: Produce small colonies
(0.1 – 0.5mm) after over night incubation at 35 –
37 ºC most strain are non lactose fermenter.
Biochemical test:
 - Catalase + ve.
 - Coagulase + ve. (S. aureus).
 - DNAse + ve. (S. aureus).
 - Sugar fermentation G L M S
 + d + -

15. Lab diagnosis:
 Antimicrobial sensitivity: Antibiotic with activity
against S. aureus include:
 Vancomycin.
 Cephalosporin
 Penicillin
Control:
 Avoid contamination of food.
 Avoid direct contact with carriers.
 Sterilized the surgical instruments
 personal hygienic practice.

17. Mannitol salt agar

18. Catalase test

19. Coagulase test

20. DNAse test