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Staphylococcus

- gram positive

- Facultative anaerobic cocci

- cells occurs singly and in pairs

- grape-like cluster

- non motile

- non capsule

- non spore forming

cell wall contain techoic acid

- Ribitol techoic acid ( polysaccharide A ) in Stapyhlococcus aureus

- glycerol techoic acid ( Polysaccharide B ) in S. epidermidis

Normal Flora

- Skin

- Mucous Membranes ( nasal passage )

- Urinary Tract ( URT )

- GIT

Staphylococcus Aureus

- Dnase test

To identify S. Aureus -

produce deoxyribonuclues enzyme , in medium agar contain DNA & Clear areas dues to DNA hydrolysis after flooding the plate with hydrochloric acid

S. Aureus has

* coagulase test

* Latex agglutination

* Detection of clamping factors and / or protein A

Clinical Syndrome

* Cutaneous Infection

- Folliculitis

- Furuncles ( boils )

- Carbuncles

- Impetigo

- Wound Infection

* Toxin Infection

- scaled Skin Syndrom

- toxic - Shock syndrome

- food poisoning

* Other Infection

- Pneumonia

- Bacteremia

- Endocarditis

- Septic arthritis

Antibiotics Sensitivity

- Penicillins*

- Macrolides

- Fusicid Acid

- Cephalosporins

- Vancomycin ( Drug Of choice ) Because Penincilin and Methicillin resistance to S. Aureus

Coagulase - Negative Staphylococci

Staphylococcus Saprophyticus

- Cause urinary tract Infection UTI in young women

- Many strains Ferment manitol

Staphylococcus Epidermidis

- CNS pathogen

- Endocarditis

- Bacteraemia ( Infection Cannule )

Novobian Susceptible Test

- To differentiate S. Saprophyticus that are resistant from others that are sensitive / susceptible to this test.

Microccus Species

- Inhabits the skin and enviroment

- usually non pathogenic

Clinical significance

- Be found in burns , wound & respiratory statement

- Culture Contamination

- Bacteremia , Endocarditis

Bacitracin Sensitivity

- To differentiate micrococcus from staphylococcus species

- Bacitracin inhibit the growth of microccus

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gram positive cocci
2 families :
Micrococcaceae & Streptococceae
- species :
S. aureus
S. epidermidis
S. saprophyticus
normal habitat :
- environment
- normal flora
~ skin
~ mucous membrane
~ URT
~ GIT
Pathogenecity :
- Conjuctivitis
- Food poisoning
Virulence factor :
- Catalase
- Coagulase
- Lipase

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Nabila Shahirah

Staphylococci can cause many form of infection.
General: Staphylococcus
Species:
s.aureus
s.epidermis
s.hominis

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Other enzymes produced by staphylococci include a hyaluronidase, or spreading factor ; a staphylokinase resulting in fibrinolysis but acting much more slowly than streptokinase; proteinases and B-lactamase

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Staphylococcus - gram positive. They form clumps.
Clinical Manifestations -
1) causes superficial skin lesions and localized abscesses in other sites.
2) causes deep-seated infections, such as osteomyelitis and endocarditis and more serious skin infections.
3) cause of hospital acquired (nosocomial) infection of surgical wounds and, with S epidermidis, causes infections associated.
Treatment -
penicillinase-resistant B-lactams.
Hospital acquired infection is often caused by antibiotic resistant strains and can only be treated with vancomycin.

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Enzyme
S aureus can express proteases, a lipase, a deoxyribonuclease (DNase) and a fatty acid modifying enzyme (FAME).
The first three probably provide nutrient for bacteria.

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Membrane damaging toxins :
1) alpha toxin
- characterized and most potent membrane-damaging toxin of staphylococcus is alpha toxin .
- susceptible cells have a specific receptor for alpha toxin which allow low concentrations
- in human ,platelets and monocytes are particularly sensitive to alpha toxin .
- secondary reactions ensue ,causing release of eicosanoids and cytokines which trigger production of inflammatory mediators .
- symptoms of septix shock that occur during severe infections caused by staphylococcus aureus.

2)Beta toxin
- sphingomyelinase which damages membranes rich in this lipid .
- the classical test for beta toxin is lysis of sheep erthrocyte .
- some of the phages that inactivate the beta toxin gene carry the determinant for an enterotoxin and staphylokinase .
- suggesting that the toxin is important in the pathogenesis of mastitis .

3)peptide toxin
- a very small peptide toxin produced by most strains of S.aureus .
- produced by S.epidermidis and S.lugdunensis .

4) y-toxin and leukocidin
- two component protein toxins that damage membranes of susceptible cells .
- the B and C components from a leukotoxin with poor hemolytic activity ,whereas the A and B component are hemolytic and weakly leukotoxic .
- isolated from severe dermonecrotic lesions express this toxin.
- PV leukocidin cause dermonecrosis when injected subcutaneously .
- concentration below that causing membrane damage ,the toxin releases inflammatory mediators from human neutrophils ,leading to degranulation .

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S. Aureus
Laboratory Features
Specimens :
1-Pus and swab from infected sites
(From pyogenic lesions)
2-Sputum
(From respiratory infection)
3-CSF -cerebrospinal fluid
(From meningitis)
4-Blood for culture
(From septicaemia)
5-Faeces
(Food poisoning)
6-Nasal Swab
(From suspected carriers)

ANTIMICROBIAL SENSITIVITY

•Penicillins
•Macrolides
•Fusidic acid
•Cephalosphorins
•Vancomycin
* Used to select effective drugs for treatment
* Not inducated if sensitivity pattern of pathogen can be predicted

•Antimicrobial susceptibility test measure the ability of an antibiotic or other antimicrobial agent to inhibit bacterial grow in vitro.

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GENERAL INFO
micrococcus
stomatococcus
planococcus
-staphylococcus type: s.aureus
s.epidermis
s.saprophyticus
s.haemolyticus
s.hominis
s.warneri
s.intermedius
s.hyicus

Normal habitat
-Environment
-skin
-mucous membranes
-URT
-GIT

staphylococcus aureus
pathogenicity:
-conjunctivitis
-secondary infections-insect bites,ulcers,burns,wounds
-Pneumonia and empyema
-mastitis(inflammation of breast)
food poisoning

Lab diagnosis
macroscopic morphology
-culture
.facultative anaerobe
grow well aerobically and enriched atmosphere
35-37•c
-BA and choc Agar
creamy white colony
smooth,round,slightly raised
.On macconkey agar
not grow
lactose fermenter

Mannitol salt agar
useful selective differential medium for recovering s.aureus from faecal specimens
food poisoning

virulence factors
lipase-breakdown fat
staphylokinase-causes fibrinolysis
leukocidin-kill WBCs
Exotoxin-destroy RBC & platelets
Enterotoxin-B-causes food poisoning

Laboratory Features
pus swab-infected sites
sputum
csf
blood
faeces

Lab diagnosis
microscopic morphology
staphyle grape like
non motile
non capsulate
non spore forming

Dnase test
to identify s.aureus which produces deoxyribonuclease(Dnase) enzyme

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staphylococcus

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staphylo

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staphylococcu

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staphyl

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staphy

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stap

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sta

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Staphylococcus have 40 species.
-common species
1)s.aureus
=Pathogenic and commensal found in nose.
2)s.epidermidis
=is a commensal of skin,but can cause severe infection in immune suppressed patients.

3)s.saprophyticus
=is part of the normal vagina flora,is predominantly implicated in gentourinary tract infection.

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Staphylococcus

• have 2 families
ⅰ. Micrococcaceae
ii . Streptococcaceae

• have 24 species
• common only 3;
- S. aureus
- S. epidermidis
- S. saprophyticus

• normal habit in environment
• normal flora of - skin, mucuoue membranes, URT, GIT

Pathogenicity :
1. Abscesses
2.

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Juliza Jumari Discussion class for Staphylococcus sp

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Juliza Jumari Discussion class for Staphylococcus sp

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1. write your name
2. share your knowledge about Staphylococcus sp.

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Diagnostic laboratory test
A. Specimens
Surface swab pus or aspirate from abscess, blood, tracheal aspirate or spinal fluid for culture, depending on localization of the process.
B . Smears
Staphylococci appear gram positive cocci in cluster in Gram -stained smear of pus or sputum. It is not possible to distinguish saprophytic (S. Epidermidis) from pathogenic ( S. Aureus ) organisms on smears.
C. Culture
Specimen planted on bloof agar plates giv rise to typical colonies in 18 hours at 37°c .
🔹Catalase test
Used to detect presence of cytochrome oxidase enzyme. A drop of 3% hydrogen peroxide solution is placed on a slide and small amount of the bacteria growth is placed in the solution . The formation of bubbles (release of oxygen ) positive test result.
🔹 Coagulase test
Using plasma mixed with sterile broth. If clots form ,the result is positive. Coagulase positive staphylococci considered pathogenic for human.
🔹 Susceptibility testing