STAPHYLOCOCCI

1
STAPHYLOCOCCI

• PROF AM KAMBAL

2
Staphylococci

• Definition
• Gram ve cocci in clusters, catalase positive.
• Other gram positive cocci include Streptococci
  and
• Micrococci
• Differences between Staphylococci, Micrococci and
• Streptococci

3

• Character Staphylococci Streptococci
• ( Micrococci)
• Gram Stain Positive Positive
• Arrangement Clusters Chains
• (Micrococci) in
• Fours)
• Size Large 1 um Smaller
• 0.5 1 um
• Catalase Positive Negative
• H2O2 Catalase H2O O2

4

• Staphylococci are similar to Micrococci in shape
• But Staphylococci can be
• a) Pathogenic
• b) Commensals (Normal Flora)
• c) Oxidative fermentative

5

• While Micrococci are
• a) Commensal (Normal flora of skin)
• b) Only oxidative (Non fermentative)
• Can be differentiated from Staphylococci by
  oxidation, fermentation reactions (O F) test

6
Gram Positive Cocci In Clusters

• Species
• S.aureus main pathogen
• S.epidermidis (S.albus) opportunistic
• S.saprophyticus UTI

7
Laboratory Characteristics

• Morphology
• Culture ordinary media,aerobic/ non aerobic,
  positive catalase reaction.
• Colonies
• S.aureus golden yellow-white
• S.epidermidis white, no pigment
• Both tolerate 5-10 NaCL.

8

• Staphylococci are divided into two main groups
• 1) Coagulase ve 2) Coagulase
  negative
• i.e.
• Staphylococcus aureus

a) Staphylococcus epidermidis
b) Staphylococcus saprophyticus
9
Differentiating Tests

• Coagulase test main test
• S.aureus coagulase positive
• S. epidermidis and albus coagulase negative
• Two types of coagulase tests
• Tube coagulase
• Slide coagulase

10
Coagulase Test

• Enzyme secreted by Staphylococcus aureus.
• Differentiate between Staphylococcus aureus and
  other Staphylococci
• Coagulates Plasma Fibrinogen to Fibrin in clot
  form
• Tested By
• 1. Slide test for bound coagulase or clumping
  factor
• 2. Tube test free coagulase test

11
(No Transcript)
12
Other Tests

• DNAse test
• Phosphatase test
• Mannitol fermentation

• Novobiocin sensitivity to differentiate between
  S.epid. and S. saproph. which is resistant

13

• Staphylococci are divided into two main groups
• 1) Coagulase ve 2) Coagulase
  negative
• i.e.
• Staphylococcus aureus

a) Staphylococcus epidermidis
b) Staphylococcus saprophyticus
14
(No Transcript)
15

• Staph. aureus Staph. epidermidis
• Habitat Certain areas All skin
• of skin surface
• (see diagram)
• Colour Mainly golden White
• yellow (on Blood (on Blood
  agar) agar medium)
• Catalase ve ve

16
(Continued)

• Staph aureus Staph
• epidermidis
• Coagulase ve -ve
• Dnase ve -ve
• Phosphalase ve -ve
• Growth on Yellow Red
• Mannitol salt agar
• due to fermentation
• of mannitol
• Phage typing available Not available
• Groups I, II, III

17
(No Transcript)
18
Staphylococcus aureus

• Carried by 20 50 of healthy people on the
  skin mainly in
• a. Nose
• b. Axilla
• c. Perineum
• d. Throat
• e. Gut

19
(No Transcript)
20
Human Staphylococcal Species most important are

• Species Frequency Coagulase
  Common Human
• of Infection Production Habitat
• S. aureus Common Positive
  Anterior nares,
• perineum
• S. epidermidis Common Negative
  Anterior nares, head, axilla,
  arms and legs
• S.saprophyticus Common Negative
  Urinary tract

21

• Species Frequency Coagulase Common
  Human
• of infection production
  habitat
• Other species are
• S. hemolyticus Uncommon
  Negative Axilla, pubes
• (apocrine glands)
• S. hominis Uncommon
  Negative Axilla, pubes
• (apocrine glands)
• S. simulans Uncommon
  Negative -
• S. auricularis Rare
  Negative Ear canal
• S. capitis Rare Negative
  Scalp, forehead
• (sebaceous gland)
• S. cobnii Rare
  Negative -
• S. saccharoly- Rare
  Negative -
• ticus

22
Virulence Factors

• A. Toxins and toxic components produced by
  Staphylococcus aureus
• Toxins Activity
• Haemolysins a, B, y and - Cytolytic, lyse
  erythrocytes of various animal species
• Coagulase Clots Plasma
• Fibronolysin Digests fibrin
• Leucoccidin Kills leucocytes
• Hyaluronidase Breaks down hyaluronic acid
• DNAase Hydrolysis DNA

23
Virulence Factors (Continued)

• Toxins Activity
• Lipase Lipolytic (produces opacity in egg-yolk
  medium)
• Protein A Antiphagocytic
• Epidermolytic toxins Epidermal splitting and
  exfoliation
• A and B
• Enterotoxin(s) Causes vomiting and diarrhoea
• Toxic shock syndrome Shock, rash, desquamation
• toxin - 1

• Other virulence factors include
• 1. Peptidoglycan of the cell wall
• 2. Teichoic acid

24
Pathogenecity Or Infections Caused By Staph.
aureus

• Superficial Infection
• 1. Pustules
• 2. Boils
• 3. Carbuncles
• 4. Impetigo
• 5. Collection of pus
• 6. Abscesses
• 7. Wound infection (Hospital Acquired)
• 8. Paronychia Infection of nail bud

25
2) Skin Exfoliation

• Toxic epidermal necrocysis
• S.S.S.S. Staphylococcus Scalded Skin Syndrome
• 3) Deep Infections
• Septicaemia,
• Endocarditis
• Pyaemia
• Osteomyelitis Infection of bone
• Pneumonia

4) Food Poisoning

• Due to an enterotoxin produced in the food before
  ingestion.
• An intoxication not infection
• 5) Toxic Shock Syndrome

26
(No Transcript)
27
(No Transcript)
28
1l 1 Interlukin I TNF Tumour
necrosis factor
29
(No Transcript)
30
(No Transcript)
31
Treatment Drain Pus if any Antibiotics

• Antibiotic Sensitivity (Staphylococcus aureus)
• 1. Penicillin 95 if sensitive, it is the
  best drug
• 2. Flu/Cloxacillin (Methicillin) Drug of choice
• 3. Fucidic Acid penetrate well in bones
• 4. Vancomycin if the organism is resist to
  methicillin (MRSA)
• 5. Erythromycin
• 6. Clindamycin
• 7. Rifampicin

32

• MRSA Methicillin Resistant Staphylococcus
  aureus
• MRSA Also Resistant to Cloxacillin
  Flucloxacillin
• Treatment For MRSA Vancomycin
• Treatment of Staphylococcus aureus
• 95 Resistant to Penicillin so treated by
  Cloxacillin if Resistant to Cloxacillin or
  Methicillin MRSA so treat with Vancomycin.

33

• MRSA Methicillin Resistant Staphylococcus
  aureus
• MRSA Also Resistant to Cloxacillin
  Flucloxacillin
• Treatment For MRSA Vancomycin
• Treatment of Staphylococcus aureus
• 95 Resistant to Penicillin so treated by
  Cloxacillin if Resistant to Cloxacillin or
  Methicillin MRSA so treat with Vancomycin.

34
M.R.S.A

• Methicillin and cloxacillin resistant S.aureus.
• Due to mec A gene which codes for PBP 2a with low
  affinity to beta lactam antibiotics nosocomial
  infections.
• Treatment vancomycin for systemic infections
  only.

35
B) Staphylococcus saprophiticus

• It causes urinary tract infection in young
  female.
• Coagulase Negative Staphylococci (it is
  novobiocin resistant)
• The commonest coagulase negative is
• Staph. epidermidis
• Pathogenesis
• They produce very small amounts of toxins.
• Pathogenesis is mainly due to production of
  (slime) which consists of
• a. Polysaccharide
• b. Techoic acid enhanced by presence of
  fibrinogen.
• This makes them sticky on biomaterial like
  catheters. Sticky material called is Biofilm.

36

• They Cause
• 1. Endocarditis in artificial valves shunts.
• 2. Infections of spitz holter valves connecting
  brain ventricle with jugular vein
• 3. Infection of cannulae
• 4. Infection of Intravenous catheters
• 5. Infections of prosthesis
• e.g. Artificial valves (heart)
• Orthopaedic fixing nails
• 6. Infection in premature babies (Bacteriaemia)
• 7. Infection in Oncology patients
• 8. Staphylococcus saprophyticus causes urinary
  infection in young females

37

• Treatment of Coagulase Negative Staphylococci
  Staphylococcus epidermidis and others
• Depends on testing antibiotics sensitivity on the
  isolates
• But Vancomycin is the drug of choice for severe
  serious infection