STAPHYLOCOCCI PROF AM KAMBAL. Staphylococci Definition: Gram +ve cocci in clusters, catalase...

of 37 /37
STAPHYLOCOCCI STAPHYLOCOCCI PROF AM KAMBAL PROF AM KAMBAL
  • date post

    21-Dec-2015
  • Category

    Documents

  • view

    218
  • download

    1

Embed Size (px)

Transcript of STAPHYLOCOCCI PROF AM KAMBAL. Staphylococci Definition: Gram +ve cocci in clusters, catalase...

  • Slide 1
  • STAPHYLOCOCCI PROF AM KAMBAL
  • Slide 2
  • Staphylococci Definition: Gram +ve cocci in clusters, catalase positive. Other gram positive cocci include Streptococci and Micrococci Differences between Staphylococci, Micrococci and Streptococci
  • Slide 3
  • Character Staphylococci Streptococci (& Micrococci) Gram StainPositivePositive ArrangementClustersChains (Micrococci) in Fours) SizeLarge 1 umSmaller 0.5 1 um CatalasePositiveNegative H 2 O 2 CatalaseH 2 O + O 2
  • Slide 4
  • Staphylococci are similar to Micrococci in shape But Staphylococci can be: a)Pathogenic b)Commensals (Normal Flora) c)Oxidative & fermentative
  • Slide 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
  • Slide 6
  • Gram Positive Cocci In Clusters Species : S.aureus : main pathogen S.epidermidis (S.albus) : opportunistic S.saprophyticus : UTI
  • Slide 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.
  • Slide 8
  • Staphylococci are divided into two main groups: 1) Coagulase +ve 2) Coagulase negative i.e. Staphylococcus aureus a) Staphylococcus epidermidis b) Staphylococcus saprophyticus
  • Slide 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
  • Slide 10
  • Coagulase Test A) A)Enzyme secreted by Staphylococcus aureus. B) B)Differentiate between Staphylococcus aureus and other Staphylococci C) C)Coagulates Plasma Fibrinogen to Fibrin in clot form D) D)Tested By: 1.Slide test for bound coagulase or clumping factor 2.Tube test free coagulase test
  • Slide 11
  • Slide 12
  • Other Tests DNAse test Phosphatase test Mannitol fermentation Novobiocin sensitivity to differentiate between S.epid. and S. saproph. which is resistant
  • Slide 13
  • Staphylococci are divided into two main groups: 1) Coagulase +ve 2) Coagulase negative i.e. Staphylococcus aureus a) Staphylococcus epidermidis b) Staphylococcus saprophyticus
  • Slide 14
  • Slide 15
  • Staph. aureusStaph. epidermidis Habitat Certain areasAll skin of skinsurface (see diagram) ColourMainly goldenWhite yellow (on Blood (on Blood agar) agar medium) Catalase+ve+ve
  • Slide 16
  • Staph aureusStaph epidermidis Coagulase+ve-ve Dnase+ve-ve Phosphalase+ve-ve Growth onYellowRed Mannitol salt agar due to fermentation of mannitol Phage typingavailable Not available Groups I, II, III (Continued)
  • Slide 17
  • Slide 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
  • Slide 19
  • Slide 20
  • 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 Human Staphylococcal Species most important are:
  • Slide 21
  • Species Frequency Coagulase Common Human of infection production habitat Other species are: S. hemolyticus Uncommon NegativeAxilla, pubes (apocrine glands) S. hominis Uncommon NegativeAxilla, 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 S. warneri Rare Negative- S. xylosis Rare Negative -
  • Slide 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 CoagulaseClots Plasma FibronolysinDigests fibrin LeucoccidinKills leucocytes HyaluronidaseBreaks down hyaluronic acid DNAaseHydrolysis DNA
  • Slide 23
  • Toxins Activity LipaseLipolytic (produces opacity in egg-yolk medium) Protein AAntiphagocytic Epidermolytic toxins Epidermal splitting and exfoliation A and B Enterotoxin(s)Causes vomiting and diarrhoea Toxic shock syndromeShock, rash, desquamation toxin - 1 Virulence Factors: (Continued) B.Other virulence factors include: 1.Peptidoglycan of the cell wall 2.Teichoic acid
  • Slide 24
  • Pathogenecity Or Infections Caused By: Staph. aureus 1) 1)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
  • Slide 25
  • Toxic epidermal necrocysis S.S.S.S. = Staphylococcus Scalded Skin Syndrome 3)Deep Infections Septicaemia, Endocarditis Pyaemia Osteomyelitis Infection of bone Pneumonia 2)Skin Exfoliation Due to an enterotoxin produced in the food before ingestion. An intoxication not infection 5)Toxic Shock Syndrome 4)Food Poisoning
  • Slide 26
  • Slide 27
  • Slide 28
  • 1l 1 = Interlukin I TNF = Tumour necrosis factor
  • Slide 29
  • Slide 30
  • Slide 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 Acidpenetrate well in bones 4.Vancomycinif the organism is resist to methicillin (MRSA) 5.Erythromycin 6.Clindamycin 7.Rifampicin
  • Slide 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.
  • Slide 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.
  • Slide 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.
  • Slide 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.
  • Slide 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
  • Slide 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