Staphylococcus

Most important bacteria for undergraduate students. This topic packs up lot of short notes and viva questions. Examiner's Favorite

1. Staphylococcus
Dr.Riyaz Sheriff

2. Staphylococcus
•Ubiquitous
•Gram positive
•Cocci
•Staphyle-Bunch of grapes
•Kokkos-Berry
•Discovered by Von Recklinghausen
•Named by Sir Alexander Ogston

3. Staphylococcus
•Pyogenic infections
•Pigment production not associated with
virulence
–Golden yellow colonies Staphylococccusaureus
–White colonies Staphylococcus epidermidis
–White colonies Staphylococcus albus
–Lemon yellow colonies Staphylococcus citreus

4. Staphylococcus aureus

6. Staphylococcus epidermidis

7. s.Aureus& S.epidermidis

8. s.Aureus& S.epidermidis

9. s.Aureus& S.epidermidis

11. Arrangements of cocci

12. Grape like cluster

13. Generally!
•Non motile
•Non sporing
•Young cultures may have capsules
•Stain with aniline dyes
•Uniformly gram positive
•L forms may be seen

14. Currentclassification
•32 species
•15 sub species
•Coagulase positive Staphylococcus aureus
•Coagulase negative
–Staph. epidermidis
–Staph hemolyticus
–Staph saprophyticus
–Staph hominis
–Staph capitis Commensal flora

15. Staphylococcusaureus
•Gram positive cocci
•Arranged in grape like
clusters
•Cluster formation is d/t
division in 3 planesand
daughter cells remain in
close proximity
•May appear in singles,
pairs or short chains
•Some bacteria may have
capsules

16. Culturecharacteristics
•Grow on ordinary media
•Temp 10-42°C. optimum is 37°C
•pH range 7.4 –7.6
•Aerobes
•Facultative anerobes
•Nutrient agar
–Large, Circular, Smooth, Shiny, Opaque & easily
emulsifiablecolonies
–Yellow pigment which does not diffuse into medium
–Pigment is carotene like lipoprotein
–Pigment production best at 22°C or when glycerol
monoacetate/ milk is incorporated into medium

17. culture characteristics (Cont'd)
•Nutrient slope
–Oil paint appearance
•Blood agar
–Marked hemolysis on sheep blood agar
–20-25% Co2
–Rabbit / Sheep blood
•Mac Conkeyagar
–Pink colonies due to lactose fermentation
•Liquid media
–Uniform turbidity
•Selective medium
–Salt milk agar
–Salt broth
–Ludlam’smedium ( Lithium chloride, Tellurite)

22. Salt milk agar

23. Biochemical reactions
•Catalase Positive
•IndoleNegative
•MR Positive
•VP Positive
•UreasePositive
•Nitrate reduction Positive
•Mannitol fermentation Positive
•Phosphataseproduction Positive

24. Indole

25. Mr/ vp

26. Ureasetest

27. Mannitol fermentation

28. Resistance
•Withstand upto60°C, die at 62°C
•Can grow upto45°C
•Can grow in medium containing 10-15% NaCl
•Resist 1% phenol for 15mins
•1% mercuric perchloridekills staphylococci in
10mins
•Aniline dyes lethal
–Crystal violet 1:5,00,000 concentration
–Brilliant green 1: 1,00,00,000 concentration
•Fatty acids inhibit growth of staphylococci

29. Penicillins & Staphylococci
•Sensitive in pre-antibiotic era
•Few strains evolved !!
•Pencillinase
•Inducible enzyme
•Plasmid mediated : Transduction / conjugation
•4 types A-D
•Newer antibiotic resistant bacteria spread far and
wide ….
•Hospital strains belong to group A

30. Resistance to drugs -Penicillin
•Changes in bacterial surface receptors (PBP2a)
•Avoids binding of antibiotic to cell wall
•Development of tolerance to penicillin
•Also includes beta-lactamaseresistance
penicillins like Methicillin & Cloxacillins:
MRSA
•Plasmid borne resistance to Erythromycin,
Tetracyclines, Aminoglycosides etc
•Cause hospital infections & epidemics 
EMRSA
•Methicillin OxacillinCefoxitin

31. Pathogenicity
•Infections
–Cocci enter via damaged skin/ mucousa/tissue
–Coloniselocally
–Evade host mechanism
–Tissue damage
•Intoxications
–Disease caused by bacterial toxins
–In vitro/ in vivo

32. virulence
•Cell associated polymers
–Cell wall polysaccharide peptidoglycan
•Rigidity and structural integrity
•Activates complement
•Induces release of inflammatory cytokines
–Techoicacid
•Antigenic component
•Adhesion
•Protect from complement mediated opsonisation
–Capsular polysacchride
•Inhibit opsonization

33. virulence
•Cell surface proteins
–Protein A
•Chemotactic
•Anti –phagocytic
•Anti-Complementary
•Induces platelet damage & hypersensitivity
–Clumping factor –Bound coagulase–slide coagulase
test
•Extracellular enzymes
–Coagulase clots human/rabbit plasma
–Coagulase enzyme + CRF coagulum (fibrinogen to
fibrinclot) –free coagulase-Tube coagulasetest

34. Slide coagulasetest

35. Tube coagulasetest

36. virulence
–Lipases
–Hyaluronidase
–Nucleases
–Protein receptors

37. Toxins
•Cytolytictoxins
–Alpha Hemolysin
–Beta Hemolysin
–Gamma Hemolysin
–Delta Hemolysin
–Leucocidin-(Panton –Valentine toxin or PVL)
•Enterotoxin
–Staphylococcal food poisoning
–Nausea , Diarrhoea, vomiting after 2-6hrs of ingestion of
contaminated food
–Heat stable toxin : 100°C for 10-40mins
–Common food products : Meat, Fish, Milk or Milk products
•A, B,C1,C2,C3,D,E & H

38. Summation of Factors
associated with virulence
Hemolysis
Gelatin liquefaction
Lipolyticactivity
Production of urease
Production of phosphatase
Coagulase formation
Mannitolfermentation

39. Toxin mediated syndromes
•TSST & SSSS toxins are called superantigens
•Potent activators of T-Lymphocytes
•Stimulate wide variety of T Lymphocyte
regardless of antigen specificity
•Excessive improper immune response,
Massive release of cytokines , TNF & INF Ɣ

40. Toxin mediated syndromes
•Toxic Shock Syndrome Toxin TSST
–Multisystem disease
–Older days : Tampon usage
–Follows infection of mucosa / site by toxin producing
strains
•Fever
•Hypotension
•Myalgia
•Vomiting
•Diarrhoea
•Mucousalhyperemia
•Rash
–TSST 1 Antibody is seen in patients recovering from TSST

41. Toxin mediated syndromes
•Exfoliative (epidermolytic) toxin SSSS
•Staphylococcal Scalded Skin Syndrome
•Exfoliative disease
•Outer layer of epidermis gets separated from
underlying tissue
•Severe form of SSSS in new born Ritter’s disease
•In older patients Toxic epidermal Necrolysis
•Milder forms
–Phemphigusneonatorum
–Bullousimpetigo

43. Staphylococcal diseases
•Skin and soft tissue infections
–Folliculitis
–Furancle
–Boils
–Abscess
–Wound infection
–Carbuncle
–Impetigo
–Paronychia
–Cellulitis
•Musculoskeletal
–Osteomyelitis
–Arthritis
–Bursitis
–Pyomyositis

45. Staphylococcal diseases
•Respiratory
–Tonsillitis
–Pharyngitis
–Sinusitis
–Otitis
–Bronchopneumonia
–Lung abscess
–Empyema
•Central nervous system
–Abscess
–Meningitis
–Intra cranial thrombophlebitis

46. Staphylococcal diseases
•Endovascular
–Bacteremia
–Septicemia
–Pyemia
–Endocarditis
•Urinary tract infection
–Uncommon
–Present with instrumentation
–Diabetes
–Significant when associated with Bacteremia

47. Bacteriophagetyping
•Strain to be typed is inoculated as lawn culture on nutrient agar
•After drying phages are applied on marked squares in a fixed
dose
•After overnight incubation cultures will be observed to be
lysedby some phages
•Phage type of strain is expressed by the phages which lysethe
bacteria
•Phage typing is important in epidemiological studies.

48. LAWN
CULTURE
PHAGE

49. Epidemiology
•Primarily colonize skin
•Respiratory & superficial infections disseminate into
environment
•10-30% carry staphylococci in nose
•10 % have staphylococcal carriage in hair& perineum
•5-10% carriage is seen in vagina
•Transmission of infection can be by contact, direct or
through fomites, by dust or by airborne droplets
•Nosocomialcross infection is very important 
resistant strains

50. LAB DIAGNOSIS
•SPECIMEN COLLECTION
•Microscopy
•Culture
•Identification
–Catalase test
–Coagulase test
•Slide
•Tube
–Antibiotic sensitivity
–Phage typing

51. Treatment
•Penicillin is drug of choice
•Methicillin/ cloxacillinin penicillin resistant cases
•For MRSA Vancomycin
•Vancomycin, Teicoplaninresistant strains have appeared
•Superficial infection local application with bacitracin,
Chlorhexidineor Mupirocin
•Very resistant cases & chronic resistant carriers 
Rifampicinalong with oral antibiotic

52. Coagulase negative
Staphylococcci
•Staphylococcus epidermidis
–Commensal on skin
–Can cause cystitis
–Stitch abscess, artificial heart valves, shunts, intra
vascular catheters& prosthetic appliances
•Staphylococcus hemolyticus
•Staphylococcus saprophyticus
–Uti in young women