2 BACTERIOLOGY - MANUEL

• What genera are included in the family of Micrococcaceae (4)

  Hint: SSMP

  
  

  ■Staphylococcus

  ■Stomatococcus

  ■Micrococcus

  ■Planococcus
• Based on the Gram stain result, how is the morphology of the following different:

  
  

  1.Staphylococci

  2.Micrococci

  ■ Staphylococci - Cocci in clusters (grape like)

  
  

  ■ Micrococcus - Cocci in Tetrads
• Sarcina spp. are can be identified from other members of Micrococci using Gram's stain because?

  Its cocci clusters are in packets of 8.
• What is the characteristic growth pattern of Staphylococci in BAP?


  Creamy white, pin head colonies on BAP, with characteristic hemolytic pattern based on spp.
• What are the 3 types of hemolytic patterns?

  ■Alpha - incomplete hemolysis - green zone

  ■Beta- complete hemolysis - clear zone

  ■Gamma - no hemolysis
• What is produced by Alpha-hemolytic organisms that results to its characteristic color on blood agar plates?

  ■Met hemoglobin - MHb
• This is a special hemolytic pattern characterized by incomplete hemolysis with an inner zone of complete hemolysis?

  ■Alpha-prime Hemolysis
• Staphylococcus aureus is characterized by what type of hemolytic pattern on BAP?

  ■Beta hemolysis
• Differentiate the growth patterns of the following organisms in LSS:

  1. Staph. aureus

  2. Staph. citreus

  3. Staph. albus


  1. Staph. aureus - Golden yellow

  2. Staph. citreus - Lemon yellow

  3. Staph. albus - Porcelain White
• What is the meaning of LSS?

  Loeffler's Serum Slant
• ■This is considered as a selective differential media for Staph. aureus and other medically important Staph. spp

  
  

  ■What is the color indicator used?

  ■What is the sugar used?

  ■What other Staph spp. [Results]?(2)

  ■ MSA - Mannitol Salt Agar

  ■ Color Indicator: Phenol red

  ■ Sugar: Mannitol

  
  

  Other Staph spp.

  ■S.aureus - yellow

  ■S.epidermidis and S. saphrophyticus - pink
• What is the inhibiting substance used in MSA?

  ■7.5% NaCl
• ■What is the test used to differentiate Non-mannitol fermenting Staphylococcus spp.?

  
  

  ■What is the result of each spp?

  ■Novobiocin Test

  
  

  ■S. epidermidis - susceptible

  ■S. saphrophyticus - resistant
• ■What test is used to differentiate Staphylococcus from Streptococcus?

  
  

  ■What reagent is used? [Indicate the percentage]

  ■What is the positive result? [Indicate the organism]

  ■Catalase test

  ■Reagent - 3% Hydrogen Peroxide

  
  

  ■Positive result: Effervescence

  ■Staphylococcus spp. (+)
• What is the precaution when performing Catalase test?

  ■Do not add 3% Hydrogen Peroxide directly on the blood agar plate, blood contains catalase!!!
• Based on Aerobic and Anaerobic growth differentiate Staph. aureus from Micrococci spp. ?

  ■Staph. aureus - grows on both aerobic and anaerobic conditions (facultative aerobe)

  
  

  ■Micrococcus - grows on aerobic conditions only (obligate aerobe)
• What drug susceptibility tests may be used to differentiate Staphylococcus spp. from Micrococci spp.?(2)

  ■Lysostaphin test

  ■Bacitracin test
• Indicate the results of each spp.

  Lysostaphin test

  ■Staph. spp. - Sensitive

  ■Micrococcus - Resistant

  
  

  Bacitracin test

  ■Resistant

  ■Sensitive
• ■What reagent is used in oxidase test?

  
  

  ■What is added in the modified oxidase test?

  
  

  ■What is the result if the organism is:

  - Staphylococcus spp.

  - Micrococci


  ■Oxidase test - tetra methyl paraphenylene diamine dihydrochloride

  ■Modified Oxidase test - addition of dimethyl sulfonamide

  
  

  Results:

  ■Staphylococcus spp. - negative

  ■Micrococcus spp. - positive
• ■What is the metabolism mechanism of the following:

  1.Staphylococcus spp.

  2.Micrococcus spp.

  ■Staphylococcus - fermentation

  ■Micrococcus - oxidation
• ■What test is used to detect the most important pathogenic determinant of Staphylococcus aureus?

  
  

  ■What are the two types of this test? [Differentiate the two based form detected]

  ■Coagulase test

  
  

  Types:

  - Slide Coagulase test - Cell bound coagulase

  - Tube Coagulase test - Free coagulase
• Reagent used in each type of coagulase test

  ■ Slide Coag. - Rabbit plasma/serum

  
  

  ■ Tube Coag - 0.5ml Rabbit plasma
• ■What anticoagulants maybe used in Coagulase test?(2)

  ■Which is the preferred anticoagulant?

  ■EDTA - Preferred

  ■Citrate - may cause false positive
• ■What is the maximum allowable time to perform tube coagulase test?

  
  

  ■The test should be checked at what time interval?

  ■Maximum of 4 hours

  ■Checked every 30mins
• ■Why is there a need for the maximum allowable time when performing coagulase test?

  ■Because there might be false negative due to the presence of break-down substances like fibrinolysins
• ■Negative coagulase tests are confirmed after how many hours?

  
  

  ■At what temperature are the negative tests stored?

  ■Confirm results after 20hours

  ■Store negative results at 4`C
• What may be the cause of false positive in coagulase test?

  ■Citrate anticoagulant + Citrate utilizing organism = release of calcium

  
  

  ■ results to clot/clump formation
• Examples of Coagulase positive Staphylococcus spp. [4]

  ■S. aureus subsp. aureus

  ■S. intermedius

  ■S. hyicus

  ■S. scleiferi subsp. Coagulans
• What tests may be used to differentiate each?

  ■Tube coag.

  ■Vogues-Proskauer

  ■PYR test
• What is the result expected from Coag. Positive Staphylococcus spp.?

  ■S. aureus sbsp. aureus

  - Tube coag.: +

  - VP: +

  - PYR: -

  
  

  ■S. intermedius

  - Tube coag.: V

  - VP: -

  - PYR: +

  
  

  ■S. hyicus

  - Tube coag.: V

  - VP: -

  - PYR: -

  
  

  ■S. scleiferi sbsp. coagulans

  - Tube coag.: +

  - VP: +

  - PYR: +
• ■DNAse Test may be used to identify S. aureus, what other organisms can be identified by this test?(2)

  ■DNAase positive organisms

  ■Serratia

  ■Moraxella
• Contents of the DNAse media?

  ■ DNA Media

  ■ Methyl Green
• Positive result of DNAse test?

  clearing
• ■What is the action of protein A?

  
  

  ■What is its action on immunoglobulins?

  ■Inhibition of phagocytosis

  
  

  ■Naturally absorbs the Fc portion of Immunoglobulins
• Enzymes released by Staphylococcus aureus(5)

  Hint: HDL CS

  
  

  ■Hyaluronidase -spreading factor

  ■DNAase

  ■Lipase

  ■Coagulase - initiates clot formation

  ■Staphylokinase -fibrinolysin
• Toxins released by Staph. aureus (4)

  Hint: SHEL

  
  

  ■Staphyloenterotoxin/enterotoxin

  ■Hemolysins

  ■Exfoliatin

  ■Leukocidins
• ■What is the effect of exfoliative toxin?

  
  

  ■What is the effect of enterotoxins?

  ■Exfoliative toxin - Scalded skin syndrome/Ritter's disease

  
  

  ■Enterotoxin - Toxic shock syndrome
• Other name for leukocidins?

  Pantou-Valentin Factor
• ■This is the

  Streptococcus spp.classification that is based on antigenic group-specific cell wall polysaccharide.

  ■The pathogenic spp. ofStrep. belongs to what group in this classification?

  ■Lancefield classification

  ■Group A
• ■What is the common medically important Strep. spp. in Group B of the Lancefield classification?

  [aside fromS.pyogenes]

  ■This spp. is most commonly associated with what infections?■Streptococcus viridans (Manuel)

  ■ Streptococcus agalactiae (Mahon)

  ■Neonatal infections