Staphylococcus Question And Answers

Staphylococcus Important Notes

1. Toxins produced by staphylococci and diseases caused by them

2. Classification of streptococci

• Alpha hemolytic streptococci
• Beta hemolytic streptococci
• Gamma hemolytic/ non hemolytic/ enterococcus group

3. Toxins produced by streptococci

4. Diseases caused by streptococci

• Sore throat
• Ludwig’s angina, otitis media, quinsy, cellulitis
• Erysipelas, impetigo
• Acute glomerulonephritis
• Acute rheumatic fever

5. Toxins produced by pneumococci

• Hemolysin
• Leucocidin

6. Outer membrane of gonococci consists of

• Lipopolysaccharides
• Proteins
  • Protein 1 – helps in typing of strains, forms pores on surface
  • Protein 2 – helps in adhesion
  • Protein 3 – associated with protein 1

Read And Learn More: Microbiology Question and Answers

7. McLeod classification

• Gravis
• Intermedius
• Mitis

8. Test used for bacillus anthrax

• M Fadyean’s reaction
• String of pearls reaction
• Ascolis thermoprecipitation test

9. Diseases caused by bacillus anthrax

• Hide Porter’s disease
• Pulmonary anthrax
• Malignant pustule

10. Toxins produced by clostridium tetani

• Tetanolysin
• Tetanospasmin

11. Antigens of salmonella typhi

• H antigen
• O or somatic antigen
• Vi or virulence antigen

12. Types of E.coli

• Enteropathogenic E.coli
• Enterotoxigenic E.coli
• Entero aggregative E.coli
• Enteninvasive E.coli
• Enterohaemorrhagic E.coli

13. Classification of vibrios

• Halophilic vibrios
• V. vulnibicus
• V. alginolyticus
• V. parahemolyticus
• Non halophilic vibrios
• V. cholera
• V. mimicus

14. Diseases caused by Pseudomonas aeruginosa

• Infections in burns
• Iatrogenic meningitis
• Nosocomial infection
• Blue pus
• Bed sores
• Shanghai fever

15. Tests used for mycobacterium tuberculosis

• Catalase peroxidase
• Microscopy
• Petroff s method
• Montouxtest

16. Classification of leprosy

• Lepromatous leprosy
• Tuberculoid leprosy
• Dimorphous leprosy
• Indeterminate
• Pure neuritic

17. Lepra reaction

• Type 1 – reversal reaction
• Type 2 – erythema nodosum leprosum

Staphylococcus Long Essays

Question 1. Describe the morphology, staining characters, and pathogenicity of Staphylococcus. Add a note on laboratory diagnosis of staphylococcal infections.
Answer:

Staphylococcus Morphology:

• Staphylococcus are
  • Gram-positive
  • Non-motile
  • Non-sporing.
  • Non-capsulated
  • Aerobic and normally facultative anaerobic.
• Shape: spherical cocci.
• Size: approx 1 micrometer in diameter.
• Arrangement: Arranged in grape-like clusters.
• This arrangement is due to cell division occurring in three planes.
• They may be found singly, in pairs, and in short chains of 3 – 4 cells.

Staphylococcus Staining characters:

• Staphylococci are gram-positive cocci.
• On gram-staining:
  • They resist decolorization with acetone.
  • Retain the color of the primary stain.
  • Appears violet in color in pink background.

Staphylococcus Pathogenicity:

Staphylococcus produces two types of diseases.

1. Infections – In it.

2. Intoxications.

In it, the disease is caused by the toxins produced by bacteria.

Staphylococcal diseases:

Laboratory Diagnosis:

The specimen to be collected depends on the type of lesion.

Specimen

• Pus
• Sputum
• CSF
• Blood
• Suspected food

Infections

• Suppurative lesions
• Respiratory infections
• Meningitis
• Septicaemia
• Food poisoning

1. Direct microscopy.

• Gram staining of the smear shows gram-positive cocci arranged in clusters.

2. Culture.

• The inoculated media used are incubated at 37oC for 18 – 24 hours.
• The cultural media used are.

3. Biochemical reaction

• Catalase test – positive.
  • It distinguishes Staphylococcus from streptococcus
• Coagulase test – positive
• Mannitol fermentation – produces acid without gas
• Gelatin fermentation – positive.
• Tellurite reduction – positive.
• Production of enzyme phosphatase and deoxyribonuclease – positive.

4. Bacteriophage typing.

• Trace the source of staphylococcus.

5. Antibiotic susceptibility.

• Determined by Stokes method.

6. Serological tests.

• Helps to diagnose hidden deep infections.
• Also, titre more than 2 units/ml with rising titre diagnose deep infections.

Question 2. Classify staphylococci. Describe the morphology, cultural characteristics, and reactions of staphylococcus aureus. Describe the pathological lesions caused by staphylococci.
Answer:

Staphylococci Classification:

• Based on pigment production and virulence.

• Based on coagulase production.
• Coagulase positive – St. Aureus.
• Coagulase-negative – other staphylococci

Morphology Cultural characteristics:

Staphylococci usually grow readily within a temperature range of 10 – 42°C with an optimal temperature of 37°C and pH 7.4 – 7.6.

Morphology Reactions:

Staphylococcus aureus undergoes following, reaction.

• Catalase positive.
• Oxidase negative.
• Fermentation of sugar.
  • It ferments sugar without gas.
  • This helps to distinguish staphylococcus aureus from. St. Epidermidis.
• Causes beta type of hemolysis.
•  Produces.
  • Coagulase.
  • Phosphatase.
  • Enzyme deoxyribonuclease.
• Reduction of tellurite occurs.

Staphylococcus Short Essays

Question 1. Name enzymes produced by staphylococcus aureus.
Answer:

Enzymes:

Staphylococcus Short Question And Answers

Question 1. Antigenic structure of staphylococci.
Answer:

Antigenic structure of staphylococci composed on.

Question 2. Coagulase test.
Answer:

The coagulase test is the standard criterion for the identification of staphylococcus aureus isolates.

It is done by two methods.

1. Slide coagulase test.

• It detects bound coagulase.
• It gives results parallel to the tube test.
• In this method, a few colonies of bacteria re emulsified in a drop of normal saline on a clean glass slide.
• It is mixed with a drop of undiluted rabbit or human plasma.

2. Tube coagulase.

• It detects free coagulase.
• In this method, 0.1 ml of an overnight broth culture or an agar culture suspension of the organism is mixed with 0.5 ml of a 1 in 5 dilutions of human or rabbit plasma.
• Diluted plasma in another tube is used as a control.
• Plasma clots in case of positive reaction.

Question 3. Bacteriophage typing.
Answer:

• Bacteriophage typing is important in epidemiological studies of staphylococcal infections.
• Strains of S. aureus may be distinguished by their susceptibility to different bacteriophages.
• An internationally accepted set of 23 bacteriophages is employed.

Bacteriophage typing Method

Centre in India:

Department of Microbiology, Moulana Azad Medical College, New Delhi.

Question 4. Enumerate pyogenic organisms.
Answer:

Pyogenic Organism:

1. Staphylococcus Aureus – Gram-positive cocci.
2. Streptococcus pyogenes – Gram-positive cocci.
3. Klebsiella pneumonia – Gram-negative bacilli.
4. Burkholderia mallei – Gram-negative bacilli.

Question 5. Treatment of staphylococcal infections.
Answer: