Podcast
Questions and Answers
What is the main difference between Micrococcaceae and Streptococcaceae?
What is the main difference between Micrococcaceae and Streptococcaceae?
- Catalase positive vs. catalase negative
- Associated with human infections vs. not
- Produce coagulase vs. do not
- Arrangement in tetrads vs. pairs or chains (correct)
Which enzyme is responsible for the basis of the coagulase test?
Which enzyme is responsible for the basis of the coagulase test?
- Amylase
- Coagulase (correct)
- Catalase
- Protease
Which Staphylococcus species is considered the most pathogenic?
Which Staphylococcus species is considered the most pathogenic?
- S. aureus (correct)
- S. epidermidis
- S. schleiferi
- S. saprophyticus
What do non-coagulase producing Staphylococci species refer to as?
What do non-coagulase producing Staphylococci species refer to as?
Who named Staphylococcus and what does the name mean?
Who named Staphylococcus and what does the name mean?
Which of the following Staphylococcus species is most commonly associated with human infections?
Which of the following Staphylococcus species is most commonly associated with human infections?
What characteristic pigmentation led to the naming of the species Staphylococcus aureus by Rosenbach?
What characteristic pigmentation led to the naming of the species Staphylococcus aureus by Rosenbach?
Which of the following is NOT a feature of Staphylococcus aureus as mentioned in the text?
Which of the following is NOT a feature of Staphylococcus aureus as mentioned in the text?
Why is Staphylococcus aureus of importance as a human pathogen, especially in hospital environments?
Why is Staphylococcus aureus of importance as a human pathogen, especially in hospital environments?
Which factor is NOT associated with the cell wall of Staphylococcus aureus according to the text?
Which factor is NOT associated with the cell wall of Staphylococcus aureus according to the text?
What is the typical arrangement of Staphylococcus aureus cells?
What is the typical arrangement of Staphylococcus aureus cells?
Which type of infections can Staphylococcus aureus produce according to the text?
Which type of infections can Staphylococcus aureus produce according to the text?
Study Notes
Classification of Gram-Positive Cocci
- Gram-positive cocci are classified into two families: Micrococcaceae and Streptococcaceae, differentiated by the catalase test.
- Micrococcaceae includes genera Micrococcus and Staphylococcu.
- Staphylococcus species are arranged in clusters.
- Micrococcus species are skin commensals, usually not associated with human infections, and are arranged in tetrads.
Staphylococcus aureus
- Staphylococcus aureus is catalase positive, coagulase positive, facultative anaerobe, non-motile, non-sporing, and occasionally capsulated.
- It produces golden yellow pigmentation on blood agar and alpha-hemolytic colonies.
- S. aureus is the most pathogenic species and produces an enzyme coagulase, which forms the basis of coagulase test.
Virulence Factors of Staphylococcus aureus
- Cell wall-associated factors: peptidoglycan, teichoic acid, protein A, and clumping factor.
- Membrane active toxins: hemolysins, leukocidin (or Panton-Valentine toxin), epidermolytic toxin (exfoliative toxin), and toxic shock syndrome toxin.
- Extracellular enzymes: coagulase, deybonuclease, and heat-stable thermolysin.
Coagulase-Negative Staphylococci (CoNS)
- CoNS are rarely pathogenic to humans, but may cause infections in immunocompromised patients.
- Examples of CoNS include S. epidermidis, S. saprophyticus, S. lugdunensis, S. schleiferi, S. haemolyticus, and S. warneri.
History of Staphylococcus
- Staphylococcus was named after the Greek word "Staphyle" meaning "a bunch of grapes" and "kokkos" meaning "berry-shaped" by Sir Alexander Ogston in 1880.
- Rosenbach named the species S. aureus in 1884 based on the characteristic golden yellow pigmentation of its colonies.
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Description
Learn about Staphylococcal infections and the classification of gram-positive cocci into Micrococcaceae and Streptococcaceae families based on the catalase test. Explore the characteristics of Micrococcaceae and Streptococcaceae, including their arrangement and genera.
