Podcast
Questions and Answers
What is the primary role of δ hemolysin produced by S. aureus?
What is the primary role of δ hemolysin produced by S. aureus?
- To cause injury to cells and leukocytes (correct)
- To kill polymorphonuclear leukocytes
- To promote phagocytosis
- To facilitate the growth of bacteria
Furuncles are single lesions that do not progress into deeper tissues.
Furuncles are single lesions that do not progress into deeper tissues.
False (B)
What bacterium is often associated with community-acquired skin infections and is known for producing Panton-Valentine leukocidin?
What bacterium is often associated with community-acquired skin infections and is known for producing Panton-Valentine leukocidin?
S. aureus
A __________ is an infection of the hair follicle.
A __________ is an infection of the hair follicle.
Match the following S. aureus infections with their descriptions:
Match the following S. aureus infections with their descriptions:
Which toxins are associated with staphylococcal food poisoning?
Which toxins are associated with staphylococcal food poisoning?
Toxic shock syndrome toxin-1 (TSST-1) is produced by the phage group II.
Toxic shock syndrome toxin-1 (TSST-1) is produced by the phage group II.
What syndrome is caused by exfoliative toxin from S. aureus?
What syndrome is caused by exfoliative toxin from S. aureus?
The primary reservoir of S. aureus is the ______.
The primary reservoir of S. aureus is the ______.
What type of activity is enhanced by β hemolysin?
What type of activity is enhanced by β hemolysin?
Match the following toxins of S. aureus with their effects:
Match the following toxins of S. aureus with their effects:
Name one mode of transmission for S. aureus.
Name one mode of transmission for S. aureus.
The three main types of hemolysins are α, β, and ______.
The three main types of hemolysins are α, β, and ______.
What is the main effect of hyaluronidase in infections?
What is the main effect of hyaluronidase in infections?
Protein A negates the protective effects of immunoglobulin A (IgA).
Protein A negates the protective effects of immunoglobulin A (IgA).
What syndrome is associated with severe exfoliative dermatitis?
What syndrome is associated with severe exfoliative dermatitis?
The condition known as _________ is linked with the use of super-absorbent tampons.
The condition known as _________ is linked with the use of super-absorbent tampons.
Match the following enzymes with their functions:
Match the following enzymes with their functions:
What is a potential consequence of Toxic Shock Syndrome?
What is a potential consequence of Toxic Shock Syndrome?
What duration do symptoms of Staphylococcal scalded skin syndrome typically last?
What duration do symptoms of Staphylococcal scalded skin syndrome typically last?
Staphylococcus epidermidis is primarily responsible for community-acquired infections.
Staphylococcus epidermidis is primarily responsible for community-acquired infections.
Which of the following is a mode of transmission for Aureus?
Which of the following is a mode of transmission for Aureus?
Micrococcus luteus produces acid under anaerobic conditions in glucose O/F media.
Micrococcus luteus produces acid under anaerobic conditions in glucose O/F media.
What antibiotic is used to treat infections caused by Methicillin-resistant Staphylococci?
What antibiotic is used to treat infections caused by Methicillin-resistant Staphylococci?
Chronic infections, indwelling devices, and immune response defects are examples of __________ conditions that predispose individuals to Aureus infections.
Chronic infections, indwelling devices, and immune response defects are examples of __________ conditions that predispose individuals to Aureus infections.
Match the following types of MRSA with their characteristics:
Match the following types of MRSA with their characteristics:
Which method is recommended to determine methicillin resistance in staphylococci?
Which method is recommended to determine methicillin resistance in staphylococci?
Vancomycin-resistant Staphylococcus aureus (VRSA) was first isolated in the United States in 2007.
Vancomycin-resistant Staphylococcus aureus (VRSA) was first isolated in the United States in 2007.
What gene is associated with methicillin resistance in Staphylococcus aureus?
What gene is associated with methicillin resistance in Staphylococcus aureus?
The gold standard for identifying methicillin-resistant Staphylococcus aureus is the __________ test.
The gold standard for identifying methicillin-resistant Staphylococcus aureus is the __________ test.
Match the identification methods with their descriptions:
Match the identification methods with their descriptions:
Which of the following statements is true regarding macrolide resistance?
Which of the following statements is true regarding macrolide resistance?
Only a small fraction of the population of methicillin-resistant Staphylococcus aureus express the phenotype despite having the genetic potential.
Only a small fraction of the population of methicillin-resistant Staphylococcus aureus express the phenotype despite having the genetic potential.
What does the mecA gene encode?
What does the mecA gene encode?
Study Notes
Pus Formers
- Hot-cold lysin operates optimally at 37°C; effectiveness is maintained when stored at 4°C.
- Furuncle (boil): painful skin inflammation affecting the skin and subcutaneous tissue.
- Carbuncles: multiple localized lesions that may penetrate deeper tissues than a single boil.
Infections Caused by S. aureus
- Skin and wound infections include:
- Folliculitis: infection of the hair follicle.
- Bullous impetigo: large pustules with surrounding redness; highly contagious, spreading via direct contact and fomites.
Virulence Factors of S. aureus
- Exotoxins include enterotoxins causing diarrhea and vomiting; heat-stable, resistant to gastric acid.
- Toxic Shock Syndrome Toxin-1 (TSST-1) is a superantigen resulting in toxic shock syndrome.
- Exfoliative toxin (epidermolytic toxin): causes sloughing of the epidermal layer, linked to Scalded Skin Syndrome (SSS) and bullous impetigo.
- Hemolysins: three main types (α, β, δ); α hemolysin destroys platelets and tissues, while β hemolysin enhances activity against RBC membranes.
Enzymes in S. aureus
- Coagulase: diagnostic marker, unclear role in virulence.
- Hyaluronidase: hydrolyzes hyaluronic acid, facilitating the spread of infection.
- Lipase: breaks down fats and oils of sebaceous glands.
Protein A
- Binds to the Fc portion of antibodies, evading phagocytosis, and negating immunoglobulin G (IgG) protective effects.
Toxic Shock Syndrome
- Linked to super-absorbent tampons with symptoms including high fever, rash, watery diarrhea, and vomiting leading to dehydration and hypotension.
- Transmission via needle sticks, skin destruction, and medical procedures.
Epidemiology of S. aureus
- Primary reservoir: nasal passages (nares); other reservoirs include axillae, vagina, and skin surfaces.
- Hospital outbreaks frequently occur in nurseries, burn units, and among surgical patients.
- Transmitted through unwashed hands and fomites.
Scalded Skin Syndrome
- Extensive exfoliative dermatitis; more common in patients with renal failure and the immunocompromised.
- Severity varies, lasting 2 to 4 days, with a potential for spontaneous recovery in children, but adult cases may be fatal.
Methicillin-Resistant Staphylococci (MRSA)
- HACO-MRSA and HA-MRSA represent health care-associated and hospital-associated strains, respectively, posing significant health threats.
- Infection control measures include barrier protection, contact isolation, and handwashing.
- Treatment primarily involves vancomycin with susceptibility tested via cefoxitin.
Rapid Identification Methods
- BBL staphyloslide, Staphaurex®, and BactiStaph® are used for identifying MRSA.
- Real-time PCR and qualitative nucleic acid hybridization assays target staphylococcal identification from blood cultures.
- Gold standard: mecA gene detection via PCR for identifying MRSA.
Vancomycin-Resistant Staphylococci
- VRSA and VISA emerged in the U.S. in 2002, indicating increased antibiotic resistance challenges.
Macrolide Resistance
- Resistance patterns to clindamycin may not be immediately evident; erythromycin and clindamycin should show the same resistance patterns.
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Description
Test your knowledge on Staphylococcus aureus and its associated infections. This quiz covers δ hemolysin, community-acquired skin infections, and various types of lesions produced by this bacterium. Match infections with their descriptions to enhance your understanding of S. aureus pathology.
