BACTE - WEEK 8 (PAMATAY)
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Questions and Answers

Which of the following is true about vancomycin-resistant Staphylococcus aureus (VRSA)?

  • VRSA is resistant to erythromycin
  • VRSA is derived from enterococci
  • VRSA has a MIC greater than or equal to 16 mg/mL (correct)
  • VRSA is susceptible to teicoplanin

    • Which of the following is true about vancomycin-intermediate susceptible Staphylococcus aureus (VISAs)?

  • VISAs are resistant to erythromycin
  • VISAs are resistant to teicoplanin (correct)
  • VISAs have a MIC of 4-8 pg/mL
  • VISAs are derived from enterococci

    • Which of the following is true about coagulase-negative staphylococci (CoNS)?

  • CoNS are contaminants and have limited pathogenicity (correct)
  • CoNS are resistant to novobiocin
  • CoNS cause bloodstream infections
  • CoNS are identified to the species level

    • Which of the following is true about Staphylococcus saprophyticus?

    <p>S. saprophyticus causes urinary tract infections in sexually active young women</p> Signup and view all the answers

    Which of the following is true about Staphylococcus epidermidis?

    <p>S. epidermidis is identified by initial colony counts</p> Signup and view all the answers

    Which of the following is true about Staphylococcus lugdunensis?

    <p>S. lugdunensis causes brain abscess and meningitis</p> Signup and view all the answers

    What is the purpose of the PYR disc test?

    <p>To identify Staphylococcus saprophyticus</p> Signup and view all the answers

    What is the result of a positive PYR broth test?

    <p>Brilliant red-fuchsia color</p> Signup and view all the answers

    What is the purpose of the Ornithine decarboxylase test?

    <p>To identify Staphylococcus aureus</p> Signup and view all the answers

    What is the result of a positive Voges-Proskauer test?

    <p>Red color</p> Signup and view all the answers

    Which of the following is NOT a symptom of Staphylococcal Scalded Skin Syndrome?

    <p>Infection of the hair follicle/oil glands</p> Signup and view all the answers

    What is the primary mechanism of Methicillin-Resistant Staphylococcus Aureus (MRSA)?

    <p>Production of altered penicillin-binding protein</p> Signup and view all the answers

    What is the function of the MRSA Screening Agar?

    <p>Differentiate between resistant and susceptible strains of MRSA</p> Signup and view all the answers

    What is the purpose of the CEFINASE test?

    <p>Detect β-lactamase production</p> Signup and view all the answers

    What is the procedure for the DNASE test?

    <p>Inoculate DNase agar with the test organism and incubate at 35-37°C for 13-24 hours</p> Signup and view all the answers

    What is the purpose of the Double Disk Diffusion/D Zone Test?

    <p>Detect inducible clindamycin resistance</p> Signup and view all the answers

    What is the purpose of the Latex Agglutination Test?

    <p>Detect clumping factor and protein A</p> Signup and view all the answers

    What is the temperature range for incubating Rabbit plasma?

    <p>35-37 degrees Celsius</p> Signup and view all the answers

    What is the incubation time for the DNASE test?

    <p>13-24 hours</p> Signup and view all the answers

    What is the function of the Chromagar?

    <p>Detect resistance of Staphylococcus aureus and Staphylococcus lugdunensis</p> Signup and view all the answers

    Which agar is resistant to drying, heat (50C for 30 mins), and 10% NaCl?

    <p>MSA - Mannitol salt agar</p> Signup and view all the answers

    Which agar is used to detect the presence of coagulase in Staphylococcus bacteria?

    <p>BAP - Blood agar plate</p> Signup and view all the answers

    Which agar is incubated at 35C in a CO2 incubator, or in a candle jar if no incubator is available to produce CO2?

    <p>CAP MAC THIO</p> Signup and view all the answers

    What is the alternative method for incubating media if no CO2 incubator is available?

    <p>CANDLE JAR</p> Signup and view all the answers

    Which agar allows the growth of a wide variety of organisms?

    <p>Blood CS bottles</p> Signup and view all the answers

    What is the function of Protein A in Staphylococcus bacteria?

    <p>Bound to cytoplasmic membrane; high affinity for the FC receptor on lgG molecules, and complement</p> Signup and view all the answers

    What is the procedure for the slide coagulase test?

    <p>Bacterial colony + rabbit plasma</p> Signup and view all the answers

    What is the function of Alpha toxin in Staphylococcus bacteria?

    <p>Disrupts smooth muscle in blood vessels &amp; toxic to RBCs, WBCs, hepatocytes, platelets, macrophages</p> Signup and view all the answers

    What is the function of Beta toxins in Staphylococcus bacteria?

    <p>Hydrolysis of membrane phospholipids (cell lysis)</p> Signup and view all the answers

    What is the function of Delta toxin in Staphylococcus bacteria?

    <p>Nonspecific membrane toxicity to other mammalian cells (cytolytic to erythrocytes)</p> Signup and view all the answers

    Which of the following toxins disrupts smooth muscle in blood vessels and is toxic to RBCs, WBCs, hepatocytes, platelets, and macrophages?

    <p>Alpha toxin</p> Signup and view all the answers

    Which of the following toxins is responsible for hydrolysis of membrane phospholipids and cell lysis?

    <p>Beta toxins</p> Signup and view all the answers

    Which of the following toxins is cytolytic to erythrocytes and exhibits nonspecific membrane toxicity to other mammalian cells?

    <p>Delta toxin</p> Signup and view all the answers

    Which of the following toxins is produced by all strains of Staphylococcus bacteria and works in association with Panton-Valentine Leukocidin (PVL)?

    <p>Gamma toxin</p> Signup and view all the answers

    Which of the following toxins is toxic to white blood cells and works in conjunction with gamma toxin to cause lysis?

    <p>Panton-Valentine Leukocidin (PVL)</p> Signup and view all the answers

    Which of the following toxins allows proliferation of white blood cells, T-cell receptors, and antigen-presenting cells, causing a cytokine storm?

    <p>Superantigens</p> Signup and view all the answers

    Which of the following toxins is heat-stable and resists boiling for 20 minutes?

    <p>Exfoliative Toxin A</p> Signup and view all the answers

    Which of the following toxins is plasmid-mediated and heat-labile?

    <p>Exfoliative Toxin B</p> Signup and view all the answers

    Which of the following toxins is also known as Pyrogenic Exotoxin C and is associated with toxic shock syndrome?

    <p>Toxic Shock Syndrome Toxin-1 (TSST-1)</p> Signup and view all the answers

    Which of the following toxins inhibits phagocytosis and works in conjunction with gamma toxin to cause lysis?

    <p>Panton-Valentine Leukocidin (PVL)</p> Signup and view all the answers

    Which test is used to detect the presence of catalase in a bacterial colony?

    <p>Catalase Test</p> Signup and view all the answers

    Which enzyme is responsible for the hydrolysis of lipids in plasma and skin, leading to the initiation of skin infections?

    <p>Lipase</p> Signup and view all the answers

    Which test is used to directly detect the presence of plasma fibrinogen and IgG in a bacterial sample?

    <p>Latex Agglutination Test</p> Signup and view all the answers

    Which test is used to detect the degradation of DNA by the test organism?

    <p>DNase Test</p> Signup and view all the answers

    Which test is used as a negative control in the Slide Coagulase Test?

    <p>Bacterial colony + sterile saline/water</p> Signup and view all the answers

    Which test is used to detect the presence of fibrin clot and enable the spread of infection?

    <p>Fibrinolysin</p> Signup and view all the answers

    Which test is used to detect the presence of hyaluronic acid hydrolysis and promote the spread of infection?

    <p>Hyaluronidase</p> Signup and view all the answers

    Which test is used to detect the presence of clot formation in a bacterial sample?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    Which test is used to check for slower coagulase production in a bacterial sample?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    Which test is used to inoculate DNase agar with the test organism?

    <p>DNase Test</p> Signup and view all the answers

    Which test is used to detect the presence of fibrin clot and enable the spread of infection?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    Which enzyme is responsible for the hydrolysis of lipids in plasma and skin, leading to the initiation of skin infections?

    <p>Lipase</p> Signup and view all the answers

    What is the function of Delta toxin in Staphylococcus bacteria?

    <p>Hydrolysis of lipids</p> Signup and view all the answers

    What is the result of a positive PYR broth test?

    <p>Presence of agglutination</p> Signup and view all the answers

    Which test is used to directly detect the presence of plasma fibrinogen and IgG in a bacterial sample?

    <p>Latex Agglutination Test</p> Signup and view all the answers

    Which of the following toxins is responsible for hydrolysis of membrane phospholipids and cell lysis?

    <p>Alpha toxins</p> Signup and view all the answers

    What is the temperature range for incubating Rabbit plasma?

    <p>35-37 degrees celsius</p> Signup and view all the answers

    Which test is used to detect the presence of clot formation in a bacterial sample?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    Which of the following toxins is heat-stable and resists boiling for 20 minutes?

    <p>Gamma toxins</p> Signup and view all the answers

    Which test is used to check for slower coagulase production in a bacterial sample?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    Which of the following toxins is highly immunogenic and leads to aggregation of the bacteria?

    <p>Clumping factor (A&amp;B)</p> Signup and view all the answers

    Which test is used to detect the presence of coagulase in Staphylococcus bacteria?

    <p>Slide Coagulase Test</p> Signup and view all the answers

    Which of the following toxins is responsible for hydrolysis of membrane phospholipids and cell lysis?

    <p>Beta toxins</p> Signup and view all the answers

    Which of the following toxins allows proliferation of white blood cells, T-cell receptors, and antigen-presenting cells, causing a cytokine storm?

    <p>Superantigens</p> Signup and view all the answers

    What is the purpose of the Latex Agglutination Test?

    <p>To detect the presence of plasma fibrinogen and IgG in a bacterial sample</p> Signup and view all the answers

    Which of the following is true about Staphylococcus lugdunensis?

    <p>It could produce clumping factor or coagulase</p> Signup and view all the answers

    Which test is used to detect the presence of fibrin clot and enable the spread of infection?

    <p>Tube Coagulase Test</p> Signup and view all the answers

    What is the function of Alpha toxin in Staphylococcus bacteria?

    <p>Disrupts smooth muscle in blood vessels</p> Signup and view all the answers

    Which of the following toxins is plasmid-mediated and heat-labile?

    <p>Exfoliative Toxin B</p> Signup and view all the answers

    Which agar is used to detect the presence of hyaluronic acid hydrolysis and promote the spread of infection?

    <p>DNASE Agar</p> Signup and view all the answers

    Which test is used to detect inducible clindamycin resistance in erythromycin-resistant strains of S. aureus?

    <p>Double Disk Diffusion/D Zone Test</p> Signup and view all the answers

    What is the MIC value for Vancomycin-Resistant Staphylococcus Aureus (VRSA)?

    <p>Greater than 16 mg/mL</p> Signup and view all the answers

    Which of the following is a characteristic of S. aureus in blood agar and CNA?

    <p>Medium to large, raised colonies with cream to golden yellow pigmentation</p> Signup and view all the answers

    Which of the following is a characteristic of S. aureus in bound coagulase?

    <p>Positive for coagulase production</p> Signup and view all the answers

    Which of the following is a characteristic of S. aureus in free coagulase?

    <p>Positive for coagulase production</p> Signup and view all the answers

    Which of the following is a characteristic of S. aureus in DNase?

    <p>Positive for DNase production</p> Signup and view all the answers

    Which of the following is a characteristic of S. aureus in thermostable nuclease?

    <p>Positive for thermostable nuclease production</p> Signup and view all the answers

    Which of the following CoNS species is isolated from humans?

    <p>S. epidermidis</p> Signup and view all the answers

    Which test is used to detect the presence of catalase in a bacterial colony?

    <p>Catalase Test</p> Signup and view all the answers

    Which test is used to detect the presence of coagulase in Staphylococcus bacteria?

    <p>Coagulase Test</p> Signup and view all the answers

    Which of the following is a symptom of folliculitis?

    <p>Red lump that becomes more painful as it fills with pus</p> Signup and view all the answers

    What is the result of a positive DNase test?

    <p>Release of methyl green and colorless area around the test organism</p> Signup and view all the answers

    What is the function of ß-lactamase (Penicillinase)?

    <p>Hydrolysis and inactivation of the ß-lactam ring</p> Signup and view all the answers

    What is the purpose of the MRSA Screening Agar?

    <p>Differentiates between two populations of Staphylococcus aureus (resistant or susceptible)</p> Signup and view all the answers

    What is the purpose of the CEFINASE test?

    <p>Qualitative test to detect β-lactamase production</p> Signup and view all the answers

    What is the function of MecC genes?

    <p>Encode for the expression of penicillin binding protein (PBP2A)</p> Signup and view all the answers

    What is the function of Protein A in Staphylococcus bacteria?

    <p>Inhibit phagocytosis and bind to Fc portion of IgG antibodies</p> Signup and view all the answers

    What is the purpose of the Chromagar?

    <p>Detect hyaluronic acid hydrolysis and promote the spread of infection</p> Signup and view all the answers

    What is the purpose of the CEFOTOXIN DISK DIFFUSION TEST?

    <p>Detection for resistance of Staphylococcus aureus and Staphylococcus lugdunensis</p> Signup and view all the answers

    What is the result of a positive CEFINASE test?

    <p>Deep pink color</p> Signup and view all the answers

    Study Notes

    Vancomycin-Resistant Staphylococcus aureus (VRSA)

    • VRSA shows resistance to vancomycin, a critical antibiotic, complicating treatment options.
    • Infections typically originate from methicillin-resistant Staphylococcus aureus (MRSA) strains.

    Vancomycin-Intermediate Susceptible Staphylococcus aureus (VISA)

    • VISA strains are partially resistant to vancomycin, showing reduced susceptibility, posing similar treatment challenges.

    Coagulase-Negative Staphylococci (CoNS)

    • CoNS are part of normal skin flora but can cause opportunistic infections, particularly in immunocompromised individuals.
    • Staphylococcus epidermidis, a common CoNS, is often implicated in nosocomial infections.

    Staphylococcus saprophyticus

    • Known for causing urinary tract infections, particularly in young sexually active women.
    • It exhibits unique resistance to novobiocin, distinguishing it from other staphylococci.

    Staphylococcus epidermidis

    • Frequently associated with infections from indwelling medical devices due to biofilm formation.
    • It is one of the most common CoNS and a significant pathogen in hospital settings.

    Staphylococcus lugdunensis

    • More pathogenic than many other CoNS; known for causing skin and soft tissue infections.
    • Distinct from other CoNS due to its ability to produce coagulase.

    PYR Disc Test

    • Tests for the enzymatic activity of L-pyrrolidonyl arylamidase, helping identify certain streptococci and enterococci.
    • A positive result indicates the presence of the enzyme.

    Pyogenic Broth Test

    • A positive result indicates the presence of certain bacteria capable of hydrolyzing L-pyrrolidonyl residues.

    Ornithine Decarboxylase Test

    • Identifies bacteria based on their ability to decarboxylate ornithine, serving as a differential test in enterobacteria.

    Voges-Proskauer Test

    • A positive result indicates the production of acetoin, linking to carbohydrate fermentation pathways.

    Staphylococcal Scalded Skin Syndrome Symptoms

    • Symptoms do not include fever; rare occurrence in adults and infection primarily impacts children.

    Mechanism of MRSA

    • MRSA primarily relies on the mecA gene conferring resistance to beta-lactam antibiotics.

    MRSA Screening Agar

    • This medium isolates and identifies MRSA from clinical samples by inhibiting non-MRSA species.

    CEFINASE Test

    • Detects the presence of beta-lactamase enzymes, crucial for determining antibiotic resistance in bacteria.

    DNASE Test Procedure

    • Involves inoculating DNase agar; a clear halo indicates DNase activity, confirming presence.

    Double Disk Diffusion/D Zone Test

    • Assesses antibiotic susceptibility or resistance through circular diffusion patterns of antibiotics.

    Latex Agglutination Test

    • Utilized for rapid identification of specific bacterial antigens in clinical samples.

    Rabbit Plasma Incubation

    • Typical incubation occurs at 35-37°C, facilitating coagulation tests.

    DNASE Test Incubation Time

    • Typically incubated for 24 hours.

    Chromagar Function

    • Selective growth medium that differentiates species based on colony color, aiding in identification.

    Resilient Agar Types

    • Staphylococcus growth media, such as Mannitol Salt Agar, resists drying, heat, and high salt concentrations.

    Coagulase Detection Agar

    • Used to identify coagulase production, vital for distinguishing Staphylococcus aureus from other species.

    Incubation in CO2 Environments

    • Bacterial cultures may be incubated in candle jars to create CO2-rich conditions.

    Alternative Incubation Methods

    • Candle jars can substitute for CO2 incubators when not available.

    Nutrient-Rich Growth Media

    • Certain agars support a wide variety of microorganisms, facilitating diverse culture growth.

    Protein A Function

    • A immunogenic surface protein in Staphylococcus that binds antibodies, evading immune response.

    Slide Coagulase Test Procedure

    • Involves mixing bacteria with plasma; agglutination indicates coagulase production.

    Alpha Toxin Function

    • Disrupts cell membranes, playing a pivotal role in causing tissue damage during infections.

    Beta Toxins Function

    • Toxins hydrolyze phospholipids, contributing to cytolytic activity against host cells.

    Delta Toxin Function

    • Known for cytolytic activity, particularly damaging to erythrocytes and membranes.

    Toxic Effects of Staphylococcus Toxins

    • Certain toxins disrupt smooth muscle and endothelium, damaging multiple cell types.

    Holistic Mechanism of Staphylococcus Toxins

    • Some toxins are linked with causing cytokine storms, amplifying immune response and inflammation.

    Heat-Stable Toxins

    • Specific toxins maintain stability against boiling, enhancing pathogenicity during infections.

    Plasmid-Mediated Toxins

    • Toxins that have a heat-labile nature may result in various immunogenic responses.

    Pyrogenic Exotoxin C

    • Associated with toxic shock syndrome, a critical virulence factor in Staphylococcus aureus.

    Catalase Detection Test

    • Identifies the enzyme catalase, which converts hydrogen peroxide into water and oxygen.

    Lipid Hydrolysis Enzyme Role

    • Specific enzymes, like lipases, are crucial for initiating skin infections by breaking down fats.

    Fibrinogen and IgG Detection Test

    • Tests for the presence of these proteins, indicating systemic infection or pathogen presence.

    DNase Test for DNA Degradation

    • Measures the ability of bacteria to hydrolyze DNA, informing pathogenic capabilities.

    Slide Coagulase Test Controls

    • Water or saline acts as a negative control to validate test specificity.

    Clot Formation Detection

    • Identifies staphylococcal strains' ability to promote fibrin clot formation, which enhances infection spread.

    Hyaluronic Acid Hydrolysis Test

    • Assesses bacterial capabilities to degrade hyaluronic acid, promoting tissue permeability and infection spread.

    Coagulase Production Checking Test

    • Differentiates between fast and slow coagulase producers, aiding in bacterial classification.

    DNase Agar Inoculation Test

    • Test organisms are inoculated onto DNase agar to check for deoxyribonuclease activity.

    Erythromycin-Induced Clindamycin Resistance Test

    • Detects inducible resistance linked to previous antibiotic exposure, guiding treatment choices.

    MIC Value for VRSA

    • A larger MIC value signifies higher resistance to vancomycin, complicating treatment strategies.

    Staphylococcus aureus Characteristics in Blood Agar

    • Produces beta-hemolysis, indicating complete lysis of red blood cells.

    Characteristics of Staphylococcus in Coagulase Tests

    • Bound coagulase indicates clumping factor presence; free coagulase confirms further pathogenic potential.

    DNase Test Result

    • A positive test is indicated by a clear zone around colonies on DNase agar.

    Beta-Lactamase Function

    • The enzyme acts to hydrolyze beta-lactam antibiotics, contributing to resistance in bacterial strains.

    CEFINASE Test Use

    • Rapid identification of beta-lactamase production aids in determining antibiotic sensitivity.

    MecC Gene Function

    • Provides an alternative mechanism for methicillin resistance, especially in certain Staphylococcus strains.

    Chromagar Purpose

    • Differentiates between species based on colony morphology and pigment production for easier identification.

    CEFOTOXIN Disk Diffusion Test

    • Tests for susceptibility of bacteria to specific cephalosporins, informing treatment regimens.

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    Description

    Test your knowledge of Mannitol Salt Agar (MSA) with this quiz! Learn about the characteristics of MSA, including its role in identifying halophiles and its ability to detect hemolysis. Discover how MSA can be used to differentiate between different types of bacteria based on colony color and halo formation. Challenge yourself with questions about incubation times and resistance to drying and heat.

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