Bacteria Quiz: Streptococcus pyogenes & H. influenzae
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Questions and Answers

What is the mechanism of action for ampicillin and amoxicillin?

  • Inhibition of DNA synthesis
  • Disruption of protein synthesis
  • Targeting the cell wall (correct)
  • Blocking metabolic pathways

    • What causes an increase in lymphocyte numbers in the blood?

  • Phagocytes absorbing lymphocytes
  • Increased production of lymphocyte precursors
  • Lymphocytes entering lymphoid tissue
  • Inhibition of signal transduction by chemokine receptors (correct)

    • Which enzyme synthesized and exported by organisms can inhibit phagocyte bactericidal activity?

  • Nitric oxide synthase
  • Peptidoglycan synthase
  • ADP-ribosylase
  • Adenylate cyclase (correct)

    • What method is considered the gold standard for diagnosing classical pertussis disease?

    <p>Culture of the pathogen</p> Signup and view all the answers

    Which phase of pertussis is characterized by the classical whooping cough?

    <p>Paroxysmal phase</p> Signup and view all the answers

    What is the mainstay of treatment for patients with active pertussis infection?

    <p>Supportive therapy</p> Signup and view all the answers

    Which of the following treatments is considered effective for patients with pertussis?

    <p>Macrolide antibiotics</p> Signup and view all the answers

    What effect does tracheal cytotoxin have on the respiratory tract?

    <p>Damages ciliated epithelial cells</p> Signup and view all the answers

    What type of bacteria is Corynebacterium diphtheriae classified as?

    <p>Gram-positive rod</p> Signup and view all the answers

    What is a major adverse effect associated with phenobarbital?

    <p>Over sedation</p> Signup and view all the answers

    How do barbiturates affect CYP enzymes?

    <p>They induce the enzymes.</p> Signup and view all the answers

    Ceftriaxone is particularly useful for treating which condition?

    <p>H. influenzae meningitis</p> Signup and view all the answers

    What is a consequence of CYP induction by barbiturates?

    <p>Dispositional tolerance.</p> Signup and view all the answers

    Why is ceftriaxone not effective against certain infections?

    <p>It is ineffective against enterococcal infections.</p> Signup and view all the answers

    What method of administration is used for ceftriaxone?

    <p>Intravenous infusion</p> Signup and view all the answers

    What happens when the dose of phenobarbital is increased?

    <p>Patient experiences sedation.</p> Signup and view all the answers

    Which of the following statements about ceftriaxone is true?

    <p>It can cross the blood-brain barrier.</p> Signup and view all the answers

    What is one of the virulence factors of Streptococcus pyogenes that aids in pathogen spread?

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

    Which of the following diseases is NOT caused by Streptococcus pyogenes?

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

    What is the primary method of prophylaxis to prevent acute rheumatic fever following an infection with Streptococcus pyogenes?

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

    What feature of H.influenzae helps it resist phagocytosis in a nonimmune host?

    <p>Polysaccharide capsule</p> Signup and view all the answers

    Which of the following encapsulated serotypes of H.influenzae is most commonly associated with serious illnesses like meningitis?

    <p>Type b</p> Signup and view all the answers

    After an infection with Streptococcus pyogenes, what is the typical onset time for complications such as Post-Streptococcal Glomerulonephritis?

    <p>1-3 weeks</p> Signup and view all the answers

    Which factor contributes to the invasiveness of H.influenzae strains?

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

    Which of the following antibiotics is commonly prescribed for infections caused by Streptococcus pyogenes due to limited antibiotic resistance?

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

    How is diphtheria primarily transmitted?

    <p>Via droplets and aerosols from coughing</p> Signup and view all the answers

    What is the characteristic manifestation of diphtheria in patients?

    <p>Upper respiratory tract infection with pharyngitis</p> Signup and view all the answers

    What is the primary method for diagnosing diphtheria?

    <p>Throat swab culture and observation of the pseudomembrane</p> Signup and view all the answers

    What critical complication can arise from diphtheria due to airway obstruction?

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

    Which treatment is effective for diphtheria infections but does not affect the preformed toxin?

    <p>Penicillin and erythromycin</p> Signup and view all the answers

    What type of vaccine is commonly used to immunize children against diphtheria?

    <p>Combination toxoid vaccine DTaP</p> Signup and view all the answers

    What is produced in the throat as a result of the diphtheria toxin's action?

    <p>A grayish exudate known as pseudomembrane</p> Signup and view all the answers

    What organism is known to cause diphtheria?

    <p>Corynebacterium diphtheriae</p> Signup and view all the answers

    Which organism is most commonly associated with causing pneumonia in infants and children?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    What is the primary mechanism by which phenobarbital is excreted unchanged?

    <p>Alkaline urine pH</p> Signup and view all the answers

    Which of the following is a high-risk group for pneumonia?

    <p>Elderly individuals with chronic lung disease</p> Signup and view all the answers

    What type of genetic regulation involves the repression of the lac operon?

    <p>Negative control</p> Signup and view all the answers

    Pneumocystis jirovecii is primarily associated with which group of patients?

    <p>Immunocompromised individuals</p> Signup and view all the answers

    What common clinical manifestation might indicate pneumonia in elderly patients?

    <p>Confusion or altered mental status</p> Signup and view all the answers

    Which of the following organisms is associated with atypical pneumonia?

    <p>Mycoplasma pneumoniae</p> Signup and view all the answers

    What is a significant pharmacological effect of phenobarbital?

    <p>CNS depressant</p> Signup and view all the answers

    Study Notes

    Streptococcus pyogenes

    • Microbiological features: Gram-positive coccus, often in chains. Bacteria of the pharynx (throat)
    • Virulence factors:
      • Hyaluronidase, collagenase, and streptokinase: Damage mucosal membranes. Streptokinase dissolves blood clots, aiding spread.
      • Streptolysins: Destroy red and white blood cells.
      • M-protein: Involved in rheumatic heart disease.
    • Diseases: Pharyngitis (sore throat), scarlet fever, skin infections.
    • Sequelae (complications): Acute rheumatic fever (1-3 weeks after infection) and post-streptococcal glomerulonephritis (PSGN): both with specific time frames and mechanisms.
    • Treatment: Primarily 6-lactams (e.g., penicillin); oral amoxicillin is common.
    • Prophylaxis: Penicillin to prevent acute rheumatic fever

    H. influenzae

    • Microbiological features: Gram-negative coccobacillus (rod-like). Facultative anaerobe (lives with oxygen or without oxygen).
    • Virulence factors: Polysaccharide capsule resists phagocytosis and complement. Six encapsulated types (a-f) with type B most often causing meningitis, epiglottitis.
    • Treatment: Empirically, 3rd-generation cephalosporins are used.
    • Diagnosis: Requires culturing on chocolate agar and requiring factor X (hemin) and V (NAD+).
    • Resistance: Beta-lactamase; reduces effectiveness of beta-lactam antibiotics.

    Bordetella Pertussis

    • Characteristics: Gram-negative, aerobic, pathogenic, encapsulated coccobacillus
    • Virulence factors:
      • Attachment to cilia via FHA (Filamentous hemagglutinin)
      • Pertussis toxin, stimulating adenylate cyclase, causing respiratory mucosa edema and a severe cough. Inhibits signal transduction in lymphocytes reducing cellular entry.
      • Tracheal cytotoxin damaging ciliated cells and working with endotoxin causing cell death.
    • Disease: Whooping Cough
    • Stages: Catarrhal, paroxysmal, convalescence.
    • Diagnosis: Culture, PCR, DFA, serology
    • Treatment: Supportive care (oxygen, breathing treatments)

    Corynebacterium diphtheriae

    • Characteristics: Club-shaped, Gram-positive rod.
    • Transmission: Droplets and aerosols (coughing)
    • Pathogenesis: Diphtheria toxin blocks protein synthesis, resulting in respiratory epithelial cell death, pseudomembrane formation, and airway obstruction.
    • Diseases: Nasopharyngeal and cutaneous infections.
    • Diagnosis: Presumptive diagnosis with pseudomembrane. Laboratory culture (swabs) and PCR to detect toxin.
    • Treatment: Penicillin or erythromycin and antitoxin (preformed antibodies).

    General Information on Pneumonia

    • Definitions: CAP (community-acquired pneumonia), HAP (hospital-acquired pneumonia), VAP (ventilator-associated pneumonia)
    • Typical/Atypical organisms: Details vary based on infection source and patients demographics.
    • Aspiration Pneumonia: Diverse types based on location and material.
    • Modes of Infections: Direct transmission or the spread of infection from elsewhere through the body.
    • High-risk groups: Details vary
    • Organisms: Emphasis on organisms causing pneumonia such as Streptococcus pneumoniae, Klebsiella pneumoniae, Staphylococcus aureus, Mycoplasma pneumoniae, Legionella pneumophila, and Pneumocystis jirovecii. Diagnostic features and treatment and prevention strategies for these organisms and how they cause different types of pneumonia are included.

    Other Topics

    • Phenobarbital: CNS depressant, metabolized by CYP enzymes. Used as an anticonvulsant.
    • Ceftriaxone: 3rd-generation cephalosporin, potent against many bacteria. Works by interfering with the formation of bacterial cell walls. Usefulness in treating meningitis.
    • Penicillin and Amoxicillin: Penicillin is antibacterial drug targeting the peptidoglycan cell walls of bacteria. With different strengths, amoxicillin is more common in today's practice.

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    Week 5 Microbiology Summary PDF

    Description

    Test your knowledge of Streptococcus pyogenes and H. influenzae, focusing on their microbiological features, virulence factors, diseases, and treatment options. This quiz will cover key concepts regarding both bacteria and their clinical significance.

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