Microbiology Quiz: Enterococcus
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Questions and Answers

What does an increased white blood cell count (leukocytosis) indicate?

  • An increase in likely infection or inflammation (correct)
  • An increase in maturity of neutrophils
  • A normal physiological condition
  • A decrease in immune response

    • Which subtype of white blood cells increases in response to viral infections?

  • Eosinophils
  • Neutrophils
  • Monocytes
  • Lymphocytes (correct)

    • What condition does bandemia (left shift) indicate in a patient's WBC differential?

  • A lack of inflammatory response
  • Recovery from a chronic infection
  • Immature neutrophils in response to infection (correct)
  • An increase in eosinophils

    • What does a normal Erythrocyte Sedimentation Rate (ESR) indicate?

    <p>No significant inflammatory response is occurring</p> Signup and view all the answers

    Which laboratory test is specifically used to determine in vitro susceptibility of microorganisms to antibiotics?

    <p>Susceptibility Testing</p> Signup and view all the answers

    In what scenario is monocytosis commonly observed?

    <p>Certain leukemias and specific bacterial infections</p> Signup and view all the answers

    What does the Clear ring or 'zone of inhibition' signify in the Kirby-Bauer method?

    <p>Susceptibility to the antibiotic tested</p> Signup and view all the answers

    Which of the following is true about eosinophilia?

    <p>It may indicate an allergic reaction or parasitic infection</p> Signup and view all the answers

    Which microorganism is a common cause of community-acquired pneumonia and meningitis?

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

    What is the mechanism behind methicillin resistance in Staphylococcus aureus?

    <p>Altered penicillin-binding protein</p> Signup and view all the answers

    Which of the following Streptococcus species is commonly associated with infective endocarditis?

    <p>Viridans group Streptococci</p> Signup and view all the answers

    Which strain of Enterococcus is associated with various infections, including UTIs and endocarditis?

    <p>Enterococcus faecalis</p> Signup and view all the answers

    Which type of hemolysis is produced by Streptococcus pyogenes?

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

    Which organism is more commonly found and generally easier to treat?

    <p>Enterococcus faecalis</p> Signup and view all the answers

    What is a characteristic of Clostridium species?

    <p>Anaerobic gram-positive bacilli</p> Signup and view all the answers

    Which Clostridium species is known to produce pseudomembranous colitis?

    <p>Clostridium difficile</p> Signup and view all the answers

    Which of the following is not an Enterobacteriaceae family member?

    <p>Pseudomonas aeruginosa</p> Signup and view all the answers

    What infection is commonly associated with Enterobacteriaceae?

    <p>Urinary tract infection (UTI)</p> Signup and view all the answers

    Which Enterococcus species is known for being less common and more difficult to treat?

    <p>Enterococcus faecium</p> Signup and view all the answers

    Which of the following statements correctly describes Pseudomonas aeruginosa?

    <p>Colonizes moist environments</p> Signup and view all the answers

    What is a major concern regarding Enterobacteriaceae in recent years?

    <p>Association with antimicrobial resistance</p> Signup and view all the answers

    What does MIC stand for in the context of antibiotic testing?

    <p>Minimum Inhibitory Concentration</p> Signup and view all the answers

    How is susceptibility determined according to CLSI and EUCAST?

    <p>Through the determination of MIC breakpoints</p> Signup and view all the answers

    What classification indicates that bacteria are resistant to an antibiotic?

    <p>Resistant (R)</p> Signup and view all the answers

    If an E.coli isolate has an MIC of 0.5 for ciprofloxacin, how would it be classified?

    <p>Intermediate (I)</p> Signup and view all the answers

    Which method uses laser desorption/ionization to identify pathogens?

    <p>MALDI-TOF</p> Signup and view all the answers

    What is the time frame in which susceptibility testing results are typically available?

    <p>72 hours</p> Signup and view all the answers

    What does an intermediate classification imply regarding antibiotic effectiveness?

    <p>Antibiotic may work with higher dosing or in specific situations</p> Signup and view all the answers

    Which of the following statements is true about MIC breakpoints?

    <p>They vary by bacterial species and antibiotic</p> Signup and view all the answers

    Which of the following is a common symptom of a urinary tract infection (UTI)?

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

    What is meant by the term 'empiric antimicrobial prescribing'?

    <p>Starting treatment with antibiotics without knowing the specific pathogen</p> Signup and view all the answers

    Which vital sign indicates hyperthermia?

    <p>Body temperature greater than 38 C</p> Signup and view all the answers

    What differentiates microbial infection from contamination?

    <p>Infection occurs when pathogens multiply and cause disease</p> Signup and view all the answers

    Which of the following is NOT a common imaging study used to diagnose infections?

    <p>Blood tests</p> Signup and view all the answers

    What clinical finding is associated with meningitis?

    <p>Nuchal rigidity</p> Signup and view all the answers

    Which symptom is commonly associated with pneumonia?

    <p>Shortness of breath</p> Signup and view all the answers

    Which feature is a common sign of skin/soft tissue infection?

    <p>Purulent discharge</p> Signup and view all the answers

    Study Notes

    Objectives of the Lecture

    • Ability to identify common diagnostic factors of infectious disease, including labs, symptoms, and imaging studies.
    • Understanding of pathogen identification and susceptibility testing application in case scenarios.
    • Distinction between microbial infection, contamination, and colonization.
    • Definitions of empiric, definitive, and prophylactic antimicrobial prescribing with case applications.
    • Knowledge application in antimicrobial prescribing principles to select appropriate cases.
    • Identification of significant features of select microorganisms.

    Signs and Symptoms of Infection

    • General Vital Signs:
      • Hyperthermia (> 38°C) and possible hypothermia (< 36°C).
      • Tachycardia (> 100 bpm) and tachypnea (> 20 rpm).
      • Hypotension (SBP < 100 mmHg).
    • General Symptoms: Headache, nausea/vomiting, fatigue, and myalgia.
    • Site-Specific Symptoms:
      • Meningitis: mental status changes, confusion, blurred vision, and stiff neck.
      • Sinus infection: runny nose, congestion, and dental pain.
      • Pneumonia: cough, shortness of breath, and chest pain.
      • GI infections: abdominal pain, diarrhea, and bloody stools.
      • UTI: dysuria, urgency, and hematuria.
      • Skin infections: redness, swelling, and purulent discharge.

    Imaging Studies

    • Primarily site-specific imaging used for diagnosis, including X-rays, CT scans, MRIs, ultrasounds, and echocardiograms.

    Laboratory Findings

    • Complete Blood Count (CBC):
      • White Blood Cell (WBC) count indicating leukocytosis (> 12,000 cells/mm³) or leukopenia (< 4,000 cells/mm³).
      • Differential providing percentages of WBC subtypes that may indicate specific conditions or infections.
    • Common WBC Responses:
      • Neutrophilia indicates infection; bandemia (increased immature neutrophils) suggests heightened infection levels.
      • Monocytosis may indicate certain infections and diseases; lymphocytosis is often viral; eosinophilia suggests parasitic infections.

    Additional Laboratory Findings

    • Erythrocyte Sedimentation Rate (ESR):
      • Normal ranges for males (0 to 20 mm/h) and females (0 to 30 mm/h); used as a non-specific inflammatory marker.
    • C-Reactive Protein:
      • Elevated levels indicate inflammation; important to monitor in infections.

    Susceptibility Testing

    • Determination of in vitro susceptibilities of microorganisms to antimicrobials through methods like Kirby-Bauer disk diffusion, showing zones of inhibition.
    • Minimum Inhibitory Concentration (MIC) testing identifies the lowest antibiotic concentration preventing bacterial growth.

    MIC Breakpoints

    • Published by CLSI & EUCAST to classify isolate-antibiotic pairs as susceptible, intermediate, or resistant.
      • Susceptible (S): Effective against the bacteria.
      • Intermediate (I): Limited effectiveness; may require higher doses.
      • Resistant (R): Not effective; alternative antibiotics needed.

    Culture Timeline

    • Steps of microbial culture from specimen collection to susceptibility testing results typically take 72 hours.

    Identification of Pathogens

    • MALDI-TOF: Rapid identification method for pathogens.
    • Antibody & Antigen Detection: Useful for specific infections.

    Key Microorganisms

    • MRSA: Methicillin-resistant Staphylococcus aureus characterized by altered penicillin-binding proteins.
    • Streptococcus:
      • Grouped by hemolytic properties (alpha, beta, gamma) with common infections including pneumonia and skin infections.
    • Enterococcus: Common gut flora; includes challenging bacteria like E. faecium, often resistant to treatments.
    • Clostridium: Anaerobic and spore-forming, including pathogens like C. difficile, known for causing serious gastrointestinal diseases.
    • Enterobacteriaceae: Important group of gram-negative rods, common in UTIs; relationships with antimicrobial resistance, notably ESBLs and CRE.
    • Pseudomonas aeruginosa: Multi-drug resistant organism associated with various nosocomial infections.

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    Description

    Test your knowledge on Enterococcus species, specifically Enterococcus faecalis and Enterococcus faecium. This quiz covers their prevalence, treatment challenges, and relevance in vancomycin-resistant Enterococci. Put your microbiology skills to the test!

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