Microbiology Quiz: Enterococcus

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?

No significant inflammatory response is occurring Signup and view all the answers

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

Susceptibility Testing Signup and view all the answers

In what scenario is monocytosis commonly observed?

Certain leukemias and specific bacterial infections Signup and view all the answers

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

Susceptibility to the antibiotic tested Signup and view all the answers

Which of the following is true about eosinophilia?

It may indicate an allergic reaction or parasitic infection Signup and view all the answers

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

Streptococcus pneumoniae Signup and view all the answers

What is the mechanism behind methicillin resistance in Staphylococcus aureus?

Altered penicillin-binding protein Signup and view all the answers

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

Viridans group Streptococci Signup and view all the answers

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

Enterococcus faecalis Signup and view all the answers

Which type of hemolysis is produced by Streptococcus pyogenes?

Beta hemolytic Signup and view all the answers

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

Enterococcus faecalis Signup and view all the answers

What is a characteristic of Clostridium species?

Anaerobic gram-positive bacilli Signup and view all the answers

Which Clostridium species is known to produce pseudomembranous colitis?

Clostridium difficile Signup and view all the answers

Which of the following is not an Enterobacteriaceae family member?

Pseudomonas aeruginosa Signup and view all the answers

What infection is commonly associated with Enterobacteriaceae?

Urinary tract infection (UTI) Signup and view all the answers

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

Enterococcus faecium Signup and view all the answers

Which of the following statements correctly describes Pseudomonas aeruginosa?

Colonizes moist environments Signup and view all the answers

What is a major concern regarding Enterobacteriaceae in recent years?

Association with antimicrobial resistance Signup and view all the answers

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

Minimum Inhibitory Concentration Signup and view all the answers

How is susceptibility determined according to CLSI and EUCAST?

Through the determination of MIC breakpoints Signup and view all the answers

What classification indicates that bacteria are resistant to an antibiotic?

Resistant (R) Signup and view all the answers

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

Intermediate (I) Signup and view all the answers

Which method uses laser desorption/ionization to identify pathogens?

MALDI-TOF Signup and view all the answers

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

72 hours Signup and view all the answers

What does an intermediate classification imply regarding antibiotic effectiveness?

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

Which of the following statements is true about MIC breakpoints?

They vary by bacterial species and antibiotic Signup and view all the answers

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

Dysuria Signup and view all the answers

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

Starting treatment with antibiotics without knowing the specific pathogen Signup and view all the answers

Which vital sign indicates hyperthermia?

Body temperature greater than 38 C Signup and view all the answers

What differentiates microbial infection from contamination?

Infection occurs when pathogens multiply and cause disease Signup and view all the answers

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

Blood tests Signup and view all the answers

What clinical finding is associated with meningitis?

Nuchal rigidity Signup and view all the answers

Which symptom is commonly associated with pneumonia?

Shortness of breath Signup and view all the answers

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

Purulent discharge 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!