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Questions and Answers
A lab technician observes Gram-negative cocci under a microscope. Further tests reveal the presence of oxidase. Which of the following organisms is most likely?
A lab technician observes Gram-negative cocci under a microscope. Further tests reveal the presence of oxidase. Which of the following organisms is most likely?
- Staphylococcus aureus
- Escherichia coli
- Streptococcus pneumoniae
- Neisseria gonorrhoeae (correct)
A patient presents with fever, stiff neck, and headache. A cerebrospinal fluid sample is taken and Gram staining reveals Gram-negative diplococci. Which virulence factor is most associated with the ability of Neisseria meningitidis to resist phagocytosis?
A patient presents with fever, stiff neck, and headache. A cerebrospinal fluid sample is taken and Gram staining reveals Gram-negative diplococci. Which virulence factor is most associated with the ability of Neisseria meningitidis to resist phagocytosis?
- Polysaccharide capsule (correct)
- IgA1 Protease
- Lipooligosaccharide (LOS)
- Pili
A microbiology student is learning about Neisseria gonorrhoeae. Which characteristic is NOT associated with N. gonorrhoeae?
A microbiology student is learning about Neisseria gonorrhoeae. Which characteristic is NOT associated with N. gonorrhoeae?
- Catalase-positive
- β-hemolytic (correct)
- Oxidase-positive
- Gram-negative
Neisseria meningitidis is able to invade the bloodstream and cause systemic infection. Which virulence factor enables Neisseria meningitidis to cross the blood-brain barrier, leading to meningitis?
Neisseria meningitidis is able to invade the bloodstream and cause systemic infection. Which virulence factor enables Neisseria meningitidis to cross the blood-brain barrier, leading to meningitis?
A 22-year-old male presents to the clinic with painful urination and purulent discharge. Gram staining of the discharge reveals Gram-negative diplococci within neutrophils. Which virulence factor is MOST likely contributing to the patient's symptoms?
A 22-year-old male presents to the clinic with painful urination and purulent discharge. Gram staining of the discharge reveals Gram-negative diplococci within neutrophils. Which virulence factor is MOST likely contributing to the patient's symptoms?
What is the PRIMARY function of IgA protease produced by both Neisseria gonorrhoeae and Neisseria meningitidis?
What is the PRIMARY function of IgA protease produced by both Neisseria gonorrhoeae and Neisseria meningitidis?
A researcher is studying the twitching motility of Neisseria gonorrhoeae. Which structure is directly responsible for this type of movement?
A researcher is studying the twitching motility of Neisseria gonorrhoeae. Which structure is directly responsible for this type of movement?
A young child is diagnosed with Waterhouse-Friderichsen syndrome. Which of the following organisms is the MOST likely causative agent?
A young child is diagnosed with Waterhouse-Friderichsen syndrome. Which of the following organisms is the MOST likely causative agent?
Which virulence factor of Neisseria meningitidis is specifically targeted by vaccines to prevent meningitis?
Which virulence factor of Neisseria meningitidis is specifically targeted by vaccines to prevent meningitis?
A patient is diagnosed with gonorrhea and prescribed penicillin. However, the infection does not respond to the treatment. What is the MOST likely reason for the treatment failure?
A patient is diagnosed with gonorrhea and prescribed penicillin. However, the infection does not respond to the treatment. What is the MOST likely reason for the treatment failure?
A microbiologist is performing a test to differentiate between Neisseria gonorrhoeae and Neisseria meningitidis. Which of the following tests would be MOST useful to distinguish between these two species?
A microbiologist is performing a test to differentiate between Neisseria gonorrhoeae and Neisseria meningitidis. Which of the following tests would be MOST useful to distinguish between these two species?
What role do opacity proteins (Opa) play in the pathogenesis of Neisseria gonorrhoeae?
What role do opacity proteins (Opa) play in the pathogenesis of Neisseria gonorrhoeae?
A newborn develops ophthalmia neonatorum. Which organism is MOST likely to be the causative agent?
A newborn develops ophthalmia neonatorum. Which organism is MOST likely to be the causative agent?
A patient presents with disseminated gonococcal infection (DGI). Which symptom is MOST commonly associated with DGI?
A patient presents with disseminated gonococcal infection (DGI). Which symptom is MOST commonly associated with DGI?
A clinician suspects a patient has Neisseria meningitidis meningitis. What is the MOST appropriate initial treatment?
A clinician suspects a patient has Neisseria meningitidis meningitis. What is the MOST appropriate initial treatment?
Which component of the Gram-negative cell wall is responsible for the endotoxic effects observed in Neisseria infections?
Which component of the Gram-negative cell wall is responsible for the endotoxic effects observed in Neisseria infections?
What is the clinical significance of Factor H binding protein (FHBP) in Neisseria meningitidis?
What is the clinical significance of Factor H binding protein (FHBP) in Neisseria meningitidis?
A microbiologist isolates Gram-negative cocci from a patient's cerebrospinal fluid. The isolate grows on both blood agar and chocolate agar. This suggests that the organism is MORE likely to be which of the following?
A microbiologist isolates Gram-negative cocci from a patient's cerebrospinal fluid. The isolate grows on both blood agar and chocolate agar. This suggests that the organism is MORE likely to be which of the following?
In the context of Neisseria gonorrhoeae infections, what is the primary role of porin proteins (Por)?
In the context of Neisseria gonorrhoeae infections, what is the primary role of porin proteins (Por)?
What is the MOST common reservoir for Neisseria gonorrhoeae in the population?
What is the MOST common reservoir for Neisseria gonorrhoeae in the population?
Which of the following is a unique characteristic of Neisseria meningitidis that distinguishes it from Neisseria gonorrhoeae?
Which of the following is a unique characteristic of Neisseria meningitidis that distinguishes it from Neisseria gonorrhoeae?
A patient with suspected meningitis undergoes a lumbar puncture. The Gram stain shows Gram-negative diplococci. What is the next MOST important step for rapid identification?
A patient with suspected meningitis undergoes a lumbar puncture. The Gram stain shows Gram-negative diplococci. What is the next MOST important step for rapid identification?
What is the mechanism of action of azithromycin, which is often used in conjunction with ceftriaxone to treat gonorrhea?
What is the mechanism of action of azithromycin, which is often used in conjunction with ceftriaxone to treat gonorrhea?
What is a key consideration when managing a patient presenting with signs and symptoms suggestive of Neisseria meningitidis infection?
What is a key consideration when managing a patient presenting with signs and symptoms suggestive of Neisseria meningitidis infection?
Flashcards
Gram-Negative Cocci
Gram-Negative Cocci
Gram-negative bacteria with a spherical or oval shape.
Oxidase test
Oxidase test
A biochemical test to detect the presence of cytochrome c oxidase.
Maltose Fermentation Test
Maltose Fermentation Test
A test to determine if a microbe can ferment maltose as a carbon source, indicated by a color change from red to yellow.
IgA Protease
IgA Protease
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Gonorrhea
Gonorrhea
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Gonococcemia
Gonococcemia
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Lipooligosaccharide (LOS)
Lipooligosaccharide (LOS)
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Opacity Proteins (Opa)
Opacity Proteins (Opa)
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Porin Proteins (Por)
Porin Proteins (Por)
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Airborne droplets
Airborne droplets
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Meningococcemia
Meningococcemia
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Meningitis
Meningitis
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Brudzinski Sign
Brudzinski Sign
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N. meningitidis Capsule
N. meningitidis Capsule
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Factor H binding protein
Factor H binding protein
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Opthalmia neonatorum
Opthalmia neonatorum
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Diplococci
Diplococci
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Catalase
Catalase
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Chocolate Agar
Chocolate Agar
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Ceftriaxone
Ceftriaxone
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Twitching Motility
Twitching Motility
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Study Notes
- Gram-negative cocci includes Neisseria
- They are paired, oxidase-positive, and catalase-positive
- They display twitching motility
Class Objectives
- To compare, describe & contrast Gram+ cocci with Gram- cocci
- To use diagnostic/laboratory tests, to discriminate cultures of bacteria
- To describe virulence factors & explain their function in subverting the immune system, making the host sick, or increasing spread
- To diagnose and treat the diseases caused
Gram-Negative Bacteria
- Diplococci can be aerobic:
- N. gonorrhoeae does not utilizes maltose
- N. meningitidis utilizes maltose
Neisseria
- Diplococci bacteria that under a microscope look like coffee beans
- Aerobic, but can be facultatively intracellular
- Catalase+ to reduce hydrogen peroxide
- Oxidase+
- Motile, non-spore forming
- Only Neisseria gonorrhoeae & Neisseria meningitidis are pathogenic to humans
Oxidase Test & Maltose Utilization
- Oxidase tests for the presence of cytochrome C oxidase
- Oxidase is an enzyme that promotes the transfer of a hydrogen atom from a substrate to oxygen, forming water or hydrogen peroxide
- A positive test consists of a color change from red to yellow, indicating a pH change to acidic
- Maltose Fermentation tests for the microbe’s ability to ferment the carbohydrate (sugar) maltose
- If maltose is fermented to produce acid end products, the pH of the medium will drop
- A pH indicator in the medium changes color
Neisseria Meningitidis
- Known as "Meningococcus"
- Pathogenic serogroups include A, B, C, Y, W-135
- Airborne droplets adhere to the pharynx and enter the bloodstream
- Those with complement deficiencies are at greater risk
- Meningitis develops most often in ages 2-18:
- Characterized by inflammation of the meninges
- Presents with fever, stiff neck, and headache
- Meningococcemia occurs with or without meningitis:
- Presents with fever, headache, nausea/vomiting
- Presents with pain in Musculoskeletal system
- Petechiae may indicates purpura then gangrene
- Waterhouse-Friderichsen Syndrome can happen
- characterized by adrenal gland hemorrhage, thrombosis, and organ damage
- Pneumonia can affect older adults
- Prevention is through vaccination
- Treatment involves Cephalosporin or Penicillin G
Neisseria Gonorrhoeae
- Known as "Gonococcus"
- Can grow on Chocolate Agar
- Sexually transmitted via genital, rectal, and pharyngeal routes
- Gonorrhea
- Asymptomatic carriers are key reservoirs
- In males:
- Urethra discharge
- Epididymitis
- Prostatitis,
- Periurethral abscesses
- In females:
- Often appears asymptomatic
- Presents with discharge, pain, and bleeding
- Can lead to PID, Uterine tube infections, Ectopic pregnancy, and Infertility
- Gonococcemia
- Presents with fever
- Presents with chills
- Presents with skin pustules
- Presents with Septic arthritis
- Opthalmia Neonatorum:
- Infection acquired in birth canal
- Treated with Erythromycin ointment
- Prevention involves intramuscular ceftriaxone
- It can be treated with oral azithromycin
Virulence Factors: N. meningitidis & N. gonorrhoeae
- Lipooligosaccharide (LOS): endotoxin with toxic lipid A region
- Pili: attaches to host cell, facilitates twitching motility to escape
- IgA Protease: degrades IgA to allow bacteria to reach mucous membranes in the respiratory and genital tracts
- Outer membrane proteins includes
- Opacity proteins (Opa): binds epithelial and phagocytic cells
- Strains appear opaque if they have Opa
- Porin proteins (Por): creates pores to allow nutrient and waste movement and allow bacteria to live intracellularly
- PorA- N. meningitidis
- PorB- N. meningitidis & N. gonorrhoeae
- Opacity proteins (Opa): binds epithelial and phagocytic cells
Virulence Factors: N. meningitidis
- Capsule inhibits phagocytosis
- Factor H binding protein (FHBP) inhibits complement pathway
Virulence Factors: N. gonorrhoeae
- β-lactamase causes penicillin resistance
Jane Hinton, DVM (1919-2003)
- She studied at the University of Pennsylvania
- She was one of the first two African-American women to earn a DVM
- Her father Dr. William Augustus Hinton opened the first "Medical Laboratory Techniques" courses open to women
- Jane co-developed Mueller-Hinton agar used to isolate Neisseria bacteria
- Mueller-Hinton agar is the gold standard for antibiotic testing
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