Gram -ve bacteria
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Questions and Answers

What is the function of Phospholipase D in Chryseobacterium?

  • Resistance to human serum blood (correct)
  • Toxicity to epithelial cells
  • Biofilm formation
  • Iron acquisition

    • Chryseobacterium is a Gram-positive rod.

    False

    What is the function of DNase in Chryseobacterium?

    To break down DNA and assist in spreading the infection and evading immune defense

    Haemophilus influenzae is a type of _______________________ bacillus.

    <p>Pleomorphic small</p> Signup and view all the answers

    What is the function of Phosphatase in Chryseobacterium?

    <p>To remove phosphate groups from proteins</p> Signup and view all the answers

    Chryseobacterium is a strictly aerobic bacterium.

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

    Match the following bacteria with their characteristics:

    <p>Chryseobacterium = Gram-positive rod Haemophilus influenzae = Strictly aerobic</p> Signup and view all the answers

    What is the function of Protease in Chryseobacterium?

    <p>To break down proteins and damage tissues and evade the immune response</p> Signup and view all the answers

    What is quorum sensing in bacteria?

    <p>A way bacteria communicate with each other based on population density</p> Signup and view all the answers

    The human immune system always responds appropriately to infections.

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

    What is the name of the process by which Acinetobacter spp. extract iron from their environment?

    <p>Iron extraction</p> Signup and view all the answers

    Pseudomonas can cause _______________________ through the spread of infection through the bloodstream.

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

    Match the bacteria with the potential infection they can cause:

    <p>Pseudomonas = Sepsis Acinetobacter = Endocarditis or Meningitis</p> Signup and view all the answers

    Much is known about the pathogenicity and virulence factors of Pseudomonas and Acinetobacter.

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

    What does Haemophilus influenzae require for growth?

    <p>Both Factor X and Factor V</p> Signup and view all the answers

    Haemophilus influenzae can grow on blood agar without the presence of Staphylococcus aureus.

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

    What is the role of IgA1 protease in the virulence of Haemophilus influenzae?

    <p>evades mucosal resistance to infection by destroying IgA</p> Signup and view all the answers

    Haemophilus influenzae has _________ serotypes based on capsular antigens.

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

    Match the following virulence factors of Haemophilus influenzae with their functions:

    <p>Capsule = provides protection against phagocytosis Pili = adhesion to mucosal cells Exotoxins = evades mucosal resistance to infection</p> Signup and view all the answers

    What is the role of bacteriocin in the virulence of Haemophilus influenzae?

    <p>Competition with other bacteria</p> Signup and view all the answers

    What is the oxygen requirement of Pseudomonas aeruginosa?

    <p>Obligate aerobe</p> Signup and view all the answers

    Pseudomonas aeruginosa is a lactose fermenting bacterium.

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

    What is the function of the glycocalyx in Pseudomonas aeruginosa?

    <p>Adhesion and biofilm formation</p> Signup and view all the answers

    Pseudomonas aeruginosa has a distinct colony morphology that is often _______________________ on certain media.

    <p>bluish-green</p> Signup and view all the answers

    Match the following mechanisms of drug resistance in Pseudomonas aeruginosa:

    <p>Efflux Pumps = Pump antibiotics out of the cell Beta-lactamases = Degrade beta-lactam antibiotics Aminoglycoside-modifying enzymes = Inactivate aminoglycosides</p> Signup and view all the answers

    What is the function of biofilm formation in Pseudomonas aeruginosa?

    <p>To reduce antibiotic effectiveness</p> Signup and view all the answers

    What is the function of pili in Pseudomonas aeruginosa?

    <p>To aid adhesion to the host epithelial cell</p> Signup and view all the answers

    Endotoxin is a secreted toxin that causes lysis of host cells.

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

    What is the function of exotoxin A in Pseudomonas aeruginosa?

    <p>Lysis of host cells and inhibition of protein synthesis</p> Signup and view all the answers

    Pyocyanin is a _______________ pigment that generates reactive oxygen species.

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

    Which of the following infections is commonly associated with Pseudomonas aeruginosa?

    <p>Pneumonia in cystic fibrosis patients</p> Signup and view all the answers

    Leukocidin inhibits the function of neutrophils and lymphocytes.

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

    Match the following Pseudomonas aeruginosa toxins with their functions:

    <p>Exotoxin A = Lysis of host cells and inhibition of protein synthesis Phospholipase C = Destruction of cytoplasmic membrane of host cells Pyocyanin = Generation of reactive oxygen species Leukocidin = Inhibition of neutrophil and lymphocyte functions</p> Signup and view all the answers

    What is the role of elastase in Pseudomonas aeruginosa infections?

    <p>Plays a role in corneal infection</p> Signup and view all the answers

    What is the oxygen requirement of Acinetobacter?

    <p>Strictly aerobic</p> Signup and view all the answers

    Acinetobacter is a Gram-positive bacterium.

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

    What is the role of quorum sensing in bacteria?

    <p>Quorum sensing is a way bacteria communicate with each other based on their population density.</p> Signup and view all the answers

    Acinetobacter spp. can extract iron from their environment through a process called _______________.

    <p>iron extraction</p> Signup and view all the answers

    Match the following clinical significance of Acinetobacter with their descriptions:

    <p>Nosocomial infection = A type of infection acquired in a hospital Catheter-associated infection = An infection caused by a medical device Ventilator-associated infection = An infection caused by a medical device Wound/soft tissue infection = An infection of the skin or underlying tissue Endocarditis = An infection of the heart valves</p> Signup and view all the answers

    What is the characteristic of Acinetobacter spp. that helps them resist the immune system?

    <p>Resistance to serum and complements</p> Signup and view all the answers

    The human immune system always responds appropriately to infections.

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

    What is the characteristic of Chryseobacterium that helps them to be distinguished from other bacteria on blood agar?

    <p>The presence of a yellow pigment</p> Signup and view all the answers

    Chryseobacterium is a motile bacterium.

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

    What is the function of protease in Chryseobacterium?

    <p>Breakdown proteins to damage tissues and evade the immune response.</p> Signup and view all the answers

    Chryseobacterium is a type of _______________________ bacterium.

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

    Match the following enzymes with their functions in Chryseobacterium:

    <p>Phosphatase = Removes phosphate groups from proteins or other molecules (dephosphorylation) Kinase = Adds phosphate groups to proteins or other molecules (phosphorylation) Protease = Breaks down proteins to damage tissues and evade the immune response DNase = Breaks down DNA to assist in spreading the infection and evading immune defense</p> Signup and view all the answers

    What percentage of children aged 2-5 years are affected by encapsulated strains of Haemophilus influenzae

    <p>3-5%</p> Signup and view all the answers

    Individuals with spleen issues are at a higher risk of developing infections from unencapsulated strains of Haemophilus influenzae.

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

    What is the primary diagnosis method used to detect Haemophilus influenzae infections?

    <p>Sample Cultures (Blood, CSF, synovial fluid, pleural fluid, etc.)</p> Signup and view all the answers

    The 'thumbprint sign' is a characteristic finding in _______________________ caused by Haemophilus influenzae.

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

    What is the shape of Haemophilus influenzae?

    <p>Pleomorphic small bacilli (coccobacillus)</p> Signup and view all the answers

    Haemophilus influenzae is a motile bacterium.

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

    What are the growth requirements for Haemophilus influenzae?

    <p>Chocolate agar with Factor X (hemin) and Factor V (NAD)</p> Signup and view all the answers

    Haemophilus influenzae has _______________________ serotypes based on capsular antigens.

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

    Match the following Haemophilus influenzae virulence factors with their functions:

    <p>Bacteriocin/haemocin = fight off other bacteria for competition Pili = Adhesion to mucosal cells IgA1 protease = Destroying IgA; Evade mucosal resistance to infection Adhesins = adhesion to epithelial cells</p> Signup and view all the answers

    What is the transmission route of Haemophilus influenzae?

    <p>Respiratory droplets and secretions</p> Signup and view all the answers

    Haemophilus influenzae can grow on blood agar without the presence of Staphylococcus aureus.

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

    What is the role of IgA1 protease in the virulence of Haemophilus influenzae?

    <p>Evade mucosal resistance to infection by destroying IgA</p> Signup and view all the answers

    Study Notes

    Quorum Sensing

    • Bacteria communicate with each other based on population density, coordinating activities when enough are present.
    • This process involves adjusting gene expression in response to cell density, allowing bacteria to act collectively and enhance survival and virulence.

    Iron Acquisition

    • Acinetobacter spp. extract iron from the environment, crucial for growth and survival.
    • Iron extraction from host's body can cause damage to host cells.
    • They are highly resistant to serum and complements, components of the immune system.

    Environmental Survival

    • Bacteria survive in the environment by resisting drying out.
    • They are resistant to disinfectants and antibiotics via biofilm formation.

    Virulence Factors

    • Not much is known about the pathogenicity and virulence of Acinetobacter.
    • Pseudomonas is associated with sepsis, while Acinetobacter is associated with endocarditis and meningitis.

    Acinetobacter baumannii

    • OmpA: outer membrane protein.
    • Pili assembly/fimbria.
    • Biofilm-associated proteins.
    • Phospholipase D: resistant to human serum, evades epithelial cell defenses, and contributes to pathogenesis.
    • Phospholipase C: toxic to epithelial cells.

    Chryseobacterium

    • 125 species.
    • Gram-negative rods, non-motile, with yellow pigment on BA.
    • Strictly aerobic, oxidase-positive, and catalase-positive.

    Chryseobacterium Virulence Factors

    • Protease: breaks down proteins, damaging tissues and evading immune response.
    • DNase: breaks down DNA, spreading infection and evading immune defenses.
    • Phosphatase: regulates enzyme activity by removing phosphate groups.

    Haemophilus influenzae

    • Gram-negative, pleomorphic, small bacilli (coccobacillus).
    • Non-motile, non-spore former, facultative anaerobe.
    • Oxidase-positive, catalase variable.
    • Capsulated forms are called Type B (super virulent form).

    Haemophilus influenzae Growth Requirements

    • Cultivation medium: Chocolate agar, requires Factor X (hemin) and Factor V (NAD).
    • Alternative growth method: Blood agar with Staphylococcus aureus colonies providing Factor V via red blood cell haemolysis.

    Haemophilus influenzae Classification

    • Encapsulated strains: six serotypes based on capsular antigens (a, b, c, d, e, f).
    • Unencapsulated strains: non-typeable, lacking a polysaccharide capsule.

    Haemophilus influenzae Virulence Factors

    • Capsule: pentose sugar + ribitol-phosphate Endo.
    • Pili: adhesion to mucosal cells.
    • Exotoxins: IgA1 protease, evading mucosal resistance to infection.
    • Adhesins: adhesion to epithelial cells.
    • Exotoxins: bacteriocin (haemocin), helping to fight off other bacteria.

    Pseudomonas Aeruginosa Characteristics

    • Gram-negative rod bacterium
    • Obligate aerobe, meaning it requires oxygen for metabolism
    • Non-lactose fermenting and non-spore forming
    • Catalase, citrate, and oxidase positive
    • Encapsulated with a mucoid exopolysaccharide capsule
    • Possesses flagellum for motility and pili for adhesion
    • Multi-drug efflux pumps and various drug-resistance enzymes

    Colony Morphology

    • Spreading and flat with serrated edges, no smooth edge
    • Often shows metallic sheen, depending on the media
    • Bluish-green, red, or brown color, with a yellowy green color on nutrient agar (NA)

    Drug Resistance Mechanisms

    • Efflux pumps: pump antibiotics out of the cell
    • Beta-lactamases: degrade beta-lactam antibiotics
    • Aminoglycoside-modifying enzymes: inactivate aminoglycosides
    • Biofilm formation: encapsulation in mucoid layer, reducing antibiotic effectiveness

    Virulence Factors

    • Glycocalyx: produces mucoid substance, aiding adhesion and biofilm formation
    • Pili: surface protrusions aiding adhesion to host epithelial cells
    • Neuraminidase enzymes: facilitate pili binding
    • Endotoxin (LPS): part of cell wall, causing host cell damage and symptoms of sepsis
    • Exotoxin A: secreted toxin, inhibiting protein synthesis and causing host cell lysis
    • Other exotoxins: enterotoxin, exoenzyme S, phospholipase C, and leukocidin

    Infections and Symptoms

    • Common infections: blood, skin, urinary tract, eyes, bones, and ears
    • Symptoms: systemic (fever, elevated heart and respiratory rates, increased white blood cell count) and localized (specific to infection site)

    Diagnosis and Treatment

    • Diagnosis: complete blood count (CBC), cultures of site of infection
    • Treatment: not specified, but often involves antibiotic therapy and management of underlying conditions

    General Characteristics of Acinetobacter

    • Gram-negative, short bacilli in pairs
    • Non-motile, capsulated, and strictly aerobic
    • Oxidase-negative and catalase-positive

    Clinical Significance of Acinetobacter

    • Causes nosocomial infections, including catheter-associated, ventilator-associated, and wound/soft tissue infections
    • Associated with endocarditis and a significant threat in hospital settings
    • Can cause respiratory tract infections, including pneumonia, bacteraemia, and meningitis, as well as UTI

    Virulence Factors

    • Natural resistance to host response and ability to form biofilms
    • Quorum sensing allows for coordinated activities, gene expression regulation, and enhanced survival and virulence
    • Iron acquisition mechanisms enable extraction of iron from the environment, killing of host cells, and resistance to serum and complements

    Environment and Survival

    • Resistant to desiccation, disinfectants, and antibiotics due to biofilm formation

    Comparison with Pseudomonas

    • Acinetobacter is a concern for endocarditis and meningitis, while Pseudomonas is a concern for sepsis

    A. baumannii

    • Causes nosocomial infections of importance
    • Virulence factors include:
      • OmpA (outer membrane proteins)
      • Pili assembly/fimbria
      • Biofilm-associated proteins
      • Phospholipase D (resistance to human serum, epithelial cell evasion, and pathogenesis)
      • Phospholipase C (toxicity to epithelial cells)

    Chryseobacterium General Characteristics

    • Gram-negative rods
    • Non-motile bacteria
    • Produce a distinctive yellow pigment on blood agar (BA), similar to S. aureus
    • Strictly aerobic, requiring oxygen for growth
    • Oxidase positive, indicating the presence of cytochrome c oxidase
    • Catalase positive, allowing the breakdown of hydrogen peroxide

    Habitat and Distribution

    • Ubiquitous, found in a wide range of environments

    Virulence Factors

    • Protease: breaks down proteins, damaging tissues and evading the immune response
    • DNase: breaks down DNA, facilitating the spread of infection and evasion of immune defenses
    • Phosphatase: removes phosphate groups from molecules, regulating enzyme activity by turning them on or off
    • Interferes with the activity of other enzymes, including kinases, which add phosphate groups to proteins or molecules through phosphorylation

    Characteristics of Haemophilus influenzae

    • Gram-negative, pleomorphic, small bacilli (coccobacillus)
    • Non-motile and non-spore forming
    • Facultative anaerobe, oxidase +ve, catalase +ve
    • Encapsulated or non-encapsulated, with only capsulated forms being Type B (super virulent form)

    Growth Requirements

    • Chocolate agar with Factor X (hemin) and Factor V (NAD) for growth
    • Alternative growth method: Blood agar with Staphylococcus aureus colonies to provide Factor V
    • Haemophilus influenzae is a fastidious grower, requiring supplemented factors (X and V) for growth

    Classification

    • Encapsulated strains: six serotypes based on capsular antigens (a, b, c, d, e, f)
    • Unencapsulated strains: non-typeable, lacking a polysaccharide capsule

    Virulence Factors

    • Capsule: pentose sugar + ribitol-phosphate
    • Pili: adhesion to mucosal cells
    • Exotoxins: IgA1 protease, evading mucosal resistance to infection
    • Adhesins: adhesion to epithelial cells
    • Exotoxins: Bacteriocin (haemocin), fighting off other bacteria
    • Outer Membrane Proteins (OMPs): Endo
    • Lipooligosaccharides (LOS): Endo

    Diseases Caused by Haemophilus influenzae

    • Meningitis
    • Otitis media
    • Sinusitis
    • Epiglottitis
    • Pharyngitis and Laryngitis
    • Bacteraemia and Endocarditis
    • Cellulitis
    • Conjunctivitis
    • Haemophilus parainfluenzae: Endocarditis, Secondary bacteraemia, Urethritis

    Epidemiology

    • Transmission: Respiratory droplets and secretions
    • Colonisation rates:
      • Non-encapsulated strains: 40-80% of children and adults
      • Encapsulated strains: 3-5% of children aged 2-5 years
    • Risk factors:
      • Encapsulated strains: children, especially unvaccinated, individuals with spleen issues, people with malignancies or complement component deficiencies, those with acute viral infections
      • Unencapsulated strains: children and immunocompromised individuals, people with chronic lung conditions

    Diagnosis

    • Sample cultures: Blood, CSF, synovial fluid, pleural fluid, etc.
    • Serological methods: Latex agglutination, enzyme immunoassay, coagglutination
    • Specific tests:
      • Epiglottitis: Laryngoscopy, X-ray showing "thumbprint sign"
      • Bronchopneumonia: Chest X-ray showing ground-glass opacities, bronchial wall thickening, consolidation

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