Pathogens: Prions, Viruses, and Bacteria

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Questions and Answers

What is the primary characteristic of prion proteins (PrPsc)?

They accumulate in the brain and are associated with neurodegenerative diseases. (correct)

They contain a DNA/RNA core.

They have a protein coat called capsid.

They possess a lipid membrane envelope.

Which Gram staining characteristic distinguishes Gram-positive bacteria?

Thin cell wall.

Two phospholipid layers.

Thick cell wall with one phospholipid layer. (correct)

Presence of a lipid membrane.

Which type of fungi is most prevalent and often associated with opportunistic infections?

Aspergillus

Candida (correct)

Histoplasmosis

Mucor

What type of diagnostic techniques uses hematoxylin and eosin staining?

Histological examination. Signup and view all the answers

Which organism is classified under protozoa and is known to cause malaria?

Plasmodium Signup and view all the answers

Which route is NOT a common entry point for microbes into the body?

Contact with surfaces Signup and view all the answers

What distinguishes Gram-negative bacteria from Gram-positive bacteria based on cell wall structure?

They have a thin cell wall and two phospholipid layers. Signup and view all the answers

Which emerging infectious disease is caused by the severe acute respiratory syndrome coronavirus 2?

COVID-19 disease. Signup and view all the answers

What is the role of pili in bacteria?

To facilitate adherence to surfaces Signup and view all the answers

Which type of bacterial toxins is characterized by being components of the bacterial cell?

Endotoxins Signup and view all the answers

Which mechanism does NOT contribute to immune evasion in bacteria?

Production of antibodies Signup and view all the answers

How do some bacteria resist innate immunity?

By modifying their lipopolysaccharides Signup and view all the answers

Which of the following describes a direct tissue damage caused by immunity?

Destruction of tissues by immune cells Signup and view all the answers

Which route of entry is primarily associated with insect or animal bites?

Transmission Signup and view all the answers

What type of bacteria is known to cause destruction of the mucosa in the gastrointestinal tract?

Shigella Signup and view all the answers

Which of the following mechanisms allows for the entry of protozoa into enterocytes?

Attachment to brush border Signup and view all the answers

What is the primary effect of binding and tropism in viral injury mechanisms?

Reproductive cycle initiation Signup and view all the answers

What is a common characteristic of nosocomial infections?

They are associated with healthcare environments. Signup and view all the answers

In which stage of infection mechanisms do toxins lead to tissue damage?

Tissue damage activation Signup and view all the answers

What type of immune response occurs after exposure to a microbe?

Adaptive immunity Signup and view all the answers

What is the primary mechanism by which H. influenzae affects the respiratory system?

Impairment of ciliary activity Signup and view all the answers

What is a significant complication associated with viral hemorrhagic fevers?

Thrombocytopenia or severe platelet dysfunction Signup and view all the answers

Which virus primarily causes gingivostomatitis?

Herpes Simplex Virus type 1 Signup and view all the answers

Which of the following statements is true regarding Cytomegalovirus (CMV) infection?

It can be transmitted through various routes, including saliva and breast milk. Signup and view all the answers

What feature characterizes the lesions caused by Herpes Simplex Virus (HSV)?

Large pink to purple intranuclear inclusions Signup and view all the answers

What condition is associated with the reactivation of Varicella-Zoster Virus (VZV)?

Shingles Signup and view all the answers

Which of the following is NOT a complication of Cytomegalovirus infection in immunocompromised individuals?

Gingivostomatitis Signup and view all the answers

Which of the following is a primary mode of transmission for Hepatitis B Virus?

Percutaneous injury (IV drug use) Signup and view all the answers

Which of the following clinical presentations is associated with Herpes Simplex Virus type 2 (HSV2)?

Genital herpes Signup and view all the answers

What is the primary transmission method for Epstein-Barr Virus (EBV)?

Saliva Signup and view all the answers

Which of the following conditions is associated with Epstein-Barr Virus?

Infectious mononucleosis Signup and view all the answers

Which bacteria is known for causing skin infections and has virulence factors that include surface proteins and secreted enzymes?

Staphylococcus aureus Signup and view all the answers

What type of bacteria is responsible for diphtheria?

Gram-positive rods Signup and view all the answers

What is a characteristic of Methicillin-resistant Staphylococcus aureus (MRSA)?

It is resistant to all forms of penicillin. Signup and view all the answers

Which of the following pathogens is associated with the condition known as whooping cough?

Bordetella pertussis Signup and view all the answers

What is a common post-infectious syndrome associated with Streptococcus infection?

Rheumatic fever Signup and view all the answers

Which of the following bacteria are classified as Gram-negative rods?

Klebsiella granulomatis Signup and view all the answers

Wat type micro-organismen worden gezien in het infiltraat in de lymfklier bij de diagnose die wordt gesteld?

Macrofagen met intra-cytoplasmatische micro-organismen Signup and view all the answers

Welke aandoening is geassocieerd met Mycobacterium avium bij HIV-patiënten?

Atypische mycobacteriële infectie Signup and view all the answers

Wat is de gouden standaard voor de diagnose van tuberculose?

Cultures van sputum met 10.000 organismen Signup and view all the answers

Welke symptomen zijn kenmerkend voor secundaire tuberculose?

Malaise, anorexia en nachtelijk zweten Signup and view all the answers

Welke van de volgende aandoeningen wordt veroorzaakt door Mycobacterium leprae?

Huid- en zenuwaandoeningen Signup and view all the answers

Welke ziekte wordt veroorzaakt door prionen?

Creutzfeld-Jacob ziekte Signup and view all the answers

Wat is een kenmerk van virussen in termen van hun levensstijl?

Ze zijn obligate intracecellulaire organismen. Signup and view all the answers

Welke van de volgende microben is zowel facultatief als obligaat intracecellulair?

Mycobacterium tuberculosis Signup and view all the answers

Welk type microbe, volgens zijn levensstijl, leeft voornamelijk extracellulair?

Protozoa Signup and view all the answers

Wat onderscheidt facultatief intraceellulaire organismen van obligate intraceellulaire organismen?

Ze kunnen zowel binnen als buiten cellen overleven. Signup and view all the answers

Welke ziekte is verbonden aan de parasiet Leishmania donovani?

Kala-azar Signup and view all the answers

Welk type schimmel wordt vaak geassocieerd met opportunistische infecties?

Candida albicans Signup and view all the answers

Welke categorie van infectieuze agentia omvat voornamelijk wormparasieten?

Helminthen Signup and view all the answers

Wat is een mogelijke complicatie van een herhaalde leverbeschadiging door hepatitis-infecties?

Levercirrose Signup and view all the answers

Welke ziekte veroorzaakt Epstein-Barr Virus (EBV)?

Infectieuze mononucleosis Signup and view all the answers

Welke van de volgende bacteriën is grampositief en kan huidinfecties veroorzaken?

Staphylococcus aureus Signup and view all the answers

Wat is een kenmerk van Streptococcus infecties?

Kan leiden tot reumatische koorts Signup and view all the answers

Wat is een belangrijke virulentiefactor van Staphylococcus aureus?

Productie van enzymen die eiwitten afbreken Signup and view all the answers

Wat kenmerkt de infectie veroorzaakt door Neisseria gonorrhoeae?

Het kan leiden tot bacteriële meningitis Signup and view all the answers

Wat is een voornaamste transmissiemethode voor het Epstein-Barr Virus (EBV)?

Via speeksel Signup and view all the answers

Wat voor soort bacteriën zijn Bacillus anthracis en Corynebacterium diphtheriae?

Gram-positieve staven Signup and view all the answers

Welke van de volgende bacteriën is verantwoordelijk voor de ziekte van tuberculose?

Mycobacterium tuberculosis Signup and view all the answers

Wat is een veelvoorkomend post-infectie syndroom geassocieerd met infecties door Streptococcus soorten?

Glomerulonefritis Signup and view all the answers

Wat is een belangrijke eigenschap van prionen?

Ze zijn eiwitten die zich abnormaal ophopen. Signup and view all the answers

Wat typeert Gram-positieve bacteriën in vergelijking met Gram-negatieve bacteriën?

Ze bezitten een dikke celwand. Signup and view all the answers

Welk type schimmel is het meest verantwoordelijk voor opportunistische infecties?

Candida. Signup and view all the answers

Welk type protozoa is geassocieerd met de ziekte malaria?

Plasmodium. Signup and view all the answers

Welk van de volgende is een goed voorbeeld van een opportunistische schimmel?

Candida. Signup and view all the answers

Wat zijn de belangrijkste routes waardoor microben het lichaam binnendringen?

Alle genoemde routes. Signup and view all the answers

Wat beschrijft het best het verschil tussen aerobe en anaërobe bacteriën?

Anaërobe bacteriën groeien alleen in zuurstofarme omgevingen. Signup and view all the answers

Welke ziekte wordt veroorzaakt door het door SARS-CoV-2 veroorzaakte virus?

COVID-19. Signup and view all the answers

Welke organismen worden geclassificeerd als helminthen?

Rondwormen en lintwormen. Signup and view all the answers

Wat is een belangrijk diagnostisch hulpmiddel voor het detecteren van bepaalde infecties?

PCR. Signup and view all the answers

Wat is een voorbeeld van een exo-toxine dat door bacteriën wordt geproduceerd?

Hyaluronidase Signup and view all the answers

Welke van de volgende mechanismen wordt gebruikt door bacteriën voor immuunontwijking?

Antigeenvariatie Signup and view all the answers

Wat is een typisch effect van superantigenen geproduceerd door bacteriën?

Stimuleren van niet-specifieke T-celactivatie Signup and view all the answers

Welke aandoening is geassocieerd met kruisreactie door immuniteit?

Rheumatische hartziekte Signup and view all the answers

Wat doet de dichte capsule van bacteriën?

Maakt het moeilijker om door het immuunsysteem herkend te worden Signup and view all the answers

Waarom kunnen sommige bacteriën zich repliceren in fagocyten?

Ze ontsnappen aan de lysosomale afbraak Signup and view all the answers

Welk type weefselschade is typisch gevolg van directe immuunschade?

Auto-immuunziekten Signup and view all the answers

Welke bacteriën worden gekenmerkt door de productie van toxische eiwitten die fagocyten kunnen doden?

Staphylococcus aureus Signup and view all the answers

Welke moleculen zijn verantwoordelijk voor de hechting van bacteriën aan cellen?

Pili Signup and view all the answers

Wat is een voorbeeld van een endotooxine?

Lipopolysacharide Signup and view all the answers

Study Notes

Prions

Prion proteins (PrP sc) cause pathogenesis through accumulation in the brain.
Associated clinical diseases include Bovine Spongiform Encephalitis (BSE) in cows, Creutzfeldt-Jakob Disease (CJD), and Kuru in humans.

Viruses

Viral particles are typically less than ½ micron.
Composed of a DNA/RNA core (genome) and a protein coat called capsid; some have a lipid envelope.
Viruses often require a host for replication and transmission.

Bacteria

Identified using Gram staining with crystal violet:
- Gram-positive: Thick wall, single phospholipid layer.
- Gram-negative: Thin wall, double phospholipid layers.
Shapes include cocci (spherical) and bacilli (rod-shaped).
Oxygen requirements:
- Aerobic: Require oxygen.
- Anaerobic: Do not require oxygen.

Fungi

Grows in forms such as yeasts and hyphae (can be septate or aseptate).
Candida is the most prevalent fungal pathogen.
Infections can be superficial (e.g., dermatophytes) or deep (e.g., histoplasmosis, blastomycosis, coccidioidomycosis).
Opportunistic fungi include Candida, Aspergillus, Mucor, and Cryptococcus.

Protozoa

Can reside in intestines or blood.
Notable examples include Plasmodium (malaria), Leishmania, Trypanosoma, Toxoplasma, and Giardia.

Helminths

Include roundworms (nematodes) and tapeworms (cestodes).
Complex life cycles involve sexual and asexual reproduction.
Key species include Ascaris and Taenia (types: solium vs. saginata).

Diagnostic Techniques

Utilizes Hematoxylin and Eosin stains for histology.
Employs special stains like Gram-positive/negative, acid-fast, silver, and Giemsa stains.
Detection includes serum tests for pathogen-specific antibodies and molecular diagnostics like Polymerase Chain Reaction (PCR).

Agents of Bioterrorism

Classified into three categories:
- Category A: Highest risk.
- Category B: Moderate risk.
- Category C: Emerging threats.

Emerging Infectious Diseases

Recent examples include:
- SARS (2003)
- Swine Flu (2009)
- Ebola (2014)
- Chikungunya (2014)
- Zika (2015)
- COVID-19 (SARS-CoV-2, from December 2019).

Microbial Entry Routes

Common entry methods for microbes include:
- Skin, gastrointestinal tract, respiratory tract, and urogenital tract.
- Methods of entry: inhalation, ingestion, sexual transmission, insect/animal bites, and injection.

Infection Mechanisms

Various pathogens exert damage through:
- Cell contact/entry.
- Toxin release leading to necrosis.
- Activation of the immune response resulting in tissue damage.

Viral Hemorrhagic Fevers

Caused by enveloped RNA viruses like Arenaviruses, Filoviruses, Bunyaviruses, and Flaviviruses.
Present clinical spectrum includes mild fevers to life-threatening conditions with sudden hemodynamic deterioration.

Herpes Simplex Virus (HSV)

Causes conditions like gingivostomatitis (HSV1) and genital herpes (HSV2).
Clinically presents with self-limiting cold sores and can lead to severe neurological complications.

Cytomegalovirus (CMV)

Infects monocytes and bone marrow progenitors; transmission occurs via various routes including saliva and organ transplants.
Reactivation can occur in immunocompromised individuals.

Hepatitis B Virus

Causes acute and chronic infections; transmission can occur percutaneously, perinatally, or sexually.
Primary target is hepatocytes, and immune response contributes to liver injury.

Epstein-Barr Virus (EBV)

Causes infectious mononucleosis and is associated with conditions like lymphomas and nasopharyngeal carcinoma.
Transmitted primarily through saliva.

Immunity

Two types exist:
- Innate immunity: Physical barriers and immune cell responses.
- Adaptive immunity: Develops after exposure, involving T and B cells.
Pathogens may employ immune evasion strategies including antigenic variation and suppression of immune responses.

Categories of Infectious Agents

Prions: Misfolded proteins causing diseases like Creutzfeldt-Jakob Disease.
Viruses: Obligate intracellular pathogens with a protein coat; examples include poliovirus (causes poliomyelitis).
Bacteria: Varied size and reproduction methods; can be gram-positive or gram-negative; examples include Streptococcus pneumoniae (pneumonia).
Fungi: Includes yeasts and hyphae; Candida albicans is the most prevalent fungus; infections include thrush and histoplasmosis.
Protozoa: Diverse group causing diseases like malaria (Plasmodium) and Chagas disease (Trypanosoma cruzi).
Helminths: Parasites such as roundworms and tapeworms, with complex life cycles; examples include Ascaris and Taenia.

Viruses Overview

Generally smaller than half a micron; consist of DNA/RNA core and protein capsid.
May have a lipid envelope for protection.

Bacterial Classification

Gram staining distinguishes between gram-positive (thicker wall) and gram-negative (thinner wall) bacteria.
Shapes include cocci (spherical) and bacilli (rod-shaped).
Can be aerobic (require oxygen) or anaerobic (do not require oxygen).

Fungal Infections

Superficial infections caused by dermatophytes affecting skin (e.g., tinea).
Deep infections can form granulomas; opportunistic fungi include Candida and Aspergillus.

Methods of Entry for Microbes

Common entry routes: skin, gastrointestinal tract, respiratory tract, urogenital tract.
Ingress methods: inhalation, ingestion, adherence through adhesins and pili.

Bacteriological Toxins

Types include endotoxins (part of bacterial cell walls) and exotoxins (secreted proteins affecting host cells).
Neurotoxins (e.g., botulinum toxin) disrupt normal cell functions.

Immune Evasion Mechanisms

Microbes can evade immune responses by being inaccessible, undergoing antigenic variation, resisting innate immunity, or inhibiting T-cell responses.
Specific strategies include fast cell invasion, dense capsule formation, and modifying lipopolysaccharide structures.

Tuberculosis Overview

Approximately 1.7 billion individuals globally infected; 8.7 million new cases annually.
Major risk factors: AIDS, diabetes, chronic diseases, immunosuppression.
Primary tuberculosis affects previously unexposed individuals; symptoms resemble acute bacterial infections.

Diagnosis of Tuberculosis

Diagnosis includes physical examination, chest X-rays, acid-fast smears, and sputum cultures, with culture being the gold standard for drug susceptibility testing.

Epstein-Barr Virus (EBV)

Causes infectious mononucleosis and is associated with lymphomas and nasopharyngeal carcinoma.
Primarily transmitted via saliva; known as kissing disease.

Emerging Infectious Diseases

Notable recent outbreaks include SARS (2003), swine flu (2009), Ebola (2014), Chikungunya (2014), Zika (2015), and COVID-19 (SARS-CoV-2).

Immunological Response to Infections

Direct tissue damage can occur through immune responses, leading to chronic conditions like cirrhosis in the case of viral hepatitis.
Post-infectious syndromes like rheumatic fever can arise from immune responses to infections, particularly streptococcal infections.

Mycobacterium Overview

Includes pathogenic species like Mycobacterium tuberculosis and Mycobacterium leprae, which affect both lungs and skin/nerves respectively.
Characterized by acid-fast staining properties.

General Pathogen Characteristics

Bacteria can be gram-positive or gram-negative with specific virulence factors.
Viral infections can lead to serious diseases like hepatitis and various cancers, highlighting the need for effective diagnostics and treatments.

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Description

Explore the fascinating world of pathogens in this quiz, covering prion proteins, viruses, and bacteria. Learn about the characteristics, pathogenesis, and clinical implications of prion diseases such as BSE and CJD, alongside the structure of viruses and bacteria. Test your knowledge on these critical biological concepts.