Unit 5: Bacterial Cell Structure & Mycology & Unit 6: Parasitology & Virology Flashcards
What is the function of collagenase in pathogens?
Collagenase breaks down collagen, facilitating the spread of pathogens.
How does hyaluronidase assist in pathogen penetration?
Hyaluronidase degrades hyaluronic acid, allowing easier tissue penetration for pathogens.
What role does coagulase play in bacterial evasion of the immune system?
Coagulase causes blood to clot, helping pathogens evade the immune response.
What is mutualism in host-microbe relationships?
A relationship where both organisms benefit, like E. coli providing Vitamin K to humans.
What are the key characteristics of exotoxins?
Exotoxins are protein-based, heat labile, and released by both Gram-positive and Gram-negative bacteria.
What distinguishes commensalism from mutualism?
In commensalism, one organism benefits while the other is neither helped nor harmed.
How is parasitism defined in host-microbe interactions?
It’s a relationship where one organism benefits at the expense of another, such as disease-causing bacteria.
What is the difference between infection and infestation?
Infection involves parasitic organisms multiplying in a host, while infestation refers to larger organisms like lice.
What is an endotoxin and where is it found?
Endotoxin is lipopolysaccharide (LPS), present only in Gram-negative bacteria.
What are the key steps involved in the infectious disease process?
Entry and attachment, damage, escape, and the role of virulence factors.
What is pathogenicity?
Pathogenicity is the ability of a pathogen to cause disease, varying among different pathogens.
What role do virulence factors play in bacterial infections?
They enhance a bacterium’s ability to cause disease, including structures like fimbriae and toxins.
How do bacteria evade host defenses during infection?
By defending against immune responses, attacking host cells, hiding from detection, and using capsules.
What are inherited diseases caused by?
Inherited diseases are caused by a faulty gene.
What distinguishes congenital diseases from other disease types?
Congenital diseases result from damage during development.
What types of damage can bacteria cause during an infection?
Bacteria can cause damage through enzyme release, toxin release, and overstimulation of the immune response.
How do invasive bacteria cause disease?
Invasive bacteria spread through tissues using digestive enzymes that damage tissues.
What are adhesins and their role in bacterial attachment?
Adhesins are molecules that facilitate the attachment of bacteria to host tissues.
What are communicable diseases?
Communicable diseases can be spread from one person to another.
What is the largest organ in the body and its role in microbial colonization?
The skin is the largest organ, colonized by various microorganisms with factors that regulate their populations.
What mechanisms do viruses employ to cause disease?
Viruses multiply inside host cells, leading to cell death and altering cell cycle regulation.
Where are bacteria most densely populated in the gastrointestinal tract?
The mouth has the highest density of bacteria, while numbers increase significantly towards the end of the small intestine.
What factors influence the risk of contracting infectious diseases?
Infectious disease risk is influenced by the number of infecting organisms, virulence, and host factors like health and immune status.
What distinguishes opportunistic pathogens from regular pathogens?
Opportunistic pathogens cause disease in weakened hosts or atypical body locations, unlike primary pathogens which affect healthy individuals.
What are saprotrophs and their ecological function?
Saprotrophs decompose dead organic matter, playing a key role in nutrient cycling within ecosystems.
What are superantigens and their role in immune response?
Superantigens bind MHC class II and T-cell receptors, causing excessive cytokine release from T helper cells.
How do superantigens activate T-cells?
Superantigens activate T-cells regardless of peptide recognition, triggering proliferation and cytokine release.
What is the incubation period in infectious disease?
The incubation period is the time between infection and symptom onset.
How do pathogens breach mucosal barriers?
Pathogens exploit antigen-sampling processes, using M cells and MALT to penetrate mucous membranes.
What characterizes an acute illness?
Acute illness has a short duration where the pathogen is eliminated by host defenses.
What is the effect of Toxic Shock Syndrome Toxin (TSST)?
TSST is a superantigen that induces toxic shock via massive cytokine release.
What role do dermatophytes play in fungal pathogenesis?
Dermatophytes cause superficial infections of hair, skin, and nails by degrading keratin using keratinase enzymes.
What role do adhesins play in infection establishment?
Adhesins attach to host cell receptors, often located on pili, facilitating bacterial adherence.
How do viruses attach to host cells?
Viruses utilize specific receptors on host cells to attach and initiate infection.
Define latent illness.
Latent illness may recur if host immunity weakens, without causing symptoms.
What is Exfoliatin and its impact on the skin?
Exfoliatin destroys skin binding material, leading to scalded skin syndrome.
How can normal microbiota like Candida albicans lead to disease?
Candida albicans can cause disease in immunocompromised hosts despite being part of the normal microbiota.
What strategies does Shigella use to survive within the host?
Shigella survives phagocytosis, induces apoptosis, and utilizes actin polymerization to spread between epithelial cells.
What role do hydrolytic enzymes play in bacterial infection?
Hydrolytic enzymes break down connective tissue, aiding tissue destruction and bacterial spread.
What factors influence the incubation period?
Factors include pathogen growth rate, host condition, and infectious dose received.
What mechanisms do viruses use to evade immune responses?
Viruses block host gene expression, inhibit antiviral enzymes, and modify surface antigens.
How do bacteria evade secretory IgA during colonization?
Bacteria evade secretory IgA through rapid pili turnover, antigenic variations, and IgA protease production.
What is a characteristic feature of dimorphic fungi?
Dimorphic fungi exist as molds in the environment and develop into yeast forms in the lungs after inhalation.
How does Mycobacterium tuberculosis invade host cells?
Mycobacterium tuberculosis invades through alveolar macrophages, using surface proteins to avoid activation.
What are A-B toxins composed of?
A-B toxins consist of an A subunit, which is toxic, and a B subunit, which binds to the host cell.
How do chronic infections differ from acute infections?
Chronic infections develop slowly and last for months or years, unlike acute infections.
What strategies do pathogens use to avoid destruction by phagocytes?
Pathogens employ various means, including altering surface antigens and mimicking host molecules.
What defines a localized infection?
An infection limited to a small area, e.g., a boil from Staphylococcus aureus.
What role does normal microbiota play in protecting against pathogens?
Normal microbiota prevent pathogen attachment, compete for nutrients, and produce antimicrobial compounds.
How do some viruses evade antibody detection?
By moving cell-to-cell, inducing syncytium, and using antibodies for uptake by macrophages.
What is the function of the Type III Secretion System?
The Type III Secretion System delivers effector proteins to host cells, altering cytoskeletal structures and inducing uptake.
What strategies do protozoa and helminths use to evade the immune system?
They employ intracellular survival, antigen variation, and coating with host proteins to avoid immune detection.
What role do skin and mucous membranes play in microbial ecosystems?
They serve as barriers to pathogens and host complex ecosystems of microorganisms.
Why do some pathogens reside within host cells?
Pathogens avoid complement proteins, phagocytes, and antibodies by hiding in host cells.
What is septicemia?
An acute, life-threatening illness caused by infectious agents or their products in the bloodstream.
How do pathogens commonly breach mucous membranes?
Pathogens penetrate mucous membranes, a frequent entry point for various infections.
What types of damage do protozoan and helminth pathogens cause to the host?
Damage can result from nutrient consumption, intestinal blockage, harmful enzyme production, and immune response-induced tissue damage.
What ancient belief about diseases was common before scientific understanding?
Diseases were often viewed as divine punishment.
How do pathogens like Neisseria gonorrhoeae evade antibodies?
They produce IgA protease that cleaves IgA and use antigenic variation to change surface antigens.
What are the limitations of Koch’s postulates in establishing infectious disease causation?
Limitations include organisms that can’t be cultured, asymptomatic infections, polymicrobial diseases, and lack of suitable animal models.
What role does the protein p53 play in viral infections?
Viruses can prevent or delay apoptosis by controlling the regulatory protein p53.
What are Koch’s Postulates?
Criteria to determine the causative agent of infectious diseases, established by Robert Koch.
How do capsules help pathogens avoid phagocytosis?
Capsules interfere with opsonization and bind proteins that inactivate C3b.
How can antibiotic treatment disrupt normal microbiota?
Antibiotics can kill beneficial bacteria, allowing pathogens like Candida albicans and Clostridium difficile to overgrow.
What is an example of mutualism in the human microbiota?
Bacteria in the large intestine synthesize vitamins while receiving warmth and energy from the host.
How do A-B toxins enter host cells?
The B subunit binds to a host cell molecule, and the toxin is internalized via endocytosis.
What are Molecular Koch’s postulates related to virulence factors?
They state virulence factors should exist in pathogenic strains, disrupting them reduces virulence, and restoring them reinstates virulence.
What example illustrates how bacteria penetrate the skin?
Staphylococcus aureus enters through cuts or wounds, showcasing bacteria’s reliance on injuries for skin penetration.
Who proposed that communicable diseases were caused by living agents?
Fracastorius in 1546 suggested living agents caused communicable diseases.
What are direct effects of pathogens on hosts?
Direct effects result from toxins produced by pathogens affecting host tissue directly.
What indicates the presence of substances in the blood?
The suffix -emia, used in terms like bacteremia and viremia.
How do pathogens produce toxins in the context of infectious diseases?
Pathogens can either produce toxins that are ingested or colonize mucous membranes to produce toxins.
How do viruses manipulate MHC class I presentation?
They block MHC class I molecules or present counterfeit versions, evading T cell and NK cell detection.
How do resident and transient microbiota differ?
Resident microbiota inhabit specific sites for extended periods while transient microbiota temporarily inhabit the body.
What is the difference between colonization and infection?
Colonization is microbe establishment on surfaces, while infection involves the presence of a pathogen causing health impairment.
What important theory did Robert Koch establish in 1876?
Koch provided proof for the germ theory of disease.
What mechanisms do pathogens use to avoid phagocyte destruction?
Pathogens evade phagocyte destruction by using strategies like C5a degradation and membrane-damaging toxins.
What role does M protein play in pathogen evasion?
M protein binds regulatory proteins that inactivate C3b in Streptococcus pyogenes.
What is bacteremia?
The presence of bacteria circulating in the blood, which can be transient.
What is the significance of tissue invasion in pathogen-caused diseases?
Tissue invasion allows pathogens to evade host defenses, enhancing their ability to cause disease.
What are exotoxins and how do they work?
Exotoxins are proteins that can damage hosts, acting locally or systemically, and provoking immune responses.
What is normal microbiota and its significance?
Normal microbiota are beneficial microbes that balance human health but can cause disease opportunistically.
How do pathogens and hosts evolve together in infectious diseases?
They typically evolve towards a balanced pathogenicity, illustrated by interactions like the myxoma virus with rabbits.
How does C5a peptidase function in avoiding immune response?
C5a peptidase degrades C5a, reducing phagocyte recruitment to infection sites.
What is the significance of mucosal-associated lymphoid tissue (MALT) in immune response?
MALT development is crucial for a robust immune response, enhanced by exposure to normal microbiota.
What distinguishes primary pathogens from opportunistic pathogens?
Primary pathogens cause disease in healthy individuals, while opportunistic pathogens affect compromised hosts or unusual sites.
How do Fc receptors contribute to pathogen survival?
Fc receptors bind the Fc region of antibodies, hindering phagocyte recognition and attachment.
What is the role of hemolysins in exotoxins?
Hemolysins lyse red blood cells, causing cell lysis.
What is the role of toxoids in vaccination against toxins?
Toxoids are inactivated toxins used in vaccines to help induce immunity against harmful exotoxins.
What factors increase susceptibility to infections in immunocompromised individuals?
Factors include malnutrition, cancer, AIDS, surgery, genetic defects, and immunosuppressive therapy.
What role do capsules play in bacterial evasion of phagocytes?
Capsules inhibit phagocyte recognition and attachment, making bacteria harder to target.
What does the hygiene hypothesis suggest about microbial exposure?
Insufficient microbial exposure can increase allergy susceptibility, emphasizing the importance of normal microbiota.
Why are normal microbiota important for human health?
They are crucial for metabolic processes and immune system function.
How does Neisseria gonorrhoeae evade the complement system?
Neisseria gonorrhoeae binds complement regulatory proteins, preventing the activation of the membrane attack comple
Define virulence and its significance in infectious disease.
Virulence indicates the degree of pathogenicity of a microorganism, essential for understanding disease severity.
What mechanisms do some pathogens use to survive inside phagocytes?
Pathogens escape into the cytoplasm or prevent phagosome-lysosome fusion.
How do pathogens survive within phagocytes?
Pathogens escape phagosomes, prevent phagosome-lysosome fusion, or adapt to survive harsh environments.
What is a common example of a phospholipase toxin?
Clostridium perfringens produces a phospholipase toxin associated with gas gangrene.
How does the composition of normal microbiota change over time?
Microbiota composition is dynamic, influenced by host physiology, diet, and environmental factors.
What is an infectious dose (ID50)?
ID50 indicates the number of microbes needed to infect 50% of a population, showing pathogen survival capabilities.
Which microorganisms are commonly found in the large intestine?
Bacteroides, Escherichia, Proteus, Klebsiella, Lactobacillus, Streptococcus, Candida, Clostridium, Pseudomonas, and Enterococcus.
What are the key components involved in phagocytosis?
Key components include phagocytes, phagosomes, phagolysosomes, and digestive enzymes.
What is endotoxin composed of and what triggers an inflammatory response?
Endotoxin is composed of lipopolysaccharide (LPS); Lipid A triggers an inflammatory response.
How do symptoms differ from signs in infectious diseases?
Symptoms are subjective patient experiences, while signs are objective evidence observed by healthcare providers.
How can A-B toxins be used therapeutically?
Their structure allows for innovative vaccine development and targeted delivery of beneficial compounds.
Which pathogen is known for surviving the phagolysosome’s harsh environment?
Coxiella burnetii survives by delaying phagolysosome fusion.
How do endotoxins affect the immune system?
Endotoxins induce phagocytosis, MAC formation, and activate both innate and adaptive defenses.
What is the main difference between exotoxins and endotoxins?
Exotoxins are proteins from both Gram-positive and Gram-negative bacteria; endotoxins are only from Gram-negative bacteria and consist of Lipid A.
What damaging effects can inflammation have on host tissues?
Phagocytic cells may release enzymes and toxic products, causing tissue damage.
What consequences can arise from immune complexes formed by antigen-antibody reactions?
They can settle in kidneys and joints, activate the complement system, and lead to inflammation.
