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Questions and Answers
Which mechanism is primarily responsible for the adherence of Gram-positive bacteria to host cells?
Which mechanism is primarily responsible for the adherence of Gram-positive bacteria to host cells?
What is a common feature of toxins produced by Gram-negative bacteria?
What is a common feature of toxins produced by Gram-negative bacteria?
Which characteristic is used by HIV to specifically adhere to host cells?
Which characteristic is used by HIV to specifically adhere to host cells?
Which method do bacteria commonly use to survive within a host's phagocyte?
Which method do bacteria commonly use to survive within a host's phagocyte?
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Which of the following is a mechanism of antibiotic resistance?
Which of the following is a mechanism of antibiotic resistance?
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What role do exogenous sources have in infectious disease transmission?
What role do exogenous sources have in infectious disease transmission?
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Which bacterial species is known for producing an A-B toxin that disrupts synaptic transmission?
Which bacterial species is known for producing an A-B toxin that disrupts synaptic transmission?
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What is the key feature of multidrug-resistant transporters in bacteria?
What is the key feature of multidrug-resistant transporters in bacteria?
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Which process can bacteria employ to avoid phagocytosis?
Which process can bacteria employ to avoid phagocytosis?
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What type of sources can be classified as endogenous in relation to infectious diseases?
What type of sources can be classified as endogenous in relation to infectious diseases?
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What factor has been suggested to help differentiate between pre- and post-capillary causes of exercise pulmonary hypertension (PH)?
What factor has been suggested to help differentiate between pre- and post-capillary causes of exercise pulmonary hypertension (PH)?
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Which statement best describes the classification of pulmonary hypertension (PH)?
Which statement best describes the classification of pulmonary hypertension (PH)?
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What is the global prevalence of pulmonary hypertension (PH), as stated in the content?
What is the global prevalence of pulmonary hypertension (PH), as stated in the content?
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What recommendation was made regarding the clinical classification of PH after the 6th World Symposium on Pulmonary Hypertension?
What recommendation was made regarding the clinical classification of PH after the 6th World Symposium on Pulmonary Hypertension?
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In the context of pulmonary hypertension, what does the term 'common condition' refer to?
In the context of pulmonary hypertension, what does the term 'common condition' refer to?
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What percentage of PH cases worldwide are accounted for by groups 2 and 3 PH?
What percentage of PH cases worldwide are accounted for by groups 2 and 3 PH?
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Which phrase indicates the change made in the 2022 ESC/ERS guidelines regarding PH groups 2, 3, and 4?
Which phrase indicates the change made in the 2022 ESC/ERS guidelines regarding PH groups 2, 3, and 4?
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What is a characteristic of patients with severe PH in the context of underlying conditions?
What is a characteristic of patients with severe PH in the context of underlying conditions?
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What proportion of PAH patients might have cardiopulmonary comorbidities in current clinical registries?
What proportion of PAH patients might have cardiopulmonary comorbidities in current clinical registries?
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What is a significant reason for maintaining the current clinical classification of PH as proposed in the content?
What is a significant reason for maintaining the current clinical classification of PH as proposed in the content?
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Study Notes
Infectious Diseases - Transmission and Virulence
- Mechanisms of infection: Encounter, Adherence, Evasion of Immune System, Multiplication and Spread, Cell/Tissue Damage, and Shedding.
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Sources of infection:
- Exogenous: Fomites (Listeria, E. coli, Salmonella), Animal and insect vectors (viruses, malaria, encephalitis, typhus, leptospirosis, tularemia, parasites), Other humans (Strepto pneumoniae, viruses, STDs, tuberculosis). Airborne and bodily fluids are also transmission vectors.
- Endogenous: Commensalism or mutualism, Skin-Staph, Intestines-gram negatives, anaerobes, fungi, Nasal/Oropharynx-Staph, Strep, anaerobes.
- Transmission: Most organisms have a defined survival outside of hosts, except some fungi and bacteria (like anthrax) which can form spores.
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Adherence:
- Viruses adhere and enter cells by specific receptors or proteins. Examples include Covid-19 (angiotensin II converting enzyme receptor), HIV (CD4 cell antigen).
- Gram-positive bacteria adhere through peptidoglycans in their cell walls.
- Gram-negative bacteria adhere through antigens on flagella, pili, or fimbriae.
Bacterial Characteristics and Biological Relevance (E. coli)
- Bacterial Characteristics: H (flagella) antigen, K (cell wall) antigen, glycocalyx, lipid A, lipopolysaccharide/endotoxin, haemagglutination, haemolysis, enterochelin, aerobactin, fimbriae, hydrophobicity, urease production, resistance to cidal effect of serum, biotin production, phase variation.
- Biological Relevance: Motility, inhibition of phagocytosis by polymorphs, ureteric paralysis, impairment of kidney growth, renal scar formation, access to iron source, adhesion to urothelium, mediators of inflammation, scar formation, stone formation, impairment of polymorph function and complement-mediated lysis, hematogenous spread, protection against high urine osmolality, continued survival of bacteria in changing conditions.
Virus Replication (HIV)
- Virus Entry: gp120 binds CD4, conformational change, gp41 membrane penetration, fusion of HIV membrane with host cell membrane.
- Replication: Reverse transcriptase-mediated synthesis of proviral DNA, integration of provirus into host cell genome, cytokine activation, transcription of HIV genome, transport of viral RNAs to cytoplasm, synthesis of HIV proteins, assembly of virion core structure.
- Virus Release: Budding and release of mature virion, new HIV virion.
Spread/Multiplication
- Production of toxins: E. coli, Clostridium difficile, Super antigens-Staph.
- Secretion of enzymes: Streptolysin, proteases, Lipoprotein saccharide.
Toxin Production
- Gram-negative organisms: Endotoxin, LPS of cell wall, fever, permeability changes, vasodilation-septic shock.
- A-B toxins: Clostridium tetani, synaptic transmission, Vibrio cholera, ADP ribosylation.
Evading Host Immune Response
- Inhibition of chemotaxis: C5a-Strep, killing of phagocyte, A-toxin-Staph.
- Avoiding ingestion: LPS, k-capsule of Strep.
- Avoiding complement lysis: Coating with IgA antibodies-Nisseria.
- Surviving within phagocyte: Inhibition of endosome-lysosome fusion—Chlamydia, inhibition of NADPH oxidase—Salmonella, inhibition of H+-ATPase—tuberculosis.
Survival within Host Phagocyte
- Inhibition of Endosome—lysosome fusion—Chlamydia
- Inhibition of NADPH Oxidase—Salmonella
- Inhibition of endosomal H+-ATPase—tuberculosis
Phagocytosis
- Recognition and Attachment: Microbes bind to phagocyte receptors.
- Engulfment: Phagocyte membrane surrounds the microbe.
- Killing and Degradation: Phagosome fuses with lysosome, degradation by lysosomal enzymes.
Antibiotic Resistance
- Induction or Modification of Enzymes: Inactivating drugs, such as penicillinase cleaving β-lactam ring structure.
- Multidrug Resistant Transporter.
- Alteration of Metabolic Function.
- Phage Transfer.
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Description
Explore the mechanisms of infection, sources, and transmission of various pathogens. Understand how viruses and bacteria adhere to host cells and the role of different vectors in spreading diseases. This quiz covers essential concepts in infectious disease dynamics.
