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Questions and Answers
What is the primary mode of transmission for diseases like AIDS and Syphilis?
What is the primary mode of transmission for diseases like AIDS and Syphilis?
Which of the following diseases is transmitted via sexual intercourse?
Which of the following diseases is transmitted via sexual intercourse?
Which of the following activities is considered a form of contact transmission?
Which of the following activities is considered a form of contact transmission?
How can skin-to-skin contact lead to the transmission of certain infections?
How can skin-to-skin contact lead to the transmission of certain infections?
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What kind of transmission is primarily responsible for spreading Herpes?
What kind of transmission is primarily responsible for spreading Herpes?
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What is the characteristic range of droplet infection transmission?
What is the characteristic range of droplet infection transmission?
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Which of the following diseases can be spread through droplet infection?
Which of the following diseases can be spread through droplet infection?
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Which type of infection primarily transmits through short-distance droplets?
Which type of infection primarily transmits through short-distance droplets?
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What is NOT a typical disease associated with droplet infection?
What is NOT a typical disease associated with droplet infection?
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Which of the following conditions is least likely to be caused by droplet transmission?
Which of the following conditions is least likely to be caused by droplet transmission?
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Study Notes
Bacterial Nutrition
- Bacteria obtain nutrients through various methods
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Heterotrophic bacteria obtain food from other organisms
- Saprophytic bacteria feed on dead or decaying organic matter, like dead leaves
- Parasitic bacteria obtain food from a living host, often causing harm
- A microorganism is a pathogen if it can cause disease
- Pathogenicity is a microorganism's ability to cause disease in a specific host
Host-Parasite Relationship
- Pathogenic bacteria (parasites) multiply in host tissue, causing disease
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Non-pathogenic bacteria (commensals) live on surfaces without causing disease
- Can even benefit the host, e.g., producing vitamins
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Commensals competitively exclude pathogens
- Cover binding sites, compete for nutrients, produce toxic substances like lactic acid
- Opportunistic pathogens are normally harmless but cause disease under certain conditions
- These conditions often involve weakened host defenses
Infection and Disease
- Infection is the process where a microbe enters and multiplies in a host
- Disease is tissue damage or harm caused by the microbe
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Infectious cycle is the path a pathogen takes to cause disease
- Begins with a source of infection, often a carrier or person
- Carrier is a seemingly healthy individual carrying and spreading a pathogen
Transmission of Infections
- Contact transmission: through skin-to-skin or sexual contact
- Droplet transmission: through droplets travelling short distances
- Airborne transmission: through droplets travelling longer distances
Infection Portals of Entry
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Skin and mucous membranes: entrance sites for many infections
- Abrasions, insect bites, or injections can be entry points
- Gastrointestinal tract: pathogens enter via ingestion
- Respiratory tract: pathogens enter via inhalation
- Genitourinary tract pathogens can enter via sexual intercourse
Damage to the Host
- Pathogens cause damage
- Either at the initial infection site or by spreading throughout tissues, blood or lymphatics
- The organism must have portals of exit from the infected host
Pathogenicity
- Microbial factors are key drivers of pathogenicity
- Pathogenicity: qualitative aspect of causing disease
- Virulence: quantitative aspect of severity of disease
- Exotoxins are proteins produced by living pathogenic bacteria, and are often highly antigenic
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Endotoxins are part of the outer cell wall of Gram-negative bacteria
- Released when the cell dies and are weakly antigenic
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Toxoids are chemically deactivated toxins
- Used for vaccines to produce immunity against specific toxins
Microbial Factors
- Adherence factors: specialized structures microbes use to adhere to host cells
- Invasion factors: facilitate the entry into tissues and spread in the body
- Extracellular enzymes: help the spread of infection
Microbial Toxins
- Toxins are chemical substances damaging tissue cells
- Exotoxins: proteins secreted by living bacteria
- Endotoxins: lipopolysaccharide components of the outer membrane of Gram-negative bacteria
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Description
Explore the fascinating world of bacterial nutrition and the complex dynamics of host-parasite relationships. This quiz covers the different types of bacteria, their nutritional methods, and how they interact with their hosts. Test your understanding of pathogenic and non-pathogenic bacteria and their roles in health and disease.
