Questions and Answers
What is the primary function of bacterial pili in the stages of infection?
Which of the following is NOT a common mode of transmission of infectious diseases?
What is the primary source of Clostridium species that are transmitted to humans?
Which stage of infection involves the growth of bacteria at the site of adherence?
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What is the term for inanimate objects that serve as a source of microorganisms that can cause infectious diseases?
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Which of the following is an example of a zoonotic disease, where bacteria that commonly cause disease in humans exist primarily in animals?
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What is the term for the exit of pathogens from the infected patient, which usually occurs via airborne respiratory droplets or fecal contamination of food and water?
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Which stage of infection involves the production of toxins and inflammation?
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What is the primary factor that determines the infectious dose of a bacterium?
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Which of the following bacteria is an example of a pathogen that requires a higher infectious dose?
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What is the term used to describe a disease that is highly communicable?
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What is the term used to describe a person who is infected with a pathogen but shows no symptoms of disease?
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Which of the following is an example of a non-communicable infection?
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What is the term used to describe the stage of an infection where the pathogen has multiplied to sufficient numbers to cause symptoms of disease?
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Which of the following is an example of a bacterium that can cause an infection through its normal presence in the human body?
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What is the term used to describe a person who is infected with a pathogen and can transmit it to another susceptible person, even if they show no symptoms of disease?
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What is the primary mode of transmission of pathogens from mother to offspring?
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Which of the following is NOT a mode of transmission of infection?
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What is the primary defense against infection?
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What is an example of indirect contact transmission?
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What is the term for transmission of pathogens from mother to offspring?
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What is the most frequent portal of entry of pathogenic bacteria into the body?
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What is an example of inoculation transmission?
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Which of the following is an example of horizontal transmission?
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What is the primary function of adherence factors in bacterial virulence?
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What structure do Neisseria gonorrhoeae and E. coli use to attach to the urinary tract epithelium?
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What is the term for the protective matrix formed by bacteria after attachment?
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On which types of surfaces can biofilms form?
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What is a consequence of biofilm formation?
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What is the function of glycocalyx in bacteria like Staphylococcus epidermidis?
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Why are adherence mechanisms essential for certain bacteria?
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What does biofilm formation help bacteria with?
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What is the primary function of M protein in Streptococcus pyogenes?
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Which of the following mechanisms is used by intracellular bacteria to survive within host cells?
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What is the primary function of protein A in Staphylococcus aureus?
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What is the typical duration of the incubation period in acute infectious diseases?
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What is the primary characteristic of the prodrome period in acute infectious diseases?
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What is the primary difference between the diseases caused by different strains of Staphylococcus aureus?
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What is the primary function of the recovery period in acute infectious diseases?
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What is the primary mechanism used by intracellular bacteria to escape degradative enzymes within host cells?
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Study Notes
Infection and Disease
- Multiplication of normal microbiota bacteria is not considered an infection, but multiplication of pathogenic bacteria (e.g., Salmonella) is considered an infection, even if the person is asymptomatic.
- The infectious dose of bacteria varies among pathogens and depends on their virulence factors, such as pili, exotoxins, endotoxins, and capsules.
Stages of Infection
- Transmission from an external source into the portal of entry.
- Evasion of primary host defenses, such as skin or stomach acid.
- Adherence to mucous membranes, usually by bacterial pili.
- Colonization by growth of the bacteria at the site of adherence.
- Disease symptoms caused by toxin production or invasion, accompanied by inflammation.
- Host immune response to each of the mentioned stages.
Transmission of Infection
- Modes of transmission include:
- Contact (direct or indirect)
- Inhalation (droplet nuclei)
- Ingestion (food or drink contaminated by pathogens)
- Inoculation (directly into human skin or mucosa)
- Insects (vector-borne transmission)
- Congenital (vertical transmission from mother to offspring)
- Portals of entry include:
- Respiratory tract
- Gastrointestinal tract
- Genital tract
- Urinary tract
- Abnormal areas of mucous membranes and skin (e.g., cuts, burns)
Microbial Mechanisms of Pathogenicity
- Bacterial virulence factors include:
- Adherence factors (e.g., pili, capsules, glycocalyces)
- Biofilm formation
- Cell wall proteins (e.g., M protein, protein A)
- Intracellular survival mechanisms (e.g., inhibition of phagosome-lysosome fusion, escape from phagosome into cytoplasm)
Typical Stages of Infectious Disease
- Incubation period: time between acquisition of organism (or toxin) and beginning of symptoms
- Prodrome period: time during which nonspecific symptoms occur (e.g., fever, malaise, loss of appetite)
- Specific-illness period: time during which overt characteristic signs and symptoms of the disease occur
- Recovery period (convalescence): time during which the illness abates and the patient returns to a healthy state
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Description
Understanding the difference between normal microbiota and pathogenic bacteria, and the infectious dose required to cause disease. Learn about bacteria like Salmonella and Shigella that cause diarrhea.