Chapter 10, Infection

Question 1

What are significant causes of death and morbidity related to infections?

Answer 1

Emergence of previously unknown infections, reemergence of old infections thought to be controlled, and the development of infections resistant to multiple antibiotics or vaccination.

Question 2

What constitutes the normal microbiome of the human body?

Answer 2

Microorganisms that grow and flourish in the human body.

Question 3

How is beneficial homeostasis maintained between humans and microorganisms?

Answer 3

Through the physical integrity of the gut and mechanisms that sequester microorganisms on the mucosal surface.

Question 4

What can alter the symbiotic relationship with the normal microbiome?

Answer 4

Injury that compromises protective barriers including the skin and mucous membranes.

Question 5

What are the four distinct stages of clinical infectious disease?

Answer 5

1. Incubation period 2. Prodromal state 3. Invasion period 4. Convalescence.

Question 6

What is the hallmark of most infectious diseases?

Answer 6

Fever, with body temperature regulated at a higher than normal level.

Question 7

What factors influence a pathogen’s capacity to cause disease?

Answer 7

Communicability, immunogenicity, infectivity, mechanisms of action, pathogenicity, entry portal, toxigenicity, and virulence.

Question 8

How are infectious diseases classified by prevalence and spread?

Answer 8

As endemic, epidemic, and pandemic.

Question 9

What are the steps involved in the process of infection?

Answer 9

Colonization, invasion, multiplication, and dissemination.

Question 10

What type of infections can occur when an individual’s immune system is deficient?

Answer 10

Opportunistic infections.

Question 11

What can true pathogens do in adequate numbers?

Answer 11

Circumvent an individual’s defenses and directly cause infection.

Question 12

Where do infectious microorganisms usually exist?

Answer 12

In reservoirs such as contaminated soil, contaminated water or food, breast milk, animals, or other humans.

Question 13

How can pathogens be transmitted directly?

Answer 13

Through direct physical contact, ingestion or inhalation, or placental transfer.

Question 14

What is indirect transmission of pathogens?

Answer 14

Occurs from contact with contaminated materials, ranging from towels to food or through a vector.

Question 15

How do microorganisms stabilize adherence to tissue?

Answer 15

Through surface receptors during colonization.

Question 16

Why do most microorganisms undergo rapid multiplication in tissue?

Answer 16

Because tissue is warm and nutrient-rich.

Question 17

What are some virulence factors required for successful spreading?

Answer 17

Adhesion molecules, toxins, and the ability to evade immunity.

Question 18

What can mixed species of microorganisms form?

Answer 18

Slimy biofilms that anchor themselves to surfaces and resist immune defenses.

Question 19

What is required for stable colonization of bacteria?

Answer 19

Adhesion, often through pili, surface glycoproteins, or complement-related receptors.

Question 20

What happens during invasion regarding defense mechanisms?

Answer 20

Direct confrontation with an individual’s defense mechanisms can result in bacteremia, viremia, or fungemia and sepsis.

Question 21

How can bacteria protect against phagocytosis?

Answer 21

By producing toxins that destroy phagocytic cells and extracellular enzymes that digest immune molecules.

Question 22

What classes of infectious microorganisms exist?

Answer 22

Bacterial, fungal, parasitic, protozoal, and viral.

Question 23

How are bacteria categorized?

Answer 23

Into groups such as true bacteria, filamentous, spirochetes, mycoplasma, rickettsia, and chlamydia, and as gram negative or gram positive.

Question 24

What specialized surface structures do many bacteria have?

Answer 24

Pili and flagella that promote adhesion and tissue invasion.

Question 25

What types of toxic molecules can bacteria produce?

Answer 25

Toxins that may kill cells, disrupt tissue, and protect against inflammation.

Question 26

What are exotoxins?

Answer 26

Toxins released by bacteria during growth that can damage cell membranes and inhibit protein synthesis.

Question 27

What are endotoxins?

Answer 27

Contained in the cell walls of gram-negative bacteria and released during lysis, activating inflammation and producing fever.

Question 28

What can excessive inflammatory and immune responses cause?

Answer 28

Tissue damage through excessive cytokine production and infiltration of immune cells.

Question 29

What self-protective mechanisms do bacteria have?

Answer 29

Degradation of immune molecules, neutralization of immune molecules, complement evasion, immune suppression, and escape from the phagosome.

Question 30

How can some bacteria proliferate rapidly?

Answer 30

More rapidly than the development of immune defenses, causing severe clinical disease.

Question 31

How do some bacteria evade immune defenses?

Answer 31

By surviving inside immune cells.

Question 32

What can some bacteria do to the Fc portion of antibodies?

Answer 32

Coat it, preventing complement activation or phagocytosis.

Question 33

What is antigenic variation?

Answer 33

The ability of pathogens to alter surface molecules to evade immune responses.

Question 34

How can some bacteria damage tissue?

Answer 34

By releasing molecules that bind to and neutralize antibodies or form immune complexes that deposit in tissue.

Question 35

What can some bacteria degrade?

Answer 35

Immunoglobulins or components of the complement system.

Question 36

How can some bacteria suppress immune responses?

Answer 36

By blocking T cells or impairing inflammatory signals.

Question 37

What is a major cause of hospital-acquired infections?

Answer 37

S. aureus, which has numerous virulence factors promoting invasive infection.

Question 38

What is a fungal infection called?

Answer 38

Mycosis.

Question 39

How are most pathologic fungi transmitted?

Answer 39

By human-to-human contact, inhalation, or contamination of wounds.

Question 40

What do fungi have that promotes adhesion to epithelial tissue?

Answer 40

Polysaccharide surface molecules.

Question 41

What toxins can fungi produce?

Answer 41

Toxins that promote infection, evade immune responses, or cause cancer (e.g., aflatoxins).

Question 42

What can some fungi secrete that damages tissue?

Answer 42

Enzymes that initiate pathogenic inflammatory responses, including hypersensitivity reactions.

Question 43

How do some fungi resist lysosomal destruction?

Answer 43

By surviving in phagocytes.

Question 44

What is the most common cause of fungal infections in humans?

Answer 44

C. albicans, which resides in various body sites and can remain localized in individuals with an intact immune system.

Question 45

What do parasitic organisms establish with another species?

Answer 45

A symbiosis where the parasite benefits.

Question 46

How do parasites penetrate and enter the circulatory system?

Answer 46

By adhering to and breaking down connective tissue and basement membranes.

Question 47

What are obligatory intracellular parasites?

Answer 47

Parasites that only reproduce within host cells.

Question 48

How do some parasites evade immune defenses?

Answer 48

By secreting cytotoxic molecules or through antigenic variation.

Question 49

What is malaria and how is it transmitted?

Answer 49

One of the most common infections worldwide, transmitted through the bite of an infected Anopheles mosquito.

Question 50

What is the viral life cycle?

Answer 50

Attachment, penetration, uncoating, replication, assembly, and release of new virions.

Question 51

How are viruses classified?

Answer 51

By the format of nucleic acid in the virion (RNA or DNA) and whether they use reverse transcriptase for replication.

Question 52

What mechanisms do successful viruses use to bypass immune rejection?

Answer 52

Rapid division, intracellular survival, coating with self-proteins, antigenic variation, neutralization, complement evasion, and immune suppression.

Question 53

What harmful effects can viruses have inside infected cells?

Answer 53

Inhibition of DNA, RNA, or protein synthesis; disruption of lysosomal membranes; promotion of apoptosis; and alteration of antigenic properties.

Question 54

What is an example of a viral infection?

Answer 54

Influenza, an ssRNA virus transmitted through aerosol and body fluids, with variant forms that undergo antigen shifts.

Question 55

What is AIDS?

Answer 55

AIDS is a viral disease caused by HIV.

Question 56

How does HIV affect the immune system?

Answer 56

HIV infects and depletes a portion of the immune system (Th cells), making individuals susceptible to life-threatening infections and malignancies.

Question 57

What is the global impact of HIV/AIDS?

Answer 57

HIV/AIDS remains a major cause of death worldwide.

Question 58

What has helped stabilize HIV/AIDS cases in the U.S.?

Answer 58

Aggressive antiretroviral therapy and public health campaigns have stabilized the number of new cases and deaths in the United States from HIV/AIDS.

Question 59

How is HIV transmitted?

Answer 59

HIV is a blood-borne pathogen present in body fluids with typical routes of transmission: blood or blood products, intravenous drug abuse, heterosexual and homosexual activity, and maternal-child transmission before or during birth.

Question 60

What is the primary surface receptor on HIV?

Answer 60

The primary surface receptor on HIV is the envelope glycoprotein gp120, which binds to the CD4 molecule found mostly on the surface of T-helper cells.

Question 61

What family does HIV belong to?

Answer 61

HIV is a member of the retrovirus family, which carries genetic information in the form of RNA.

Question 62

What enzymes are involved in HIV replication?

Answer 62

An enzyme, reverse transcriptase (RT), converts RNA into double-stranded DNA, and another enzyme, integrase, inserts the new DNA into the infected cell's genetic material.

Question 63

What is a major immunologic finding in AIDS?

Answer 63

The major immunologic finding in AIDS is the striking decrease in the number of CD4+ Th cells.

Question 64

What indicates infection by HIV?

Answer 64

The presence of circulating antibody against HIV indicates infection by the virus, although many individuals are asymptomatic.

Question 65

What is the current treatment for HIV infection?

Answer 65

The current treatment for HIV infection is a combination of drugs called highly active antiretroviral therapy (HAART) that attacks different portions of the viral replication pathway.

Question 66

How has mother-to-child transmission of HIV been reduced?

Answer 66

Mother-to-child transmission has been reduced to 1% with prenatal treatment of HIV infection.

Question 67

How can neonates become HIV infected?

Answer 67

Neonates become HIV infected by placental transmission or through breast-feeding.

Question 68

What increased risk do children with HIV face?

Answer 68

Children with HIV are at increased risk of coronary artery disease.

Question 69

What are effective means of countering infectious microorganisms?

Answer 69

Effective means include rigorous use of environmental infection control measures, control of insect vector populations, modern sanitation facilities, and provision of clean water and uncontaminated food supplies.

Question 70

What is passive immunotherapy?

Answer 70

Passive immunotherapy has been effective using previously formed human immunoglobulin for diseases such as hepatitides A and B, rabies, and ebola.

Question 71

What is the focus with antibiotic-resistant pathogens?

Answer 71

With antibiotic-resistant pathogens, a greater emphasis is placed on the development of new vaccines.