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Microbiology > Human Microbe Interaction > Flashcards

Human Microbe Interaction Flashcards

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Biology 101 flashcards
1
Q

A condition in which pathogenic microorganisms penetrate host
defenses, enter the tissues, and multiply

A

Infection

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2
Q

A condition in which pathogenic microorganisms penetrate host
defenses, enter the tissues, and multiply

A

Infection

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3
Q

Any deviation from health

A

Disease

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4
Q

Factors that cause disease

A
  • Infections
    – Genetics
    – Aging
    – Malfunctions of systems or organs
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5
Q

Disruption of tissues or organs caused by microbes or their products

A

Infectious disease

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6
Q
  • Large and diverse collection of microbes living on and in the body
  • Also known as resident or indigenous biota or normal flora
  • Include an array of bacteria, fungi, protozoa, and viruses
A

Resident biota

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7
Q
  • Human cells contain 21,000 protein encoding genes; microbes that inhabit humans contain 8 million
  • We have a lot of microbes in places we used to think were sterile
  • All healthy people harbor potentially dangerous pathogens, but in low numbers
A

The human microbiome project

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8
Q

The makeup of your _____ can influence many facets of your overall health

A

Intestinal/gut Biota

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9
Q

Sites Definitively Known to Harbor Normal Microbiota:

A

• Skin and adjacent mucous membranes
• Upper respiratory tract
• Gastrointestinal tract, including mouth
• Outer portion of urethra
• External genitalia
• Vagina
• External ear canal
• External eye (lids, conjunctiva)

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10
Q

•Additional Sites Now Thought to Harbor At Least Some Normal Microbiota (or Their DNA)

A

• Lungs (lower respiratory tract)
• Bladder (and urine)
• Breast milk
• Amniotic fluid and fetus
• Sites in Which DNA from Microbiota Has Been Detected
• Brain
• Bloodstream

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11
Q

Factors That Weaken Host Defenses and Increase Susceptibility to Infection

A

• Age: the very young and the very old
• Genetic defects in immunity and acquired defects in immunity (AIDS)
• Pregnancy
• Surgery and organ transplants
• Underlying disease: cancer, liver malfunction, diabetes
• Chemotherapy/immunosuppressive drugs
• Physical and mental stress
• Other infections

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12
Q
  • Caused by biota already in the body
  • Can occur when normal biota is introduced to a site that was previously sterile
    – Example: Escherichia coli entering the bladder, resulting in a UTI
A

Endogenous Infections

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13
Q
  • A microbe whose relationship with its host is parasitic
  • Results in infection and disease
A

Pathogen

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14
Q

Capable of causing disease in healthy persons with normal immune systems

A

True Pathogens

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15
Q

Cause disease when:
– The host’s defenses are compromised

A

Opportunistic pathogen

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16
Q

A system of biosafety categories adopted by the Centers for Disease Control and Prevention (CDC)

Based on the general degree of pathogenicity and the relative danger in handling these pathogens

A

Biosafety levels

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17
Q

Applies to all microorganisms

A

Virulence

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18
Q

Any characteristic or structure of the microbe that contributes to toxin production or induction of an injurious host response

A

Virulence factor

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19
Q

a minimum number of microbes required for an infection to proceed

Determined experimentally for many microbes

Microbes with a smaller infectious dose have greater virulence

A

Infectious dose

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20
Q

• A characteristic route taken by a microbe to initiate infection
• Usually through skin or mucous membranes
• Source of the infectious agent:

A

Portal of entry

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21
Q

originating from outside the body – The environment,another person,or animal

A

Exogenous

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22
Q

already existing on or in the body – Normal biota or a previously silent infection

A

Endogenous

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23
Q

Sites of entry of infectious agents

A
  • Nicks
    • Abrasions
    • Punctures, some tiny and inapparent
    • Intact skin is a very tough barrier that few microbes can penetrate
    • Some infectious agents create their own passageways into the skin using digestive enzymes
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24
Q

Common infections of the fetus and neonate: TORCH

A

• Toxoplasmosis

• Other diseases: syphilis, coxsackievirus, varicella-zoster virus, AIDS, chlamydia

• Rubella

• Cytomegalovirus

• Herpes simplex virus

• The most serious complications are spontaneous abortion, congenital abnormalities, brain damage, prematurity, and stillbirths

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25
Q

• A process by which microbes gain a more stable foothold on host tissues

• Dependent on binding between specific molecules on both the host and pathogen

• A particular pathogen is limited to only those cells and organisms to which it can bind

• Once attached, a pathogen can invade body compartments

A

Adhesion

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26
Q

Chemical communication between nearby bacteria critical to establishment of infection

A

Quorum sensing

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27
Q

White blood cells that engulf and destroy pathogens by means of enzymes and antimicrobial chemicals

A

Phagocytes

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28
Q

• Virulence factor used by pathogens to avoid phagocytes
• Circumvent some part of the phagocytic process

A

Antiphagocytic factors

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29
Q

Steps Involved When a Microbe Causes Disease in a Host

A
  1. Finding a portal of entry
  2. Attaching firmly and negotiating the microbiome
  3. Surviving host defenses
  4. Causing damage
  5. Exiting host
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30
Q
  • Secreted by pathogenic bacteria, fungi, protozoa, and worms
  • Break down and inflict damage on tissues
  • Dissolve host’s defense barriers and promote the spread of microbes into deeper tissues
A

Exoenzymes

31
Q

Examples of exoenzyme

A
  • Mucinase
  • Keratinase
  • Hyaluronidase
32
Q

A specific chemical product of microbes, plants, and some animals that is poisonous to other organisms

A

Toxins

33
Q

Secreted by a living bacterial cell to the infected tissues
Many types

A

Exotoxin

34
Q

• Not actively secreted
• Shed from the outer membrane
• Only found in gram-negative bacteria

A

Endotoxin

35
Q

is a trait not solely determined by microorganisms

A

Pathogenicity

36
Q

• Microbe enters the body and remains confined to a specific tissue:
• Boils
• Fungal skin infections
• Warts

A

Localized infection

37
Q

• When an infection spreads to several sites and tissue fluids, usually in the bloodstream
• Viral: measles, rubella, chickenpox, AIDS
• Bacterial: brucellosis, anthrax, typhoid
fever, syphilis
• Fungal: histoplasmosis, cryptococcosis
• Infectious agents can also travel by means of nerves (rabies) or cerebrospinal fluid (meningitis)

A

Systemic infection

38
Q

• Exists when the infectious agent breaks loose from a local infection and is carried to other tissues
• Examples:
• Tuberculosis
• Streptococcal pharyngitis: scarlet fever
• Toxemia: infection remains localized, toxins are carried through the blood to the target tissue

A

Focal infection

39
Q
  • Several agents establish themselves simultaneously at the infection site
  • Polymicrobial diseases: gas gangrene, wound infections, dental caries, human bite infections
A

Mixed Infection

40
Q

Initial infection

A

Primary Infection

41
Q

Occurs when a primary infection is complicated by another infection caused by a different microbe

A

Secondary infection

42
Q

Come on rapidly
Have short lived effects

A

Acute infections

43
Q

Progress and persist over a long period of time

A

Chronic infections

44
Q

• Any objective evidence of disease as noted by an observer
• More precise than symptoms

A

Sign

45
Q

Subjective evidence of disease as sensed by the patient

A

Symptom

46
Q

A disease identified or defined by a certain complex of signs and symptoms

A

Syndrome

47
Q

Common signs of infectious diseases

A

• Fever
• Septicemia
• Microbes in tissue fluids
• Chest sounds
• Skin eruptions
• Leukocytosis
• Leukopenia
• Swollen lymph nodes
• Abscesses
• Tachycardia (increased heart rate)
• Antibodies in serum

48
Q

Common symptoms of infectious diseases

A

• Chills
• Pain, ache, soreness, irritation
• Malaise
• Fatigue
• Chest tightness
• Itching
• Headache
• Nausea
• Abdominal cramps
• Anorexia (lack of appetite)
• Sore throat

49
Q

Earliest symptom of disease

A

Inflammation

50
Q

Accumulation of fluid in afflicted tissue

A

Edema

51
Q

Walled-off collections of inflammatory cells and microbes in the tissues

A

Granulomas and Abscesses

52
Q

Swollen lymph nodes

A

Lymphadenitis

53
Q

Signs of infection in blood

A

Leukocytosis:
• Increase in the level of white
blood cells

Leukopenia:
• Decrease in the level of white blood cells

Septicemia:
• General state in which microbes are multiplying in the blood and are present in large numbers

Bacteremia
• Small numbers of bacteria are present in the blood but not necessarily multiplying

Viremia:
• Presence of viruses in the blood, whether or not they are actively multiplying

54
Q

• Host is infected but does not manifest the disease
• Patient experiences no symptoms or disease and does not seek medical attention
• Most infections are attended by some sort of sign

A

Asymptomatic, subclinical, or inapparent infections

55
Q

• Avenue for pathogens to exit the host
• Secretion
• Excretion
• Discharge
• Sloughed tissue

A

Portals of exit

56
Q

• The outer layer of skin and scalp is constantly being shed into the environment
• Household dust is composed of skin cells
• A single person can shed several billion skin cells a day

A

Skin Scales

57
Q

• A dormant state of an infectious agent
• During this state, a microbe can periodically become active and produce a recurrent disease
• The agents of syphilis, typhoid fever, tuberculosis, and malaria also enter into latent stages

A

Latency

58
Q

• A dormant state of an infectious agent
• During this state, a microbe can periodically become active and produce a recurrent disease
• The agents of syphilis, typhoid fever, tuberculosis, and malaria also enter into latent stages

A

Latency

59
Q

• Long-term or permanent damage to organs and tissues
• Meningitis can result in deafness, strep throat can lead to rheumatic heart disease, Lyme disease can cause arthritis, and polio can produce paralysis

A

Sequelae

60
Q

The time from initial contact with the infectious agent to the appearance of first symptoms

A

Incubation period

61
Q

When the earliest notable symptoms of infection appear

A

Prodromal period

62
Q

Infectious agent multiplies at high levels, exhibits its greatest virulence, and becomes well established in its target tissue

A

Acute phase

63
Q

Infectious agent multiplies at high levels, exhibits its greatest virulence, and becomes well established in its target tissue

A

Acute phase

64
Q

Patient responds to infection and symptoms decline

A

Convalescent stage

65
Q

Where do Pathogens Persist

A
  • Reservoir:
    • Primary habitat in the natural world from which a pathogen originates
    • Human or animal carrier; soil, water, or plants
  • Source:
    • Distinct from a reservoir
    • Individual or object from which an infection is acquired
66
Q

Where do pathogens persist

A
  • Reservoir:
    • Primary habitat in the natural world from which a pathogen originates
    • Human or animal carrier; soil, water, or plants
  • Source:
    • Distinct from a reservoir
    • Individual or object from which an infection is acquired
67
Q

2 types of vectors

A

• Biological vector:
– Actively participates in a pathogen’s life cycle, serving as a site
in which the pathogen can multiply or complete its life cycle
– Communicates the infectious agent to the human host by
biting, aerosol formation, or touch

• Mechanical vectors:
– Not necessary to the life cycle of an infectious agent
– Merely transport the pathogen without being infected

68
Q

a live animal that transmits an infectious agent from one host to another

A

Vectors

69
Q

An infection indigenous to animals but also transmissible to humans
• Human is the dead-end host and does not contribute to the natural persistence of the microbe
• Spread of disease is promoted by close associations of humans with animals
• People in animal-oriented or outdoor professions are at greatest risk
• Examples: rabies, hantavirus, West Nile virus, anthrax, plague, ringworm, toxoplasmosis, tapeworm

A

Zoonosis

70
Q

• Microbes have adapted to nearly every habitat in the biosphere
• Soil, water, air, the built environment
• Most are saprobic and cause little harm to humans
• Some are opportunists
• A few are regular pathogens
• Example: the TB bacterium, can be directly transmitted to humans when they come in contact with contaminated soil, water, or air

A

Non living reservoirs

71
Q

Acquisition and Transmission of Infectious Agents

A
  • Communicable disease:
    • Occurs when an infected host can transmit the infectious agent to another host and establish infection in that host
  • Contagious:
    • The agent is highly communicable, especially through direct contact
  • Noncommunicable:
    • Does not arise through transmission of the infectious agent from host to host
72
Q

Horizontal versus Vertical Transmission

A

Horizontal transmission:
• Disease is spread through a population from one infected individual to another
• Direct (contact) transmission: kissing and sex (Epstein-Barr virus, gonorrhea)

Indirect transmission: fomites, vehicles, parenteral (via injection into deeper tissues)
• Vector transmission
• Vertical transmission:
• Transmission from parent to offspring via ovum, sperm, placenta, or milk

73
Q

Dried microscopic residues created when microscopic pellets of mucus and saliva are ejected from the mouth and nose

A

Droplet nuclei

74
Q

Suspensions of fine dust or moisture particles in the air that contain live pathogens

A

Aerosols

Microbiology (7 decks)

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