Chapter 14

Question 1

_____ and ____ membranes are physical barriers to infection

Answer 1

Skin and Mucous

-May supply foundation for microbial ecosystem

Question 2

Humans are usually _____ in utero

Answer 2

Sterile

-soon after birth microbial populations begin to establish

Question 3

Normal microbiota

Answer 3

• Resident flora

- transient flora

Question 4

Isolated colonies in specific body regions. List regions

Answer 4

Nose,Throat, Large intestine, Mouth, Skin, Vagina, Urethra

Question 5

Factors that influence distribution

Answer 5

• nutrient availability
• salinity
• oxygen availability
• host defenses
• mechanical factors

Question 6

The dominant type of organism my change with _____ and ______

Answer 6

age and situation

Question 7

Normal flora play a role in defenses

Answer 7

• Protection from colonization by pathogens

- microbial antagonism

Question 8

Microbial antagonism

Answer 8

• competitive exclusion

- bacteriocins

Question 9

Symbiotic relationships form between microbes and host

Answer 9

• Relationships may change depending on state of hose and attributes of microbes
• Mutualism
• Commonsalism
• Parasitism

Question 10

Mutualism

Answer 10

++
Intestinal bacteria
Probiotics

Question 11

Commonsalism

Answer 11

+ neutral

Flora on skin and conjunctiva

Question 12

Parasitism

Answer 12

+-

Pathogens

Question 13

Pathogenicity

Answer 13

State of host resistance usually determines extent of infection

• primary infection
• secondary infection (typically opportunistic)
• Sub-clinical (inapparent) infection

Question 14

Distribution of Pathogens

Answer 14

Local infection

Systemic (generalized) infection

Question 15

Systemic infection

Answer 15

Septicemia can result from

• Bacteremia
• Toxemia
• Viremia

Question 16

Many people are carriers of pathogens. Why are they less affected or not at all?

Answer 16

.

Question 17

Predisposing factors

Answer 17

gender
genetic background
climate and weather
inadequate nutrition
age
habits and lifestyle
chemotherapy
emotional disturbances

Question 18

Characteristics of infectious disease

Answer 18

communicable
-contagious
-often reflects ID50
non-communicable disease

Question 19

Robert Koch demonstrated that specific microbes caused specific diseases

Answer 19

Experimented with grazing animals infected with anthrax

Question 20

Koch’s postulates

Answer 20

• Same pathogen must be present in each case of disease
• Pathogen is isolated from diseased hose and grown in pure culture
• Pure culture must cause disease when inoculated into healthy animal
• Pathogen must be re-isolated from inoculated animal

Question 21

Exceptions to Koch’s postulates

Answer 21

• Some bacteria have unique culture requirements
• some diseases are caused by multiple pathogens (polymicrobial diseases [Mixed infections])
• Ethical considerations

Question 22

States of an Infectious disease

Answer 22

Incubation
Prodromal period
Illness
Decline
Convalescance

Question 23

In order to cause disease pathogen must follow a series of steps

Answer 23

Gain entrance to host
Adherence
Colonization
Avoid hose defenses
Cause host damage

Question 24

Adherence

Answer 24

critical step

binding of adhesins to host receptors is highly specific

Question 25

Virulence factors

Answer 25

capsules
incomplete phagocytosis
fimbrae
components of cell wall