Microbiology Exam: Chapter 13

Front 1

normal (resident) flora

Back 1

Microbes that engage in mutual or commensual associations on you

Front 2

infection

Back 2

A condition in which pathogenic microbes penetrate host defense, enter tissues, and multiply.

Front 3

Disease

Back 3

Any deviation from health, disruption of a tissue or organ.

Front 4

Resident Flora

Back 4

-Includes bacteria, fungi, protozoa, viruses and arthropods

- Most areas of the body

- Large intestine (colon) has largest number

- Internal organs, fluids, and tissues microbe-free

Hint 4

Will be on the exam!

Front 5

microbial antagonism

Back 5

Bacterial flora benefit host by preventing overgrowth of harmful microbes.

Front 6

Portals of entry

Back 6

Characteristic route a microbe follows to enter the tissues of the body.

-skin, gastrointestinal tract, respiratory tract, urogenital tract, transplacental

Front 7

Requirements for an Infectious Dose (ID)

Back 7

• Minimum number of microbes required for infection to proceed.

• Microbes with small IDs have greater virulence.

Front 8

Adhesion

Back 8

microbes gain a stable foothold at the portal of entry; dependent on binding between specific molecules on host and pathogen

• examples: fimbrae, flagella, adhesive slimes or capsules, cilia, Suckers, hooks, barbs

Front 9

Surviving Host Defenses

Back 9

• The initial response of host defenses comes from phagocytes (WBC).

• Antiphagocytic factor: used to avoid phagocytosis

• Species of Staphylococcus and streptococcus produce leukodins, toxic to WBCs.

• Slime layer or capsule: makes phagocytosis difficult

Front 10

Virulence factors

Back 10

severity of disease

Front 11

Toxigenicity

Back 11

• Capacity to produce toxins at the site of multiplication.

• toxins = poisons

-endotoxins: lipid A of Gram- bacteria.

-exotoxins: proteins secreted by Gram + and Gram- bacteria.

Front 12

4 Different stages of clinical infections

Back 12

1. Incubation period

2. Prodromal stage

3. Period of invasion

4. Convalescent period

Front 13

Patterns of Infections

Back 13

• Primary infection

• Secondary Infection

• Acute infection

• Chronic infection

Front 14

Signs vs. symptoms

Back 14

• Sign: objective evidence of disease as noted by an observer

Examples: fever, septicemia, chest sounds, rash, leukocytosis

• Symptoms: Subjective evidence of disease as sensed by patient.

Examples: chills, pains, nausea, ache, headache, fatigue

Front 15

Signs and symptoms of inflammation

Back 15

• Earliest symptoms of disease as a result of the activation of the body defenses.

• Signs of inflammation:

- edema: accumulation of fluid

- granulomas and abscesses: walled-off collections of inflammatory cells and microbes

- lymphadenitis: swollen lymph nodes

Front 16

Signs of infection in the blood

Back 16

• Changes in the number of circulating white blood cells.

- Leukocytosis: increase in white blood cells

- leukopenia: decrease in white blood cells

- septicemia: microorganisms are multiplying in the blood and present in large numbers.

Front 17

Asymptomatic (subclinical) infections

Back 17

Although infected, host shows no signs of disease.

Front 18

Portals of Exit

Back 18

• Pathogens depart by a specific avenue; greatly influences the dissemination of infection.

- respiratory: mucus, sputum, nasal drainage, saliva

- skin scales

- fecal exit

- urogenital tract

- removal of blood

Front 19

Vector

Back 19

A live animal (other than human) that transmits an infectious agent from one host to another.

• Majority are arthropods - fleas, mosquitoes, flies, and ticks.

• Some larger animals can also spread infection - mammals, birds, lower vertebrates.

Front 20

Acquisition and transmission of infectious agents

Back 20

• Communicable disease: spreads

• Highly communicable disease: contagious, spreads very easily

• Non-Communicable: does not arise through transmission from host to host

Front 21

Nosocomial Infections

Back 21

• Any disease developed during hospital stay.

• Obtained from surgical procedures, equipment, personnel, and exposure to drug-resistant microorganisms.

Front 22

Number of Nosocomial Infections

Back 22

• 2 to 4 million cases per year with approx. 90,000 deaths.

• 1/3rd of infections can be prevented.

Front 23

Most Common Infection sites of Nosocomial Infections

Back 23

1. Urinary tract (39%)

2. Respiratory tract (18%)

3. Surgical incisions (17 %)

Front 24

Epidemiology

Back 24

The study of the frequency and distribution of disease and health-related factors in human populations.

Front 25

Endemic

Back 25

Steady frequency of disease in a particular area.

Front 26

Epidemic

Back 26

When prevalence of disease is increasing beyond what is expected.

Front 27

Pandemic

Back 27

Epidemic across the world.

Front 28

Koch's Postulates

Back 28

Determining the causative or etiologic agent of infectious disease:

- Find evidence of a particular microbe in every case of a disease.

- Isolate that microbe from an infected subject and cultivate it artificially in the lab.

- Inoculate a susceptible healthy subject with the laboratory isolate and observe the disease.

- Reisolate the agent from this subject.

Front 29

Incubation period

Back 29

time from contact to first symptoms

Front 30

Prodromal Stage

Back 30

Vague feelings of discomfort

Front 31

Period of Invasion

Back 31

High levels of microbes causing severe signs and symptoms.

Front 32

Convalescent period

Back 32

Symptoms decline, start to feel better.

Front 33

Primary Infection

Back 33

initial infection

Front 34

Secondary Infection

Back 34

Another infection by a different microbe.

Front 35

Acute Infection

Back 35

Comes on rapidly, with severe but short-lived effects.

Front 36

Chronic Infection

Back 36

Progress and persist over a long period of time.