PATHOLOGY, INFECTION, AND DISEASE

Pathology

The study of disease.

PATHOLOGY, INFECTION, AND DISEASE

Etiology

The study of the cause of a disease.

PATHOLOGY, INFECTION, AND DISEASE

Pathogenesis

The development of disease.

PATHOLOGY, INFECTION, AND DISEASE

Infection

Colonization of the body by pathogens.

PATHOLOGY, INFECTION, AND DISEASE

Disease

An abnormal state in which the body is not functioning normally.

NORMAL MICROBIOTA AND THE HOST

Transient microbiota

May be present for days, weeks, or months.

NORMAL MICROBIOTA AND THE HOST

Normal microbiota

Permanently colonize the host

NORMAL MICROBIOTA AND THE HOST

Symbiosis

Is the relationship between normal microbiota and the host.

SYMBIOSIS

Commensalim

One organism benefits, and the other is unaffected.

SYMBIOSIS

Mutualism

Both organisms benefit.

SYMBIOSIS

Parasitism

One organism benefits at the expense of the other.

SYMBIOSIS

Opportunistic pathogens

Some normal microbiota ordinarily do not cause disease in their normal habitat in a healthy person but may do so in a different environment.

NORMAL MICROBIOTA AND THE HOST

Microbial antagonism

Is a competition between microbes.

NORMAL MICROBIOTA AND THE HOST

Normal microbiota

PROTECT THE HOST BY:

1. Occupying niches that pathogens might occupy

2. Producing acids

3. Producing bacteriocins

NORMAL MICROBIOTA AND THE HOST

Probiotics

Live microbes applied to or ingested in the body, intended to exert a beneficial effect.

KOCH'S POSTULATES

1. The same pathogen must be present in every case
of the disease.

2. The pathogen must be isolated from the diseased
host and grown in pure culture.

3. The pathogen from the pure culture must cause
the disease when it is inoculated into a
healthy, susceptible laboratory animal.

4. The pathogen must be isolated from the
inoculated animal and must be shown to be the
original organism.

KOCH'S POSTULATES: UNDERSTANDING DISEASE

Figure 14.3

1. Microorganisms are isolated from a diseased or
dead animal.

2a. The microorganism are grown in pure culture.

2b. The microorganisms are identified.

3. The microorganisms are injected into a healthy
laboratory animal.

4. Disease is reproduced in a laboratory animal.

5a. The microorganisms are isolated from this
animal and grown in a pure culture.

5b. Microorganisms are identified.

**Microorganisms in the diseased host caused the same disease in a laboratory host**

KOCH'S POSTULATES

Koch's postulates are used to prove the cause
of infectious disease:

a. Some pathogens can cause several disease
conditions.

b. Some pathogens cause disease only in humans.

CLASSIFYING INFECTIOUS DISEASES

Symptom

A change in body function that is felt by a patient as a result of disease.

CLASSIFYING INFECTIOUS DISEASES

Sign

A change in body that can be measured or observed as a result of disease.

CLASSIFYING INFECTIOUS DISEASES

Syndrome

A specific group of signs and symptoms that accompany a disease.

CLASSIFYING INFECTIOUS DISEASES

Communicable disease

A disease that is spread from one host to another.

CLASSIFYING INFECTIOUS DISEASES

Contagious disease

A disease that is EASILY spread from one host to another.

CLASSIFYING INFECTIOUS DISEASES

Non-communicable disease

A disease that is not transmitted from one host to another.

OCCURENCE OF A DISEASE

Incidence

Fraction of a population that CONTRACTS A DISEASE during a specific time.

OCCURENCE OF A DISEASE

Prevalence

Fraction of a population HAVING A SPECIFIC DISEASE at a given time.

OCCURENCE OF A DISEASE

Sporadic disease

Disease that occurs occasionally in a population.

OCCURENCE OF A DISEASE

Endemic disease

Disease constantly present in a population.

OCCURENCE OF A DISEASE

Epidemic disease

Disease acquired by many hosts in a given area in a short time.

OCCURENCE OF A DISEASE

Pandemic disease

Worldwide epidemic.

OCCURENCE OF A DISEASE

Herd immunity

Immunity in most of a population.

SEVERITY or DURATION OF A DISEASE

Acute disease

Symptoms develop rapidly.

SEVERITY or DURATION OF A DISEASE

Chronic disease

Disease develops slowly.

SEVERITY or DURATION OF A DISEASE

Subacute disease

Symptoms are between acute and chronic.

SEVERITY or DURATION OF A DISEASE

Latent disease

Disease with a period of no symptoms when the causative agent is inactive.

EXTENT OF HOST INVOLVEMENT

Local infection

Pathogens are limited to a small area of the body.

EXTENT OF HOST INVOLVEMENT

Systemic infection

An infection throughout the body.

EXTENT OF HOST INVOLVEMENT

Focal infection

Systemic infection that began as a local infection.

EXTENT OF HOST INVOLVEMENT

Sepsis

Toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection.

EXTENT OF HOST INVOLVEMENT

Bacteremia

Bacteria in the blood.

EXTENT OF HOST INVOLVEMENT

Septicemia

Growth of bacteria in the blood.

EXTENT OF HOST INVOLVEMENT

Toxemia

Toxins in the blood.

EXTENT OF HOST INVOLVEMENT

Viremia

Viruses in the blood.

EXTENT OF HOST INVOLVEMENT

Primary infection

Acute infection that causes the initial illness.

EXTENT OF HOST INVOLVEMENT

Secondary infection

Opportunistic infection after a primary (predisposing) infection.

EXTENT OF HOST INVOLVEMENT

Subclinical disease

No noticeable signs or symptoms (inapparent infection).

PREDISPOSING FACTORS

MAKE THE BODY MORE SUSCEPTIBLE TO DISEASE:

a. Short urethra in females

b. Inherited traits, such as the sickle cell gene

c. Climate and weather

d. Fatigue

e. Age

f. Lifestyle

g. Chemotherapy

RESERVOIRS OF INFECTION

CONTINUAL SOURCES OF INFECTION:

a. HUMAN: AIDS, GONORRHEA
- CARRIERS may have inapparent infections or
latent diseases.

b. ANIMAL: RABIES, LYME DISEASE
- Some ZOONOSES may be transmitted to humans.

c. NONLIVING: BOTULISM, TETANUS
- Soil.

TRANSMISSION OF DISEASES

CONTACT:

a. DIRECT: requires close association between
infected and susceptible host.

b. INDIRECT: spread by FOMITES-a nonliving object
that can spread infection.

c. DROPLET: transmission via airborne droplets.

VEHICLE TRANSMISSION

Transmission by an inanimate reservoir (food, water, air).

VECTORS

1. Arthropods, especially fleas, ticks, and
mosquitoes.

2. TRANSMIT DISEASE BY TWO GENERAL METHODS:

a. MECHANICAL TRANSMISSION: arthropod carries
pathogen on feet.

b. BIOLOGICAL TRANSMISSION: pathogen reproduces
in vector.

NOSOCOMIAL INFECTIONS

1. Are acquired as a result of a hospital stay.

2. Affect 5-15% of all hospital patients.

**Prevent direct contact transmission through the use of gloves, masks, and face shields.

NOSOCOMIAL INFECTIONS

Figure 14.9

1. Microorganisms in hospital environments.

2. Compromised host (or weakened) status of the
host.

3. Chain of transmission in the hospital.

***THE PRESENCE OF ANY ONE OF THESE FACTORS ALONE IS GENERALLY NOT ENOUGH TO CAUSE INFECTION; IT IS THE INFRACTION OF ALL THREE FACTORS THAT POSES A SIGNIFICANT RISK OF NOSOCOMIAL INFECTION.

PRINCIPLE SITES OF NOSOCOMIAL INFECTIONS

Table 14.5

1. URINARY TRACT INFECTIONS:
32% most common of nosocomial infections.

2. SURGICAL SITE INFECTIONS:
22% ranked second of nosocomial infections.

3. LOWER RESPIRATORY INFECTIONS:
15% pneumonias of nosocomial infections.

4. BLOODSTREAM INFECTIONS:
14% bacteremias of nosocomial infections.

5. OTHER:
17% all others sites of nosocomial infection.

COMMON CAUSES OF NOSOCOMIAL INFECTIONS

1. Coagulase-negative staphylococci: 15% of total
infections; 89% resistant to antibiotics.

2. S. aureus: 15% of total infections; 80%
resistant to antibiotics.

3. Enterococcus: 10% of total infections; 4-71%
resistant to antibiotics.

4. Gram-negative rods: 15-25% of total infections;
3-32% resistant to antibiotics.

5. C. difficile: 13% of total infections;
not reported resistant to antibiotics.

EMERGING INFECTIOUS DISEASES

Diseases that are new, increasing in incidence, or showing a potential to increase in the near future.

EMERGING INFECTIOUS DISEASES

CONTRIBUTING FACTORS:

a. Genetic recombination:
- E.coli O157, avian influenza (H5N1)

b. Evolution of new strains:
- V. cholera O139

c. Inappropriate use of antibiotics and pesticides:
- Antibiotic-resistant strains

d. Changes in weather patterns:
- Hantavirus

e. Modern transportation:
- West Nile virus

f. Ecological disaster, war, and expanding human
settlement:
- Coccidioidomycosis

g. Animal control measures
- Lyme disease

h. Public health failure:
- Diphtheria

EPIDEMIOLOGY

1. The study of where and when diseases occur.

2. CENTERS FOR DISEASE CONTROL AND PREVENTION
(CDC):
a. Collects and analyzes epidemiological
information in the United States.

b. Publishes MORBIDITY AND MORTALITY WEEKLY
REPORT (MMWR).

c. www.cdc.gov

EPIDEMIOLOGY

1. John Snow (1848-1849)- mapped the occurrence of
cholera in London.

2. Ignaz Semmelweis (1846-1848)- showed that hand
washing decreased the incidence of puerperal
fever.

3. Florence Nightingale (1858)- showed that
improved sanitation decreased the incidence
of epidemic typhus.

EPIDEMIOLOGY

Case reporting

Healthcare workers report specified disease to local, state, and national offices.

EPIDEMIOLOGY

Nationally notifiable diseases

Physicians are required to report occurrence.

THE CDC

Morbidity

Incidence of a specific notifiable disease.

THE CDC

Mortality

Deaths from notifiable diseases.

THE CDC

Morbidity rate

Number of people affected in relation to the total population in a given time period.

THE CDC

Mortality rate

Number of deaths from a disease in relation to the population at a given time.

The term best associated with the cause of disease is:

A) infection.
B) etiology.
C) pathogen.
D) pathogenesis.
E) parasitism.

Etiology

In a healthy human, resident microorganisms would be found in all of the following areas except:

A) bloodstream.
B) tooth and gum surfaces.
C) lower urethra.
D) nasal passages.
E) conjunctiva.

Bloodstream

Healthcare professionals who fail to use aseptic techniques can cause:

A) Predisposing factors.
B) Zoonoses.
C) Nosocomial infections.
D) Herd immunity.
E) Pathogens.

Nosocomial infections

In the human intestinal tract, E. coli produces vitamins beneficial to the host and can inhibit pathogen growth. In turn, the bacterium is supplied with nutrients and an environment for growth. This symbiotic relationship between E. coli and its host is an example of:

A) opportunism.
B) mutualism.
C) antagonism.
D) parasitism.
E) commensalism.

Mutualism

Which of the following is not an example of microbial antagonism?

A) Microbes competing with other microbes for
nutrients.
B) Microbes utilizing oxygen necessary for the
growth of other microbes.
C) Microbes producing acidic compounds that limit
the growth of many bacteria.
D) Microbes producing vitamins and growth factors
that can be utilized by the host.
E) Microbes producing compounds inhibitory to
other microbes.

Microbes producing vitamins and growth factors that can be utilized by the host.

An infection transmitted by a hypodermic needle is transmitted by:

A) Indirect contact.
B) Droplet transmission.
C) Common vehicle transmission.
D) Direct contact.
E) A vector.

Indirect contact

Which of the following is not necessary to satisfy Koch's postulates?

A) The organism must cause disease through toxin
production.
B) The organism must cause the disease when
introduced from pure culture into a healthy
host.
C) The organism must be re-isolated from the
experimentally infected diseased animal and
shown to be identical to the original isolate.
D) The organism must be grown in pure culture
outside the diseased host.
E) The organism must be present in every case of
the disease.

The organism must cause disease through toxin production.

Infectious diseases which are easily passed from host to host within a population are best described as:

A) acute.
B) noncommunicable.
C) chronic.
D) communicable.
E) contagious.

Contagious

An epidemic disease of worldwide proportions would best be described as:

A) chronic.
B) sporadic.
C) pandemic.
D) acute.
E) endemic.

Pandemic

The occurrence of streptococcal bronchopneumonia in an individual recovering from influenza is an example of a/an:

A) subacute infection.
B) secondary infection.
C) latent infection.
D) sporadic infection.
E) chronic infection.

Secondary infection

Infections in which the pathogen is distributed throughout the body are referred to as "generalized infections" or:

A) emerging infections.
B) local infections.
C) focal infections.
D) systemic infections.
E) zoonoses.

Systemic infections

In a patient with bacteremia, you would expect to find:

A) bacteria in a localized area, such as an
abscess.
B) bacteria in the blood.
C) viruses in the blood.
D) an increase in bacteria in the blood and
localized areas over time .
E) bacterial toxins in the blood.

Bacteria in the blood.

Which of the following diseases does not have a human reservoir?

A) AIDS
B) gonorrhea
C) tetanus
D) Strep infections
E) diphtheria

Tetanus

Which if the following is an example of contact transmission?

A) A person drinks from a cup used by another
individual.
B) A person develops plague from a flea bite.
C) Tuberculosis is spread from one person to
another after traveling through the air for
several meters.
D) Several people become infected with Listeria
after consuming contaminated ice cream.
E) Vacationers develop shigellosis, caused by the
intestinal pathogen Shigella sp., after
drinking contaminated water.

A person drinks from a cup used by another individual.

Vector transmission is not responsible for:

A) Lyme disease.
B) dengue.
C) influenza.
D) malaria.
E) Rocky Mountain Spotted Fever.

Influenza

Any of the following may occur in diseases transmitted by vectors except:

A) In biological transmission, vectors can
spread pathogens by vomiting.
B) In biological transmission, the vector
multiplies in the human host.
C) In biological transmission, a vector transmits
pathogens by defecating while taking a blood
meal.
D) In biological transmission, pathogens multiply
in the vector, which can transmit the pathogens
by injecting saliva directly into the host.
E) In mechanical transmission, insects contact
feces containing pathogenic bacteria and
transfer it to food.

In biological transmission, the vector multiplies in the human host.

Which of the following is the third stage of a disease?

A) period of decline
B) period of illness
C) incubation period
D) period of convalescence
E) prodromal period

Period of illness.

The morbidity rate is best defined as:

A) the percentage of infectious diseases that are
nationally notifiable.
B) the number of individuals, relative to the
population, affected by a particular disease in
a period of time.
C) the immunization rate for notifiable diseases
that can be prevented through vaccination
programs.
D) the number of individuals, relative to the
population, who have died as a result of a
particular disease in a period of time.
E) the decrease in death rate following effective
vaccination.

The number of individuals, relative to the population, affected by a particular disease in a period of time.

The ingestion of lactic acid bacteria for the purpose of preventing colonization by intestinal pathogens such as Salmonella enterica during antibiotic therapy is an example of:

A) parasitism.
B) chemotherapy.
C) probiotics.
D) vaccination.
E) opportunism.

Probiotics

An example of descriptive epidemiology is:

A) John Snow's study of the London cholera
outbreak in 1848-1849.
B) The first report of a disease occurrence.
C) Comparison of drug effectiveness in two groups
of patients.
D) Florence Nightingale's studies of disease
transmission in soldiers and civilians during
the Crimean War.
E) A study comparing disease rates in vaccinated
and non-vaccinated individuals.

John Snow's study of the London cholera outbreak in 1848-1849.

Most microorganisms are pathogenic and harmful to the human body.

A) True
B) False

False

It is possible for a host to harbor a pathogen without development of disease.

A) True
B) False

True

Disease symptoms are readily measured by health-care professionals.

A) True
B) False

False

Tetanus, which humans acquire from wounds that become infected with the soil microbe Clostridium tetani, is considered noncommunicable.

A) True
B) False

True

Transmission of Salmonella through contaminated chicken salad at a family picnic is an example of vector transmission.

A) True
B) False

False

Water can serve as a human reservoir of Vibrio cholerae.

A) True
B) False

False

In biological transmission, pathogens reproduce in the vector.

A) True
B) False

True

A nosocomial infection is one that develops as a result of a stay in a health-care facility.

A) True
B) False

True

Depending on the disease, individuals can be contagious during the incubation period, prodromal period, period of illness, period of decline, and period of convalescence.

A) True
B) False

True

For the case control method in analytical epidemiology, a group of individuals with the disease is compared to matched controls.

A) True
B) False

True

Michael woke up feeling suddenly like he was getting a sore throat and a headache. Which stage of a disease's progression is he most likely in?

A) Convalescence period
B) Prodromal period
C) Illness period
D) Incubation period
E) Decline period

Prodromal period

Tim ate raw oysters at a local restaurant and has since discovered he contracted hepatitis A. Which mode of transmission is this?

A) Vehicle transmission
B) Droplet transmission
C) Direct contact
D) Mechanical transmission
E) Airborne transmission

Vehicle transmission

Which month is the number of cases of Lyme disease the greatest?

A) July
B) December
C) August
D) January

August

Houseflies can transfer the pathogens of typhoid fever from the feces of infected people to food. This is an example of ____________ transmission.

A) Mechanical
B) Direct contact
C) Indirect contact
D) Droplet
E) Vehicle

Mechanical

The figure shows the locations of normal microbiota on and in the human body. Which of these locations has the largest numbers of resident microbiota?

A) Nose and throat
B) Reproductive systems
C) Large intestine
D) Mouth
E) Skin

Large intestine

Following coronary artery bypass surgery, seven patients develop Rhodococcus bronchialis infections. Cultures of the operating rooms, Nurse A, and Nurse B are taken. R. bronchialis grows from the hand and nasal swabs of Nurse A. The patients' infections are an example of a(n):

A) nosocomial infection.
B) emerging infectious disease.
C) communicable disease.
D) sporadic infection.

Nosocomial infection

All members of the seven families for whom Mary Mallon prepared meals developed typhoid fever. Mary did not get sick. This is an example of a(n):

A) nosocomial infection.
B) sporadic disease.
C) emerging disease.
D) carrier state.

Carrier state

The difference between normal and transient microbiota is that normal microbiota:

A) are permanently present.
B) are on the human body.
C) cause disease.
D) are opportunistic pathogens.

Are permanently present.

Robert Koch demonstrated that infectious disease:

A) all of the above.
B) is acquired by contact with an infected
person.
C) is transmitted by direct contact.
D) is caused by a microbe growing in the body.

Is caused by a microbe growing in the body.

A disease that is constantly present in a population is called a(n):

A) notifiable disease.
B) endemic disease.
C) communicable disease.
D) epidemic disease.

Endemic disease

Emergence of infectious disease can be due to all of the following reasons. Which one can be affected by changing human behavior?

A) floods
B) earthquakes
C) mutations in microbes
E) lack of vaccination

Lack of vaccination

Two patients developed endophthalmitis within 24 hours after corneal transplant surgery. The corneas have been stored in buffered media with gentamicin. Each patient had received a subconjunctival injection of gentamicin after transplantation. Streptococcus pneumoniae was isolated from conjunctival swabs of the affected eyes of both patients and from donor corneoscleral tissue. The post-transplant infections could have been prevented by:

A) the surgeon washing her hands.
B) avoiding donors who have infectious diseases.
C) aseptic techniques during surgery.
D) antimicrobial susceptibility testing of the
bacteria before surgery.

Antimicrobial susceptibility testing of the bacteria before surgery.

On October 29, Barbara participated in a study group for her Microbiology class. On November 1, Barbara had a "scratchy throat" when she swallowed. On November 2, Barbara had a headache, runny nose, and watery eyes. She was fully recovered on November 7. Identify the prodromal period for this infection.

A) Nov. 1
B) Nov. 2
C) Oct. 29-Nov. 1
D) Nov. 2-7

Nov. 1

John Snow analyzed information on cholera victims. This is an example of:

A) descriptive epidemiology.
B) case reporting.
C) controlled experimentation.
D) analytical epidemiology.

Descriptive epidemiology

Florence Nightingale compared disease statistics for soldiers before and after use of sanitation measures. This is an example of:

A) controlled experimentation.
B) descriptive epidemiology.
C) analytical epidemiology.
D) case reporting.

Analytical epidemiology

Ehrlichiosis is transmitted by Ixodes scapularis ticks. This is an example of:

A) vehicle transmission.
B) indirect contact.
C) airborne transmission.
D) arthropod vector transmission.

Arthropod vector transmission

Toxoplasmosis is transmitted to humans by cats. This is an example of:

A) direct contact.
B) vehicle transmission.
C) airborne transmission.
D) indirect contact.

Direct contact

The fungus Coccidioides immitis is found in the soil. Humans contract coccidioidomycosis by inhaling fungal spores. The reservoir for this disease is:

A) soil.
B) human.
C) animals.
D) air.

Soil

Which one of the following does not belong with the others?

A) Hantavirus
B) Brucella
C) Measles
D) Yersinia pestis

Measles

Which one of the following diseases is noncommunicable?

A) botulism
B) influenza
C) streptococcal sore throat
D) rabies

Botulism

A continual source of infection is called a:

A) carrier.
B) reservoir.
C) predisposing factor.
D) common vehicle.

Reservoir

An infection that does not cause any signs of disease is a(n):

A) secondary infection.
B) inapparent infection.
C) endemic infection.
D) sporadic infection.

Inapparent infection

Alfalfa sprouts were responsible for transmitting Salmonella to 32 people in four states. This is an example of:

A) droplet transmission.
B) indirect contact transmission.
C) vehicle transmission.
D) contact transmission.

Vehicle transmission

Two patients developed endophthalmitis within 24 hours after corneal transplant surgery. The corneas had been stored in buffered media with gentamicin. Each patient had received a subconjunctival injection of gentamicin after transplantation. Streptococcus pneumoniae was isolated from conjunctival swabs of the affected eyes of both patients and from donor corneoscleral tissue. This is an example of:

A) transmission by a fomite.
B) vehicle transmission.
C) a nosocomial infection.
D) contact transmission.

A nosocomial infection

On October 29, Barbara participated in a study group for her Microbiology class. On November 1, Barbara had a "scratchy throat" when she swallowed. On November 2, Barbara had a headache, runny nose, and watery eyes. She was fully recovered on November 7. Identify the incubation period for this infection.

A) Oct. 29-Nov. 1
B) Nov. 2-7
C) Nov. 1
D) Oct. 30

Oct. 29-Nov. 1