Microbiology Chapter 14

What are the types of Antiphagocytic factors?

-Bacterial capsules -Antiphagocytic chemicals

What methods do some pathogens have to avoid phagocytic destruction?

-Bacterial capsules that are composed of chemicals not recognized as foreign and are slippery -Antiphagocytic chemicals prevent fusion of lysosome and phagocytic vesicles. An example is Leukocidins that directly destroy phagocytic WBC's

What are the acquisition of normal microbiota?

-Development in womb free environment (axenic) -Microbiota begin to develop during birthing process -Much of one's resident microbiota established during first months of life -are unique to each person

How do we acquire our normal microflora?

-Development in womb free of microorganisms (axenic) -Microbiota begin to develop during birthing process -Much of one's resident microbiota established during first months of life -Are unique to each person

Difficulties in satisfying Koch's Postulates

-Diseases can be caused by more than one pathogens -Pathogens that are ignored as a potential cause of disease

What are the key ways to prevent HAIs?

-Disinfection -Surgical asepsis and sterile procedures -Isolation of contaminated objects -Establishment of nosocomial infection control committee

What conditions provide opportunities for these microbes (opportunistic infections) to cause disease?

-Introduction to normal microbiota into unusual site in body -Immune Suppression -Changes in normal microbiota

How do you control nosomial infections?

-Precautions designed to reduce factors that result in disease -Handwashing is the most effective way

Extracellular enzymes

-Secreted by the pathogen -Dissolve structural chemicals in the body -Help pathogen maintain infection, invade, and avoid body defenses

What are the potential portals of entry for pathogens?

-Skin -Placenta -Mucous membrane -Parenteral route

Exceptions of Koch's Postulates

-Some pathogens can't be cultured in the lab -Diseases caused by a combination of pathogens and other cofactors -Pathogens that require a human host

Communicable Disease

A disease that can be spread from one person or species to another.

Infection

An infection is when an organism evades a body's external defenses, multiplies, and becomes established in the body

What are the three main types of reservoirs?

Animal reservoirs Human carriers Non-living reservoirs

Antiphagocytic factors

Antiphagocytic factors prevent phagocytosis by the host's phagocytic cells

Endotoxins

Endotoxins are part of the cell wall of the pathogen -the lipid portion of the membranes lipopolysachharide -can be released when G- bacteria divide, die naturally, or are digested by phagocytic cells such as macrophages

Exotoxins

Exotoxins are secreted by the pathogen; -are central to their pathogenicity in that they destroy host cells or interfere with host metabolism

What is an HAI?

Healthcare-associated infection

Analytical Epidemiology

Investigates a disease in detail, including analysis of data acquired in descriptive epidemiology studies to determine the probable cause, mode of transmission and possible means of prevention of the disease -useful in situations when Koch's postulates cannot be applied -often retrospective, meaning they attempt to identify causation and more of transmission AFTER an outbreak has occured

Experimental Epidemiology

Involves testing a hypothesis concerning the cause of a disease -Application of Koch's Postulates is experimental epidemiology

Foodborne Transmission

Involves the contamination of food or water with an organism that can cause disease from being undercooked, or poorly refrigerated

Which of the following statements is the best definition of a pandemic disease?

It is an epidemic that occurs on more than one continent at the same time

A disease in which a pathogen remains inactive for a long period of time before becoming active is termed a(n)

Latent disease

Fill in the Blank: Endotoxin, also known as ________________________, is part of the outer membrane of G- bacteria

Lipid A

Adaptive immunity

Third line of defense responds against unique species or strains of pathogens and alters the body's defense such that they act more effectively upon subsequent infection with the specific strain

How do pathogens establish within a host?

Through adhesion or attachment using adhesion factors that include specialized structures (hooks and suckers) and attachment proteins (lipoproteins and glycoproteins)

What does it mean to be a carrier?

To be a carrier means to have the genetic code for that disease, syndrome, etc... in the makeup of a person, but to not have it yourself. You are capable of passing it onto your offspring.

Toxemia

Toxemia refers to toxins in the bloodstream that are carried beyond the site of infection

What pathogens cross the placenta?

Toxoplasma gondii, Treponema pallidum, and HIV

Virulence

Virulence is the degree of pathogenicity. The relative ability of a pathogen to infect a host and cause disease

Epidemiology

Branch of medical science concerned with the incidence, distribution, and control of diseases that affect large numbers of people.

Three ways pathogens can be transmitted

Contact transmission Vehicle transmission Vector transmission

Contamination

Contamination is the mere presence of microbes in or on the body

What are the three types of exotoxins?

Cytotoxins Neurotoxins Enterotoxins

Contagious Disease

a type of communicable disease that spreads quickly from person to person

Contact Transmission

the spread of pathogens from one host to another

Mortality

the state of being the subject of death

Symbiosis

to live together

Vehicle Transmission

transmission by an inanimate reservoir (food, water, air)

mechanical vector transmission

vectors body parts are contaminated with the infectious microbe which are passively brushed off and onto the host

Sporadic disease

when only a few scattered cases occur within an area or population

Fill in the Blank: Diseases that are naturally spread from their usual animal hosts to human are called ___________________________

zoonoses

What types of infections occur in health-care associated environments?

Nosomical infections -exogenous nosomical infections -endogenous nosomical infections -iatrogenic nosomical infections

Signs

Objective manifestations of disease observed or measured by others

What are opportunistic infections?

Opportunistic pathogens are normal microbiota that cause disease under certain circumstances

Pathogenicity

Pathogenicity is the ability of a microorganism to cause disease

Droplet Contact Transmission

Pathogens can be transmitted within droplet nuclei that exit the body during exhaling, coughing, and/or sneezing

Portals of exit

Portals of exit are where pathogens leave the host in order to infect others

Germ Theory of Disease

Proposed by Koch and Pasteur as a disease caused by infections of pathogenic microorganisms

What is a reservoir?

Reservoirs are sites where pathogens are maintained as a source of infection

Our microbiome includes all the microbes that live on and within us. These normal flora fall into two groups, resident and transient. What is the difference between these two groups?

Resident Microbiota are always present throughout a person's life Transient Microbiota are intermittently present (few hours, days, months before disappearing) throughout a person's life

What two groups compose our microbiome (normal flora)?

Resident microbiota and Transient microbiota

Two types of microbiota

Resident microbiota: always present Transient microbiota: intermittently present

By cell numbers, are we more human or more bacterial?

Scientists say it's more of a one-to-one scenario and that the people who say we are more bacterial than human regarding cell number is simply not true.

Syndrome

Symptoms and signs that characterize a disease or abnormal condition

What can result from infection of a fetus by pathogens in the womb?

The infection of a fetus by pathogens in the womb can result in spontaneous abortion, birth defects, or premature death

Infection

The invasion of the host by a pathogen

Morbidity

another reference to disease that refers to any change from the state of health

Fill in the Blank: Infections that may go unnoticed due to the absence of symptoms are called _____________ infections

asymptomatic or clinical

descriptive epidemiology

collection and analysis of data

An axenic environment is one that

contains only one species

A patient contracted athlete's foot after long-term use of a medication. His physician explained that the malady was directly related to his medication. Such infections are termed

endogenous infection

Fill in the Blank: The study where and when diseases occur and how they are transmitted within populations is ________________

epidemiology

Fill in the Blank: The study of the cause of disease is _______________________

etiology

What are the two types of toxins?

exotoxins and endotoxins

Fill in the Blank: Nonliving reservoirs of disease, such as a toothbrush, drinking glass, and needles are called ____________________________

fomites

Epidemic disease

happens wherever a disease occurs at a greater frequency than is usual for an area or population

Which of the following are most likely to cause disease?

highly virulent organisms

Which of the following is the correct sequence of events in infectious diseases?

incubation, prodromal period, illness, decline, convalescence IPPIDC

Nosomial infections

infections acquired by patients or health care workers while they are in health care facilities

Asymptomatic (subclinical)

infections lack symptoms but may still have signs of infection

Asymptomatic (subclinical) infections

infections that lack symptoms but may still have signs of infection

Descriptive Epidemiology

involves the careful tabulation of date concerning a disease. -records location and time of the case of disease -collects patient information -try to identify the index case of the disease

Airborne Transmission

involves the spread of pathogens farther than 1 m to the respiratory mucous membranes of a new host via aerosols

Cytotoxins

killl host cells in general or affect their function

types of vector transmission

mechanical and biological

Consider the following case. An animal was infected with a virus. A mosquito bit the animal, was contaminated with the virus, and proceeded to bite and infect a person. Which was the vector?

mosquito

opportunistic pathogens

normal microbiota that cause disease under certain circumstances

Fill in the Blank: ___________________ infections are those acquired by patients or staff while in health care facilities

nosocomial

Pandemic disease

occurs if an epidemic disease occurs simultaneously on more than one continent

Indirect Contact Transmission

occurs when pathogens are spread from one host to another by fomites example: contaminated needle

Fill in the Blank: A microbe that causes disease is called a _____________________

pathogen

biological vector transmission

pathogens are within the vector and transmission to the host is through a bite

Endogenous nosomical infections

pathogens arise from normal microbiota due to factors within the health care setting

Fill in the Blank: The total number of cases of a disease in a given area is its ________________________

prevalence

Direct Contact Transmission

requires close association between infected and susceptible host -example: touching, kissing

The most frequent portal of entry for pathogens is

respiratory tract

Disease

results if the invading pathogen alters normal body functions

Neurotoxins

specifically interfere with nerve cell function

Symptoms

subjective characteristics of disease felt only by the patient

Acute Disease

symptoms develop rapidly but the disease lasts only a short time

Virulence Factors

the degree of pathogenicity

Incidence

the number of NEW cases of a disease in a given area during a given period of time

Prevalence

the number of TOTAL cases of a disease in a given area during a given period of time

Virulence factors contribute to virulence through

-Adhesion factors -Biofilms -Extracellular enzymes -Toxins -Antiphagocytic factors

What are the terms used to classify infectious disease?

-acute disease -chronic disease -subacute disease -latent disease -communicable disease -contagious disease

What is the role of adhesion in infection?

-adhesion is the process by which microorganisms attach themselves to cells -required to successfully establish colonies within the host -uses adhesion factors such as specialized structures and attachment proteins

Vector Transmission

-vectors are animals that transmist diseases from one host to another -transmission of an infectious agent by an insect, arthropod, or animal

List three conditions that create opportunities for pathogens to become harmful in a human

1) gain access through the skin or portal of entry 2) attach to the host cell 3) evade the body's defense mechanisms long enough to become hazardous

Five categories of virulence

1. Adhesion 2. Biofilms 3. Extracellular enzymes 4. Toxins Antiphagocytic factors

Describe three modes of disease transmission

1. Direct contact 2. Airborne transmission 3. Vehicle transmission 4. Vector transmission

List the correct sequence the five stages of infectious diseases

1. Incubation Period 2. Prodromal Period 3. Illness 4. Decline 5. Convalescence

What are the five stages of infectious disease?

1. Incubation period 2. Prodromal period 3. Illness 4. Decline 5. Convalescence

List three portals through which pathogens enter the body

1. mucous membrane 2. skin 3. Parental route

What are the ways that diseases are classified?

1. the body system they affect 2. the effect they have on populations 3. their longevity and severity 4. how they spread to their host

Contrast iatrogenic and nosocomial diseases

Iatrogenic: direct result from modern medical procedures. Literally means "doctor induced" infections Nosomial: infections acquired by patients or health care workers while they are in health care facilities

innate immunity

Immunity that is present before exposure and effective from birth. Responds RAPIDLY to various pathogens including, parasitic worms, protozoa, fungi, bacteria, and viruses. Composed of the first two lines of defense that consists of external physical barriers like the skin and mucous membrane (1st) and of cells, bloodborne chemicals, and processes that inactive or kill invaders (2nd)

Waterborne Transmission

Important in the spread of many gastrointestinal diseases -Fecal-oral infection

Contrast the terms infection and morbidity

Infection: the invasion or colonization of the body by pathogenic microorganisms Morbidity: incidence of a specific notifiable disease

Which of the following is false concerning microbial contaminants?

Most microbial contaminants will eventually cause harm

In which type of symbiosis do both members benefit from their interaction?

Mutualism

List three types of symbiotic relationships and give an example of each

Mutualism Commensalism Parasitism Ammensalism

4 types of symbiosis

Mutualism: both species benefit Commensalism: one benefits; one unaffected Amensalism: one killed while the other is unharmed Parasitism: one benefits; one harmed

Etiology

The study of the cause of the disease

Our microflora varies by body site. The microflora of our skin is markedly different from that of our upper digestive tract. Why?

They are marked differently from each other because they are at different stages during the development of the baby in the womb.

Chronic Disease

a disease that develops gradually and continues over a long period of time

Which of the following phrases describes a contagious disease?

a disease that is easily passed from host to host in aerosols

Subacute Disease

a disease that is intermediate between acute and chronic

Endemic disease

a disease that normally occurs continually at a relatively stable incidence to the population or region

The process by which microorganisms attach themselves to cells is

adhesion

Enterotoxins

affect cells lining the gastrointestinal tract

The nature of bacterial capsules

affects the virulence of these bacteria

Types of vehicle transmission

airborne, waterborne, foodborne

Which of the following types of epidemiologists is most like a detective?

an analytical epidemiology

analytical epidemiology

analyzes a particular disease in detail to determine its probable cause

When pathogenic bacterial cells lost the ability to make adhesions, they typically

become avirulent

experimental epidemiology

begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people -Koch's postulates

Fill in the Blank: An animal that carries a pathogen and also serves as host for the pathogen is a __________________ vector

biological

Latent Disease

causative agent is inactive for a time but then activates and produces symptoms

Exogenous nosomical infections

caused by pathogens acquired from a health care environment

Coagulase

causes blood proteins to clot, providing a "hiding place" for bacteria within a clot

Toxins

chemicals that harm tissues or trigger host immune responses that cause damage

Collagenase

degrade specific molecules to enable bacteria to invade deeper tissue -breaks down collagen

Hyaluronidase

degrade specific molecules to enable bacteria to invade deeper tissue -digests hyaluronic acid, the "glue" that holds animal cells together

Kinase

digests blood clots, allowing subsequent invasion of damaged tissue

Iatrogenic nosomical infections

direct result from modern medical procedures. Literally means "doctor induced" infections

Types of contact transmission

direct, indirect, droplet

Leukocidins

directly destroy phagocytic white blood cells