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
