Chapter 14 Micro Flashcards
what is a pathogen?
disease causing microorganism
Infection means what?
colonization of the body by pathogens
disease
abnormal state which the body is not functioning normally
what is pathogenesis?
development of the disease
etiology can be defined as what?
the cause of a disease
Few microorganisms are pathogenic. True or false?
TRUE!
what is the importance of normal microbiota?
permanently colonize the host starting at birth and later through food and contact with others
how are microbiota studied and what is the benefit?
DNA sequencing to make microbiome.
Determining microbiome can help with specific syndrome or disease correlation
why might different types of bacteria colonize different parts of the body?
- Nutrient availability (secretion, excretions and dead cells
- physical and chemical factors (pH and temp)
- defenses of the host
- mechanical factors (chewing, flushing, mucus and cilia)
what are transient microbiota?
only present for a short period of time, typically coming from the environment and do not cause disease.
when can transient microbiota cause disease?
when it displaces the normal microbiota
list some factors that contribute to differing microbiota in each person:
age diet stress climate lifestyle occupation emotional state health status
where does normal microbiota reside?
skin conjunctiva nose throat mouth large intestine urinary tract reproductive system
normal microbiota of the skin:
most microbes do not become direct residents due to oil and sweat on skin’s surface. low moisture content
what is keratin’s role in the normal microbiota?
serves as barrier; low pH of skin inhibits many microbes
normal microbiota of conjunctiva:
contains nearly the same microbiota found on the skin’s surface
what are some defenses of the conjunctiva to prevent microbe colonization?
tears and blinking
normal microbiota of nose and throat:
microbial antagonism reduces potential pathogens from causing disease
what are some defenses of the nose and throat to prevent colonization?
nasal secretions kill and inhibit many microbes
mucus and ciliary action remove microbes
normal microbiota of the mouth:
moisture, warmth and constant presence of food make the mouth an ideal environment that supports large diverse microbial populations
what are some defenses of the mouth?
biting, chewing, tongue movements and salivary flow dislodge microbes
normal microbiota of the urinary and reproductive systems:
mucus and shedding of the lining prevent microbes from attaching
Flow removes microbes
cilia and mucus expel microbes from the cervix
what are defenses of the urinary and reproductive tract to prevent microbe colonization?
- acidity of the vagina inhibits or kills microbes
- urea and low pH of urine are antimicrobial
normal microbiota of the large intestine:
contains largest numbers of the resident microbiota in the body because of moisture and nutrients
what are defenses of the large intestine to prevent microbe colonization?
- mucus and regular shedding of the lining prevent many microbes from attaching to the lining of the GI tract
- mucosa produces several antimicrobial chemicals
microbial anatogonism
competition between microbes
how does the normal microbiota use microbial antagonism?
competing for nutrients
producing substances harmful to invaders
changing conditions such as pH and O2
explain germ free animals
raised in lab but have underdeveloped immune systems and are more susceptible to pathogenic infection
require more calories and vitamins than normal animals
what happens when germ free animals are repopulated with microbiota from obese animals?
they become obese
why are germ free animals used?
help investigate host microbe interactions that promote health
PRObiotics are described as what?
live microbes that are applied or ingested to the body for beneficial effects
PREbiotics are describes as what?
chemicals that selectively promote growth of beneficial bacteria
what is the purpose for the FMT (fecal microbiota transplant)?
process of transplantation of fecal bacteria from healthy donor to recipient, can help with C. diff
What are the three types of symbiosis?
commensalism, mutualism, parasitism
what is commensalism?
one organism benefits and the other is unaffected
Example: S. epidermia inhabit surface on skin
what is mutualism?
both organisms are benefiting
Example: E.coli: bacteria in the large intestine that synthesizes vitamin K and some B vitamins; they’re absorbed into the bloodstream and distributed for use by body cells. In exchange, the large intestine provides nutrients used by the bacteria, allowing them to survive
what is parasitism?
one organisms benefits at the expense of the other like pathogens
Example: influenza
opportunistic pathogens are what?
when pathogens that normally inhabit other areas gain access to other body sites it can be detrimental in immunocompromised people
what are the three ways normal microbiota protect the host?
- occupy niches that pathogens might occupy
- lower ph by producing acids
- produce bacteriocins that kill other bacteria
what does etiology mean?
the cause of diseases or conditions
what are Koch’s postulates?
- same pathogen must be present in every case of the disease
- pathogen must be isolated from the diseases host and grown in pure culture
- pathogen from pure culture must cause the disease when it is inoculated into healthy lab animal
- pathogen must be isolated from inoculated animal and must be shown to the original animal
why is paying attention to Koch’s postulates important?
correlation does not mean causation
what are some problems with Koch’s postulates?
- some organisms cannot be cultured on artificial media
- some diseases types can be caused by multiple different pathogens
- some pathogens cause multiple diseases
- some carriers are asymptomatic
- some pathogens cause symptoms or leave tell tale signs that no other pathogen can produce, implicating it in the disease
what are the 3 ways to classify infectious diseases?
- signs and symptoms
- syndromes
- contagious, communicable, noncommunicable
what is a symptom?
change in body function that is felt by patient as a result of disease
Example is malaise
what is a sign?
change in body that can be measured or observed as result of disease, swelling, fever or paralysis
Examples is high cholesterol
what is syndrome?
specific group of signs and symptoms that accompany a disease
Examples: down syndrome, Parkinson’s syndrome, AIDS
contagious disease is classified as what?
disease that is easily spread from one host to another , does not require close contact
communicable disease is classified as what?
disease that is spread from one host to another either directly or indirectly, requires close contact
noncommunicable disease is classified as what?
disease that is not transmitted from one host to the other
give examples of contagious disease:
Influenza, measles, common cold
give examples of communicable disease:
ebola, HIV/AIDS, hepatitis
give examples of noncommunicable disease:
tetanus, food poisoning, lyme disease
COVID-19 is both:
contagious and communicable
what is incidence?
number of new cases of a disease over specific time period
what is prevalence?
existing cases of new disease at a given time
incidence x time) -(deaths +cures
what is sporadic disease?
disease that occurs occ. in pop
what is endemic disease?
disease constantly present in population
what is epidemic disease?
disease acquired by many hosts in given area in short time
what is pandemic disease?
worldwide disease (COVID, Influenza in 1918)
herd immunity
when many people in pop. are immune, others are protected from the spread of infection as consequence
what is acute disease?
symptoms develop rapidly, lasts short time
example: flu
what is chronic disease?
disease develops slowly and continues or recurs for a long time
example: encephalitis
what is subacute disease?
symptoms between acute and chronic
example: hepatitis
what is latent disease?
disease with period of no symptoms when the causative agents inactive
example: herpes
Covid-19 is an acute disease…
symptoms develop rapidly and last a short time
what is local infection?
pathogens that are limited to a small area of the body
what is systemic infection?
infection throughout the body via blood or lymph system
what is a focal infection?
infection that began as an asymptomatic infection in one place and causes distant injury to another part
what is focal infection theory?
distant from infections that spread from one place to another because infection is known and symptomatic
what is bacteremia?
bacteria in the blood
Example: can arise from teeth brushing and dental work
what is septicemia?
growth of bacteria in the blood
what is sepsis?
toxic inflammatory condition arising from spread of microbes, especially bacteria or their toxins from focus infection
what is toxemia?
toxins in the blood
what is viremia?
viruses in the blood
what is a primary infection?
acute infection that causes the initial illness
what is a secondary infection?
opportunistic infection that occurs after a primary infection. It may be a result of the primary infection or the treatment of the primary infection
what is a subclinical or asymptomatic disease?
no noticeable signs or symptoms (inapparent infection)
what is case fatality rate?
is the ratio of deaths to the total number of cases of a specific disease for a certain period of time
what are some general disease susceptibility factors?
climate nutrition lifestyle age sex fatigue inherited traits chemotherapy
what is incubation period?
Interval between infection and signs or symptoms, able to spread infection
In covid: 4-14 days
what is prodromal period?
early, mild symptoms
In COVID: fever, loss of smell/taste, headache
what is period of illness?
most severe, death possible, (white cells can go up or down)
In COVID: ICU admission, death possible
period of decline means what?
getting better, vulnerable to secondary infections
period of convalescence is what?
return to normal health, spread of infection still possible
what are reservoirs?
Continual sources of infection
Pathogen has resources for survival and opportunity for transmission
*can be living or nonliving
what is zoonoses?
diseases transmitted by animals to humans
what are infected individuals?
carrier signs and symptoms of disease as a human reservoir
what are carriers?
inapparent infections or latent diseases
what are different types of transmission?
contact transmission, vehicle transmission, vector transmission
what is waterborne transmission?
transmission by inanimate reservoir i.e water
sewage in H20 cholera
what is vehicle transmission?
transmission by inanimate reservoir
what is food-borne transmission?
transmission by an inanimate reservoir
incomplete cooking or storage of food leading to contagion
what is airborne transmission?
transmission by inanimate reservoir
must be through air more than one meter away
how can a person have transmission by zoonoses?
direct by animal-animal
contact with animal products
contaminated non living objects
ingestion
what is direct transmission?
requires close association between infected and susceptible host
what is indirect transmission?
spread by non living objects like fomites
what are droplets?
transmission by proximity to large infectious agent containing droplets less than 1 meter away
what is biological transmission?
active, pathogen reproduces in vector
what is mechanical transmission?
passive, arthropod carries pathogen on feet or body
what are nosocomial infections?
acquired in the hospital
what are some contributing factors to nosocomial infections?
compromised host, disease, wounds, burns, sedation, chemotherapy, stress, malnutrition
how can nosocomial infections be controlled?
aseptic technique, hand washing, disinfection, sterilization, packaging or equipment, dressings
what are emerging infectious diseases?
diseases that are new, increasing in incidence or showing potential
factors that contribute to EID include?
mutation, reassortment,
evolution of new strains, changes in weather, ecological disaster, war, poverty, inappropriate use of pesticides or antibiotics
what are the different types of epidemiology?
descriptive: collection and analysis of data done retrospectively
Example: Snow, London cholera epidemic
analytical: comparison of diseases group and healthy group
Example: Nightingale comparing soldiers and civilians
experimental: controlled experiments
Ex: “Savior of mothers” Ignatz Sem.
what are case reporting and nationally notifiable diseases?
health care workers report specified disease to local, state and national offices
Physicians are required to report occurrence
what is morbidity?
incidence of specific notifiable disease
mortality
deaths from notifiable disease
morbidity rate
number of people affected in relation to total pop
mortality rate
number of deaths from disease in relation to pop
why do nosocomial infections generate?
-microorganisms in the hospital environment
-the compromised (or weakened) status of the host
-the chain of transmission in the hospital
The interaction of all 3 factors poses a risk of HAI, not just one alone
