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infection
infection
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Pathology
12/27/2010

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Term
prokaryotic cells
Definition
Cells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei). These cells have few internal structures that are distinguishable under a microscope. Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae) are prokaryotes.


Bacteria perform many important functions on earth. They serve as decomposers, agents of fermentation, and play an important role in our own digestive system. Also, bacteria are involved in many nutrient cycles such as the nitrogen cycle, which restores nitrate into the soil for plants. Unlike eukaryotic cells that depend on oxygen for their metabolism, prokaryotic cells enjoy a diverse array of metabolic functions. For example, some bacteria use sulfur instead of oxygen in their metabolism.
(Daniel Kunkel)
Term
eukaryotic cells
Definition
The most noticeable feature that differentiates these more complex cells from prokaryotes is the presence of a nucleus, a double membrane-bound control center separating the genetic material, DNA (deoxyribonucleic acid), from the rest of the cell.

In addition to the plasma membrane, eukaryotic cells contain internal membrane-bound structures called organelles. Organelles, such as mitochondria and chloroplasts, are both believed to have evolved from prokaryotes that began living symbiotically within eukaryotic cells. These vital organelles are involved in metabolism and energy conversion within the cell. Other cellular organelles within eukaryotic cell structure carry out the many additional functions required for the cell to survive, thrive, grow and reproduce.

Eukaryotic cells can reproduce in one of several ways, including meiosis (sexual reproduction) and mitosis (cell division producing identical daughter cells).



Read more at Suite101: Prokaryotic and Eukaryotic Cells: The Difference between Prokaryotes and Eukaryotes http://www.suite101.com/content/prokaryotic-and-eukaryotic-cells-a32332#ixzz19JzDw0Fl
Term
pathogens
Definition
disease causing microbes often referred to as "germs"
Term
germ theory
Definition
resulted from studying fermentation and spoilage of foods. The transmission of pathogens and infection through hands, surfaces, water and the air was documented, and the practices of asepsis were begun
Term
culture
Definition
growth of microorganisms on a specific nutritious medium in a laboratory
Term
Bacteria
Definition
unicellular organisms that do not require living tissue to survive. They vary in size and shape and are classified and named accordingly.


Unicellular
Cell wall—gram – or gram +
Classified by size & shape
Bacilli—rod shaped
Spirals
Cocci—spherical
Streptococci
Staphylococci
Term
major groups of bacteria
Definition
bacilli
spirals
cocci
Term
bacilli
Definition
rod shaped organisms. EX: Clostridium tetani, the microbe causing tetanus or "lockjaw". The microbe survives as a spore in the soil and contaminates puncture wounds. A toxin from the bacterium causes seizures and muscle spasms and, eventually , respiratory failure.
Term
Spirals
Definition
bacteria which include spirochetes and vibrios. EX: Treponema pallidum, the cause of syphilis and Borrelia burgdorferi, the agent causing lyme disease.
Term
Cocci
Definition
spherical formed bacteria. Further categorized by their characteristic groupings:
diplococci are pairs of spherical bacteria - pneumococcus
streptococci-chains frequently causing respiratory infections
staphylococci are clusters -staphylococcus aureus, a cause of skin infections.
Term
basic bacteria structure
Definition
outer rigid cell wall protects the microbe and provides a specific shape
cell walls are either gram neg or gram pos.-gram stain determines which
human cells do not have cell walls. So medications that act on the particular cell wall won't damage human cells.

cell membrane-inside cell wall. This semi permeable membrane selectively controls movement of nutrients and other materials in an out of the cell. Metabolic processes also take place in the cell membrane

external capsule or slime layer is found on some.
this layer is outside the cell wall and offers additional protection to the organism-it also interferes with phagocytosis and WBCs in the human body

flagellae attached to the cell wall for mobility

Pili or Fimbriae hairlike structures found on some bacteria

cytoplasm containing chromosomal DNA and RNA

Some secrete toxins
Term
toxins
Definition
exotoxins -usually by gram positive bacteria and diffuse through body fluids. Produce an antitoxin or antibody reaction by the immune system

neurotoxin and enterotoxins included in this class.

endotoxins-present in the cell wall of gram negative organisms and are released after the bacterium die. may cause fever and general weakness or may have serious effects on the circulatory system causing endotoxic shock.

Enzymes-produced by some bacteria and are a source of damage to the host tissues or cells. Other enzymes assist the bacteria to invade tissue by breaking down components.

spores- a latent form of the bacterium with a coating that is highly resistant to heat and other adverse conditions. (tetanus and botulism)
Term
binary fission
Definition
process of bacteria replication
a division of the cell produces two daughter cells identical to the parent bacterium.
Term
differences between bacteria and human cells
Definition
bacteria have a cell wall and human cells do not
bacteria have flagella for movement
bacterial cells contain a ring of DNA and not a defined nucleus containing chromosomes
bacteria do not contain membrane bound organelles
bacteria are much smaller than human cells
Term
virus
Definition
very small obligate intracellular parasite that requires a living host cell for replication.
They can hide inside human cells and they lack their own metabolic processes or structures that might be attacked by drugs.


Very small obligate parasite that requires a host for replication
Viral DNA (most) or RNA
Protein coat or capsid
Term
virion
Definition
extracellular virus particle. Consists of a protein coat or capsid and a core of either DNA or RNA. The protein coat comes in many shapes and sizes and undergoes change relatively quickly in the evolution of the virions.
Term
chlamydiae, rickettsiae and mycoplasmas
Definition
microorganisms that have some similarities with both bacteria and viruses. The replicate by binary fission (bacteria) but they lack some basic component; therefore they require the presence of living cells for reproduction.
Term
fungi
Definition
grow everywhere
eukaryotic
growth promoted by warmth and moisture
reproduce by budding spores and extend hyphae
cell wall
only a few are pathogenic
Term
protozoa
Definition
eukaryotic
unicellular
motile
lack cell wall
occur in a number of shapes
pathogens are usually parasites
EX: malaria-mosquito
includes amebas
Term
helminths
Definition
worms-not microorganisms
parasites and cause infections in humans
mulitcellular
eukaryotic
three stage lifecycle-egg, larva and adult
found in the intestine but can inhabit the lung or blood vessels during parts of their life cycle
Term
prions
Definition
protein-like agents that are transmitted by consumption of contaminated tissues or the use of donor tissues contaminated with the protein.
It induces proteins within the brain of the recipient to undergo abnormal folding and change of shape-fatal.
Term
areas of the body that lack flora
Definition
should be sterile and free of flora(microorganisms)
lungs
bladder
stomach
blood
cerebrospinal fluid
uterus, fallopian tubes, ovary
kidney
Term
infection
Definition
occurs when a microbe or parasite is able to reproduce in or on the body's tissues.
Term
endemic
Definition
consistently occurring in a particular population.
always present in a particular region
Term
epidemic
Definition
a disease occurring in higher numbers than usual in certain population within a given time period
Term
reservoir
Definition
source of infection -can be infected person, food source or animal.
Term
modes of transport from reservoir to new host
Definition
direct
indirect-contaminated food or hand, inanimate objects
droplet-oral or respiratory
aerosol-small particles from the respiratory tract remain suspended in the air
vector-borne-insect or animal
Term
nosocomial
Definition
an infection acquired while in the hospital
UTIs most common
Term
interferons
Definition
proteins produced by human host cells in response to viral invasion of the cell. They influence the activity of nearby host cells, increasing their resistance to viral invasion and interfering with viral replication.
Term
factors affecting resistance
Definition
age
genetic susceptibility
immunodeficiency of any type
malnutrition
chronic disease
stress
inflammation or trauma affecting barriers
impaired inflammatory response (ex, long term glucocorticoid use)
Term
pathogenicity
Definition
refers to the capacity of microbes to cause disease
Term
virulence
Definition
degree of pathogenicity of a specific microbe based on:
invasive qualities
toxic qualities
adherence to tissue by pili, fimbriae or a specific membrane receptor sites
ability to avoid host defenses(mutation)
Term
case fatality rate
Definition
percentage of deaths occurring in the number of persons who develop the disease
Term
where to find information on the latest diseases
Definition
morbidity and mortality weekly report (CDC)
Term
universal precautions
Definition
provide the basic guidelines by which all blood, body fluids and wastes are considered "infected" in any client regardless of the client's apparent condition.
two levels
general
specific to known infections at specific sites
Term
sterilization
Definition
removal of all microorganisms
exposure to heat using several methods including autoclaving
time packing and temperature are critical
Term
autoclave
Definition
an appliance to sterilize instruments or materials with steam at high temperature and pressure
Term
disinfectants
Definition
chemical solutions that are known to destroy microorganisms or their toxins on inanimate objects.
Few destroy spores-read directions
glutaraldehyde -most effective
Term
antiseptics
Definition
chemicals applied to the skin that do not usually cause tissue damage, such as isopropyl alcohol -70%-active ingredient in hand sanitizers
reduce number but do not destroy all microorganisms
Term
incubation period
Definition
refers to the time between entry of the organism into the body and appearance of clinical signs of the disease.
Vary considerably
during this time the organisms reproduce until there are sufficient numbers to cause adverse effects on the body
Term
prodromal period
Definition
the time when the infected person may feel fatigued, lose appetite or have a headache and usually senses that "I am coming down with something"
Term
acute period
Definition
infectious disease develops fully and the clinical manifestations reach a peak. The onset of a specific infection may be insidious with a prolonged prodromal period or sudden or acute with the clinical signs appearing quickly with severe manifestations
Term
acute period is dependent upon?
Definition
depends on the virulence of the particular pathogen and host resistance
Term
convalescent period
Definition
recovery period when signs subside and body processes return to normal.
Term
subclinical infection
Definition
microbe reproduces within the body but does not cause signs or symptoms
Term
septicemia
Definition
situation in which the pathogens are circulating and reproducing in the blood, affecting all systems and threatening life. An overwhelming systemic infection.
Term
localized signs
Definition
those of inflammation
heat
pain
swelling redness

lymphadenopathy
exudate, purulent
Term
systemic signs
Definition
fever
leukocytosis
elevated ESR
fatigue, weakness, anorexia
headache, arthralgia
Term
sign of bacterial infection
Definition
purulent exudate or pus
leukocytosis (increased WBC count)
Term
sign of viral infection
Definition
serous, clear exudates
leukopenia (reduction in WBCs count)
Term
lymphadenopathy
Definition
swollen and tender lymph nodes
Term
monocytosis
Definition
increase in monocytes
seen in chronic infections
Term
neutropenia
Definition
reduction in neutrophils
Term
indicator of inflammation in the blood
Definition
c-reactive protein and erythrocyte sedimentation rate elevated (ECR)
Term
guidelines for effective drug therapy
Definition
1. drug should be taken at regular intervals over 24 hours to maintain blood levels
2. antimicrobial drugs should be taken until the medication is used up
3. respect to taking with or without food
4. best to identify specific organism and choose most effective antibiotic with least effect on good flora
5. drug allergies taken into consideration
6. antivirals just inhibit production but do not kill virus
antibacterial agents do not work on viruses
Term
antibacterial drugs
Definition
acts in one of four ways
1. interference with bacterial cell wall synthesis. Safe because human cells lack cell walls ex: penicillin
2. increase the permeability of the bacterial cell membrane, allowing leakage of bacterial cell contents
3. interfere with protein synthesis and cell reproduction. These have effects on fetus and young child.
4. interfere with the synthesis of essential metabolites.
Term
problem with antibacterial drugs
Definition
allergic reaction
mild and severe and digestive problems
secondary infections may occur due to a wiping out of good flora or an imbalance of flora
Term
antivirus agents
Definition
decrease the reproduction of viruses inside the host cell but cannot destroy the virus.
control but do not cure.
some are only effective against actively replicating viruses
tend to have adverse effects on the host because they alter viral interaction within the host cell
Term
antifungal agents
Definition
interfere with mitosis in fungi or may increase fungal membrane permeability.Most are topical (athletes foot)
Term
influenza
Definition
Term
RNA virus
Definition
Most of them replicate in the cytoplasm. They don’t require as much polymerases of their host to replicate as DNA viruses do. Examples of human diseases caused by RNA viruses are SARS, influenza, hepatitis C, etc.

RNA viruses genetic information is stored, as their name suggests, in RNA, not DNA. This has important consequences in the life cycle of the virus - and gives it the potential to outwit the immune system.
makes frequent mistakes during copying - averaging one mistake per 10,000 nucleotides each time it is copied, and has less of an ability to correct errors. Since in normal cells RNA molecules are not "blueprint" quality, the host cell does not check copied RNA as carefully as it does DNA to assure that it is free of errors. These properties make RNA very poorly suited for the storage of information - which explains why all other organisms use it only as a temporary messenger molecule.

However, these very properties make RNA ideal for the storage of viral information. Once the immune system has learned to recognize an infecting virus and create antibodies against it (developed an immunity), it can quickly destroy it, so the virus can no longer use that host for reproduction. In order to reinfect that host - it must first change its nature enough that the immune system will no longer recognize it. In other words, it must mutate.

The unstable nature of the RNA molecule provides this mutagenic factor, allowing RNA viruses to evolve far more rapidly than DNA viruses, frequently changing their surface structures. These mutations make it more difficult for an organism to develop any kind of lasting immunity to the virus.
Term
disease causing pathogens
Definition
Bacteria
Viruses
Chlamydiae, rickettsiae, & mycoplasma
Fungi
Protozoa
Helminths
Prions
Term
chlamydiae
Definition
Exist in two forms:
Elementary body-infectious form
Reticulate body-noninfectious form that uses the host to replicate to become elementary bodies
Chlaymydial infection is a STD that causes PID. PID may affect the infant born to the mother.
Term
rickettsiae
Definition
Gram negative bacteria that reside w/in the host & are transmitted through an insect vector such as lice or ticks.
Ex—rocky mountain spotted fever
Term
mycoplasma
Definition
Smallest cellular microbe that is a common cause of pneumonia.
Term
fungi
Definition
Found everywhere. Like to live on dead organic material. “Don’t pick that up, you don’t know where it has been!”
Few fungi are pathogenic
Tinea pedis (athlete's foot)
Candida—harmless fungi that may cause problems in immunosuppressed patients
Term
protozoa
Definition
Eukaryotic unicellular & motile

Pathogens are usually parasites
Trichomonas
Plasmodium
Entamoeba histolytica
Term
helminths and prions
Definition
Worms!

Abnormal molecule that is transmitted through the blood of animals or humans

Term
transmission of pathogens
Definition
Direct contact: person to person
Indirect contact: intermediary object
Droplet to oral or respiratory system
Vector-borne: insect or animal intermediary
Term
host resistance
Definition
Healthy individuals usually are resistant to infection
Interferons: produced by cells in response to viruses that make nearby cells more resistant
Factors that decrease resistance
Age
Genetic disposition
Immunodeficiency
Malnutrition
Chronic disease
Stress
Inflammation or trauma affecting skin or mucosa
Poor inflammatory response
May need prophylactic medications
Term
control of transmission
Definition
Universal precautions
Hand washing
Cover mouth when coughing or sneezing
Good hygiene
Avoid sick people
Safe water and food supplies
Block portal of entry
Sterilization: heat & autoclave
Disinfectants: chemicals that destroy pathogens
Antiseptics: disinfectants that go directly on skin
Term
onset and course of infections
Definition
Incubation period: time between entry into body and clinical signs of disease
Prodromal period: early infection period when signs are nonspecific
Insidious: long prodromal period
Acute period: infection develops fully
Recovery or convalescent period
Chronic infection
Septicemia: becomes systemic through bloodstream
Term
signs and symptoms
Definition
Local signs
Inflammation
Pain
Tenderness
Redness
Pus or serous exudates

Systemic signs
Fever
Fatigue
Weakness
Cognitive involvement