8.1 Infection Control Flashcards
are living organisms that are too small to be seen with the naked eye
Microorganisms
Microorganisms categories
Bacteria, viruses, protozoa, prions, and fungi
Microorganisms that live on or inside the body without causing infections or diseases are referred to as ______
normal microbial flora
Microorganisms that cause infections and diseases are called _____
pathogens
are very small, single-cell organisms with a cell wall and an atypical nucleus that lacks a membrane
Bacteria
is essential for survival of the bacterium, making it the target for destruction by some antibiotics
cell wall
grow independently and can replicate without a host cell
Bacteria
Bacteria are classified according to shape, and most have one of three distinct shapes:
spherical, rod-shaped, spiral
spherical bacteria
cocci
rod-shaped bacteria
bacilli
spiral bacteria
spirilla or spirochetes
By using staining process, bacteria can be sub-classified as ______, and as ______
Gram-positive or Gram-negative,
acid-fast or nonacid-fast
The bacteria is identified as ______ if they retain the dye when treated with alcohol
Gram-positive
if the alcohol washes out the dye, they are called _____
Gram-negative
The bacteria are stained, heated, and treated with an acid alcohol to remove the color. If the bacterium resists decolorization, it is classified as ______
acid-fast positive
The bacteria are stained, heated, and treated with an acid alcohol to remove the color. If decolorization occurs, the bacterium is _____
acid-fast negative
examples of Gram-positive
Streptococci and staphylococci
example of Gram-negative
Escherichia coli, a bacillus
example of acid-fast positive or simply called “acid fast”
Mycobacterium tuberculosis, a bacillus
require oxygen to grow
Obligate aerobes
will not grow in presence of oxygen
anaerobes
Bacteria that can adapt and grow under either aerobic or anaerobic conditions are called ______
facultative organisms
are resistant to destruction and can remain viable for many years, often being carried through the atmosphere on virtually invisible dust particles
Endospores
Significant diseases caused by bacteria include:
- tuberculosis caused by M. tuberculosis,
- streptococcal pharyngitis (Strep throat) and necrotizing fasciitis (flesh-eating bacteria), both of which are cause by streptococcal Group A, and
- Infectious diarrhea and hemolytic uremic syndrome, both of which are caused by E. coli
Are smaller than most bacteria and are just barely visible in an ordinary microscope
Rickettsiae
Their most significant identifying feature is that they only grow inside animal cells
rabbits and rats (Rickettsiae)
Do not survive in the environment and are transmitted among animals by infected arthropod vector bites
ticks, lice, fleas, and mites (Rickettsiae)
are only accidental hosts for Rickettsiae
Humans
are causative agents for Rocky Mountain spotted fever and typhus fever
Rickettsiae
Are subcellular organisms and are among the smallest know disease-causing organisms
Viruses
Because of their small size, they must be viewed with an electron microscope
Viruses
A fully developed viral particle, called a ____, is made up of genetic material, deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), which is protected by an outer protein coating called the ____
virion,
capsid
may be covered by a lipoprotein envelope that has projecting spikes
capsid
Enveloped viruses examples
influenza, human immunodeficiency virus (HIV), and hepatitis B.
cause common cold, and lack both the envelope and spikes
Rhinoviruses
causes infectious mononucleosis
Epstein-Barr virus
causes chicken pox and herpes zoster (shingles)
varicella (Virus)
Occur as single-celled yeasts or as long, branched, filament-like structures called molds that are composed of many cells
Fungi
Yeasts reproduce by
forming buds
molds reproduce by
spore formation
Fungi cause skin infections, such as
athlete’s foot and ringworm
Fungi causes respiratory infections, such as
histoplasmosis and coccidioidomycosis
Fungi causes opportunistic infections such as
Pneumocystis carinii pneumonia (PCP)
causes pharyngeal and esophageal candidiasis in individuals with compromised immune systems
Fungi
infections caused by usually nonpathogenic organisms
opportunistic infections
The smallest and least understood of all microbes
Prions
Scientists believe that they may be infectious proteins
Prions
They do not have DNA or RNA, but they are capable of automatically transforming health proteins in nerve cells into more of them
Prions
are resistant to the body’s natural defenses and can continue to multiply unchecked, causing irreversible neurologic damage
Prions
They were first identified as the cause of scrapie
Prions
a degenerative disease affecting the nervous systems of sheep
scrapie
mad cow disease
bovine spongiform encephalopathy
are the cause of bovine spongiform encephalopathy
Prions
are the cause of both classic and variant Creutzfeldt-Jakob disease in humans
Prions
may related to other conditions characterized by slow deterioration of the nervous system
Creutzfeldt-Jakob disease
cause sponge-like changes in the brain with progressive dementia
classic and variant Creutzfeldt-Jakob disease
Are complex single-celled animals that generally exists as free-living organisms
Protozoa
a few are parasitic and live within the human body
Protozoa
They may be classified as motile (moving) or nonmotile
Protozoa
Protozoa are further classified by their method of motility, some move by changing their shape to form _____
pseudopods (false “feet”)
Protozoa also move using:
flagella,
cilia
whiplike formations that move the cell
flagella
fine, hairlike projections that propel the organism
cilia
Protozoa can infect the
gastrointestinal, genitourinary, respiratory, and circulatory systems
Common protozoal diseases include:
- Amebiasis and giardiasis
- Trichomoniasis
- Toxoplasmosis
a sexually transmitted disease affecting the male and female genitourinary tracts
Trichomoniasis
both affect the gastrointestinal tract and cause diarrhea
Amebiasis and giardiasis
it causes a greenish-yellow discharge from the male urethra and from the vagina in the female
Trichomoniasis
is contracted from contact with cat feces or eating undercooked meat containing the protozoan
Toxoplasmosis
affects the blood and lymphatic vessels and can cause congenital infection in a fetus or neurological impairment in the immunocompromised
Toxoplasmosis
The factors involved in the spread of disease
cycle of infection
The Cycle of infection
- Portal of entry
- Susceptible host
- Pathogenic organism
- Reservoir of infection
- Portal of exit
- Means of transmission
Microorganisms capable of causing disease are called
pathogenic organisms or pathogens
Infectious Organisms possess certain properties called ______ that distinguish them from nonpathogenic organisms or normal flora
virulence factors
Bacterial pathogens have an affinity for a certain type of cell in the body and attach to these cells, excreting protein substances called ____ that can kill or injure the host cells
toxins
The pathogens that cause ________ have these virulence factors
diphtheria, pertussis, typhoid fever, and dysentery
These factors enable bacteria to destroy or damage host cells and resist destruction by the host’s cellular defense
virulence factors
Most parasitic protozoa produce
some type of resistant form, such as a ____, to survive
in the environment outside the host
cyst
Normal flora are capable of causing disease:
- when they are not confined to their usual environment,
- when an individual’s resistance is weakened, or
- when broad-spectrum antibiotics disrupt the ecological balance of the resident flora
a normal flora of gastrointestinal tract, can become pathogenic if it enters the bladder
E. coli
may be found in the throat or gastrointestinal tract of many healthy persons
Candida albicans
yet this same organism can assume a pathogenic role, causing vaginal infections in females when competing bacteria are destroyed by antibiotic treatment
Candida albicans
is an opportunistic organism that proliferates when immunity is compromised, causing both esophagitis and respiratory infections in patients with acquired immunodeficiency syndrome (AIDS).
Candida
may be any place where pathogens can thrive in sufficient numbers to pose a threat
reservoir or source of infection
Such an environment must provide moisture, nutrients, and a suitable temperature, all of which are found in the human body
reservoir or source of infection
might be a patient with hepatitis, a radiographer with an upper respiratory infection, or a visitor with staphylococcal boils
reservoir or source of infection
Other examples of non-human reservoirs and infections include:
- Animals, the reservoir for salmonella infections;
- Soil, the reservoir for tetanus; and
- Water, the reservoir for Legionnaires’ disease.
may be any route through which blood, body fluids, excretions, or secretions leave the body
Portal of exit
Examples include Respiratory, urinary, and gastrointestinal tracts; an infected wound; and the bloodstream
Portal of exit
Are frequently patients who have reduced natural resistance to infection.
Susceptible Host
They may develop aa nosocomial infection
Susceptible Host
hospital-acquired infection
nosocomial infection
Hospital infections also pose a threat to health care workers. When contracted by HCW, these infections are called _______ acquired rather than nosocomial infections
occupationally
are spread by blood and blood products
Hepatitis B and C viruses
Is the route by which microorganisms gain access into the susceptible host
Portal of Entry
examples include Respiratory, urinary, and gastrointestinal tracts; an open wound or break in the skin; the mucous membranes of the eyes, nose, or mouth; and the bloodstream
Portal of Entry
The most direct way to intervene in the cycle of infection is to prevent the ______ of the infectious organism from the reservoir to the susceptible host
transmission
This transmission mode requires that the host is touched by an infected person and the organisms are placed in direct contact with susceptible host
direct contact
The five other principal routes of transmission are
indirect
Indirect transmission involve transport of organisms by way of
fomites, vectors, vehicles, airborne means, droplet contamination
