Flashcards in Ch. 4: Infectious Disease Deck (131):
approximately ( ) people have been infected at one time or another by hep B virus
2 billion people (~30% world population)
of the 2 billion people affected by hep b virus, about ( ) remain chronically infected and are carriers of the virus
350 million (~5% of world pop)
the normal or expected rate of infection in a population or geograchpic area
When cases occur at above normal rates
the number one cause of death worthwide
most infectious agents have what type of relationship?
commensal - they benefit but we are not harmed
ifectious agents that can cause disease
Infectious agents are usually microscopic and are typically called
smallest and largest microbe
smallest: protein molecule
largest: intestinal worms
T/F: many agents are living things
False: a living thing is something that has its own metabolism and reproduces
what's an example of a living infectious agent? non-living?
mere molecules, a corrupted form of normal brain protein
packets of nucleic acid encased in a protein coat (capsid)
how do viruses produce their RNA and DNA?
invade the interior or a cell and hijack the cell's metabolism and reproductive machinery
what do viruses not have? why is this significant to antibiotics?
don't have cell wall or metabolism
this is sig bc antibiotics' effect relies on disrupting bacterioal cell membrane or metabolism (so not effective on viruses)
can viruses exist outside of a cell?
yes but can't multiply
can viruses transform infected cells into tumor cells?
yes (HPV causes cancer of cervix)
the intestine alone contains about ( ) species of bacteria, most of which are ( )
can bacteria live outside cell?
yes, they can live and reproduce or in any place given the right nutrients
how are bacteria vulnerable to antibiotics?
they have a cell membrane and require energy to live
what is an example of bacteria that is an exception to the rules?
do bacteria have DNA and nucleus?
have DNA but no nucleus
how are bacteria classified?
shape, need for oxygen, and color after a standard stain
crystal-violet (deep purple)
bacteria: lost color after staining
bacterioa: elongated forms
two distinctive forms of fungi
molds and yeast
fungi: long, branching, multicellular filaments (hyphae)
fungi: mulicellular clusters of budding round forms (spores)
fungi: in cool temperatures, usually grow as ( ) but at body temp deep infections occur in ( )
fungi: infections of skin, hair, and nails are cause by
parasites: motile, single cell, nucleated organisms that are capable of reproducing within cells
parasites: responsible for much illness and death in developing countries
parasites: inseacts spread some protozoa such as ( )
parasites: protozoa can be directly observed in...
blood smears, stool, or tissue sections
parasites: infect about 1/3 of world pop
helminths (parasitic worms)
most serious helminth
schistosomiasis (go through snail first then human)
parasites: small insect-like creatures that attach to or live in skin
parasites: may cause local skin irritation from bites, but they also may transmit pathogens
3 ways organisms cause damage after infection
2) release of toxins
3) provocation of an immune response
the degree of harmfulness of a microbe
most microbes (including viruses) exhibit a preference for a particular type of cell
toxin: from bacterial cell membranes as they die
toxin: prouced and excreted from bacteria
most endotoxins come from what types of bacteria?
viruses generally incite what?
some viruses (like herpes) causes ( )and others (like human papillomavirus) causes ( )
pus-forming reaction (pyogenic) is usually produced by gram-positive cocci such as ( ) or gram-negative bacilli such as ( )
-staphylococcus or stepococcus
-E. col or H. influenza
if infection acquired outside of a hospital it is a ( ) infection, it it's acquired in a hospital it's a ( ) infection
mode of transmission from reservoir to new host: sexual intercourse, syphilis, herpes
-most organisms penetrate through breaks in skin or sexual mucosa
mode of transmission from reservoir to new host: hep A, parasites
mode of transmission from reservoir to new host: fomites (inanimate objects)- doorknob, clostridium
mode of transmission from reservoir to new host: sneezing, rhinovirus
mode of transmission from reservoir to new host: mosquitos, Zika virus
when blood is the main infected tissue, the condition is called ( )
septicemia or sepsis
T/F: gram positive organisms are purple while gram negative are red-pink
T/F: virulence is the ability to cause disease
T/F: host immunity always decreases virulence
False: host immunity does not always decrease virulence and the host response may actually induce additional inflammation and damage
T/F: the incubation time varies b/w diseas
what are the major categories of infectious agents?
Name the crucial differences b/w viruses and bacteria
viruses are obligate intracellular parasites. Bacteria can live outside of cells. Viruses are packers of protein w/o a cell wall. Bacteria are more complex with a cell wall
An organism called Bacillus cereus grows in reheated rice and can cause food poisoning very quickly within four hours. It is more likely that endotoxin or exotoxin causes this disease?
exotoxin, performed, similar to that os Staphyloccus aureus
granulomas are most likely caused by what two types of organisms?
fungi and mycobacterium (TB)
the time b/w invasion and appearance of signs or symptoms, during which the organism attempts to proliferate
may occur in which the patient suffers from mild, nonspecific symptoms
a time of maximum acute, typical clinicial signs and symptoms
time during which symptoms fade
time during which no symptoms are present but the patient may feel fatigued
what causes malaria?
what causes rocky mountain spotted fever? (wood ticks, dog ticks)
what causes lyme disease? (deer ticks)
what causes plague? (rodent fleas)
bacterium Yersinia pestis
agent: bacteria, response:
agent: viruses, response:
LYMPHOCYTES, monocytes, few neutrophils
agent: mycobacteria and fungi
GRANULOMAS, lymphocytes, monocytes
agent: parasitic worms, response:
agent: protozoa, response:
usual result of acute virus infection
an effective host immune response that eliminates the virus
usually infects upper respiratory tact, causing tonsillitis and often presents in combo with conjunctivitis
a mjor cause of lower respiratory tract infections during infancy and childhood
respiratory syncytial virus (RSV)
influenza type: less common and causes mild disease
influenza type: severe respiratory infection
the most common cause of severe diarrhea among infants and young children
virus infection type: rhinovirus, norovirus, measles, hep A, influenza
virus infection type: herpes, hep B and C, HIV, HPV
virus infection type: can stimulate the development of neoplasia (HPV, EBV, KSHV)
causes about 90% of nonbacterial outbreaks of epidemic gastroenteritis around the world
the most common cause of vaccine-preventable illness worldwide
virus infections in which the immune system does not eliminate the virus
chronic viral infection: virus persists in noninfectious form but can periodically reactivated to cause recurrent disease and new infections
latent virus infections
chronic viral infection: Herpes simplex virus (HSV) is usually associated with...
oral cold sores and genital herpes
a variety of herpesvirus that infects blood monocytes and related cells and causes a wide array of illnesses depending on host age and immune status
T/F: vaccination against viruses has decreased the incidence of many virus diseases
T/F: vaccination against viruses increases cancer risk
Fasle: it decreases it
what virus is responsible for cold sores? shinles? infection mononucleosis?
-HSV 1 and 2
what virus is most likely to cause gastroenteritis on a cruise ship? the common cold during school year? involve parotids and gonads?
why are influenza vaccines recommended anually?
because the virus mutates
gram-positive cocci that cause acute pyogenic infections
gram positive cocci: varities of S. aureus that are resistant to treatment with late antibiotics
methicillian-resistant styphylococcus aureus
gram positive cocci: S. pneumoniae, S. pyogenes
bacterial infections: very common aerobic pathogens that cause acute, intense, pyogenic infection
gram positive cocci
bacterial infections: cause illnesses closely identified with each species
gram positive bacilli
gram positive bacilli: diptheria is an acute pharyngeal or skin infection caused by ( )
gram positive bacillus: growns at fridge temp and causes food-borned infections through contaminated dairy products, raw veggies, and raw chicken and other meats
gram positive bacillus: large, toxin producing, encapsulated, aerobic or anaerobic...produces spores capable of lying dormant in soil for decades or longer
gram positive bacillus: grow in distinctive branched chains similar to fungal hyphae and are widely found in soil
gram positive bacillus: anaerobe that grow in animal feces and sol
gram positive bacillus: clostridium difficile causes ( )
4 types of clostridia:
1) C. difficile
2) C. perfringens
3) C. tetani
4) C. botulinum
the only important gram negative cocci
2 types of neisseria
N. gonorrhea and N. meningitidis
gram negative bacilli: E coli, salmonella, shigella, vibrio cholera, helicobacter pylori
gram negative bacilli: H. influenza, legionella, bordatella pertussis
gram negative bacilli: opportunistic or nosocomial infections
bacterial infections: transmitted by insect bites
rickettsiae and borrelia
bacterial infections: corkscrew-shaped
ex. of spirochetes
bacterial infections: often a mixture of organisms
myobacteria TB is the agent of ( ) while myobacteria leprae is the agent of ( )
TB incites distinctive chronic granulomatous inflammation, which features a central area of semi-solid criumbly, necrotic tissue called ( )
pathogenesis of TB: many infected but few are diseased
pathogenesis of TB: in about 5% of initial infections, the immune system cannot control spread and infection immediately progresses to active disease
primary progressive TB
pathogenesis of TB: arises from dormant primary TB bc the patient has developed a chronic, debilitating disease such as diabetes, chronic lung disease, or malignancy
skin test for infection
purified protein derivative (PPD) test-- aka Mantoux test
T/F: anaerobic bacteria are present in the mouth and are responsible for aspiration pneumonia
T/F: staphylociccus and step are gram postive bacteria that can infect a number of different organs
T/F: in testing for TB, a purified protein derivative test of less than 15 mm is always considered negative
False: in high risk or immunocompromised patients, it would be considered positive