Survey of Pathogenic Microorganisms Flashcards
What are viruses?
infectious particles with DNA or RNA surrounded with a capsid (protein coat)
What is the purpose of the lipid membrane around virus capisd?
to help with host cell recognition and spikes to aid in attachement ot cells
What cells do cold viruses target?
cells of the respiratory epithelium
Where does herpes viruses reproduce?
in nervous tissue
how do signs and symptoms manifest in viruses?
it depends on the way these viruses reproduce in cells or from the way the immune system responds to viral infection
what is a latent infection?
virus inserts itself into cell DNA and doesnt repicate (= no s/s) until a trigger such as s stress, infection with another pathogen, or a weakened immune defense activates the virus
Whre do HIV cells reproduce?
in t cells
What is bacteria?
microscopic, single-celled organism, w/o organelles
Shapes of bacteria?
cocci - round
bacilli - rodshaped
spirilla - spiral
spirochetes - corkscrew
vibrios - comma
What gives bacteria it’s key shape?
it’s cell walls
How does penicillin stop bacteria?
inteferes w/ correct cell wall construction = lyse
What is the gram stain?
thick walls = purple, thin walls = pink, in certain cells = easy identification
Examples of intracellular parasites + what r they?
chylamydias - STI
Rickettsias - transmitted by ticks = diseases like typhus and Rocky Mountain spotted fever
What are endospores?
some species of bacteria have them to stop them from drying out, lack of nutrients and extreme weather such as heat
in favorable conditions this endospore can germinate and produce bacteria
Bacteria that produce endospores include the causes
of ____________________________________
tetanus, botulism, and anthrax
Wjat is an endotoxin?
the potent toxin released by some bacteria into tissue when gram-neg bacteria die (can = life-threatening shock)
What is caused by toxin produced by bacterium Clostridium tetani?
tetanus- it interferes w/ muscles ability to relaxe = frozen, rigid, muscles
What are protozoa?
single-celled eukaryotic microorganisms that r larger than bacteria, found almost in every habitat, do not cause disease but can invade and destroy certain tissues
what are the types of protozoa
amoeboids - uses pseudopodia to move, ex is entamoeba histolytica (amoebic dysentery)
Flagellates - uses flagella to move, ex is trichomonas vaginalis which causes trichomoiasis (STI) and Giardia, causes giardiasis which is an intesitnal infection
ciliates - uses cilia to move
Sporozoans - not mobile, plasmodium causes malaria
Every year, more than ________ people worldwide become severely ill with malaria and more than ____ people die as a result.
500 million
1 million
Malaria kills mostly _______________________, largely in _______.
infants, young children,and pregnant women
in Africa
Plasmodium is transmitted via____________________
the bites of infected mosquitoes.
What are fungi?
single-celled or multicelled organisms
has cell walls that contain a polysaccharide called chitin absorbs nutrients w/ mycelia
has allergens which r the reproductive structures bearing spores
What are fungi?
single-celled or multicelled organisms
has cell walls that contain a polysaccharide called chitin absorbs nutrients w/ mycelia
has allergens which r the reproductive structures bearing spores
What are fungal infectiosn known as?
mycoses - its unsually opportunistic
How do fungi cause disease?
by producing toxins which interfere w/ the anatomy of physiology of organ = inflammation or allergy
what is candiasis
infection of skin or mucous membrane caused by Candida albicans
what does Pneumocystis jirovecii cause/
pneumonia- is a diagnostic indicator disease for AIDS
What are helminths?
parasitic worms thar r complex, multicellular, motile, capable of reproducing a lot of offsprings
infections with helminths r known as ________________
infestations
What is Ascaris?
infections 1.4 billion ppl, mostly in tropical or subtropical regions through the consumption of soil (or uncooked food contaminated by the soil) contaminated by human feces
when consumed the eggs hatch into larvae in the small intestine, mature into adults, and female produce more eggs
how to diagnose ascaris?
stool samples, treated with drugs
What are hookworms?
Causes anemia and protein malnutrition,
afflicting an estimated 740 million people in the developing
nations of the tropics
The largest numbers of cases occur in sub-Saharan Africa,
Latin America, Southeast Asia, and China.
Larvae of the hookworm penetrate the skin of the foot, hand, arm, or leg. The larvae travel to the small intestine and mature into adult worms.
How is hookworm diagnosed, treated, and prevented?
Stool samples are used for diagnosis, and drugs are available for treatment.
Prevention includes not walking barefoot, using toilet facilities, and not using human excrement or raw sewage as fertilizer in agriculture
Enterobius vermicularis, the pinworm, infects
an estimated __________ people worldwide and is
the most common worm infection in the United
States
200 million
How does pinworm infect ppl.
female pinworm deposits egg into skin around anus, secretes substance so host scratches area and transfers some of the eggs to the fingers
how long can pinworm eggs survive outside the body?
2-3 weeks
how is pinworm diagnosed?
using the graham sticky-tape method why placed a piece of transparent tape on the skin around the anus to pick up eggs
What is a prion?
short for proteinaceous infectious particle, is an infectious agent composed only of protein
causes spongiform encephalopathies (brain is riddled with holes)
what is a well-known prion disease?
mad cow disease
what do all known prion diseases do?
affect the structure of the brain or other neural tissue by
inducing abnormal folding of normal cellular proteins in the brain, leading to brain damage.
(progresses rapidly, is currently untreatable and fatal)
what are some examples of human prion disease + what is the most common?
Creutzfeldt-Jakob disease (CJD), familial Creutzfeldt-Jakob disease (fCJD), and kuru
CJD is the most common (occurs in about one out of every 1 million people)
How to treat bacterial infections?
using antibiotics
How to antibodies such as penicillin work
by attach to the cell wall (esp useful for controlling gram-positive bacteria)
what are some other ways antibiotics target bacterial cells?
causing lysis of bacterial cell membrane, targetting synthesis machinery of the cell, interfering with bacterial metabolism or w/ DNA or RNA synthesis
What is antibiotic resistance?
when bacteria adapt to antibiotics = antibiotics r ineffective
examples of antibiotic-resistant bacteria?
MRSA (methicillin-resistant Staphylococcus aureus)
&
VRE (vancomycin-resistant enterococci).
Group A streptococci cause only ___% of pharyngitis cases (strep throat)
15
How has the CDC asked physicans to make sure sore throat is rlly strep throat?
take throat swab and perform rapid strep antigen test to confirm
Why aren’t viruses susceptible antibiotics?
does not have the cell walls and cell membranes of bacteria, nor do they have metabolic or protein synthesis machinery
How do some antivrial drugs stop viruses?
some act as nucleic acid analogues that infiltrates DNA / RNA sequences and make them not act right
other viral drugs interfere w/ assembly of new virus particles inside cells
itnerfere with the attachment of viruses to host cells
How do antifungal drugs work?
used to target fungal walls and membranes but can affect human cells as well (topical has less effects but systemic as risk of serious side effects)
how are protozoa’s treated?
w/ drugs that itnerfere with protien synthesis and metabolism (can use some antibotics)
what drugs are helminths susceptible to?
drugs that paralyze their muscles or interfere with their metabolism
What is rocky mountain spotted fever/ tick bite?
- spotted fever, tickborne disease, severe systemic infections
- most commonly reported rickettsial disease in US
- pt may recall being bitten by tick, ticks may be inwarare of ticks present bc they r flat and small and hidden in area covered by hair, fever, severe headache, vomiting, malaise, myalgia, maculopapular rash, small hemorrhages, vasculitis, systemic manifestations in the heart, lujngs, kidnets, nervous systems, skin begins to peel
etiolofy of tick bite?
- rickettsia rickettsii
- transmitted by wood ticks and is carried in feces of infected ticks
- introduced into bloodstream of a person during a prolonged tick bite (during 4 to 6 hrs)
diagnose and treat tick bite?
diagnose - history of tick bite or recent outdoor activity in tick-infested area, systemic sympotms: characterisitc rash, positive complement fixation reaction which measues the antigen-antibody reaction, clotting component in blood may e noted, blood cluture
treat - antiotbitic therapy and anlgesics
Ehat is malaria?
- severe generalized infection caused by bite of an Anopheles mosquito that is infected by a Plasmodium type of protozoa
- s/s r acute, sometimes chroinc, serious infectious illness, characteried by classic cycles of chills, fever, sweats, headache, nausea, fatigue, myalgia, enlarged speen, enlarged liver, anemia
etiology of malaria?
- 4 species of protozoan Plasmodium (transmitted from inected human to human by bites of mosquito vectors or, less commonly, blod transfusions or IV drug use
- protozoans feed on hemoglobin and reproduce within RBCs
- endemic t tropical and subtropical areas such as South and Cental America, Asia, Africa
diagnose and treat malaria?
diagnose - lab testing reveals decreased hemoglobin level, decreased platelet count, prolonged prothrombin time (PT), positive serum antibodiy test, identify Plasmodium organism in blood smear
treat - chloroquine, antimalarial drug, antipyretics, infusions of packed RBCs
