Clinical ID Flashcards
1
Q
viruses
A
- 20-30 nm
- obligate intracellular
- dependent on host cell metabolism for replication
- classified by the nucleic acid content of their core and shape of their protein capsid or coat
- cause acute illnesses
- capable of lifelong latency and of long term reactivation or of giving rise to chronic disease
- ex. ebola, herpes
2
Q
chlamydiae
A
- 200-100 nm
- obligate intracellular
- Can cause GU infections, conjunctivitis, respiratory infections & STDs
- obligate intracellular pathogens that divide by binary fission, are susceptible to antibiotics, but lack certain cell structures
3
Q
rickettsiae
A
- 300-1200 nm
- obligate intracellular
- Transmitted by insect vectors (lice, ticks, mites) and can cause Rocky Mountain Spotted Fever, Q Fever, ehrlichiosis &scrub typhus
- obligate intracellular pathogens that divide by binary fission, are susceptible to antibiotics, but lack certain cell structures
4
Q
mycoplasmas
A
- 125-350nm
- Tiniest free-living organism known and can cause atypical pneumonia & nongonococcal urethritis
- obligate intracellular pathogens that divide by binary fission, are susceptible to antibiotics, but lack certain cell structures
5
Q
fungi imperfecti
A
2-200um
-Possess thick cell walls
-Growth patterns include budding yeast and slender tubes called hyphae
-Hyphae produce fruiting bodies called conidia
Infect superficial layers of skin (Tinea)
-Deep fungal infections can spread systemically (some species limited to geographic regions eg. Blastomyces, -Histoplasma, Coccidioides)
-Opportunistic fungi that normally colonize the body may cause disease in immunosuppressed patients such as lethal pneumonia & tissue necrosis
6
Q
protozoa
A
- 1-50 um
- Parasitic, single-celled organisms with motility, pliable plasma membranes and complex cytoplasmic organelles
- Can be transmitted:
- sexually (Trichomonas)
- via the fecal-oral route (Giardia)
- by blood – sucking insects (Leishmania)
- by contact with infected cats or eating cyst ridden, undercooked meat (Toxoplasma gondii)
7
Q
helminths
A
- 3mm-10m
- Parasitic worms that are highly differentiated multicellular organisms
- Complex life cycles
- Most are dependent on an intermediary host or vector for asexual reproduction
- Disease is often caused by host inflammatory responses (ex. Schistosomiasis) and in proportion to the number of infecting organisms
- 3 classes: roundworms, flatworms, and flukes
8
Q
prions
A
- composed of modified host proteins (prion protein)
- cause transmissible spongiform encephalopathies
- assoc with neurodegenerative diseases such as kuru, mad cow disease CJD
9
Q
bacteriophages, plasmids, and transposons
A
- mobile genetic elements that encode bacterial virulence factors = plasmids and transposons
- include adhesins, toxins or enzymes that confer antibiotic resistance
- they can infect bacteria and incorporat themselves into their genome
10
Q
bacteria
A
- prokaryotes that lack nuclei and ER
- capable of synthesizing own DNA, RNA and proteins but rely heavily on host for favorable growth conditions
- grow both extracellularly and intracellularly
11
Q
round worms
nematodes
A
- collagenous tegument and non-segmented structure (hookworms & Trichinella)
- larvae penetrate skin (often through bare feet), are carried to lungs, go through respiratory tract to mouth, are swallowed, and eventually reach the small intestine. Cycle takes about a week.
12
Q
flatworms (cestodes)
A
- gutless worms
- heads sprout a ribbon of flat segments (tapeworms)
13
Q
flukes (trematodes)
A
-primitive leaflike worms with syncytial integument (schistosomes
14
Q
ectoparasites
A
- Arthropods (lice, ticks, bedbugs, fleas)
- Attach and live on skin
- May be vectors for other pathogens such as deer ticks transmitting Lyme disease, babesia and ehrlichia while the dog ticks are harmless
15
Q
breeches to host barriers by commensal bacteria
A
- skin bacteria can cause infection after etering through cuts
- GI system- virulent organisms can penetrate the intact mucosal barriers and cause infection
16
Q
spread and dissemination of mibcrobes
A
- The major manifestations of infectious disease may arise at sites distant from those of entry (eg. Chickenpox and measles enter through airways but manifest as skin rash
- Bloodstream invasion is a common event for both non-virulent and virulent microbes.
- The placental-fetal route is an important mode of transmission.
17
Q
how microorganisms cause disease
A
- direct cell death
- endo/exotoxins
- secondary response through host immune response
18
Q
mechanisms of viral injury
A
- Viruses inhibit host cell DNA, RNA or protein
synthesis. - Viral proteins insert into host cell’s plasma
membrane. - Viruses replicate efficiently and lyse host cells.
- Viral proteins on the surface of the host cells are
recognized by immune systems and host
lymphocytes attack the viral infected cells. - Viruses damage cells involved in secondary
infections. - Viral killing of one cell type causes the death
of another. - Slow virus infection and latency.
- In addition to causing injury, viruses induce cell
proliferation and transformation which can lead
to neoplasms.
19
Q
bacterial virulence
A
Depends on ability of bacteria to adhere, invade, & deliver toxic moieties
