Infectious Agents Flashcards
virus membrane/ cell wall
protein capsid
some have host cell envelope
bacteria membrane/ cell wall
G + thick peptidoglycan
Sterols: mycolic acids in crynebacteria, mycobacteria and nocardia; cholesterol in terponemes & borrelia
Fungi membrane/ cell wall
ergesterol
chitin
What is obligate intracellular?
all viruses
bacteria: clamydia, rickettsia, coxiella, erlichiae, anaplasma and some mycobacteria (M. leprae)
What is the domain of fungi and parasites?
eukaryotes
Prions
PrP sc converts to PrP c proteins
Version: Kuru, Creutzfeld-Jakob disease, Bovine spongioform encephalopathy (can end up as a variant of CJD), Scrapie (goats scraping themselves)
Normal flora found where?
skin, nasopharynx, oral cavity, vagina, colon
Routes of microbial infection
skin, gi tract, respiratory tract, urogenital tract
B cell defects –>
bacteria (specially encapsulated), giardia and some viruses
deficiency of C1, 2 or 4
Encapsulated bacteria (S. penumo)
deficiency of C3
encapsulated bacteria
deficiency of C5,6,7,8 or 9
Neisseria (gonococcus and meningococcus)
deficiency of neutrophil function
S. aureus, gram neg. bacteria, fungi
deficiency of toll-like receptor signaling
susceptible to S. pneumo, viruses
T cell defects
bacteria, viruses, fungi, parasites
phagocytosis defect or splenectomy / sickle cell anemia susceptible to?
susceptible to encapsulated bacteria
splenectomy patients need vaccinated against
encapsulated bacteria!
pneumococcal, etc.
example of suppurative (purulent) infection
staphylococcal pneumonia
Examples of mononuclear and granulomatous inflammation
syphilis (mononuclear cell infiltrates)
tuberculosis (formation of granulomata)
Example of cytopathic-cytoproliferative reaction
herpes virus
Example of tissue necrosis pathogen
clostridium perfringens
example of chronic inflammation/ scarring
chronic hepatitis (cirrhosis)
example of something that elicits no immune reaction
mucormycosis in bone marrow transplant patients
Rapid Testing in Microbiology- direct microscopy
Gram for bacteria and fungi
H&E and Papanicolaou stains for viral changes, fungi and bacteria
Auromine-rhodamine immunofluorescence for mycobacteria and cryptosporidium
Calcofluor white stain for fungi
Acid fast stain for mycobacteria
Silver stains for fungi, spirochetes, pneumocystis
PAS stain for fungi
Mucicarmine stain or India ink for cryptococcus capsule
Giemsa stain for parasites and campylobacter
rapid testing in microbiology: antigen/ antibody detection
Enzyme immunoassays (EIAs) – giardia, cryptosporidium, Direct fluorescent antibody and latex agglutination – bordetella, legionella, pneumocystis, treponema, group A or B streptococci
rapid testing– molecular detection
Nucleic acid probes and nucleic acid amplification – chlamydia, gonococcus, tuberculosis, CNS infections (herpes, Epstein-Barr, varizella zoster, cytomegalovirus, enterovirus, parechovirus)
rapid testing- serology
Bacteria (helicobacter, bordetella, borrelia, pneumococcus, treponema), viruses (Epstein-Barr, hepatitis viruses, CMV, HIV, etc.), fungi (blastomyces, histoplasma, coccidioides, etc), parasites (toxoplasma, girardia, babesia, etc.)
minimum inhibitory concentration
The lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation
Key words: ** after overnight **
Catalase (+)
staphylococci
S. aureus, e.g.
Catalase (-)
streptococcus (and enterococcus)
S. epidermides, e.g.
Hemolysis
used for streptococci Blood agar plate alpha = partial (green) beta = total gamma = no hemolysis
Fermenter
Lac (+) E. Coli, Enterobacter and Klebsiella
Sabouraud dextrose
culture for fungi
