Unusual Bacteria & Intro. to Pathogenesis Flashcards
name the aerobic and anaerobic members of the Actinomycetalesfamily
- aerobic:
-
Mycobacterium
- M. tuberculosis (TB)
- M. leprae (leprosy)
- M. marinum (wound infxns)
- Nocardia
-
Mycobacterium
- anaerobic:
- Actinomyces
explain why the cell wall in mycobacteria is different from other bacteria
- mycolic acids
- “waxy” outer coat
- results in slow growth (longer incubation times; chronic infxns)
- limited penetration of nutrients leads to slow growth
- more difficult to stain; Gram stain does not work reliably
- arabinogalactan
describe acid-fast staining (Ziehl-Neelsen method) and which bacteria it is used for (2)
describe bacterial species without a cell wall
Mycoplasma spp.
- smallest prokaryotes capable of independent growth
- adaptation: sterols in membrane
- 5 families: Mycoplasmatoceae most significant
- 2 key species:
- Mycoplasma
- Ureaplasma
describe bacteria that have unusual lifecycles (2)
Chlamydia and Rickettsia sp.
- cannot survive outside of living host cell
- cannot be cultured on laboratory media
- small enough to pass through usual bacteriological filters
- Gram stain isn’t normally used: tissue stains e.g. Giemsa
describe the biology of the unusual lifecycle bacteria
- obligately intracellular
- dependent on host for ATP and NAD
- can’t synthesize ATP or reoxidize NAD
- no detectable flavoproteins or cytochromes
- no peptidoglycan cell wall
- genus specific LPS
- dependent on host for ATP and NAD
- Chlamydia: complex and unusual life cycle with 2 developmental forms
- elementary bodies (EB): infectious form
- reticulate bodies (RB): replicative form
name the 2 developmental forms of Chlamydia
- elementary bodies (EB): infectious form
- reticulate body (RB): replicative form
describe the basic properties of algae (eukaryotes)
- unicellular (microscopic)
- diatoms, dinoflagellates
- multicellular (macroscopic)
- seaweeds
- mostly aquatic; important for primary productivity and as a direct food source
- cellulose walls
- photosynthetic
- contains chloroplast and chlorophyll
list the microbial factors vs the host immune resposne that contribute to the clinical signs and symptoms of an infxn
-
microbial factors:
- physical impact of growth in a specific location/tissue
- damage due to:
- enzymes
- toxins
- cellular components/products
- ability to sense and respond to environment
-
host immune response
- cytokines, interleukins, respiratory burst enzymes, etc.
describe the steps in the establishment of infection
describe an infection with gonorrhea
- acute infection
- factors that cause damage:
- microbial
- lipooligosaccharide
- antigenic variation
- inflammatory response
- microbial
- factors that cause damage:
describe true vs. opportunistic pathogens
define a true pathogen
- able to cause infxns in a healthy host, with intact defenses
- “virulent” due to production of:
- toxins
- adhesins
- enzymes
- capsules
- evasion of immune system: antigenic variation, etc.
who is at risk for opportunistic infxns?
- host with damaged or deficient defenses (acquired, infection, etc.)
-
situations that can predispose to an opportunistic infection tend to be:
- weak/malfunctioning immune system
- disruptions to normal flora
- breach of barriers (skin, mucosa)
- opportunistic pathogens are often:
- microbial flora of host (endogenous)
- environmental fungi
name the conditions that predispose to opportunistic infections
- HIV/AIDS
- diabetes mellitus
- renal failure
- hematological malignancy
- infectious diseases (e.g. tuberculosis)
- autoimmune disorders
- chronic glomerular disease
- immunosuppressive therapy
describe Treponema pallidum and syphillis (chronic infxn)
describe Mycobacterium tuberculosis and TB (latent infxn)
