Medical Microbiology

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VIRUSES

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Enveloped

Naked

Hyphae-multicellular filaments, divided by septa

Both -/+ have: -Glycocalyx (sugarshell) -Capsule-compact layer *protection from phagocytosis* -Slime Layer-runny, unorganized *contributes to biofilm*

Microbes

NON-LIVING

Acellular

Prions

-one single protein -NO nucleic acid -Transmissible Spongiform Encephalopathies (TSE) ----slow fatal neurodegenerative disease ***brain tissues develop holes scrapie --> goats mad cow and kuru --> people

Viroids

-small single strand RNA -NO protein coat -cause disease in plants

Viruses

"obligate intracellular parasites" -need host cell for protein synthesis machinery -very small -Structure:

Infections

Persistent

years of lifetime

Latent

periods of latency with potential for reactivation to productive infection

Herpes (cold sores) Varicella zoster (chicken pox --shingles)

Chronic

virons constant release in low levels = productive

Hep. B HIV

Acute:

rapid onset short duration

Genome Replication:

Retroviruses --> reverse transcriptase to transcribe

RNA --> RNA replicase

RNA/Retro rapidly undergo antigenic drift

mechanism for variation in viruses (accumulation of mutations)

DNA --> DNA polymerase

DNA will NOT make mistakes

LIVING

microorganisms

Complex cells

Eukaryotes

Helminths

Worms

3) Insect Bites transmit tiny thread like worms

River Blindness --black fly

Elephantiasis --mosquito

2) Burrow through skin (bare feet, poor sanitation)

Schistosomiasis

1) Ingestion

feces-->pinworm, asariasis raw meat-->tapeworm

Protozoa

unicellular, heterotrophs -lack cell wall -motile

Toxoplasmosis --cysts ingested

pregnant women kitty litter

REMEMBER: protozoan cysts can withstand stomach acid **essential for fecal-oral route

Giardiasis --fecal-oral-cyst form

beaver fever

Malaria --Mosquito vector

Fungi

Cause Human Illness

3) Mycoses -fungal infections grow on/in body

Lung infection --**worse on immunocompromised

Candida (mucous membrane) --vulvovaginal, oral thrush

Dermatophyte --Ringworm,Jock itch

2) Allergy/Asthma -hypersensitivity

1) Intoxication -toxins poisonous

Heterotrophs -cell wall CHITIN -Ergosterol in cell membrane -target for antibiotics

Morphological Forms:

Mushrooms -multicellular -reproductive structures:

**obtain nutrients by secreting digestive enzymes

Moulds -multicellular

Yeasts -unicellular

Algae

Autotrophs -cell wall made of cellulose -toxins--> paralytic shellfish poisoning

Simple cells

Prokaryotes

Bacteria

Chapter 20 Part 1

Narrow Spectrum

target a specific group **must know exact target

Broad Spectrum

effective against >1 group of bacteria **kills microflora

Selective Toxicity

kills microbes --> low toxicity to humans

Chapter 4 Growth

Factors Affecting Growth

Expectations

Endospores --> bacillus and clostridium

Myobacteria --> waxy, lipid cell wall

Mycoplasma --> lack cell wall

Nutrients

Fastidious

cannot make things from scratch

Versatile

can make things from scratch

Salt

Extreme Halophiles

require high salt

Halophiles

require salt

Halotolerant

small amount of salt

pH Requirements

Alkaliphiles

pH >8 (high pH)

Acidophiles

pH <5 (low pH)

Neutrophiles

grow best pH~7

Oxygen Requirements

Microaerophile

needs small amounts of oxygen

contain enzyme to detoxify (only have a few enzymes to break down oxygen)

Aerotolerant Anaerobe

indifferent to oxygen -doesnt care either way

contain enzyme to detoxify

Obligate Anaerobe

must have NO oxygen (poisoned by oxygen)

does NOT contain enzyme to detoxify -endospores survive

Facultative Anaerobe

"make do" without oxygen but grow better with

contain enzyme to detoxify

Obligate Aerobe

MUST have oxygen

Contain enzymes to detoxify

Temperature

psychro/meso/thermo

Calculating Growth

#=initial # * 2^(#of doublings)

Generation Time

amount of time it takes to double

Binary Fisson

splitting into 2

Chapter 3 Structure

Appendages

Sex Pilus

Conjugation (transfer of plasmid DNA)

Fimbriae

attachment to surfaces

Flagellum

Mobility and enables chemotaxis

Gram-Negative

-thin PTG wall -outer membrane -LPS-endotoxins -porins

Gram-Positive

-thick PTG wall (many layers)

Cell Wall

-PTG -specific to bacteria -protection against lysis -essential for survival

Chromosomal DNA

-basic genome -all contain this DNA

Ribosomes (70s)

-cannot survive without protein synthesis (70s)

Plasmid DNA

-Contains genes resistant to antibiotics

Cell Membrane

-regulates the entry and exit of substances -*transport and receptor proteins*

Archaea