week 4: Ch. 6- Infection Flashcards
Pathogens:
Disease-causing microbes
Bacteria
Classified as:
Function:
Divide by:
Structure:
Appearance:
◦ Classified as prokaryotes
◦ No nuclear membrane—no nucleus
◦ Function metabolically & reproduce
◦ Divide by binary fission
◦ Complex cell wall structure
◦ Do not require living tissues to survive
◦ Vary in size and shape
Bacilli
Rod-shaped organisms
Spirochetes
Include spiral forms and Vibrio spp.
Cocci
Spherical forms
◦ Diplococci
◦ Streptococci
◦ Staphylococci
Two types of bacteria that differ in chemical composition:
◦ Gram-positive
◦ Gram-negative
External capsule or slime layer
◦ Found in some bacteria
◦ Outside the cell wall
◦ Offers additional protection
Flagellae
◦ One or more attached to cell wall
◦ Provide motility for some species
Pili or fimbriae
◦ Tiny hairlike structures—found in some bacteria
◦ Assist in attachment to tissue
◦ Transfer of DNA to another bacterium
Cell membrane
◦ Inside the bacterial cell wall
◦ Selectively permeable
Cytoplasm contains:
◦ Chromosome- One long strand of DNA
◦ Ribosomes and RNA
◦ Plasmids- DNA fragments; nonchromosomal; exchange DNA during conjugation
Exotoxins are usually produced by:
gram-positive bacteria
Endotoxins
Present in:
Released:
Can cause:
◦ Present in the cell wall of gram-negative bacteria
◦ Released on death of bacterium
◦ Vasoactive compounds that can cause septic shock
Spores
Formed by:
__________ form of bacterium
Can survive:
Highly resistant to:
◦ Formed by several species
◦ Dormant-latent form of bacterium
◦ Can survive long periods of time in spore state
◦ Highly resistant to heat and disinfectants
Viruses are small:
obligate intercellular parasites
Viruses structure
◦ Protein coat or capsid
-protein coat comes in various shapes and sizes
◦ Can change (mutate) quickly
◦ Nucleic acid - DNA or RNA
◦ Classification dependent on nucleic acid present
◦ Some RNA-containing viruses contain reverse transcriptase enzyme to convert RNA to DNA.
Active Viral Infection steps
◦ Virus attaches to ___________
◦ Viral ___________ material enters cell.
◦ Viral _______________ takes control of cell.
◦ Uses host’s cell to synthesize ____________________________________________
◦ New viruses are assembled in cytoplasm of cell.
◦ Viruses released by ____________________________ from host cell membrane
◦ Virus attaches to host cell.
◦ Viral genetic material enters cell.
◦ Viral DNA or RNA takes control of cell.
◦ Uses host’s cell to synthesize viral proteins & nucleic acids
◦ New viruses are assembled in cytoplasm of cell.
◦ Viruses released by lysis of host cell or by budding from host cell membrane
Latent Viral Infection steps
◦ Virus enters cell as with active infection.
◦ Viral _________ are produced and Inserted into [may stimulate an immune response and destruction of host cell]
◦ Virus may ____________________________ if immune system is depressed (e.g., herpesviruses)
◦ Virus enters cell as with active infection.
◦ Viral proteins are produced and Inserted into [may stimulate an immune response and destruction of host cell]
◦ Virus may reproduce actively if immune system is depressed (e.g., herpesviruses)
Describe characteristics of Chlamydia, Rickettsiae,
Mycoplasmas
◦ Obligate intercellular parasites.
◦ Do not grow on artificial media
◦ Some similarities with both bacteria and viruses
◦ Lack some basic components
◦ Classified as bacteria
◦ Replicate by binary fission within host cell
Chlamydia
~cause of? results in?
◦ Common cause of sexually transmitted disease
◦ Can result in infertility
Rickettsiae
~Gram? Transmitted by?
◦ Gram-negative
◦ Transmitted by insect vectors (lice, ticks)
Mycoplasmas
~Lack? Causes?
◦ Lack cell wall
◦ Cause of atypical type pneumonia
___________ (fungus) can cause neurologic disease and can be transmitted to embryo or fetus if mother is infected
Histoplasma
Fungi
◦ ________________ organisms (contain nucleus)
◦ Found throughout environment - On animals, plants, humans, food
◦ Fungal or mycotic infection
◦ From single-celled_________ or multicellular molds
◦ Only a few are _________________.
◦ Cause primary infection on skin or mucous membranes but may spread systemically particularly in immunosuppressed individual
◦ Eukaryotic organisms (contain nucleus)
◦ Found throughout environment - On animals, plants, humans, food
◦ Fungal or mycotic infection
◦ From single-celled yeast or multicellular molds
◦ Only a few are pathogenic.
◦ Cause primary infection on skin or mucous membranes but may spread systemically particularly in immunosuppressed individual
_______________ (fungus) is AKA athlete’s foot
Tinea pedis
Candida (fungus):
usually harmless, but opportunistic
◦ Causative agent of :
thrush and vaginitis
Protozoa
◦ Eukaryotic forms
◦ Unicellular, lack cell wall
◦ Many live independently, others are obligate parasites
◦ Pathogens are usually parasites.
◦ Examples of protozoal diseases:
-Trichomoniasis
-Malaria
-Amebic dysentery
Helminths (flatworms or roundworms)
◦ Are not microorganisms
◦ Parasites
◦ May be small or up to 1 m in length
◦ Life cycle with 3+ stages- Ovum, larva, adult
◦ Enter body through skin or by ingestion
◦ Infections more commonly found in young childs
◦ Infection can be life-threatening in an immunosuppressed client.
