antibacterials Flashcards
(84 cards)
invaders
- bacteria (protozoa- no nuclei)
- fungi (eukaryote)
- protozoa (eukaryote)
- helminth (eukaryote)
- viruses
chemotherapy
drugs selectively toxic to invader
- minimal effect on host
bacterial infection example
necrotizing fasciitis (flesh eating disease)
necrotizing fasciitis
- break in skin, nutrients, warm and moist environment for bacteria
- bacteria release chemicals that kill human cells
- antibiotic treatment
prokaryotic cells
- DNA not in nucleus
- adaptable
- wide range of environments like temps and levels of oxygen(diff types)
- pathogenic and non-pathogenic
what is infection
invasion and multiplication of organisms that lead to untoward consequences
- from foreign bacteria or normal flora
colonization
- normal flora that live on/in our body
- non-pathogenic
- if circumstances change in person, colonization can become infection
bacteria shapes
- cocci (circle)
- bacilli (rods)
- strepto (chains)
- staphylo (clumps)
bacterial cell wall
- outside plasma membrane
- structural support (internal osmotic pressure)
- protection
- gram positive or gram negative (key difference for drug therapy)
gram positive cell wall
- thick peptidoglycan layer (50%)
- gram stain trapped in wall, gram stains purple
gram negative cell wall
- thin peptidoglycan layer (5%)
- has outer membrane
- less gram stain trapped
- harder to treat bc outer membrane is a barrier to antibiotics
gram positive bacteria example
staphylococcus aureus
gram negative bacteria example
escheria coli
narrow spectrum antibacterials
selective against one class of bacteria
- ex. only gram positive
broad spectrum antibacterials
effective against both classes of bacteria (g-ve and g+ve)
- can affect healthy bacteria you do not want to get rid of
bactericidal
directly lethal to bacteria (kill)
bacteriostatic
slow bacterial growth
- host immune system helps body control/eliminate bacteria
superinfection (suprainfection)
- new microbes take over when antibacterials kill normal flora
- new microbes are resistant to drug action and difficult to treat
opportunistic infections
- infections that would normally not harm person
- existing colonization become infections
- antibiotic took out normal flora so new infections have no competition
- common in immunocompromised
antibacterial drug resistance
bacteria less susceptible to drug action
- bacteria pumps drugs out
- enzymes break down/change drug
what causes drug resistance (mutation)
- choosing wrong antibiotic
- dose too low
- dose not taken long enough
- improper use (treat virus)
- prophylactic use (animal feed)
host factors affecting drug choice
age, allergies, organ health, pregnancy, site of infection, general health
antibacterials mechanism of action
- disruption of metabolic reactions
- interference with cell wall synthesis
- interference with protein synthesis
- interference with DNA replication/transcription mechanisms
antimetabolite example
sulfonamides
- sulfamethoxazole