antibacterials Flashcards
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
sulfonamide characteristics
- broad spectrum
- bacteriostatic
-prevent synthesis of folic acid
sulfonamide (sulfamethoxazole) mechanism of action
inhibit enzymes so bacteria can’t make folic acid (DNA/RNA), cells can’t replicate
sulfonamide (sulfamethoxazole) indications
- UTI
- otitis media
- upper resp tract infections
- malaria
- chlamydia
what drug is sulfamethoxazole combined with? why?
trimethoprim
- makes more effective bc stops at 2 spots in folic acid pathway
contraindications
- allergies (to all sulfa drugs)
- pregnancy (birth defects, increase fetal bilirubin)
- breastfeeding
- infants < 2 mths
sulfonamide adverse effects
- skin allergies (hypersensitivity, steven-johnson syndrome, photosensitivity)
- bone marrow depression (agranulocytosis, thrombocytopenia, aplastic anemia)
- nausea and vomiting
steven-johnson syndrome
swelling and rash of mucosal membranes
sir alexander fleming findings
mold growing on growth plate made chemical that kept bacteria away (starting point of antibacterial drugs)
beta lactam antibacterial characterstics
- inhibit cell wall enzyme responsible for peptidoglycan synthesis (stop cell wall)
- bactericidal
- beta lactam ring is effective part of drug