Antimicrobial Resistance Flashcards

Question

Resistance Mechanisms

Answer 1

resistance genes can be: 1) on the bacterial chromosome (intrinsic) OR 2) on a motile gene element called a plasmid (circular strand of DNA) MOST IMPORTANT**** often have costs associated with them (fitness or metabolic) always on OR inducible lack of selective pressure will result in the loss of a particular resistance mechanism

Answer 2

1) Efflux pump -drug gets in, bug pumps it out 2) Reduced permeability -bacteria cell wall change size of porins to not allow drug to enter -normally allow proteins to move in and out 3) Enzymatic inactivation -bacteria produces protein/enzyme eats up the antibiotic -“ases” - beta-lactamase (penicillin) 4) Altered binding site -antibiotic binds to something, can no longer bind to to what it needs to e.g. vancomycin binds to: d-ALA, d-ALA, d-ALA etc. -MRSA - vancomycin can no longer bind

Answer 3

1) Conjugation -most important and common** -bacteria build bridge between each other - can transfer material between each other -gene transfer and recombination in bacteria that requires direct cell to cell contact 2) Transformation -naked DNA is taken up by a bacterial cell and incorporated into the recipients genome -free DNA fragments or a DNA plasmid -cell must be a competent cell to take up DNA -bacteria are floating around and see DNA, take capsule from the DNA -acquires capsules from the environment -e.g. strep pneumo 3) Transduction -bacteria have viruses can attack them called bacteriophages -bacteriophages carry this - e.g. resistant mutation, bacteria will become resistant to antibiotic -gives the bacteria resistance -e.g. Salmonella

Answer 4

ones we worry about can share quite effectively circular double stranded DNA that can exist and replicate independent of chromosome not required for cell’s growth may integrate with the chromosome

Answer 5

selective pressure e.g. use to use ciprofloxacin in the early 2000s for E. coli, top cause of UTIs -stop using cipro for UTIs in 2010s -now using it again -can cycle

Answer 6

over use of antibiotics are a major reason (e.g - using an antibiotic for a viral infection) not completing a prescription - allows partially treated organisms to develop or become resistant use of antibiotics in our animal feeds using a left over prescription from someone else or another time

Answer 7

Methicillin Resistant Staphylococcus aureus (MRSA) Vancomycin Resistant Enterococcus (VRE) Clostridium difficile (CDI)

Answer 8

ESBL’s - Extended spectrum Beta-lactamase producers -does not respond to cephalosporins -respond to carbapenems CRE/CPE - Carbapenem resistant Organisms

Answer 9

most virulent - causes the most disease common colonizer of skin, the nose and the perineum pne of the most common causes of soft skin infections, bacteremia, endocarditis, pneumonia and wound infections (soft tissue=bad) Types: -MRSA - resistant (increased morbidity, mortality) -MSSA - sensitive

Answer 10

S.aureus cell wall is made up of penicillin binding proteins (PBP) that are targets for beta-lactam drugs MRSA -changes affinity of binding site -reduces ability of beta-lactams to bind to MRSA

Answer 11

screen ANYONE that has had any contact with a health care facility in the last year due to the increased risk of invasive infections and the limited therapeutic options swab nose and butt if colonized --> contact precautions prevent: HAND WASHING

Answer 12

2 types relatively harmless, normal residents of the GI tract that occasionally cause infections, but typically in patients that are already very sick vancomycin sensitive or resistant screening: butt swab if colonized --> contact precautions significant amount of intrinsic resistance so not very many therapeutic options for treatment modifies d-ALA-d-ALA so vancomycin can't bind prevent: ENVIRONMENTAL CLEANING

Answer 13

can be colonized without diarrhea treat 3 diarrheal episodes in 24 hour without explanation children under 2 can't get not part of normal flora normal flora does not allow C. diff to colonize GI tract disturbance to normal flora allows it to grow produces spores - very environmentally stable toxin mediated, symptoms, RFs prevent: ENVIRONMENTAL CLEANING

Answer 14

risk factor is antibiotic use but also use antibiotics to treat vancomycin and metronidazole high chance of re-currence Fecal Microbial Therapy

Answer 15

produce beta-lactamase enzyme that break up the beta-lactam ring which inactivates antibiotics (penicillins, up to 3rd gen. cephalosporins) E.coli and/or K. pneumoniae can use carbapenems risk factors: -antibiotic use -travel -hosp. -carriage of ESBL in GI

Answer 16

any gram NEGATIVE that lives in your GI tract that is resistant to a Carbapenem last line drug - serious, resistance infections super bug RF: -travel for medical tourism (India, Israel, Greece, US) -exposure to some with a CRE -use of antibiotics over time