MICR 208 Test 1 | Verified with 100% Correct Answers

MICR 208 Test 1 | Verified with 100% Correct Answers Which antimicrobial is able to cross the blood brain barrier? a) Carpapanems b) Chloramphenicol c) Aminoglycosides d) Vancomycin e) Tetracycline Which of the below is not used to test for frank penicillin/ampicillin resistance in enterococci? a) KB b) Broth dilution (automated) c) Cefinase test for beta-lactamase activity d) All of the above are used Which antibiotic classes are broad spectrum? Also include their general mode of action (BTCFSTN) Beta-lactams : inhibit cell wall synthesis Tetracycline: inhibit protein synthesis by binding 30s subunit chloramphenicol: inhibit protein synthesis by binding 50s subunit Fluoroquinalones: inhibit DNA synthesis by interfereing with DNA gyrase Sulfonamids, trimethoprim (combo): inhibit folic acid synthesis Nitrofurantoin: inhibit DNA, RNA, protien synthesis What drugs are considered cell wall synthesis inhibitors? (2; main) include examples Beta lactams -Penicillins -Carbapenams - monobactam - Cephalasporin - inhibitor combos Glycopeptides -vancomycin What drugs are cell membrane inhibitors? (1 broad) Lipopeptides - daptomycin: GPCs - colistin: GNBs What drugs are 30s subunit protein synthesis inhibitors? Aminoglycosides Tetracyclines Antimicrobials a) Inhibits organisms b) Kills organism c) Substances produced by an organism naturally or by synthetic means d) obtained and purified from other microorganisms Antibiotics a) Inhibits organisms b) Kills organism c) Substances produced by an organism naturally or by synthetic means d) obtained and purified from other microorganisms Emperical treatment Broad spectrum and used before causative organism is known Targeted treatment Narrow spectrum and used after causative agent and its susceptibility is known Which of the below is not an ideal trait for antimicrobials? a) Selectively toxic to the organism b) Low propensity for development of resistance c) Strong against a variety of organisms d) Long half life and easy to administer Which of the below is not a way in which microbes have developed antibiotic resistance to beta-lactams a) Generation of beta-lactamases to destroy the drugs b) Increases in the amount of PBPs to counteract the drug c) Altering the PBP so that the beta lactams cannot bind d) Producing a separate target for the beta lactams to work on instead (decoy) Which of the below is not a toxicity associated with beta lactams? a) Allergies b) Neurotoxicity c) Auditory toxicity d) Nephrotoxicity What is the role of cefinase test? Tests for beta lactamase activity against cephalosporins Which of the below is false regarding inhibitors used in inhibitor combinations for beta lactams a) Share a similar structure to beta lactams to act as decoys b) Have antimicrobial activity c) Bind to B-lactamases to allow B-lactams to exert their function d) Includes clavulanate, sulbactam, tazobactam, avibactam What is the activity of each of the below generations of cephelasporins? 1st 2nd 3rd 1st: GPC 2nd: GPC, and GN 3rd: Very good for GN (stable to beta-lactamases) Which of the below cephalosporin generations is stable against GN beta-lactamases? a) 1st b) 3rd c) 2nd d) 4th Which two cephelasporins are effective against MRSA? Ceftaroline Ceftobiprole Which of the below beta lactams has the broadest spectrum of activity and is stable against many beta-lactamases? a) Penicillins b) Monobactams c) Cephelasporins d) Carbapenams e) Inhibitor combos Which of the below is a beta-lactam that only works against GNB? a) Carbapenams b) Monobactams c) Vancomycin d) Cephalosporins e) Chloremphenicol When must you collect a sample to monitor the trough of an antimicrobial? What about a peak? Trough: within 30 minutes of the next does Peak: Within 30 minutes of the most recent administration Which of the below can cause allergic reactions? a) Penicillins b) Daptomycin c) Tetracyclines d) SXT e) All but one (c) Which of the below is the last line of defence against MRSA, VRSA, VRE? a) Tetracyclines b) Chloremphenicol c) Colistin d) Daptomycin T/F Natural penicillins are effective against Gram positive organisms and are stable against beta lactamases False - not stable against beta lactamases Which of the below would be best to treat against penicillinase producing staphylococci? a) Piperacillin b) Oxacillin c) Amoxacillin d) Penicillin Which of the below would be best to treat Enterococci compared to penicillin or a B-lactamase negative H. influenzae infection? a) Piperacillin b) Oxacillin c) Amoxacillin d) Penicillin Which of the below has increased activity against Gram-negatives that produce B-lactamase? a) Piperacillin b) Oxacillin c) Amoxacillin d) Penicillin Which of the below is good for gram-positive infections but are destroyed by B-lactamases? a) Piperacillin b) Oxacillin c) Amoxacillin d) Penicillin T/F Antibiotics that inhibit protein synthesis are typically bacteriostatic True What enzyme in the folic acid synthesis pathway do sulfonamides block? What about trimethoprim? Sulfonamides: dihydropterate synthase Trimethoprim: dihydrofolate reductase Which of the below classes is used for mycobacterium tuberculosis? a) Beta lactams b) Lincosamides c) Aminoglycosides d) Tetracycline e) SXT Which of the below would be useful in treating Brucella infection? a) Beta lactams b) Lincosamides c) Aminoglycosides d) Tetracycline e) SXT Which of the below would be hazardous to give to children or pregnant women? a) Tetracycline b) Chloremphenicol c) Quinolones d) Nitrofurantoin e) Two of the above a and c Which of the below would be useful against an anaerobic GP organism? a) Aminoglycosides b) Lincosamides c) Quinolones d) Colistin Which of the below are typically given to patients with a penicillin allergy? a) Chloremphenicol b) Clindamycin c) Clarithromycin d) Cephalosporin *lincosamides Which of the below drugs used to treat UTI's does not diffuse through tissues? a) Ciprofloxacin b) Nitrofurantoin c) Nalidixic acid e) Two of the above Which of the below drugs used to treat UTI's concentrates in the kidney and bladder? a) Ciprofloxacin b) Nitrofurantoin c) Nalidixic acid e) Two of the above Which of the below causes upper GI issues and pulmonary fibrosis? a) Sulfonamides b) Trimethoprim c) Nitrofurantoin e) All of the above The drug is no longer effective for clinical use a) Microorganism mediated resistance b) Environmentally mediated resistance c) Clinical resistance d) Biologic resistance Reduced susceptibility of an organism to a particular antimicrobial agent a) Microorganism mediated resistance b) Environmentally mediated resistance c) Clinical resistance d) Biologic resistance Resistance directly resulting from physical or chemical characteristics such as pH, temperature, atmosphere a) Microorganism mediated resistance b) Environmentally mediated resistance c) Clinical resistance d) Biologic resistance Genetically encoded traits, instrinsc or acquired resistance a) Microorganism mediated resistance b) Environmentally mediated resistance c) Clinical resistance d) Biologic resistance Which of the below is not related to intrinsic resistance? a) Natural and often encoded in the chromosome of the organism b) Could be the thickness of the peptidoglycan layer c) Is predictable d) Can be transferable T/F Intrinsic resistance is unpredictable while extrinsic resistance is predictable False other way Plasmids are considered a) Acquired resistance b) Inherited resistance c) Intrinsic resistance d) Altered resistance Which of the below is false regarding acquired resistance? a) Unpredictable b) Can be acquired through mutations c) Can be acquired through plasmids or other transposable elements d) Encoded in the chromosome or the organism naturally e) All of the above are true T/F Consituitive acquired resistance is acquired through genetic mutations True Can a mueller hinton plate be used for AST when testing for Streptococcus spp? Must have 5% sheeps blood added How thick should the media be for an AST test? a) 2mm b) 10mm c) 4mm d) 6mm How close can two antibiotic disks be on the plate? a) 24mm apart edge to edge b) 24mm apart center to center c) 34mm apart edge to edge d) 34 mm apart center to center Which of the below is incorrect for incubation conditions for a Kirby-bauer disk test? a) 35C b) 18-24 hours c) Ambient air d) All of the above are true **16-18hours What is the minimum amount of colonies that must be touched when making your McFarland standard for AST? 3 Why must you complete the set up for the Disk method AST within 15 minutes? E. coli only take 20 minutes to replicate, therefore this could lead to false resistance when reporting results Why must you leave the plate face UP for 5-15 minutes after swabbing your lawn? Allows the bacteria to diffuse into the agar properly T/F The KB disk method can be applied to all pathogens with the right modifications False, designed for fast growing, non-fastidious organisms, can be modified for SOME Which of the below should you incubate for longer if performing a KB AST? a) Staphylococcus spp/ b) H. influenzae c) MRSA d) VRE e) Two of the above c and d, for 24 hours How would you use an older culture to perform a KB? a) You can select 4-5 colonies to make your suspension in saline b) You can select 4-5 colonies to make your suspension in broth c) You can select 4-5 colonies to make a suspension and then grow to the 0.5 McFarland prior to plating d) You cannot use older cultures for a KB, you must streak them out on a new plate and wait 18-24H to get new cultures Which organism can you disregard the haze growth around for an SXT test on MH? a) Klebsiella spp b) Providencia spp. c) Escherichia spp. d) Proteus spp. If your inocculum is too light on a KB plate, this may result in a false ____________ Susceptible T/F If a drug is deemed R during AST testing, it will not be effective in the patient in every case False - 60% of the time it works! Which of the below methods are typically used for screening antibiotic resistance such as oxacillin for MRSA a) Kirby-bauer b) Broth dilution c) Agar Dilution d) Etest What suspension is used for a an antibiotic agar dilution screen? a) 1 x 10^5 CFU/L b) 1 x 10 ^8 CFU/L c) 1 x 10^2 CFU/L d) 1 x 10^4 CFU/L Which of the below gives a qualitative results rather than quantitative? a) Kirby-bauer b) Broth dilution c) Agar Dilution d) Etest Which of the below is particularly useful for testing antibiotc resistant pathogens? a) Kirby-bauer b) Broth dilution c) Agar Dilution d) Etest What is the difference between MIC and MBC? MIC = minimum inhibitory concentration; the concentration needed to INHIBIT growth of a microorganism MBC = minimum bacteriocidal concentration; the concentration needed to KILL 99.9% of the microorganism You performed breakpoint testing on an organism with the following categories for a certain antibiotic S = /= 8ug/ml I = 16 ug/ml R = 32 ug/ml if the organism ONLY grew on the plate with 8ug/mL of the antibiotic, what does this mean? a) Sensitive b) Resistant c) Intermediate You performed breakpoint testing on an organism with the following categories for a certain antibiotic S = /= 8ug/ml I = 16 ug/ml R = 32 ug/ml if the organism grew on the plate with 8ug/mL, and 16ug/mL, but not 32ug/mL of the antibiotic, what does this mean? a) Sensitive b) Resistant c) Intermediate it grew at 16, meaning that it is not interpreted as intermediate anymore, its now resistant even if it didn't grow at 32ug/Ml You performed breakpoint testing on an organism with the following categories for a certain antibiotic S = /= 8ug/ml I = 16 ug/ml R = 32 ug/ml if the organism didn't grow at any concentration, what does this mean? a) Sensitive b) Resistant c) Intermediate T/F CNS are intrinsically more resistant to drugs than s. aureus TRUE What percent of S. aureus isolates are resistant against penicillins? What are you to do if you see a susceptible zone of inhibition? 90%; you should do a cefinase test because they likely contain the B-lactamase, its just inducible. How is MRSA resistant against oxacillin? a) Contains the MecA gene that produces a beta lactamase that targets oxacillin b) contains the MecA gene which altered the PBP to become PBP2a c) Contains the MecA gene which produces a channel protein that exports oxacillin once it enters the cell d) Contains the MecA gene that produces excess PBP which is too much for the oxacillin to overcome Which drugs will a MRSA NOT be sensitive to even if it shows that in AST testing? (3) Erythromycin (macrolide) Clindamycin (lincosamide) SXT (metabolic inhibitor) If you have an MRSA, how does reporting go for beta lactams if they show sensitivity in AST testing REPORT ALL BETA LACTAMS AND INHIBITOR COMBOS AS RESISTANT What two cephelasporins work against an MRSA? Ceftaroline and Ceftobiprole What is meant by homogenous vs heterozygous expression of MecA gene in an MRSA culture? What implications does this have when performing susceptibility testing?