Chapter: Antibiotics
1.

All of the following are true regarding penicillins EXCEPT

A. Most penicillins only cross the blood brain barrier when the meninges are inflamed.
B. Penicillins don’t require dosage adjustment in renal failure
C. Penicillins inhibit cross linkage of peptidoglycans in the cell wall
D. Piperacillin is a penicillin active against pseudomonas
E. Only about 5 to 10% of people with a past history of penicillin allergy have a reaction on re exposure
Answer» B. Penicillins don’t require dosage adjustment in renal failure
2.

Ciprofloxacin

A. Is a defluorinated analogue of nalidixic acid
B. Inhibits tropoisomerases 2 and 3
C. Has no gram positive cover
D. Has a bioavailability of 30%
E. May cause an arthropathy
Answer» E. May cause an arthropathy
3.

Resistance to B lactams

A. Can be due to an efflux pump
B. Is most commonly due to modification of the target PBPs
C. Does not involve penetration of drug to target PBPs
D. Infers resistance only to penicillinc
E. Can involve up to 5 different B lactamases
Answer» A. Can be due to an efflux pump
4.

Macrolides

A. Have enhanced activity at acidic pH
B. Have little activity against legionella
C. Have half lives which increase in patients with anuria
D. Induce cytochrome p450 enzymes
E. Are contraindicated in neonates
Answer» C. Have half lives which increase in patients with anuria
5.

Flucloxacillin

A. Is ineffective against streptococci
B. Is active against enterococci and anaerobes
C. Blocks transpeptidation and inhibits peptidoglycan synthesis
D. Is poorly absorbed orally
E. Has excellent penetration into CNS and prostate
Answer» C. Blocks transpeptidation and inhibits peptidoglycan synthesis
6.

All of the following inhibit nucleic acid synthesis EXCEPT

A. Norfloxacillin
B. Chloramphenicol
C. Trimethoprim
D. Rifampicin
E. Sulfasalazine
Answer» B. Chloramphenicol
7.

Which of the following is a second generation cephalosporin?

A. Cefaclor
B. Ceftazidime
C. Cephalexin
D. Cefotaxime
E. Cephalothin
Answer» A. Cefaclor
8.

Regarding the pharmacokinetics of the tetracyclines

A. Tetracyclines are 40 to 80 % bound by serum proteins
B. Absorption is enhanced by coadministration of antacids
C. Tetracyclines cross the blood brain barrier easily
D. Doxycycline is excreted predominantly by the kidney
E. Demeclocyline is a short acting tetracycline drug
Answer» A. Tetracyclines are 40 to 80 % bound by serum proteins
9.

All of the following are recognized adverse effects of isoniazid EXCEPT

A. Hepatitis
B. Peripheral neuropathy
C. Retrobulbar neuritis
D. Decreased phenytoin metabolism – increased phenytoin blood levels / toxicity
E. CNS toxicity
Answer» C. Retrobulbar neuritis
10.

Vancomycin

A. 90% of vancomycin is excreted by glomerular filtration
B. Inhibits proteinsynthesis in bacteria
C. Is bactericidal against gram negative bacilli
D. Is well absorbed from the GIT
E. One adverse reaction to infusions of vancomycin is the “blue man” syndrome
Answer» A. 90% of vancomycin is excreted by glomerular filtration
11.

Regarding mechanisms of antiviral drug action

A. blockage of viral uncoating is caused by rifampicin
B. Zidovudine is a protease inhibitor
C. Amantidine blocks viral DNA packaging and assembly
D. Indinavir is a reverse transcriptase inhibitor
E. Acyclovir inhibits viral DNA synthesis
Answer» E. Acyclovir inhibits viral DNA synthesis
12.

Regarding toxicity of antibiotics

A. Enamel dysplasia is common with aminoglycosides
B. Gray baby syndrome occurs with rifampicin use
C. Haemolytic anaemias can occur with sulphonamide use
D. Nephritis is the most common adverse reaction with isoniazid
E. Disulfiram like reaction can occur with macrolides
Answer» C. Haemolytic anaemias can occur with sulphonamide use
13.

Chloramphenicol

A. Does not penetrate the blood brain barrier
B. Must be administered parenterally
C. Can be safely used in premature infants
D. Can cause depression of bone marrow function
E. Can cause discoloration of developing teeth when given to children
Answer» D. Can cause depression of bone marrow function
14.

Spironolactone

A. Has a steroid structure
B. Is a partial agonist
C. Promotes sodium retention
D. Increases potassium loss
E. Is a loop diuretic
Answer» A. Has a steroid structure
15.

Which of the following drugs cause diuresis by the mechanisms indicated?

A. Ethanol – by preventing the reabsorption of sodium from renal tubular fluid
B. Digoxin – by inhibiting release of ADH
C. Dopamine – by inhibiting active transport of chloride over the entire length of the descending limb of the loop of Henle
D. Frusemide – by inhibiting carbonic anhydrase
E. Chlorothiazide – by inhibiting active sodium transport in the ascending limb of the loop of Henle
Answer» E. Chlorothiazide – by inhibiting active sodium transport in the ascending limb of the loop of Henle
16.

All of the following antibiotics bind to the 50S subunit of the ribosome thereby inhibiting proteinsynthesis EXCEPT

A. Chloramphenicol
B. Erythromycin
C. Linezolid
D. Doxycycline
E. Clindamycin
Answer» D. Doxycycline
17.

Pharmacokinetics of doxycycline

A. 20% bound by serum proteins
B. 60-70% absorption after oral administration
C. Absorption is impaired by divalent cations, Al3+, and antacids
D. Widely distributed especially into the CSF
E. Is eliminated via renal mechanisms
Answer» C. Absorption is impaired by divalent cations, Al3+, and antacids
18.

Which of the following inhibits DNA gyrase?

A. Penicillin
B. Trimethoprim
C. Chloramphenicol
D. Ciprofloxacin
E. Gentamicin
Answer» D. Ciprofloxacin
19.

Resistance to Penicillin and other β lactams is due to

A. Modification of target PBPs
B. Impaired penetration of drug to target PBPs
C. Presence of an efflux pump
D. Inactivation of antibiotics by β lactamase
E. All of the above
Answer» E. All of the above
20.

All of the following are recognised adverse effects of isoniazid EXCEPT

A. Hepatitis
B. Peripheral neuropathy
C. Retrobulbar neuritis
D. ↓ Phenytoin metabolism → ↑ Phenytoin blood levels and toxicity
E. CNS toxicity
Answer» C. Retrobulbar neuritis
21.

Regarding fluoroquinolones

A. Ciprofloxacin is ineffective in the treatment of gonococcus
B. Norfloxacin and Ciprofloxacin are predominantly faecally excreted
C. Norfloxacin and Ciprofloxacin have long half lives (12 hours)
D. They have poor oral bioavailability
E. May damage growing cartilage in children less than 18 years of age
Answer» E. May damage growing cartilage in children less than 18 years of age
22.

Vancomycin

A. Is never orally administered as it is poorly absorbed from the GIT
B. Binds to the 30S unit on the ribosome and inhibits protein synthesis
C. 60% of vancomycin is excreted by glomerular filtration
D. Parenteral vancomycin is commonly used for treatment of infections caused by methicillin susceptible staphylococci
E. Adverse reactions to vancomycin are encountered in about 10% of patients
Answer» E. Adverse reactions to vancomycin are encountered in about 10% of patients
23.

Regarding the “azole” group of antifungals

A. Fluconazole has low water solubility
B. Ketoconazole may be given IV/PO
C. Itraconazole undergoes renal elimination
D. Clotrimazole is the treatment of choice for systemic candidiasis – given orally
E. They work by reduction of ergosterol synthesis by inhibition of fungal cytochrome P450 enzymes
Answer» E. They work by reduction of ergosterol synthesis by inhibition of fungal cytochrome P450 enzymes
24.

The fluoroquinolones

A. May be administered to patients with severe campylobacter infection
B. Work by inhibiting dihydrofolate reductase
C. Have little effect against gram positive organisms
D. Are heavily metabolised in the liver
E. Are safe to give to breast feeding mothers
Answer» A. May be administered to patients with severe campylobacter infection
25.

Clindamycin

A. Inhibits bacterial cell wall synthesis
B. Is often used for prophylaxis of endocarditis in patients with Valvular disease who are undergoing dental procedures
C. Penetrates through BBB into CSF well
D. Works well against enterococci and gram negative aerobic organisms
E. Is 10% protein bound
Answer» B. Is often used for prophylaxis of endocarditis in patients with Valvular disease who are undergoing dental procedures
26.

Which of the following is a second generation cephalosporin?

A. Ceftazidime
B. Cephalothin
C. Cefotaxime
D. Cefaclor
E. Cephalexin
Answer» D. Cefaclor
27.

The cephalosporin with the highest activity against gram positive cocci is

A. Cefaclor
B. Cephalothin
C. Cefuroxime
D. Cefepime
E. Cefotaxime
Answer» B. Cephalothin
28.

Regarding the penicillins

A. Penicillin ix excreted into breast milk to levels 3-15% of those present in the serum
B. Absorption of amoxyl is impaired by food
C. Benzathine penicillin is given PO
D. Penicillins are 90% excreted by glomerular filtration
E. Dosage of nafcillin should be adjusted in the presence of renal failure
Answer» A. Penicillin ix excreted into breast milk to levels 3-15% of those present in the serum
29.

Rifampicin

A. Inhibits hepatic microsomal enzymes
B. Inhibits DNA synthesis
C. Is bactericidal for mycobacteria
D. Is not appreciably protein bound
E. Is predominantly excreted unchanged in the urine
Answer» C. Is bactericidal for mycobacteria
30.

Regarding resistance to antibiotics

A. Penicillinases cannot inactivate cephalosporins
B. Macrolides can be inactivated by transferases
C. Mutation of aminoglycoside binding site is its main mechanism of resistance
D. Tetracycline resistance is a marker for multidrug resistance
E. Resistance to antibiotics is rarely plasmid encoded
Answer» C. Mutation of aminoglycoside binding site is its main mechanism of resistance
31.

Concerning toxicity of antibiotics

A. Enamel dysplasia is common with aminoglycosides
B. Grey Baby Syndrome occurs with rifampicin use
C. A disulfiram like reaction can occur with macrolides
D. Haemolytic anaemias can occur with sulphonamide use
E. Nephritis is the most common adverse reaction with isoniazid
Answer» D. Haemolytic anaemias can occur with sulphonamide use
32.

Which of the following is considered to be bacteriostatic?

A. Penicillin
B. Chloramphenicol
C. Ciprofloxacin
D. Cefoxitin
E. Tobramycin
Answer» B. Chloramphenicol
33.

Half life of amphotericin B is

A. 2 seconds
B. 20 minutes
C. 2 hours
D. 2 weeks
E. 2 months
Answer» D. 2 weeks
34.

Regarding antiseptic agents – all of the following are true EXCEPT

A. Sodium hypochlorite is an effective antiseptic for intact skin
B. Potassium permanganase is an effective bactericidal agent
C. Formaldehyde may be used to disinfect instruments
D. Chlorhexidine is active against gram positive cocci
E. Ethanol is an effective skin antiseptic because it denatures microbial proteins
Answer» A. Sodium hypochlorite is an effective antiseptic for intact skin
35.

Ciprofloxacin

A. Is a defluorinated analogue of nalidixic acid
B. Inhibits tropoisomerases 2 and 3
C. Has no gram positive cover
D. Has bioavailability of 30%
E. May cause an arthropathy
Answer» D. Has bioavailability of 30%
36.

Aminoglycosides

A. Have a β lactam ring
B. Can produce neuromuscular blockade
C. Are DNA gyrase inhibitors
D. Normally reach high CSF concentrations
E. Have good oral absorption but high first pass metabolism
Answer» B. Can produce neuromuscular blockade
37.

Ribosomal resistance occurs with

A. Sulphonamides
B. Penicillin
C. Fluoroquinolones
D. Macrolides
E. Trimethoprim
Answer» D. Macrolides
38.

Regarding antivirals

A. Delvindine is a nucleoside reverse transcriptase inhibitor (NRTI)
B. Zidovudine (AZT) is a non nucleoside reverse transcriptase inhibitor (NNRTI)
C. NRTIs activate HIV-1 reverse transcriptase
D. Abacavir is a protease inhibitor
E. NRTIs require intracytoplasmic activation to the triphosphate form
Answer» E. NRTIs require intracytoplasmic activation to the triphosphate form
39.

All of the following are true regarding metronidazole EXCEPT

A. It is used to treat giardia
B. It causes a metallic taste in the mouth
C. It inhibits alcohol dehydrogenase
D. It is used to treat gardnerella
E. It is useful against trichomonoas vaginalis
Answer» C. It inhibits alcohol dehydrogenase
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