Protein Synthesis Inhibitors

Question 1

A minimally absorbed macrolide used to treat Clostridium difficile infections by binding to the sigma subunit of RNA polymerase to inhibit bacterial protein synthesis

Answer 1

Fidaxomicin

Question 2

Experts recommend supplemental ________ (vitamin) for patients treated with linezolid.

Answer 2

pyridoxine (vit B6)

Question 3

This prevents formation of the ribosome complex that initiates protein synthesis by uniquely binding on 23S ribosomal RNA of the 50S subunit, resulting in no cross-resistance with other drug classes.

Answer 3

Linezolid (an oxazolidinone)

Question 4

Broadest of the broad antibiotics

Answer 4

Tetracycline

Question 5

The active moiety of a next-generation oxazolidinone more highly protein-bound (70–90%) than linezolid (31%)

Answer 5

Tedizolid

Question 6

________________ is the most common manifestation of linezolid toxicity (seen in approximately 3% of treatment courses), particularly when the drug is administered for longer than 2 weeks.

Answer 6

Thrombocytopenia

The principal toxicity of linezolid is hematologic; the effects are reversible and generally mild.

Question 7

Subclass of Protein Synthesis Inhibitors that prevents bacterial protein synthesis by binding to the 30S ribosomal subunit to block attachment of aminoacyl-tRNA to acceptor site

Answer 7

Tetracycline

Question 8

Tetracycline that is used to treat community acquired pneumonia and exacerbations of bronchitis, requiring no dosage adjustment for those with renal insufficiency.

Answer 8

Doxycycline

Question 9

This tetracycline is rarely used as an antibacterial, but it has been used off-label in the treatment of inappropriate secretion of antidiuretic hormone because of its inhibition of antidiuretic hormone in the renal tubule

Answer 9

Demeclocycline
**D for diuresis!!!

Question 10

A very broad tetracycline that is not affected by the common resistance determinants, and its elimination is primarily biliary; hence, no dosage adjustment is needed for patients with renal insufficiency.

Answer 10

Tigecycline

Question 11

TC that can eradicate the meningococcal carrier state, but because of side effects and resistance of many meningococcal strains, ciprofloxacin or rifampin is preferred.

Answer 11

Minocycline

Question 12

Irreversible protein synthesis inhibitor with the following effects:
- block of formation of the initiation complex
- miscoding of amino acids in the emerging peptide chain due to misreading of the mRNA; and
- block of translocation on mRNA.

Answer 12

Aminoglycoside

Question 13

Which ribosomal subunit do aminoglycosides bind?

Answer 13

30s

Question 14

______ extracellular pH and _______ (aerobic/anaerobic) conditions inhibit aminoglycoside transport by reducing the gradient.

Answer 14

Low extracellular pH and anaerobic conditions

Question 15

This is the principal type of resistance encountered clinically for aminoglycosides is the production of a transferase enzyme that inactivates the aminoglycoside
by which 3 modifications?

Answer 15

adenylylation, acetylation, or phosphorylation.

Question 16

The enterococcal enzyme that modifies gentamicin is a bifunctional enzyme that also inactivates amikacin, netilmicin, and tobramycin but not ________ which is modified by a different enzyme. This is why some gentamicin-resistant enterococci are susceptible to:

Answer 16

streptomycin

Question 17

This is added to vancomycin for enterococcal endocarditis with serious allergy to penicillin

Answer 17

gentamicin

Question 18

Most serious toxic effect of Streptomycin

Answer 18

Vestibular disturbance (ototoxicity)

Question 19

The prototype drug for macrolides

Answer 19

Erythromycin

Question 20

The binding site of this antimicrobial subclass is near the peptidyltransferase center, and this prevent peptide chain elongation (ie, transpeptidation) by blocking of the polypeptide exit tunnel, blocking peptide bond formation

Answer 20

Macrolide

Question 21

Enzymes responsible for the decreased affinity of macrolide and clindamycin on the attachment site resulting to resistance

Answer 21

methyltransferases

Question 22

Enzymes produced by Enterobacteriaceae that hydrolyze macrolides causing drug-inactivation or resistance

Answer 22

esterases

Question 23

This the mechanism of resistance against erythromycin that results from modification of the ribosomal binding site by chromosomal mutation or by a macrolide-inducible or constitutive methylase.

Answer 23

Ribosomal protection

Question 24

Prophylaxis against endocarditis during dental procedures with valvular heart disease

Answer 24

Erythromycin

Question 25

Macrolide that is more active than erythromycin against Mycobacterium avium complex (MOTB)

Answer 25

Clarithromycin

Question 26

A traditional drug of choice in corynebacterial infections (diphtheria, corynebacterial sepsis, erythrasma) and in respiratory, neonatal, ocular, or genital chlamydial infections.

Answer 26

Erythromycin

Question 27

Macrolide that may be associated with a small increased risk of cardiac death

Answer 27

Azithromycin

Question 28

Macrolide that may be useful for gastroparesis due to its side effect of direct stimulation of gut motility.

Answer 28

Erythromycin

Question 29

An off-label indication for this macrolide is adynamic ileus as it stimulates motilin receptors

Answer 29

Clarithromycin (or Azithromycin)

Question 30

Macrolide that is active against M. avium complex and T. gondii, slightly more active against H. influenzae, and highly active against Chlamydia sp. compared to other macrolides

Answer 30

Azithromycin

Question 31

True or False: Azithromycin penetrates into most tissues especially cerebrospinal fluid

Answer 31

False:
azithromycin penetrates into most tissues (except cerebrospinal fluid) and phagocytic cells extremely well, with tissue concentrations exceeding serum concentrations by 10- to 100-fold.

Question 32

Macrolide antibiotics PROLONG the electrocardiographic QT interval due to an effect on _______ ion channels, leading to torsades de pointes arrhythmia

Answer 32

potassium

Question 33

May be considered for treatment of serious rickettsial infections such as typhus and Rocky Mountain spotted fever. It is an alternative to a β-lactam antibiotic for treatment of bacterial meningitis occurring in patients who have major hypersensitivity reactions to penicillin.

Answer 33

Chloramphenicol

Question 34

The active metabolites of clindamycin are excreted in ________

Answer 34

bile and urine

Question 35

______________, sometimes in combination with an aminoglycoside or cephalosporin, is used to treat penetrating wounds of the abdomen and the gut; infections originating in the female genital tract, eg, septic abortion, pelvic abscesses, or pelvic inflammatory disease; and lung and periodontal abscesses.

Answer 35

Clindamycin

Question 36

Quinupristin-dalfopristin is a combination of two streptogramins—quinupristin, a streptogramin B, and dalfopristin, a streptogramin A—in a ________ ratio

Answer 36

30:70 ratio

Question 37

Cause of resistance for dalfopristin A

Answer 37

active reflux pump

Question 38

Cause of resistance for B-subunit of stretogrammins

Answer 38

Methyltransfers in MLS-B type resistance

Question 39

This is approved for treatment of infections caused by staphylococci or by vancomycin-resistant strains of E faecium, but not E faecalis, which is intrinsically resistant, probably because of an efflux-type resistance mechanism.

Answer 39

Quinupristin-dalfopristin

Question 40

Drug that binds reversibly to the 50S subunit of the bacterial ribosome and inhibits peptide bond formation, and clinically significant resistance to it is due to production of acetyltransferase, a plasmid-encoded enzyme that inactivates the drug.

Answer 40

Chloramphenicol

Question 41

A rare consequence of chloramphenicol administration by any route which tends to be irreversible and is an idiosyncratic reaction unrelated to dose. Due to the severity of this reaction, a boxed warning has been added to its U.S. labeling.

Answer 41

Aplastic anemia

Question 42

The toxic effect chloramphenicol among infants that causes vomiting, flaccidity, hypothermia, shock, and vascular collapse; avoided by limiting dosage to 50 mg/kg/d

Answer 42

Gray baby syndrome

Question 43

DOC for filariasis, loiasis and tropical eosinophilia

Answer 43

Diethylcarbamazine citrate

Question 44

Drug that acts directly by killing Wolbachia, an intracellular bacterial symbiont of filarial parasite

Answer 44

Doxycycline

Question 45

The recommended alternative agent by CDC for primary and secondary syphilis in patients with penicillin allergy

Answer 45

Doxycycline