Antibiotics

Question 1

_______________ is responsible for an estimated 2 million infections and 23,000 deaths per year in the united states.

Answer 1

Antibiotic resistance

Approximately half of outpatinet antibiotic prescribing in humans might be inappropriate.

At least 30% of outpatient antibiotic prescriptions in the United States are unnecessary.

Question 2

Urgent threats:

Answer 2

-Carbapenem-resistant Acinetobacter
-Candida auris (C. auris)
-Clostridioides difficile (C. difficile)
-Carbapenem-resistant Enterobacteriaceae (CRE)
-Drug-resistant Neisseria gonorrhoeae (N. gonorrhoeae)

Question 3

Serious threats:

Answer 3

-Drug resistant campylobacter
-drug resistant candida
-extended spectrum beta lactamase (ESBL) producing Enterobacteriaceae
-Vancomycin resistant enterococci (VRE)
-Multidrug resistant pseudomonas aeruginosa (P. aeruginosa)
-Drug resistant nontyphoidal salmonella
-Drug resistant shigella
-Methicillin resistant staphylococcus aureus (MRSA)
-Drug resistant streptococcus pneumoniae (S. pneumoniae)
-Drug resistant tuberculosis (TB)

Question 4

Concerning threats:

Answer 4

-Erythromycin resistant group A streptococcus
-Clindamycin resistant group B streptococcus

Question 5

Watch list:

Answer 5

-Azole resistant aspergillus fumigatus (A. fumigatus)
-Drug resistant mycoplasma genitalium (M. genitalium)
-Drug resistant Bordetella pertussis (B. pertussis)

Question 6

Mechanisms of antibiotic resistance:

Answer 6

-Modifications of the antibiotic molecule
-Decreased antibiotic penetration and efflux
-Changes in target sites
-Resistance due to global cell adaptations

Question 7

Antibiotic stewardship:

Answer 7

-to measure antibiotic prescribing

-to improve antibiotic prescribing by clinicians and use by patients so that antibiotics are only prescribed and used when needed.

-To minimize misdiagnoses or delayed diagnoses leading to the underuse of antibiotics

-to ensure that the right drug, dose, and duration are selected when an antibiotic is needed

Question 8

Bactericidal:

Answer 8

kills sensitive organisms so that number of viable organisms falls rapidly after exposure

Question 9

Bacteriostatic:

Answer 9

inhibits growth of bacteria but does not kill them

Question 10

Narrow antimicrobial spectrum:

Answer 10

agent is active against a single species or limited group of pathogens

Question 11

Broad antimicrobial spectrum:

Answer 11

agent is active against a wide range of pathogens

Question 12

Extended antimicrobial spectrum:

Answer 12

agents falls in between (intermediate)

Question 13

Mechanism of action:

Answer 13

-All beta-lactam antibiotics interfere with bacterial cell wall synthesis

-Inhibition of bacterial transpeptidase (also called penicillin-binding protein) which inhibits peptidoglycan cross-linking making cell wall synthesis impossible

-Generally, confers bactericidal activity

Question 14

Penicillin V:

Answer 14

-Narrow spectrum antibiotic

-Typically administered in an oral suspension

-Adverse effects include GI upset, nausea, vomiting, diarrhea, and rash. In rare instances can cause severe hypersensitivity reactions.

-Considered the drug of choice for group A streptococcal pharyngitis

-Dosed by weight for adults and children

-People over 27 kg: 300mg TID or 600mg BID PO for 10 days

-People 27 kg or under: 40mg/kg/day divided BID or TID for 10 days with a maximum daily dose of 750 mg

Question 15

Amoxicillin:

Answer 15

-An extended spectrum penicillin

-Essentially a modified version of penicillin that results in greater activity against additional gram-negative bacteria

-Generally well tolerated but can cause the same adverse effects as penicillin V

-Typically used more often asit is more palatable than penicillin V

-Dosed by body weight for all patients

-50mg/kg once daily or divided BID PO for 10 days with a maximum daily dose of 1000mg

Question 16

Cephalosporins:

Answer 16

-A very large group of antibiotics

-The different generations are used to define their antimicrobial spectrum

-Have greater structural diversity which is more resistant to beta-lactamases and increases their range of antimicrobial activity

Question 17

Cefadroxil:

Answer 17

-A first-generation cephalosporin

-May be used if treatment failure with penicillin or in individuals with nonimmediate hypersensitivity to penicillins

-Adverse effects include GI upset, nausea, vomiting, diarrhea, hypersensitivity (some cross-reactivity with penicillins)

Adults: 1g/gay PO as a single dose or divided BID for 10 days

Question 18

Ceohalexin:

Answer 18

-A first generation cephalosporin

-Same adverse effect profile as cefadroxil and may also be used if treatment failure with penicillins or in individuals with nonimmediate hypersensitivity to penicillins

-Also available as a suspension

Adults: 500mg BID PO for 10 days
Children: 40mg/kg/day divided BID PO for 10 days with a maximum daily dose of 1000 mg

Question 19

Protein synthesis inhibitors:

Answer 19

-Prokaryotic ribosomes are composed of a 30S and 50S subunit

-Eukaryotic mRNA translation proteins are far more complex than those in prokaryotic cells

Question 20

Macrolides:

Answer 20

-Inhibit peptidyl transferase which functions to link amino acids together int he growing peptide chain

-Also interferes with translocation (movement of the nucleotide from the A position to the P position to allow for reading the next spot on the mRNA)

-Confers bacteriostatic activity

Question 21

Azithromycin:

Answer 21

-An alternative for patients who are allergic to penicillin

-Less likely than other macrolide antibiotics to interact with other drugs

-Adverse effects include GI upset, nausea, vomiting, diarrhea, rash, QTc interval prolongation

Adults: 500mg PO for one day, then 250 mg PO daily for 4 days.

Children: 12 mg/kg PO for 5 days with a maximum daily dose of 500mg

Question 22

Clarithromycin:

Answer 22

-An alternative for patients who are allergic to penicillin

-Same adverse effect profile as azithromycin

-Also available as a suspension

-Increase the levels of some common drugs like atorvastatin, lovastatin, simvastatin, and prednisone

Adults: 250mg BID PO for 10 days
Children: 15mg/kg/day divided BID PO for 10 days with a maximum daily dose of 500mg

Question 23

Lacosamide:

Answer 23

-Interfere with translocation like macrolides but do not inhibit peptidyl transferase

-Approximately 4 times more likely to cause clostridium difficile infections compared to other antibiotics

-Generally bacteriostatic but can be bactericidal at high doses

Question 24

Clindamycin:

Answer 24

-An alternative for patients who are allergic to penicillin

-May be used for treatment in symptomatic patients with multiple, recurrent episodes of pharyngitis

Commonly causes diarrhea as an adverse effect. Increased risk of C. difficile colitis

Adult: 300mg TID PO for 10 days
Children: 21 mg/kg/day divided TID PO for 10 days with a maximum daily dose of 900mg

Question 25

Group A streptococcus pharyngitis:

Answer 25

-Antibiotic therapy is most beneficial for people who are at high risk of developing acute rheumatic fever and who have confirmed streptococcal infection

-Watchful waiting may be appropriate in patients at low risk for acute rheumatic fever as antibiotics have a minimal impact on the natural course of group A streptococcal pharyngitis

-According to evidence, antibiotics reduce duration of symptoms by approximately 16 hours

-Given the small benefit antibiotic therapy could be withheld for 48 -72 hours in adult patients with more severe symptoms

-Antibiotic therapy is not generally recommended for mild cases

Question 26

Which of the following antibiotics is suitable for use in a patient with an immediate hypersensitivity reaction to penicillin?

A. Amoxicillin
B. Cephalexin
C. Cefadroxil
D. Azithromycin

Answer 26

D. Azithromycin