Antibacterials 5 Flashcards by Gopu Premrajan

Chloramphenicol is a ____________ spectrum and inhibits _________

Broad spectrum; protein synthesis

Bactiostatic

How well did you know this?

Not at all

Perfectly

Chloramphenicol binds to ______ and inhibits __________

50S; peptidyltransferase

How well did you know this?

Not at all

Perfectly

What is an adverse effect of chloramphenicol?

Bone marrow toxicity

How well did you know this?

Not at all

Perfectly

Presence of ___________ codes for resistance against chloramphenicol

Acetyltransferase

How well did you know this?

Not at all

Perfectly

What is the method of resistance for chloramphenicol?

presence of a factor that codes for acetyltransferase

- changes in membrane permeability

How well did you know this?

Not at all

Perfectly

When is chloramphenicol used clinically?

Only for serious infections due to the severe toxicity (last resort)

used against VRE
eye drops

How well did you know this?

Not at all

Perfectly

Chloramphenicol inhibits ________ and thus can have a lot of drug interactions

Hepatic oxidases (3A4 and 2C9)

How well did you know this?

Not at all

Perfectly

What is a unique adverse effect of choloramphenicol?

Gray baby syndrome (cyanosis) due to drug accumulation because they don’t have well developed livers yet

How well did you know this?

Not at all

Perfectly

MOA of clindamycin

Same as macrolides: binds to 50S and blocks translocation

How well did you know this?

Not at all

Perfectly

clindamycin is used against _________

Primarily Gram positive anaerobic (and aerobic) bacteria and bacteriodes

How well did you know this?

Not at all

Perfectly

Most _______________ and ________are intrinsically resistance to clindamycin

Gram negative aerobes; enterococcus

How well did you know this?

Not at all

Perfectly

Clindamycin has cross resistance with ______

Macrolides

How well did you know this?

Not at all

Perfectly

Can clindamycin used to treat MRSA?

Yes

How well did you know this?

Not at all

Perfectly

Clinical applications of clindamycin

Used as an alternative for pencillin allergic patients (like macrolides)

How well did you know this?

Not at all

Perfectly

Adverse effects of clindamycin

fatal pseudomembranous colitis (C difficile)
GI irritations
skin rashes
neutropenia and impaired liver function

How well did you know this?

Not at all

Perfectly

What antibiotics can cause pseudomembranous colitis?

clindamycin

- ampicillin

How well did you know this?

Not at all

Perfectly

Drugs that are in the class of streptogranins (protein synthesis inhibitors)

Quinupristin and Dalfopristin

How well did you know this?

Not at all

Perfectly

Which antibacterial have a postantibiotic effect?

Stretogranins and Aminoglycosides

How well did you know this?

Not at all

Perfectly

MOA of streptogranins

Bind to 50S ribosome

How well did you know this?

Not at all

Perfectly

Clinical applications of streptogramins

gram positive cocci
multi drug resistance bacteria (MRSA, VRE)
can attack intracellularly because they penetrate macrophages and polymorphonucleocytes (PMP’s)

How well did you know this?

Not at all

Perfectly

Streptogramins can have drug interactions because they can inhibit _________

CYP3A4

How well did you know this?

Not at all

Perfectly

Linezolid is mainly bacteriostatic but is bacteriocidal against ______ and _________

Streptococci and Clostridum perfringens

How well did you know this?

Not at all

Perfectly

MOA of linezolid

Inhibits the 70S invitation complex by binding to the 23S rRNA of the 50S subunit

How well did you know this?

Not at all

Perfectly

Linezolid has a similar MOA as _______ but what is the difference?

Aminoglycosides; they both inhibit the initiation complex except Aminoglycosides bind to the 30S subunit

How well did you know this?

Not at all

Perfectly

Clinical applications of linezolid

- mainly gram positive organisms including MRSA and VRE | - moderate activity against mycobacterium tuberculosis

Linezolid is also a weak ______

MAOI

Linezolid is well tolerated for short term but what are some long term administration adverse effects?

- bone marrow suppression especially thrombocytopenia - optic and peripheral neuropathy - lactic acidosis - serotonin Syndrome (it is a weak MAOI)

Fidaxomicin has activity against _________

ONLY gram positive; NO action on gram negative

MOA of fidaxomicin

Inhibits protein synthesis by binding to bacterial RNA polymerase

Clinical applications of fidaxomicin

Treatment of C. Difficile in adults

_______________ is a bacterial protein synthesis inhibitors that is used in people > 18 because safety and effectiveness in people younger have not been established

Fidaxomicin

Mupirocin’s route of administration is __________ and has activity against ________

Topical/intranasal; | Most gram positive cocci including MRSA

Mupirocin binds to _________ and inhibits protein synthesis

Bacterial isoleucyl tRNA synthetase

Clinical applications of mupirocin

Intranasally: eradicate nasal colonization of MRSA in adult patients and healthcare workers Topically: impetigo or secondary infected traumatic skin lesions

_____________ (skin condition) is treated using mupirocin

Impetigo

Adverse effects of mupironcin

Mainly local and dermatology effects such as burning, edema, tenderness, dry skin, etc

Classes of drugs that affect nucleic acid synthesis

- fluoroquinolones - sulfonamides - trimethoprim

Describe the type of bacteria that is mainly affected as you move from 1st to 4th generation of fluoroquinoles

↑ activity against gram positive and ↓ activity against gram negative Opposite of cephalosporins

MOA of fluoroquinolones

Broad spectrum, bacteriocidal and enter bacteria via porins Inhibits DNA replication via topoisomerase II and topoisomerase IV

Fluoroquinoles inhibit ____________ and _________

Topoisomerase II and IV

Mechanism of resistance against fluoroquinoles

- chromosomal mutation that encode subunits of DNA gyrase and topoisomerase IV or ones that regulate expression of efflux pumps - cross resistance with other drugs

What drug is a 1st generation fluoroquinolone

Nalidixic acid

What is a 2nd generation fluorquinolone drug and what is its antimicrobial spectrum

Ciprofloxacin; | Synergistic activity with β lactams

What is a 3rd generation fluoroquinolone drug and what does it have good activity against

Levofloxacin; excellent activity against S. Pneumonia

What are the two 4th generation fluoroquinolone drugs

Moxifloxacin and gemifloxacin

What are the three drugs that are used against meningitis

- ceftriaxone - rifampin - ciprofloxacin

What are the respiratory fluoroquinolones

3rd and 4th generation: - levofloxacin - moxifloxacin - gemifloxacin Can be used to treat atypical pneumonia because those bacteria dont have cell walls

When are respiratory fluoroquinolones used for treatment

Used to treat pneumonia but when first line agents have failed (macrolides w/ or w/o tetracyline) Or in the presence of comorbidities

___________ and _______ absorption are affected by divalent cations

Fluoroquinoles and tetracyclines

Most fluoroquinolones are excreted via __________ except ________

Renal; moxifloxacin

Which fluoroquinolone would you prescribe to a patient with renal dysfunction

Moxifloxacin because it is excreted in the bile

What are the adverse effects of fluorquinolones

- Connective tissue problems (avoid in pregnancy, nursing mothers and under 18) - peripheral neuropathy - QT prolongation - GI distress - CNS, rash, photosensitivity - superinfection

Connective tissue problems is an adverse effect to taking ______

Fluoroquinolones

What type of patients CANNOT take fluoroquinolones?

Pregnant, nursing mothers and patients under 18 years old

What drugs have an adverse effect of QT prolongation

- fluoroquinolones: moxifloxacin, gemifloxacin, levofloxacin - macrolides

______, _______, and ______ enhance the toxicity of fluoroquinolones

Theophylline, NSAIDS and corticosteroids

What are the drug interactions of 3rd and 4th generation fluoroquinolones

- ↑ serum levels of: warfarin, caffeine and cyclosporine

What are the drugs in the sulfonamide family and what kind of bacteria do they act against

- sulfamethoxazole - sulfadiazine - sulfasalazine Bacteristatic against gram positive and negative

MOA of sulfanomides and how is it specific to bacteria?

Inhibits bacterial folic acid synthesis; They are synthetic analogs of PABA and thus are competitive inhibitors of dihydropteroate synthase (this enzyme is only used by bacteria to create folate)

Sulfonamides are compete with PABA for the enzyme ________

Dihydropteroate synthetase

Mechanisms of resistance against sulfonamides

- altered dihydropteroate synthase - ↓ cellular permeability - enhanced PABA production - ↓ intracellular drug accumulation

What are some clinical applications of sulfonamides and what are they used for?

Topical: ocular and burns Oral: simple UTI’s

What is sulfasalazine used to treat?

- ulcerative colitis - enteritis - IBD (This one is oral NON absorbable)

Unique adverse effects of sulfonamides

- Crystalluria (nephrotoxicity) - hypersensitivity reactions - hematopoietic disturbances (especially in those with G6PD deficiency) - kernicterus in newborns and infants

What drugs can cause kernicterus

Ceftriaxone and sulfonamides

Sulfonamides can displace drugs such as _____, ______, and _______ from albumin

Warfarin, phenytoin, and methotrexate

Trimethroprim is a potent inhibitor of _________

Bacterial dihydrofolate reductase | Inhibits purine, pryrimidine, and AA synthesis