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Antibiotics
Antibiotics for Medical Students
28
Microbiology
Graduate
11/21/2011

Additional Microbiology Flashcards

 


 

Cards

Term

Sulfonamides

- SMX

-Sulfisoxazole

-Sulfadiazine

Definition

- Bactericidal

- Available in combination with TMP

 

- Spectrum of activity:

Gram (+) ; not Enterococci

Gram (-) ; limited to respiratory pathogens

Poor against atypicals or anaerobes



E.coli, Chlamydia, Nocardia, PCP, MRSA, Simple UTIs 

 

Toxicity: cross allergenicity, hyperkalemia, bone marrow suppression, Warfarin binding competition

 

Term
Which antibiotics are folate synthesis inhibitors?
Definition

Sulfonamides

Trimethoprim

Term
Trimethoprim
Definition

- Bacteriostatic

- Often used in combination with sulfonamides as TMP-SMX

 

Spectrum of activity:

Only Staphylococcus and E.coli

 

Recurrent UTIs, Shigella, Salmonella, PCP, Ocular infections

 

Toxicity: Bone marrow suppression resulting in megaloblastic anemia, leukopenia, granulocytopenia

Term
Which antibiotics inhibit protein synthesis?
Definition

Clindamycin

Chloramphenicol

Linezolid

Aminoglycosides

Macrolides

Tetracyclines

Tigecycline

 

(CCLAMTT)

Term

Mechanism of resistance:

Chloramphenicol

Definition
Plasmid-encoded acetyltransferase that inactivates the drug
Term
Chloramphenicol
Definition

- Bacteriostatic

- Binds to 50s ribosomal subunit

- Excellent CNS penetration

 

Spectrum of activity:

Gram (+) ; MRSA and some VRE

Gram (-) ; common respiratory pathogens

Most anaerobes and atypicals


Meningitis (SHiN), Resistant Gram (+)


Toxicity: SEVERE, anemia, Grey Baby syndrome, aplastic anemia

 

Term
What is unique about chloramphenicol?
Definition
It has excellent CNS penetration; thus, it can be used to treat meningitis
Term

Mechanism of resistance:

Aminoglycosides

Definition
Acetylation, phosphorylation, or adenylation of key amino and -OH groups via bacterial enzymes
Term

Aminoglycosides

- Gentamicin

- Streptomycin

- Neomycin

Definition

- Bactericidal

- Bind to the 30s ribosomal subunit, misreading of genetic code

- Require OXYGEN for uptake

 

Spectrum of activity:

Gram (-)

Limited Gram (+) but synergistic when combined with β-lactam

Part of TB therapy

NO ANAEROBIC/ATYPICAL activity

 

 

 

 

GRAM (-) infections

Used in combination to treat Gram (+)

 

Toxicity: Nephrotoxicity, Ototoxicity, Teratogen (NOT)

 

Term

Mechanism of resistance:

Tetracyclines

Definition

Production of efflux proteins(increased efflux)

Production of ribosomal protection proteins (decreased uptake)

Term

Tetracyclines

- Tetracycline

- Doxycycline

Definition

- Bacteriostatic

- Doxycycline can be used in patients with renal failure

- DO NOT take with dairy produces, antacids, vitamins/mineral supplements because they prevent absorption in the gut 

 

Spectrum of activity:

Gram (+) ; some MRSA

Gram (-) ; common respiratory pathogens

Oral anaerobes and atypicals

 

Rickettsia, Chlamydia, Syphilis, Borrelia, H.pylori, M.pneumoniae, B.anthracis

 

Toxicity: Photosensitivity, do not take with chelating agents, GI distress, inhibition of bone growth in children

Term
Tigecycline
Definition

- Ribosomal 30s subunit inhibition

- Similar to tetracyclines

 

Spectrum of activity:

Gram (+)

Gram (-)

Anaerobes

 

SSTIs, Intra-abdominal infections

 

Toxicity: hyperemesis

Term

Mechanism of resistance:

Clindamycin

Definition
Alteration of the 50s subunit
Term
Clindamycin
Definition

- Bacteriostatic

- Binds to 50s ribosomal subunit

 

Spectrum of activity:

Anaerobes

Gram (+); some MRSA and enterococci

 

Anaerobes = Bacteroides fragilis, Clostridium perfringens

abscesses, acne, PID

 

Toxicity: can cause C.diff overgrowth

Term
Linezolid
Definition

- Bacteriostatic against Staph, Entero

- Bactericidal against Strep

- Prevents tRNA binding to A site of ribosome

 

Spectrum of activity:

Gram (+)

Some Gram (-)

 

Gram (+) and VRE infections

 

Toxicity: hypertension, serotonin syndrome

 

Term

Mechanism of resistance:

Macrolides

Definition
Alteration of macolide ribosome binding site (23s) via methylation
Term

Macrolides

- Clarithromycin

-Azithromycin

- Erythromycin

Definition

- Bacteriostatic

- Binds to 50s ribosomal subunit

 

Spectrum of activity:

(SHAM)

Strep, Staph, Enterococci

H. pylori

Atypicals and anaerobes

Mycobacteria

 

Atypical pneumonias (Chlamydia, Legionella, Mycoplasma),

Gram (+) bacteria, Neisseria

 

Toxicity: GI upset, potency, hepatic clearance, CYP inhibitors, can prolong QTc interval

 

Term

Ketolides

- Telithromycin

Definition

- 2nd generation macrolide

- Able to bind at more sites than macrolides

- Active against resistant strains

 

Spectrum of activity:

Respiratory tract infections

Atypical bacteria

 

Atypical bacteria, Macrolide resistant strains

 

Toxicity: highly toxic, same as macrolides

Term
Beta-Lactam Antibiotics
Definition

Penicillins

 

Cephalosporins

 

Carbapenems

 

Monobactams

Term

General considerations:

Penicillins

Definition

- Bactericidal

- No Atypical Activity

- Inactivation of degrading enzymes (Penicillin-resistant)

- Alterations in PBP enzyme targets (MRSA)

- Well-tolerated

- May need dose reductions due to renal elimination

(exc. Nafcillin, Oxacillin)

Term

Natural Penicillins

- Penicillin V

- Penicillin G

- Procaine

- Benzathine

Definition

- Beta-lactam

- Method of resistance is the production of Beta-Lactamases

 

Spectrum of activity:

Gram (+) aerobes ; Strep and Entero

Treponema pallidium

 

Strep and Syphilis, Meningitis, Endocarditis

 

 

Term

Aminopenicillins

- Ampicillin

-Amoxicillin

- Unasyn

- Augmentin

Definition

- Combined with Beta-Lactamase inhibitors, they become more effective

 

Spectrum of activity:

Gram (+) ; Strep, Enterococci

Limited Gram (-)

Combined: Improved Gram (+), more Gram (-) and some anaerobic activity

 

SSTIs, Otitis, Lyme disease (2nd line tx)

 

 

Term

Anti-Staphylococcal Penicillins

- Nafcillin, Oxacillin

- Cloxacillin, Dicloxacillin

Definition

Spectrum of Activity:

Limited to only Staph and Streptococci

 

Osteomyelitis, SSTIs


Toxicity: Some hepatic elimination, mild elevations in liver function enzymes

Term

Anti-Pseudomonal Penicillins

- Piperacillin

- Piperacillin/Tazobactam

Definition

- Less Gram (+) activity

 

Spectrum of activity:

Gram (-)

Anaerobes

Addition of the beta-lactamase inhibitor improves activity

 

Broad-spectrum empiris or targeted therapy of nosocomial infections

 

 

Term

Clinical considerations:

Cephalosporins

Definition

ALL cephalosporins have NO activity against enterococci

 

MOST cephalosporins have NO activity against anaerobes

 

MOST need to have doses reduced due to renal metabolism

 

Beta-lactam rash considerations

Term

1st Generation Cephalosporins

- Cefazolin

- Cephalexin

Definition

Spectrum of activity:

Gram (+) ; no enterococci or MRSA

 

SSTIs, Tonsilitis, UTIs

 

 

Term

2nd Generation Cephalosporins

- Cefuroxime

- Cefotetan

- Cefoxitin

Definition

Spectrum of activity:

Gram (+)

Some beta-lactamase Gram (-)

 

UTIs, sinusitis, Lyme Disease (2nd line tx)

 

Term

3rd Generation Cephalosporins

- Ceftazidime

- Ceftriaxone

 

Definition

Spectrum of activity:

Gram (-) ; except Pseudomonas

Ceftazidime has Pseudomonal activity

less Gram (+) activity

 

All of the activity of other cephalosporins

+

Meningitis, UTIs, chronic Lyme disease

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