Page 231 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

Microbiology ` microbiology—systems Microbiology ` microbiology—aNtimicrobials SEcTioN ii 187

` microbiology—aNtimicrobials

Antimicrobial therapy

DNA INTEGRITY mRNA SYNTHESIS
FOLIC ACID SYNTHESIS (via free radicals) (RNA polymerase) GYRASE
AND REDUCTION
(DNA methylation) Metronidazole Rifampin Fluoroquinolones
Ciprofloxacin
Levofloxacin, etc
Sulfonamides – –
Sulfamethoxazole BACTERIAL CELL Quinolone
Sulfisoxazole PABA Nalidixic acid
Sulfadiazine –
–
Trimethoprim DNA gyrase
– DNA
RNA
MEMBRANE INTEGRITY polymerase
DHF PROTEIN SYNTHESIS
Daptomycin (gram ) – 50S SUBUNIT
Polymyxins (gram ) mRNA
Chloramphenicol
Ribosomes Clindamycin
CELL WALL SYNTHESIS
THF 50S 50S Linezolid
PEPTIDOGLYCAN SYNTHESIS 30S 50S 30S Macrolides
30S – Azithromycin
Glycopeptides Cell membrane Clarithromycin
Vancomycin – Erythromycin
Bacitracin Cell wall Streptogramins
– Quinupristin
Dalfopristin
PEPTIDOGLYCAN CROSS-LINKING
30S SUBUNIT
Penicillinase-sensitive penicillins Antipseudomonal Carbapenems
Penicillin G, V Ticarcillin Imipenem Aminoglycosides Glycylcycline
Ampicillin Piperacillin Meropenem – Gentamicin Tigecycline
Amoxicillin Cephalosporins (I-V) Ertapenem Neomycin Tetracyclines
Penicillinase-resistant penicillins 1st—Cefazolin, etc Doripenem Amikacin Tetracycline
Oxacillin 2nd—Cefoxitin, etc Monobactams Tobramycin Doxycycline
Nafcillin 3rd—Ceftriaxone, etc Aztreonam Streptomycin Minocycline
Dicloxacillin 4th—Cefepime
5th—Ceftaroline

Penicillin G, V Penicillin G (IV and IM form), penicillin V (oral). Prototype β-lactam antibiotics.
mecHaNism D-Ala-D-Ala structural analog. Bind penicillin-binding proteins (transpeptidases).
Block transpeptidase cross-linking of peptidoglycan in cell wall.
Activate autolytic enzymes.
cliNical Use Mostly used for gram ⊕ organisms (S pneumoniae, S pyogenes, Actinomyces). Also used for gram ⊝
cocci (mainly N meningitidis) and spirochetes (mainly T pallidum). Bactericidal for gram ⊕ cocci,
gram ⊕ rods, gram ⊝ cocci, and spirochetes. β-lactamase sensitive.

aDVerse eFFects Hypersensitivity reactions, direct Coombs ⊕ hemolytic anemia, drug-induced interstitial nephritis.
resistaNce β-lactamase cleaves the β-lactam ring. Mutations in PBPs.

FAS1_2019_03-Microbiology.indd 187 11/14/19 12:22 PM