Updated: 12/7/2018

Antibiotics

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 Overview by Mechanism
 
Antibiotic Grouping by Mechanism
Cell wall synthesis inhibitors
  • Penicillins
  • Cephalosporins
  • Vancomycin
  • Beta-lactamase inhibitors
  • Carbepenems
  • Aztreonam
  • Polymycin
  • Bacitracin
 
Protein synthesis inhibitors  Inhibit 30S subunit
  • Aminoglycosides (gentamycin)
  • Tetracyclines

Inhibit 50S subunit
  • Macrolides
  • Chloramphenicol
  • Clindamycin
  • Linezolid
  • Streptogramins
DNA synthesis inhibitors
  • Fluoroquinolones
    Metronidazole
RNA synthesis inhibitors
  • Rifampin
Mycolic acid synthesis inhibitors
  • Isoniazid
Folic acid synthesis inhibitors
  • Sulfonamides
  • Trimethoprim
 
Classification & Indications
 
Cell Wall Synthesis Inhibitors
Penicillins
(Bactericidal: inhibits bacterial cell wall synthesis via competitive inhibition of the transpeptidase enzyme)
Class Name of Drug(s) Key Indications(s)
Penicillin
  • Penicillin G
  • Aqueous (crystalline) penicillin G
  • Procaine penicillin G
  • Benzathine penicillin G
  • Penicillin V
  • S. pnuemoniae
  • S. pyogenes (group A strep)
  • N. meningitidis
  • T. pallidum
  • L. monocytogenes
  • A. israelii
  • P. multocida
Aminopenicillins
  • Ampicillin
  • Amoxicillin
  • ↑ gram-negative coverage
  • Enterococci (group D strep)
  • All others listed above
Penicillinase-resistant penicillins 
  • Methicillin
  • Nafcillin
  • Oxacillin
  • Cloxacillin
  • Dicloxacillin
  • Penicillinase-producing S. aureus
  • All others listed above
Antipseudomonal penicillins 
  • Carbenicillin
  • Ticarcillin
  • Piperacillin
  • P. aeruginosa
  • Anaerobic bacteria
  • All others listed above
Cephalosporins
(Bactericidal: inhibits bacterial cell wall synthesis via competitive inhibition of the transpeptidase enzyme)
1st generation
  • Cefazolin
  • Cephalexin
  • Gram-positives
  • Some gram-negatives
  • Skin infection prophylaxis
2nd generation
  • Cefoxitin
  • Cefaclor
  • Cefuroxime
  • Gram-positives
  • Improved gram-negative coverage
  • Anaerobes

3rd generation

  • Ceftriaxone
  • Cefotaxime
  • Ceftazidime
  • Serious gram-negative infections
  • Meningitis
  • Pseudomonas
4th generation
  • Cefepime
  • Same coverage as cephalosporins + expanded Pseudomonas coverage + expanded gram-positive coverage
5th generation
  • Ceftaroline
  • Expanded gram-positive and gram-negative coverage, non-suitable coverage of Pseudomonas
Other Cell Wall Inhibitors

Vancomycin                  (bactericidal: inhibits bacterial cell wall synthesis by disrupting peptioglycan cross linking)

  • Vancomycin
  • MRSA
  • Patients with PCN or ceph allergies
  • S aureus
  • S epidermidis
  • C. difficile


Beta-lactamase inhibitors
(beta-lactamse inhibitors that  prevent the degradation of beta-lactam antibiotics)
  • Clavulanic acid
  • Sulbactam
  • Tazobactam
  • Gram-positive
  • S. aureus
  • S. epidermis
  • Gram-negative
  • E. coli
  • Klebsiella
Carbapenems  
(Inhibits bacterial cell wall synthesis)
  • Imipenem (+ cilastatin)
  • Meropenem
  • Doripenem
  • Ertapenem
  • Broadest activity of any antibiotic (does NOT cover MRSA, Mycoplasma, and some Pseudomonas)
Aztreonam 
(inhibits bacterial cell wall synthesis)
  • Aztreonam
  • Gram-negative rods
  • Aerobes
  • Difficult-to-treat hospital-acquired infections
Polymyxins
  • Polymyxin B
  • Polymyxin E
  • Topical gram-negative infections
Bacitracin
  • Bacitracin
  • Topical gram-positive infections
Protein Synthesis Inhibitors
Anti-30S Ribosomal Subunit
Aminoglycosides
(bactericidal)
  • Gentamicin 
  • Neomycin
  • Amikacin
  • Tobramycin 
  • Streptomycin
  • Severe gram-negative infections
  • Aerobes only
  • Can lead to nephrotoxicity and ototoxicity
     
Tetracyclines                    (bacteriostatic)
  • Tetracycline
  • Doxycycline
  • Minocycline
  • Demeclocycline
  • Chlamydia
  • Rickettsia
  • Bacteria without peptidoglycan cell walls
  • Spirochetes
  • V. cholerae
  • H. pylori
Anti-50S Ribosomal Subunit
Macrolides  
  • Erythromycin
  • Azithromycin
  • Clarithromycin
  • Outpatient URI, LRI
  • Atypical pneumonia
  • STDs
  • Gram-positive cocci
Chloramphenicol   
(bacteriostatic)
  • Chloramphenicol
H. influenzae
Bacterial meningitis
Brain abscess
Bacteroides fragilis
Clindamycin  
(bacteriostatic)
  • Clindamycin
Anaerobes above the diaphragm
Female GU
TSS
Linezolid                              (variable)
  • Linezolid
Resistant gram-positives (MRSA, VRE)
Streptogramins
  • Quinupristin
  • Dalfopristin
  • VRE
  • GAS and S. aureus skin infections
  • Note: bacteriocidal when used together
DNA Synthesis Inhibitors
Fluoroquinolones
(Bactericidal: inhibit DNA gyrase enzyme, inhibiting DNA synthesis)
1st generation  
  • Nalidixic acid
  • Gram-negative UTIs
2nd generation 
  • Ciprofloxacin
  • Norfloxacin
  • Enoxacin
  • Ofloxacin
  • Levofloxacin
  • Gram-negative UTIs
  • Gram-negative GI tract
  • Pseudomonas
3rd generation 
  • Gatifloxacin
  • As above + gram-positives
4th generation 
  • Moxifloxacin
  • Gemifloxacin
  • As above + gram-positives + anaerobes
Other DNA Inhibitors
Metronidazole              (bacteridical: metabolic byproducts disrupt DNA)
  • Metronidazole (Flagyl)
  • Bacteria AND protozoa
  • Anaerobes below the diaphragm
  • C. difficile
  • H. pylori
RNA Synthesis Inhibitors
Rifampin   
(bactericidal: inhibits RNA transcription)
  • Rifampin
  • TB
  • Leprosy
  • H. influenzae prophylaxis
  • Antistaphylococcal
Mycolic Acids Synthesis Inhibitors
Isoniazid  
  • Isoniazid
  • TB
  • Latent TB
Folic Acid Synthesis Inhibitors
Sulfonamides  
  • Sulfamethoxazole (SMX)
  • Sulfisoxazole
  • Sulfadiazine
  • Respiratory (S. pneumoniae, H. influenzae)
  • GI (enterics)
  • UTIs
  • PCP and T. gondii
Trimethoprim
  • Trimethoprim
  • See Sulfonamides
Pyrimethamine 
  • Pyrimethamine
  • Malaria
  • T. gondii
Miscellaneous   
Drugs Mechanism of Action Indications and Side Effects
Pyrazinamide
  • Uncertain mechanism: potentially accumulates in cells dsirupting membrane potential and fatty acid synthesis
  • Part of RIPE therapy for TB
  • Can cause hyperuricemia and hepatoxicity
Ethambutol
  • Inhibits arabinosyltransferase (inhibiting production of mycobacterium cell wall)
  • Part of RIPE therapy for TB and used for M. avium-intracellulare
  • Can cause optic neuropathy (red-green color blindness)
Daptomycin
  • Lipopeptide that disrupts cell membrane
  • Multi-resistant gram-positives such as MRSA and VRE
  • Can cause myopathy (elevated CK and rhabdomyolysis
 

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Questions (1)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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