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 (gentamicin) Tetracyclines Inhibit 50S subunit Macrolides Chloramphenicol Clindamycin Linezolid Streptogramins DNA synthesis inhibitors FluoroquinolonesMetronidazole 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) Indications 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 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 diaphragmFemale GUTSS 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 Ineffective in lung infections as drug cannot distinguish between surfactant lipid layer and bacterial membranes, thus is sequestered in surfactant
QUESTIONS 1 of 2 1 2 Previous Next (M1.MC.14.77) A 56-year-old woman with no significant past medical history presents to her primary care physician with a cough. She notes that the cough began two weeks ago and has been worsening. Over the past several days, she has developed low-grade fevers, and the cough has become productive of green mucus. Her physician decides to treat her with a "Z-pack," which is a 5-day course of azithromycin, and orders a chest radiograph, which is shown in Figure A. Which of the following antibiotics has the same target site as azithromycin? QID: 106880 FIGURES: A Type & Select Correct Answer 1 Ciprofloxacin 12% (18/150) 2 Chloramphenicol 61% (91/150) 3 Bacitracin 3% (4/150) 4 Gentamicin 13% (19/150) 5 Vancomycin 9% (14/150) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (M1.MC.13.8) A 21-year-old sexually active man complains of fever, pain during urination, and inflammation and pain in the right knee. A culture of the joint fluid shows a bacteria that does not ferment maltose and has no polysaccharide capsule. The physician orders antibiotic therapy for the patient. The mechanism of action of the medication given blocks cell wall synthesis. Which of the following was given? QID: 101754 Type & Select Correct Answer 1 Chloramphenicol 3% (4/126) 2 Gentamicin 2% (3/126) 3 Ciprofloxacin 9% (11/126) 4 Ceftriaxone 83% (104/126) 5 Trimethoprim 1% (1/126) M 3 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic
All Videos (1) Login to View Community Videos Login to View Community Videos Mechanism of Action of Antibiotics Chris Robinson Microbiology - Antibiotics D 2/14/2015 221 views 5.0 (4)