Antibiotic Classes and Activity
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Bacteria by classification Gram Postive Gram Negative Anaerobes Atypical Other
Cocci: Staphylcocci (clusters), S. pneumoniae (pairs), Group and viridans streptococci (chains), Enterococcus sp (pairs and chains);     Bacilli: Bacillus sp, Corynebacterium sp, Listeria monocytogenes, Nocardia sp Cocci: Moraxella catarrhalis, Neisseria gonorrhoeae, Neisseria meningitidis, Haemophilus influenzae                         Bacilli: E. coli, Enterobacter sp, Citrobacter, Klebsiella sp, Proteus sp, Serratia, Salmonella, Shigella, Acinetobacter, Helicobacter, Pseudomonas aeruginosa Above diaphragm: Peptococcus sp, Peptostreptoccus sp, Prevotella, Veillonella, Actinomyces                         Below diaphragm: Clostridium perfringens, tetani, & difficile, Bacteroides fragilis, disastonis, ovatus, & thetaiotamicron, Fusobacterium Legionella pneumophilia, Mycoplasma pneumoniae or hominis, Chlamydia pneumoniae or trachomatis Treponema pallidium (syphillis), Borrelia burgdorferi (Lyme)
Bacteria by infection site Mouth Skin/Soft Tissue Bone and Joint Abdomen Urinary Tract Upper Respiratory Lower Respiratory Meningitis
Peptococcus, Peptostreptococcus, Actinomyces S. aureus, S. pyogenes, S. epidermidis, Pasteurella S. aureus, S. epidermidis, Steptococci, N. gonorrhoeae, Gram-negative rods E. coli, Proteus, Klebsiella, Enterococcus, Bacteroides sp E. coli, Proteus, Klebsiella, Enterococcus, Staph saprophyticus   Community: S. pneumoniae, H. influenzae, K. pneumoniae, Legionella pneumophilia, Mycoplasma, Chlamydia    Hospital: K. pneumoniae, P. aeruginosa, Enterobacter sp, Serratia sp, S. aureus S. pneumoniae, N. meningitis, H. influenzae, Group B streptococcus, E. coli, Listeria
Common Pathogens by Disease
Activity
Antibiotic Class Drugs in Class Mechanism of Action Gram Positive Gram Negative Anaerobes Atypical Other
Penicillins Penicillin G, Penicillin VK Inhibits cell wall synthesis by binding to penicillin-binding proteins (PBP) which are located in bacterial cell walls  Are bactericidal (except against enterococcus). Penicillin-susceptible S. Aureus & S. Pneumoniae, Group streptococci, viridans, streptococci, enterococcus Neisseria sp. Above diaphragm sp (see above), Clostridium sp None Treponema pallidum (syphilis)
Penicillinase-Resistant Penicillins Nafcillin, Oxacillin, Methicillin Same as above, except these were designed to overcome the penicillinase enzyme of S. aureus which inactivated natural penicillins Methicillin-susceptable S. aureus, Group streptococci, Viridans streptococci None None None None
Aminopenicillins Ampicillin, Amoxicillin Same as above.  Developed to have increased activity against gram-negative aerobes Penicillin-susceptible S. Aureus, Group streptococci, viridans streptococci, Enterococcus sp, Listeria monocytogenes Proteus mirabilis, Salmonella, Shigella, some E. coli, some H. influenzae None None None
Carboxypenicillins Carbenicillin, Ticarcillin Same as above.  Have increased activity against resistant gram-negative aerobes than Aminopenicillins Marginal activity Proteus mirabilis, Salmonella, Shigella, some E. coli, some H. influenzae, Enterobacter sp, Pseudomonas aeruginosa None None None
Ureidopenicillins Piperacillin, Azlocillin Same as above.  Have greater activity against resistant gram-negative aerobes than Carboxypenicillins Viridans strep., Group strep, some Enterococcus Proteus mirabilis, Salmonella, Shigella, E. coli, some H. influenzae, Enterobacter sp, Pseudomonas aeruginosa, Serratia marcescens, some Klebsiella sp Fairly good activity    
B-Lactamase Inhibitor Combinations Unasyn, Augmentin, Timentin, Zosyn Same as above.  Have greater activity against B-lactamase producing organisms S. aureus H. influenzae, E. coli, Proteus sp, Klebsiella sp, Neisseria gonorrhoeae, Moraxella catarrhalis Bacteroides sp    
First generation cephalosporins Duricef, Kefzol, Keflex, Cephalothin, Velosef Inhibits cell wall synthesis by binding to penicillin-binding proteins (PBP) which are located in bacterial cell walls  Best activity of cephalosporins against gram-positive/limited against gram-negative.  Are bactericidal. Methicillin-susceptable S. aureus, Penicillin-susceptable S. pneumoniae, Group streptococci, Viridans streptococci E. coli, K. pneumoniae, P. mirabilis      
Second generation cephalosporins Ceclor, Mandol, Zefazone, Precef, Cefotan, Mefoxin, Cefzil, Ceftin, Zinacef, Lorabid Same as above.  Slightly less active against gram-positive, but more active against gram-negative and some anaerobic activity.  Are bactericidal. Methicillin-susceptable S. aureus, Penicillin-susceptable S. pneumoniae, Group streptococci, Viridans streptococci E. coli, K. pneumoniae, P. mirabilis, H. influenzae, M. catarrhalis, Neisseria sp Bacteroides fragilis, Bacteroides fragilis group - only with cefotan, mefoxin, & zefazone    
Third generation cephalosporins Omnicef, Suprax, Claforan, Vantin, Cefizox, Rocephin, Fortaz Same as above. Less active than second generation against gram-positive, but more active against gram-negative. Rocephin & Claforan have best activity against gram-positive (including pen-resistant S. pneumoniae).  Are bactericidal.   E. coli, K. pneumoniae, P. mirabilis, H. influenzae, M. catarrhalis, Neisseria gonorrhoeae (including B-lactamase producing), N. meningitdis, Citrobacter sp, Enterobacter sp, Acineobacter sp, Morganella morganii, Serratia marcescens, Providencia, Pseudomonas aeruginosa (Fortaz)      
Fourth generation cephalosporins Maxipime Same as above.  Extended spectum of activity.  Are bactericidal. Similar to Rochepin (see above) Similar to Fortaz (see above)      
Carbapenems Merrem, Primaxin, Invanz Inhibits cell wall synthesis by binding to penicillin-binding proteins (PBP) which are located in bacterial cell walls.  Are bactericidal. Good coverage; does not cover MRSA, VRE, coagulase-negative staph, or Nocardia Good coverage; does not cover S. maltophilia Good coverage; does not cover C. difficile None None
Monobactams Azactam Same as above, except these bind preferentially to PBP-3 of gram negative aerobes.  Are bactericidal. Little to no activity E. coli, K. pneumoniae, P., mirabilis, S. marcescens, H. influenzae, M. catarrhalis, Enterobacter, Citrobacter, Providencia, Morganella, Salmonella, Shigella, Pseudomonas aeruginosa Little to no activity None None
Fluoroquinalones Olders agents: Noroxin, Cipro                           Newer agents: Levaquin, Tequin, Avelox, Trovan, Factive Inhibit bacterial topoisomerases which are necessary for DNA synthesis.  Primary target for gram-positive bacteria is DNA gyrase, and primary target for gram-negative bacteria is Topoisomerase IV.  Concentration-dependant bactericidal activity Older agents have poor activity.  Newer agents cover MSSA, Strep pneumoniae (including PRSP), group and viridans steptococci (limited activity), and Enterococci sp (limited activity) All have excellent activity (cipro=levo>gati>moxi). Cover E. coli, Klebsiella sp, Enterobacter sp, Proteus sp, Salmonella, Shigella, Serratia marcescens, and other enterobacteriaceae; H. influenzae, M. catarrhalis, Neisseria sp, Pseudomonas aeruginosa (significant resistance - cipro & levaquin have best activity) Only Trovan has activity against Bacteroides sp All have excellent activity against atypical including: Legionella pneumonia (drugs of choice), Chlamydia sp, Mycoplasma sp, Ureoplasma urealyticum Mycobacterium tuberculosis, Bacillus anthracis
Macrolides Erythromycin, Zithromax, Biaxin Inhibits protein synthesis by reversibly binding to the 50S ribosomal subunit.  Suppression of RNA-dependent protein synthesis.  Bacteriostatic activity (biaxin>e-mycin>zithro)    MSSA, strep pneumoniae (only PSSP - resistance developing), group and viridans steptococci, bacillus sp, corynebacterium sp (zithro>biaxin>e-mycin)    H. influenzae (not e-mycin), M. catarrhalis, Neisseria sp.  Do not have any activity against any enterobacteriaceae Activity against Peptococcus sp, Peptosteptococcus sp, Prevotella, Veillonella, Actinomyces All have excellent activity against atypical including: Legionella pneumonia (drugs of choice), Chlamydia sp, Mycoplasma sp, Ureoplasma urealyticum Mycobacterium avium complex (MAC - only A and C), Treponema pallidum, Campylobacter, Borrelia, Bordetella, Brucella, Pasteurella
Aminoglycosides Gentamicin, Tobramycin, Amikacin, Kantrex, Neomycin, Steptomycin Irreversibly bind to 30S ribosomes, which disrupt the initiation of protein synthesis, decreases overall protein synthesis, and produces misreading of mRNA.  Are bactericidal most S. aureus and coagulase-negative staph, viridans steptococci, enterococcus sp All but steptomycin: E. coli, K. pneumoniae, Proteus sp, Acinetobacter, Citrobacter, Enterobacter sp, Morganella, Providencia, Serratia, Salmonella, Shigella, Pseudomonas aeruginosa (amik>tobra>gent) None Coverage with amikacin and streptomycin Mycobacterium tuberculosis - streptomycin
Vancomycin Vancomycin Binds to D-alanyl-D-alanine portion of cell wall precursors to inhibit synthesis and assembly of the second stage of peptidoglycan polymers.  Are bactericidal (except for Enterococcus) MSSA, MRSA, coagulase-negative staph, Strept pneumoniae (including PRSP), Viridans streptococcus, Group streptococcus, Enterococcus sp, Corynebacterium, Bacillus, Listeria None Actinomyces, Clostridium sp (including C. difficile), Peptococcus, Peptostreptococcus None None
Streptogramins Synercid Each agent (quinupristin/dalfopristin) acts on 50S ribosomal subunits to inhiit early and late stages of protein synthesis.  It is bacteriostatic MSSA, MRSA, coagulase-negative staph, Strept pneumoniae (including PRSP), Viridans streptococcus, Group streptococcus, Enterococcus faecium (only), Corynebacterium, Bacillus, Listeria Limited activity against Neisseria sp, and Moraxella Actinomyces, Clostridium sp (except C. difficile), Peptococcus, Peptostreptococcus Mycoplasma, Legionella None
Oxazolidinones Zyvox Binds to the 50S ribosomal subunit near to surface interface of 30S subunit, which causes inhibition of 70S initiation complex which inhibts protein synthesis.  It is bacteriostatic MSSA, MRSA, VRSA, coagulase-negative staph, strep pneumoniae (including PRSP), viridans streptococcus, Group streptococcus, Enterococcus faecium and faecalis (including VRE), Bacillus, Listeria Relatively inactive Clostridium sp (except C. difficile), Peptostreptococcus, P. acnes Mycoplasma, Chlamydia, Legionella None
Lincosamide Clindamycin, Lincocin Binds to 50S ribosomal subunit to inhibit protein synthesis.  Typically is bacteriostatic. MSSA, Strep pneumoniae (PSSP only), Group and viridans streptococci None Peptostreptococcus, some Bacteroides sp, Actinomyces, Prevotella sp, Propionibacterium, Fusobacterium, Clostridium sp (not C. difficile) None Pneumocystis carinii, Toxoplasmosis gondii, Malaria
Metronidazole Flagyl Prodrug which is activated by a reductive process.  It have selective toxicity against anaerobic and microaerophilic bacteria due to the presence of ferredoxins within these bacteria.  It it bactericidal. None None Bacteria: Bacteroides sp (all), Fusobacterium, Prevotella sp, Clostridium sp (all), Helicobacter pylori; Protozoa: Trichomonas vaginalis, Entamoeba histolytica, Giardia lamblia, Gardnerella vaginalis None None
Glycylcyclines Tygacil Reversibly binds to the A site of the 30S ribosomal subunit.  It is bacteriostatic, but demonstrates bactericidal activity against certain pathogens Enterococcus faecalis, Enterococcus faecium (both VRE and non-VRE), Staph aureus (both MRSA and MSSA), Streptococcus pneumoniae (both PCN susceptible and PCN resistant) Acinetobacter baumannii, Enterobacter cloacae, Enterobacteriaceae sp, E. coli (both ESBL and non-ESBL), H. influenzae (both BL positive and negative), K. pneumoniae (both ESBL and non-ESBL), P. aueruginosa, S. marcescens Fusobacterium sp, Prevotella sp, Peptostreptococcus sp, C. difficile None None
Cyclic Lipopeptide Cubicin Binds to components of the cell membrane of susceptible organisms and causes rapid depolarization, inhibiting intracellular synthesis of DNA, RNA, and protein.  It is bactericidal in a concentration dependent manner MSSA, MRSA, coagulase negative staphylococci, oxacillin-resistant S. aureus & S. epidermidis, PCN susp & resistant S. pneumoniae, viridans steptococci, streptococcus sp, VSE, VRE None None None None