ANTIMICROBIAL SUSCEPTIBILITY PROFILES

Good = organisms susceptible to low concentrations
Moderate = organisms susceptible but to high therapeutic concentrations
Resistant = organisms either completely resistance or with a high incidence of acquired resistance.

Penicillins
Penicillin G (Benzyl Penicillin G)
Good Aerobic: all beta-hemolytic Streptococci; B. anthracis; most corynebacteria; E. rhusiopathiae, most L. monocytogenes.
Anaerobic: Clostridium, Fusobacterium, and some Bacteroides
Moderate Actinobacillus, Borrelia, Brucella, Haemophilus, Leptospira, Moraxella, Pasteurella, Proteus, T. equigenitalis, Treponema sp.
Resistant Constitutive: Enterobacteriaceae (except a few Proteus), Bacteroides fragilis, Bordetella, most Campylobacter, Nocardia.
Acquired: Many strains of S. aureus, S. intermedius
Ampicillin, Amoxicillin (Broad Spectrum Aminobenzyl Penicillins)
Good as for benzyl penicillin but also Borrelia,Leptospira,Moraxella
Moderate as for benzyl penicillin and Campylobacter, R. equi, and enterococci
Resistant Constitutive: Bacteroides fragilis, B. bronchiseptica, Citrobacter, Enterobacter, Klebsiella, other Proteus, P. aeruginosa, Serratia, Y. enterocolitica. Acquired: Actinobacillus, E. coli, P. mirabilis, and Salmonella, and widespread resistant by Enterobacteriaceae (though they are considered part of the general spectrum).
Carbenicillin, Ticarcillin (Carboxypenicillins)
Good gram negative activity especially against P. aeruginosa, and Proteus. (Temocillin is beta-lactamase resistant member of class but not available here).
Methcillin, Oxacillin, Cloxacillin, Nafcillin (Penicillinase-resistant Penicillins)
GoodPenicillinase producing Staphylococci.
ModerateOther Gram postives (that are MORE susceptible to Penicillin G and Ampicillin)
ResistantMost Gram (-)
Mecillinam (Amidinopenicillins)
Good Citrobacter, Enterobacter, E. coli, K. pneumoniae, Proteus, Yersinia.
ResistantLittle gram positive activity.
Piperacillin (Acylaminopenicillins - Ureidopenicillins)
Good Noted for increase activity against gram-negative bacteria compared to carbenicillin or ampicillin especially Klebsiella, and P. aeruginosa.
ResistantThese are susceptible to beta-lactamases so resistance among Enterobacteriaceae is unpredicatable and most Enterobacter and Serratia are resistant.
Potentiated Penicillin Combinations
Amoxicillin - Clavulanic Acid (Clavamox, Augmentin)
Good S. aureus, beta hemolytic Streptococci. Actinobacillus, Bordetella, Haemophilus, Pasteurella, Enterobacteriaceae are usually susceptible; all anaerobes including B. fragilis (penicillinase production varies).
Variable some E. coli, and Klebsiella
Resistant Citrobacter, Enterobacter, P. aeruginosa, Serratia, methicillin resistant S. aureus
Ampicillin - Sulbactam (Unasyn)
activity is slightly broader (a few more isolates) than Clavulanic Acid - Amoxicillin but the overall activity is somewhat less (lower potency, slower kills etc.)
Ticarcillin - Clavulanic acid (Timentin)
Advantage (over Clavamox) is greater activity of ticarcillin against Enterobacter and P. aeruginosa.
Good Ticarcillin resistant Enterobacteriaceae, S. aureus,
Anaerobes including B. fragilis, and P. aeruginosa.
Moderate activity against many Enterobacteriaceae is at the high end of the sensitive or in the moderately susceptible MIC range.
Resistant mostly by induction of non-bound beta-lactamases in Gram negatives such as Enterobacter, P. aeruginosa, and Serratia.
Carbapenams
Imepanam
Good most gram-positive cocci (including enterococci), some Mycobacterium sp.,
Anaerobes including B. fragilis, Most activity of beta-lactam antibiotics against gram-negative bacteria including beta-lactamase producing fastidious organisms, Enterobacteriaceae and most P. aeruginosa.
Resistant Pseudomonas cepacia, P. maltophila, some S. faecium, some methicillin-resistant S. aureus.
Monobactams
Aztreonam
Good almost all gram-negative aerobic bacteria, particularly fastidious organisms (Haemophilus, etc.) and Enterobacteriaceae. Susceptibility of P. aeruginosa is variable.
ResistantGram-positive bacteria, anaerobic bacteria, Pseudomonas, Citrobacter, and Enterobacter are often resistant.
Cephalosporins and Cephamycins
Cefadroxil, Cephalexin (1st Generation Oral)
Good Aerobic: Many gram positive including S. aureus, S. intermedius, Streptococci (not enterococci), Actinomyces, Bacillus, Corynebacteria, E. rhusiopathiae, most L. monocytogenes, B. avium, Haemophilus, Pasteurella.
Anaerobic: some Bacteroides, most Clostridium, most Fusobacterium.
Variable due to acquired resistance by E. coli, Klebsiella, Proteus, Salmonella Cefachlor and Cefpodoxime is most active against this group. Cefpodoxime is better absorbed than Cefachlor
Moderate Actinobacillus, Brucella, some Bacteroides
Resistant Acenetobacter, B. fragilis, B. bronchiseptica, Campylobacter, Citrobacter, Enterobacter, Nocardia, S. faecalis (enterococci), P. aeruginosa, R. equi, Serratia, Yersinia
Cefachlor (2nd Generation Oral)
Good E. coli, Klebsiella, Proteus, Salmonella (though there is acquired resistance among these)
Moderate Aerobic: Many gram positive including S. aureus, S. intermedius, Streptococci (not enterococci), Actinomyces, Bacillus, corynebacteria, E. rhusiopathiae, most L. monocytogenes, B. avium, Haemophilus, Pasteurella.
Anaerobic: some Bacteroides, most Clostridium, most Fusobacterium (The list that was GOOD for 1st Generation Oral)
Cefpodoxime (3rd Generation Oral)
Better absorbed than Cefachlor but similar activity (expect better results clinically)
Cephalothin, Cephazolin, Cefapirin, Cephradine (1st Generation Parenteral)
Share the general characteristics of orally administered 1st generation cephalosporins. They tend to have good activity against Gram positive organisms and variable to poor activity against gram negatives. May be more active against bacteria in VARIABLE and MODERATE categories because they reach better plasma/tissue concentrations.
Cefamandole (1st or 2nd generation), Cefmenoxime (2nd generation), Cefotaxime, Ceftriaxone, Ceftiofur, Cefuroxime (3rd Generation)
These tend to have better activity against Gram negative bacteria and lesser activity against gram positive bacteria than the Group I parenterals. The 3rd generation drugs tend to have longer half-lives and can be dosed less frequently than Group I parenterals, but this can vary by species (don't count on it).
Good Gram (+) Streptococci(not enterococci), moderate activity against S. aureus (cefamandole more active). Good against many other gram-positive (penicillin G sensitive). Gram (- ) E. coli, Klebsiella, and Salmonella, most Proteus to cefotaxime group (cefotriaxone, ceftiofur). Actinobacillus, Haemophilus, Pasteurella are all susceptible (including penicillinase producing strains). Anaerobes Clostridium, and Fusobacterium susceptible, Bacteroides, resistant.
Variable acquired resistance in Enterobacteriaceae
Moderate Citrobacter, Enterobacter, P. aeruginosa, Serratia susceptible (only) to cefotaxime group.
Resistant Bordetella, some Enterobacter, and Serratia, some P. aeruginosa (all for cefuroxime, cefamandole, some for cefotaxime group), enterococci, methicillin-resistant S. aureus.
Cefoperazone, Ceftazidime (3rd Generation Parenteral)
These have the best gram negative activity of the cephalosporins. Both have excellent activity against P. aeruginosa. Otherwise similar to Group II Parenteral Cefotaxime group above.
Cefoxitin, Cefotetan (2nd Generation Parenteral), Moxalactam (3rd Generation Parenteral)
cefoxitin Resistant to most bacterial beta-lactamases, gram negative activity is less compared to cefotaxime group above, greater than Group I parenterals above. Gram positive activity is less than Group I parenterals. Good activity against Bacteroides fragilis.
cefotetan NO LONGER MARKETED IN US. greatest activity against gram negatives of this group but P. aeruginosa is resistant. Small portion of Bacteroides fragilis are resistant.
moxalactam similar to cefotaxime, ceftiofur above but better activity against B. fragilis. Not particularly active against S. aureus. Some Pseudomonas aeruginosa, are resistant. Noted for activity against anaerobic organisms.
Aminoglycosides
Streptomycin
Goodmycobacteria, some mycoplasma, some gram-negative rods including Brucella, and some S. aureus. (least active aminoglycoside except vs. mycobacteria). Leptospira, F. tularensis, and Y. pestis, and most Campylobacter fetus subsp venerealis.
Resistantwidespread acquired resistance among Gram (-) organisms.
Neomycin (Dihydrostreptamine aminoglycosides)
Good Gram (-) pathogens, more active than streptomycin, less active than gentamicin, tobramycin and amikacin. some S. aureus.
Resistant widespread acquired resistance among Gram (-) organisms.
Gentamicin, Kanamycin, Tobramycin, Apramycin, Netilmycin, Sisomici (Kanamycin Group)
Good , Serratia, Yersinia, Brucella, Campylobacter, Haemophilus, and Pasteurella most P. aeruginosa. Gram (+) S. aureus is usually susceptible though acquired resistance is becoming more common. Prototheca susceptible.
Resistant Constitutive: many gram-positive aerobes, all anaerobes, some Pseudomonas Acquired:Enterobacteriaceae including Enterobacter, E. coli, Klebsiella, Proteus and S. aureus
Amikacin
Slightly less active and slightly less toxic than gentamicin but resistant to most bacterial enzymes that inactivate other aminoglycosides.
Apramycin
Appears to have similar activity to other aminoglycosides though literature studies of spectrum are lacking. Used for E. coli, Salmonella, Treponema in piglets and calves.
Spectinomycin
Similar activity to other aminoglycosides. Because of resistance in the population, activity against gram negative aerobes is probably less predictable than gentamicin. (in a study of Pasteurella isolates, about half were classified as resistant).
Tobramycin
Active against more isolates of P. aeruginosa than is gentamicin (2/3 of Gentamicin resistant organisms are susceptible).
Polymyxins, Glycopeptides, Mupirocin, Bacitracin
Polymixin B, Colistin
Good Good activity against many species of Gram (-) bacteria
Resistant No activity against Proteus, Serratia, Providencia, Gram (+) organisms. Acquired resistance rare except P. aeruginosa.
Vancomycin (Glycopeptides)
Good bactericidal to most Gram (+) aerobic cocci and bacilli
Resistant most Gram (-) bacilli are resistant.
Mupirocin
Good Staphylococci and Streptococci
Resistant most other Gram (+) and Gram (-) bacteria.
Bacitracin
Good Gram (+) bacteria. includes C. perfringens (used in pigs and poultry)
Resistant Gram (-) bacteria
Lincosamides, Macrolides, and Plueromutilins
Lincomicin, Clindamycin (Lincosamides)
Good Gram (+) aerobes: Bacillus, Corynebacterium sp., E. rhusiopathiae, staphylococci, Streptococci (but not enterococci). Gram (-) bacteria: Campylobacter. Anaerobes including Actinomyces, Bacteroides (including B. fragilis) C. perfringens (but not all Clostridium), Fusobacterium, anaerobic cocci and T. hyodysenteriae.
Resistant all aerobic Gram (-) rods, Nocardia, Mycobacterium sp.
Erythromycin, Tylosin, Spiramycin, Tilmicosin, Tulathromycin, Azithromycin, Clarithromycin (Macrolides)
Erythromycin
Good Gram (+) aerobes: Bacillus, Corynebacterium sp., E. rhusiopathiae, Listeria sp., staphylococci, Streptococci. Gram (-) aerobes:Actinobacillus, Brucella, Campylobacter, Leptospira, Anaerobic bacteria: Actinomyces, Bacteroides(except B. fragilis), Clostridium, some Fusobacterium, anaerobic cocci.
Moderate Enterococci, some Bordetella, Haemophilus, Legionella, Ehrlichia, Pasteurella
Resistant Enterobacteriaceae, Pseudomonas, Nocardia, Mycoplasma, Chlamydia psittaci, Mycobacterium sp. other than M. kansasii
Tylosin Similar spectrum to Erythromycin. Less active against most bacteria except T. hyodysenteriae, but more active against most Mycoplasma.
Spiramycin Similar spectrum to Erythromycin but less active. Less active against Mycoplasma as tylosin or tiamulin.
Tilmicosin, Tulathromycin, Azithromycin, Clarithromycin New to veterinary medicine. Restricted list of species/disorders evaluated. Similar spectrum to Erythromycin but higher portion of all bacteria probably susceptible. More active against Mycoplasma than other members of this class.
Tiamulin (Pleuromutilins)
Similar spectrum to that of tylosin but much greater activity. Active against only a few Gram (-) bacteria and inactive against Enterobacteriaceae. Subinhibitory concentrations are thought to reduce adhesiveness of E. coli.
Chloramphenicol(s)
Chloramphenicol, Florfenicol
Good Gram (+) aerobic bacteria: A. pyogenes, B. anthracis, Corynebacterium sp., E. rhusiopathiae, L. monocytogenes, Staphylococcus sp., Streptococcus sp. Gram (-) aerobic bacteria: Actinobacillus, B. bronchiseptica, B. canis, Enterobacteriaceae including many E. coli, Klebsiella, Proteus, Salmonella, Haemophilus, Moraxella, Pasteurella All anaerobes.
Moderate Leptospira, R. equi
Resistant Mycobacterium sp., Nocardia, Acquired resistance by Enterobacteriaceae described above.
Tetracyclines
Chlortetracycline, Oxytetracycline, Tetracycline, Doxycycline, Minocycline
Differences between the tetracyclines is a matter of solubility (hence pharmacokinetics, tissue penetration, etc.). Subtle differences in resistance patterns may exist because drug "exclusion," a primary form of tetracycline resistance, may be overcome by increased lipid solubility (old tetracyclines < doxycycline < minocycline)
Good Gram (+) aerobes: Bacillus, Corynebacterium sp., E. rhusiopathiae, L. monocytogenes, Streptococci. Gram (-) bacteria: Actinobacillus, Bordetella ,Brucella, F. tularensis, Haemophilus, P. multocida, Yersinia, Campylobacter fetus, Borrelia, Leptospira Anaerobes: Actinomyces, Fusobacterium also: Mycoplasma, Chlamydia sp. (including C. psittaci), Rickettsia sp., (inluding C. burnetii, Ehrlichia sp., and protozoa (Theileria, Eperythrozoon, and Anaplasma).
Resistant Constitutive: some Mycobacterium sp., P. vulgaris, P. aeruginosa, Serratia Acquired: staphylococci, enterococci, Enterobacteriaceae. Anaerobes such as Bacteroides, and Clostridium, some Mycoplasma (M. bovis, M. hyopneumoniae are resistant)
Sulfonamides
Sulfathiazole, Sulfamethazine, Sulfamerazine, Sulfadiazine, etc.
Good Actinomyces, Bacillus, Brucella, ,E. rhusiopathiae, L. monocytogenes, Streptococcus sp., Chlamydia sp., coccidia, Pneumocystis carinii, Cryptosporidium sp.
Moderate (or variable due to acquired resistance): Gram (+) aerobes: staphylococci, enterococci. Gram (-) aerobes: Enterobacteriaceae including Enterobacter, E. coli, Klebsiella, Proteus, Actinobacillus, Haemophilus, Pasteurella, Pseudomonas, Anaerobes: Actinomyces, Bacteroides, Fusobacterium
Resistant Clostridium, and anaerobic cocci. Mycobacterium sp., Mycoplasma, Rickettsia sp., P. aeruginosa, and spirochetes.
Sulfadiazine-Trimethoprim, Sulfamethoxasole-Trimethoprim, Sulfonamide-Ormetoprim (Sulfonamide THF-Reducatase Inibitor combinations)
Good Gram (+) Aerobes: S. aureus, Streptococci, Actinomyces, Corynebacterium sp, E. rhusiopathiae, L. monocytogenes. Gram (-) aerobes: Actinobacillus, Bordetella, Brucella, Enterobacteriaceae such as E. coli, Klebsiella, Proteus, Salmonella, Yersinia, Haemophilus, Pasteurella,
Anaerobes: Actinomyces, Bacteroides, Fusobacterium, some Clostridium, Chlamydia sp.
Moderatesome Mycobacterium sp., some Nocardia
ResistantRickettsia, Leptospira, P. aeruginosa, Mycoplasma
Sulfonamide - Pyrimethamine
better activity than trimethoprim against coccidia, Toxoplasma lesser antibacterial activity than trimethoprim
Fluoroquinolones
Enrofloxacin, Norfloxacin, Ciprofloxacin, Orbifloxacin
Good (1) Gram (-) aerobes including Enterobacteriaceae (E. coli, Klebsiella, Proteus, Salmonella, Actinobacillus, Brucella, Haemophilus, Leptospira, Moraxella, Pasteurella, P. aeruginosa. Mycoplasma, Rickettsia, C. burnetii, Ehrlichia, Gram (+) aerobes are not as susceptible (most S. aureus in moderate range)
Moderate (or variable) Streptococci. S. agalactiae, S. dysgalactiae, S. suis, S. zooepidemicus, R. equi , Mycobacteria
Resistant Anaerobic bacteria. P. maltophila
Nitrofurans
Nitrofurazone, Nitrofurantoin, Furazolidone
n.b. Susceptibility testing of these compounds is done at a high concentrations (because the dominant therapeutic use of these compounds is for the treatment of urinary tract infections). Very little is known about the real activity of this group against systemic infections.
Good Gram (+) Aerobes: S. aureus, Streptococci, many corynebacteria. Gram (-) aerobes E. coli, and Salmonella. Some activity against Mycoplasma, coccidia, giardia, and trypanosomes.
Resistant Gram (-) most Klebsiella, Proteus, all P. aeruginosa.
Nitroimidazoles
Metronidazole
Good Bactericidal to most Gram (-) and Gram (+) anaerobic bacteria. Protozoa, Giardia, T. hyodysenteriae
Resistant All aerobic bacteria.
Rifamycins
Rifampin
Good wide spectrum. most bacteria, Chlamydia, Rickettsia, some protozoa, some fungi, and poxviruses. Particularly active against Gram (+) bacteria and Mycobacteria.
Resistant high-level resistance develops in almost any bacterial population so rapidly that the drug, used alone, is of little value in infectious disease therapy.
Arsenic containing antimicrobials
Arsanilic Acid, Sodium Arsanilate, 3-Nitro-4-hydroxyphenylarsanilic acid (Arsenicals)
There is little recent evidence available to evaluate the activity of arsenicals. They are used to promote growth in pigs and poultry and to treat swine dysentery (low efficacy for the latter). They are also used in a non-specific manner to control chronic diarrhea of unknown etiology in swine.
Miscellaneous
Carbadox
Good Clostridium, T. hyodysenteriae, and against facultative aerobic bacteria under anaerobic conditions.
Resistant Plasmid mediated resistance has been described but its significance is not known.
Isoniazid
Good M. tuberculosis, M. bovis, Actinomyces bovis
Resistant M. aviumintracellulare, R. equi, C. pseudotuberculosis, S. zooepidemicus
Methenamine
Good ALL urinary tract pathogens if sufficient concentrations are produced.
Resistant most urease-producing bacteria (urine too alkaline for action).
Novobiocin
Good S. aureus
Moderate Streptococci, fastidious Gram (-) bacteria
Resistant Enterobacteriaceae and Pseudomonas
Virginiamycin
Good Gram (+) aerobic and anaerobic bacteria. Gram (-) aerobes: Leptospira, T. hyodysenteriae, and Haemophilus, Mycoplasma, Toxoplasma
Resistant Most Gram (-) bacteria
Antifungal drugs
Topical Antifungal Drugs
Natamycin
Good wide range of filamentous and dimorphic fungi, yeasts. Including Taenea, Candida, Fusarium, Aspergillus
Nystatin
Good Candida, Pityrosporum, Cryptococcus, dermatophytes, some filamentous fungi and some dimorphic fungi, Prototheca
Resistant several Candida other than C. albicans
Clotrimazole, Miconazole (Azole antibiotics)
Good wide range of filamentous fungi, including Aspergillus and dermatophytes, yeasts and dimorphic fungi. Malassezia
Systemic antifungal
Griseofulvin
Good all dermatophytes
Resistant all other hyphal fungi, yeasts, dimorphic fungi and bacteria
Amphotericin B
Good in decreasing order of susceptibility: Blastomyces dermatitidis, Histoplasma capsulatum, Cryptococcus neoformans, Candida, Sporothrix schenckii, Coccidioides immitis, Aspergillus. many yeasts are also susceptible as is Prototheca.
Resistant some resistant Candida, C. immitis, Mucor, Aspergillus
Flucytosine
Good C. neoformans, Candida, Torulopsis, Cladosporium a few Aspergillus.
Resistant Dermatophytes, filamentous fungi, and dimorphic fungi. Most yeast isolates from bovine mastitis are resistant.
Azole antifungal drugs (Ketoconazole, Itraconazole, Fluconazole)
Ketoconazole
Good wide range of filamentous fungi (including dermatophytes), yeasts, dimorphic fungi. C. albicans, Malessezia canis, some Aspergillus.
Resistant some acquired resistance reported, some Aspergillus. Prototheca are resistant in vitro but respond in vivo. C. tropicalis
Itraconazole
Good in addition to organisms susceptible to ketoconazole: dimorphic fungi, Cryptococcus, Sporothrix, Alternaria, most Aspergillus, C. tropicalis
Variable Candida, dermatophytes.
Fluconazole
Good probably similar to ketoconazole. Still being evaluated.
Iodides
Iodides have been used for years to treat mycotic infections. Efficacy has never clearly been documented. Often included with other antifungal therapies.