Misc Antibiotic Flashcards
Chloramphenicol
Time dependent, bacteriostatic, but can be bactericidal at higher concentrations or against some susceptible organisms
Binds 50S ribosomal subunit of susceptible bacteria, preventing protein synthesis; also has affinity for mitochondrial ribosomes of rapidly proliferating mammalian cells which may result in reversible myelosuppression
Enterococcal and extended spectrum beta lactamase producing gram negative infections;
Broad spectrum antibiotic with good tissue penetration throughout the body including the eyes and CNS
labeled for treatment of pulmonary infections, enteritis, UTIs, infections associated with CDV
in cats, it can be used for treatment of hemotropic mycoplasmosis, chlamydia, ocular infections, and UTIs
Use in extreme caution with pre-existing hematologic disorders or hepatic failure as well as in animals that are pregnant or that are neonates; doses may need to be reduced with hepatic or renal insufficiency
Use lower doses in cats as there is greater risk of complications, especially when used for longer than 14 days (likely due to poor glucuronidation)
AE: GI, myelosuppression, panting aggression, peripheral neuropathy (more common in large breeds), thrombocytopenia in cats
Humans - aplastic anemia
Clofazimine
Antimycobacterial antibiotic used as part of a multi drug therapy for leprosy like or mycobacterium avium related diseases; also effective for other mycobacteria species
Binds to mycobacterial DNA and inhibits growth; slowly bactericidal
ineffective against most other bacteria, fungal, protozoa
anti inflammatory and immunosuppressive effects where mechanism is not understood
Red dye that stains skin, eyes, bodily fluids, excreta; dose limiting gastrointestinal adverse effects, hepatotoxicity, photosensitization
Dapsone
inhibition of synthesis of dihydrofolic acid through competition with para-aminobenzoate for active site of dihydropteroate synthetase; also decreases neutrophil chemotaxis, complement activation, antibody production, lysosomal enzyme synthesis
May be useful for treating protozoal (pneumocystis), brown recluse spider bites, and cutaneous vasculitis, but rarely used due to adverse effects
NOT recommended in cats
AE: hepatotoxicity, methemoglobinemia, anemia, thrombocytopenia, neutropenia, GI effects, neuropathies, cutaneous drug eruptions, photosensitivity possible
Metronidazole
Nitroimidazole, concentration dependent bactericidal
Diffuses across cell membrane of anaerobic bacteria and interacts with DNA to cause strand breaks, resulting in inhibition of protein synthesis and cell death
lipophilic, crosses CSF
activity against most obligate anaerobes; actinomyces frequently resistant as well as clostridia
Antiprotozoal mechanism not completely understood
Use in extreme caution in severely debilitated, pregnant, nursing, or those with hepatic dysfunction
AE: neurologic disorders, lethargy, weakness, neutropenia, hepatotoxicity, hematuria, anorexia, GI; rare cutaneous vasculitis; blood cell genotoxicity in cats possible
significant negative impact on richness of GI microbiome
Methanamine
Urinary antiseptic used for recurrent UTIs, but questionable efficacy
in acidic environment, it is converted to formaldehyde which is a nonspecific antibacterial agent that exerts a bactericidal effect
It can have activity against a variety of bacteria, including both gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus spp) and gram-negative organisms (Escherichia coli, Enterobacter spp, Klebsiella spp, Proteus spp, and Pseudomonas aeruginosa), but may be less effective against those bacteria that produce urease (and increase urine pH). Reportedly, methenamine has activity against fungal UTIs. Hippuric acid or mandelic acid is added primarily to help acidify the urine,
Contraindications - metabolic acidosis, renal insufficiency, servere hepatic impairment, severe dehydration
urine pH must be less than or equal to 6
AE: Gi irritation, dysuria
nitrofurantoin
bacteriostatic urinary antimicrobial; exact mechanism not known, but believed to inhibit various bacterial enzyme systems, including synthesis of DNA, RNA, and proteins, acetylcoA, and energy metabolism and cell wall synthesis
Useful for treatment of bacterial cystitis that is resistant to first line antibiotics
only achieves therapeutic concentrations in urine
Nitrofurantoin has activity against several gram-negative and some gram-positive organisms, including many strains of Escherichia coli, Klebsiella spp, Enterobacter spp, Enterococcus spp, Streptococcus spp, Staphylococcus spp, Enterobacter spp, Citrobacter spp, Salmonella spp, Shigella spp, and Corynebacterium spp. It has little or no activity against most strains of Proteus spp, Serratia spp, or Acinetobacter spp and has no activity against Pseudomonas and Corynebacterium spp.
contraindications with renal impairment
AE: GI disturbances, less common peripheral neuropathy and hepatopathy, pulmonary reactions; chronic active hepatitis, hemolytic anemia, pneumonitis have been described in people
Rifampin
Bactericidal or bacteriostatic antimicrobial depending on organism and concentration
inhibits bacterial, but not mammalian DNA dependent RNA polymerase, thereby suppressing the initiation of chain formation for RNA transcription in susceptible organisms; most active against bacteria undergoing cell division
effective against a variety of mycobacterium and gram positive bacteria; some antifungal when combined with other antifungal agents
Useful adjunct for treating methicillin resistant staph pseudintermedius or as alternative treatment for ehrlichia canis, may be used in combination with doxycycline and gentamicin when treating brucellosis; sometimes combined with other antimycobacterial drugs to treat nontubercular mycobacterial infections
AE: red/orange colored urine, tears, sweat, saliva; GI, lethargy, increased ALT
cats - hepatopathy can be fatal
Vancomycin
inhibits cell wall synthesis and bacterial cell membrane permeability as well as affecting bacterial RNA synthesis
IV antibiotic reserved for life threatening multi drug resistant staphylococcal or enterococcal infections; may be used PO for clostridiodes difficile - oral is not absorbed systemically and only useful for intraluminal enteric infections
generally bactericidal, time dependent, but is bacteriostatic against clostridium, rhodococcus, listeria, corynebacterium, actinomyces
only effective against gram positive bacteria
AE: nephrotoxic, ototoxic; in humans dermatologic reactions and hypersensitivity can occur
IV - thrombophlebitis, hypotension, cardiac arrest if administered too rapidly
Cannot give IM, SC, or IP
