-
sulfamethoxazole
- false substrate competitively inhibits binding of PABA to DHPS enzyme
- bacteriostatic
- typically oral, can be given IV
- well distributed, CNS and CSF
- excretion: liver metabolism, excreted by kidneys (dose reduction in renal failure)
- broad spectrum - many G+ and G-, also targets parasites, NOT Ricksettsia
- resistance: widespread, cross resistance to all sulfas is typical
- adverse effects: gi distress, common rash, bone marrow and liver toxicity not uncommon, hemolytic anemia with G6PDD, kernicterus (in infacts, sulfa competes for bilirubin binding sites on albumin and increases levels of unconjugated bilirubin = CNS toxicity), Stevens-Johnson syndrome (hypersensitivity with mucosal sloughing, skin eruptions
- use: not typically used alone for common bacterial infections - bacteriostatic / resistance, malaria, CNS toxoplasmosis
- synergistically used with trimethoprim
-
trimethoprim
- blocks later step in folic acid synthesis pathway
- inhibits bacterial DHFR
- alone - bacteriostatic, with sulfonamides - cidal
- Broad spectrum -
G+ and G-, not pseudomonas, not anaerobes, not atypical bacteria* - oral admin, wide distribution, good absorption, excretion in urine
- resistance increasing - location dependent
- Can cause anti-folate effect
-
ciprofloxacin, levofloxacin, and moxifloxacin
- fluoroquinolones (fluorine substitution) - most modern quinolones, greater potency, expanded spectrum (better G+ coverage)
- bactericidal - concentration dependent killing
- rapid inhibitors of bacterial DNA synthesis (inhibits DNA gyrase, topoisomerase, blocks DNA unwinding, induces irreversible DNA damage)
- oral or IV
- distribution - wide and high bioavailability, CSF low, forms chelates with cations, reduces absorption
- elimination: hepatic or renal, depending on drug
- spectrum: G- including pseudomonas where cipro > levo > moxi
- G+ including Streptococci where moxi > levo > cipro
- poor anaerobic activity
- excellent against nosocomial infections, atypical bacteriaresistance: increasing resistance, nearly all MRSA, N gonorrhea, Salmonella, Campylobacter
- adverse effects: generally well tolerated
, GI issues common, Achilles tendon rupture (rare), MRSA and C diff colonization, arthropathy in juvenile rats - use: complicated UTI, serious acute bacterial prostatitis, pneumonia, STDs, majority of use is considered inappropriate, contraindicated in pregnancy
-
polymyxin B
- cationic detergent
- use: superficial skin lesion and eye infections, G- infections only
- adverse effects: highly toxic
- topical
-
daptomycin
- membrane depolarization
- IV
- use - similar to vancomycin (G+ microbes) but treats VREF and MRSA
- adverse effects: myopathy
-
rifaximin
- binds bacterial RNA polymerase, inhibits RNA synthesis
- oral
- use: travellers diarrhea, also IBS-D
- adverse effects: well tolerated
-
nitrofurantoin
- complex mechanism: converted to highly reactive species by bacterial reductases, disrupts DNA/RNA/protein synthesis
- oral
- contraindicated with renal insufficiency
- important alternative oral agent for uncomplicated UTI
-
metronidazole
- selective reduction and accumulation of toxic products in anaerobes = dirupts bacerial DNA
- use: prophylaxis and therapy - anaerobes (bacteroides and C sp), C diff
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