Anaerobic bacteria are intrinsically resistant to
(B) Aminoglycosides[?]Mechanism of Antibiotic ResistanceoIntrinsic (natural resistance) resistance:--Innate ability of a bacterial species to resist the activity of a particular antimicrobial agent through inherent structural or functional characteristics, allowing tolerance to a particular drug or antimicrobial class.-Intrinsic mechanisms of resistance are an innate characteristic of the microorganism and are transmitted to progeny vertically (i.e. during cell division)-Eg. Anaerobes are intrinsically resistant to aminoglycosides.INTRINSIC RESISTANCE IN BACTERIAOrganismsAntibioticsMechanismGram-positive bacteriaAztreonam (beta-lactam)Lack of penicillin binding protiens which can effectively bind aztreonamGram-negative bacteriaVancomycinLarge molecule of vancomycin is unable to penetrate outer membrane of G-ve bacteriaKlebsiella spp.Ampicillinb-lactmases produced by the bacteria destroy ampicillin before it reaches the PBP target.Stenotrophomonas maltophiliaImipenemb-lactamase produced by bacteria destroy imipenem before it bind with PBPLactobacillus & LeucomostocVancomycinUnable to bind with cell wall precursorPsudomonas aeruginosaSulfonamides, trimethoprim, tetracycline, chloramphenicolIn-effective intracellular concentrations of antibiotics due to lack of uptakeEnterococcus spp.AminoglycosidesLimited uptake of aminoglycosides by protein of electron transort chainb-lactam antibiotics like penicillin, cephalosporins & monobactamLack of penicillin binding proteins MECHANISMS OF RESISTANCE. Intrinsic Resistance. Analogous to innate (non-specific) human immunity. Examples: Obligate anaerobic bacteria to aminoglycosides; Gram (-ve) bacteria to vancomycin. Acquired Resistance. Analogous to specific action of human immunity. Bug, over time, develops resistance to specific mechanism of action- Mutation of resident genes, or Acquire new genes and incorporate into own DNA. Major problem with over-prescribing antibiotics.. Pt demands (stronger) antibiotic and practitioner gives in (viral URI, viral pharyngitis).. Selects for those organisms, with resistance, proliferation, further.n. Mechanism of Antibiotic Resistance:. Intrinsic (natural resistance) Resistance:. Innate ability of a bacterial species to resist the activity of a particular antimicrobial agent through inherent structural or functional characteristics, allowing tolerance to a particular drug or antimicrobial class.. Intrinsic mechanisms of resistance are an innate characteristic of the microorganism and are transmitted to progeny vertically (i.e., during cell division).. Eg., Anaerobes are intrinsically resistant to aminoglycosides.
Beta lactams
Aminoglycosides
Chloramphenicol
Metronidazole
Bacteria