Gram positive and gram negative bacteria synthesize them Gram positive

Gram positive and gram negative bacteria synthesize

This preview shows page 2 - 4 out of 10 pages.

Gram-positive and gram-negative bacteria synthesize them.Gram positive organisms produce large amounts of these enzymes and then export them into the surrounding medium.Gram-negative bacteria produce penicillinases in relatively small amounts and then secrete them into the periplasmic space.Transfer resistance is of special importance with Staph. Aureus,at first all of these strands were sensitive however later only 80% was then a penicillin derivative came out (methicillin) that has resistance to the actions of beta-lactamases.oAltered Penicillin-Binding ProteinCertain bacterial strains known as Methicillin-Resistant Staphylococcus aureus (MRSA) have a unique mechanism of resistanceProduction of PBPs with a low affinity for penicillin’s and all other beta-lactam antibiotics.MRSA developed this ability by acquiring genes that code for low-affinity PBPs from other bacteria.Staph. Aureus is a gram-positive bacterium that often colonizesthe skin and nostrils of healthy people. There is healthcare-associated MRSA (HCA-MRSA) and community associated MRSA (CA-MRSA) of the two healthcare associated is more prevalent.oChemistryProperities of individual penicillins are determined by additions made to the basic nucleusAffinity for PBPsResistance to penicillinasesAbility to penetrate the gram-negative cell envelopeResistance to stomach acidPharmcokenitics properties.
oClassificationBased on the anti-microbial spectrum, making the penicillin fallinto 4 categoriesNarrow-spectrum penicillin that are penicillineases sensitive: Penicillin G and V (streptococcus species, Neisseria species, many anaerobes, spirocetes)Narrow spectrum peniciilins that are penicillinease resistant (antistaphyiococcal penicillin): Nafcillin, Oxacillin, Dicloxacillin (Staph. Aureus)Broad-spectrum penicillin (amniopenicillins): Ampicillin, Amoxicillin (Haemophilus influenza, E.coli, Proteus mirabilis, enterococci, Neisseria gonorrhoeae)Extended-spectrum penicillin (antipseudomonal penicillin): Ticarcillin, Piperacillin (same as broad spectrum penicillins plus Pseudomonas aerguinosa, Enterobacter specier, Proteus (indole positive), Bacteroides Fragilis, many Klebsiella.oPenicillin G (benzylpenicillin)Drug of choice for many infectionsActive agonist most gram-positive bacteria (except for penicillinases-producing staphylococci), gram-negative cocci (Neisseria meningitides and non-penicillinase-producing strains of Neisseria gonorrhoeae), anaerobic bacteria, and spirochetes (including Treponema pallidum).Therapeutic uses: important for pneumonia and meningitis (caused by N. meningitides (Meningococcus)) caused by Streptococcus pneumonia (pneumoncoccus), pharyngitis caused by Streptococcus pyogens and infectious endocarditis caused by Streptococcus viridans also preferred for a few strains of Staph. Aureus that do not produce penicillinases.

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture