Glossary of Pharm: Antibiotics I

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gram staining is used to...
-identify the uniue peptidoglycan cell wall of baceteria
-differentiate between postive gram positive and gram negative bacteria
Gram stain procedure:
1. stained with crystal violet
2. treated with 1:15 dilution of Lugol's iodine
3. decolorized with ethanol or ethanol-acetone
4. coounterstained with constrasting dye, usally safarin
Gram staining results:
gram postive - retain crystal violet stain (blueish)

Gram negative - lose crystal violet stain by decolorization but maintain the counterstain (reddish)
What are analytical tests used for?
To detect unique molecules such as proteins, carbohydrates, or DNA
What are some examples of analytical tests?
-western blot analysis
-polymerase chain reaction (method of amplifying or copying DNA fragments that is faster than cloning)
-DNA fingerprinting (process using fragments of DNA to identify the unique genetic makeup of an individual0
-sequencing of DNA (to determine the order of the base pairs in a segment of DNA)
What tests can you do to test for antibiotic susceptablility?
-disc diffusion
-dulation susceptability tests

These help identify the species of bacteria as well as the type of ABx that may be useful to treat the infection
What should be considered when deciding which Abx to use?
-age and health status of the individual
-drug resistance in the community
-penetration of ABx at the site of bacteria
-drug's side effect profile
-drug metabolism esp if pt has malfunctioning organs that eliminate the drug
-concurrent meds
What is bacteriostatic?
arrest the growth of the organism which allows the immune system to eradicate it
What is bacteriocidal?
eradicate the microorganism by exerting their concentration dependent killing time or time dependent killing activities
What are the 2 types of bacteriocidal?
concentrations dependent


How do concentration dependent bacteriocidals work?
increasin serum levels of the ABx will enhance its effectiveness

How do time dependent bacteriocidlas work?
require a certain amount of time in order for them to exert their effect
What is the postantibiotic effect?
Abx that have an effect even after their effective serum levels dip below the optimal levels

protein synthesiss inhibitors
DNA synthesis inhibitors
Drugs metabolized in the liver are likely to have which side effects?
-increase effect of warfarin since it is also metabolized in the liver (circulating levels of both the drug and warfarin are likely to increase ince the liver has a limited capacity for drug metabolism)

Are nosocomial (hospital acquired) viruses more or less difficult to treat?
more difficult to treat since resistance emerges to one of more Abx
What are the strategies used by pathogens to develop resistance to ABx?
1. destruction /metabolism/ inactivation of the drug (e.g. beta lactamases)
2. mutation of the ABx binding site (macrolides, lincosamides, and streptogramins later 50S subunit)
3. Down regulation of porin in cell membrane (aminoglycosides, fluoroquinolones)
4. ABx eleiminated from cytoplams via energy-dependent drug efflux (tetracycline)
5. Resistance is transmitted via plasmids within a population of chromosomes accross generations
Which bacteria are especiialy difficult to kill?
-methicillin resistant stephylococcus aureus (MRSA)
-pseudomonos auruginosa
-vancomycin resistant enterocci (VRE)
-clostridium difficile
What other things can be treated with Abx aside from bacteria?
All Abx inhibit 1 of 4 main processes in the micoorganisms. What are the 4 main processes?
-cell wall synthesis
-protein synthesis
-folate metabolism
-DNA transciption, replication, and metabolism
What are the cell wall inhibitors?
-cephalosporins (1-4 generation)
-carbepenams and monobactam
-vancomycin and teichoplanin, fosfomycin, bacitracin, and cycloserine
What are the protein synthesis inhibitors at the 50S subunit?
-streptogramims and oxazolidinones
What are the protein synthesis inhibitors at the 30S subunit?
What are the folate metabolism inhibitors?
What are the DNA rplication, transiption, and metabolism inhibitors?
What are the urinary tract antiseptics and other antibiotics?
What is the chemistry of the Penicillins?
-thiazolidine ring
-beta lactame ring
-secondary amino group
What is the only natural penicillin?
panicillin G

used in the form of benzathine, procaine, K+, and Na+ salts
What is the semisynthetic penicillin?
Penicillin V
What are the isoazolyl penicillins (oral)?
What are the amino penicillins (oral)?
-ampicillin (principen)
-amoxicillin (amoxil)
What are the carboxyl penicillins?
-carbenicillin (geocillin)
-ticarcillin (timentin)
What are the acyluredo penicillins?
-piperacillin (Pipracil)
What are the anti-pseduomonal Penicillins?
What is the mechanism of aciton for pencillincs?
-inhibit cell wall synthesis by inhibting the transpeptidase that cross links peptidoglycan molecules (which ultimately gives the cell wall its regidity)
Are penicillincs broad or narrow spectrum?
Are penicilins bacteriocidal or bacteriostatic?
bacteriocidal if cells are growing and making new cell walls
What are the narrow spectrum penicillins?
-PCN G and V
-anti-staphylococcal PCN
What are the broad spectrum penicillins?
-carboxyl penicillins
-acylureido penicillins
What do the natural penicillins cover?
-gram (+) organisms
-some gram (-) cocci
-many anaerobes and spirochetes
Listeria monocytogenes is sensitive to _____ but no to _____
sensitive to penicillin G but not to cephalosporins
Anti-staphylococci PNC in ineffective against...
What do broad spectrum penicillins cover?
-gram pos organims
-increased coverage for gram neg organisms
-many anaerobes and spirochetes
WHat are the only PNC that are effective against psuedomonas aeruginosa?
-carboxyl and acylureido PNC
What do narrow specturm pencillins cover?
-gram pos
-a few gram neg
-some anaerobes
PCNs are ineffective against...
-methicillin resistant staph aureas (MRSA)
-vancomycin resistant enterococci (VRE)
-legionella sp
-mycobacterium pneumoniae
PNC: CLinical uses
-hospital acquired penumonia
-bone and jt infections
-chronic UTI
-acute otitis media
-syphilis (PCN G)
-prophylaxis for dental procedures
In serous infections, PCN are often combined with...
another ABx such as protein synthesis inhibitor (i.e. aminoglycoside) to achieve synergistic effect
PCN: Resistance
-beta lacatmases the inactivate the drug by destroying the beta lactame ring
-mutant transpeptidases with reduced affinity for the drug
-down regulation of porins that reduces access of drug
-elimination of drig via efflux pump
What type of resistance does MRSA use?
they produce beta lactamases
What can be done to get around the problem of beta lactamases?
give ABx with a beta lactamase inhibitor (clavulanate, sulbactum, tazobactum)
What are the beta lactamase inhibitors?
-clavulanic acid
What are the combincations of PCN plus beta lacatamase inhibitors?
-amoxicilllin plus clavilanate
-ampicillin plus sulbactum
-ticarcillin plus clavulanate
-piperacillin plus tazobactam
PCN: pharmacokinetics
-oral absorption is poor
-rarely penetrate CNS
-NOT metabolized
-excreted by kidneys (except nafcillin which is eliminated by biliary excretion in feces)
Most PCN are acid labile and destroyed in the stomach except..
amino PCN
What PCN are intramuscular?
-benzathine PCN G

formulated in depot of IM admin for prlonged, slow release
PCN: adverse reactions
-few adverse effects
-allergic rxn/ hypersensitivity (1-5%)
-GI distress
-seizures and hypokalemia with large doses
If pt is PCN resistant, what are viable alternatives?
Superinfections are common with ...
ampicillin and chronic use of penicillin as well as other ABx

the elimination of normal flora with prolonged antibiotic administration especially with extended or broad spectrum activity can allow other microogranisms to colonize
overgrowth of closteridium difficile causes....
pseudomembranous colitis

potentially lethal
Penicillins: Drug interactions
-aminoglycosides: reduces activity of both ABx
-probenecid inhibtis the excretion of PCN and increases plasma levels
Beta Lactamase Inhibitors: Chemistry
-beta lactame ring (like PCN and cephalosporins)
-NO microbial activity of their own
Beta Lactamase Inhibitors: Mechanism of action
-irreversibly bind to beta lactamases
-inhibit many but not all bacterial beta lactamases (which are the enzymes that can hydrolyze and thus inactivate PCNs)
Are beta lactamase inhibitors Antibiotics?
NO, they are not antibiotics

They are neither bacteriostatic or bacteriocidal
Beta lactamase inhibitors: Clinical uses
-given in combo with PCN to treat septicemisa, community/hospital acquired pneumonia, cellulitis, sinusitis, bone/jt infections
beta lacatamase inhibitors: pharmakokinetics
-clavulanate is aborobed orally
-sulbactam and tazobactam are given systemically d/t poor oral absorption
-access to brain
-excreted by kidneys
Beta lactamase inhibitors: adverse reactions
no significant adverse reactions
Beta lactamase inhibitors: Drug interactions
-piperacillin increases the half life of tazobactum
Cephalosporins: Chemistry
7 amino-cephalosporanic acid wherein the ring attached to the beta-lactam center has an extra carbon
(this nucleus makes ceph more resistant to beta lactamases than PCN)
Cephalosproins: 1st generation examples
Cefazolin (Ancef)
Cephradine (Velosef)
Cefadroxil (Dureicef)
Cephalexin (Keflex)
Cephalosporins: 2nd generation examples
Cefamandole (Mandol)
Cefoxitin (Mefosin)
``66Cephalosporins" 3rd generation examples
Cefoperazone (Cefobid)
Cefotaxime (Claforan)
Ceftriaxone (Rocephin)
Cephalosporins: 4th generation examples
Cefepime (Maxipime)
Cephalosporins: Mechanism of Action
inhibit cell wall synthesis by binding to and inhibiting the transpeptidase that cross links peptidoglycan molecules and ultimately gives the cell wall its rigitidy
Cephalosporins: Antimicrobial activity
-Broadspectrum antibiotics
-extended coverage against gram negative bacgteria beginning with the 2nd generation drugs and increasing with the third as well as the 4th
-cefoperazone, ceftazidime, and cefepime have coverage against pseudomonas aeruginosa
-ineffective against MRSA, listeria monocytogenes, and legionella sp
-less effective then PCN against anerobes
Which cephalosporins are active agaisnt pseudomonas?
but other G3 have no or variable activity against it
Cephalosporins are innefctive against...
-Listeria monocytogenes
-Legionella sp
Which are more effectve against anearobes - Ceph or PCN?
pcn are more effective against ceph
Cephalosporins: Clinical Uses
-hospital-acquired bacterial pneumonia
-bone and jt infections
-acute otisi media
-lyme disease (caused by spirochete)
-surgical prophylaxis
Hospital acquired bacterial penumonia are usually caused by ....
pseudomonos aeruginosa, staph aureus or other gram neg
Treatment for hospital acquired bacterial pneumonia can include:
(1) a G3 cephalosporin or G4 cefepime in combination with clindamycin
(2) ticarcillin/calvunate (beta lactamase inhibitior) or piperacillin/tazobactam plus ciprofloxacin
(3) new fluorquinoline or an antipseudomonal aminoglycoside
What is preferable treatment for gonorhhea?
ceftriaxone, cefixime, cefpodoxime, or ofloxacin in combo with doxycycline or azithromycine
What is the preferable treatment for acute otitis media?
-if amoxicillin fails after 3 days, then amoxicillin/clavulanate or cefuroxime exetil (G2)
-if pt was previously on antibiotics, ceftriaxone is recommended
Cephalosporins: resistance
similar to PCNs
mainly beta lactamases or enzymes that inactivate of the drug by breaking the beta lactame ring
-more resistance to beta-lactamases than PCNS
Cephalosporins: oral absorption
-oral absorption is variable
-oral absorption with cefadroxil, cephalexin, cephradine (all G1); cefaclor, cefuroxime axetil (G2s); cefixime, cefpodozime, ceftibuten (G3)
-all others must be given systemically
-distrubution in body is variable
-ALL G1 and G2 drugs fail to enter the brain except cefuroxime
-G3 and G4 drugs ahve extensive distrubtution into the brain and eye with the exception of cefizime, cefoperazone, and cefotaxime
Cephalosporins: excretion
-most are excreted by the kidneys via tubular and glomerular filtration except cefoperazone and ceftriaxone which are eliminated by biliary excretion into the feces
Cephalosporins: Corssing the blood brain barrier
-ALL G1 and G2 drugs fail to enter the brain except cefuroxime
-G3 and G4 drugs ahve extensive distrubtution into the brain and eye with the exception of cefizime, cefoperazone, and cefotaxime
Cephalosporins: ADverse Reactions
-hypersensitivity and allergic reactions
-GI distress such as diarrhea, vomiting, nausea, superinfections
-abnormal PT times
-disulfiram-like toxic reactions (if alocholl is ingested) are seen with cefotetan and cefoperazone
-5-15% of PCN allergic pts are also allergic to ceph
Cephalosporins: Drug interactions
Probenecid inhibits the excretion of cephalosporins as seen with PCN

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