Drugs & Bugs Unit II Flashcards by T L

Nisseria Meningitis Gram ?

Gram -

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3 Gram + Cocci

Staph
Strep
Entero

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Localized, cutaneous abscess poss. after cut or foreign body

Staph. Aureus
Catalase + –> fibrin capsule
created by bact AND host

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Staphylococcus Epidermitis
Catalase ?

Other pertinent infection property and what does it like to stick to?

Catalase Negative–> no abscess
makes slime
sticks to foreign bodies - catheters, pacemakers, prosthetic hips etc
.nl. flora, usually not pathogenic in healthy ppl.

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ClostridiumGram ?C or R

C. diff after antiB. tx –> nl. flora killed, C. diff prolif.

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Clostridiumbreaths?

Anaerobic.
Killed by O2
Forms spores (endospores) which can tolerate O2

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Staphylococcus major resistance problem?

Penicillinase production

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How can penicillinase gene be transmitted from bact. to bact?

bacteriophage - plasmid

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What does Beta-lactamase do?

Produced by bact., induced to do so by presence of penicillins,
Hydrolyzes beta lactams

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PCN works on stage ? of c.w. synth?

Vanc. on stage ?

PCN, Ceph stage 3

Vanc. stage 2 –> works on MRSA

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MRSA mode of resistance?

bact. alters its penicillin binding protein (stage 3 of c.w. synth)

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Pen G doesn’t work well on what type of bacteri?

Gr. —> doesn’t penetrate outer membrane very well

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Oral Absorption for Pen G, V and Piperacillin?

Pen G - crappy
Pen V - good (acid stable)
Piperacillin - crappy - IV only

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What is special about Dicloxacillin?

PCN-ase resistant and available orally

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Give Piperacillin with what other drug? Why?

Tazobactam (Pip-Taz)–> is a Beta Lactamase inhibitor

–> effectively extends the spectrum of piper.

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If you want low, sustained drug levels to fight endocarditis-syphilis, use what drug and what route?

Pen G

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Name two extended spectrum penicillins.

What are the additional bugs they are good for?

Amoxicillin
Ampicillin

-Rods
E. Coli, H. flu

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Piperacillin’s claim to fame bug?

Route?

Pseudomonas 
Bacteroides (and other anerobes)

IV only

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How are most Penicillins excreted and rough half-life?

Renal

half-life 1-2 hours

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Name a drug that will block renal excretion of penicillins and what is its method of action?

Probenecid…blocks tubular secretion to prolong duration of action

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Penicillin…weak acid? weak base?ionized or not at physiologic pH?

weak acidionized at phys. pH

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Better oral absorption…Pen G or V?

More effective…Pen G or V?

Pen V. acid stable- better oral

Pen G - more effective used IV for hospitalized pts with serious infections

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Penicillin G is awesome because…

powerful and inexpensive

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Methicillin is no longer available…what drug has replaced its niche?

Nafcilin

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Draw-back of penicillinase-resistant penicillins?

less potent against Pen-G bugs But good for PCN-ase producers

Prototypical penicillinase-resistant penicillin?

Methicillin.

Spectrum of dicloxacillin?

narrow+/- C

What makes Amoxicillin and Ampicillin wider spectrum?

increased hydrophobicity ---> can penetrate porins of Gr (-) bugs give in Amox in concert with Clavulanate to extend to PCN-ase bugs.

Which penicillin is anti-pseudomonal? What are the other bugs it is good for?

Piperacillin. also kills B. fragilis and enterococci (+AG)useful in anaerobic infections

Name two beta-lactamase drugs and what they are typically combined with.

Clavulanic acid (Amox) Tazobactam (Piper)

Name the genus of the 3 gram positive cocci we are responsible for.

Streptococci EnterococciS taphylococcus aures

Name the genus-species of two gram negative cocci.

Neisseria memingitis Nisseria gonorrhoeae

Nisseria gonorrhoeae is resistant to what drug?

Pen G

Name two gram negative rods. (bacilli) and what drugs are useful against them.

E. Coli Pseudomonas Amox / Ampi +/- clavulanate for the E. Coli Piperacillin - Tazobactam for the pseudomonas

Bacteroides fragilis Gram ? rod? cocci? Drug?

Gr - Rod Piper-Tazo

Some adverse reactions of Penicillins...

"Virtually non-toxic" except for hypersens. rxns Type I rxns: rare, IgE / Histamine mediated (Mast Cells)rash - mile, reversible, idiopathic Diarrhea - common Other: seizures, salt imbalance, Jarisch-Herxheimer rxn- syphilis tx

Cephalosporin mechanism of action?

sim. to PCN. Cell wall synth inhib stage 3

Why are Cephalosporins bettern than penicillins?

broader spectrum vs. gram negative less susceptible to B-lactamases less cross reactivity in PCN sensitive pts

A distinguishing feature of 3rd generation cephalosporins?

good CNS penetration

Primary excretion of Cephalosporins?...exception?

Renal excpet Ceftriaxone - renal and hepatic -> less dosing worries in renal insuff. pts.

Name two first generation Cephs. and their route of admin.

Cephalexin (po) cefazolin (IV)

First gen cephs have a spectrum similar to what penicillin?

AmoxicillinGr +/-

Name a 2nd gen. Ceph and its route of admin.

Cefuroxime - po, IV

2nd gen Cephs have little/no action against what bug?

pseudomonas

2nd gen are better at penetrating what?

the gram negative envelope they are also great at binding the PBP's of the 3rd stage of cell wall synth

Do 2nd gen Cephs have activity against any anerobes?

yes...bacteroides fragilis

Name a 3rd gen ceph. and its route of admin.

Ceftriaxone - IV/IM

Name DDI of one of the Ceph. generations.

2nd gen - Warfarin enhancingincreased anti-coag.

How does Pen G & V work to inhibit cell wall synth?

1. Bind penicillin binding proteins 2. block transpeptidase linking of peptidoglycans 3. activate autolytic enzymes

common sites of infection of enterococcus fecalis?

urinary biliary surgical wounds

What % of pts report PCN allergy?

10%

Adverse Rxns of Vancomycin? Which is most severe?

fever, chillsr ash (infusion rxn) Ototoxicity (most severe)

How does one prevent the ototoxicity of vancomycin?

1. pretreat with acetominophen and diphenhydramine | 2. more purified preparations reduce all ADR's

Drug used as alternative to Vancomycin (for VRSA, VRE)

Daptomycin acts at bact. cell membrane, loss of ions --> cell death. restricted use ADR: GI, fever HA, dizzy

Drugs with Broader or Narrower spectrum are more likely to cause Superinfection?

Broader --> more likely cause SuperInf. e.g. Amox broader than PenG --> Amox more likely to cause superinf.

Neisseria Gonorrhoea ...gram + or - ? | Drug of choice and why.

Gr. - | Cephalosporin. not PenG b/c resistance.

Drug of choice for nasty E. Coli (gr -)?

Amox or Ampi

Drug of choice for pseudomonas (anerobe)?

Pip-Taz

Drug of choice for anthrax or diptheria (+R)

PenG | nothin' like a classic!

Penicillins are generally effective for anaerobes except...

Bacteroides. Piper-Taz is the penicillin of choice for Bacteroides

Is Pipercillin - Tazobactam effective for MRSA?

No.

Where does Bacteroides like to hang out and cause infections? What form does the inf. usually present as?

Intraabdominal, Brain Abscess

What adverse rxn is possible when treating syphilis with PenG?

Jarisch-Herxheimer rxn | spirochetal antigens relesed...cytokine storm

Which drugs are more likely to cause diahhrea?

Extended / Broader Spectrum Amox-Clav > Ampi > Amox > Pen V

Why is Ampicililn more likely to cause diahhrea than Amox (w/o clav)?

poorer oral absorption kills more nl. gut flora b/c stays in gut

What is the most use limiting ADR for penicillin? | What is most common?

Type 1 Hypersensitivity (Allergy) Diahhrea

If a pt. is allergic to penicillin what is the "go to" alternative?

Cephalosporins

Which penicillin does ceph. have the the most cross-reactivity with?

amox

Distinguish among enterotoxin, cytotoxin and neurotoxin.

enterotoxin: cause watery diarrhea by acting on secretory mechanism in intestinal mucosa cytotoxin: inflammatory diarrhea by destruction of intestinal mucosa neurotoxin: act directly on central or peripheral nervous system

Distinguish C. difficile toxin A & toxin B

Toxin A: enterotoxin Toxin B: cytotoxin Toxin B is main virulence factor. Disrupt cytoskeleton --> loss of cell shape, adhesion, tight junctions---> fluid leakage, pseudomembrane formation

Treat C. difficile infection with what antibiotic(s)? Route?

Vancomycin Metronidazole (preferred) Oral route preferred. Possible complication of CDI is adynamic ileus (toxic megacolon, sepsis) and in such cases the IV tx may not reach high enough levels in the GI tract. IV is successful if bowel is moving (acute diarrhea phase)

Three types of toxins produced by Staph. aureus

1. Cytotoxin 2. Pyrogenic toxin Superantigen 3. Exfoliative toxin

Three toxin-mediated illnesses caused by Staph. aureus

Scalded skin syndrome TSS Food poisoning

Word Association: Diptheria Toxin

EF-2 alteration inhibit protein synthesis

Which two drugs are routinely monitored for Cp levels?

Vancomycin | Aminoglycosides

Would you ever give Vancomycin orally?

Yes, if for a GI infection: C. difficile Otherwise, IV due to poor oral absorption