ID: Antibiotics Flashcards by jake ernst

Dapsone is a _______ drug, used mainly in treating what disease?

Sulfa ; Mycobacterium Leprae

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Describe the MOA of Bactrim.

Trimethoprim - inhibits dihydrofolate reductase

Sulfamethoxazole: inhibits dihydropteroate synthetase

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What class of antibiotics does Vancomycin belong to? What is it’s MOA? What is the appropriate initial loading dose? How is it monitored?

Glycopeptides - inhibits cell wall synthesis similar to b-lactam antibiotics

15-20 mg/kg load
Trough after 3rd or 4th dose . at least 10-15 mcg/ml level

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What pathogens are covered by Linezolid? What is it’s mechanism of action? What medication should be avoided concomittant with this antibiotic?

Most Gram + cocci ( staph, strep, enterococcus)
Binds 50s ribosomal subunit ( similar to macrolides)
Do not give with MAOI’s or SSRI’s ( Serotonin Syndrome)

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When should vancomycin troughs be measured?

after 3-4th dose, the medication should reach steady state. Goal is 10-15 mcg/ml

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How is vancomycin cleared?

Renal, as unchanged drug. Clearance is directly related to creatinine clearance.

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What are the 4 b-lactam antibiotic classes?

Penicillins, cephalosporins, carbapenems, and monobactams

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What coverage does Aztreonam provide? Why prescribe it?

Strictly gram - coverage, ok for those with PCN allergies

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Cefazolin and cephalexin are ________ generation cephalosporins.

First Generation

Mostly Gram + coverage, some gram - like e.coli

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Which penicillin is given orally? Intravenously?

Pen G is given IV. Pen VK is oral.

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What is the general MOA of all b-lactam antibiotics?

They interact with penicillin binding protein, disrupting cell wall synthesis ( peptidoglycan to be precise.)

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What is the bacterial activity of the natural penicillins?

Aerobic gram + ( staph, strep, enterococcus, listeria)
Aerobic gram - ( nisseria , haemophilus)
Anaerobic ( clostridium… except c.diff)
Spirochetes ( treponema and leptospira)

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Antistaphylococcal penicillins include___.

Oxacillin/ Nafcillin

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The aminopenicillins include _____ and ____.

Amoxicillin and ampicillin

addition of beta-lactamase inhibitors such as sulbactam/clavulanic acid are common

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Borellia burgdorferi can be treated with which penicillin drugs?

amox/ amp or augmenten

Primary regime is doxycycline unless contraindicated. (age

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What is the most common extended spectrum penicillin drug?

Pipercillin/ Tazobactam (Zosyn)

Ticarcillin / clavulanate)

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Coverage of Zosyn?

Gram +
Gram - (neisseria, h. flu, enterobaceteriacea, pseudomonas )
Anaerobes ( clostridia, except c.diff, and bacteroides)

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What organisms are included in the enterobacteriaceae family?

Shigella, salmonella, e.coli, klebsiella, proteus, serratia …to know most important ones

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Cefoxitin/ Cefuroxime are ______ generation cephalosporins.

second

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Cefotaxime and ceftriaxone are _____ generation cephalosporins.

Third

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This 4th generation cephalosporin has broad coverage of gram - and + bacteria as well as pseudomonas.

Cefepime

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Ceftaroline is the only commercially available ____ generation cephalosporin.

Fifth

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What two 2nd generation cephalosporins have moderate anaerobic bacterial coverage?

Cefoxitin and cefotetan

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What percentage of PCN allergic people will have a cephalosporin reaction?

5-10%

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Why is imipenem administered with cilistatin?

The abx is rapidly degraded in the kidney by dhydropeptidase I. Cilistatin inhibits this enzyme Notably, the other carbapenems dont have this requirement.

Which carbapenem only requries qd dosing? What is the disadvantage of this drug?

Ertapenem is qd. However it sacrifices gram + coverage and pseudomonal and acinetobacter coverage because of that property.

A feared complication of carbapenem drugs is ______, meaning it should not be administered to patients with what underlying disorders?

Seizures. Avoids in patients with previous seizure disorder, renal insufficiency.

This medication has strict gram - coverage and can be viewed as a non-toxic alternative to aminoglycosides, or patients with PCN allergy.

Monobactams ( Aztreonam)

This lipopeptide antibiotic is active against gram + organisms, many resistance strains of staph and strep and VRE.

Daptomycin

This older antibiotic has limited gram - coverage of pseudomonas, most enterobacteriaceae, and H. influenza. It is moderately nephrotoxic and neurotoxic.

Colistin

________ exhibits limited coverage of staph, niesseria, and mycobacterium species, and causes red discoloration of tears and urine.

Rifampin

The most potent inducer of the CYP450 system is _____.

Rifampin

Major side effects of aminoglycosides include ______.

nephrotoxicity ( 5-10% in patients without other risk factors) and ototoxicity.

Macrolides exert their antimocrobial effect via _____.

Binding the 50s ribosomal subunit

In addition to atypical bacterial infection coverage, ________ also over coverage of some gram +, gram -, spirochete and mycobacterial infections .

macrolides

The advantage of this medication is that it is taken up quickly by body tissue and released over subsequent days, making a 5 d course effective for 10 days.

Azithromycin

What are the feared toxicities of macrolide antibiotics?

QT interval prolongation and Cytochrome inhibition ( except azithromycin)

Decolonization of MRSA is effective about _____ % of the time ,and consists of what regimen?

60-65% Doxycycline bid x 14 d and Rifampin on last 3d Mupirocin ung for new lesions Chlorhexidine body wash bid Chlorhexidine mouth gargle bid-tid total of 14 days of treatment

Tetracyclines mechanism of action.

Bind 30s subunit of ribosome

This class of fairly broad spectrum antibiotics exhibits decent aerobic gram + ( S. pneumoniae), gram - ( h. flu and neisseria), anaerobic ( c/diff) , spirochetes and rickettsial species.

tetracyclines

What antibiotics are included in the tetracycline class?

Doxycycline tetracycline minocycline Tigecycline

Which tetracycline is preferrable in tx of MRSA?

Minocycline Hence why it is a good choice for hidradenitis supp.

This newer tetracycline has an impressive broad spectrum activity against aerobic gram + and -, anaerobic and atypical pathogens.

Tigecycline

Aplastic Anemia and Gray Baby Syndrome are feared side effects of this older, but very broad spectrum antibiotic.

Chloramphenicol

This popular lincosamide antibiotic has seen resurgence recently due to its good activity against MRSA. Available in both oral and IV formulation.

Clindamycin

Clindamycin has been associated with an incidence of up to 10% of this side effect.

Bacterial Pseudomembranous Colitis 2/2 Clostridum difficile

Is Clindamycin active against aerobic gram - bacteria?

Nope

Would clindamycin be a reasonable choice to cover for pseudomonas, brucella, legionella, or any of the enterobacteriaceae species?

No. Clinda has no gram - coverage.

This synergistic antimicrobial combination has broad aerobic gram + cocci activity.

quinupristin/dalfopristin

quinupristin/dalfopristin should only be given via what route? a) peripheral IV b) central IV access c) PO d) suppository

B - causes pain/thrombophlebitis Also a cyp 450 inhibitor

This synthetic antibiotic available in PO or IV formulation has excellent gram + coverage, especially against MRSA and VRE.

linezolid

Linezolid should not be given concurrently with what other depression medication?

MAOI or SSRI - potential for Serotonin Syndrome ,as linezolid is also a monoamine oxidase inhibitor

This niche antibiotic achieves low levels in blood but concentrates well in urine, making it effective against most UTI pathogens.

Nitrofurantoin

Nitrofurantoin is not active against what important urinary pathogens?

proteus mirabilis and pseudomonas aeruginosa

Would Macrobid be a good choice in the treatment of pyelonephritis ? What about cystitis ?

Cystitis - yes | Pyelo - no - poor concentration in renal parenchymal tissue

General coverage of sulfa drugs includes ?

some strep/staph, listeria, h. flu, some enterobacteriaceae, and m. leprae

MOA of fluoroquinolone abx?

DNA Gyrase/ Topoirsomerase IV inhibitors Cipro, levo, moxi, gatiflox, ofloxacin

This fluoroquinolone exhibits somewhat weak gram + coverage, but excellent gram - and pseudomonal coverage.

Ciprofloxacin

Ofloxacin and levofloxacin are similar in what way?

Both contain sterioisomers , ofloxacin being a mixture of active and inactive isomers, levofloxacin being composed of only the active isomer.

This fluoroquinolone has excellent activity against s. pneumoniae and decent pseudomonal coverage.

Levofloxacin

This fluoroquinolone has an methoxy group, making it more potent against anaerobic pathogens.

Moxifloxacin

These newer fluoroquinolone agents have enhanced activity against s. pneumoniae, including resistant strains .

Moxifloxacin/ Gemifloxacin

Cartilage abnormalities are a potential side effect of these antibiotics.

Fluoroquinolones

This niche antibiotic only exhibits activity against anaerobic pathogens.

Metronidazole (Flagil)

Due to disulfram like reaction, ingestion of alcohol should be avoided with this agent.

Metronidazole

This agent has some activity against microaerophilic pathogens such as H. pylori .

Metronidazole

This component can be co-administered with isoniazid in the treatment of TB in order to reduce rates of the side effect of peripheral neuropathy.

pyridoxine ( Vit B6)

This anti-mycobacterial agent causes elevations in uric acid, and may precipitate gout.

Pyrazinamide

This anti-mycobacterium drug can cause optic neuritis and decreased red/green discrimination.

Ethambutol

These anaerobic gram + pathogens are found in the human GI tract, but when insult or compromise occurs can cause UTI, intraabdominal infections, meningitis, endocarditis and bacteremia.

Enteroccocus E. Faecalis ( only about 2% resis tance) E. faecium ( high resistance to vancomycin - VRE infection)

This is the only known bacteriostatic agent against L. monocytogenes.

ampicillin Note that gentamicin can be given synergistically .

Inhalation of these spores cause a pulmonary condition characterized by blood pleural effusions, bleeding mediatinal lymph nodes, and bacteremia.

B. anthracis

This bacterium is resistant to cephalosporins, which are normally used as empiric therapy for meningitis.

L. monocytogenes

This enteric gram - pathogen is the leading cause of meningitis in neonates.

E. coli

This enteric pathogen is the leading cause of pneumonia in patients with hx of alcohol abuse.

Klebsiella pneumoniae

This particular strain of b-lactamase producing gram - enteric pathogen exhibits a gene mutuation, making it resistant to most b-lactam antibiotics. It has been treated successfully with tigecycline, colistin, or aminoglycosides.

KPC Klebsiella pneumniae carbapenemase

These resistant gram - pathogens are resistant to most all b lactam antibiotics, with the exception of carbapenems and some b-lactamase inhibitor combinations.

ESBLs extended spectrum b lactamase mutated strains

Patients with cystic fibrosis are generally chronically infected with this pathogen by adulthood.

P. aeruginosa

Because of worrisome resistance emerging DURING treatment, this pathogen is often treated with synergistic abx such as a b-lactam + aminoglycoside or B-lactam + appropriate fluoroquinolone .

P. Aeruginosa example regimens Pip/tazo + ciprofloxacin ceftazidime + tobramycin

In documented cases of N. meningitidis, close contacts will be given abx prophylaxis with what?

Rifampin or Rocephin or Ciprofloxacin

What are some acceptable examples of triple or quadruple therapy for treatment of H. pylori gastritis/ PUD.

Amox or Flagyl + Clarithromycin + PPI Bismuth subsalicylate + flagyl + tetracycline + PPI

This pathogen has been associated with Musoca Associated Lymphoid Tissue (MALT) Lymphoma .

H. pylori

With the advent of a conjugate vaccination, this pathogen and it's type B antigenic envelope have become much less common.

H. influenzae type B

The drug of choice for treatment of tracheobronchitis 2/2 B. pertussis .

Macrolides ( Zithromax)

This gram - coccobacillus is an important cause of hospital and community acquired pneumonia, bacteremia and wound infections.

Acinetobacter spp.

This anaerobic pathogen is a well known spore former, allowing it to lie dormant and activate during opportunistic times.

Clostridia spp.

Inoculation of the spores of this pathogen into a deep wound can cause a syndrome characterized by tonic spasms of the masseter muscles, and muscles of the trunk.

Clostridium tetani. (Tetanus/ Lock Jaw)

TOC for tetanus.

Flagyl or penicillin

Gas gangrene is caused by what pathogen?

C. perfringens

Treatment for mild to moderate C. difficile? | What about severe disease?

Metronidazole | Oral vanc for severe case

Which two cephalosporins exhibit good anaerobic coverage?

Cefotetan and Cefoxitin

This anaerobic gram - baccili is associated with intraabdominal infections, abscess, PID, and pleuropulmonary infection. Often associated with polymicrobial infection.

Bacteroides spp. Specifically B. fragilis .

Definition of severe c. difficile?

varies but in general WBC .15-20k, failure to improve, cr >1.5 or albumin

Treatment for mild and sever CDI?

Mild - Metronidazole 500 mg tid x 10-14 d Severe- oral vancomycin 125 mg tid 10-14 d OR fidaxomicin 200 mg bid 10-14 d

What is the major advantage from a pharmacologic perspective in using fidaxomicin instead of vanc or flagyl ?

Difficid is bacteriocidal against C. diff, whereas vanc and flagyl are bacteriostatic.

A patient with documented C. difficile infection on oral vancomycin fails to improve over the course of hospitalization, with WBC of 15, 000, albumin 2.4, lactate of 2.8, and develops abdominal distention and diminuation of diarrhea production. What is likely occurring? What is the best course of action?

possibly developing toxic megacolon. the diminished diarrhea and distention could represent loss of colonic muscle tone. Recommend CT scan. Possible surgical consultation for colectomy. Consider treatment with fidaxomicin?

Should probiotics be administered in patients with C/ diff in order to prevent or reduced clostridium difficile associated diarrhea (CDAD)?

yes. Studies to indicate a modest but statistically significant reduction in diarrhea in patients treated with probiotics .