Antibiotic Flashcards
What is the drug of choice for meningitis caused by listeria monocytogen?
Ampicillin
What is the drug used for severe staphylococcal infection like endocarditis and pneumonia ? What is the administration?
Nafcillin and oxacillin ( parenteral )
What is the drug of choice for therapy of meningitis caused by suspectible staphylococcus pneumonia? And what is the administration of the drug?
Penicillin G intravenously
What is the category of penicillin?
Natural penicillin,
anti-staphylococcal penicillin,
extended spectrum penicillin
and anti pseudomonal penicillin
Mechanism of action for beta lactams?
Inhibiting transpeptidase
Activate autolytic enzyme
Unactivate penicillin binding proteins
What is the drug that used for otitis media , bronchitis and sinusitis? What is the administration?
Amoxicillin orally
What drug is used for eradication of Helicobacter pylori and duodenal and gastric ulcers?
Amoxicillin
What drugs of penicillin are used for serious infection caused by pseudomonas areuginosa
Piperacillin, ticarcillin
Examples for natural penicillin
Penicillin G ,penicillin V
Examples for anti-staphylococcal penicillin
Nafcillin, oxacillin, and dicloxacillin
Examples for extended spectrum penicillin
Ampicillin and amoxicillin
Examples for anti pseudomonal penicillin
Carbenicillin, ticarcillin and piperacillin
The Oral absorption of penicillin varies according to
Particular penicillin used
PH of the patient’s stomach
presence of food and G.I. track
All the penicillin should be given without food, but What are the penicillin that should be taken with food?
Penicillin V and amoxicillin
What is the distribution of penicillin?
They are widely distributed in the body fluids, and It can across the placenta
The entrance to CSF is minimal except with inflammation of meninges
The metabolism of penicillin
Metabolized by hepatic enzymes
Dosage adjust might be needed
The elimination of penicillin
Renal through tubular secretion and glomerular filtration
All penicillins require dosage adjustments in renal failure.
What is the penicillin that does NOT need dose adjustment
Anti staphylococcal penicillins
The bacterial resistance to penicillin
1-Bacterial enzyme (beta lactamase/penicillinase)
2-decrease penetration to the target site
3-Inability to bind to penicillin binding protein
4-Lack for activation of autolytic enzymes
Beta lactamase are most common in what kind of bacteria
Gram-negative bacteria
What is the solution for bacterial resistance to penicillin with beta lactamase
Combined penicillins with beta lactamase inhibitors
What is the examples of combination of antibiotic with beta lactamase inhibitor?
1- agumentin ( amoxicillin + clavulanic acid)
2- unasyn ( ampicillin + sulbactam)
3- zosyn ( piperacillin + tazobactam)
What is the adverse effects of penicillin?
1-hypersensitivity
2-diarrhea
3- nephritis
4-neurotoxicity
5-hematologic toxicity
Cephalosporin are from a fungus called
Cephalosporium acremonium
What is the second choice for many infections
Cephalosporins
Cephalosporins works for what kind of bacteria?
Gram-positive and gram-negative
What kind of administration used for urinary infection while taking cephalosporins (cefaclor)
Oral
The generation of cephalosporin based primarily on
Spectrum of antibacterial activity
The basis of anti-microbial activity (including beta lactamase stability and pharmacological properties)
What is the changes if we go from the first to fourth generation of cephalosporins
1-The spectrum of activity against gram negative organisms and the stability against beta lactamase INCREASE
2- same or REDUCED spectrum of activity against gram positive organisms and pharmacokinetics differences
Which generation of cephalosporins has good activity against gram positive and against most gram negative
The fifth generation
Which generation of cephalosporins have activities against anaerobic bacteria
The second and the fifth
Which cephalosporin drugs have anti pseudomonal activity
1- ceftazidine 3rd
2- cefepime 4th
3- ceftolozane 5th
The most potent anti pseudomonal from cephalosporins is
Ceftolozane 5th “which derived from ceftazidine 3rd”
The only cephalosporins that is used against MRSA
ceftoraline 5th
The absorption of cephalosporins
Good on oral administration
Unaffected by food (except: cephradine and cefaclor for which it may be delayed)
The distribution of cephalosporins
Well distributed into most body tissue like:
Bone, pleural fluid, pericardial fluid and synovial fluid
Which cephalosporins does NOT need dose adjustment
Ceftriaxone and cefoperazone
The adverse effects of cephalosporins
Allergic manifestation: to those who had an anaphylaxis response to penicillin
Bleeding : due to anti vit.k effect
The reason behind developing carbanpenems and monobactams
To deal with beta lactamase producing gram negative resistance penicillin
Example for carbapenem
Imipenem ( broad spectrum antibiotic)
Ertapenem
Meropenem
What is been used with imipenem to block its breakdown by the kidneys
Cilastatin
What kind of administration that is used with carbapenem
IV “ NOT absorbed orally”
The adverse effect of carbapenem
Seizures
Examples for Monobactam
Aztreonam which is active against gram-negative aerobic bacteria
Resistant most beta lactamase
Aminoglycosides divided into
Systematic and topical
Systematic aminoglycoside are
Streptomycin
Gentamicin
kanamycin
amikacin
tobramycin
Topical aminoglycoside are
Neomycin
Framycetin
Does the aminoglycosides considered to be bactericide or bacteriostatic
Bactericides
Based on the mechanism of action, in what category does aminoglycosides belong to?
Interferes with proteins synthesis, 30 ribosomal subunit
Aminoglycosides used to treat what kind of bacteria
Aerobic, gram-negative bacteria
What is the adverse effect of aminoglycosides?
Ototoxicity , nephrotoxicity
What is the distribution of aminoglycosides
Distribute only extracellularly
Do not penetrate brain or CSF no not absorbed orally
What is the mechanism of action of aminoglycosides
They are positively charged bind to the negative charge of the bacterial membrane and disturb it + interfere with protein synthesis
The antibacterial spectrum of aminoglycosides is / or what kind of bacteria does the aminoglycosides work against
Gram-negative aerobic bacilli
Gram-positive cocci
NOT NOT effective against G+ve bacilli, G-ve cocci nor anaerobes
What is the pharmacokinetics of aminoglycosides
1-Highly polar=poor Oral
2-Administrated parenterally or applied locally
3-Poorly protein bound
4-No significant metabolism
5-Excreted unchanged in urine
6-Dosage adjustments is needed
Clinical use for aminoglycosides
1-gram-negative bacillary infection
(Septicemia, pelvic and abdominal sepsis)
2-bacterial endocarditis
3-pneumonias, tuberculosis
4-brucellosis
5-topical- neomycin
6-Infection of conjunctiva or external ear
Share toxicity of aminoglycosides
Ototoxicity, nephrotoxicity, neuromuscular blockage, skin rash
Which aminoglycosides are more likely to produce neuromuscular blockade
Streptomycin and neomycin
Which aminoglycosides are least likely to produce neuromuscular blockade
Tobramyosin
Which aminoglycosides are more likely to produce nephrotoxicity
Gentamicin, amikacin and tobramycin
Is the nephrotoxicity caused by aminoglycosides are reversible?
Reversible of drug promptly discontinue
Precautions and contraindication for aminoglycoside
1-pregnancy : fetal ototoxicity
2-with other ototoxic drugs: furosemide, minocycline
3-with nephrotoxic drugs: vancomycin, cisplatin
4- elderly patient
5-those with kidney disease
6-muscle relaxant
7-do not mix with any other truck in the same syringe
What is the most commonly used aminoglycosides?
Gentamicin
Why is the gentamicin or most commonly use?
More potent
Broader spectrum
Low-cost, reliability of use, long experience
Acts synergistically with ampicillin, penicillin G, ticarcillin, ceftriaxone and Vancomycin
the prototypes of Glycopeptide antibiotics are :
Vancomycin, teicoplanin
What is the mechanism of action of vancomycin?
Inhibits cross-linking of peptidoglycan which cause the destruction of bacterial cell wall
Why does Vancomycin considered important?
Because of its effectiveness against multiple drug resistant organism
Such as MRSA and enterococci
Vancomycin is effective against
Gram-positive organism and MRSA
Spectrum of activity of vancomycin
1- Effective against gram-positive, streptococci, staphylococci and pneumococci
2- effective against Neisseria spp. (only G- can work against)
3- endocarditis caused by MRSA
4- Used for treating enterocolitis associated with clostridium difficle ( since it’s not absorbed from the G.I.)
Adverse effects of vancomycin
Fever, chills, phlebitis -at the infusion site-
Flashing (red man syndrome) due to histamine release
Ototoxicity , nephrotoxicity
What is the administration bacitracin?
Locally or IM against resistance staphs
Orally for treating diarrhea especially against clostridium difficle
What is the antibiotic that used in disaffecting the gut before an operation?
Bacitracin
What is the mechanism of action of bacitracin?
Inhibits the biosynthesis of peptidoglycan by inhibition of dephosphorylation of phospholipid
What is the mechanism of action of polymyxin B?
- Forms of complex with membrane phospholipids and disrupt cell membranes
- Bactericidal but restricted to gram negative bacteria
- use locally for local infection of wounds with gram-positive antibacterial, bacitracin
- used Orally for the treatment of G.I. infection
- IM or intrathecal injection for systematic infections
What is the mechanism of action of the fluoroquinolones?
Bacteriocidal agent
They block bacterial DNA synthesis by inhibiting bacterial DNA gyrase and topoisomerase
Bacterial resistance against fluoroquinolones
Point mutations in the binding site of the target enzyme
Change in the permeability of the organism
Resistance to one fluoroquinolones confers cross resistance to all members of the class
Generation of fluoroquinolones
1st -> nalidixic acid-> G-ve NOT pseudomonas species
2ed-> norfloxacin, ciprofloxacin, ofloxacin -> G-ve +pseudomonas species + G+ve + some atypicals
3ed -> levofloxacin moxifloxacin -> 2ed+ extended coverage of atypicals + G+ve
4th-> trovafloxacin -> 3ed + anaerobic coverage (withdrawn due to liver toxicity)
What is the pharmacokinetics of fluroquinolone?
- Well absorbed orally almost equal to intervenous administration
- The absorption impaired by divalent cations ( Mg, Ca, AL )
-Adjustments required in patient with creatinine clearance <50 - Limited CSF penetration
Clinical use for fluoroquinolone
1-urinary track infection (G-ve bacteria)
2-travelers’ diarrhea —>ciprofloxacin
3-tuberculosis
4-prostatitis
5-anthrax
6- Respiratory infection caused by pseudomonas aeruginosa (cystic fibrosis ,otitis)
Adverse effects of fluoroquinolone
1-Generally considered safe
2-GIT —> nausea, vomiting, diarrhea
3-CNS —>confusion, insomnia, dizziness, anxiety, seizures
4-CVS—> arrhythmia
5-Damage growing cartilage and bone
6-Phototoxicity (avoid excessive sun exposure)
7-Hypoglycemia (levofloxacin)
Contraindication of fluroqoinolone
Children -18
Pregnancy
Lactation
Epilepsy
Arrhythmia
—Drug drug interaction between ciprofloxacin and theophylline (through inhibition of CYP 450 metabolizing enzyme)
Classification of macrolides
Narrow spectrum
erythromycin
Broad spectrum
Clarithromycin
Roxithromycin
Azithromycin
What is the mechanism of action of macrolide?
Bacteriostatic agent that inhibits protein synthesis by binding to the 50 S ribosomal subunit
Macrolide work against what kind of bacteria?
Gram-positive and gram-negative bacteria
Therapeutic uses for macrolide
Staphylococcal infection
Streptococcal infection
Helicobacter pylori infection
Chlamydial infection
- diphtheria
- Syphilis
- Mycoplasma pneumonia
Pharmacokinetics of macrolide
—Erythromycin base is destroyed by stomach acid, so it must be administrated with enteric coating —
Food interferes with absorption (the broad-spectrum macrolides are fairly acid resistance)
Distribution : erythromycin are widely distributed in the body
Adverse effects of macrolides
- Hypersensitivity ( fever, skin rash)
- Gastrointestinal effect ( nausea, vomiting, diarrhea )
- Hepatitis with cholestatic jaundice
Macrolides are excreted through
Azithromycin and erythromycin are excreted through bile
Clarithromycin through kidney
Under what category of pregnancy drug is the macrolides?
Erythromycin and Azimyocin are category B
Clarithromycin is category C
