antimicrobial Flashcards
narrow spectrum
active against Gram-positive or Gram-negative, aerobic or anaerobic bacteria
eg of narrow spectrum
Vancomycin, colistin, azteronam
Broad spectrum
active against Gram-positive and Gram-negative, aerobic and anaerobic)
eg of broad spectrum
Third generation cephalosporin, piperacillin
Extended spectrum
very wide range activity it may not cover small number of pathogens
eg of extended spectrum
Carbapenem, tigycycline
what drugs act on cell wall synthesis ?
cycloserine vancomycin bacitracin penicillin cephalosporin
what drugs act on dna gyrase?
nalidixic acid
quinolones
what drug act on dna dependent rna polymerase ?
rifampicin
what drugs act on protein synthesis by inhibiting 50s?
erythromycin
chloramphenicol
clindamycin
what drugs act on protein synthesis by inhibiting 30s?
tetracycline spectinomycin streptomycin gentamicin tobramycin amikacin
what drug acts on cell membrane ?
polymyxins
what drugs act on folic acid metabolism?
trimethoprim
sulfonamides
drugs Inhibit Cell wall synthesis how?
acting on formation of peptidoglycan
Inhibitors of bacterial cell wall synthesis
β-lactam act on the final stages of peptidoglycan synthesis
what are the β-lactams
penicillin
cephalosporin
carbapenem
monobactam
β-lactams characteristics
All share β-lactam ring
Principal target is Transpeptidase
All bound to penicillin binding proteins (PBP)
PBP are involved in cell wall construction ( Bactericidal)
penicillin structure
5-membered thiazolinering fused to β-lactam ring
first natural penicillin is produced by ?
penicillium
resistance to penicillin is a result of what?
enzymes = penicillinases
negatives of penicillin
Breakdown by gastric acidity (poorly absorbed by mouth)
Very rapid excretion by the kidney
Narrow spectrum
6-Aminopenicillanic acid (6-APA) is better than benzyl penicillin in terms of what?
Antibacterial activity ( broader spectrum)
Stability to bacterial β-lactamases
Pharmacokinetic properties ( better absorption)
group 1 penicillin aka
parenteral penicillin
what are the parenteral penicillins?
Benzyl penicillin
Procaine penicillin (long acting)
group 2 penicillin aka
Oral penicillin
what is a kind of Oral penicillin?
Penicillin V
Classifications of penicillin is on the basis of ….
antibacterial spectra
group 3 aka
Anti-staphylococcal penicillin
whats a kind of Anti-staphylococcal penicillin?
Cloxacillin
group 4 aka
Extended-spectrum penicillin
what are Extended-spectrum penicillin active against?
Enterobacteriacea except Pseudomonas
what are the kinds of Extended-spectrum penicillin?
Ampicillin
Amoxicillin
group 5 aka
penicillin active against Pseudomonas aeruginosa
what is an example of penicillin active against Pseudomonas aeruginosa?
Piperacillin
group 6 aka
β-lactamase-resistant penicillin
β-lactamase-resistant penicillin is active against what?
gram negative only
whats an example of β-lactamase-resistant penicillin?
Temocillin
what causes Hypersensitivity reaction Anaphylactic reaction ( rare, rapid reaction within minutes, nausea, vomiting , dyspnea and coma, fatal) as side effects?
penicillin
what causes Purities and urticarial reaction (develop within 1-3days )
Skin eruptions usually maculopapularrashes (commonest) as side effects?
penicillin
what causes Hemolytic anemia and thrombocytopenia
Neurotoxicity with high doses (rare) as side effects?
penicillin
cephalosporin structure
6-membered dihydrothiazinering fused to a β-lactam ring
cephalosporins are derivatives of ….
7-aminocephalosporanicacid (7-ACA)
Cephalosporin advantages over penicillin
More stable to enzymes ( Staphylococcus penicillinases)
Broader spectrum
Less prone to cause hypersensitivity
Oral and parenteral preparations
penicillin is better than cephalosporin in that…
more active against Enterococci
cephalosporin 1st gen
Cephalexin
Cephazolin
cephalosporin 2nd gen
Cefuroxime
Cefoxitin
cephalosporin 3rd gen
Cefotaxime
Ceftriaxone
Ceftazidime (antipseudomonal)
cephalosporin 4th gen
Cephepime
cephalosporin 1st gen active against
Wide range of Gram-positive and negative except (Pseudomonasand Haemophilus)
Streptococcus, Staphylococcus, Enterobacteriacae
cephalosporin 2nd gen active against
Wide range of Gram-positive and negative including Haemophilusand anaerobes
Cefuroxime: like cephalexin plus …
active against Haemophilusand S. pneumoniae
cephalosporin 3rd gen active against
Wide range but more anti-Gram-negative than second generation
Cefotaxime: active against
Enterobactericae, Haemophilusand S. pneumoniae and not active against Pseudomonasspp
cephalosporin 4th gen is
Anti-Gram-negative
cephepime
active against Enterobacteriacaeand Pseudomonas
what causes Local pain and thrombophlebitis at site of injection +
Hypersensitivity reaction in 0.5-10% of patients (10% cross reaction with penicillin allergy) as side effects?
cephalosporin
what causes Hepatotoxicity and Gastrointestinal disturbance as side effects?
cephalosporin
what causes Thrombocytopenia and Pseudomembranous colitis?
cephalosporin
Monobactams aka
Monocyclic β-lactam antibiotics
example of monobactam
Aztreonam
Aztreonam
Narrow spectrum (anti-Gram-negative aerobic bacilli)
Bactericidal
Stable to bacterial enzymes
what drug is isolated from Streptomyces’s?
Carbapenem
what drug has Potent activity against a broad range of Gram-positive and negative bacteria?
Carbapenem
what drug is Resistant to lysisby β-lactamases?
Carbapenem
what are 2 important carbapenems?
Imipenem
Meropenem
Imipenem char
Not stable, it need to be combined with cilastatinto be more stable
Safe
Broad spectrum
Seizures and transient changes in liver enzymes are main side effects
Meropenem
Stable and broad spectrum
Side effects .. Similar toimipenem
Glycopeptides
Vancomycin& Teicoplanin
Glycopeptides Mode of action
Act on cell wall synthesis at a stage prior to B-lactams
Not act on PBP & not inactivated by B-lactamases enzymes
what drug has these characteristics ?
Activity is restricted to Gram-positive bacteria only
Poorly absorbed from GI
IM injections are painful
Glycopeptides
what drug has these characteristics ?
Nephrotoxic Ototoxic
Reversible neutropenia and thrombocytopenia
Glycopeptides
_______ is less nephrotoxic than vancomycin
Teicoplanin
Glycopeptides Clinical use
MRSA
Patient allergic to penicillin or cephalosporin with Staphylococcus or Streptococcal infections
…… indirectly inhibit DNA synthesis
Sulphonamides& Trimethoprim
________ directly inhibit DNA-gyrase
Quinolones
________ bind to bacterial ribosome and inhibit protein synthesis
Nitrofurantoin
________ inhibit DNA dependent RNA polymerase
Rifampicin
true or false Sulphonamides& Trimethoprim act on same stages of folic acid synthesis
false
Sulphonamide inhibit ……. while man cell require performed vitamin ( basis of selective toxicity)
early stages of folic acid synthesis and bacteria cannot utilize exogenous source of the vitamin
Trimethoprime act on…… (selectively it has high affinity for bacterial enzymes)
later stages of folic acid synthesis by inhibiting dihydrofolate reductase
sulfonamide char
Broad spectrum of activity
Well absorbed after oral administration
some side effects of sulfonamide
Crystalluria and hematuria
Hypersensitivity (fever and rash) or urticarial rashes
Stevens-Johnson syndrome (rare but could be fatal)
what does sulfonamide cause in patients with G6PD deficiency?
hemolytic anemia
what drug causes Megaloblastic anemia and Liver damage as side effects?
sulfonamide
what drug is contraindicated in pregnancy because it interferes with bilirubin transfer in fetus?
sulfonamide
trimethoprim is active against what?
Gram-positive aerobic bacteria and Enterobactericaeae
what drug is rapidly absorbed from GI?
trimethoprim
whats the most commons side effect of trimethoprim?
olic acid deficiency may lead to megaloblasticanemia if used for long time
whats mainly used for uti in combo with sulfonamide
trimethoprim ( as cotrimoxazole)
Nitrofurantoin moa
Act on bacterial mRNA, ribosomal proteins
what is well absorbed orally?
Nitrofurantoin
what drug is used for uti?
Nitrofurantoin
side effects of Nitrofurantoin
Nausea and vomiting
Peripheral neuropathy
Hemolysis in patients with G6PDdeficiency
quinolones structure
dual ring
quinilones moa
inhibiting DNA gyrase (topoisomerase) this will inhibit DNA replication
4-quinolones
naladixicacid
Fluoroquinolones
Ciprofloxacin
Ciprofloxacin characteristics
More potent
Broader spectrum (UTI, Osteomyelitis, STD, Pneumonia)
Better absorption and distribution (oral & parenteral)
quinolones side effects
GI ( nausea, vomiting & diarrhea)
Pseudomembranous colitisSkin rash
CNS (benign intracranial hypertension) and psychosis
Thrombocytopenia
Metronidazole structure
5-nitroimidazole
Metronidazole moa
Exert its effect by reduction of the nitro group to amine under low redox potential
Metronidazole active against
obligate anaerobes & helicobacter and protozoa (T. vaginalis, Giardia, E. histlolytica)
what drug is rapidly and completely absorbed from GI?
Metronidazole
Metronidazole side effects
CNS, confusion and seizures
Peripheral neuropathyGI (nausea, vomiting & diarrhea)
Neutropenia (reversible)
Metallic taste
Rash and pruritis
what drug causes metallic taste
Metronidazole
what drug causes Pseudomembranous colitis?
quinolones