Flashcards in Microbiology Antibiotics 1 Deck (39):
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Beta Lactams type
1. Penicillins
2. Cephalosporins
3. Carbapenems
4. Monobactams
5. Blactamase inhibitors
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Penicillin → Discovery
Alexander flemming 1929 used finally in 1940
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Penicillin → Resistance via
Enzymatic digestion of Beta Lactam ring or target site modification (MRSA) – bacteria change confirmation of enzymes and so B lactams canit bind
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Penicillin →Absorption
Oral: Poor oral absorption
IV
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Penicillin →Distribution
Body water about 0.2 L/Kg
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Penicillin →Metabolism
Peak concentration in 1-2h
Little metabolism
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Penicillin →Excretion
Mainly urinary excretion
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Penicillin →Side effects
Generally mild
• Allergy important as is assessment of allergy (analphylactive reactions)
• GI upset especially C.difficile in hospital with broad-spectrum agents.
• Hepatic
• Platelet
• CNS – convulsion
• Platelet abnormalities
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Penicillin →Indications: Penicillin V/G
B. haemolytic streptococci
Pneumococci
Meningococci
Gonococci (not susceptible anymore)
Anaerobes GPAC and clostridia (gas gangrene)
NB resistance in pneumococci
Gonococci
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Penicillin →Indications for flucloxacillin
S.aureus (NB resistance MRSA)
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Penicillin → Indiciation sfor Ampicillin/amoxicillin + clavunate (inhibitor)
Otitis media
COPD exacerbation
CAP
UTI
Skin and soft tissue infection
Surgical prophylaxis
Intra abdominal surgery
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Penicillin → Piperacillin/tazobactam
Hospital IV therapy 2nd line
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Penicillin →Broad spectrum example
Ampicillin/amoxicillin
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Penicillin →Blactam/Blactamase inhiitors example
Co-amoxiclav (amoxicillin-clavulante)
Piperacillin – tazobactam
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Penicillin →Inhibitor action
Prevent Beta lactamase action so by introducing an inhibitor it can block the enzyme produced y the bacteria aimed to breakdown the antibiotic and so this allows the antibiotic to act.
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Carbapenems: Example
Meropenem
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Carbapenems: Specification
Very broad spectrum
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Carbapenems: Absorption
Injectable only
Used as 2nd/3rd line therapy in hospital
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Carbapenems:Action
Typical Blactam pharmacokinetics
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Carbapenems:Resistance
Remains rare
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Carbapenems:Not active against
MRSA
Stenotrophomonas
Maltophilia
Some enterococci
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Cephalosporins: Isolated from
Fungus cephalosporium acremonium in Sardinia
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Cephalosporins: Classified based on
Generations on chronology and antimicrobial spectrum.
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Cephalosporins:First generation example
Cephalexin
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Cephalosporins: Second generation example
Cefuroxime
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Cephalosporins: Third generation example
Cefotaime, ceftriaxone, ceftazidime
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Cephalosporins: Fourth generation example
Cefpirome
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Cephalosporins:Bacterial always resistant are:
• MRSA
• Enterococci
• Listeria
• Legionella – no cell wall therefore beta lactams don’t work therefor combine with macrolides
• C. difficile
• Campylobacter
• ESBL producing E.coli, Klebsiella
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Cephalosporins: Indiciations
• Acute meningitis (cefotaxime/ceftriaxone)
• Surgical prophylaxis (abdominal, orthopaedic, head and neck, obstetrical)
• UTI/acute pyelonephritis
• Chest infection
• CA sepsis of unknown site: ceftriazxone
• Hospital acquired sepsos unknow site: ceftazidine + 2nd agent
• Skin/soft tissue infection
• Intra abdominal infection + metronidazole
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First generation: Cephalosporins: Active against
Gram positive cocci (Streptococci and Staphylococci) and Gram negatives
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First generation: Cephalosporins: Used for
UTI (E.coli, Klebsiella, Proteus spp)
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First generation: Cephalosporins: Absorption
Oral
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First generation: Cephalosporins: Commonly used in
GP
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Second generation: Cephalosporins: Active against
Gram positive cocci (Streptococci and Staphylococci)
Gram negatives which cause CAP and exacerbation COPD (H. influenza, M. catarrhalis)
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Second generation: Cephalosporins: Absorption
Mainly IV
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Third Generation: Cephalosporins: Active against
Hospital gram negative rods
Poor against gram positive
• Citrobacter
• Serratia for ceftriaxone/cefotaxime
• Pseudomonas aeruginosa for ceftazidime
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Third Generation:Cephalosporins: Absorption
Mainly IV
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Fourth Generation: Cephalosporins: active for
Similar spectrum to ceftazidime but also good activity against some gram positive cocci.
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