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Year 1 Locomotion > Antibiotics MOA > Flashcards

Antibiotics MOA Flashcards

(40 cards)

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1
Q

Define Infection

A

invasion & multiplication of pathogenic microbes

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2
Q

Define Antibiotic

A

= anti-bacterial medication (not including disinfectants)

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3
Q

Define anti-bacterial

A

kills or inhibits growth of bacteria

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4
Q

Define broad spectrum

A

active against many bacteria (may kill normal flora)

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5
Q

Define narrow spectrum

A

active against few bacteria (may not kill all pathogens

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6
Q

Define Bactericidal

A

kills bacteria (by affecting bacterial cell wall)

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7
Q

Define bacteriostatic

A

inhibits growth of bacteria (by affecting RNA & DNA)

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8
Q

What is MINIMUM BACTERICIDAL CONCENTRATION (MBC)

A

lowest concentration that kills 99.9% of a population

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9
Q

what is Minimum inhibitory concentration (MIC)

A

lowest concentration which inhibits visible growth of bacteria

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10
Q

what is Breakpoint

A

MIC cut-off which separates strains where there is a high likelihood of treatment succeeding from those where treatment is more likely to fail

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11
Q

Describe Bacteria

size?

DNA?

metabolism?

cell wall?

A

Bacteria : 1 – 10 μm in size

DNA as a single chromosome (prokaryotes)

Independent metabolism & no organelles

Cell wall (different from cell membranes of host organism)

Peptidoglycan cell wall = Gram stain +ve

Lipopolysaccharide cell wall = Gram stain -ve

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12
Q

How are bacteria classified?

A

Bacteria are classified based on Gram staining & shape

  • Gram = positive or negative
  • Shape = coccus or bacillus/rod
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13
Q

Name examples of Gram positive cocci

A

Staphylococcus species, Streptococcus species

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14
Q

Name examples of Gram positive bacilli

A

Bacillus anthracis, Lactobacilli species

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15
Q

Name examples of gram negative cocci

A

Neisseria meningitidis, Haemophilus influenzae

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16
Q

name examples of Gram negative bacilli

A

Escherichia coli, Salmonella species

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17
Q

What are the potential targets of antibiotics?

Study These Flashcards
A
  • Bacterial cell wall
  • Bacterial RNA & protein synthesis
  • Bacterial DNA structure & function
  • Folic acid synthesis
18
Q

Which type of antibiotics target the bacterial cell wall?

Study These Flashcards
A

usually bactericidal

Beta-lactams (penicillins, cephalosporins & carbapenems)

Glycopeptides

19
Q

Which type of antibiotic targets Bacterial RNA & protein synthesis?

Study These Flashcards
A

usually bacteriostatic

Macrolides

Lincosamides

Tetracyclines

Aminoglycosides

20
Q

Which type of antibiotic targets Bacterial DNA structure & function

Study These Flashcards
A

bactericidal if high dose

Quinolones

Nitroimidazoles

Nitrofurantoin

21
Q

Which type of antbiotic targets Folic acid synthesis (required for DNA synthesis)

Study These Flashcards
A

usually bacteriostatic

Trimethoprim

Sulphonamides

22
Q

Describe Beta-Lactams (Penicilins)

What is their target?

Study These Flashcards
A

Penicillins :

Target : bacterial cell wall (bactericidal) - cell lysis by blocking cell wall synthesis

Penicillin (original & sometimes still the best) eg. tonsillitis

Amoxicillin (enhanced uptake by bacteria) eg. LRTI

Flucloxacillin (penicillinase-resistant) eg. SSTI

Co-amoxiclav (beta-lactamase inhibitor) eg. mixed infections

Benzylpenicillin

Piperacillin-tazobactam (anti-pseudomonal) eg. complex LRTI

23
Q

Describe Beta-Lactams (Cephalosporins)

What is their target?

Study These Flashcards
A

Target = Bacterial cell wall (bactericidal)

Ceftriaxone = 4th generation

Later generations have ↑ spectrum of activity

but also kill more natural flora (& ↓ efficacy against Gram +ves)

Used in bacterial meningitis & orthopaedic infections (ceftriaxone)

24
Q

What is the target of Beta-Lactams - Carbapenems

Study These Flashcards
A

Target : bacterial cell wall (bactericidal)

Examples : meropenem, ertapenem

Uses : infections in ITUs, complex & multi-drug resistant UTIs

25
What is the target of macrolides?
Target : RNA & bacterial protein synthesis (bacteriostatic) Examples : **erythromycin**, clarithromycin, azithromycin Uses : URTI, LRTI, SSTI (in place of penicillins) Atypical LRTIs (intracellular organisms)
26
What is the target of Lincosamides?
Target : RNA & bacterial protein synthesis (bacteriostatic) Example : **clindamycin** Uses : SSTI (in place of penicillins or when IV access is limited) Note : excellent bioavailability & tissue penetration when taken orally
27
What is the target for Tetracyclines?
Target : RNA & bacterial protein synthesis (bacteriostatic) Example : **doxycycline, Tetracycline** Uses : “atypical” bacteria that lack usual cell wall eg. Chlamydia, Mycoplasma Rickettsia infections eg. typhus
28
What is the target of Aminoglycosides?
Target : RNA & bacterial protein synthesis (bactericidal if high dose) Example : gentamicin Uses : severe Gram –ve infections synergistic treatment for endocarditis Note : renal toxicity & need for therapeutic drug monitoring limits use
29
What is the target for Quinolones? Examples? Uses?
Target : bacterial DNA structure & function (bactericidal if high dose) Examples : ciprofloxacin, levofloxacin Uses : Gram –ve infections (excluding anerobes) MRSA infections LRTIs (levofloxacin only) Note : also associated with CDAD
30
What is the target for Nitroimidazoles? Example? Uses?
Target : bacterial DNA structure & function (bactericidal if high dose) Example : metronidazole Uses : anaerobic infections (abscesses)
31
What is the target for Ntrofurantoin? Uses?
Target : bacterial DNA synthesis (bactericidal if high dose) Uses : uncomplicated UTIs Note : poor bioavailability, but is concentrated in urine
32
What is the target for anti-folates? Example? Uses?
Target : folic acid synthesis & so DNA synthesis (bacteriostatic) Examples : trimethoprim, sulphonamides Uses : uncomplicated UTIs (but not in pregnant women)
33
What do you need to consider when choosing an antibiotic?
* Sepsis & supportive treatments * Use the diagnostic process * Microbiology tests * Consider antibiotic guidelines
34
What is the Sepsis 6 care bundle?
1. Give high-flow oxygen 2. Take blood cultures 3. Give empirical IV antibiotics 4. Measure FBC & serum lactate 5. Start IV fluid resuscitation 6. Start accurate urine output measurements
35
Briefly outline the diagnostic process?
History = PC, HPC, PMH, ADT, FH, SH, ROS ↓ Examination = General, CVS, RS, ABDO, NS, LMS etc. ↓ Differential Diagnosis ↓ Investigations = (bedside), body fluids, imaging, physiology, histopathology ↓ Diagnosis ↓ Treatment
36
What microiology samples would you request?
Samples : Swabs = pus, skin, nose, throat, urethra, vagina etc. Body fluids = pus, urine, faeces, blood, CSF etc. Body tissues = biopsies (rarely)
37
What microbiology investigations would you request?
Can be divided into direct & indirect techniques … Direct : * Microscopy, culture & sensitivity (usually refers to bacteria or fungi) * Antigen detection tests (eg. malaria, Legionella, C. difficile toxin) * PCR tests (eg. Mycobacteria, 16S Ribosomal DNA) Indirect : • Serology tests (eg. rare or neglected tropical infections)
38
Name some factors affecting antiobiotic choice relating to the organism
* Known organism +/- sensitivities & resistance profile * Or the most likely organisms and their sensitivities/resistance
39
Name some factors affecting antiobiotic choice relating to the patient
* Allergy/Intolerance * Renal & liver function * Severity of infection/Is patient immunocompromised? * Risk of antibiotic-associated infection * Route of administration * Interactions with other medication * age/ethnic group * Pregnant, breast feeding or taking oral contraception
40
Why do we need antibiotic guidelines?
* To produce effective and efficient treatment * To reduce over-pescribing and use of broad spectrum antibiotics which can lead to antibiotic resistance and other complicatons

Year 1 Locomotion (18 decks)

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