4. Antibiotics And Antimicrobials Flashcards

Question

Mutation Genetic mechanisms of resistance

Answer 1

• base changes or deletions lead to altered targets of antibiotic action

Answer 2

• Disc sensitivity testing Antibiotic sensitivity by Etest Automated antibiotic sensitivity testing

Answer 3

○ Sensitive ○ Intermediate = few bacteria grow ○ Resistant = nothing happens around zone bacteria still grow Look at zones of inhibition to find most effective antibiotic • Know which antibiotic is the most important

Answer 4

• Minimum inhibitory concetration MIC as mg/L ○ Minimum concentration of that antibiotic that inhibits bacterial growth * Strip with different concentrations of antibiotics * Minimum inhibitory concentration is where zone of bacteria stops

Answer 5

• Much faster • Minimum inhibitory concetration MIC as mg/L ○ Minimum concentration of that antibiotic that inhibits bacterial growth

Answer 6

* when to use antibiotic depends on Severity /cause of infection * Consider patient’s medical history, other drugs and allergy to antibiotics (e.g. allergy to penicillin) * Taking samples (eg swab, blood, urine sample, tissue or bone sample) before start of antibiotic therapy * Broad spectrum antibiotics should be used if there is an urgency and the causative organism has not been identified * Route of administration * Dose of antibiotics * Combination therapy = 2 antibiotics at a time * Longevity of therapy * Prophylaxis = problem with heart valves, heart valves can be very prone to infection

Answer 7

* Penicillins * Cephalosporins * Carbapenems * Monobactams

Answer 8

• mainly active against streptococci

Answer 9

Penicillin Amoxicillin Flucloxacillin

Answer 10

* also some activity against Gram-negatives | * Broad spectrum

Answer 11

• active against staphylococci & streptococci

Answer 12

* amoxicillin/clavulanate (all of above +anaerobes + Gram negative bacteria) * piperacillin/tazobactam (as above + Gram negative, including Pseudomonas species

Answer 13

Broad-spectrum but no anaerobe activity – don't act on anaerobic bacteria (e.g. clostridium) * Cetriaxone has good activity in the CSF * Concern over association with C. difficile major side effect of this drug is c.difficile infection * Ceftazidime + avibactam and ceftolozane + tazobactam used for multidrug resistant Gram negative infections

Answer 14

→ safe if allergic to penicillin ``` • Imipenem • meropenem • ertapenem – very broad spectrum (incl anaerobes) – active against most (not all) Gram negatives – generally safe in penicillin allergy ``` • imipenem + relebactam – serious Gram negative infections (including anaerobes) • meropenem + vaborbactam – complicated Gram negative UTI

Answer 15

---> interfere with cell wall synthesis Vancomycin Teicoplanin Dalbavancin and telavancin

Answer 16

– active against most Gram positive (not Gram negative) – some enterococci resistant (VRE) – resistance in staphs rare – not absorbed (oral for C. difficile only as it acts locally), normally given intravenously for other infections – therapeutic drug monitoring (TDM) required (narrow therapeutic window)

Answer 17

Tetracycline & doxycycline – similar spectrum, both oral only – broad-spectrum but specific use in penicillin allergy, usually for Gram positive – active in atypical pathogens in pneumonia – active against chlamydia & some protozoa – should not be given to children <12 years = as it affects mineralising tissue

Answer 18

Most common agent is gentamicin = can be quite toxic * Profound activity against Gram negative * Good activity in the blood/urine * Potentially nephrotoxic/ototoxic * Therapeutic drug monitoring (TDM) required * Generally reserved for severe Gram negative sepsis

Answer 19

e.g. erythromycin (& clarithromycin) • Well distributed including intracellular penetration • Alternative to penicillin for mild Gram positive infections • Also active against atypical respiratory pathogens

Answer 20

• Azoles (active against yeasts +/- molds – inhibit cell-membrane synthesis – fluconazole used to treat Candida • Itra/vori/posaconazole also active against Aspergillus • Polyenes (nystatin and amphotericin) – inhibit cell membrane function – nystatin for topical treatment of Candida – amphotericin for IV treatment of systemic fungal infections (e.g. Aspergillus) Fungal infections = very severe in immunocompromised patients

Answer 21

• Active against anaerobic bacteria • Also active against protozoa: – Amoebae (dysentery & systemic) – Giardia (diarrhoea) – Trichomonas (vaginitis)

Answer 22

• Aciclovir – when phosphorylated inhibits viral DNA polymerase = inhibit DNA viruses – Herpes simplex – genital herpes, encephalitis – Varicella zoster – chicken pox & shingles • Oseltamivir (‘Tamiflu’) – inhibits viral neuraminidase = stops virus from leaving the cell – influenza A & B • Specialist agents for HIV, HBV, HCV, CMV

Answer 23

→ through natural selection 1. Genetic mechanisms confer drug resistance due to mutations and genetic variation 2. Antibiotics kill non-resistant bacteria 3. Drug resistant bacteria selected and reproduce due to competitive advantage (less competition for food and space etc) 4. Drug resistance gene transmitted through (exposure naïve) population

Answer 24

MDR (multi-drug resistant) XDR (extensively drug resistant) PDR (pan-drug resistant)

Answer 25

Non-susceptibility to at least one agent in three or more antimicrobial categories

Answer 26

• Non-susceptibility to at least one agent in all but two or fewer antimicrobial categories

Answer 27

* Non-susceptibility to all agents in all antimicrobial categories * Smallest populations of bacteria

Answer 28

As prescribing and use increases so does resistance

Answer 29

Laboratory evidence Ecological studies Individual level data

Answer 30

* Provides biological plausibility | * Colonies growing on agar plates – see antibiotics working

Answer 31

* Relates levels of antibacterial use in a population with levels of resistance * Patterns of resistance and prescribing

Answer 32

• Relates prior antibacterial use in an individual with the subsequent presence of bacterial resistance (detected by culture or molecular means)

Answer 33

* Get a lot of money for making medications for chronic conditions * Not much money to be made in antibiotics * Hard to make antibiotics from scratch as we don't have enough understanding

Answer 34

Commitment to always use antibiotics appropriately and safe Only when they are needed Choose right antibiotics and administer them in the right way

Answer 35

• Relief of symptoms ○ They think the antibiotics might work, better than just leaving the infection • Worry about complications/more serious illness ○ Worried that leaving it untreated may lead to something more serious • Patient pressure ○ what the patient wants, we want to be liked by patients

Answer 36

Coordinated interventions designed to improve and measure the appropriate use of antimicrobials by promoting the selection of the optimal antimicrobial drug regimen, dose, duration of therapy, and route of administration. Antimicrobial stewards seek to achieve optimal clinical outcomes related to antimicrobial use, minimize toxicity and other adverse events, reduce the costs of health care for infections, and limit the selection for antimicrobial resistant strains

Answer 37

---> if antibiotics are given appropriately, duration of infection can be reduced • The antibitoics do relieve symptoms but patients need to understand if the antibiotics will actually be benefical for them NNT – number needed to treat • NNT for an adverse effect is always lower than the NNT for one additional benefit to patient • If you take na antibiotic and give it to patient= you are more likely to harm them than improve them if the antibiotic is given inappropriately

Answer 38

• MDT Surveillance Interventions

Answer 39

Effective collaboration across multidisciplinary team in implementing antimicrobial stewardship

Answer 40

– Process measures • Antibacterial use (quantity, type, appropriateness) • Benchmarking within and between organisations – Outcome measures • Patient • Emergence of resistant organisms

Answer 41

– Persuasive = people, opinions, advice – Restrictive = rules and regulations – Structural = • Computerised records, Rapid lab tests, Expert systems,Quality monitoring

Answer 42

Infection of deep dermis Streptococcus pyogenes Staphylococcus aureus

Answer 43

Prp recognise pamps

Answer 44

Nsaid Pain relief Elevation and immobilisation of leg Saline dressings

Answer 45

Vancomyosin flucloxacilin Doxycilin

Answer 46

Difficulty, pain , discomfort passing urine