Antimicrobials 2 Flashcards
Whats is penicillin V a derivative off?
and when can it be used?
Benzylpenicillin
used in infectious mononucleosis - when amoxicillin can’t be used
Erysipelas is a skin infection that causes a nasty rash and is associated with S. pyogenes, what would be first line treatment?
Benzylpenicillin
What does tazocin cover that co-amoxiclav doesn’t?
Pseudomonas
Those with penicillin allergy can be given what other beta lactamase?
and what is the exception to the allergic reaction?
Aztreonam
- monobactam
If they had anaphylactic reaction they can’t be given them
Can vancomycin be stored at room temperature?
Yes - its extremely stable
What are the two main side effects of vancomycin? and what is the major clinical problem with it?
Nephrotoxicity
Red man syndrome
Clinically - underdosing
How does rifampin work?
when is it used?
what interaction can it have with certain drugs?
RNA polymerase
TB
P450 enzyme inducer - increases activity of it
How does Sulfamethoxazole work? and what category of antibiotics does it fall under?
Dihydropteroate Synthase
Folate inhibitors
What are common side effects of macrolides?
what drug are they contraindicated in?
D&V
Prolonged QT
- simvastatin
- reduced P450 enzymes
In the presence of a gram positive toxic producing disease, what antibiotic should be added?
Clindamycin
due to its excellent toxin producing inhibitory effects.
Whats the main antibiotics associated with C.Diff infection?
Co-amoxiclav
Cephalosporin
Ciprofloxacin (all quinolones)
Clindamycin
In upper non complicated UTI infections - which antibiotics should be used?
Ciprofloxacin
What are some common side effects of quinolones?
QT interval increase
Tendon rupture
Gastrointestinal upset
- can cause C. Diff
What organisms are ciprofloxacin very good against?
Gram negative
Atypicals
- hence their use in UTIs
Name the only bacteriostatic antibiotic used in TB treatment:
Ethambutol
List the antibiotics used in TB, and their mechanism of action and side effects:
Isoniazid
- bacterial cidal against fast growing organisms - stops mycolic acid production
- hepato and neural toxicity
- *6 months
Rifampin
- Bacterial cidal against slow growing in nectroci material - RNA polymerase inhibitor
- liver, bone marrow toxicity
- *6 months
Pyrazinamide
- bacterial cidal against mycobacterium intracellularly
- liver toxicity
- *2 months
Ethambutol
- Bacteriostatic - slow growing mycobacterium
- optic neuritis - colour vision loss
- 2 months
What antibiotic is used in Pneumocystis Jervico?
Co-trimoxazole
- sulfamethoxazole combination.
associated with Steven-johnson syndrome
How does metronidazole work?
what bacteria is it good against and what specific one is it not?
induces free radicals
Anaerobic bacteria
Actinomyces - it has no effect against.
What is first line treatment for UTIs and when is it contraindicated?
Trimethoprim
- 1st trimester of pregnancy
What is the pathway for UTI management:
No treatment - SNAIDs
Uncomplicated/ no pregnancy: Trimethoprim
Complicated UTI/ Pregnant: Ciprofloxacin
Severe UTI: Amoxicillin + gentamicin
Which antibiotics are not considered safe during pregnancy?
Trimethoprim - 1st trimester
Tetracyclines
Nitrofurantoin - 3rd trimester - haemolytic anaemia
Aminoglycosides
- Ototoxicity
Quinolones
- bone and joint abnormalities
Give an example of an inherently resistant antibiotic to a microorganism:
Vancomycin to Gram negatives - simply unable to uptake the drug
There is vertical and horizontal transmission of genetic information: what are they? and which is the most important towards resistance?
Vertical is from parent cell to progeny
Horizontal is the transferring of DNA information via other routes other than traditional parent to progeny.
Horizontal is most important towards the development of resistance.
Why are double regimes sometimes given to bacterial infections which are known to have mutations?
If resistance develops to one - the other will kill it prior to it being able to spread its resistance genes to progeny - i.e. vertical transmission
What the most important mode of horizontal transmission between bacteria, what is transferred, and what bacteria commonly do this?
Conjugation
Plasmids
Gram negative
Outline some facts about plasmids and common genes they encode for resistance:
Can be free within the bacteria or incoperated into the DNA.
most important for horizontal transfer of resistance.
frequently code for lactamases and efflux pumps
Where is MecA found and how does it lead to MRSA?
Found in the DNA chromosomes
causes resistance by encoding a mutated form of penicillin binding protein - preventing beta lactamases from working
MecA is encoded on cassettes of genes, which can vary in sizes - which sizes would you expect to find where?
Small cassettes - community
Larger cassettes - hospital
When taking a MRSA swap - where do you do it?
Nose
Perineum
In beta lactamase inhibitors - what are the parts that bind to the beta lactamases, preventing their function?
Tazobactam
Clavulanic acid
The genes for extended spectrum beta lactamases are often found where?
On plasmids
What is a gene that codes for carbpenamases?
What is another mode which some bacteria have become resistant to carbapenems?
NDM-1
Loss of porins
What pathogen can upregulate its efflux pumps in times of stress - such as having antibiotics present?
Pseudomonas aeruginosa
List some ways that anti-microbial resistance can be reduced through prescribing:
Narrow spectrum use - more targeted
Using older antibiotics - we have fewer new ones
Shorter periods of use.
Good infection control
Which bacteria frequently produce resistance through the production of beta lactamase production?
Coliforms
List some appropriate antimicrobial prescribing steps:
Establish diagnosis and severity prior to prescribing
microbiology samples
- before prescribing
Document indication for use
Document duration
Check penicillin allergies
Check for known resistance
- MRSA
Contact microbiology
Check specific for patients
What are Integrons?
These are Cassettes of resistant genes that are organised into genetic elements. They have the ability to increase (integrate) and remove these genes.
this ability makes them important for the spread of resistance
Name the most common genetic mutation leading to vancomycin resistance:
VanA
- plasmid
- chromosomal
Define septic Shock:
A subset of sepsis where there is profound circulatory, metabolic and cellular deterioration
with Hypotension with <65mmHg MAP despite vasopressors
with a lactate of >18mg/L
