Antimicrobials Flashcards
Define a microbe
a microscopic organism which could have the potential to cause harm
Why do we use antimicrobial chemotherapy?
sytemic
loca infections
What are the other reasons for administering antimicrobals
Prophylaxis
Surgery / travel
Gut motility
Farming
How can you tell between gram+ and gram- bacteria in a laboratory?
gram- stain violet/purple
gram+ stain red
this is because gram+ have a thinner wall
Structure wise what is the difference between gram+ and gram- bacteria?
gram + bacteria have a thinner wall
Which type of bacteria is ore harmful and why?
Gram- bacteria are more pathogenic than gram+ because they produce harmful endotoxins.
What type of antibiotics are there?
bacteriostatic
bacteriocidal
How do bacteriocidal antibiotics work?
They kill bacteria by destroying the cell wall structure, allowig water to enter and causing the cell to lyse
How do bacteriostatic antibiotics work?
stop cell replication by inhibiting protein and nucleic acid synthesis.
What type of antibiotic kills bacteria?
bacteriocidal
What type of antibiotic stops baterial cell replication?
bacteriostatic
What general considerations should be taken into account prior to a prescribing antibiotics?
Know the patient:- Sensitivities / Allergies Renal / hepatic function Resistance to infection Severity of illness Ethnicity Tolerance of oral dosage Pregnancy / breast feeding
Why should ethnicity be taken into account prior to prescribing an antibiotic
some ethnic backgrounds may be more resitant toa particular antibiotic
What is inherent resistance?
particular gram stains are resistance to antibiotics due to there cell wall structure
What is acquired resistance?
induced resistance of a bacteria to an antibiotic it was originally sensitive to, (i.e. concentration need would have to be toxic)
What type of antibiotic resistance is a result of the wall structure of the bacteria?
inherent resistance
What type of antibiotic resistance is a result of continuous use of antibiotics causing mutations in bacteria?
acquired resistance
Which is better: amoxicillin or augmentin?
in the eyes of Dr Ehsan
Augmentin
Why is MRSA resistant to penecillin?
MRSA possess enzyme known as beta-lactamase that destroys the compound
What factors are considered when choosing an antibiotic for a patient?
Patient
- Allergies
- renal & hepatic function
- susceptibility
- age
- severity of illness
- pregnancy
- breastfeeding
- tolerate oral drugs?
Organism
- Local bugs
- multi-drug resistance (MDR)
Culture and sensitivity when possible – why?
PO or IV
Why might a patient be prescribed multiple antibiotics?
To prevent the emergence of resistant strains
To treat mixed infections
To treat emergency / life threatening cases before a firm diagnosis
To take advantage of antibiotic synergism
To use lower doses of a toxic drug
What are some o the general side effects of antibiotics?
Elimination of commensals
Continuous Antibiotic use destroys gut flora - Diarrhoea - Reduced absorption - of nutrients - Anaemia due to abnormal absorption of vitamin B12
Allergic reactions / Anaphylaxis
Toxicity
renal / hepatic
What nursing responsibilities to the patient who is taking antibiotics?
Inappropriate dosage or incomplete courses lead to antibiotic resistance.
Patients frequently feel better after 2-3 days of antibiotics and stop taking them, especially if GI tract disturbance occurs
!!!Ensure that patient takes complete course of antibiotic
If antibiotic is causing considerable distress to the patient then it needs to be changed for another antibiotic
Why is it important to take bloods prior and throughout the administration of antibiotcs?
narrow therapeutic index
Peak / trough level of antibiotic (therapeutic drug monitoring: TDM).
Efficacy of antibiotic may be time dependent, concentration dependent and T&C dependent
Minimum inhibitory concentration (MIC) affected by many things:
Renal function
Hepatic function
Changes in compartment volumes
what drug interactions must be considered prior to antibiotic administration?
Addition of an antibiotic may influence other drug levels
Antacids and laxatives contain metals like
aluminium, calcium and magnesium which
tend to bind (chelate) antibiotics in the GI
tract.
This reduces absorption of many
antibiotics, eg Ciprofloxacin, Tetracyclines
How can microbial resistance have global effects?
Giving antibiotics to an individual can affect more than just that individual
One bacterium that develops resistance can pass the genes for this into many others, and other species
The total antibiotic resistance gene pool for all bacteria world wide can be viewed as the ‘resistome’
What is Teixobactic?
an antibiotic Identified 2015
•Effective against gram positive microbes
- Inhibits formation of type II lipids involved in the petidoglycan production
- More resistant to mutation as it acts on lipids rather than proteins.
•4-5 years until introduction into clinical practice?
Currently effective against MRSA, VRE and TB (in the lab
What factors promote the transmission of MDR bacteria?
Patient transfer
Internal and external (notes, bedding)
Open Nursing
cross contamination of neighbouring pt
Non-compliance to staff hygiene protocols: - Inadequate washing of hands - Inadequate apron and glove usage White coats , Ties
Define adverse reactions
Unwanted effects sometimes occur unrelated to the basic pharmacological action of a drug but rather as a result of its direct action: .g. – gastric bleeding from aspirin.
Adverse reactions unrelated to the main action of a drug are often caused by:- reactive metabolites and/or immunological reactions.
Usually such unwanted effects are reversible by reducing the dose or changing the prescription.
Define side effects
‘Those responses not required clinically which occur at doses of the drug within the therapeutic range’
What are the main risk factors of adverses drug effects?
Older age
Polypharmacy
comorbidities
Female gender
Poor literacy
What are the types of adverse drug reactions you need to know for the exam?
Type A and Type B
What is a Type A reaction?
Adverse reactions included in this category are usually dose dependent
An example of a Type A response is the respiratory depression that occurs with the administration of fentanyl - this may be viewed as a predictable and dose dependent reaction
What is a type b reaction?
They cannot be predicted from the known pharmacology of the drug
Dose dependency is usually not a feature
These reactions often have uncertain mechanisms
These are common and mortality is often high
Examples include hepatotoxiticity, blood dyscrasias
How does the kidney function of neonates affeect the half life of a drug
prolongs drug half-life
What is a compliment cascade?
complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen’s cell membrane.
How does ageing affect absorption
Decreased gastric acid secretion
Altered gastrointestinal peristalsis
Reduces oral drug absorption
How does ageing affect distribultio of drugs in the body?
Total body water decrease and total body fat increase.
Distribution of fat-soluble drugs e.g. diazepam and water-soluble drugs such as digoxin, changes
How does ageing affect plasma protein binding in the body?
Decreased plasma albumin restricts drug binding,
Produces higher free concentrations of albumin bound drugs (e.g. warfarin).
How does ageing affect metabolism of drugs?
Reduced hepatic blood flow; slower metabolism
Alters half life, may result in increased absorption, e.g. barbiturates such as thiopentone sodium.
Less first pass effect
How does ageing affect renal excretion of drugs?
Glomerular filtration rate is decreased by 30% by the age of 65.
The lower filtration rate, reduces excretion
Increasing half life e.g. digoxin
What two levels are indication of kidney funcion in blood test?
craetinine and urea
How does ageing affect creatinine?
older people have less muscle mass
Older people have lower normal creatinine levels, thus they may have renal impairment even with ‘normal creatinine levels
