Introduction to infections PART 2 Flashcards
Define the term Cmax
This is the maximum concentration at which you must have your antibiotic so that it can achieve what you want it to do
Define the term MIC (minimum inhibitory concentration)
This is the minimum concentration of an antibiotic required in order to produce the desired effect.
What is a concentration dependent antibiotics?
You must have a peak concentration at the site of infection so that is can be effective. A high concentration in the blood is required. Concentration must be constantly above the MIC.
Post-antibiotic effect is still in play. Even if the concentration of antibiotic is below minimum inhibitory concentration there is still an antibiotic effect occurring: inhibiting microbial growth.
E.G., AMINOGLYCOSIDES
What is a time dependent antibiotic?
Concentration should be maintained above the MIC between doses. Higher doses do not increase antimicrobial activity. There is no post-antibiotic effect, there is no residual antibiotic effect after concentrations of antibiotics has fallen below the MIC.
E.G., BETA LACTAMS, MACROLIDES
What is a bacterial-static antibiotic?
This form of inhibitor is reversible stoppage. It arrests the bacteria.
What is a bacteriocidal antibiotic?
This form of inhibitor is irreversible. It kills the actual microbe.
What is Prophylaxis treatment? and how does that differ from normal treatment?
Prophylaxis is to prevent infectious complications (e.g, during surgery), or to prevent recurrent infection. Normally doses are given as STAT.
Normal treatment is to reduce the growth or reproduction of pathogens (e.g., infection or colonisation). These tend to be lower doses than prophylaxis doses, with differences in dosing regimens.
What is empirical therapy?
This is the initial ‘blind’ therapy, however not blind at all because it is based in evidence.
Empiric therapy or empirical therapy is medical treatment or therapy based on experience and, more specifically, therapy begun on the basis of a clinical “educated guess” in the absence of complete or perfect information. Antibiotics can be switched after MC+S results.
Urine collection: microscopy, culture and sensitivity (MCS)
What is drug monitoring?
Monitoring the response to a drug, the resolution of any signs and symptoms. We must always check renal and liver function and any patient allergies.
What are microbiological assays?
These enable testing. Used to determine the potency of a drug in animals or man and monitoring and controlling anti- microbial chemotherapy.
What is red man syndrome?
For Vancomycin, if it is given too fast it will cause red man syndrome. The patient will turn red because of the sensitivity.
What are the dangers of giving amino-glycosides too fast?
This may cause nephro-toxicity and ototoxicity.
Nephrotoxicity is defining as rapid deterioration in the kidney function due to toxic effect of medications and chemicals.
Ototoxicity is when a person develops hearing or balance problems due to a medicine.
What microorganisms most commonly cause urinary tract infections?
E.coli, Klebsiella, Proteus
What microorganisms most commonly cause skin infections?
e.g., cellulitis is caused by staphylococcus, streptococcus and MRSA
MRSA is a type of bacteria that’s resistant to several widely used antibiotics. This means infections with MRSA can be harder to treat than other bacterial infections. The full name of MRSA is methicillin-resistant Staphylococcus aureus. You might have heard it called a “superbug”.
What microorganisms most commonly cause respiratory infections?
URTI (An upper respiratory tract infection):
Group A & C Streptococcus, Mycoplasma, Haemophylis Influenza
LRTI (Lower Respiratory Tract Infections):
Pseudomonas, Strep pneumoniae, Legionella, Staf aureus, Haemophylis Influenza
What microorganisms most commonly cause Gastrointestinal Infection?
Norvirus, C difficile, Salmonella
Outline the key characteristics of beta-lactums, giving examples and highlighting their mechanism of action, indication and adverse effects.
E.g., penicillin, cephalosporin, carbapenem, monobactam
β-lactam antibiotics (beta-lactam antibiotics) are antibiotics that contain a beta-lactam ring in their chemical structure.
The mechanism of action is to inhibit the cell wall synthesis. We have beta lactamases that will inhibit the inhibitor of cell wall synthesis by attacking the beta lactum, causing resistance.
Co-amoxiclav contains amoxicillin (an antibiotic from the penicillin group of medicines) mixed with clavulanic acid. The clavulanic acid stops bacteria from breaking down amoxicillin, allowing the antibiotic to work better. This drug is often used a third or fourth line to prevent resistance from occurring.
A patient may have a penicillin allergy so they wouldn’t be able to be prescribed groups classed as beta-lactums. Most common side effects include diarrhoea and GI upset.
A patient should be converted from IV to oral formulations as soon as possible.
Outline the key characteristics of macrolides, giving examples and highlighting their mechanism of action, indication and adverse effects.
E.g., Erythromycin, Azithromycin and Clarithromycin
These antibiotics work by inhibiting protein synthesis by binding to the 50s ribosomal subunit. Most common adverse effect is diarrhoea.
Azithromycin is given orally once a day, it has a very long half life so is most commonly used. This cannot be given intravenously
Clarithromycin is 2 times a day
Erythromycin is given 4 times a day and if given intravenously it may cause swelling at the site of injection.
These drugs are often used when a patient has a penicillin allergy
Outline the key characteristics of fluoroquinolone, giving examples and highlighting their mechanism of action, indication and adverse effects.
E.g., ciprofloxacin, levofloxacin, moxifloxacin, ofloxacin
These antibiotics will bind to messenger RNA presently mRNA synthesis and subsequently protein synthesis.
It is indicated for gram-negative bacteria as it has a broad spectrum mechanism of action. Dosing is twice a day. The most common side effect is myalgia (muscle weakness).
Outline the key characteristics of aminoglycosides, giving examples and highlighting their mechanism of action, indication and adverse effects.
e.g., gentamicin, amikacin
These antibiotics work by binding to the 30s ribosomal subunit inhibiting it. These drugs are administered through IV and you can get gentamicin ear drops. Gentamicin has a narrow therapeutic window so must be monitored for nephrotoxicity and ototoxicity.
Outline the key characteristics of Glycoproteins, giving examples and highlighting their mechanism of action, indication and adverse effects.
e.g., Vancomycin
These Antibiotics work by inhibiting cell wall synthesis. They come as both IV and oral formulations. The oral dosing is not absorbed in the GI tract at all. so it is used for C.Diff infections. The IV formulation is however not indicated for C.Diff.
It has a narrow therapeutic window so monitoring is required. It may also cause red man syndrome so the speed of infusion needs to be regulated.
