Antibiotics Flashcards
Why are amimoglycosides inactive against anaerobes and streptococci?
These bacteria do not contain an oxygen dependent transport system
Name the aminoglycosides
Gentamcin, amikacin, neomycin and tobramycin
What are the two major side effects with aminoglycosides?
Nephrotoxicity and ototoxicity
What drugs increase the chance of ototoxicity when prescribed with aminoglycosides
Loop diuretics and vancomycin
What drug(s) increases the chance of nephrotoxicity with aminoglycosides?
Ciclosporin, cephalosporins or vancomycin
Why must you use ibw in dose obese patients with gentamycin?
As this drug is distributed in body water and doesn’t deposit in fat
Name the carbapenems
Meropenem
Ertapenem
Impenem with cilastatin
What activity do carbapenems have?
Broad against Gram +ve, -ve and anaerobes
Which carbapenem has no activity against pseudomonas?
Ertapenem
Why is cilastatin given with imipenem?
Because enzyme activity in the kidneys deactivates the imipenem. Cilastatin inhib these enzymes
Carbapenems have a risk a seizures but one less so. Because if this it can be used for cns infections. Which one is this?
Meropenem
What are the important side effects regarding carbapenems? (3)
Abx associated colitis
Hypersensitivity reaction
Numerological toxicity, like seizures
How does carbapenems interact with warfarin?
Kills natural gut flora that produce vitamin K therefore enhancing warfains affect
Are carbapenems reserved Abx for severe infections?
Yes
How does carbapenems interact with valperate?
Reduces plasma conc and efficacy
How many generations of cephalosporins are there?
5
Name the glycopeptides
Dalbavancin
Teicoplanin
Telavancin
Vancomycin
What are the major side effects of vancomycin?
Nephrotoxicity
Ototoxicity
What happens (if anything) when vancomycin is given as a rapid infusion?
A anaphylactoid reaction can occur. Therefore must be given for at least an hour
Name the macrolides?
Clarithromycin
Azithromycin
Erythromycin
What interaction is there with macrolides and SSRIs?
Both can prolong QT interval
What are the important side effect of carbapenems? (3)
Antibiotic induced colitis
Hypersensitivity
Risk of neurological toxicity
What carbapenem can be given for a CNS infection and why?
Meropenem because they have a lesser seizure producing potential
What major interactions do carabpenems have?
Warfarin - due to the effect of natural gut flora lowering levels of vitamin k
Valporate - as they reduce its plasma concentration and efficacy
What are cephalosporins indicated for?
Septicaemia Pneumonia Meningitis Biliary tract infections Peritonitis UTIs
Cephalosporins penitrate the cns poorly. So why are they indicated in meningitis?
Because in meningitis the meninges are inflamed so they’re able to penitrate
Give a brief description of 1st generation cephalosporins
This have a similar spectrum of activity as penicillin and are useful in respiratory infections, otis media, UTIs and skin/soft tissue infections
In regards to cephalosporins. How does the 2nd generation differ from the 1st?
Has the same spectrum but is poorly absorbed so need to be taken with food
In regards to cephalosporins how does the 3rd generation differ to previous generations?
Great spectrum of activity against gram -ve bacteria
What generation of cephalosporins has the best spectrum of activity?
The fifth generation
What is the target site for macrolides?
50s subunit in the ribosome
What risk is there giving macrolides IV
Thrombophlebitis
What affect can macrolides have on the liver?
Cholestatic jaundice
What side effects can macrolides cause and which one causes them more frequently? (5)
- GI disturbances,
- throbophlebitis (when given IV),
- C.Diff, cholestatic jaundice,
- QT prolongation,
- ototoxicity (at high doses)
Are erythromycin and clarithromycin CYP450 inducers or inhibitors?
Inhibitors
Why are macrolides so good for LRTI?
As they cover atypical penicillin resistant organisms
Name the quinolones
Levofloxacin Ciprofloxacin Moxifloxacin Delafloxacin Ofloxacin
Which quinolone has the greater activity?
Levofloxacin
Which organism has a large prevalence of resistance to quinolones?
Streptococci
What are the MRHA warning regarding quinolines?
- They may indice convulsions in patients with or without a history
- Tendon damage can occur
- High risk of aortic aneurysms
When should caution be taken when using quinolones? (6)
- Cardiac conditions as can prolong QT intervals
- Pts who have a pre disposition to seizures
- Diabetes as can affect blood sugars
- G6PD deficiency
- Children as can cause arthopathy in weight baring joints
- UV exposure
Are quinolones bactericidal or bacteristatic? And what’s their mechanism of action?
Bactericidal by inhibiting DNA synthesis
With quinolone has activity against pseudomonas?
Ciprofloxacin
What are the major side effects of quinolones? (3)
- Low seizure threshold
- Inflame and rupture tendons
- Prolong QT interval
What interactions must you be weary of in regards to quinolones?
Calcium and zinc as they reduce absorption
NSAIDs due to effects of seizure threshold
Prednisolone as they increase tendon rupture risk
Any drug that prolongs the QT interval
Also Ciprofloxacin inhibits some CYP450 enzymes so increases the concentration of theophylline
Name the tetracyclines
Demeclocycline Doxycyline Lymecycline Minocycline Oxytetracycline Tetracycline Tigecycline
What are the main indications for tetracyclines?
Chlamydia
Acne
LRTI
Which tetracycline has the biggest spectrum of activity?
Minocycline
What serious side effect is minocycline associated with?
It can cause lupus erythematosus like syndrome and irreversible pigmentation
Why must you not give tetracyclines to pregnant and breast feeding women?
As they can affect the development of the babies bones
What is the target site for tetracyclines?
The 30s ribosome subunit
What are the 5 major side effects of tetracyclines?
Oesphagael irritation
Photosensitivity
Discolouration and/or hypoplasia of the teeth enamel in children
Hepatotoxicity
Intercraneal HTN (headaches and blurred vision)
What are the interactions to be mindful of with tetracyclines?
Ca, antacids and ieon (chelating effect)
Enhance the affect of warfarin due to its effect on gut flora
Why must you be mindful of renal function when giving tetracyclines?
They can increase urea and also when impaired tetracycline clearance is reduced
What must you be mindful about when giving someone demeclocycline and syndrome of inappropriate ADH?
Demeclocycline can increase the patients sodium
What is metronidazole used for?
Treating anaerobes and protozoa
What is the mechanism of action of metronidazole?
When in an anaerobic bacteria they are reduced into nitroso free radicals interfering with FNA synthesis
When is metronidazole not recommended in women?
During their menstruation
What are the significant side effects of metronidazole?
GI upset
With prolonged use can cause peripheral & optic neuropathy, seizures, encephalopathy and leucopenia
What antibiotics can you not have alcohol with?
Metronidazole as it inhibits acetaldehyde dehydrogenase
What are the most common Bacteria for a skin infection
Staph.Aureus
Streptococci.Pyogenes
Pusedomonus.A
What are the common organisms associated with meningitis?
Streptococci pneumoniae
Meningcocci
H.Influenzea
Listeria
What organisms are commonly associated with eye infections?
Staph.Aureus
Clamidyia
Gonorrhea
What organism is associated with ear infections ?
Streptococci pneumoniae
What organisms are associated with URTI?
Strep.pyogenes
Haemophilia influenzae
What is the organism associated with infections of the stomach?
H.pylori
Name the anti psudomonal penicillins
Tazocin
Ticarcillin with clavulanic acid
Name the broad spectrum penicillins
Amoxicillin
Ampicillin
Co-amoxiclav
Co-fluampicil
Name the beta lactamase sensitive penicillin
Benzylpenicillin
Phenoxylmethylpenicillin
Name the penicillinase resistant penicillin
Flucloxacillin
What is the interaction with penicillins and MTX?
Reduces the renal clearance
What hepatic affects can Amoxcilin or co-amoxiclav cause?
Cholestatic or hepatitis
