Antimicrobial Chemotherapy from POD Flashcards
What class of drug does daptomycinbelong to?
Cyclic Lipopeptide
What is the standard length of an antimicrobial course?
7 days
What are the three ways antibiotics work?
Inhibition of cell wall synthesisInhibition of Protein synthesisInhibition of nucleic acid synthesis
How is aciclovir administered?
Orally or intravenously
Where are beta-lactamases common?
In Gram negative Bacilli
What is the activity of daptomycin?
Good activity against gram positive bacteria in general and MRSA in particular(inhibition of protein synthesis)
What antibiotic is associated with optic nerve damage? (optic neuropathy)
Ethambutol
What are ESBL’s?
Extended spectrum beta lactamses - they are resistant to all beta lactamases
What are CPE’s?
Carbapenemase producing Enterobacteriaceae, they are extremely resistant gram negative organisms - resistant to the carpebenems.
What is Tenofovir used for?
Hepatitis B
What can happen to stop Beta lactams binding to PBP’s?
Mutations in PBP genes, resulting in a modified target site, to which beta lactams will no longer bind
What are the susceptible groups who need extra care when administering antimicrobials?
Extremes of age, pregnant women, patients with renal or liver insufficiency.
What is the spectrum of glycopeptides?
They act against ONLY gram positive organisms - both aerobic and anaerobic
What is the difference between Nalidixic acid and Nitrofurantoin?
Also effective against some gram positive bacteria.
What is the effect of trimethoprim and sulphamethoxazole?
Inhibit different steps in purine synthesis
What drug can be used against the herpes simplex virus and the varicella zoster virus?
Aciclovir
What are the side effects of vanomycin?
Otoxicity, nephrotoxicity and skin rashes
What is the disadvantage of clindamycin?
Common cause of pseudomembranous collitis
What is defined as clinical resistance?
When the organism is unlikely to respond to attainable levels of that drug in the tissues
What is Voriconazole used to treat?
Aspergillosis
What is used to treat chronic hepatitis B and C infections?
Interferon - a
What are the signs of delayed hypersensitivity?
Drug rashes, drug fever, serum sickness and erythema nodosum
What is Nitrofurantoin active against?
Most gram negative organisms with the exception of pseudomonas and proteus
What is cystitis?
Lower urinary tract infections
What is special about the treatment of pseudomonas with ciproflaxin?
It is the only oral therapy available
How do aminoglycosides lyse most gram negative cells?
By inhibiting protein synthesis Staphylococci are also sensitive to aminoglycosides, streptococci are not
Describe the combination therapy used to treat patients with HIV
Combination therapy with at least three drugs.Drugs are active on at least two different stages of the HIV replication.Examples of the actions of these drugs :1. Analogue nucleoside which inhibits reverse transcriptase2. Non-nucleoside reverse transcriptase inhibitor3. Protease inhibitor which inhibits viral protease enzyme.
When is genotypic analysis of a virus useful?
May help choosing rational treatment in selected patients
What is the advantage of Teicoplanin?
Less toxic, single daily dosing advantage
Do all strains of C.diff produce toxins?
NO
What is metronidazole effective against?
It is a miscellaneous Antibiotic - effective against both gram negative and gram positive bacteriaResistance against anaerobes is virtually unknownNo useful activity against aerobes
What is ribavarin used for?
Treatment of severe respiratory syncytial virus infections.Used in combination treatment for chronic hepatitis C with Interferon - a
How is treatment of C.Diff achieved?
Metronidazole or oral vanomycin (not absorbed in the GI tract so it is the only circumstance where the oral form is used.
What form of penicillin has a better absorption when taken orally?
Phenoxymethylpenicillin,as well as amoxicillin and ampocillin (these confer better gran negative activity)
How is ribavarin administered?
Inhaled as a fine spray
Give an example of a oxazolidinone
Linezolid - protein synthesis inhibitor
What is the effect of zidovudine?
Nucleoside analogue Interferes with the action of reverse transcriptase.Slows down the replication of the virus but does not kill it. Prolongs survival of AIDS patients
What is a cause of diarrhoea that is associated with antibiotic therapy?
Diarrhoea associated with toxin production by clostridium difficile. It overgrows normal flora during therapy
What can cause an overgrowth in candida albicans?
Broad spectrum penicillins or cephalosporins causing oral and or vaginal candidiasis, also known as thrush
Give examples of cidal drugs
B lactams, aminoglycosides, glycopeptides and quinolones
Which drugs are usually associated with nephrotoxicity and ototoxicity?
Aminoglycoside (gentamicin) or with vanomycin
What is the main cause of CDI in recent years?
Use of broad spectrum antibiotics
Is C.diff killed by alcohol hand rub?
NO
When do patients require several weeks of antimicrobial therapy?
Patients with osteomyelitis, endocarditis
What can linezolid be used to treat?
MRSA
What is the only polyene available for intravenous polyene use?
Amphoterecin BTreats serious systemic fungal infectionExtremely toxicRenal, Hepatic and cardiac toxicity
Describe the activity of cephalosporins against gram negative and gram positive bacteria as the generation number increases
Gram negative activity increases - even effective against Pseudomonas Gram positive activity decreases
What is the most common and cheapest aminoglycoside?
Gentamicin
What is the effect of the liver on the antimicrobials?
Metabolised by the liver and excreted in bile
What is the function of Allylamines?
Suppress ergosterol synthesis, but act on a different stage of the synthetic pathway from Azoles.
What are penicillin binding proteins?
Enzymes responsible for peptidoglycan synthesis
What is the other polyene in clinical use?
Nystatin - available for topical use only (fungal skin infections in pessaries for vaginal candida infections) and in oral suspension (for oral and oesophageal candidiasis)
What determines the choice between Vanomycin and teicoplanin?
The two glycopeptides have the same spectrum of activity, the choice is however dependant on cost
What drugs are associated with hepatotoxicity?
Tetracyline, isoniazid and rifampicin (anti tuberculosis drugs), flucloxacilin
What are examples of Echinocandins?
Caspofungin, Mycafungin and anidulafungin
Describe the problems associated with Fluconazole and resistance
Resistance among some candida species is emergingMajority of Candida albicans (commonest species of yeast associated clinical infection) with strains remain sensitive but resistance can emerge during treatment,
Why has cephalosporin use decreased over recent years?
They appear to encourage clostridium difficile infections
What drugs are both licensed for the treatment of influenza and what are there limitations?
Zanamavir and Oseltamavir Used to treat A or B within 48 hours of symptoms and also for post-exposure prophylaxis.
Describe the resistance of bacteria with modified PBP’s against beta lactams
Resistant to all beta lactam agents
Describe the action of fluconazole
Used for oral and parenteral treatment of yeast infections (no activity against filamentous fungi-aspergillus)
What is the first choice treatment against staphylococcal infections (which are gram positive btw)? And Why?
Flucloxacillin - resistant to the actions of staphylococcal beta lactamase.
What can linezolid cause?
Bone marrow suppression
What are the different forms of fungi?
Yeasts and filamentous fungi (moulds)