Outline a classification of antimicrobials (4)
-bactericida (kills) or bacteriostatic (inhibits)
-spectrum> broad vs narrow
-target site (mechanism of action)
-chemical structure of antibiotic
every class of Antibacterials have their own mechanism of actions,
Describe the mechanism of action of the main groups of antimicrobials and guv eexamples.
Describe the principles of antimicrobial resistance and its impact on antimicrobial prescribing.
Describe the concept of antimicrobial stewardship
Outline measures to take to ensure the appropriate use of antimicrobials
what is an antimicrobial?
an agent that is active against small microbes, either protozoa, antifungal, anti viral,
what is an antibiotic?
an agent derived from another living creature.
ex: penicillin is developed from the mould penicillium.
what r the ideal features of antimicrobial agents?
-selective toxicity (we want it to be more toxic to the microbe than the host)
-few side effects
-reach infection site (ex: meningitis, we want it to get to csf.)
-longer half life
-doesn't interfere with other drugs -
EVERY drug has some kind of degree of toxicity on the HOST cell too lil 2asaf ;(
so we try to find a drug that would to be more toxic to the microbe than the host
where do we want to target the drug when treating meningitis?
types of resistance
-intrinsic: if the bacterium has no target for the drug, or the drug can't get into the bacterium.
-acquired the microbe changes genetically either by mutation or acquires a new genetic material (look at ur notes alaa)
what is trimethoprim? describe its mechanism of action
treatment of UTI, it interferes w/ folic acid synthesis, which is responsible in NUCLEIC ACID synthesis.
**A potent inhibitor of bacterial dihydrofolate reductase. Leading to a decreased availability of the tetrahydrofolate cofactors required for purine, pyrimidine, and amino acid synthesis
describe the cell wall synthesis in bacteria
NAM and NAG from the peptidoglycan layer peptidoglycans r cross linked together via PBP (transpeptidase)
Mechanism of action of Flouroquiolones
it interferes with nucleic acid synthesis.
works by inhibiting 2 of the enzymes involved in dna replication,
-DNA Gyrase -Topoimerase that r involved with supercoiling
what r the 3 mechanisms of bacterial resistance?
-Enzymes bacteria can make enzymes that can inhibit the drug! ex: B lactamases will inactive the B lactam ring in the drug (ur notes alaa) - Altered target Ex: MR SA a bacteria which is resistance to Metacillin. -Altered uptake 1) LOW permeability>> drug can't get inside the organ 2) EFFLUX pump>>drug can get in, BUTT an efflux pump developed to push the drug out!
describe the genetic basis of antibiotic resistance
1) chromosomal gene mutation During bacterial division, by chance, there has been a mutation, and the plasmid carries a 'RESISTANT GENE" in the presence of an antibiotic, all the susepitble ones r killed, but the one that had the mutation survived IT BECOME THE DOMINANT STRAIN! and that organism is now resistance. it has been selected by the us of antibiotics. 2) Horizontal gene transfer -conjugation (sex pili) -transduction (injected in bacteria via bacteriophage) -transformation
what is a spore?
how can u measure antibiotic activity?
via disk sensitivity testing. -grow the organism on an agar plate -put a little paper filtered disk that has antibiotic. -antiobiotic diffuses into the agar **if antibiotic is effective, it won't grow in that area (clear space)
which group does Flucloxacillin fall into? what is it active against?
Penicillin **staph and Strep cocci
which group does ceftriaxone fall into? give example of when we administer it
make a list of the 3 bacteria and 3 viruses that r the main causes of community-acquired pneumonia
what type of gram stain is Streptococcus?
what PO and BD stands for?
what is Amoxicillin most active against?
describe characteristics of cephalosporins?
in the ER, a pateint comes in with emergency case of meningitis, what antibiotic do u administer and why?
cetriaxone it penetrates well in the CSF Used in EMERGENCY situation in meningitis
describe characteristics of carbapenems?
what is Fluconazole used for?
to treat Candida can be used orally and IV used for oral and vaginal thrush can be used also in imuunocompirompised patients
name 2 classes of anti fungal drugs & their mechanism of action
-Azoles>> Inhibit cell membrane synthesis -Polyenes>>inhibit cell membrane function
name 2 classes of anti viral drugs & their mechanism of action
-Aciclovir When phosphorylated, inhibits viral DNA polymerase ~herpes ~varicella zoster -Oseltamivir (tamiflu) Inhibits viral neuraminidase Influenza A&B
Use of some antibiotics is linked to increase susceptibility to clostridium difficile infections. What is the mechanism behind this?
Clostridium difficile exerts its pathological effects by producing toxins. What are these toxins and how do they work?
treatment advice for Clostridium difficile
How is the severity of the infection assessed? What different antibiotics are advised for treatment?
Clostridium difficile is part of a group of clostridium bacteria. Can you name the other bacteria in this group and diseases that they might cause?
A man has an abssess on his skin and has grown Meticillin-Resistant Staphylococcus aureus (MRSA). The abscess did not respond to the initial treatment and the patient is systemically unwell and therefore admitted to hospital. What antibiotic do you prescribe for the MRSA? What class of antibiotic is this? How would u adminuster it and why?
Vancomyocin Glycopeptide IV, bc vancomyocin is not absorbed into the blood, and the abssess is due to a systemic inflammation, so we give it via IV to target it to the blood
Which amtibiotic is active against chlamydia amd shouldnt be given to children under 12?
Tetracycline and doxycycline
What is aciclovir?
Antiviral agent used for herpes and varicella zoster.
When do we give vancomyocin orally?
For c.difficle ONLY since its in the large bowel, and vancomyocin is not absorbed in blood. So its perfect to target in bowel
Classify gentamicin, againt which gram? when is it used?
Gentamicin >> we hate "gents">> negative Good activity in blood/urine -nephrotoxic/ototoxic -Generally reserved for severe Gram neg sepsis
what is PUS?
dead or dying white blood cells and cellular debris (toxin damage on surrounding tissue) and serous fluid and fibrin and bacteria.
in what ways does staph aureus cause akin abssess? what virulence factor contributes to this? what antibiotic do u prescribe for MRSA? how would u administer it and why?
S. aureus infections causes a rapid and extensive influx of white blood cells (e.g., neutrophils). S. aureus lyse neutrophils and red blood cells that have entered the infection area. The lysed neutrophils pour out large amounts of lysosomal enzymes, which damage surrounding tissue. -vancomyosin, GLYCOPEPTIDE we give it IV, bc we want it to be targeted to the BS, if we give it orally it'll end up in the stomach and won't get absorbed.
In January an 85 year old lady presented history of vomiting and diarrhoea. She appeared to be dehydrated and was admitted up to a 6 patient bay on the ward for IV fluids. The following day 3 patients and one member of staff seem to develop similar symptoms and things only get worse when the day after 9 patients appear to have developed gastroenteritis and 5 members of staff call in sick. What is likely infection? What js transmission of route? What precaustion must take
Norovirus>> caus eof gasteroenteritis in adults Fecal oral, or injestion food, contaminate
MRSA = Meticillin-Resistant Staphylococcus aureus How MRSA is spread? Treatment for MRSA
MRSA produces penicillin binding protein 2a, which confers resistance to all β lactam antibiotics. -skin-skin contact -spread through sheets, towels, clothes, dressings w/ someone with MRSA -Treatment of carriage using topical applications of mupirocin nasal cream (a topical antibiotic) and washing with disinfectant agent, such as stellisept or chlorhexidine.
How effective is hand hygiene in MRSA?
MRSA spreads from patient to patient via the hands of health-care providers. Therefore, most experts agree that hand hygiene during patient care is the most important measure to reduce the spread of MRSA in the health-care setting.
how is Norovirus treated?
There is no specific treatment available so treatment consists of supportive measures.
**Hand hygiene remains the cornerstone for effective control in hospitals
Use NAF for STAPH
nafcillin for staphylococcus
adverse effects of flouroquinolones?
flouroquinoLONES hurt attachmentds to ur BONES can cause tendonitis or tendon rupture
--forms toxic free radical metabolites in the bacterial cell that damages DNA