Antibiotics and antifungals Flashcards
What is the definition of and antibiotic
chemical substance produced by a microorganism which destroys OR inhibits growth of bacteria and other microbes
Can be naturally ( penicillin G )or synthetically produced ( amoxicillin semi synthetic )
What is a bactericidal antibiotic
One that KILLS the microorganism
What is a bactericidal antibiotic
One that does NOT KILL the bacteria but INHIBITS its growth allowing the body time to mount an immune response and fight the infection
What is the difference between “-cidal” vs “-static: medications
-Cidals KILL - statics inhibit growth
eg fungicidal kill the fungi , fingistakics - inhibit growth
Why use antibiotics in oral health
To treat acute infections so spread does not occur through out the body or tissue
Preventative ( prophylaxis ) - to stop a “ at risk patient getting an infection eg immunocompromised people ( radiation, cancer meds etc )or those at risk of developing endocarditis , or have prosthesis
Name 4 mechanisms by how antibiotics work ( and an 2 examples of each )
They target essential cellular functions
1. Inhibit cell wall synthesis ( block peptidoglycan synthesis of bacteria - so cell fragile and bursts (penicillins/cephalosporins ) bacteriocidal
2.Inhibit protein synthesis via 50S subunit or 30S (tetracyclines/erythromycin)-bacteriostatic
so- mRNA not translate into proteins so cell processes disrupted and not grow further - die
- Inhibit nucleic acid synthesis(DNA/RNA synthesis )-Rifamycin ( RNA polymerase ) ,Quinalones DNA gyrase ( both bactericidal)
4.Disrupts cell membrane function -polymyxin (bactericidal)- by interacting with Lipopolysaccahrides (LPS) so increased leakage out of cells
How 4 ways antifungals work-with an example
- Inhibit cell wall synthesis by inhibiting gluten synthesis eg echinocandins
- Inhibit nucleic acid synthesis (DNA/RNA synthesis )
eg 5-fluorocystosine ( fungicidal ) - Inhibit membrane integrity - eg Polyenes - so H+ and K+ leak out ( fungicidal ) - lots SE if give iv
- Stop sterol biosynthesis - eg -azoles ( fluconazole ) ( fungistatic )
How do we treat oral candidiasis-3 options
1.Amphotercin B lozenges (Polyene - stops membrane integrity )-fungicidal
2.Miconazole oral gel - (stops sterol synthesis ) fungistatic
3.Fluconazole tablets - lots side effects ( stops sterol synthesis )
Name 2 potential therapy issues of oral candidosis treatment
Fluconazole resistance
Reoccurrence
Patient compliance
Other side effects (lots if give polyenes iv)
What is an ideal antibiotic
One that targets a specific pathogen(s) with NO resistance developed -
What is antibiotic resistance
Worldd wide problem
As most antibiotics are BROAD SPECTRUM , they cause collateral damage to the microbiome killing off good bugs as well as some strains develop resistance and pass that down as survive
Name a way to overcome antibiotic resistance in pathogens
Use double antibiotic treatment
Name some unwanted side effects of antibiotics
Beta lactam - diarrhoea /allergy
Polymyxins/Amphotercin B /Aminoglycosides - kidney damage
Tetracycline- teeth stained yellow
Rifampicin - red man syndrome
metronidazole - Black hairy tongue
What is red man syndrome
Seen with rifampacin treatment - bright red/orange sweat/saliva/urone and skin red - due to metabolic products of drug accumulating and get removed by sweat glands ( can wash away BUT )
Can cause liver damage - can be permanent
What’s a bacteriocin
Non traditional antibiotic - they are a proteinaceous antimicrobial produced by a bacteria that kills or inhibits growth of a species closely related to the producer organism- 4 different classes for Gram +ve and 4 types for Gram -ve
