Antimicrobials Flashcards
What are microorganisms + the types?
Most are harmless cells and many make crucial contributions to mankind.
Pathogenic ones must be identified so correct treatment can be prescribed.
Types: Bacteria Fungi Yeasts Protozoa Viruses
What is the typical bacterial cell structure?
Cell wall Cell membrane Cytoplasm Ribosomes Plasmids DNA Pili (to adhere to other cells) Flagellum (for motion)
What are the identifiable features of bacteria?
Size, shape, lab staining, growth habits etc.
What are the identifiable features of:
Bacilli
Cocci
Bacilli- rod shaped (escherichia coli)
Cocci - berry shaped (staphylococcus aureus)
How can fungi be identified?
Biochemical characteristics
They grow in long, stringy filaments.
Some produce structures visible to naked eye -mushrooms.
What is Candida Albicans?
Yeast that causes opportunistic infections in immunocompromised patients or following antibiotics.
Thrush.
What are the characteristics of viruses?
Particles rather than living cells.
Very small and only contain their genetic info.
Must enter a host cell to reproduce.
Affect all living cells (humans, animals, plants)
What is antibiotic resistance?
Adaptation of pathogenic bacteria to the presence of antibiotics in environment.
The more exposure they receive to antibiotics the faster they become resistant.
As antibiotic resistance grows the ability to treat serious infections is reduced.
What is bacterial resistance to antibiotics?
Original antibiotics come from nature.
Microbes have innate protection and can also develop immunity to the antibiotics produced by other microbes.
When a microbe possesses or develops and immunity to a prescribed drug we say it is resistant.
What is innate resistance?
Resistance already possessed by the organism.
Dependent on mechanism of action of drug and the biochemistry of the organism.
Viruses have innate resistance to all antibiotics as they do not use the same pathways that antibiotics target.
What is acquired resistance?
Bacteria can develop resistance to an antibiotic :
By gaining a protective gene from another cell (usually by plasmid transfer)
By spontaneous mutation of one or more of their genes into resistant genes.
What are the major sites of antibiotic action and what antibiotics target each one?
Cell wall - penicillin
Protein synthesis - clindamycin, tetracycline, erythromycin, chloramphenicol
DNA replication - metronidazole
Folic acid metabolism - trimethoprim, sulphonamide 1
How do penicillins work + where are they absorbed/excreted?
Prevents last stages of cell wall synthesis, weakening cell wall and causing bacterium to burst due to osmotic pressure.
Absorbed from GI tract into plasma.
Excreted by renal tubules into urine, bile.
What are the side effects of penicillins?
Nausea Vomiting Stomach pain Headache Diarrhoea Yeast infection
What are the main penicillins?
Benzyl penicillin (PEN G) - least toxic, potent, narrow spectrum.
Phenoxymethylpenicillin (PEN V)
Ampicillin
Amoxicillin
