Hospital-acquired infections Flashcards
(16 cards)
Why does antibiotic resistance occur?
Antibiotics act as a selection pressure to microbes, which then express preferable genes that offer resistance in order to stay alive.
What were the three misconceptions with regards to antibiotic resistance?
That resistance to more than one antibiotic class would not occur
Horizontal gene transfer would not occur
Resistant organisms would be less potent
Why does antibiotic resistance lead to increased mortality, morbidity and length of stay?
Increased time is needed to provide an effective therapy
Additional approaches are needed
Newer, more expensive therapy is sometimes needed
More toxic drugs needed
What are the major Gram +ve AB resistant pathogens?
Staph aureus
Strep pneumoniae
C. difficile
Mycobacterium tuberculosis
What are the major Gram -ve AB resistant pathogens?
E. Coli
Salmonella spp.
Neisseria gonorrhoeae
What are the types of antibiotic?
Beta-lactams
Quinolones
Sulphonamides
Amino-glycosides
Macrolides
How do beta-lactams inhibit microbes? Give an example of one.
interfere with cell wall synthesis
Penicillin
How do quiniolones inhibit microbes? Give an example of one.
Target DNA gyrase, inhibiting DNA replication and transcription
How do sulphonamides inhibit microbes? Give an example of one.
Bacteriostatic drugs - competitive inhibitor of folate synthetase
How do amino-glycosides inhibit microbes? Give an example of one.
Target protein synthesis - 30S subunit and damage cell membrane
Gentomycin
How do macrolides inhibit microbes? Give an example of one.
Target Gram +ve - 50S ribosomal subunit so no aminoacyl transfer
Erythromycin
What are the four mechanisms of AB resistance?
Altered target site - alternative gene
Inactivation of AB - enzyme degradation
Altered metabolism - out-compete inhibitor
Decreased drug accumulation - AB can’t penetrate - ineffective conc
Give the sources of antibiotic resistant genes
Plasmids - circular DNA
Transposons - integrate into chromosomal DNA
Naked DNA - DNA from dead bacteria
Give other reasons of treatment failure
Inappropriate choice for organism
Inappropriate dose, administration poor penetration
WHat are the risk factors for HAI?
Hospitals provide strong selective pressure for AB resistance
Large number of infected people
Crowding
Broken skin
How can resistance be addressed and overcome?
Modification of existing medicines
Tighter control of prescribing strategies
Reduction of broad-spectrum AB
