Antibiotic Resistance Flashcards
What are the current major clinical problems?
MRSA
Carbapenem-resistant enterobacteriaceae (CRE)
How often do infections occur after surgery?
3%
What are some examples of CREs?
Escherichia coli
Klebsiella pneumoniae carbapenems
Salmonella
Is CRE gram-positive or gram-negative?
Gram-negative
What are the chances of dying with a CRE infection?
Approximately 50%
What are the resistance mechanisms of bacteria?
Keeping antibiotics outside of the cell
Destroy or inactive antibiotic
Modify molecular target of antibiotic
What is a difference between penicillin and vancomycin to gram-negative bacteria?
Penicillin can cross the outer membrane by the porin channels whereas vancomycin cannot
What does a mutation in ompF lead to?
impermeable porins leading to resistance
What is an example of a bacteria that has ompF and ompC?
E. coli
What is intrinsic resistance?
innate ability of bacteria to resist antibiotic through its normal structure/function e.g. cell envelope, ribosome structure
What is acquired resistance?
susceptible bacteria acquires resistance gene from another bacteria species/strain via HGT
What is HGT?
Horizontal gene transfer
What is an example of a bacteria with porin channels of low permeability?
Psuedomonas aeruginosa
Ampicillin is used to treat E. coli , what spectrum drug is it?
Broad
How do bacteria increase export of antibiotics?
Efflux pumps
How does bacteria work against beta-lactam antibiotics?
Beta-lactamases which are hydrolytic enzymes that destroy/inactivate the antibiotic
Where is Staphylococcus aureus found?
Nose Skin folds Hairline Perineum Navel
What relatively minor infections are caused by Staphylococcus aureus?
Abscesses
Impetigo
Minor skin infections
What more serious problems are caused by Staphylococcus aureus?
Cellulitis Post-operative infection Pueruperal fever Catheter infections Toxic shock syndrome
What does MRSA stand for?
Meticillin resistant staphylococcus aureus
What percentage of S. aureus bacteraemias are MRSA?
30%
Why are there many HA-MRSA?
Puncturing of the skin
Catheters, IVs, surgery
What is the difference between HA-MRSA and CA-MRSA?
HA-MRSA is more prevalent but CA-MRSA is more virulent
How long did it take for S. aureus to become resistant to Meticillin?
1 year
What allow S. aureus to be MR?
Chromosomal macA encodes altered PBP2’ (penicillin binding protein 2) - allows cell wall biosynthesis to continue
What allows rapid spread of vancomycin resistant S. aureus?
VanR genes are mobile (transposons, plasmids)
What are the new last resorts in treating MRSA?
Tigecycline
Linezoloid
How is MRSA screened for?
Nose swab (or armpit/groin) -> sent to lab
How to decolonise MRSA?
Nasal spray, body wash, shampoo with anti-MRSA
Prontoderm
Chlorhexidine glucognate
Mupirocin
