WEEK 5 Flashcards
(269 cards)
What is MRSA?
MRSA stands for Methicillin-Resistant Staphylococcus Aureus, a type of staph bacteria that is resistant to methicillin and other similar antibiotics.
What is methicillin?
Methicillin is a type of penicillin antibiotic that was developed to overcome resistance from some staph bacteria, but now many strains are resistant to it.
Where do MRSA infections occur?
MRSA can cause infections both in hospitals and healthcare settings (nosocomial) and in the general community.
What is VRSA or GISA?
VRSA stands for Vancomycin-Resistant Staphylococcus Aureus, and GISA stands for Glycopeptide-Intermediate Staphylococcus Aureus; these are staph bacteria that are resistant or partially resistant to vancomycin.
What are glycopeptide antibiotics?
Glycopeptide antibiotics are a class of drugs, like vancomycin, that work by interfering with bacterial cell wall synthesis and are often used for serious Gram-positive infections.
What is VRE?
VRE stands for Vancomycin-Resistant Enterococci, which are types of enterococci bacteria that have become resistant to the antibiotic vancomycin.
What are enterococci?
Enterococci are bacteria that normally live in the intestines and female genital tract but can cause infections if they spread to other parts of the body, especially in hospital settings.
In which patients do VRE cause particular problems?
VRE can cause serious problems in patients whose immune systems are weakened (immunosuppressed), such as those in intensive care units (ICU).
What are Extended Spectrum β-Lactamases (ESBLs) associated with?
ESBLs are associated with resistance in bacteria like P. stuartii (causing UTIs), Klebsiella pneumoniae (causing bacterial pneumonia), P. aeruginosa (in cystic fibrosis), and E. coli.
What is P. stuartii?
P. stuartii (Providencia stuartii) is a bacterium that can cause infections, particularly urinary tract infections (UTIs), and can carry resistance genes like ESBLs on plasmids.
How are ESBLs mediated (spread)?
ESBL resistance can be spread through plasmids (small, transferable pieces of DNA) or can be part of the bacteria’s main genetic material (chromosomally mediated).
What antibiotics do ESBLs inactivate?
ESBLs can inactivate (hydrolyse) even third-generation cephalosporins, but they generally do not inactivate carbapenems.
What other resistances can plasmids carrying ESBL genes confer?
Plasmids carrying ESBL genes also often confer resistance to aminoglycoside antibiotics (like gentamicin) by changing the ribosome, and to quinolones (like nalidixic acid) by altering DNA gyrase.
What is gentamicin?
Gentamicin is an aminoglycoside antibiotic used to treat many types of bacterial infections, especially those caused by Gram-negative bacteria.
What is nalidixic acid?
Nalidixic acid is an older quinolone antibiotic primarily used to treat urinary tract infections.
What is DNA gyrase?
DNA gyrase is an enzyme in bacteria that helps manage the coiling and uncoiling of DNA during replication and transcription; it’s a target for quinolone antibiotics.
What is peptidoglycan?
Peptidoglycan is a polymer made of sugar and peptide (protein-like) units that forms the main structural component of prokaryotic (bacterial) cell walls.
How are Gram positive bacteria characterized visually and structurally?
Gram positive bacteria stain purple with crystal violet-iodine dye and are surrounded by a cytoplasmic membrane and a thick cell wall containing peptidoglycan linked to teichoic acids.
What are teichoic acids?
Teichoic acids are polymers containing phosphate and sugar alcohol units (polyhydroxylated phosphate polymers) found in the cell walls of Gram positive bacteria, helping to maintain cell wall structure and integrity.
How is the cell wall of Gram negative bacteria structured?
Gram negative bacteria have a thinner cell wall (made of peptidoglycan and associated proteins) which is surrounded by an additional outer membrane composed of lipid, lipopolysaccharide, and protein.
What is lipopolysaccharide (LPS)?
Lipopolysaccharide (LPS), also known as endotoxin, is a large molecule found in the outer membrane of Gram-negative bacteria that can cause strong immune responses in humans.
What is the function of the complex cell wall in bacteria?
The complex cell wall helps protect bacteria against the influx of water that could occur due to a higher salt concentration inside the cell compared to outside.
How do β-Lactams interfere with peptidoglycan formation?
β-Lactams interfere with peptidoglycan formation by interacting with Penicillin Binding Proteins (PBPs).
How are PBPs classified?
PBPs are classified by their size, with PBP1 being the biggest, PBP2 the next, and so on.