Bacterial resistance Flashcards
(18 cards)
What is the significance of Vancomycin-resistant Enterococcus?
Causes difficult-to-treat hospital-acquired infections such as urinary tract infections, bacteremia, endocarditis, and meningitis
First reported in 1987; majority of vancomycin use in hospitals is inappropriate
What are the main resistant phenotypes of Vancomycin-resistant Enterococcus?
VanA, VanB, VanC
These phenotypes involve changes in the peptidoglycan terminus
What is the mechanism of action of vancomycin?
Non-covalent binding to D-Ala-D-Ala terminus of peptidoglycan, blocking transglycosylation and transpeptidation
This inhibits the growth and strength of the bacterial cell wall
What are the key genes encoded by the VanA transposon responsible for vancomycin resistance?
vanH, vanA, vanX
These genes alter the peptidoglycan terminus from D-Ala-D-Ala to D-Ala-D-Lact
True or False: Vancomycin resistance in Enterococcus results from a loss of a single hydrogen bond.
True
This reduces the affinity of vancomycin to the enterococcal cell wall by 1000 fold
What is the importance of Streptococcus pneumoniae in the U.S.?
Emergence of nonsusceptible strains and significant cause of invasive disease
Resistance trends have been monitored from 1980 to 1997
What percentage of patients with a viral upper respiratory infection should receive an antibiotic?
0%
Antibiotics are not indicated for viral infections like the common cold
What is the role of the mecA gene in Methicillin-resistant Staphylococcus aureus (MRSA)?
Encodes for an abnormal low-affinity penicillin binding protein (PBP-2a)
This allows MRSA to grow in the presence of beta-lactam antibiotics
Which infections are commonly caused by Methicillin-resistant Staphylococcus aureus (MRSA)?
Skin infections, bacteremia, endocarditis, osteomyelitis
MRSA is a major cause of community-acquired and healthcare-associated infections
What factors contribute to the resistance of Enterococcus?
Increased use of oral vancomycin, broad-spectrum antibiotics, agricultural use of avoparcin
The use of avoparcin in agriculture was banned by the EU in 1997
What is the main cause of fluoroquinolone resistance in Streptococcus pneumoniae?
Point mutations (SNPs) in genes encoding for topoisomerases
These mutations reduce the antibiotic’s affinity to the target enzymes
What is the trend of Methicillin-resistant Staphylococcus aureus in U.S. hospitals?
Rapid increase since the 1960s, with significant prevalence among inpatients
In 2006, 46 of every 1,000 inpatients were infected or colonized with MRSA
Fill in the blank: The acquisition of the _______ transposon in Enterococcus is responsible for vancomycin resistance.
vanA
What are the common antibiotic-resistant Gram-positive bacteria mentioned?
Vancomycin-resistant Enterococcus, Streptococcus pneumoniae, Methicillin-resistant Staphylococcus aureus
These bacteria pose significant public health challenges
What are the principles of judicious antimicrobial use regarding the common cold?
Antimicrobial agents should not be given for the common cold
Purulent rhinitis is not an indication for antimicrobial treatment
What is the impact of inappropriate antibiotic use on antibiotic resistance?
It fuels the problem of antibiotic resistance
The rise of drug-resistant bacteria is linked to misuse of antibiotics
True or False: Community-associated MRSA strains are the same as those causing healthcare-associated infections.
False
Community-associated strains tend to be more resistant to oral antibiotics
What is the trend of antibiotic resistance in invasive pneumococcal disease from 2005 to 2018?
Changes in the incidence of nonsusceptible strains observed
Particularly noted among children under 5 and adults over 65
