Antibacterial protocols 7.4 Flashcards
Cephalosporins and Cephamycins are antibacterial agents that are isolated from?
the mold Cephalosporium
Cephamycins are closely related to the
cephalosporins, except that they contain?
oxygen in place of sulfur in the dihydrothiazine ring. THIS renders them more stable to β-lactamase hydrolysis
does penicillin or Cephalosporins/Cephamycins have a wider antibacterial spectrum?
Cephalosporins and Cephamycins
Cephalosporins and Cephamycins are RESISTANT to?
resistant to many β-lactamases
Name antibiotics that interfere with constuction of bacterial cell wall
1) Penicillin
2) Cephalosporins and Cephamycins
3) vancomycin
4) Daptomycin
5) Bacitracin
6) antimycobacterial agents: isoniazid, ethambutol, cycloserine, and ethionamide
Vancomycin was originally obtained from?
Streptomyces orientalis
Vancomycin disrupts? G- or G+ ?
Disrupts peptidoglycan synthesis in gram-positive bacteria
Vancomycin interacts with what in order to form interpeptide bridges?
interacts with D-alanine-D-alanine termini of pentapeptide interfering with formation of interpeptide bridges
Vancomycin is inactive against G- or G+ bacteria? why?
inactive against gram-negative bacteria, because its too large for porins
what is resistant to Vancomycin?
- *Intrinsic resistance to vancomycin= Leuconostoc, Lactobacillus, Pediococcus, Erysipelothrix, AND Enterococcus gallinarum, Enterococcus casseliflavus
- *aquired resistance
Bacitracin Isolated from?
Is a mixture of?
G- or G+ are resistant to Bacitracin?
Bacillus licheniformis
*a mixture of polypeptides
G- are resistant
Bacitracin is used in?
creams, ointments, sprays for skin infections caused by gram-positive bacteria (Staphylococcus and group A Streptococcus)
Bacitracin Inhibits cell wall synthesis by interfering with?
bactoprenol carrier of peptidoglycan precursors
Bacitracin Resistance to antibiotic is caused by?
failure of the antibiotic to penetrate into the bacterial cell
Isoniazid, Ethionamide, Ethambutol, and Cycloserine 1) used for treatment of? 2) bactericidal against actively replicating? 3) synthesis of \_\_\_\_ acid is affect 4) mechanism of action?
1) treatment of mycobacterial infections
2) Bactericidal against actively replicating mycobacteria
3) Synthesis of mycolic acid is affected
4) mechanism of action is unknown
Ethambutol interferes with the synthesis of?
arabinogalactan in cell wall
Cycloserine inhibits?
D-alanine-D-alanine synthetase
and alanine racemase, for cell wall synthesis
What all inhibits nucleic acid synthesis?
Quinolones and Rifampin and Rifabutin,
examples of Quinolones?
nalidixic acid, ciprofloxacin, levofloxacin, and moxifloxacin
Quinolones have excellent activity against?
gram-positive and gram-negative bacteria, although resistance can develop rapidly
newer extended-spectrum Quinolones have significant activity against? Ex?
gram-positive bacteria
Ex:moxifloxacin
what is the promary Quinolones target in G- bacteria? G+?
G-= DNA gyrase-A subunit aka topoisomerase type II G+= topoisomerase type IV
What do Quinolones do?
A widely used class of antibiotics that inhibit bacterial DNA topoisomerase type II (gyrase) or topoisomerase type IV, required for DNA replication, recombination, and repair
Rifampin and Rifabutin is a semisynthetic derivative of rifamycin B produced by?
Streptomyces mediterranei
What does Rifampin and Rifabutin do?
binds to DNA-dependent RNA polymerase and inhibits initiation of RNA synthesis
Rifampin and Rifabutin is very active against? Bactericidal for?
aerobic gram-positive cocci, including
staphylococci and streptococci BUT resistance can develope rapidly
**Bactericidal for Mycobacterium tuberculosis
why is Gram-negative bacteria are resistant intrinsically to rifampin?
because of decreased uptake of the hydrophobic
