ceph 2 Flashcards
What is Cepll’lamycijns?
Isolated from a culture of Streptomyces clavuligerus
First 13-lactam to be isolated from a bacterial source. Modifications carried out on the 7-acylamino side chain.
What is Cefoxitin?
Broader spectrum of activity than most first generation cephalosporins
Greater resistance to beta-lactamase enzymes due to the methoxy group at position 7.
What role does the 7-methoxy group play in Cefoxitin?
Acts as a steric shield
It contributes to greater resistance against beta-lactamase enzymes.
What is the significance of the urethane group in Cefoxitin?
Stable to metabolism by esterases
This stability contributes to its pharmacological properties.
What are the characteristics of Cefuroxime?
Much greater stability against some beta-lactamases
Resistant to esterases due to the urethane group; useful against organisms resistant to penicillin.
True or False: Cefuroxime is active against P. aeruginosa.
False
Cefuroxime is not active against P. aeruginosa.
What is the function of the aminothiazole ring in third generation cephalosporins?
Enhances penetration across the outer membrane of Gram -ve bacteria
May also increase affinity for the transpeptidase enzyme.
What is Ceftazidime known for?
Excellent activity vs. P. aeruginosa and other Gram -ve bacteria
It can cross the blood-brain barrier.
What are the properties of fourth generation cephalosporins?
Zwitterionic compounds
Enhanced ability to cross the outer membrane of Gram negative bacteria and good affinity for the transpeptidase enzyme.
What is the antipseudomonal activity of Cefoperazone?
Yes
Cefoperazone has good antipseudomonal activity.
Fill in the blank: Cephalexin is a ______ generation cephalosporin.
First
What is the plasma protein binding percentage for Ceftriaxone?
80-95%
It has good extended spectrum activity.
Which cephalosporin generation is Cefuroxime classified under?
Second
What is the oral bioavailability of Cefixime?
Yes
Cefixime is available in oral form with good extended spectrum activity.
What is the general activity of first generation cephalosporins against Gram +ve cocci?
Broad
They are generally effective against Gram +ve cocci.
What is the resistance level of Cefamandole against beta-lactamases?
Poor to average
It is administered parenterally.
True or False: All second generation cephalosporins are resistant to beta-lactamases.
False
Some second-generation cephalosporins have variable resistance levels.
What is the significance of the term ‘extended spectrum’ in cephalosporins?
Indicates activity against a wider range of bacteria
Extended spectrum cephalosporins are useful against resistant organisms.
