Cephalosporins: Structure and Classification

Questions and Answers

What is the main difference between cephalosporins and penicillins?

Cephalosporins are more resistant to beta lactamase inactivation

Which generation of cephalosporins is active against E. coli, Klebsiella, and Proteus?

2nd Generation

What is the primary use of 1st Generation cephalosporins?

Treat skin and soft-tissue infections, as well as streptococcal pharyngitis

What is the main advantage of 3rd Generation cephalosporins?

Better activity against gram-negative organisms Signup and view all the answers

Which of the following is a characteristic of cephalosporins?

They consist of a six-membered dihydrothiazine ring fused to a beta lactam ring Signup and view all the answers

What is the primary limitation of cephalosporins?

They are prone to hydrolytic degradation Signup and view all the answers

What is the mechanism of action of Aminoglycosides?

They inhibit bacterial protein synthesis by binding to the 30s subunit and blocking tRNA binding to the A site. Signup and view all the answers

Which of the following is NOT a use of Streptomycin?

Urinary tract infections Signup and view all the answers

What is a unique property of Meropenem?

It is resistant to dehydropeptidase enzyme. Signup and view all the answers

Which Aminoglycoside is most active among the Nebramycins?

Tobramycin Signup and view all the answers

What is a characteristic of Macrolides?

They contain a many-membered lactone ring. Signup and view all the answers

What is the mechanism of action of Ertapenem?

It inhibits bacterial cell wall formation. Signup and view all the answers

What happens when Azithromycin is administered with food?

Food has no significant effect on absorption Signup and view all the answers

Which antibiotic is a derivative of dichloroacetic acid?

Chloramphenicol Signup and view all the answers

Which antibiotic is a reversible inhibitor of CYP3A4 enzyme?

Telithromycin Signup and view all the answers

What is the mechanism of action of Clindamycin?

Binds exclusively to the 50S subunit of bacterial cell Signup and view all the answers

Which antibiotic is effective against macrolide-resistant G(+)?

Telithromycin Signup and view all the answers

What is the spectrum of activity of Clindamycin?

Bacteriostatic against S.epidermidis, S.aureus, M.pneumonia, and bactericidal against H.influenzae, N.meningitides, B Signup and view all the answers

What is the primary mechanism of action of Cephalosporins against bacteria?

Inhibition of cell wall formation Signup and view all the answers

What is the main adverse effect of Cephalosporins due to inhibition of Vitamin K?

Hypoprothrombinemia Signup and view all the answers

Which of the following bacteria is NOT typically treated with Aztreonam?

Staphylococcus aureus Signup and view all the answers

What is the main characteristic of Carbapenems?

Broad spectrum of activity Signup and view all the answers

What is the primary mechanism of action of Olivanic acids?

Inhibition of beta-lactamases Signup and view all the answers

What is the main characteristic of Imipenem?

High beta-lactamase resistance Signup and view all the answers

What is the mechanism of action of quinolones?

Inhibition of Topoisomerase IV and DNA gyrase enzymes Signup and view all the answers

Which of the following quinolones is NOT mentioned in the text?

Cinafloxacin Signup and view all the answers

What is the adverse effect of quinolones that is associated with Hepatotoxicity?

Trovafloxacin Signup and view all the answers

What type of organisms are Polypeptides effective against?

Bacteria Signup and view all the answers

What is the source of Polypeptides?

Bacillus and Streptomyces spp. Signup and view all the answers

What is the therapeutic use of quinolones mentioned in the text?

All of the above Signup and view all the answers

What is the unique property of 4th generation cephalosporins?

Increased stability to hydrolysis by inducible chromosomal β-lactamases Signup and view all the answers

What is the primary adverse effect of cephalosporins due to inhibition of Vitamin K?

Hypoprothrombinemia, leading to an increased tendency to bleed Signup and view all the answers

What is the mechanism of action of Aztreonam?

Inhibition of cell wall formation by binding to PBP3 in Gram-negative bacteria Signup and view all the answers

What is the characteristic of Carbapenems?

Fused β-lactam rings with a broad antimicrobial spectrum Signup and view all the answers

What is the source of Olivanic acids?

Streptomyces olivaceus Signup and view all the answers

What is the characteristic of Thienamycins?

Broad-spectrum antibiotic activity with high β-lactamase resistance Signup and view all the answers

What is the primary use of Aztreonam?

Treatment of Gram-negative bacterial infections, including UTI, LRTI, intra-abdominal infection, gynecological infection, and septicemia Signup and view all the answers

What is the primary characteristic of Monobactams?

Binding to PBP3 in Gram-negative bacteria Signup and view all the answers

Which type of organisms is Lledo effective against?

G(+) and nonspore forming anaerobes Signup and view all the answers

What is the mechanism of action of Quinolones?

Inhibition of Topoisomerase IV and DNA gyrase enzymes Signup and view all the answers

What is a common adverse effect of Quinolones?

GI disturbances Signup and view all the answers

Which of the following Quinolones is NOT mentioned in the text?

Clinafloxacin Signup and view all the answers

What is a therapeutic use of Quinolones mentioned in the text?

UTI Signup and view all the answers

What is the source of Polypeptides?

Bacillus and Streptomyces spp. Signup and view all the answers

What is a characteristic of Polypeptides?

Most powerful antibiotics Signup and view all the answers

What is an adverse effect of Quinolones associated with Tendon Rupture?

Tendon Rupture Signup and view all the answers

What is the primary site of action of Bacitracin?

Cell wall Signup and view all the answers

Which type of leprosy is associated with a malignant course?

Lepromatous leprosy Signup and view all the answers

What is the primary mechanism of action of Amphotericin B?

Interfering with cell membrane function Signup and view all the answers

What is the characteristic shape of Mycoplasma pneumoniae?

Pleomorphic Signup and view all the answers

What is the primary treatment for leprosy?

Dapsone Signup and view all the answers

What is the unique feature of Mycoplasma pneumoniae?

It lacks a peptidoglycan cell wall Signup and view all the answers

What is the primary source of Bacitracin?

Bacillus Signup and view all the answers

What is the term for the treatment of tuberculosis?

TB-DOTS Signup and view all the answers

Which antibiotic binds exclusively to the 50S subunit of bacterial cell?

Clindamycin Signup and view all the answers

What is the main advantage of Clindamycin over Lincomycin?

Improved absorption and distribution Signup and view all the answers

Which of the following antibiotics is a CYP3A4 inhibitor?

Telithromycin Signup and view all the answers

Which antibiotic is produced from Streptomyces venezuelae?

Chloramphenicol Signup and view all the answers

What is the primary use of Clindamycin?

Staph infections, cellulitis, and osteomyelitis Signup and view all the answers

Which antibiotic is not administered with food?

Clindamycin Signup and view all the answers

What is the spectrum of activity of Clindamycin?

Anaerobes, S.epidermidis, S.aureus, and others Signup and view all the answers

What is a unique chemical feature of Chloramphenicol?

Contains a nitrobenzene moiety Signup and view all the answers

What is the mechanism of action of Vancomycin?

Interferes with bacterial cell wall synthesis Signup and view all the answers

What is the primary route of administration for Vancomycin?

Intravenous Signup and view all the answers

Which of the following antibiotics is derived from Streptomyces orientalis?

Vancomycin Signup and view all the answers

What is the spectrum of activity of Polymyxin B and Colistin?

G(-) bacteria Signup and view all the answers

What is the mechanism of action of Mupirocin?

Reversibly binds to isoleucyl transfer-RNA synthetase Signup and view all the answers

What is the primary use of Mupirocin?

Topical use Signup and view all the answers

What is the adverse effect associated with Vancomycin's 'Red Man or Red Neck Syndrome'?

Decreased auditory acuity Signup and view all the answers

Which of the following antibiotics is derived from Pseudomonas fluorescens?

Mupirocin Signup and view all the answers

Study Notes

Cephalosporins

Structure: consist of a six-membered dihydrothiazine ring fused to a beta lactam ring
Broad spectrum and resistant to beta lactamase inactivation
Classified into generations, each with its own spectrum of activity:
- 1st Generation: excellent gram-positive and modest gram-negative activity, alternatives for skin and soft-tissue infections, and for streptococcal pharyngitis
- 2nd Generation: better activity against gram-negative organisms with some gram-positive action, treats URTI, LRTI, sinusitis, and otitis media
- 3rd Generation: activity against gram-positive organisms and much more activity against Enterobacteriaceae
- 4th Generation: encompasses the antimicrobial spectrum of all the third-generation agents and has increased stability to hydrolysis by inducible chromosomal -lactamases

Carbapenems

Comprise a family of fused beta lactam rings
Has broadest antimicrobial spectrum of any antibiotic
Analogues of penicillins or clavams, the sulfur or oxygen being replaced with carbon
Examples: Olivanic acids, Thienamycin, Imipenem, Meropenem, Ertapenem

Aminoglycosides

Natural products or semi-synthetic derivatives of compounds produced by a variety of soil actinomycetes
Mechanism of Action: binds to 30s ribosomal subunit and interferes with initiation of protein synthesis
Examples: Streptomycin, Tobramycin, Neomycin, Spectinomycin, Netilmicin, Amikacin

Macrolides

Contain a many-membered lactone ring (14-membered ring: Erythromycin and Clarithromycin, 15-membered ring: Azithromycin)
Basic in nature due to the presence of a glycosidically linked amino sugar
Spectrum of Activity: resembles that of Penicillin, used as an alternative to PCN
Examples: Erythromycin, Clarithromycin, Azithromycin

Chloramphenicol

Produced from Streptomyces venezuelae
May cause blood dyscrasias
Contains a nitrobenzene moiety and is a derivative of dichloroacetic acid
Clindamycin: a congener of Lincomycin, improved absorption and distribution than Lincomycin

Monobactams

Binds with PBP3 in gram-negative bacteria only
Treats UTI, LRTI, intra-abdominal infection, gynecological infection, and septicemia
Examples: Aztreonam

Quinolones

Mechanism of Action: inhibition of Topoisomerase IV and DNA gyrase enzymes
Spectrum of Activity: specific agents with activity against Streptococci, active against Chlamydia, Mycoplasma, Legionella, Brucella, and Mycobacterium
Examples: Levofloxacin, Gatifloxacin, Moxifloxacin, Ofloxacin, Ciprofloxacin

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Description

This quiz covers the structure and classification of cephalosporins, a type of broad-spectrum antibiotic. Learn about their characteristics, generations, and uses in treating various infections.