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Class cephalosporins 2
 

Class cephalosporins 2

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    Class cephalosporins 2 Class cephalosporins 2 Presentation Transcript

    • CEPHALOSPORINS
    •  Cephalosporins were first isolated from cultures of Cephalosporium acremonium by Italian scientist Giuseppe Brotzu  They consists of dihydrothiazine ring fused to a β- lactam ring containing appropriate side chain at position -7  Obtained from Cephalosporinium acremonium
    •  First Generation  Cephalexin, Cefadroxil  Cephazolin  Second Generation  Cefuroxime  Cefaclor  Cefoxitin (cephamycin) Good activity  Staphs and Streps Increased activity  Gram negatives, Slightly less activity against Gram Positives
    •  Third Generation  Ceftriaxone,  Cefotaxime  Ceftazidime  Fourth Generation  Cefipime Very good Gram negative coverage Reasonable against Gram Positives Ceftazidime has anti-pseudomonal activity Very broad spectrum activity including Pseudomonas
    •  Cephalosporins are bactericidal and have the same mode of action as beta-lactam antibiotics. Cephalosporins disrupt the synthesis of the peptidoglycan layer of bacterial cell wall.  The peptidoglycan layer is important for cell wall structural integrity. The final transpeptidation step in the synthesis of the peptidoglycan is facilitated by transpeptidases known as pencillin binding proteins (PBPs).  β-lactam antibiotics mimic this site and competitively inhibit PBP cross linking of peptidoglycan. 6
    •  Cephazolin  Good activity v Streps & Penicillin Resistant Staphs.  Surgical prophylaxis for cardiac and vascular surgery, insertion of orthopaedic prostheses, H&N surgery and most gynaecological surgery.  Treatment of Soft tissue infections, particularly in the outpatient setting. (not for bite wounds as poor activity against anaerobes and Pasteurella) Cefadroxil
    •  Cefaclor, Cefuroxime  Cefoxitin, Cefotetan, -Increased activity  H. influenzae, M. catarrhalis. Used for Community Acquired Respiratory Tract Infections, Surgical prophylaxis for Colorectal Surgery. Treatment of post-operative wound infections. •Cefaclor •Oral, good against URTIs & UTIs. Moderate activity in Soft Tissue Infections.
    •  Against Gram Negative organisms  Cephalosporins with extended spectrum of activity against--Indole positive Proteus, Klebsiella, Moraxella catarrhalis, Neisseria species 9
    •  Apart from Aerobic infections, Cefoxitin and Cefotetan can be used to treat mixed anaerobic infections, including peritonitis, and diverticulitis  Cefoxitin and Cefotenan are useful as prophylaxis in colorectal surgeries, vaginal or abdominal hysterectomies and appendicitis , because of activity against B.fraglis. 10
    • Cefixime, Cefpodoxime, Cefdinir Ceftriaxone, Cefoperazone, Cefotaxime Good, broad spectrum Gram negative cover with reasonable Gram Positive coverLong half life, Good CSF penetration. Drug of choice suspected bacterial meningitis Relatively good  Penicillin Resistant Pneumococci Special indications- Treatment of N. gonorrhoeae, Chancroid, Lyme disease, Typhoid fever, Severe Shigella & Salmonella infections, Gram negative Brain abscess, endocarditis by HACEK organisms.
    • Ceftazidime-Activity v Pseudomonas also, but should not be used as Monotherapy for Pseudomonas infections. They have a broad spectrum of activity and further increased activity against Gram-negative organisms.  They may be particularly useful in treating hospital acquired infections  Extended-spectrum beta-lactamases are reducing the clinical utility of this class of antibiotics.  They are also able to penetrate the CNS, making them useful against meningitis caused by pneumococci, meningococci, H. influenzae, and susceptible E.coli. 12
    •  Cefozopran, Cefpirome, cefipime  Fourth-generation cephalosporins are extended- spectrum agents with similar activity against Gram- positive organisms as first-generation cephalosporins.  They also have a greater resistance to beta- lactamases than the third-generation cephalosporins.  Many can cross the blood-brain barrier and are effective in meningitis.  They are also used against Pseudomonas aeruginosa.
    •  Cefipime  Broad spectrum including Pseudomonas  Enhanced activity against certain Gram negative bacilli, including Enterobacter, Citrobacter and Serratia.  Uses. Severe Community Acquired Pneumonia requiring Intensive Care.
    • Cepftobiprole, Ceftaroline Ceftobiprole has been described as "fifth generation" though acceptance for this terminology is not universal. Ceftobiprole has powerful anti-pseudomonal characteristics and appears to be less susceptible to development of resistance. Ceftaroline is an injectable cephalosporin active against MRSA & penicillin resistant streptococcus pneumoniae It is inactive against Non fermenters & Carbapenemases producers. 15
    •  With exception of Cefipime, should not be used for treatment of Enterobacter, Serratia, Citrobacter infections due to induction of chromosomal Amp C beta-lactamases in these bacteria.  Not effective against Enterococci.
    •  Cefoperazone, Ceftazidime Cefpirome, Cefepime,Cefozopran, Ceftobipirole, Ceftaroline, ceftobiprole 17
    • i) Antibiotic Destruction by Beta-lactamases (Enterobacteraciae) ii) Alteration in the PBP target resulting in reduced binding affinity (MRSA, ) iii) Reduced penetration of the antibiotic through the membrane iv) Increased Efflux of the Drug
    •  Hypersensitivity  Coagulation abnormalities  Pseudolithiasis
    •  Carbapenems are: - β-lactams that contain a fused β-lactam ring and a 5-membered ring system that differs from the penicillins in being unsaturated (double bond between C-2 and C-3) and containing a carbon atom instead of the sulfur atom.  Imipenem is N-formimidoylthienamycin, the most stable derivatives of thienamycin.
    •  Meropenem is a second generation carbapenem.  Meropenem is not hydrolyzed by DHP-I and is resistant to most β-lactamases, including a few carbapenemases that hydrolyze carbapenem.  The lower incidence of nephrotoxicity of meropenem (compared with imipenem) has been correlated with its greater stability to DHP-I.
    •  Monobactams have a monocyclic β-lactam ring and are resistant to β-lactamases.  Aztreonam was isolated from Chromobacterium violaceum .  Aztreonam is the first clinically useful monobactam.  The antimicrobial activity of Aztreonam differs from those of other β-lactam antibiotics and more closely resembles that of an aminoglycosides in activity without the nephrotoxicity of aminoglycosides