Cephalosporins were first isolated from cultures of
Cephalosporium acremonium by Italian scientist
They consists of dihydrothiazine ring fused to a β-
lactam ring containing appropriate side chain at
Staphs and Streps
Increased activity Gram
negatives, Slightly less activity
against Gram Positives
Very good Gram negative coverage
Reasonable against Gram Positives
Ceftazidime has anti-pseudomonal
Very broad spectrum activity
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
β-lactam antibiotics mimic this site and
competitively inhibit PBP cross linking of
Cephazolin, cefadroxil, Cefazolin
Good activity v Streps & Penicillin Resistant
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, salmonella,
pseudomonas, enterobacter and Pasteurella)
Cefaclor, Cefuroxime(BBB), Cefoxitin, Cefotetan,
Against Gram Negative organisms
Cephalosporins with extended spectrum of activity
against--Indole positive Proteus, Klebsiella,
Moraxella catarrhalis, Neisseria species
-Increased activity G-veH. influenzae, M.
P/K-stable against beta lactamases except for
Excreted unchanged through kidney (probenacid
Route- IM inj are painful, IV is better
Used for Community Acquired Respiratory Tract
Infections, Surgical prophylaxis for Colorectal
Surgery. Treatment of post-operative wound
Cefoxitin, cefotetan- anaerobes peritoniitis
Cefuroxime- CAP, prophylaxis in colorectal
surgeries, vaginal or abdominal
hysterectomies and appendicitis , because of
activity against B.fraglis.
•Cefaclor-Oral, good activity against URTIs & UTIs.
Moderate activity in soft tissue infections.
Cefixime, Cefpodoxime, Cefdinir, Ceftriaxone,
Good, broad spectrum Gram negative cover with
reasonable Gram Positive coverLong half life, Good
CSF penetration. Drug of choice suspected bacterial
Relatively good Penicillin Resistant Pneumococci
Special indications- Treatment of N. gonorrhoea,
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
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.
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.
Broad spectrum including Pseudomonas
Enhanced activity against certain Gram
negative bacilli, including Enterobacter,
Citrobacter and Serratia.
Uses. Severe Community Acquired Pneumonia
requiring Intensive Care.
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
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
Not effective against Enterococci.
i) Antibiotic Destruction by Beta-lactamases
ii) Alteration in the PBP target resulting in reduced
binding affinity (MRSA, )
iii) Reduced penetration of the antibiotic through the
iv) Increased Efflux of the Drug
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
Imipenem is N-form-imidoyl-thienamycin, the most
stable derivatives of thienamycin.
Meropenem is a second generation carbapenem.
Meropenem is not hydrolyzed by DHP-
I(DeHydroPeptidase-1) and is resistant to most β-
lactamases, including a few carbapenemases that
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
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