Cephalosporins are a class of beta-lactam antibiotics that are structurally similar to penicillins. They are divided into generations based on their antimicrobial spectrum and resistance to beta-lactamases. Earlier generations are effective against gram-positive bacteria while later generations have activity against more gram-negative bacteria including Pseudomonas. Common side effects include diarrhea, hypersensitivity reactions, and drug interactions with aminoglycosides which have synergistic activity against Klebsiella. Cephalosporins are used to treat a variety of bacterial infections depending on the generation, including pneumonia, meningitis, skin infections, and UTIs.

1. Cephalosporins
Sanjaya Mani Dixit
Assistant Prof of Pharmacology

2. Beta lactam Structure
• Cephalosporins are B-lactam
antibiotics closely related both
structurally and functionally to
Penicillins.

3. B- Lactams--- Cephalosporins
• Beta-lactam antibiotics are among the most
commonly prescribed drugs, grouped together based
upon a shared structural feature, the beta-lactam
ring.
• Cephalosporins cover a broad range of organisms.
• They are generally well-tolerated, and are easy to
administer; thus, these agents are frequently used
beta-lactam drugs.

4. CEPHALOSPORINS
• From a fungus Cephalosporium acremonium
• Semi-synthetic Cephalosporins- from 7- Aminocephalosporanic acid.
- Gram (+ve) & Gram (-ve)
- More Resistant than PCNs to beta - lactamases
- Bactericidal - action similar to PCN’s
- Action - inhibits bacterial cell wall synthesis
- 4 groups (generations) - each effective against a
broader spectrum of bacteria
- about 10% of people allergic to PCN also to allergic to
cephalosporins
- IM & IV - onset = almost immediate

5. Classification and Spectrum of
Activity of Cephalosporins
• Divided into 5 major groups called
“Generations”
• Are divided into Generations based on
Chronological development
 Antimicrobial spectrum
 Resistance to beta-lactamase
 Potency

6. First Generation Second Generation Third Generation Fourth Generation
1960s 1980s 1990s
* Oral Agent
Cefadroxil * Cefaclor * Cefdinir Cefepime
Cefazolin Cefamandole Cefoperaxone
Cefelixin * Cefonicid Cefotaxime
Cephalothin Ceforanide Ceftazidime
Cephaprin Cefotetan Ceftibuten
Cephradine * Cefoxitin Ceftizoxime
Cefuroxime
moxalactam
Ceftriaxone
Cephalosporins
Fifth Generation
Ceftaroline
Ceftobiprole
Anti MRSA Cephs

7. Parenteral Oral
First generation Cephalothin
Cefazolin
Cephalexin
Cephradine
Second generation Cefuroxime
Cefoxitin
Cefaclor
Cefuroxime axetil
Third generation Cefotaxime
Ceftizoxime
Cefixime
Cefdinir
Fourth generation Cefepime
Cefpirome

8. First Generation Cephalosporins
Best activity against gram-positive aerobes, with
limited activity against a few gram-negative aerobes
Gram-positive Gram-negative
Methicilin-susc S. aureusE. coli
Penicillin-susc S. pneumoniae K. pneumoniae
Group A/B/C/Gstreptococci P. mirabilis
Viridans streptococci
Indicated for streptococcal pharyngitis ( e.g. cephalexin)
Cephalexin used for resp, GI, GU, bone, & joint infections
Commonly used ( eg. Cefazolin) as prophylacic for surgical procedures.

9. Second Generation Cephalosporins
Spectrum of Activity
Gram-positive Gram-negative
meth-susc S. aureus E. coli
pen-susc S. pneumoniae K. pneumoniae
Group A/B/C/G strepP. mirabilis
viridans streptococci H. influenzae
M. catarrhalis
Neisseria sp.

10. Second Generation Cephalosporins
Spectrum of Activity
The cephamycins (cefoxitin and cefotetan)
are the only 2nd generation cephalosporins
that have activity against anaerobes
Anaerobes
Bacteroides fragilis
Bacteroides fragilis group

11. Second Generation Cephalosporins
Cefoxitin active against bowel anaerobes (B. fragilis )
Cefuroxim active against H. influenzae, M. catarrhalis, S.
pneumoniae
Cefaclor active against H. influenzae, M. catarrhalis
&E.coli
Cefprozil- similar to cefaclor, c. axetil and augmentin-
Second Generations are used primarily for URTIs (acute
otitis media, sinusitis ) and Lower RTIs
(acute exacerbation of chronic bronchitis).

12. Third Generation Cephalosporins
Spectrum of Activity
• In general, are even less active against Gram
positive aerobes, but have greater activity
against Gram-negative aerobes, including the B-
lactamase producing strains.
• Ceftriaxone and cefotaxime have the best
activity against Gram-positive aerobes, including
pen-resistant S. pneumoniae

13. Third Generation Cephalosporins
Spectrum of Activity
Gram-negative aerobes
E. coli, K. pneumoniae, P. mirabilis
H. influenzae, M. catarrhalis, N. gonorrhoeae (including
beta-lactamase producing); N. meningitidis
Citrobacter sp., Enterobacter sp., Acinetobacter sp.
Morganella morganii, Serratia marcescens, Providencia
Pseudomonas aeruginosa (ceftazidime and cefoperazone)

14. Third Generation Cephalosporins
Ceftriaxone has long half-life . Not advised in
neonates (interferes with bilirubin metabolism )
Cefotaxime preferred in neonate ( does not
interfere with bilirubin metabolism )
Ceftazidime & Cefoperazone have excellent activity
against P. aeruginosa.
Cefixime has similar activity to amoxicillin &
cefaclor for actute otitis media

15. Fourth Generation Cephalosporins
• 4th generation cephalosporins for 2 reasons
 Extended spectrum of activity
 Gram-positives: similar to ceftriaxone
 Gram-negatives: similar to ceftazidime, including
Pseudomonas aeruginosa; also covers beta-lactamase
producing Enterobacter sp.
 Resist hydrolysis by -lactamases; poor inducer of
extended-spectrum  -lactamases
• Cefepime is currently available

16. Fourth Generation Cephalosporins
Cefipime
Active against Gram +ve bacteria > than
Cefazolin against S. pyogenes,
S.pneumoniae but lower against S. aureus.
Similar to cefotaxime against E. coli & K.
pneumoniae but < for P. aeruginosa.

17. Pharmacokinetics
• Some Cephalosporins may be given orally but most are
given parenterally (IM or IV).
• Widely distributed in the body like penicillins
• Third generation Cephs --Cefoperazone, Cefotaxime,
Ceftriaxone, and Ceftazidime also cross BBB and are DOC
for meningitis due to Gram-negative intestinal bacteria.
• Almost all are primally eliminated via the kidneys and are
actively secreted by the renal tubules. Cefoperazone and
ceftriaxone are eliminated through the biliary tract.

18. Uses:
• A cephalosporin with or without an aminoglycoside is
first-line treatment of Klebsiella.
• First generation cephalosporins are used for surgical
prophylaxis of wound infection.
• Third generation cephalosporins are used to treat
meningitis due to pneumococci, meningococci, and
Haemophillus influenza.
• Ceftriaxone is the drug of choice for treating beta-
lactamase producing Neisseria gonorrhea.

19. Uses:
–Septicaemia (e.g. cefuroxime, cefotaxime)
–Pneumonia caused by susceptible organisms
–Meningitis (e.g. ceftriaxone, cefotaxime)
–Biliary tract infection
–Urinary tract infection (especially in pregnancy
or in patients unresponsive to other drugs)
–Sinusitis (e.g. cefadroxil).

20. Adverse effects
• Hypersensitivity reactions -similar to -penicillins
• Diarrhea may occur with oral forms.
• Nephrotoxicity
• Intolerance to alcohol (Disulfiram like reaction) has been
reported. (cefotetan, cefoperazone)
• Superinfection.
• Hyperprothrombinemia, Thrombocytopenia, Platelet
dysfunction. Administration of vitamin K (10mg) twice a week
can prevent this.
• Especially seen with 3rd
generation cephlosporins which
eliminate the bacteria in intestinal tract that produce Vitamin K.

21. CEPHALOSPORINS

22. Drug interaction
• Cephalosporins demonstrate synergistic
activity when combined with an
aminoglycoside to treat Klebsiella.

23. Common Bacteria by Site of Infection
Mouth
Peptococcus
Peptostreptococcus
Actinomyces
Skin/Soft Tissue
S. aureus
S. pyogenes
S. epidermidis
Pasteurella
Bone and Joint
S. aureus
S. epidermidis
Streptococci
N. gonorrhoeae
Gram-negative rods
Abdomen
E. coli, Proteus
Klebsiella
Enterococcus
Bacteroides sp.
Urinary Tract
E. coli, Proteus
Klebsiella
Enterococcus
Staph saprophyticus
Upper Respiratory
S. pneumoniae
H. influenzae
M. catarrhalis
S. pyogenes
Lower Respiratory
Community
S. pneumoniae
H. influenzae
K. pneumoniae
Legionella pneumophila
Mycoplasma, Chlamydia
Lower Respiratory
Hospital
K. pneumoniae
P. aeruginosa
Enterobacter sp.
Serratia sp.
S. aureus
Meningitis
S. pneumoniae
N. meningitidis
H. influenza
Group B Strep
E. coli
Listeria

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