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Fourth-Generation Cephalosporins

*Cephalosporina IV*

For medical students2 min readUpdated 2026-10-10

Fourth-generation cephalosporins are a group of broad-spectrum antibiotics that outperform earlier generations against both gram-positive and gram-negative microorganisms. These agents are administered parenterally to treat severe nosocomial infections.

RepresentativesCefepime and cefpirome

Route of administrationParenteral only (IM, IV)

Spectrum of activityHigh activity against *Pseudomonas aeruginosa*

ResistanceResistant to beta-lactamases

Spectrum of Activity

Antibiotics in this group feature an exceptionally broad spectrum of antimicrobial activity. Compared to previous generations, they demonstrate higher efficacy against Gram-positive cocci.

Key features of the spectrum:

High resistance to the destructive action of bacterial $\beta$-lactamases.
Pronounced activity against Pseudomonas aeruginosa among Gram-negative flora.

Pharmacokinetics

These drugs are administered exclusively via the parenteral route—intramuscularly or intravenously—with a dosing frequency of 2 to 3 times per day.

Distribution: The drugs penetrate various body tissues and organs exceptionally well.
Blood-Brain Barrier (BBB): They successfully cross the blood-brain barrier.
Elimination: Excreted unchanged by the kidneys.

Indications for Use

Due to their potent pharmacological properties, these agents are prescribed in the most complex clinical scenarios:

Severe nosocomial (hospital-acquired) infections caused by multidrug-resistant microorganisms.
Lower respiratory tract pathologies, including pneumonia, lung abscess, and pleural empyema.
Infectious complications in immunocompromised and neutropenic patients.

Side Effects

Like other members of this class, these antibiotics can cause several adverse reactions:

Allergic reactions: Urticaria, fever, serum sickness, and anaphylactic shock. Cross-allergy must be considered: if a patient is allergic to penicillins, cephalosporins are contraindicated.
Organ and systemic toxicity: Hepatic dysfunction, leukopenia, and seizures are possible.
Gastrointestinal tract and dysbiosis: Risk of superinfection, pseudomembranous colitis, oral candidiasis, and diarrhea.
Local reactions: Phlebitis associated with intravenous administration.

Mnemonic

Generation IV is heavy artillery: broad coverage against both Gram-positive organisms and Pseudomonas aeruginosa for severe hospital-acquired infections.

Frequently asked questions

What is the mechanism of action of fourth-generation cephalosporins?

The mechanism of action of fourth-generation cephalosporins, like other $\beta$-lactam antibiotics, is bactericidal and based on the inhibition of cell wall synthesis. These drugs bind to specific penicillin-binding proteins (PBPs) and inhibit the enzyme transpeptidase. This disrupts the formation of peptidoglycan, the primary component of the bacterial cell wall. As a result, structural integrity is compromised, and cell wall precursors accumulate inside the cell. This triggers autolytic enzyme systems and autolysins that degrade peptidoglycan, ultimately leading to lysis and death of the bacterial cell.

Which Gram-negative pathogens are susceptible to fourth-generation cephalosporins?

Fourth-generation cephalosporins show high activity against several Gram-negative bacteria.

Pseudomonas aeruginosa (Pseudomonas aeruginosa) — these drugs are highly effective against this pathogen, making them suitable for treating severe hospital-acquired infections and for empirical therapy in neutropenia.

They also target certain other Gram-negative microorganisms.

How do fourth-generation cephalosporins fundamentally differ from third-generation agents?

Fourth-generation cephalosporins differ from third-generation drugs by having an even broader spectrum of activity and enhanced efficacy against Gram-positive microorganisms.

Characteristic	Third Generation	Fourth Generation
Spectrum of activity	Pronounced activity against Gram-negative flora	Broader spectrum, balanced dual-coverage action
Gram-positive flora	Less active	Higher efficacy against Gram-positive cocci
Gram-negative flora	High activity	Covers Gram-negative bacteria including Pseudomonas aeruginosa

Both generations exhibit high resistance to degradation by bacterial $\beta$-lactamases.

What drugs are combined with fourth-generation cephalosporins to treat anaerobic infections?

Combination therapy involving fourth-generation cephalosporins, specifically cefepime with metronidazole, is used for moderate to severe acute cholecystitis.

What are the main representatives of fourth-generation cephalosporins?

This group includes cefepime and cefpirome.

What are the elimination features of these antibiotics?

The drugs are excreted unchanged by the kidneys.

Can cephalosporins be prescribed to patients with a penicillin allergy?

No, due to the risk of cross-reactivity, cephalosporins are contraindicated in patients with a history of severe penicillin allergy.

Go deeper

Comparison of activity of 1st, 2nd, 3rd, and 4th generation cephalosporins against Gram-positive and Gram-negative flora
Mechanisms of bacterial resistance to $\beta$-lactamases
Clinical use of antibiotics in neutropenic and immunocompromised patients
Specific toxicity and side effects of cefotetan and cefoperazone (N-methylthiotetrazole side chain)
Development of pseudomembranous colitis and superinfections during antibiotic therapy