Cephalosporine

Cephalosporins, also known as cephalosporine in some languages, are a class of beta-lactam antibiotics derived from the fungus Acremonium chrysogenum (formerly Cephalosporium). They inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to cell lysis. They are bactericidal and typically show a spectrum that broadens with newer generations, combining good activity against gram-positive bacteria with increasing activity against gram-negative organisms and improved stability to certain beta-lactamases compared with early penicillins.

Generations provide different spectrums and properties. First-generation cephalosporins (for example, cephalexin, cefazolin) have strong gram-positive activity and modest gram-negative coverage. Second-generation agents (such as cefuroxime, cefaclor) offer better gram-negative activity. Third-generation cephalosporins (e.g., cefotaxime, ceftazidime) expand gram-negative coverage and often have greater tissue penetration with variable CNS penetration. Fourth-generation agents (such as cefepime) extend gram-negative activity, including Pseudomonas, and show greater beta-lactamase stability. Fifth-generation antibiotics (such as ceftaroline) retain broad gram-negative activity and are notable for activity against MRSA. Some cephalosporins are available for oral use, others only by injection; dosing depends on the agent, the infection, and renal function.

Resistance and safety: The main resistance mechanisms include beta-lactamase production and changes in penicillin-binding proteins. Adverse effects are generally mild to moderate and include rash, diarrhea, and gastrointestinal upset. Hypersensitivity reactions can occur, and there is some cross-reactivity with penicillin allergies, though the risk is lower than with many other beta-lactams. Cephalosporins can cause antibiotic-associated diarrhea and, rarely, severe colitis. Dose adjustments are often required in renal impairment, and pregnancy safety varies by compound but many cephalosporins are considered acceptable in pregnancy.