Cephalosporins are a group of β-lactam antibiotics that contain a cephalosporin ring nucleus. They are structurally and mechanistically similar to penicillin but have a more broad spectrum of antimicrobial activity. Cephalosporins were first discovered in 1948 from Cephalosporium acremonium mold found to have antibacterial properties. This discovery marked a significant advancement in the treatment of bacterial infections.
Mechanism of Action Like penicillin, cephalosporins work by inhibiting the synthesis of peptidoglycan cell walls in bacteria. Peptidoglycan provides structural integrity to bacterial cells and its inhibition prevents further cell growth and division. Cephalosporins bind irreversibly to penicillin-binding proteins (PBPs) in bacterial cells, thereby blocking the last step of cell wall biosynthesis. This damages the cell wall and causes osmotic lysis of bacteria as they are unable to withstand internal turgor pressure.
Spectrum of Activity Cephalosporins Drugs display bactericidal activity against both Gram-positive and Gram-negative bacteria. Their spectrum of coverage is generally broader than penicillin, with some cephalosporins effective against a wider range including anaerobic and select Gram-negative organisms. Early generation cephalosporins (Cefazolin, Cephalexin) are effective against streptococci, staphylococci. 2nd/3rd generation (Cefuroxime, Cefotaxime) add coverage of E. coli, Proteus, Klebsiella pneumoniae. 4th generation (Cefepime) cover Pseudomonas aeruginosa. Anti-anaerobic activity increases with each generation.
Adverse Effects Similar to penicillins, cephalosporins are generally well-tolerated. Common side effects include diarrhea, nausea, rashes, vomiting. By inhibiting peptidoglycan synthesis, they can potentially induce hypersensitivity reactions. Some individuals may develop an allergic reaction to one cephalosporin and cross-react to others due to similarity in R-group side chain. Incidence of hypersensitivity is low (<1%) but risk is higher among people with history of immediate penicillin allergy. Other rare side effects like anemia, leukopenia have also been reported.
Clinical Uses of Cephalosporins Due to broad-spectrum activity, good oral availability and tolerability, cephalosporins are extensively used for treating community-acquired and nosocomial infections: - Respiratory tract infections - pneumonia, bronchitis, otitis media, sinusitis - Skin and soft tissue infections - cellulitis, abscesses, wound infections, surgical prophylaxis - Urinary tract infections - cystitis, pyelonephritis - Gonorrhea, meningitis, pelvic inflammatory disease - Infective endocarditis caused by susceptible bacteria Their availability in both oral and injectable forms makes cephalosporins vital empirical therapy for many bacterial infections worldwide. Proper diagnostic testing should then guide continued therapy or switch to more targeted antibiotics.
Trends in Resistance Like other antibiotics, overuse and misuse of cephalosporins has contributed to emerging resistance in pathogenic bacteria. Extended spectrum β-lactamases (ESBLs) in E. coli and Klebsiella confer resistance to penicillins, early cephalosporins and aztreonam.
Carbapenemases make Pseudomonas and Enterobacteriaceae resistant even to last resort carbapenems. Multi-drug resistant Acinetobacter species have also emerged globally. Studies show most resistance mediated by transmissible plasmids and gene cassettes on integrons which facilitate horizontal spread of resistance.
Prudent use of cephalosporins through antimicrobial stewardship programs along with infection prevention strategies is needed to preserve their efficacy. Since their discovery in 1948, cephalosporins have revolutionized treatment of infectious diseases. Their simpler chemistry and targeted spectrum have made them hugely successful life-saving antibiotics.
While resistance threatens their long-term utility, new generations of cephalosporins with activity against resistant organisms are continually being developed. Along with antimicrobial stewardship, this ensures cephalosporins will continue protecting global health for many more years. As versatile and well-tolerated antibiotics, cephalosporins will remain pillars of empiric therapy against many life-threatening bacterial infections for the foreseeable future.
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Priya Pandey is a dynamic and passionate editor with over three years of expertise in content editing and proofreading. Holding a bachelor's degree in biotechnology, Priya has a knack for making the content engaging. Her diverse portfolio includes editing documents across different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. Priya's meticulous attention to detail and commitment to excellence make her an invaluable asset in the world of content creation and refinement.
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