[Parallel resistance between cephalosporins and penicillins]

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Beta-lactam antibiotics, including cephalosporins and penicillins, are crucial for treating bacterial infections.
• Emerging antibiotic resistance poses a significant threat to public health, necessitating an understanding of resistance mechanisms.
• Cross-resistance between different antibiotic classes can complicate treatment strategies.

Purpose of the Study:

• To investigate the induction of antibiotic resistance in key Gram-negative bacteria (Enterobacter, Klebsiella, Pseudomonas aeruginosa) against specific beta-lactam antibiotics.
• To determine the extent of cross-resistance between cephalosporins and penicillins following induced resistance.
• To evaluate the implications of these findings for clinical treatment guidelines.

Main Methods:

• Bacterial cultures of Enterobacter, Klebsiella, and Pseudomonas aeruginosa were subjected to 15 serial transfers at subinhibitory concentrations of cefotaxime, cefoperazone, mezlocillin, azlocillin, and piperacillin.
• Minimum Inhibitory Concentrations (MICs) for these five beta-lactam antibiotics were determined before and after resistance induction.
• Homologous and cross-resistance patterns were analyzed to quantify resistance development.

Main Results:

• Significant homologous resistance was induced by cefotaxime in Enterobacter (2021-fold) and Pseudomonas aeruginosa (42.2-fold), and by cefoperazone in Klebsiella (64-fold).
• Lower levels of homologous resistance were observed with cefoperazone in Ps. aeruginosa (9.9-fold) and mezlocillin in Enterobacter (10.6-fold) and Klebsiella (4.6-fold).
• Cephalosporin-induced resistance frequently conferred cross-resistance to penicillins, particularly in Ps. aeruginosa and Enterobacter, while penicillin-induced resistance to cephalosporins was rare.

Conclusions:

• The uncritical use of cephalosporins can potentially lead to broad resistance against beta-lactam antibiotics, including penicillins.
• Cross-resistance patterns suggest that cephalosporin therapy may compromise the efficacy of penicillin-based treatments.
• Acylureidopenicillins should be considered the preferred choice for initial management of emergency cases due to potential cross-resistance issues with cephalosporins.