Cefuroxime Susceptibility Testing 

Cefuroxime is a second-generation cephalosporin with activity against Gram-positive and Gram-negative bacteria, including Streptococcus pneumoniae, Haemophilus influenzae, and Enterobacterales. It is commonly used in the treatment of respiratory tract infections, urinary tract infections (UTIs), skin infections, and surgical prophylaxis. While cefuroxime is stable against some β-lactamases, it is susceptible to extended-spectrum β-lactamases (ESBLs) and carbapenemases, necessitating routine susceptibility testing.

Testing Methodologies

The susceptibility of cefuroxime is determined using Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines, employing the following methodologies:

• Etest (Gradient Strip) Method:
  • Utilizes a concentration gradient strip impregnated with cefuroxime.
  • Provides direct MIC determination, particularly useful for borderline-resistant strains.
• Automated Susceptibility Testing Systems:
  • Platforms such as VITEK 2, BD Phoenix, and Microscan determine cefuroxime MIC values.
  • May require confirmatory BMD testing for borderline-resistant isolates.

Application and Clinical Relevance

• Treatment of Gram-Positive and Gram-Negative Infections:
  • Cefuroxime is a key antibiotic for treating respiratory tract infections, UTIs, skin infections, and surgical prophylaxis.
  • Frequently used in empirical therapy for community-acquired infections.
• Detection and Monitoring of Resistance Mechanisms:
  • Resistance mechanisms include ESBL production (CTX-M, TEM, SHV), AmpC β-lactamases, and carbapenemases (KPC, NDM, OXA-48, VIM, IMP).
  • Confirmatory ESBL phenotypic testing (e.g., double-disk synergy test or combination disk tests) is essential.
• Surveillance and Resistance Trends:
  • Continuous susceptibility testing is crucial for monitoring emerging resistance patterns.
  • Helps optimize antimicrobial stewardship programs by preventing empirical overuse.

Cefuroxime susceptibility testing plays a critical role in diagnostic microbiology and infection control, particularly in community-acquired and MDR infections. Broth microdilution and disk diffusion methods remain primary approaches, while automated systems offer rapid assessment.