In-vitro activities of cefamandole and cephalothin against 1,881 clinical isolates. A multi-center study

Area of Science:

• Microbiology
• Infectious Diseases
• Pharmacology

Background:

• Antibiotic resistance is a growing global health concern.
• Cephalosporins are a class of beta-lactam antibiotics widely used to treat bacterial infections.
• Evaluating the efficacy of existing antibiotics against contemporary clinical isolates is crucial.

Purpose of the Study:

• To compare the in vitro activity of cefamandole and cephalothin against a large collection of clinical bacterial isolates.
• To identify bacterial pathogens susceptible or resistant to these two cephalosporins.

Main Methods:

• Agar dilution technique was employed for antimicrobial susceptibility testing.
• 1,881 clinical isolates from 18 bacterial genera were tested.
• Isolates were collected from five geographically distinct centers in the United States.

Main Results:

• The majority of bacterial isolates were susceptible to both cefamandole and cephalothin (MIC ≤ 8 µg/ml).
• Cefamandole exhibited greater antimicrobial activity against most tested bacterial pathogens.
• Enterococci, Serratia spp., and Acinetobacter spp. were resistant to both antibiotics.
• Cephalothin showed higher activity against Staphylococcus aureus.
• Both cephalosporins were largely inactive against methicillin-resistant Staphylococcus aureus (MRSA).
• Enterobacter spp. and indole-positive Proteus spp. were susceptible to cefamandole but resistant to cephalothin.

Conclusions:

• Cefamandole generally possesses broader in vitro activity than cephalothin against a diverse range of clinical bacterial isolates.
• Neither cefamandole nor cephalothin are effective against MRSA.
• Specific bacterial genera exhibit differential susceptibility patterns to cefamandole and cephalothin, informing empirical treatment choices.