Cefsulodin is a third-generation cephalosporin antibiotic with specific activity against Pseudomonas aeruginosa. It has no significant activity against other Gram-negative bacteria and very limited activity against Gram-positive bacteria and anaerobic bacteria. Cefsulodin was first synthesized and patented by the Takeda Pharmaceutical Company in 1977. In 2002, Takeda stopped production of cefsulodin. Many years of low-stability cefsulodin production has led to a widespread reduction of laboratory and research uses. Current attempts (i.e. IDEXX Laboratories) of increasing purity and stability of cefsulodin center around recrystallization. Typically, the process entails: Cefsulodin is dissolved in an organic solvent, sodium ions, water, or any mixture thereof, then subsequently recrystallized through separation of the unwanted fraction. Recently, TOKU-E has found the main cause of cefsulodin instability stems from one key impurity in 7-aminocephalosporanic acid, a raw material used in the synthesis of cefsulodin. To produce high-purity, high-stability cefsulodin, TOKU-E uses industrial HPLC to remove significant quantities of this impurity in 7-ACA and thus produces ultrapure, ultrastable, and ultrapotent cefsulodin.^[1]

Cefuslodin is most commonly used in cefsulodin-irgasan-novobiocin agar to select for Yersinia microorganisms.^[2] This agar is most often used in water and beverage testing.

The following represents MIC susceptibility data for various P. aeruginosa strains.

• Pseudomonas aeruginosa PA13 (resistant strain): 32 μg/ml
• Pseudomonas aeruginosa (wild-type, susceptible): 4 – 8 μg/ml

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