Mezlocillin, at a dose of 3 g intravenously over a 2-h period every 4 h, was used for the treatment of 92 episodes of documented
infections in 75 myelosuppressed
cancer patients. The response rate in 59 evaluable
bacterial infections was 46%. Eight of 23 patients with
septicemia (35%) responded. The response rates for Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli, the three most common gram-negative
infections, were 42, 64, and 70%, respectively.
Mezlocillin was well tolerated; the only toxicity attributable to this
antibiotic was a
skin rash in one patient. The formation of a false-positive urine
protein reaction by
mezlocillin was noted. This study demonstrated that
mezlocillin administered as a single agent was effective against some
infections in myelosuppressed
cancer patients. The response rate for Klebsiella sp.
infections was especially encouraging. However, because it had limited or little activity against many
infections, especially those caused by P. aeruginosa and Staphylococcus aureus, the general use of
mezlocillin as a single agent for treatment of
infections in immunocompromised
cancer patients cannot be recommended.