Thein vitroactivity of Sisomicin, a new antibiotic derived fromMicromonospora inyoensis, was studied on clinically isolated bacteria. Serum levels and urinary excretion after intramuscular administration, tissue concentration in rats and therapeutic effectiveness were also investigated.
1) Antibacterial activity: Sisomicinis one of the most potent antibiotics, as active as Tobramycin, againstPseudomonas aeruginosaandProteussp.
2) Serum level and urinary excretion (man): Peak serum levels reached 5.9 pg/ml one hour after intramuscular administration of 40mg. Approximately 68.5% was excreted in the urine within 6 hours.
3) Organ distribution (rats): Highest tissue concentrations after intramuscular administration were found in the kidneys, followed by blood, lungs, spleen and muscles. The concentration in the liver was lower than that in other organs. The distribution pattern is similar to that of other aminoglycoside antibiotics.
4) Clinical trials: Ten patients received 12 courses of Sisomicin intramuscularly. Good response was obtained in 6 out of 7 patients with urinary tract infections, in 2 out of 4 with respiratory tract infections, and in 1 out of 1 with decubital infection. Causative pathogens were eliminated in 3 out of 4 E. coli, 2 out of 4Pseudomonas aeruginosa, one each ofEnterococcus, Klebsiella, H.influenzae and one Proteus/E. colimixed infections.
Itching was reported by one patient. Another patient with leukemia had elevation of S-GOT and S-GPT values. A definite connection with Sisomicin administration is not possible.
