Netilmicin, a new derivative of gentamicin c1a (c-1-n-ethyl-sisomicin); its in vitro activity against gram-negative bacilli and a case of infected bronchiectasis treated with the new drivative

Akira Watanabe, Seiichi Aonuma, Kikuo Onuma, Masako Sasaki, Kotaro Oizumi, Kiyoshi Konno

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    Minimal inhibitory concentrations (MICs) of Netilmicin against a total of 108 clinical isolates of gram negative bacilli were compared with those of the other aminoglycoside antibiotics available at present, those were, Gentamicin (GM), Dibekacin (DKB), Tobramycin (TOB) and Sisomicin (SISO). And therapeutic effect of netilmicin was observed on a patient with infected bronchiectasis. Of 28 isolates of E. coli examined, 18 (64%) were inhibited at 0.78 μg/ml or less of netilmicin, 19 (68%) at the same concentrations of sisomicin, 16 (57%) at those of gentamicin. Thus, it was apparent that the 3 drugs mentioned above possessed similar antimicrobial activities against E. coli. Dibekacin, tobramycin and amikacin revealed to be 2 to 4 fold less active against E. coli than netilmicin, sisomicin and gentamicin. More than 60 per cent of 28 tested strains of Klebsiella pneumoniae were inhibited at 0. 39 μg/ml or less of netilmicin and sisomicin. But 2 fold higher concentration of gentamicin was required to inhibit the same portion of the strains. Amikacin and dibekacin were shown to be less active against E. coli than netilmicin and sisomicin by 1 two-fold dilution, and than tobramycin by 2 two-fold dilutions. Of 8 clinical isolates of Serratia, 6 were inhibited at 6. 25 μg/ml or less of netilmicin and these concentrations were 4 times higher than those of gentamicin and sisomicin, and were nearly equal to those of dibekacin, tobramycin and amikacin. The MICs of netilmicin against 44 clinical isolates of Pseudomonas aeruginosa distributed widely from 1. 56 to over than 100 μg/ml, but 31 isolates (70%) were inhibited at concentrations ranging from 1. 56 to 6.25 (μg/ml of the drug. Against Pseudomonas, among aminoglycoside antibiotics tested, tobramycin, sisomicin, dibekacin and gentamicin were active, in the order mentioned, than netilmicin. Amikacin was slightly less active than netilmicin against Pseudomonas. A complete cross resistance was noted between netilmicin and gentamicin. But in contrast, most of clinical isolates of E. coli and Pseudomonas resistant to dibekacin or amikacin wete susceptible to netilmicin. About a half of strains of Klebsiella which were insensitive to dibekacin or amikacin were also sensitive to netilmicin. A patient, 46 year old female, with infected bronchiectasis was treated with netilmicin at a daily dose of 150 mg, divided twice, for 9 day. A favorable clinical response was obtained. The patient became afebrile by the evening of the day of the start of the treatment. Three days after cough and sputum disappeared. Immediately before the treatment, E. coli and H. influenzae had been cultured from the sputum. E. coli was eradicated from the sputum by the treatment. Since despite of persistence of H. influenzae marked decrease in the amount of the sputum was achieved, E. coli was assumed to be the causative organism. Thus, the bacteriological outcome with the netilmicin treatment was considered to be positive in this patient. No abnomality was detected in hepatic and renal function tests and in peripheral blood analysis which were performed at the end of the treatment. No auditory disturbance was proved by making a comparison of the audiograms taken before and after the treatment.

    Original languageEnglish
    Pages (from-to)108-118
    Number of pages11
    Publication statusPublished - 1981 Jan 1

    ASJC Scopus subject areas

    • Pharmacology (medical)
    • Infectious Diseases
    • Pharmacology
    • Drug Discovery
    • Oncology

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