Correspondence Acknowledgements The work was supported by grants from the Association for Spina Bifida and Hydrocephalus and the 'RICHARD' Fund, Sheffield.
The culture medium employed for determination of the minimum inhibitory concentration (MIC) was Middlebrook 7H10 agar (Difco), adjusting its pH 71 with a 1 Msodium hydroxide solution after the addition of Bacto OADC (Difco). Dilutions of the antibiotic were added to the culture medium in appropriate quantities to obtain concentrations ranging from 0-1 ug/ ml to 9 ug/ml. All strains were incubated for seven days in Middlebrook 7H 9 broth (Difco) and were shaken in a vorter-mixer for a few seconds daily. Prior to testing these cultures were adjusted to the McFarland No. 1 scale, and then diluted 1 : 1000. The inoculum was 0-1 ml of this dilution; tubes without antibiotic were seeded as controls. Incubation was at 37°C for 30 days. The MIC was taken as the lowest concentration of the antibiotic which inhibited bacterial growth. Amikacin showed activity against all the strains studied (Table I). Seventy-five per cent of them were inhibited by 1-1 ug/ml and 100% by 9 ug/ml.
References Annear, D. I. The effect of temperature on resistance of Staphylococcus aweus to mcihicillin and some other antibiotics. Medical Journal of Australia 1:444-6 (1968). Barber, M. Naturally-occurring methicillinresistant staphylococci. Journal of General Microbiology 35: 183-90 (1964). Bayston, R. The use of polyvinylpyrrolidone in the testing of staphylococci for sensitivity to methidllin and cephradine. Journal of Clinical Pathology. In press (1978). Churcher, G. M. A screening test for the detection of methicillin-resistant staphylococci. Journal of Clinical Pathology 21: 213-7 (1968). Greenwood, D. & O'Grady, F. The effect of osmolality on the response of Escherichia coli and Proteus mirabilis to penicillins. British Table L Distribution of the MICs of amikacin Journal of Experimental Pathology 53: 457-64 against M. tuberculosis (1972). Drug Greenwood, D. & O'Grady, F. Comparison of No. of strains Cumulative concentration responses of Escherichia coli and Proteus inhibited percentage (ug/ml) mirabilis to seven |J-lactam antibiotics. Journal of Infectious Diseases 128: 211-22 (1973). 01 0 0 Greenwood, D. & O'Grady, F. The comparative 0 0 0-2 performance of P-lactam antibiotics against 0-5 0 0 ampicillin-sensitive Escherichia coli in condi11 30 75 tions simulating those of the infected urinary 2-2 38 95 bladder. British Journal of Experimental Path4-5 38 95 ology 55: 245-9 (1974). 40 100 9 Naylor, P. G. D. A simple medium which controls the swarming of proteus. Journal of Medical Laboratory Technology 17: 184-6 (1960). Since the serum levels obtained with amikacin (Kirby et al., 1974) are higher than these in vitro MICs, its use in antituberculous Activity of amikacin against Mycobacterbun therapy may be justified, especially in patients tuberculosis infected with multiresistant strains. Sir, J. A. GARCIA RODRIGUEZ The activity of some aminoglycosides, streptoF . MARTIN LUENGO mycin and kanamycirj, against Mycobacterium M. C. SAENZ GONZALEZ tuberculosis has led us to investigate Department of Microbiology, the activity of amikacin, a semisynthetic School of Medicine, aminoglycoside elaborated by Kawaguchi, Salamanca, Spain Naito, Nakagawa & Fujisawak (1972). Martin Luengo et al. (1977) studied the References activity of amikacin against various species of Kawaguchi, H., Naito, T., Nakagawa, S. & mycobacteria other than M. tuberculosis and Fujisawak, N. BB-K8 a new semisynthetic we now report its activity against 40 recent aminoglycoside antibiotic. Journal of Antiisolates of M. tuberculosis. biotics {Tokyo) 25: 695-708 (1972).
Downloaded from http://jac.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on March 17, 2015
R. BAYSTON Department of Paediatrics, University of Sheffield, Children's Hospital, Sheffield S10 2TH, England
293
The culture medium employed for determination of the minimum inhibitory concentration (MIC) was Middlebrook 7H10 agar (Difco), adjusting its pH 71 with a 1 Msodium hydroxide solution after the addition of Bacto OADC (Difco). Dilutions of the antibiotic were added to the culture medium in appropriate quantities to obtain concentrations ranging from 0-1 ug/ ml to 9 ug/ml. All strains were incubated for seven days in Middlebrook 7H 9 broth (Difco) and were shaken in a vorter-mixer for a few seconds daily. Prior to testing these cultures were adjusted to the McFarland No. 1 scale, and then diluted 1 : 1000. The inoculum was 0-1 ml of this dilution; tubes without antibiotic were seeded as controls. Incubation was at 37°C for 30 days. The MIC was taken as the lowest concentration of the antibiotic which inhibited bacterial growth. Amikacin showed activity against all the strains studied (Table I). Seventy-five per cent of them were inhibited by 1-1 ug/ml and 100% by 9 ug/ml.
References Annear, D. I. The effect of temperature on resistance of Staphylococcus aweus to mcihicillin and some other antibiotics. Medical Journal of Australia 1:444-6 (1968). Barber, M. Naturally-occurring methicillinresistant staphylococci. Journal of General Microbiology 35: 183-90 (1964). Bayston, R. The use of polyvinylpyrrolidone in the testing of staphylococci for sensitivity to methidllin and cephradine. Journal of Clinical Pathology. In press (1978). Churcher, G. M. A screening test for the detection of methicillin-resistant staphylococci. Journal of Clinical Pathology 21: 213-7 (1968). Greenwood, D. & O'Grady, F. The effect of osmolality on the response of Escherichia coli and Proteus mirabilis to penicillins. British Table L Distribution of the MICs of amikacin Journal of Experimental Pathology 53: 457-64 against M. tuberculosis (1972). Drug Greenwood, D. & O'Grady, F. Comparison of No. of strains Cumulative concentration responses of Escherichia coli and Proteus inhibited percentage (ug/ml) mirabilis to seven |J-lactam antibiotics. Journal of Infectious Diseases 128: 211-22 (1973). 01 0 0 Greenwood, D. & O'Grady, F. The comparative 0 0 0-2 performance of P-lactam antibiotics against 0-5 0 0 ampicillin-sensitive Escherichia coli in condi11 30 75 tions simulating those of the infected urinary 2-2 38 95 bladder. British Journal of Experimental Path4-5 38 95 ology 55: 245-9 (1974). 40 100 9 Naylor, P. G. D. A simple medium which controls the swarming of proteus. Journal of Medical Laboratory Technology 17: 184-6 (1960). Since the serum levels obtained with amikacin (Kirby et al., 1974) are higher than these in vitro MICs, its use in antituberculous Activity of amikacin against Mycobacterbun therapy may be justified, especially in patients tuberculosis infected with multiresistant strains. Sir, J. A. GARCIA RODRIGUEZ The activity of some aminoglycosides, streptoF . MARTIN LUENGO mycin and kanamycirj, against Mycobacterium M. C. SAENZ GONZALEZ tuberculosis has led us to investigate Department of Microbiology, the activity of amikacin, a semisynthetic School of Medicine, aminoglycoside elaborated by Kawaguchi, Salamanca, Spain Naito, Nakagawa & Fujisawak (1972). Martin Luengo et al. (1977) studied the References activity of amikacin against various species of Kawaguchi, H., Naito, T., Nakagawa, S. & mycobacteria other than M. tuberculosis and Fujisawak, N. BB-K8 a new semisynthetic we now report its activity against 40 recent aminoglycoside antibiotic. Journal of Antiisolates of M. tuberculosis. biotics {Tokyo) 25: 695-708 (1972).
Downloaded from http://jac.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on March 17, 2015
R. BAYSTON Department of Paediatrics, University of Sheffield, Children's Hospital, Sheffield S10 2TH, England
293
