Journal of Antimicrobial Chemotherapy (1990) 25, 697-724
Correspondence Antibiotic resistance in i
Benzylpenicfllin doses as weights ratber than milts
Regional Infectious Disease Unit, Fazakerley Hospital, Longmoor Lane, Liverpool L9 7AL, UK References British Medical Association and Royal Pharmaceutical Society of Great Britain (1989). British National Formulary 18, 202. Pharmaceutical Press, London. Thin, R. N. (1989). Treatment of venereal gyphiHs. Journal of Antimicrobial Chemotherapy 24, 481—3.
Editor-in-Chiefs note. We accept the rebuke and will try to ensure expression of penicillin doses by weight in future.
Sir, In a recent leading article, Dr David Greenwood (1989) mentions that enterococci are ordinarily resistant to cephalosporins except cefathiamidine. This was the first cephalosporin to show activity against enterococci (Tai et al., 1979). Chen & Williams (1983) found that all SS clinical isolates of Enterococcus faecalis that they tested were susceptible to cefathiamidine, but the two clinical isolates of E.faecium tested were resistant As E.faecium infections are often difficult to treat, cefathiamidine would be a useful agent if any strains were sensitive. I have measured the MIC of cefathiamidine and ten other antibiotics for 18 clinical isolates of E.faecium and the reference strain NCTC 7171. The MICs were determined by an agar-incorporation method with serial twofold dilutions of test antibiotics in Iso-sensitest agar. A multipoint inoculator was used to deposit an inoculum of 104 ctu. Table I shows the distribution of the MICs of the different antibiotics. All 18 clinical isolates were resistant to every /Mactam antibiotic tested, including cefathiamidine, although the NCTC 7171 strain was more sensitive to these agents. Peak serum concentrations after 500 mg cefathiamidine were 38-8 mg/1 (iv) and 26-2 mg/1 (im), in the investigation of Tai et al. (1979). In my study, vancomycin was the only agent with an MIC low enough for it to be effective in systemic infections but tiprofloxacin appears to have enough activity to warrant its use in simple urinary tract infections. R. J. SPRINGBETT Microbiology Laboratory, District General Hospital, Eastbourne, BN212VD, UK References Chen, H. Y. & Williams, J. D. (1983). The killing effects of cefathiamidine or ampirilHn alone and in combination with gentamkin against enterococci. Journal of Antimicrobial Chemotherapy 12, 19-26.
697
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on March 10, 2015
Sir, We enjoyed reading the recent editorial on the subject of the treatment of venereal syphilis (Thin, 1989). However, we are surprised that the Journal has published an editorial in which doses of penicillins are given only in international units. The current edition of the British National Formulary states 'International Units are no longer used for penicillins and all doses are stated in milligrams' (British Medical Association and Royal Pharmaceutical Society, 1989). Perpetuation of both dose formats causes confusion, particularly where penicillin combinations or benzathine penicillin are prescribed. We have recently seen problems arise after prescription of parenteral benzylpenicillin by junior medical staff, mistakenly writing gram doses as equivalent to mega unit doses—e.g., 3g 4hourly instead of 3 mega units (1-8 g) 4-hourly. The Journal and other leading international journals would do much to promote standardization by publishing penicillin doses in mg or g format. The equivalent dose in mega units might reasonably be added in brackets to assist prescribers who were reared on the traditional dosage system. N. J. BEECKTNG F. J. NYE
Correspondence Antibiotic resistance in i
Benzylpenicfllin doses as weights ratber than milts
Regional Infectious Disease Unit, Fazakerley Hospital, Longmoor Lane, Liverpool L9 7AL, UK References British Medical Association and Royal Pharmaceutical Society of Great Britain (1989). British National Formulary 18, 202. Pharmaceutical Press, London. Thin, R. N. (1989). Treatment of venereal gyphiHs. Journal of Antimicrobial Chemotherapy 24, 481—3.
Editor-in-Chiefs note. We accept the rebuke and will try to ensure expression of penicillin doses by weight in future.
Sir, In a recent leading article, Dr David Greenwood (1989) mentions that enterococci are ordinarily resistant to cephalosporins except cefathiamidine. This was the first cephalosporin to show activity against enterococci (Tai et al., 1979). Chen & Williams (1983) found that all SS clinical isolates of Enterococcus faecalis that they tested were susceptible to cefathiamidine, but the two clinical isolates of E.faecium tested were resistant As E.faecium infections are often difficult to treat, cefathiamidine would be a useful agent if any strains were sensitive. I have measured the MIC of cefathiamidine and ten other antibiotics for 18 clinical isolates of E.faecium and the reference strain NCTC 7171. The MICs were determined by an agar-incorporation method with serial twofold dilutions of test antibiotics in Iso-sensitest agar. A multipoint inoculator was used to deposit an inoculum of 104 ctu. Table I shows the distribution of the MICs of the different antibiotics. All 18 clinical isolates were resistant to every /Mactam antibiotic tested, including cefathiamidine, although the NCTC 7171 strain was more sensitive to these agents. Peak serum concentrations after 500 mg cefathiamidine were 38-8 mg/1 (iv) and 26-2 mg/1 (im), in the investigation of Tai et al. (1979). In my study, vancomycin was the only agent with an MIC low enough for it to be effective in systemic infections but tiprofloxacin appears to have enough activity to warrant its use in simple urinary tract infections. R. J. SPRINGBETT Microbiology Laboratory, District General Hospital, Eastbourne, BN212VD, UK References Chen, H. Y. & Williams, J. D. (1983). The killing effects of cefathiamidine or ampirilHn alone and in combination with gentamkin against enterococci. Journal of Antimicrobial Chemotherapy 12, 19-26.
697
Downloaded from http://jac.oxfordjournals.org/ at University of California, San Francisco on March 10, 2015
Sir, We enjoyed reading the recent editorial on the subject of the treatment of venereal syphilis (Thin, 1989). However, we are surprised that the Journal has published an editorial in which doses of penicillins are given only in international units. The current edition of the British National Formulary states 'International Units are no longer used for penicillins and all doses are stated in milligrams' (British Medical Association and Royal Pharmaceutical Society, 1989). Perpetuation of both dose formats causes confusion, particularly where penicillin combinations or benzathine penicillin are prescribed. We have recently seen problems arise after prescription of parenteral benzylpenicillin by junior medical staff, mistakenly writing gram doses as equivalent to mega unit doses—e.g., 3g 4hourly instead of 3 mega units (1-8 g) 4-hourly. The Journal and other leading international journals would do much to promote standardization by publishing penicillin doses in mg or g format. The equivalent dose in mega units might reasonably be added in brackets to assist prescribers who were reared on the traditional dosage system. N. J. BEECKTNG F. J. NYE
