Choosing the right antibiotic

BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7214.919a (Published 02 October 1999) Cite this as: BMJ 1999;319:919

Right drug at right time in right dose saves lives

  1. David Bihari, associate professor (dbihari{at}enternet.com.au)
  1. Intensive Care Unit, St George Hospital, Sydney NSW 2217
  2. Department of Microbiology, General Infirmary and University of Leeds, Leeds LS1 3EX

    EDITOR—Leibovici et al make a fundamental point about the prescription of antimicrobial drugs—the right antibiotic at the right time saves lives1—and we should not forget it. Yet as the various commentators point out, it is not always easy to choose the right antimicrobial since we know that all drugs have side effects, some are expensive, and some are more poisonous than others.

    In intensive care, many patients present with septic shock, and we usually only get “one bite” at the cherry. I try to teach our residents a few of the “see-saw” principles of antimicrobial prescribing that I have learnt along the way.

    Firstly, the right drug in the right dose (big) at the right time does save lives. Surprisingly to some, antibiotics do work and you need to get it right from the start. Secondly, there is not much point in saving your “best” antibiotic for the postmortem room. Next, we treat patients, not fevers, white cell counts, chest radiographs, or cultures. But on the other hand, just because the laboratory cannot grow something does not mean that there are no germs there causing trouble. And it does not mean that you should not consult them. You should. Finally, try to avoid poisoning the patient but always remember (and keep telling the managers) that saving lives costs money. There is nothing cheaper than a quick death


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    Antibiotic choice may affect risk of Clostridium difficile infection

    1. Mark H Wilcox, senior lecturer (markwi{at}pathology.leeds.ac.uk),
    2. Jon Sandoe, specialist registrar
    1. Intensive Care Unit, St George Hospital, Sydney NSW 2217
    2. Department of Microbiology, General Infirmary and University of Leeds, Leeds LS1 3EX

      EDITOR—It is surprising that neither Leibovici et al nor the commentaries mention the issue of infection with Clostridium difficile induced by antibiotics when discussing the appropriateness of antimicrobial treatment of a severe urinary tract infection in a 83 year old man.1 Despite evidence of underreporting,2 notifications of C difficile continue to increase in England and Wales. Over 17 000 predominantly hospital acquired cases were reported to the Communicable Disease Surveillance Centre in 1998, 80% of which were in elderly people.

      Cephalosporins such as cefuroxime and cefotaxime have been widely cited as predisposing to C difficile infection. Leibovici et al consider cephalosporins but not fluoroquinolones such as ciprofloxacin or ureidopenicillins for the empirical treatment of severe sepsis. Aminoglycosides, fluoroquinolones, and ureidopenicillins have a lower propensity to induce C difficile infection.3 A prospective, crossover study in a geriatric ward found that empirical treatment with piperacillin-tazobactam was seven times less likely to induce C difficile infection than was treatment with cefotaxime.4

      The proportion of British hospitals reporting a change in antibiotic policies due to C difficile infection increased from 5% to 20% between 1993 and 1996.2 Elderly patients with nosocomial C difficile infection stay a median of three weeks longer in hospital, two weeks of which is spent in scarce isolation facilities, and a case-control study found an excess cost of over £4000 per case.5 Such costs dwarf those associated with buying antibiotics and cannot be ignored in cost effectiveness analyses of antimicrobial treatment.

      Care must be taken when extrapolating average gains in studies to specific patients. Leibovici et al1 refer to data derived from patients with a median age of 72 years and hospital or community acquired bacteraemia or fungaemia. Outcome in an 82 year old man with community acquired urinary tract infection may well differ from these findings. The authors also give antibiotic susceptibility rates for bacteraemic isolates, which include community and hospital pathogens, thus biasing towards resistant strains. Presumably, the figure of 77% susceptibility to gentamicin includes Gram positive and Gram negative isolates; community acquired Gram negative isolates are likely to be more susceptible to gentamicin. Once daily gentamicin may be associated with lower nephrotoxicity and in combination with ampicillin would be a potential therapeutic choice.

      The choice of antibiotic is complex. Workable antibiotic policies should aim to guide optimal treatment but will inevitably contain compromises and assumptions, not least because locally applicable and patient specific data are rarely available. Although “appropriate” antimicrobial treatment is a laudable goal, side effects cannot be relegated to secondary considerations.


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