Question 2d

A 65 year old man has been admitted to your Intensive Care Unit with a presumptive diagnosis of community acquired pneumonia. He is sedated, intubated and ventilated, and is haemodynamically stable.

(d) What factors would make you subsequently change from your initial choice of antibiotic therapy?

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College Answer

Altering initial format if other suspected pathogens (e.g. gentamycin and meropenem for Burkolderia; cotrimoxazole for Pneumocystis etc.). Allergies (become known or develop). Discover unexpected resistance pattern. Other organisms causative (eg. Mycobacterium TB). Develop nosocomial superinfection or develop resistance. Develop side effect related to drug (e.g. severe liver function abnormalities). Spectrum may be narrowed if specific organism


What factors would cause you to change your antibiotic choice?

  • historical evidence pointing to a specific pathogen
  • microbiological identification of the pathogen, their sensitivities and resistances
  • failure to improve clinically with fevers and rising inflammatory markers in spite of antibiotic therapy 48-72hrs after commencement of antibiotics
  • patient intolerance of empiric antibiotic therapy due to side-effects

A better-worded question can be found in Question 18 from the first paper of 2012; the college wants to know "What are the possible reasons for non-response to empiric treatment for patients treated for severe community acquired pneumonia?" 



Mandell, Lionel A., et al. "Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults." Clinical infectious diseases 44.Supplement 2 (2007): S27-S72.