text: Pneumocystis jirovecii pneumonia Trimethoprim/sulfamethoxazole (TMP/SMX) is the medicine most commonly used to prevent Pneumocystis jirovecii pneumonia (PCP) People who get Pneumocystis pneumonia have a medical condition that weakens their immune system, like HIV/AIDS, or take medicines (such as corticosteroids) that reduce the body's ability to fight bacterial and viral infections. People with HIV/AIDS are less likely to get Pneumocystis pneumonia as a result of antiretroviral therapy (ART). However, Pneumocystis pneumonia is still a substantial public health problem. Most of what is scientifically known about Pneumocystis pneumonia and its treatment comes from studying people with HIV/AIDS.
  Susceptibility
  Organisms against which trimethoprim/sulfamethoxazole can be effective include:
  Acinetobacter spp.
  Aeromonas spp.
  Alcaligenes/Achromobacter spp.
  Bartonella henselae
  Bordetella pertussis (pertussis)
  Brucella spp.
  Burkholderia cepacia
  Burkholderia mallei (glanders)
  Burkholderia pseudomallei (melioidosis)
  Chlamydia spp.
  Chryseobacterium meningosepticum
  Citrobacter spp.
  Enterobacter spp.
  Enterococcus spp.
  Escherichia coli
  Haemophilus spp.
  Hafnia alvei
  Kingella spp.
  Klebsiella granulomatis
  Klebsiella pneumoniae
  Legionella spp.
  Listeria monocytogenes (listeriosis)
  Moraxella catarrhalis
  Morganella morganii
  Mycobacterium tuberculosis (tuberculosis)
  Neisseria gonorrhoeae (gonorrhoea)
  Neisseria meningitidis (meningococcal disease)
  Nocardia spp.
  Plesiomonas shigelloides
  Pneumocystis jirovecii
  Proteus mirabilis
  Proteus vulgaris
  Providencia rettgeri
  Providencia stuartii
  Salmonella typhi (typhoid fever)
  Non-typhi (food poisoning) Salmonella
  Serratia spp.
  Shigella spp.
  Staphylococcus aureus
  Staphylococcus epidermidis
  Staphylococcus saprophyticus
  Stenotrophomonas maltophilia
  Streptococcus agalactiae
  Streptococcus pneumoniae
  Streptococcus pyogenes
  Streptococcus viridans
  Toxoplasma gondii (toxoplasmosis)
  Tropheryma whippelii (Whipple's disease)
  Vibrio cholerae (cholera)
  Yersinia enterocolitica
  Yersinia pestis (bubonic plague)
  Yersinia pseudotuberculosis
  The only notable nonsusceptible organisms are Pseudomonas aeruginosa, the mycoplasmae and Francisella tularensis (the causative organism of tularaemia).