Most respiratory tract infections are caused by viruses. Bacterial respiratory tract infections are usually treated empirically with antibiotic therapy that targets the most probable causative pathogens. Recommended antibiotic regimens for outpatient treatment of some common respiratory tract infections are listed in Table 1 for adults and Table 2 for children.

The text that follows reviews some common bacterial infections and their empiric treatment pending the results of culture and susceptibility testing. The recommendations made here are based on the results of susceptibility studies, clinical trials, and the opinions of Medical Letter reviewers. Tables 1 and 2 list the usual dosages of antibacterial drugs.

The FDA has approved pivmecillinam (Pivya – Utility Therapeutics), an oral penicillin-class antibacterial drug, for treatment of uncomplicated urinary tract infections (uUTIs) caused by susceptible isolates of Escherichia coli, Proteus mirabilis, or Staphylococcus saprophyticus in adult females. Pivmecillinam was approved by the FDA in 2024 but only recently became available in the US. It has been used in Europe for over 40 years.