Antimicrobial therapy respiratory tract infections

Hitt CM, Nightingale CH, Quintiliani R, Nicolau DP. Streamlining antimicrobial therapy for lower respiratory tract infections. Clin Infect Dis 1997 24(suppl 2) S231-237. 

The proper route of administration for an antimicrobial depends on the site of infection. Parenteral therapy is warranted when patients are being treated for febrile neutropenia or deep-seated infections such as meningitis, endocarditis, and osteomyelitis. Severe pneumonia often is treated initially with intravenous antibiotics and switched to oral therapy as clinical improvement is evident. Patients treated in the ambulatory setting for upper respiratory tract infections (e.g., pharyngitis, bronchitis, sinusitis, and otitis media), lower respiratory tract infections, skin and soft tissue infections, uncomplicated urinary tract infections, and selected sexually transmitted diseases may receive oral therapy. 

Guay DRP. Short-course antimicrobial therapy of respiratory tract infections. Drugs 2003 63 2169-2184. 

The magnitude and duration of drug concentrations above MIC in respiratory secretions after aerosol administration indicate that mhalation therapy may be a suitable option for some bacterial infections of the lower respiratory tract. Pretreatment with a short-acting, aerosolized bronchodilator, such as albuterol sulfate, may improve the pulmonary distribution of aerosolized antimicrobial drugs. 

The search for useful inhaled antibiotics has been driven, in part, by a concern about the adequacy of systemic antimicrobial therapy for respiratory infections. Some agents, including aminoglycoside antibiotics, exhibit limited penetration into respiratory tract secretions. In fact, aminoglycosides may achieve sputum concentrations that are 12% of related serum concentrations. In addition, cystic fibrosis patients are often colonized with mucoid strains of Pseudomonas aeruginosa. This phenotype is associated with a further reduction in penetration of antibiotics. 

Drug therapy, particularly with broad spectrum antimicrobials or combinations of agents, can lead to alterations of the normal microbial flora of the upper respiratory, intestinal and genitourinary tracts, permitting the overgrowth of opportunistic organisms, especially fungi or resistant bacteria. These infections are often difficult to treat. 

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