A 65-year-old man undergoes cystoscopy because of the presence of microscopic hematuria in order to rule out urologic malignancy. The patient has mild dysuria and pyuria and empirically receives oral therapy with cip-rofloxacin for presumed urinary tract infection prior to the procedure and tolerates the procedure well. Approxi-mately 48 hours after the procedure, the patient presents to the emergency department with confusion, dysuria and chills. Physical exam reveals a blood pressure of 90/50, pulse of 120, temperature of 38.5° C and respira-tory rate of 24. The patient is disoriented but the physical exam is otherwise unremarkable. Laboratory test shows WBC 24,000/mm3 and elevated serum lactate; urinalysis shows 300 WBC per high power field and 4+ bacteria. What possible organisms are likely to be responsible for the patient’s symptoms? At this point, what antibiotic(s) would you choose for initial therapy of this potentially life-threatening infection?
The development of antimicrobial drugs represents one of the most important advances in therapeutics, both in the control or cure of serious infections and in the prevention and treatment of infectious complications of other therapeutic modalities such as cancer chemotherapy, immunosuppression, and surgery. However, evidence is overwhelming that antimicrobial agents are vastly overprescribed in outpatient settings in the USA, and the availability of antimicrobial agents without prescription in many developing countries has—by facilitating the development of resistance—already severely limited therapeutic options in the treatment of life-threatening infections. Therefore, the clinician should first determine whether antimicrobial therapy is warranted for a given patient. The specific questions one should ask include the following: 1.
Is an antimicrobial agent indicated on the basis of clinical findings? Or is it prudent to wait until such clinical findings become apparent?
2.
Have appropriate clinical specimens been obtained to establish a microbiologic diagnosis?
3.
What are the likely etiologic agents for the patient’s illness?
4.
What measures should be taken to protect individuals exposed to the index case to prevent secondary cases, and what measures should be implemented to prevent further exposure?
5.
Is there clinical evidence (eg, from well-executed clinical trials) that antimicrobial therapy will confer clinical benefit for the patient?
Once a specific cause is identified based on specific microbiologic tests, the following further questions should be considered: 1.
If a specific microbial pathogen is identified, can a narrower-spectrum agent be substituted for the initial empiric drug?
2.
Is one agent or a combination of agents necessary?
3.
What are the optimal dose, route of administration, and duration of therapy?
4.
What specific tests (eg, susceptibility testing) should be undertaken to identify patients who will not respond to treatment?
5.
What adjunctive measures can be undertaken to eradicate the infection? For example, is surgery feasible for removal of devitalized tissue or foreign bodies—or drainage of an abscess—into which antimicrobial agents may be unable to penetrate? Is it possible to decrease the dosage of immunosuppressive therapy in patients who have undergone organ transplantation? Is it possible to reduce morbidity or mortality due to the infection by reducing host immunologic response to the infection (eg, by the use of corticosteroids for the treatment of severe Pneumocystis jiroveci pneumonia or meningitis due to Streptococcus pneumoniae)?