Antibiotics for Acute Bacterial Prostatitis: Which Agent, and for How Long?

Authors:
Eric A. Dietrich, PharmD, BCPS, and Kyle Davis, PharmD, BCPS

Citation:
Dietrich EA, Davis K. Antibiotics for acute bacterial prostatitis: which agent, and for how long? Consultant. 2017;57(9):564-565.

Acute bacterial prostatitis is an infection of the prostate that is most commonly seen in older men. Approximately 8% of men will experience prostatitis-like symptoms, but the overall incidence of acute prostatitis is unknown.¹ Acute bacterial prostatitis can be diagnosed by way of a history and physical examination.¹ Symptoms commonly mirror those of a lower urinary tract infection (UTI), and patients may or may not present with fever. Evaluation also should include urinalysis and cultures, as well as prostatic fluid cultures if needed.

Antimicrobial therapy is the cornerstone of treatment for bacterial prostatitis. Pharmacotherapy should include agents with activity against traditional UTI-causing organisms. Special attention should be given to tissue penetration into the prostate and the duration of therapy.² Which antibiotics achieve adequate penetration, and how long should clinicians treat patients with acute bacterial prostatitis?

Patient Case

JH is a 67-year-old man with a history of hypertension and depression. His current medications include amlodipine, 10 mg once daily, and sertraline, 50 mg once daily. His blood pressure is well controlled, and all of his laboratory test results are within normal limits, including his levels of potassium and serum creatinine (estimated creatinine clearance, 75 mL/min). He presents with concern for dysuria, increased urinary frequency, and suprapubic pain over the past week.

Upon digital rectal examination, the patient’s prostate is tender and enlarged. A urinalysis is performed, the results of which reveal pyuria and the presence of nitrite-positive bacteria. Based on these findings, you make a diagnosis of acute bacterial prostatitis, and you would like to initiate antibiotic therapy. The patient has an allergy to ciprofloxacin (tendonitis). Which antibiotic should you use, and for how long should you treat this patient?

The Evidence

In patients with systemic symptoms requiring hospitalization, treatment with intravenous broad-spectrum cephalosporins or extended-spectrum penicillins is recommended, since these agents achieve significant concentrations within the prostate. However, for patients who are eligible for outpatient oral treatment, the decision is more complicated.

One of the biggest challenges of treating acute bacterial prostatitis with oral therapy is achieving adequate antibiotic penetration within the prostate tissue. Antibiotic penetration initially may be improved due to prostate inflammation during the acute infection; however, as the infection responds to therapy and the inflammation subsides, the antibiotic will have a more difficult time penetrating into the gland and achieving adequate drug levels.

Fluoroquinolones have become the mainstay of pharmacotherapy for acute bacterial prostatitis and have been approved by the Food and Drug Administration for this indication. These agents achieve high concentrations in both the seminal fluid and prostatic tissues, as well as in the urine. However, the use of these agents should be reserved for definitive treatment, since they are associated with a growing rate of resistance and significant adverse effects.³

Trimethoprim-sulfamethoxazole (TMP-SMX) is an efficacious second-line treatment option for patients who are unable to tolerate fluoroquinolones or who have resistance to the class. TMP-SMX achieves adequate concentrations in the prostate, exhibits high oral bioavailability, and is active against most UTI-causing organisms. Unfortunately, TMP-SMX does not cover Pseudomonas species and is becoming increasingly resistant to organisms in the Enterobacteriaceae family.

Although not ideal, tetracyclines serve as a last-line agent for the treatment of acute prostatitis. While these agents are traditionally not known for great oral bioavailability, they will achieve adequate concentrations in the prostate tissue. However, tetracyclines exhibit limited activity against common pathogens and should be used with caution.

There is a paucity of data regarding the optimal treatment duration for acute bacterial prostatitis. Current recommendations are to treat patients with acute bacterial prostatitis for a minimum of 2 weeks,^1,3 but some experts recommend that treatment be continued for 4 weeks² or 6 weeks⁴ to ensure complete eradication of the bacterial pathogen, given the known limitations associated with antibiotic penetration into the prostate. Patients who are more severely ill at presentation likely require a longer course of treatment than do patients with minimal symptoms.

One rationale for the extended duration of treatment relates directly to the previously discussed antibiotic penetration into the prostate: Because it is more difficult to achieve adequate tissue concentrations in this organ, a longer duration of therapy is needed in order to ensure complete eradication of the offending pathogen. Shorter treatment durations increase the risk of inadequate treatment and recurrent infection and are associated with increasing rates of antimicrobial resistance; indeed, if a shorter duration of treatment (2 weeks) fails to eradicate the infection, a longer course (an additional 4-6 weeks) may be required, leading to a total duration of therapy that would exceed the initially longer course of 4 weeks.

Given these concerns, we favor a treatment duration of at least 4 weeks to increase the chances of complete eradication of the bacterial pathogens, although we recognize the lack of evidence to definitely support this recommendation compared with a 2-week treatment duration. Nevertheless, others also recommend treating for at least 4 weeks or even longer for similar reasons.^2,4

With these considerations in mind, it is paramount at the time of diagnosis and treatment to effectively differentiate between prostatitis and UTI, given the shorter antibiotic treatment required for a UTI; if a bacterial prostate infection is incorrectly diagnosed as a UTI, then the chances for an adequate treatment duration, and therefore successful treatment, are severely reduced.

Clinical Application

Fluoroquinolones are the ideal agents for the treatment of acute bacterial prostatitis. They achieve high concentrations within the prostate tissue and prostatic fluid. Several studies have established the efficacy of this class, which has allowed them to become the cornerstone of therapy. In the event that a patient has an allergy to these agents or experiences biological resistance, TMP-SMX should be considered as the next best option. Tetracyclines provide clinicians with a last option if these agents cannot be used. However, providers should be aware of the antibiotic resistance patterns in their community before prescribing these agents. Patients should receive a minimum course of 4 weeks of antibiotics. Treatment may be extended if chronic bacterial prostatitis develops.

Outcome of the Case

Based on his symptoms and physical examination findings (most importantly, the enlarged and tender prostate), JH receives a diagnosis of acute bacterial prostatitis. Given his past intolerance to a fluoroquinolone agent, he is started on oral TMP-SMX, 160 mg/800 mg, 1 tablet twice daily for 4 weeks. He is advised to monitor for resolution of his symptoms and is counseled on the importance of adhering to his regimen for the duration of treatment, staying well hydrated, and alerting the office if he develops a rash or any signs or symptoms consistent with an adverse reaction to TMP-SMX. 

Eric A. Dietrich, PharmD, BCPS, is a graduate of the University of Florida College of Pharmacy and completed a 2-year fellowship in family medicine where he was in charge of an anticoagulation clinic. He works for the College of Pharmacy and the College of Medicine at the University of Florida in Gainesville.

Kyle Davis, PharmD, BCPS, is a graduate of the University of Florida College of Pharmacy in Gainesville and completed a 2-year residency in internal medicine at Indiana University in Indianapolis. He is an internal medicine specialist at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina.

References:

1. Coker TJ, Dierfeldt DM. Acute bacterial prostatitis: diagnosis and management. Am Fam Physician. 2016;93(2):114-120.
2. Schaeffer AJ, Nicolle LE. Urinary tract infections in older men. N Engl J Med. 2016;374(6):562-571.
3. Lipsky BA, Byren I, Hoey CT. Treatment of bacterial prostatitis. Clin Infect Dis. 2010;50(12):1641-1652.
4. Wagenlehner FME, Weidner W, Naber KG. Therapy for prostatitis, with emphasis on bacterial prostatitis. Expert Opin Pharmacother. 2007;8(11):1667-1674.