Although fosfomycin (FM) has been approved by the FDA only for the treatment of uncomplicated urinary tract infection (UTI) in women, it may also have a role in the treatment of acute and chronic prostatitis among males given its favorable levels in the prostate tissue. 1-5
Despite lack of studies comparing the efficacy of FM with that of commonly used antibiotics for treatment of prostatitis, the potential utility of FM is supported by several reports of its efficacy in the treatment of prostatitis, including those caused by extended-spectrum beta-lactamase (ESBL)-producing gram-negative rods. 1,4-5
When considering FM for treatment of prostatitis, a higher dose than customary may be needed (3 g once daily, not every 48-72 h) . 4 Although the optimal duration of therapy with FM is unclear in this setting, 12-16 weeks of therapy was used in 2 patients with recurrent UTIs and prostatitis due to multi-drug resistant ESBL-positive E. coli. 4
Given its pharmacokinetics and lack of proven efficacy, avoid FM in pyelonephritis, perinephric abscess or UTI with bacteremia. 2
- Falagas ME, Vouloumanou EK, Samonis G, et al. Fosfomycin. Clin Microbiol Rev 2016;29:321-347. https://www.ncbi.nlm.nih.gov/pubmed/26960938
- Wankum M, Koutsari C, Gens K. Fosfomycin use. Pharmacy Times. November 30, 2017. https://www.pharmacytimes.com/publications/health-system-edition/2017/november2017/fosfomycin-use
- Cunha BA, Gran A, Raza M. Persistent extended-spectrum β-lactamase-positive Escherechia coli chronic prostatitis successfully treated with a combination of fosfomycin and doxycycline. International J Antimicrob Agents 2015;45:427-29. https://www.ncbi.nlm.nih.gov/pubmed/25662814
- Grayson ML, Macesic N, Trevillyan J, et al. Fosfomycin for treatment of prostatitis: new tricks for old dogs. Clin Infect Dis 2015;61:1141-3. https://www.ncbi.nlm.nih.gov/pubmed/26063723
- Falagas ME, Rafailidis PI. Fosfomycin: the current status of the drug. Clin Infect Dis 2015;61:1144-6. https://www.ncbi.nlm.nih.gov/pubmed/26063717
Although a common practice, follow-up blood cultures (FUBCs) may not be necessary in otherwise clinically stable or improving patients with aerobic gram-negative bacteremia. This is probably due to the often-transient nature of gram-negative bloodstream infections and less propensity of these organisms to cause intravascular infections (eg, endocarditis) compared to gram-positives. 1
A 2017 study addressing the value of FUBCs in gram-negative bacteremia found that repeat positive blood cultures were uncommon with positive results not associated with mortality or higher ICU admissions. 1 Specifically, 17 FUBCs had to be drawn to yield 1 positive result. Although the numbers of positive FUBCs were too low for in-depth analysis, it was concluded that FUBCs added little value in the management of gram-negative bacteremias.
In contrast, FUBCs are recommended in the following situations: 1-3
- Staphylocccus aureus bacteremia given the propensity of this organism to cause intravascular (eg, endocarditis) and metastatic infections.
- Presumed or documented endocarditis or intravascular device infections (eg, intravenous catheters and pacemakers) to document timely clearance of bacteremia
- Infections involving organisms that may be difficult to clear such as fungemia or multi-drug resistant pathogens.
As with many things in medicine, clinical context is important before ordering tests and blood cultures are no different. The urge to order FUBCs should also be balanced with the possibility of having to deal with contaminants.
- Canzoneri CN, Akhavan BJ, Tosur Z et al. Follow-up blood cultures in gram-negative bacteremia: Are they needed? Clin Infect Dis 2017;65:1776-9. https://www.ncbi.nlm.nih.gov/pubmed/29020307
- Tabriz MS, Riederer K, Baran J, et al. Repeating blood cultures during hospital stay: Practice pattern at a teaching hospital and a proposal for guidelines. Clin Microbiol Infect 2004;10:624-27. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1469-0691.2004.00893.x
- Mylotte JM, Tayara A. Blood cultures: Clinical aspects and controversies. Eur J Clin Microbiol Infect Dis 200;19:157-63. https://www.ncbi.nlm.nih.gov/pubmed/10795587
Suprapubic tenderness, costovertebral angle tenderness (CVAT) and fever seem to be more helpful in ruling in than ruling out infection. And, before you hang your hat on the available data, remember that most of the studies involve women with uncomplicated UTI in primary care or emergency department settings, not our older hospitalized patients at risk of complicated infections. With these caveats in mind….
Suprapubic tenderness has been reported in only about 15-20% of women with acute cystitis. 1
CVAT has been associated with symptomatic UTI but with only a weakly positive LR (1.7, 1.1-2.5), and an insignificant negative LR. 2 In a single center study involving hospitalized patients (mean age 53 y), CVAT was either absent or “obscure” in about 10% of patients with acute pyelonephritis on CT.3
Fever was associated with a positive likelihood ratio (1.6, 1.0-2.6) by 1 systematic study 2 but not another, 4 with insignificant negative LR in both. Fever was also absent in about 10% of hospitalized patients with pyelonephritis in the single center study above.3
So, when evaluating a patient with possible symptomatic UTI (particularly cystitis), the presence of physical exam findings may be more helpful than their absence.
If you like this post, sign up under MENU and get future pearls straight into your mailbox!
- Kurowski K. The woman with dysuria. Am Fam Physician 1998, 57:2155-2164. https://www.aafp.org/afp/1998/0501/p2155.html
- Bent S, Nallamothu BK, Simel DL, et al. Does this woman have an acute uncomplicated urinary tract infection? JAMA 2002;287:2701-2710. https://www.ncbi.nlm.nih.gov/pubmed/12020306
- Lee Y-J, Cho S, Kim SR. Unilateral and bilateral acute pyelonephritis: differences in clinical presentation, progress and outcome. Postgrad Med 2014;90:80-85. https://www.ncbi.nlm.nih.gov/pubmed/24255118
- Median-Bombardo D, Jover-Palmer A. Does clinical examination aid in the diagnosis of urinary tract infections in women? A systematic review and meta-analysis. BMC Family Practice 2011;12:111. https://bmcfampract.biomedcentral.com/articles/10.1186/1471-2296-12-111