Urinary Tract Infections in Older Adults: Current Issues and New Therapeutic Options

Sophie Robichaud, MD, FRCP(C); Joseph M. Blondeau, MSc, PhD, RSM(CCM), SM(AAM), SM(ASCP), FCCP

Disclosures

Geriatrics and Aging. 2008;11(10):582-588. 

In This Article

Management of Symptomatic Urinary Tract Infection among Older Adults

In the presence of clinical symptoms and signs suggestive of a UTI, it is recommended to obtain a pretherapy culture in order to tailor management to the current pathogens present in the urine and their pattern of antimicrobial susceptibility. The clinician should take into account the possible side effects of the antimicrobial chosen, drug interactions, any previous antimicrobials used in the particular patient, and the susceptibility pattern encountered in the patient's community or LTC facility. In the context of increasing resistance to trimethoprim/sulfamethoxazole, fluoroquinolones have been recommended as first-line therapy for UTI among older adults, especially in the community setting.[4,18] Ciprofloxacin and levofloxacin can be used; both compounds have a very good safety profile[18,30] ( Table 2 ).

If it is not possible to wait for results of a pretherapy culture because the patient is severely ill, a previous culture result can be used to aid in the choice of therapy; however, this should be reviewed in light of the new urine culture result when it becomes available. In this context, an agent with a broader spectrum of activity might be necessary.[3,7,25,27] This point is underlined by the review of Smith et al., showing that among patients who had been prescribed an antibiotic within the past month, 35% of isolates retrieved in cultures were sensitive and 65% were resistant to the antibiotic of recent use.[2]

Raz et al.[31] also reported a better outcome, defined as shorter time to defervescence and lower rate of reinfection, when patients with a chronic indwelling catheter had it changed when diagnosed with a symptomatic UTI. The duration of treatment recommended for women with a lower UTI is usually 7 days; it is extended to 14 days when signs of upper urinary tract involvement, such as flank tenderness or fever, are present. Men are usually treated for a longer period of time, 10-14 days.[18] Relapses, both asymptomatic and symptomatic, are common following treatment; 50% of men and women have a positive urine culture within 6 weeks after treatment. In this context, urine culture should not be done as a test of cure. It is to be noted that a symptomatic relapse in a man within 6 weeks of treatment demands a longer re-treatment of 6-12 weeks because of assumed prostatic involvement.[3,18]

Among the new available antimicrobials, some can be used for UTI treatment ( Table 3 ). It is to be noted that these drugs have also been approved for other indications (the clinician can refer to the product monograph or other reviews on the subject).

Fluoroquinolones are broad-spectrum agents available both in oral and parenteral preparations. Ciprofloxacin has been widely used for almost two decades now, both in community and hospital settings. It has been shown to be remarkably safe and has been used extensively in UTI treatment. A new extended-release formulation, Cipro XR (XL in Canada), has been approved for therapy in community-acquired acute cystitis and uncomplicated pyelonephritis. It is available in 500 mg and 1,000 mg daily dosages. As with the regular ciprofloxacin, 35% of the total oral dose is excreted in the urine.[32] The urinary drug concentration far exceeds the minimal inhibitory concentration required to inhibit the growth of 90% of strains (MIC90) ( Table 4 ) for common uropathogens over a 24-hour dosage administration interval.[33] This formulation has been evaluated in a multicentre, double-blind, randomized trial comparing it to immediate-release ciprofloxacin for complicated UTIs (e.g., presence of indwelling catheter, urinary retention, and neurogenic bladder). Both treatments were bacteriologically effective against various pathogens including E. coli. The extended-release formulation was slightly more effective in patients with a complicated UTI than the immediate-release ciprofloxacin (89.2% versus 81.4% eradication rate).[34] The safety and tolerability of this new formulation were similar in trials to those of the regular formulation of ciprofloxacin.

Ertapenem is a carbapenem, part of the larger beta-lactam group, and it has been approved for use in complicated UTI ( Table 3 ). Like the other carbapenems, it has a broad-spectrum of activity encompassing gram-positive and gram-negative bacteria and aerobic and anaerobic pathogens, with the exception of P. aeruginosa ( Table 4 ). It is available in both intramuscular and intravenous formulations with a 1 g daily dosage. Since ertapenem is mainly excreted in the urine, dosage adjustments are required in patients with renal insufficiency. Clinical and microbiological trials have shown success in 83.6-93.6% of ertapenem-treated patients, compared with 80.4-91.5% of those treated with other comparative agents.[30]

Since VRE and MRSA are a growing problem both in community- and hospital-based settings, linezolid, a new antimicrobial, is a valuable addition to the therapeutic armamentarium for these multiresistant bacteria. Linezolid has been approved for treatment of VRE infections ( Table 3 ). Part of a new class of antimicrobials named oxazolidinones, linezolid is active against gram-positive bacteria including Staphylococcus spp., Enterococcus spp., Streptococcus spp., VRE, and MRSA ( Table 4 ). Gram-negative bacteria are not part of its spectrum of activity. It is available in oral and parenteral formulations and has an excellent oral bioavailability (close to 100%). Clinical responses in the context of studies on skin and soft tissue infection, community-acquired pneumonia, and VRE infections ranged from 70 to 90%. The main side effects of this drug have been hematological changes including neutropenia and occasional neuropathies, usually when the course is continued for more than 14 days. Careful monitoring is thus required when the treatment is to be given for more than 14-21 days[30] ( Table 2 ).

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