Urinary Tract Infections in Compromised Hosts

Candiduria in renal transplant recipients: incidence, clinical repercussion, and treatment indication

INTRODUCTION

The incidence of candiduria in renal transplant recipients is unknown. In clinical practice, the indications for antifungal therapy are not well established. Furthermore, there is the problem of the choice of the antifungal drug since some of them may select resistant Candida species, or interact with immunosuppressive agents or only be used intravenously.

AIM

We sought to study the incidence, clinical repercussions and effectiveness of antifungal treatment to prevent recurrence of candiduria.

MATERIALS AND METHODS

We examined all episodes of Candida-positive urine cultures (>50,000 cfu/mL) in 996 recipients over 2 years. We considered the Candida species, administered treatment, presence of fever, requirement for hospital admission versus outpatient case, occurrence of simultaneous bacterial urinary tract infection (UTI), antibiotic use during the week before candiduria, and presence of an indwelling urinary catheter.

RESULTS

Among 996 subjects, 34 displayed 83 episodes of candiduria, yielding an accumulated incidence of 3.4% after 2 years. The frequency was higher among women (6.3% vs 1.7%, P<.001). Of the 45 outpatient episodes (54.2%), 17 were treated and one required hospitalization (5.9%). Of the 28 nontreated outpatients, two were hospitalized (7.1%, P=.68 vs treated patients). All cases of hospital admission presented simultaneous bacterial UTI, none developed candidemia, and two patients did not receive any antifungal therapy. With respect to the first episodes of each patient (n=34), 5/11 treated (45.5%) and 4/23 untreated (17.4%) patients developed recurrences (P=.095). Selection of more resistant Candida species was not observed. Fifty cases (60%) were associated with antibiotic therapy and 34 (41%) the presence of a urinary catheter.

CONCLUSIONS

It does not seem necessary to treat candiduria in this setting. Antifungal therapy was not associated with either a reduction in recurrence or the appearance of more resistant species in this study. We observed no important clinical repercussions.

Management of urinary tract infections and lymphocele in renal transplant recipients

The most frequent infectious complication after renal transplantation is urinary tract infection. This article deals with antimicrobial prophylaxis, treatment of early and relapsing urinary tract infections, and management of asymptomatic bacteriuria in renal transplant patients. The incidence of lymphocele after renal transplantation varies, and its treatment is still controversial. Management options are discussed.

Bacteriuria and urinary infections in the elderly

Aging is associated with a decreased physiological functioning, reflecting the body's progressive inability to maintain homeostasis as age increases. The physiologic dysfunctions experienced in response to the aging process increase the individual's susceptibility to infection. Many elderly subjects are hospitalized for the care and treatment of functional disabilities; thus, an increased exposure to possible uropathogens (many with antimicrobial resistance) often results in infection. Additionally, indwelling catheters and other attending procedures may provide a microenvironment conducive to infection. In catheterized patients, the drainage bag often is infected with polymicrobes, which enhances the transference of antimicrobial genetic information. Postmenopause reflects a decrease in circulating estrogen, and a relational decrease in lactobacilli colonization with a lower vaginal pH. Consequently, vaginal colonization with possible uropathogenic and gastrointestinal bacteria increases, which partially may account for the generally higher incidence of bacteriuria in elderly women as opposed to elderly men. Urinary infections in the elderly more commonly are asymptomatic. Treatment for asymptomatic bacteriuria is not justified and will often present opportunities for the infecting organism to acquire antimicrobial resistance. Only symptomatic bacteriuria presenting adverse conditions in the host should be treated. Antimicrobial selection for the treatment of complicating symptomatic urinary infections in elderly subjects is complicated by the many physiological and environmental conditions associated with older age patients. Unfortunately, data confirming the efficacy and safety of antimicrobial agents for the treatment of symptomatic infections in the elderly presently are insufficient.

Diagnostics and categories of patients

Care in identifying and categorizing patients is a critical first step in proper drug evaluation. The appropriate diagnostic tests include culture and urinalysis. They are essential for the firm establishment of a diagnosis and should be sensitive and specific enough to meet the appropriate clinical requirements. The clinical categories outlined are encountered in clinical practice with a frequency that is sufficient to provide enough patients for an assessment of the response to antimicrobial therapy and to give information that will have practical value for clinicians.

Oral temafloxacin compared to norfloxacin for the treatment of complicated urinary tract infections

Temafloxacin is a new oral fluoroquinolone with broad-spectrum antimicrobial activity against gram-negative and gram-positive pathogens. The safety and efficacy of temafloxacin were evaluated in a multicenter, double-blind study of patients with complicated urinary tract infections. Patients were randomized to receive temafloxacin 400 mg (n = 138) or norfloxacin 400 mg (n = 141). Treatment was given orally twice daily for 10-14 days. Clinical response (cure or improvement) occurred in 75 of 78 patients (96%) in the temafloxacin group and in 89 of 91 patients (98%) in the norfloxacin group. Bacteriologic eradication rates in both treatment groups exceeded 95%. Adverse events occurred in a similar, low percentage of patients in both treatment groups and consisted primarily of nausea and dizziness. Temafloxacin appears to be as safe and effective as norfloxacin in the treatment of complicated urinary tract infections.

Ultrasonography in the differentiation of complicated and uncomplicated acute pyelonephritis

Differentiation of uncomplicated pyelonephritis versus complicated pyelonephritis has always been problematic. No clear physical signs or symptoms are diagnostic. To study differences between the two, we retrospectively reviewed charts of patients admitted to Charity Hospital, New Orleans, with febrile urinary tract infections. Criteria for inclusion were pyuria, positive urinary culture, and signs or symptoms of pyelonephritis. All patients underwent renal ultrasonography (US) before other diagnostic tests. US identified a potential emergency (hydronephrosis or abscess) in 11 of 98 patients (11.2%). The only significant contributing factor was the presence of diabetes mellitus, which was present in five of 11 emergent conditions and eight of 73 of the remainder (P = 0.003). US is inexpensive, easily obtainable in the emergency room, and sensitive enough to screen patients with pyelonephritis for complications. However, we believe it is mandatory in diabetics, because of the high incidence of abnormalities in this population.

The ecology and pathogenicity of urease-producing bacteria in the urinary tract

Urease activity is a physiological function of many bacteria that enables these organisms to utilize urea as a source of nitrogen. The association of ureolytic bacteria with human or animal hosts varies widely from a commensal relationship as demonstrated with skin microflora, a symbiotic relationship in the gastrointestinal tract, to a pathogenic relationship in the urinary tract. Since similar or identical species of bacteria such as Staphylococcus aureus are found in all three environments, the effect of urease activity on the host must be solely a function of the environment of these organisms. In this review, the importance of urease to bacteria is discussed, identifying the gastrointestinal tract as a major reservoir of ureolytic bacteria and investigating the urinary tract environment and the infectious struvite stone production that often accompanies urease-producing bacteria there. Finally, an infection model is presented which explains the development and growth of these urinary calculi and their remarkable persistence in spite of modern urological treatments.