Gail Itokazu, Pharm.D.
Spring 1998

Urinary Tract Infections

1. Goals
2. Etiology
3. Diagnosis
4. Management
5. Management Options for the Catheterized Patient
6. Prostatitis
7. Case 1

Required Reading

1. Mullenix TA et al. Urinary Tract Infections and Prostatitis. In Pharmacotherapy: A Pathophysiologic Approach. DiPiro JT, et al, eds. Elsevier, NY, 3rd Edition, 1997. Chapter 109, pp 2173-2193.

Optional Reading

The following reading is not required, but may enhance your understanding of the material in this section.

1. Warren JW. Catheter-associated urinary tract infections. Infect Dis Clin NA 1997; 11:609-622.

GOALS:

1. Understand the pathogenesis of urinary tract infections.
2. Be able to recommend appropriate antimicrobial therapy for patients with urinary tract infections.
3. Understand the goals of therapy for patients with urinary tract infections.

INTRODUCTION

1. List the clinical syndromes associated with infections of the urinary tract.
2. Discuss the criteria for defining significant bacteruira.

EPIDEMIOLOGY

Be aware that the prevalence of urinary tract infections varies with age and gender.

PATHOGENESIS

Failure of host defense mechanisms is the cause of the majority of UTIs.

Route of Infection

1. Discuss the possible routes via which UTIs can be acquired.
2. Compared to males, discuss why colonization of the female urethra with organisms causing urinary tract infections is more common.
3. List 3 factors that can influence the development of UTIs once potentially pathogenic organisms have reached the urinary tract.

Host Defense Mechanisms

1. Be aware of the various host defense mechanisms of the urinary tract which aid in the prevention of UTIs, e.g., factors which prevent bacterial invasion or eliminate bacteria that reach the bladder.

Bacterial Virulence Factors

1. Define virulence as it relates to infectious diseases.

Predisposing Factors to Infection

1. Be able to discuss how underlying structural abnormalities such as obstruction and vesicoureteral reflux predispose patients to UTIs.
2. Be aware of other risk factors for UTIs such as urinary catheterization and pregnancy.

ETIOLOGY

1. Discuss the most common bacteria associated with uncomplicated community-acquired UTIs.
2. Discuss the differences in the microbiologic causes of uncomplicated community-acquired UTIs vs complicated nosocomial UTIs.

Based on the differences in bacterial etiologies in uncomplicated community-acquired and nosocomial complicated UTIs, develop antimicrobial regimens you would suggest for the treatment of UTIs in these situations (see table 109.2 and 109.3 for a list of various options).

CLINICAL PRESENTATION

1. Compare and contrast the typical symptoms associated with upper tract and lower tract infections.
2. As elderly patients may not always present with typical symptoms associated with UTIs, what signs and symptoms could be clues that they are experiencing a UTI?

DIAGNOSIS

1. Discuss the key to the diagnosis of a UTI.
2. List the 3 acceptable methods of urine collection used to make the diagnosis of a UTI.
3. Discuss the situations when you would use the methods of urine collection you listed in item #2 above.
4. Be aware that routinely used diagnostic tests for UTIs, e.g., microscopic examination of the urine for leukocytes and nitrate reduction tests may give false-negative results in some patients with a UTI.
5. Discuss the most reliable method of diagnosing a UTI.
6. Be aware of the patient population with symptomatic infection who may have less than 10⁵ bacterial/ml.

MANAGEMENT

Management of patients with UTIs includes: 1) evaluation to assess the presence and likely location of an infection, 2) selection of an antimicrobial agent, 3) determining the duration of therapy, and 4) a follow-up evaluation.

1. Discuss some of the factors to consider before selecting an antimicrobial regimen.

In order to eradicate organisms causing an infection, it is important for the drug to reach adequate concentrations at the site of infection. In the case of lower tract infections, blood antimicrobial levels may not be important, whereas if there is a bacteremia associated with a urinary tract infection, blood levels are important.

Be aware that not all antimicrobials indicated for lower urinary tract infections can be used for patients with concurrent bacteremias because of their poor oral bioavailability, e.g., norfloxacin.

Uncomplicated Urinary Tract Infections in Females

1. Be aware of the most common form of UTI in this population and the most common organism against which therapy should be directed.
2. Discuss the therapies you would consider initiating in this patient population (review table 109.4 for various options).
3. Discuss the advantages/disadvantages of single dose, short-course (3 day), and full course (7 day) therapies for UTIs in this population.
4. Discuss the situations in which short-course (3 day) therapy is generally recommended.
5. Discuss the follow-up evaluation to assess the effectiveness of therapy in this patient population.

Symptomatic Abacteriuria

1. Define symptomatic abacteriruia (acute urethral syndrome).
2. Based on the organisms isolated in females with symptomatic abacteriuria, develop a treatment plan (include antimicrobial selection, duration of therapy, and follow-up plan).

Asymptomatic Bacteriuria

1. Define asymptomatic bacteriuria and the likely patient populations to have this type of UTI.
2. Discuss why treatment of children with asymptomatic bacteriuria is recommended.

Complicated Urinary Tract Infections

Acute Pyelonephritis

1. Discuss the clinical presentation of patients with pyelonephritis.
2. Discuss the lab tests you would obtain in these patients.
3. Based on the most likely pathogen(s) found in patients with acute pyelonephritis, discuss the empiric antimicrobial regimens you would begin. Include a discussion on the duration of therapy, and follow-up evaluations you would recommend (review table 109.4).

Urinary Tract Infections in Males

1. In contrast to females, discuss why UTIs in males are considered complicated.
2. List the common causes of UTIs in males.

Recurrent Infections

1. Define reinfection.
2. Management of patients with reinfection depends in part on predisposing factors to infection, number of episodes per year, and patient preference. Be aware that patient populations prone to reinfection include women following sexual intercourse, diaphragm use for birth control and post-menopausal women.
3. Define relapse.
4. Discuss the reasons for relapsing infection.

Special Conditions

Urinary Tract Infection in Pregnancy

1. Discuss why pregnant women with asymptomatic bacteriuria should receive a 7 day course of appropriate antimicrobial therapy.

Catheterized Patients (if interested, see optional reading, Warren JW. Catheter-associated urinary tract infections. Infect Dis Clin NA 1997; 11:609-622).

Comments: Bacteriuria is a common finding in catheterized patients. Risk factors for bacteriuria include duration of catheterization, microbial colonization of drainage bag, diabetes mellitus, absence of antibiotic use, and periurethral colonization with organisms associated with bacteriuria. The duration of urinary catheterization is a convenient way to classify patients, i.e., short-term vs long-term catheterization. A comparison of clinical setting, risk factors for bacteriuria, and complications in these groups of patients is summarized below.

Catheterized Patients

Management Options for the Catheterized Patient

Prevent Bacteriuria

1. Use of closed drainage systems
2. Remove catheter as soon as possible

Role of Antimicrobials:

Decreases the incidence of bacteriuria during the first few days, followed by the emergence of resistant organisms, thus many experts do not recommend prophylactic antimicrobials

Possible cases in which prophylactic antibiotics may be beneficial:

Patients at high risk for complications associated with bacteriuria such as renal transplant patients and neutropenic patients.

Preventing Complications of Bacteriuria

Aysmptomatic Bacteriuria

In general, no antibiotics recommended, but some possible exceptions are:

1. bacteriuria caused by organisms with a high likelihood of causing bacteremia; this has been demonstrated for S. marcescens.
2. To control a cluster of infections.
3. Patients at high risk for complications such as granulocytopenic patients, solid organ transplant patients, pregnant women.
4. Patients undergoing urologic surgery.

Symptomatic Bacteriuria

Treat with antimicrobials.

PROSTATITIS

1. Discuss the differences between acute bacterial prostatitis, chronic prostatitis, and prostatodynia.

Pathogenesis /Etiology

1. Discuss the possible routes of bacterial infection of the prostate.

2. List the most frequent organisms in bacterial prostatitis.

Clinical Presentation/Diagnosis

1. List the common symptoms of acute bacterial prostatitis.

2. List the common symptoms of chronic bacterial prostatitis.

Treatment

1. Discuss antimicrobial treatment options for acute and chronic bacterial prostatitis.

2. Discuss the advantages/disadvantages of the various treatment options. You should consider efficacy, toxicity, and cost in your discussion.

3. Discuss the treatment duration for acute and chronic bacterial prostatitis.

Case 1.

CC: frequent urination, pain on urination, back pain, fever, shaking chills, headache, nausea, vomiting, malaise

HPI: BB is a 30 year old female who presented with the above complaints which began over the past 3-4 days. Because she is 20 weeks pregnant, the only medication she took was acetaminophen which provided temporary relief of her pain and fever.

PMH: None. No known drug allergies.

PE: temp 103, HR 100, RR 18, B/P within normal limits

ABD: abdominal tenderness, right flank pain, costovertebral tenderness

LABS: urinalysis >100 WBCs, culture and sensitivity are pending, blood cultures pending.

WBC w/ differential – 18.5 mm³ with a left shift

1. What is your assessment (i.e., problem list and possible cause(s) for each problem). Providing subjective and objective data to support each problem is helpful when preparing your assessment of the patient.

This is a previously healthy female who is 20 weeks pregnant who presents with subjective findings related to the urinary tract (e.g., dysuria, frequency). Her physical exam is also consistent with an upper urinary tract infection (e.g., flank pain and costovertebral tenderness). An objective lab test that points to a urinary infection is the abnormal urinalysis.

Her fever should prompt a search for an infectious etiology of her UTI. Findings suggestive of a systemic infection with bacteremia include fever, rigors, shaking chills.

Finally, her risk factor for a UTI is her pregnancy.

Based on the above, the patient is likely to have an upper tract infection, e.g., pyelonephritis.

2. Select an antimicrobial regimen for this patient with a presumptive bacteremia and pyelonephritis. Consider the likely bacterial pathogens.

E. coli is the most likely pathogen in this patient. Since she has not received prior antimicrobials, it is unlikely that she would have an infection caused by more resistant organisms. Some treatment options are noted in Table 109.4 of DiPiro’s; you should take note of antimicrobials which should not be used in pregnancy, e.g., quinolones and aminoglycosides; and

trimethoprim/sulfamethoxazole during certain trimesters.

3. How long would you treat this patient?

2 weeks for pyelonephritis.

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