Genitourinary infection

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Background

Definitions

  • UTI = significant bacteriuria in presence of symptoms
    • Described by location: urethritis, cystitis, or pyelonephritis
  • Relapse
    • Recurrence of symptoms w/in month despite tx
      • Caused by same organism and represents treatment failure
  • Reinfection
    • Development of symptoms 1-6mo after tx
    • Usually due to a different organism
    • If pt has >3 recurrences in 1 yr consider tumor, calculi, DM
  • Men <50 yr: symptoms of dysuria or urinary frequency usually due to STI
  • Men >50 yr: incidence of UTI rises dramatically d/t prostatic obstruction
  • Uncomplicated UTI:
    • No structural or functional abnormalities w/in urinary tract or kidney
    • No relevant comorbidities that place pt at risk for more serious adverse outcome
    • Not associated with GU tract instrumentation

Risk factors for complicated UTI

  1. Male sex
    1. In young males dysuria is more commonly d/t STI
    2. Suspect underlying anatomic abnormality in men with culture-proven UTI
  2. Anatomic abnormality of urinary tract or external drainage system
    1. Indwelling urinary catheter, stent
    2. Nephrolithiasis, neurogenic bladder, polycystic renal disease, recent instrumentation
  3. Recurrent UTI (three or more per year)
  4. Advanced age in men (BPH, recent instrumentation, recent prostatic biopsy)
  5. Nursing home residency (w/ or w/o indwelling bladder catheter)
  6. Neonatal state
  7. Comorbidities (DM, sickle cell disease)
  8. Pregnancy
  9. Immunosuppression (AIDS, immunosuppressive drugs)
  10. Advanced neurologic disease (CVA w/ disability, spinal cord injuries)
  11. Known or suspected atypical pathogens (Non–E. coli infection)
  12. Known or suspected abx resistance (resistance to cipro predicts multidrug resistance)

Bacteriology

  • Most common pathogen is E. coli
  • Anaerobic organisms are rarely pathogenic (do not grow well in urine)
  • Complicated UTIs more likely to be caused by pseudomonas or enterococcus


Diagnosis

Clinical Features

  • UTI dx requires both bacteriuria and clinical symptoms
    • Cystitis = Dysuria, hematuria, frequency, urgency, suprapubic pain, CVAT
    • Pyelo = Cystitis sx AND fever/chills/nausea/vomiting
      • CVAT alone may be referred pain from cystitis
      • CVAT is only physical examination finding that increases likelihood of a UTI
  • Urethritis
    • In males more likely due to chlam/GC
    • In females more likely due to chlam/GC if e/o cervicitis or "sterile pyuria"
  • Complicated UTI
    • Pts may not have classic symptoms; may only have weakness, fever, abd pain, AMS

Labs

UA

WBC count
  • WBC >5 in pt w/ appropriate symptoms is diagnostic
    • Lower degrees of pyuria may still be clinically significant in presence of UTI sx
      • False negative may be due to: dilute urine, systemic leukopenia, obstruction
    • WBC 1-2 w/ bacteriuria can be significant in men
      • More likely represents urethritis or prostatitis from STI
Nitrite
  • Very high specificity (>90%) in confirming diagnosis of UTI
  • Low sensitivity (enterococcus, pseudomonas, acinetobacter are not detected)

Urine Culture

  • Indicated for:
    • Complicated UTI
    • Pregnant women
    • Children
    • Adult males
    • Relapse/reinfection

Blood Culture

  • Not indicated
    • Organisms in blood cx matched those in urine cx 97% of time

Imaging

  • Consider if pyelonephritis and any of the following:
  1. History of renal stone
  2. Poor response to abx
  3. Male
  4. Elderly
  5. Diabetic
  6. Severely ill



Treatment The discussion of treatment is divided into two sections, Acute Cystitis and Acute Pyelonephritis and Complicated Urinary Tract Infection, with the understanding that although pyelonephritis can be classified as uncomplicated if the patient has normal anatomy and is otherwise healthy, complicated UTI is managed much the same as pyelonephritis, with larger drug dosages and/or broader-spectrum antibiotics, urine culture to guide ongoing therapy, and longer duration of treatment

ACUTE CYSTITIS AND UNCOMPLICATED URINARY TRACT INFECTION

SEE TABLE 94-5 Table 94-5 contains treatment recommendations for four separate groups of patients with UTI: (1) women with uncomplicated lower tract disease, (2) women with complicated UTI or pyelonephritis, (3) men with upper or lower UTI, and (4) women with UTI symptoms in whom coexistent urethritis cannot be excluded

Specific antibiotic choice varies according to local resistance patterns.24–27 Local guidelines for antimicrobial use should be consulted. Rates of resistance to trimethoprim-sulfamethoxazole (TMP-SMX) are over 30% in some areas, whereas resistance to ciprofloxacin approaches 11%.26,27 Resistance to ciprofloxacin predicts multidrug resistance

Most uncomplicated UTIs in women can be treated with a 3-day course of antibiotics. UTIs not thought to be sexually transmitted in young males should be treated with a 7- to 10-day course of antibiotics. Fourteen-day courses are indicated for more complex cases involving patients with significant comorbidities, diabetic patients, those who are immunocompromised, and the elderly

Currently, recommendations are to avoid TMP-SMX as the first-line empiric agent of choice when local resistance rate exceeds 20%, unless treating based on the results of urine culture with sensitivity testing.

Nitrofurantoin extended release is also an effective agent for treating UTI, although it is not effective against S. saprophyticus. The twice-a-day formulation is more expensive than ciprofloxacin. Nitrofurantoin is a favorite antibiotic among obstetricians for treatment of asymptomatic bacteriuria and otherwise uncomplicated UTI in pregnant women. A 5-day course of nitrofurantoin extended release is as effective as 3 days of TMP-SMX therapy.22 Nitrofurantoin has a favorable resistance profile in many regions, is a generally safe alternative, and concentrates well in the urine. Choosing to use nitrofurantoin avoids contributing to another problem—growing pathogen resistance to fluoroquinolones due to their frequent use to treat a wide array of infections.

Because of bacterial resistance to traditional antibiotics used for UTI, local sensitivities may be used to guide the substitution of alternative agents such as cephalosporins. Third-generation cephalosporins are highly effective against enterobacteria. First-generation cephalosporins are more effective against staphylococci. Amoxicillin-clavulanate is less effective than fluoroquinolones30 or oral cephalosporins31 for UTI due to enterobacteria. It also often leads to selection of Klebsiella. Aminopenicillins are therefore not recommended as first-line therapy in uncomplicated UTI. Another important alternative is the phosphonic acid antibiotic fosfomycin. A single 3-gram dose is highly effective, the resistance rate is only 2%,32 and the drug is the first-line choice for uncomplicated UTI as recommended by the European Association of Urology.23

In cases of treatment failure, or in the host with a structural or immunologic defect, one of the fluoroquinolones should be considered. Urine culture with sensitivity testing should be performed to guide treatment. Where TMP-SMX resistance is known to be higher than 10% to 20% and empiric short-course (3-day) therapy is indicated, fluoroquinolones may be the best choice. Unfortunately, fluoroquinolone resistance in organisms causing UTI is already becoming a problem and is expected to increase dramatically in the coming years. Fluoroquinolones are also the favored agents for treating UTI in men in most cases. UTI in men should not be treated with a 3-day course of antibiotics.

If the patient has UTI symptoms and there is also suspicion of Chlamydia infection and gonorrhea (cervicitis and/or salpingitis) antibiotic treatment is more complex. If the patient is not sufficiently ill to require admission and is not pregnant, one initial treatment approach is to use ofloxacin, 400 milligrams twice a day for 14 days. Ofloxacin effectively covers all common UTI pathogens as well as Chlamydia and Neisseria gonorrhoeae, but increasing N. gonorrhoeae resistance to fluoroquinolones has been reported. If salpingitis is clinically evident, additional therapy is required (see Chapter 144, Sexually Transmitted Diseases). When treating a young teenage patient with recurrent UTI, if the patient is sexually active, the physician should consider counseling the patient regarding contraception and prevention of STDs.

Recurrent infection is often due to a new serotype of E. coli, or it may be due to organisms that have newly developed resistance as a result of exposure to antibiotics excreted into the GI tract. If empiric therapy is considered for recurrent infections, it should probably be with fluoroquinolones unless community resistance to TMP-SMX is known to be low. However, successful management in cases of recurrent UTI depends on urine culture and sensitivity testing. Because many factors are involved in reinfection and some of these are correctable, referral to a primary care physician is needed.

In uncomplicated UTIs, the urine should be bacteria free in 24 to 48 hours with substantial relief of symptoms within the same time period. Three-day regimens are the standard of care for uncomplicated infections in nonpregnant women

Nevertheless, in 20% to 30% of patients given short-duration therapy, treatment fails or there is rapid relapse. A longer treatment course (Table 94-6) is indicated for patients with complicated UTIs, including those with symptoms lasting longer than a week, patients with diabetes, individuals who had a UTI in the previous 4 weeks, men, those who are >65 years of age, and women who use spermicides or a diaphragm.1,3,5,7–10,13 Those patients who experience relapse need 14 days of subsequent therapy

-Empiric Initial Treatment for Inpatient Management of Pyelonephritis and Complicated Urinary Tract Infection- - Ciprofloxacin, 400 milligrams IV every 12 h Ceftriaxone, 1 gram IV once daily Cefotaxime, 1 or 2 grams IV every 8 h Gentamicin, or tobramycin, 3.0 milligrams/kg/d divided every 8 h ± ampicillin 1–2 grams every 4 h Trimethoprim-sulfamethoxazole, 160/800 milligrams IV twice a day Piperacillin-tazobactam, 3.375 grams IV every 6 h Cefepime, 2 grams IV every 8 h Imipenem, 500 milligrams IV every 8 h Meropenem, 1 gram IV every 8 h

ACUTE PYELONEPHRITIS AND COMPLICATED URINARY TRACT INFECTION See 94-5 for outpt, see table 94-6 for inpt

Duration of Therapy for Pyelonephritis and Complicated Urinary Tract Infection Although treatment courses as short as 5 days have been studied in patients with pyelonephritis,36 guidelines recommend a total of 14 days of therapy for the majority, regardless of whether or not parenteral therapy is used.9 For patients with sepsis syndrome, a total of 21 days of treatment may be required to eradicate bacteriuria

Disposition and Follow-Up DISPOSITION FOR PATIENTS WITH UNCOMPLICATED URINARY TRACT INFECTION OR CYSTITIS Patients who are unable to retain fluids and medication should be admitted and antibiotics chosen as listed in Table 94-6. Adjunctive therapies for patients in stable enough condition for discharge include ingestion of plenty of fluids to enhance diuresis and fruit juices containing vitamin C to acidify the urine, consumption of a proper diet, and frequent voiding (at least every 2 hours) to diminish tissue contact with bacteria. The offer of 1 to 2 days of treatment with an oral bladder analgesic, such as phenazopyridine, is considerate when urination is painful for the patient. Cranberry juice appears to be mildly effective in reducing the incidence of recurrent infection.37 There is no conclusive evidence that postcoital voiding prevents cystitis.38

DISPOSITION FOR PATIENTS WITH PYELONEPHRITIS Young, otherwise healthy females with uncomplicated acute pyelonephritis are candidates for outpatient management provided they are able to tolerate fluids and medication.28,29 Urine culture with sensitivity testing should be performed. Patients should be instructed to return if they experience increasing pain, fever, or vomiting. Prescriptions for systemic analgesics (e.g., hydrocodone plus acetaminophen) and antiemetics (i.e., promethazine) should be considered. Overall, 80% to 90% of selected patients with acute pyelonephritis respond well to outpatient oral therapy.

The decision to admit a patient with UTI is based on age, host factors, and response to initial ED interventions. Overall, approximately 1% to 3% of patients with acute pyelonephritis die from the infection, with younger patients experiencing the fewest complications. Factors associated with an unfavorable prognosis are advanced age and general debility, renal calculi or obstruction, a history of recent hospitalization or instrumentation, diabetes mellitus, evidence of chronic nephropathy, sickle cell anemia, underlying carcinoma, and immunocompromised state [e.g., chemotherapy, human immunodeficiency virus infection/acquired immunodeficiency syndrome (HIV/AIDS)].

Dangerous complications of acute pyelonephritis include acute papillary necrosis with possible ureter obstruction, septic shock, perinephric abscesses, and emphysematous pyelonephritis (see Imaging above).


PATIENTS WITH HUMAN IMMUNODEFICIENCY VIRUS INFECTION/ACQUIRED IMMUNODEFICIENCY SYNDROME In HIV/AIDS patients, resistance to TMP-SMX is increased due largely to its use in Pneumocystis jiroveci prophylaxis. Fluoroquinolones should be the initial antibiotic used for UTI in these patients unless urine culture and sensitivity test results are available to guide therapy. Most UTIs in HIV/AIDS patients are caused by typical pathogens or common STD organisms. Mycobacterium tuberculosis is an infrequent cause of UTI in the HIV/AIDS population. Close outpatient follow-up (recheck in 1 week) and possible infectious disease consultation is warranted when treating UTI in this population

Special Populations PREGNANT WOMEN See Chapter 102, Comorbid Diseases in Pregnancy, for a detailed discussion.


Complications

  • Suspect in pts who have inadequate or atypical response to tx for presumed pyelo
  1. Acute bacterial nephritis
    1. CT shows ill-defined focal areas of decreased density
  2. Renal/Perinephric abscesses
    1. Sign/symptoms similar to pyelo (fever, CVAT, dysuria)
    2. Occurs in setting of ascending infection w/ obstructed pyelo
    3. Associated w/ DM and renal stones
    4. Also occurs due to bacteremia w/ hematogenous seeding (Staph)
  3. Emphysematous pyelonephritis
    1. Rare gas-forming infection nearly always occurring in pts w/ DM and obstruction
      1. Pts appear toxic and septic; nephrectomy may be required


See Also

Source

Tintinalli