Urinary Tract Infection

1. Urinary Tract Infection

2. Table of contents
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04
02
05
03
06
Introduction Terminology Microbiology
Diagnostic approach Management
Clinical manifestation

3. Introduction
01

4. Introduction
Urinary tract infections (UTI) include cystitis (infection of the bladder/lower
urinary tract) and pyelonephritis (infection of the kidney/upper urinary tract).
The pathogeneis of UTI begins with colonization of the vaginal introitus or
urethral meatus by uropathogens from the fecal flora, followed by ascension
via the urethra into the bladder. Pyelonephritis develops when pathogens
ascend to the kidneys via the ureters. Pyelonephritis can also be caused by
seeding of the kidneys from bacteremia.

5. Male

6. Female

9. Terminology
02

10. Terminology - We use the term acute complicated urinary tract infection
(UTI) to refer to an acute UTI with any features that suggest that the
infection extends beyond the bladder. These include fever (e.g.,
>99.9°F/37.7°C), other signs or symptoms of systemic illness (including
chills, rigors, or altered mental status), flank pain, and costovertebral angle
tenderness. By this definition, pyelonephritis is a complicated UTI,
regardless of patient characteristics. This definition is distinct from
traditional categorizations of UTI and is more focused on the clinical
presentation and severity of illness.

12. Defination by classificaton

13. Microbiology
03

14. Relevant uropathogens include primarily Escherichia coli, but also other
Enterobacterales, other gram-negative bacilli (including Pseudomonas
aeruginosa), staphylococci, enterococci, and Candida species. Risk factors
for resistant organisms include recent broad-spectrum antimicrobial use,
health care exposures, and travel to parts of the world where multidrug-
resistant organisms are prevalent .
Microbiology
SEEK PP = S - S. saprophyticus, E - E. coli, E - Enterococcus, K - Klebsiella, P - Proteus, P -
Pseudomonas are the bacteria commonly associated with UTIs.

15. Pathophysiology

17. 04
Clinical
manifestations

18. Clinical suspicion - Acute complicated UTI should be suspected in
patients with dysuria, urinary frequency or urgency, or suprapubic pain
who also have fever, chills, flank pain, or otherwise appear clinically ill.
Acute pyelonephritis, specifically, should be suspected in patients
presenting with fever and flank pain, even in the absence of typical
symptoms of cystitis. In men, pelvic or perineal pain accompanying
urinary symptoms suggests prostatitis. UTI is also often suspected in
patients with pyuria and bacteriuria who have nonspecific signs of
systemic illness, such as lethargy or delirium, or in patients with
nonlocalizing fever or sepsis.
In patients with fever and/or flank pain, which are usually absent in lower UTIs, consider a
more serious infection (e.g., pyelonephritis).
Dysuria without urgency or frequency may suggest vaginitis or sexually
transmitted urethritis rather than cystitis, especially if accompanied by abnormal vaginal or
urethral discharge.

19. Key diagnostic factors

20. Other diagnostic factors

21. Diagnostic
approach
05

22. Evaluation - For patients with suspected acute complicated UTI, we send
urine for both urinalysis (either by microscopy or by dipstick) and culture
with susceptibility testing. Imaging is generally reserved for those who are
severely ill, have suspected urinary tract obstruction, have persistent
symptoms despite 48 to 72 hours of appropriate antimicrobial therapy, or
have recurrent symptoms.
UTI is primarily a clinical diagnosis that is supported by typical findings on urinalysis. Urine
culture is indicated in select cases to determine the causative pathogen and
adapt antibiotic treatment.
Investigate isolated urethritis (i.e., without concomitant cystitis) for causes other than lower
UTI (e.g., STI, reactive arthritis).

23. Catheter-associated UTI is
defined as the presence of
symptoms or signs compatible
with a UTI in people with a
catheter with no other other
identified source of infection,
plus significant levels of bacteria
in a catheter or a midstream
urine specimen when the
catheter has been removed
within the previous 48 hours.

25. Urinalysis test strip Pyuria and bacteriuria on microscope
Practical tip
A urine dipstick test looks for positive leukocytes or nitrites to indicate a UTI.
Organisms such as Escherichia
coli or Klebsiella, Enterobacter, Proteus, Staphylococcus,
or Pseudomonas species reduce nitrate to nitrite in the urine, therefore the
presence of nitrite on a urinalysis is an indicator of a UTI.

26. Diagnosis - The diagnosis of acute complicated UTI is made in patients
who have consistent clinical findings as well as pyuria and bacteriuria. UTI
is unlikely if pyuria is absent.
In patients with complicated or recurrent urinary tract infections, a urine culture should be
obtained prior to initiating antibiotic treatment. False negative results are possible if a culture is
obtained after the patient has received antibiotics.
In patients with lower abdominal pain and sterile pyuria, consider bladder or ureteral irritation
from an intraabdominal or pelvic infection unrelated to the urinary
tract (e.g., appendicitis, diverticulitis).
Imaging is not routinely necessary for patients with uncomplicated lower UTI.

32. Ultrasonography of normal kidney Ultrasonography of acute pyelonephritis

33. CT scan of acute pyelonephritis
Normal CT

34. Computed tomography scan of bilateral acute pyelonephritis

35. CT of Xanthogranulomatous Pyelonephritis

37. Management
06

38. Indications for hospitalization - Indications for inpatient
management include sepsis or critical illness, persistently high fever
(e.g., >38.4°C/>101°F) or pain, marked debility, suspected urinary
tract obstruction (e.g., due to nephrolithiasis), concern about
medication adherence, and inability to maintain oral hydration or take
oral medications.
Outpatient management is appropriate for others, including those who
can be stabilized with initial treatment (e.g., rehydration and
antimicrobials) in an outpatient facility or the emergency department.

40. Primary Regimens
•Empiric therapy:
• Ciprofloxacin (500 mg po bid or extended release 1000 mg po q24h or 400 mg IV
q12h)
• Levofloxacin 750 mg po/IV q24h
• If patient with systemic illness or high risk for multi-drug resistant organisms,
consider alternative regimens below for empiric therapy
•Specific therapy: based on bacterial speciation and drug susceptibility testing
Alternative Regimens
•Nitrofurantoin (Macrobid) 100 mg po bid (if without signs or symptoms of systemic
infection - fever, flank pain)
•TMP-SMX-DS 1 tab bid (If local prevalence of resistance to TMP/SMX is < 20%)
•If high risk for multi-drug resistant infection or systemic illness (see also Pyelonephritis):
• Ertapenem 1gm IV q24h
• Piperacillin-tazobactam 3.375 gm IV q6h
• Cefepime 2 gm IV q12h
• Ceftazidime-avibactam 2.5 gm IV q8h
• Plazomicin 15 mg/kg IV q24h
UTI, Complicated or Catheter-related

41. Empirical therapy - The approach to empiric therapy of acute
complicated UTI depends on the severity of illness, the risk factors for
resistant pathogens, and specific host factors.
Consider empiric treatment of STIs in patients with isolated urethritis, prostatitis, or
suspected pelvic inflammatory disease.
Treatment regimens for UTI in men should include antibiotics that are able to
penetrate prostate tissue (e.g., fluoroquinolones or TMP/SMX). Fosfomycin or nitrofurantoin are
generally not adequate.
To reduce false-positive results, avoid sampling urine for culture from previously inserted
catheters or collection bags, as these sites are frequently colonized by bacteria within a few
hours of catheter insertion.

45. Outpatient

47. Critical illness/urinary tract obstruction - For patients who are critically ill
or have urinary tract obstruction, we suggest an antipseudomonal
carbapenem (meropenem or imipenem) plus vancomycin .These patients
are at high risk of adverse outcomes if empiric antimicrobial therapy is
insufficient, and these regimens cover multidrug-resistant organisms, which
are increasing in prevalence. In locations where the community prevalence
of multidrug-resistant organisms is known to be low, regimens with a
narrower spectrum (as suggested for other hospitalized patients) may be
appropriate.
Urinary tract obstruction, if present, requires decompression.

51. Other hospitalized patient - For hospitalized patients without critical
illness or urinary tract obstruction who have no risk factors for a multidrug-
resistant (MDR) gram-negative infection , we
suggest ceftriaxone or piperacillin-tazobactam. Oral or parenteral
fluoroquinolones are also reasonable options. For patients who have risk
factors for an MDR gram-negative infection, we suggest piperacillin-
tazobactam, cefepime, or an antipseudomonal carbapenem. For those with
a recent history of an extended-spectrum beta lactamase (ESBL)-
producing urinary isolate specifically, we use a carbapenem.

56. Out patients without risk for resistance - For outpatients without risk
factors for an MDR gram-negative infection, we suggest an oral
fluoroquinolone, such as levofloxacin or ciprofloxacin. If the community
prevalence of E. coli fluoroquinolone resistance is known to be higher than
10 percent, we also suggest a single dose of a long-acting parenteral
agent such as ceftriaxone or ertapenem prior to administering the
fluoroquinolone. If there are concerns about intolerance or adverse effects
with fluoroquinolones, other options include giving a long-acting parenteral
agent followed by either trimethoprim-sulfamethoxazole or an oral beta-
lactam, or continuing the parenteral agent until susceptibility testing results
return.

61. Outpatients with risk for resistance
For outpatients with risk factors for an MDR gram-negative infection, we
suggest an initial dose of ertapenem. Subsequently, an oral
fluoroquinolone or daily ertapenem can be used.
Asymptomatic bacteriuria in pregnancy is a risk factor for pyelonephritis and should be treated.

66. Directed therapy and duration
Urine culture and susceptibility testing results should be used to tailor the
regimen to a more narrow-spectrum agent, if appropriate. Parenteral
regimens can also be switched to an active oral agent following symptom
improvement. Appropriate oral agents to treat acute complicated UTI
include fluoroquinolones (e.g., levofloxacin or ciprofloxacin) for 5 to 7 days
or trimethoprim-sulfamethoxazole for 7 to 10 days. Oral beta-lactams
(e.g., amoxicillin-clavulanate, cefpodoxime, or cefadroxil) for 7 to 10 days
are less effective for acute complicated UTI but are appropriate
alternatives if susceptibility is documented and the other agents are not
feasible.

69. Urologic issues - Patients who have underlying anatomical or functional
urinary tract abnormalities (including neurogenic bladder, indwelling
bladder catheters, nephrostomy tubes, urethral stents) may warrant
additional management, such as more frequent catheterization to improve
urinary flow, exchange or removal of a catheter, and/or urologic or
gynecologic consultation.

71. Do you have any questions?

72. Resources
● Pocket Medicine
● Uptodate
● Dynamed
● Amboss
● Osmosis
● Bmj
● Sanfordguide