Facilitator Version
Module # 9 UTI/Pyelonephritis
Created by Dr. Richard Vestal May 2014
Objectives:
1. Understand the clinical features associated with a urinary tract infection and be
able to develop a differential diagnosis for such symptoms
2. Understand the utility of the various features of the urinalysis and urine culture in
diagnosing a urinary tract infection, and know when such tests are clinically
indicated
3. Understand the comorbid conditions that distinguish uncomplicated from
complicated urinary tract infections and be able to distinguish the differences in
managing these conditions
References:
1. Bent S et al (2002), Does this woman have an acute uncomplicated urinary tract
infection? JAMA, 287(20):2701
2. Pappas, PG (1991), Laboratory in the diagnosis and management of urinary tract
infections. Medical Clinics of North America, 75(2):313
3. Echols, RM (1999), Demographic, clinical and treatment parameters influencing the
outcome of acute cystitis. Clinical Infectious Diseases, 29(1):113
4. Hooton, TM (2012), Clinical Practice. Uncomplicated urinary tract infection, New
England Journal of Medicine, 366(11):1028-37
5. Gupta, K et al (2011), International clinical practice guidelines for the treatment of
acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the
Infectious Diseases Society of America and the European Society for Microbiology
and Infectious Diseases. Clinical Infectious Diseases, 52(5):e103
6. Geerlings, SE et al (2013), SWAB Guidelines for Antimicrobial Therapy of
Complicated Urinary Tract Infections in Adults. Stichting Werkgroep
Antibioticabeleid.
Case
A 27-year-old female presents to your clinic complaining of a two-day history of pain with
urination that started abruptly. The patient denies any fevers or chills. She is sexually active with
two male partners and uses barrier protection occasionally. She has noticed that her urine is
darker in color and that she is urinating more frequently, but denies any vaginal discharge,
redness or pruritus. She has had two similar episodes remotely several years ago, but did not
present for evaluation due to a lack of medical insurance. Both of these episodes resolved
spontaneously
Vitals: Temperature - 37.3°C, Pulse - 82, Blood Pressure - 118/74, Respirations - 16, O2 - 94%
ambient air
On physical exam, the patient is appropriately oriented. The abdominal exam is unremarkable.
The pelvic exam shows no erythema or abnormal discharge. No back pain is appreciated.
What is your differential diagnosis?
Acute uncomplicated cystitis should be the most likely diagnosis given the patients symptoms of
dysuria and frequency. The typical symptoms of acute uncomplicated cystitis include dysuria,
increased frequency, urgency, suprapubic pain and hematuria.
Other diagnoses to consider include Vaginitis/Urethritis/Pelvic inflammatory disease, Interstitial
cystitis a.k.a. Painful bladder syndrome and structural urethral abnormalities
What additional workup would you like to perform on this patient?
You can consider treating without testing at this point. The presence of one symptom of acute
cystitis (see above) represents a 50% probability of a UTI. The presence of both dysuria and
urgency (as is the case with our patient) is associated with a 90% probability of a UTI (in the
absence of vaginitis symptoms).[1]
However, many practitioners would evaluate via with urine dipstick or urinalysis.
Urine dipsticks provide information about the presence of leukocyte esterase (LCE), nitrite and
blood.
While the presence of LCE or nitrite on a dipstick is associated with a specificity of 82%, the
sensitivity of a dipstick is only 75% and is unlikely to be helpful in the evaluation of patients with
a strong pre-test probability as a negative result should not affect the patient’s outcome.[1]
Many providers would opt for a urinalysis at this point.
Based on your history and physical exam, you decide to defer STI testing. A urinalysis is
performed that shows large LCE, negative nitrite, >150 WBCs/HPF and 50 RBC/HPF and a
diagnosis of acute uncomplicated cystitis is made.
What significance does the presence or absence of LCE, nitrite and WBC play in the
diagnosis of acute uncomplicated cystitis?
LCE – The presence of LCE is highly sensitive (75-91%) for the diagnosis of a urinary tract
infection, but lacks specificity (41-87%), and can represent a false positive in a number of
scenarios, particularly contaminated urine samples.[2]
Nitrite – The presence of nitrite is poorly sensitive (34-42%) but highly specific (94-98%) for the
presence of a urinary tract infection. Nitrite would be expected to be positive in the presence of
enterobacteriaceae, but may not be positive with other commonly seen organisms. [2]
WBC – The presence of any WBC in the urine is highly sensitive (96%) for a urinary tract
infection, and the absence of urine WBC should prompt the search for alternative diagnoses,
though this can rarely be seen in the setting of unilateral pyelonephritis with obstruction. The
specificity of urine WBC is poor (47%).[2]
The presence of bacteria in the urine is poorly sensitive (58%) and specific (72%). [2]
The above values represent any positive value. Obviously if higher thresholds are used (i.e.,
many bacteria vs. few), the sensitivity decreases and specificity increases.
What are the most likely organisms contributing to this patient’s symptoms?
The most common organisms causing a urinary tract infection are as follows:[3]
Escherichia coli
Proteus mirabilis
Klebsiella pneumonia
Other enterobacteriaceae
Staphylococcus saprophyticus
Uncomplicated patients growing lactobacilli, enterococci, Group B streptococci and coagulasenegative staphylococci (other than saprophyticus) most likely represent contaminated
specimens.[4]
What is the most appropriate therapy for this patient? (medication and duration)
There are several antibiotic options for acute uncomplicated cystitis, though empiric therapy
must be based on local resistance patterns (see UNM 2012 antibiogram below). Acceptable
treatment options include:[5]


Trimethoprim-sulfamethoxazole (One DS tablet PO BID x 3 days)
-Avoid if local resistance is >20% or if the patient has taken TMP-SMX within the last 6
months
Nitrofurantoin (100mg PO BID x 5 days)
-Avoid if pyelonephritis is suspected
-Contraindicated in CrCl < 60




Fosfomycin (3gm PO x 1 dose)
Fluoroquinolone (three-day course of ciprofloxacin, levofloxacin or ofloxacin)
Oral beta lactams are less effective, but can be considered. These include amoxicillinclavulanate, cefpodoxime, cefdinir and cefaclor. Each for a seven-day course.
Note very high resistance rates of e.coli to TMP-SMX, amoxicillin-clavulanate and
ciprofloxacin with our local antibiogram
What conditions must be present to diagnose a complicated UTI and how would this affect
management?
1. Genitourinary/Renal abnormalities (i.e., renal disease, urinary obstruction,
genitourinary instrumentation [current or recent], functional abnormality, etc.)
2. High-risk for resistant organisms (Symptoms >7 days, hospital-acquired infection)
3. Immunosuppression (Diabetes, HIV, chronic steroid use, etc.)
4. Pregnancy
These patients are at risk for a much more broad spectrum of organisms, so a urine culture is
essential to help narrow the antibiotic regimen rather than completing a course of a very widespectrum antibiotic coverage. Acceptable antibiotic regimens until culture data is returned
includes:[6]
 Amoxicillin plus an aminoglycoside (10-14 days)
 Second-generation cephalosporin plus an aminoglycoside (10-14 days)
 Intravenous third-generation cephalosporin (10-14 days)
 Fluoroquinolones if local resistance is <10% (ciprofloxacin 500mg po BID or 1000mg
extended release PO QD; levofloxacin 750mg PO QD) for 5-14 days has a wider
spectrum of coverage and achieves good urinary levels.
Nitrofurantoin, TMP-SMX, fosfomycin and oral beta-lactams have poor activity against the
additional organisms seen in acute complicated cystitis.
The patient is started on nitrofurantoin to complete a five-day course. A follow-up nursing phone
call reveals that she was compliant with her medication and has had complete resolution of her
symptoms.
The presence of what signs or symptoms would favor a diagnosis of pyelonephritis over
cystitis, and how would this affect management?
1. Fever (<38.0) or chills
2. Nausea or vomiting
3. Flank pain or costovertebral angle tenderness
4. WBC casts on urine microscopy
Nitrofurantoin, fosfomycin and pivmecillinam do not achieve adequate renal levels, so the most
appropriate empiric antibiotic choices in pyelonephritis include:
1. Fluoroquinolone (unless resistance patterns are greater than 10%)
2. Trimethoprim-Sulfamethoxazole (unless resistance patterns are greater than 20%)
3. Extended spectrum beta-lactam (commonly a third- or fourth-generation cephalosporin,
but may include medications such as ampicillin/sulbactam or piperacillin/tazobactam)
4. Aztreonam if the patient has a severe allergy or contraindication against the above
antibiotic choices
MKSAP 16 Questions
ID Question 31:
Prevention of CA-UTI (Answer - A)
ID Question 32:
Diagnosis of CA-UTI (Answer - D)
ID Question 36:
Management of acute uncomplicated cystitis (Answer - D)
ID Question 71:
Management of pyelonephritis (Answer - B)
ID Question 106:
Prophylaxis of recurrent UTI (Answer - C)
Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to Dr.
Wendy Gerstein, Department of Medicine, VAMC (111), or give to Dr. Patrick Rendon,
Division of Hospital Medicine, UNM Hospital.
1) Topic of module:__________________________
2) On a scale of 1-5, how effective was this module for learning this topic? _________
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment below:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient curriculum
in general:
6) Please circle one:
Attending
Resident (R2/R3)
Intern
Medical student