UTI

Question 1

What defines an uncomplicated UTI?

Answer 1

A UTI occurring in a healthy, non-pregnant woman with normal genitourinary anatomy and function.

Question 2

What defines a complicated UTI?

Answer 2

• UTIs in males
• Pregnant women
• Immunocompromised patients
• Patients with urinary obstruction
• Patients with catheters
• Patients experiencing recurrent infections

Question 3

In a young nonpregnant female patient, there is dysuria, urinary frequency, urgency, and physical exam findings of suprapubic tenderness, but no fever, chills, or flank pain. These findings, along with the presence of pyuria, positive leukocyte esterase, and nitrites on urinalysis, are suggestive of … ?

Answer 3

uncomplicated acute cystitis.

Question 4

What is the most common cause of UTIs?

Answer 4

Escherichia coli (Uropathogenic E. coli - UPEC), which is responsible for ~80% of cases.

Other causative organisms include Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus saprophyticus.

Question 5

What is the most common cause of acute cystitis?

Answer 5

• The most common cause for acute cystitis is Escherichia coli.
• Other less common pathogens include Proteus mirabilis and Klebsiella pneumoniae.

Question 6

What is the most common antibiotic resistance pattern seen in E. coli UTIs?

Answer 6

Increasing resistance to TMP-SMX and fluoroquinolones, especially in community-acquired infections.

Question 7

How does bacterial adherence contribute to UTI pathogenesis?

Answer 7

Uropathogenic E. coli (UPEC) express P fimbriae, allowing adherence to urothelial cells and evasion of immune defenses.

Question 8

What bacteria is commonly associated with UTIs in young, sexually active females?

Answer 8

Staphylococcus saprophyticus.

Question 9

Which bacteria is associated with struvite (staghorn) stones?

Answer 9

Proteus mirabilis (urease-producing, raises urine pH).

Question 10

What are the classic symptoms of acute UTI?

Answer 10

Dysuria and urinary frequency.

Question 11

What are the classic symptoms of acute cystitis?

Answer 11

Dysuria, urinary frequency, urgency, suprapubic pain, NO systemic symptoms.

Question 12

What symptoms suggest pyelonephritis?

Answer 12

Fever and costovertebral angle (CVA) tenderness are the main symptoms, while chills, flank pain, nausea, and vomiting may be accompanying symptoms.

Question 13

What are the characteristic urinalysis findings for UTIs?

Answer 13

Leukocyte esterase (WBCs), nitrites (gram-negative bacteria), hematuria, bacteriuria.

Question 14

When should urine culture be obtained in UTI patients?

Answer 14

In complicated UTIs, pregnancy, recurrent infections, treatment failure, or atypical symptoms.

Question 15

Which demographic is known to exhibit atypical symptoms of UTI?

Answer 15

1. Elderly Patients
2. Patients with Diabetes
3. Immunocompromised Patients (e.g., HIV, Chemotherapy, Transplant)
4. Catheterized Patients (CAUTI - Catheter-Associated UTI)

Question 16

While experiencing a UTI, what symptoms tend to be exhibited by the elderly patient population?

Answer 16

Altered mental status (confusion, delirium). Make sure to perform a urinalysis!

Question 17

While experiencing a UTI, what symptoms tend to be exhibited by patients with diabetes?

Answer 17

Patients with diabetes have a higher risk of complicated UTI, emphysematous pyelonephritis, and fungal UTI (e.g., Candida).

Question 18

While experiencing a UTI, what symptoms tend to be exhibited by patients who are immunocompromised?

Answer 18

These patients Increased have an increased risk of atypical or severe infections.

Question 19

What are the first-line antibiotics for uncomplicated UTIs?

Answer 19

Nitrofurantoin, TMP-SMX, or fosfomycin.

Question 20

Which antibiotics should be avoided in pregnancy for UTI treatment?

Answer 20

Fluoroquinolones (cartilage damage), TMP-SMX (neural tube defects in 1st trimester, kernicterus in 3rd trimester).

Question 21

What is the treatment for acute cystitis during pregnancy (and nonpregnancy)?

Answer 21

During pregnancy, physiologic changes such as increased urine output and compression of the bladder by the gravid uterus often cause symptoms of urinary frequency and urgency. However, dysuria and a urinalysis positive for bacteria and leukocyte esterase, is consistent with acute cystitis.

Other less common pathogens include Proteus mirabilis and Klebsiella pneumoniae. Risk factors for urinary tract infection in pregnancy include the presence of asymptomatic bacteriuria, nulliparity, pregestational diabetes mellitus, and tobacco use. Pregnant patients with clinically suspected acute cystitis are treated empirically with antibiotics. First-line antibiotics in nonpregnant patients include nitrofurantoin, trimethoprim-sulfamethoxazole, and fosfomycin. However, during pregnancy, first-line antibiotics include beta-lactams (eg, cefpodoxime, amoxicillin-clavulanate) and fosfomycin due to the safety profile of these antibiotics throughout the entirety of the pregnancy. Nitrofurantoin and trimethoprim-sulfamethoxazole can be used safely in the second trimester but are typically avoided near term (38-42 weeks gestation) in the third trimester. However, if no other antibiotic can be used (eg, patient allergy, treatment resistance), they are appropriate second-line regimens. A urine culture is obtained to confirm infection and direct modification of the antibiotic regimen should symptoms not improve with treatment. Because there is a high risk for persistent bacteriuria, a urine culture is repeated for a test of cure one week after treatment completion.

Question 22

What is the preferred antibiotic for pyelonephritis requiring hospitalization?

Answer 22

IV ceftriaxone or gentamicin (aminoglycoside).

Question 23

What is the preferred treatment for UTI in pregnancy?

Answer 23

Amoxicillin-clavulanate, cephalexin, or fosfomycin.

Question 24

What is the duration of antibiotic therapy for uncomplicated UTI?

Answer 24

3-5 days.

Question 25

What is the duration of antibiotic therapy for complicated UTI?

Answer 25

7-14 days.

Question 26

What is the recommended prophylaxis for recurrent UTIs?

Answer 26

Daily or postcoital low-dose antibiotics (TMP-SMX, nitrofurantoin, cephalexin).

Question 27

What are indications for renal imaging in UTI patients?

Answer 27

Persistent fever after 72 hours of treatment, history of stones, recurrent infections, obstructive symptoms.

Question 28

What is the next step if a patient with a UTI does not improve on antibiotics?

Answer 28

Obtain a urine culture and renal ultrasound or CT to rule out abscess or obstruction.

Question 29

A USMLE question describes a febrile patient with flank pain, hypotension, and tachycardia. What is the next step?

Answer 29

Start IV fluids and broad-spectrum antibiotics (e.g., piperacillin-tazobactam, cefepime, or meropenem if MDR pathogens are suspected).

Question 30

A male patient has a UTI. What should always be considered?

Answer 30

Prostatitis or an underlying anatomical abnormality (e.g., BPH, strictures).

Question 31

A pregnant patient has asymptomatic bacteriuria. What is the next step?

Answer 31

Treat with pregnancy-safe antibiotics (amoxicillin-clavulanate, cephalexin) to prevent pyelonephritis and preterm labor.

Question 32

A diabetic patient has recurrent UTIs. What complication should be suspected?

Answer 32

Emphysematous pyelonephritis (gas-forming bacteria, often requires nephrectomy).

Question 33

A catheterized patient develops fever and leukocytosis. What is the next step?

Answer 33

Remove the catheter and obtain a urine culture before initiating antibiotics.

Question 34

What is the number needed to treat (NNT) for antibiotic prophylaxis in recurrent UTI?

Answer 34

NNT = ~7-8 for preventing recurrence in women with ≥3 UTIs per year.

Question 35

A 46-year-old woman presents to the emergency department for evaluation of burning with urination for the past three days. Yesterday, the patient also developed right-sided flank pain and chills. She has no significant past medical history and takes no medications. Temperature is 38.2 °C (100.8 °F), pulse is 110/min, blood pressure is 95/50 mmHg, respirations are 14/min, and oxygen saturation is 100% on room air. On physical examination, there is tenderness to palpation at the right costovertebral angle. The abdomen is soft and nondistended. Pregnancy test is negative. The serum leukocyte count is 18,000/mm3 , and serum creatinine is 0.8 mg/dL. Urinalysis, urine culture, and blood cultures are obtained. Urinalysis is shown below. IV fluids are administered. Which of the following is the most appropriate next step in management? A) Start oral nitrofurantoin B) Repeat urinalysis C) Start norepinephrine infusion D) Perform cystoscopy E) Start intravenous ceftriaxone

Answer 35

Patients with pyelonephritis present with fever, flank pain, costovertebral angle (CVA) tenderness, and urinalysis indicative of infection. Patients with uncomplicated pyelonephritis can be treated as outpatients. While patients with complicated pyelonephritis require hospitalization and typically a urology consultation. Any patients with pyelonephritis who are unstable require stabilization and inpatient treatment. Acute pyelonephritis is a urinary tract infection involving the kidneys, as opposed to cystitis which involves the bladder. Patients generally present with fever, chills, and flank pain and have CVA tenderness on palpation. Laboratory evaluation will likely show leukocytosis. If kidney function is deranged, then creatinine may be elevated. Urinalysis will show bacteriuria and pyuria and may show hematuria or white blood cell casts. Nitrites may be seen if E. coli is the causative pathogen. Urine and blood cultures should be obtained. This patient with acute pyelonephritis is unstable with urosepsis, and should be admitted to the hospital for IV fluids, V cetriaxone, and further workup. Pyelonephritis can be classified as uncomplicated or complicated. Complicated pyelonephritis is diagnosed when certain host factors exist like immunosuppression or the presence of comorbidities like diabetes mellitus or when structural factors exist like obstruction from nephrolithiasis or renal abscess. Uncomplicated pyelonephritis in a stable patient can be treated as an outpatient if the patient can tolerate oral antibiotics (e.g. ciprofloxacin) and oral hydration and has no significant medical comorbidities. If the patient has medical comorbidities, is very ill, or cannot tolerate oral medication or hydration, they require hospitalization for intravenous antibiotics (e.g., ceftriaxone, piperacillin-tazobactam). Complicated pyelonephritis is associated with urinary system pathologies such as urolithiasis (kidney or ureteral stones, renal abscess, or perinephric (perirenal) abscess and also with host factors like male sex and immunosuppression. These patients need hospitalization and intravenous antibiotics, a urology consult, and possibly an interventional radiology consult. Pyelonephritis in pregnant patients is also treated with hospitalization and IV antibiotics.

Question 36

A 32-year-old woman presents to her primary care physician with a 2-day history of dysuria, urinary frequency, and urgency. She is not experiencing fevers, chills, or flank pain. Her past medical history is unremarkable. She is not sexually active. Her vital signs are within normal limits. Physical examination is significant for suprapubic tenderness. Urinalysis is positive for nitrites and leukocyte esterase and reveals 25-30 WBCs and 6-8 RBCs. Which of the following is the best next step in management? A) Obtain urine culture and sensitivity B) Treat with oral ciprofloxacin C) Treat with oral nitrofurantoin D) Treat with IV ampicillin E) Treat with oral fluconazole

Answer 36

Once pregnancy has been ruled out in women of childbearing age with suspected acute uncomplicated cystitis, empiric treatment with oral nitrofurantoin, TMP-SMX, or fosfomycin should be started. This patient presents with dysuria, urinary frequency, urgency, and suprapubic tenderness on physical examination in the absence of fever, chills, and flank pain. These findings, along with the presence of pyuria, positive leukocyte esterase, and nitrites on urinalysis, are suggestive of uncomplicated cystitis. The most appropriate next step would be to treat empirically with oral nitrofurantoin. The management of uncomplicated cystitis in premenopausal women starts with pregnancy testing when the possibility of pregnancy cannot be excluded by history alone. Then empiric antibiotics should be started. Appropriate treatment includes oral nitrofurantoin for 5 days, trimethoprim-sulfamethoxazole (TMP-SMX) for 3 days, or a single dose of fosfomycin. Alternative options include fluoroquinolones or beta-lactams. If initial treatment fails to lead to improvement in symptoms, a urine culture is indicated to identify the causative organism and assess for antibiotic resistance. Another indication for obtaining a urine culture is if antibiotic resistance is highly likely such as in cases of recurrent UTis, recent antibiotic use, and recent hospitalization. Urine culture should be obtained in any cases of complicated UTls such as in patients with underlying urologic abnormalities or immunocompromising conditions. In cases of complicated lower UTls, alternative antibiotic choices and longer treatment durations may be necessary. Obtaining a urine culture and sensitivity test prior to initiating antibiotic therapy is indicated in these situations to guide antibiotic selection and ensure effective treatment. Fluoroquinolones or 3rd or 4th generation cephalosporins are considered the treatment of choice for complicated lower UTls. If the patient is pregnant, it is important to avoid teratogenic antibiotics such as tetracycline, fluoroquinolones, and TMP-SMX and to send a urine culture.

Question 37

A 62-year-old man presents to the emergency department with two days of fever, vomiting, and right flank pain. The pain is intermittent and has not responded to acetaminophen or ibuprofen. The patient also had burning urination that started around the same time, which he attributed to a new body soap. Temperature is 38.5 °C (101.3 °F), pulse is 108/min, blood pressure is 145/88 mmHg, respiratory rate is 18/min, and SpOz is 99% on room air. On physical examination, the patient has no periumbilical or suprapubic tenderness to palpation. The serum leukocyte count is 19,000/mm' . Urinalysis shows positive leukocyte esterase, moderate pyuria, and the presence of white blood cell casts. Which of the following physical exam maneuvers will most likely elicit pain in this patient? A) Elevation of the patient's right foot and striking the right heel while the patient is supine B) Flexion and internal rotation of the right hip while the patient is supine C) Palpation and percussion between the right 12th rib and spine D) Passive extension of the right hip while the patient lies on their left side E) Palpation in the left lower quadrant and waiting for report of pain in the right lower quadrant

Answer 37

Patients with pyelonephritis present with fever, flank pain, leukocytosis, and urine studies indicating infection. Tenderness to palpation and percussion at the costovertebral angle is highly suggestive of pyelonephritis and can help make the diagnosis in the right clinical scenario. This patient with fever, flank pain, dysuria, leukocytosis, and urinalysis positive for pyuria and white blood cell casts most likely has acute pyelonephritis. Pyelonephritis is a urinary tract infection involving the kidney. Laboratory evaluation of such a patient shows leukocytosis. When kidney function is deranged, creatinine may be elevated. Urinalysis reveals bacteriuria and pyuria and may show hematuria or white blood cell casts. Urine and blood cultures should be obtained. Patients generally present with fever, chills, nausea, vomiting, and flank pain. Some patients may have difficulty describing the pain and may describe it as back or abdominal pain. Some patients have dysuria or urinary urgency/frequency during or before the onset of flank pain. Tenderness to palpation or percussion at the costovertebral angle (CVA), which is the area between the 12th rib and the spine,, is highly suggestive of acute pyelonephritis in the right clinical scenario. This patient will likely have significant CVA tenderness to palpation and percussion.

Question 38

A 43-year-old woman is hospitalized for fever, nausea, vomiting, right flank pain, and dysuria. After an initial evaluation, acute pyelonephritis is diagnosed, and the patient is started on intravenous ceftriaxone. The initial serum leukocyte count is 23,000/mm^3. Urine culture grows > 100,000 colony-forming units of E. coll, which are susceptible to ceftriaxone. On hospital day three, the patient develops a fever after being afebrile for 24 hours. Flank pain is still present. Current temperature is 38.5 °C (101.3 °F), pulse is 86/min, and blood pressure is 138/81 mmHg. Serum leukocyte count is 21,000/mm^3. Significant tenderness to palpation is still present at the right costovertebral angle. Which of the following is the best next step in management? A) Change ceftriaxone to cefepime B) Obtain a serum lactate level C) Obtain abdominal MRI D) Obtain CT of the abdomen and pelvis E) Obtain a repeat urine culture

Answer 38

Patients with uncomplicated pyelonephritis can be treated in the outpatient setting as long as they are not severely ill with high fevers and persistent pain, can take oral medications and hydration, and have no significant comorbidities. Patients with severe or complicated pyelonephritis should be treated as inpatients. This patient with acute pyelonephritis is not improving on appropriate antibiotics. Lack of improvement within 48 to 72 hours of initiation of treatment suggests that the antibiotic choice is incorrect (empiric antibiotic does not cover the pathogen that grows out or there is bacterial resistance to an appropriate antibiotic) or that the source of the infection must be controlled (calculus or obstruction, renal or perinephric abscess that needs intervention). This patient's infection is sensitive to the antibiotic being used. The issue is likely a lack of source control, which raises concern for complicated pyelonephritis (e.g., abscess) requiring further imaging and possible intervention. CT of the abdomen and pelvis is generally used to diagnose physiologic or anatomical features leading to complicated pyelonephritis. If CT is not available or the patient cannot undergo radiation (e.g. a pregnant woman), ultrasound can often be used. Patients with mild to moderate acute uncomplicated pyelonephritis can be treated as outpatients if they can tolerate oral antibiotics (e.g. ciprofloxacin) and oral hydration. If the patient has medical comorbidities (especially diabetes) or is very ill with persistently high fevers, severe pain, or the inability to take medications or hydrate orally, they require hospitalization for intravenous antibiotics (e.g., ceftriaxone, piperacillin-tazobactam). Complicated pyelonephritis is associated with urolithiasis (kidney or ureteral stone), anatomic or functional urinary tract abnormalities, renal or perinephric (perirenal) abscess, recent urological manipulations, underlying immunosuppression, and male sex. These patients need hospitalization, V antibiotics, and a urology consultation for possible cystoscopy and intervention. If patients on outpatient treatment are not improving, they should be admitted and started on intravenous antibiotics and hydration. Hospitalized patients, like the patient in this case, should have abdominal imaging if they are not improving despite 48 to 72 hours of appropriate antimicrobial therapy.