Episode 69 – Urinary Tract Infections

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We cover Free Open Access Medical Education (FOAM) from a recent Emergency Medicine Cases podcast and First10inEM blog post by Dr. Justin Morganstern regarding urinary tract infections (UTIs).   This podcast and blog tackle common issues in UTI diagnosis and treatment, including the following points:

  • UTI is a clinical diagnosis, a dirty urine does not mean the patient has a UTI
  • Urinalyses are more complicated to interpret than we probably understand

The Core Content

Rosen’s Emergency Medicine (8th ed), Chapter 99; Tintialli’s Emergency Medicine (8th ed), Chapter 91; IDSA Guidelines for Treatment and Asymptomatic Bacteriuria

UTI diagnosis

Asymptomatic bacteriuria

UTI Treatment

Rosh Review Emergency Board Review Questions

A 6-year-old girl presents with 4 days of lower abdominal pain. The patient complains of dysuria. On exam, the patient is afebrile and has mild tenderness to palpation in the suprapubic area. No costovertebral tenderness is elicited on exam. A clean-catch urine sample is sent for urinalysis. If positive, which of the following is the most specific to confirm the diagnosis?

A. Glucose

B. Leukocyte esterase

C. Nitrites

D. WBCs (>5 per high power field)

Answer

C. The patient’s presentation is consistent with an uncomplicated urinary tract infection (UTI). The most common cause of a UTI in children >1 year of age is E. coli. Nitrites normally are not found in urine but result when bacteria reduce urinary nitrates to nitrites. Many Gram-negative and some Gram-positive organisms are capable of this conversion, and a positive dipstick nitrite test indicates that these organisms are present in significant numbers (i.e., more than 10,000 per mL). This test is specific (92%–100%) but not highly sensitive (19%–48%). A positive result is helpful, but a negative result does not rule out UTI. The nitrite dipstick reagent is sensitive to air exposure, so containers should be closed immediately after removing a strip. After 1 week of exposure, 33% of strips give false-positive results, and after 2 weeks, 75% give false-positive results. Non-nitrate-reducing organisms also may cause false-negative results, and patients who consume a low-nitrate diet may have false-negative results.

Glucose (A) normally is filtered by the glomerulus, but it is almost completely reabsorbed in the proximal tubule. Glycosuria occurs when the filtered load of glucose exceeds the ability of the tubule to reabsorb it (i.e., 180–200 mg per dL). Etiologies include diabetes mellitus, Cushing’s syndrome, liver and pancreatic disease, and Fanconi’s syndrome. Leukocyte esterase (B) is produced by neutrophils and may signal pyuria associated with UTI. It has a sensitivity of 72%­–97% and specificity of 41%–86%. Leukocyte casts in the urinary sediment can help localize the area of inflammation to the kidney. Organisms such as Chlamydia and Ureaplasma urealyticum should be considered in patients with pyuria and negative cultures. Other causes of sterile pyuria include balanitis, urethritis, tuberculosis, bladder tumors, viral infections, nephrolithiasis, foreign bodies, exercise, glomerulonephritis, and corticosteroid and cyclophosphamide use. Leukocytes (D) may be seen under low- and high-power magnification. Men normally have fewer than 2 white blood cells (WBCs) per HPF; women normally have fewer than 5 WBCs per HPF; >5 WBCs/HPF is associated with a 90%–96% sensitivity and 47%–50% specificity.

A 24-year old woman presents with URI symptoms. She is 32 weeks pregnant. As part of her work-up, you order a urinalysis, which shows 2+ bacteria with no WBCs. Two days later, the lab calls you and informs you that the urine culture is positive. You call the patient back and she denies symptoms of urinary tract infection. With regards to the urine culture results, what treatment is indicated?

A. Cephalexin 500 mg QID for 7 days

B. Ciprofloxacin 500 mg QID for 7 days

C. No treatment is necessary

D. Trimethoprim-sulfamethoxazole 1 DS tablet BID for 3 days

Answer

A. The patient has asymptomatic bacteriuria of pregnancy confirmed by a positive urine culture and should be treated with an oral antibiotic that is known to be safe in pregnancy, such as cephalexin 500 mg QID for 7 days. Asymptomatic bacteriuria is common in the general population and in most scenarios does not require therapy. However due to the high risk of complication seen during pregnancy, it should be treated with antibiotics. It is seen in 2-10% of pregnant women and is commonly due to E. coli. Pregnant women have an increased risk of developing urinary tract infections due to the pressure that the enlarged uterus exerts on the ureters and bladder, incomplete emptying during voiding and impaired ureteral peristalsis from progesterone-induced relaxation of the ureteral smooth muscle. Complications of untreated asymptomatic bacteriuria include development of a lower urinary tract infection, pyelonephritis, renal abscess, renal failure, bacteremia, sepsis, intrauterine growth retardation, premature labor and neonatal death. Treatment options generally include cephalosporins, such as cephalexin, amoxicillin (or amoxicillin-clavulanate) and nitrofurantoin. All of which are recognized as Category B by the Food and Drug Administration; meaning that animal studies have failed to show a risk to the fetus. Treatment duration should be for 7-10 days.

Ciprofloxacin (B) and trimethoprim-sulfamethoxazole (D) are Category C and D, respectively, and therefore should be avoided in pregnancy when possible. Because there is increased risk for complication during pregnancy, antibiotic treatment (C) is recommended.

References:

Gupta K et al. 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.  Infect Dis (2011) 52 (5): e103-e120.

Nicolle L et al. Infectious Diseases Society of America Guidelines for the Diagnosis and Treatment of Asymptomatic Bacteriuria in Adults.   Infect Dis (2005) 40 (5): 643-654.

Rosen’s Emergency Medicine, 8th ed. Chapter 99.

Tintinalli’s Emergency Medicine, 8th ed.  Chapter 91.

Episode 68 – Ischemic Electrocardiograms

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The Free Open Access Medical Education (FOAM)

In the United States, electrocardiograms (ECGs) performed in triage must often be signed by an attending emergency physician shortly after they are performed.  This creates a significant number of interruptions which are not only inconvenient but also distracting for physicians taking care of patients.  A recent study in Academic Emergency Medicine by Hughes and colleagues looks at the potential clinical relevance of having emergency physicians sign ECGs read “normal” by the computer software.  FOAM reviews of this article can be found here:

Triage ECGs

The Core Content

Rosen’s Emergency Medicine (8th ed), Chapter 78 and the 2013 AHA Guidelines

ST Elevation MI (STEMI) 

This is the time-dependent infarction with current goals to obtain reperfusion within 90 minutes (or 60 minutes at some hospitals).

STEMI

However, there are more kinds of ischemia than just STEMI and many of these can be subtle. Close examination of even normal ECGs is necessary.

T wave Ischemia

STEMI mimics

Rosh Review Emergency Board Review Questions

A 45-year-old man presents with chest pain. Which of the following features most strongly predicts acute coronary syndrome as the cause of his chest pain

A. History of diabetes mellitus, hypertension, and tobacco use

B. Pleuritic pain

C. Pressure-like pain

D. Radiation to the right arm

Answer

D.

Chest pain is one of the most common presenting complaints to emergency departments. The causes of chest pain are varied and range from benign (e.g. muscle strain, costochondritis, pleurisy) to life-threatening (e.g. acute coronary syndrome, aortic dissection, pulmonary embolism). The emergency provider’s job is to carefully assess the patient with chest pain and rule out any life-threatening etiologies. As such, acute coronary syndrome must be considered on the differential of every patient presenting with chest pain. Acute coronary syndrome most commonly occurs when an atherosclerotic plaque is disrupted or eroded, resulting in platelet aggregation and thrombus formation at the site, resulting in diminished or absent flow within the affected vessel. Historical features are extremely important in helping categorize patients as low, moderate, or high risk for acute coronary syndrome, and performing a detailed history regarding chest pain complaints is critical. Low risk features include pleuritic, positional, reproducible, and sharp or stabbing pain. In addition, non-exertional pain and pain localized to a small inframammary area have a low likelihood of being cardiac in etiology. High risk features include chest pressure (positive likelihood ratio [LR+] 1.3), pain similar to prior cardiac pain (LR+ 1.8), and associated vomiting or diaphoresis (LR+ 1.9 and 2.0, respectively). The highest risk features include radiation to the right arm or shoulder (LR+ 4.7), left arm (LR+ 2.3), or both arms or shoulders (LR+ 4.1), and exertional chest pain (LR+ 2.4). Of the above choices, radiation to the right arm is the strongest predictor of a cardiac etiology of chest pain.

History of diabetes, hypertension, and tobacco use (A) are traditional cardiac risk factors that predict the lifetime risk of developing coronary artery disease. However, these risks factors are less helpful than historical features in predicting whether an acute presentation of chest pain is due to acute coronary syndrome. Pleuritic pain (B) is not a strong predictor of acute coronary syndrome. Pressure-like pain (C) is a high-risk feature but is less predictive or acute coronary syndrome than pain that radiates to the right arm.

References:

  1. Hughes KE, Lewis SM, Katz L, Jones J. Safety of Computer Interpretation of Normal Triage ECGs. Acad Emerg Med. 2016
  2. O’gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013;61(4):e78-140.

Episode 67 – Serious Pediatric Fever

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We cover an episode of The Skeptic’s Guide to Emergency Medicine that covers a validation study of the Step by Step approach to pediatric fever.  This approach to infants with a fever <3 months old is alluring as it does not necessitate a lumbar puncture.  This algorithm had a better sensitivity and negative predictive value than the Rochester criteria.   The approach did miss some infants with a serious bacterial infection and these tended to be those between 21 and 28 days old and those with fever onset <2 hours prior to arrival.

Step by Step for Pedi Fever

 Core Content

We cover Chapter 116 in Tintinalli’s Emergency Medicine (8th ed) and Rosen’s on pediatric fever.

Infants <3 months old with fever algorithms

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Rosh Review Emergency Board Review Questions

A 25-day-old female presents with fever and cough. Mom denies any symptoms at home. The patient’s 2-year-old brother had a cough and rhinorrhea 1 week prior. On exam, the patient’s temperature is 38.7°C with clear lungs, a benign abdomen, and normal tympanic membranes bilaterally. What is the appropriate workup for this patient?

  1. CBC, chest X-ray
  2. CBC, chest X-ray, urinalysis
  3. CBC, chest X-ray, urinalysis, blood cultures
  4. CBC, chest X-ray, urinalysis, blood cultures, lumbar puncture
Answer

4.  Neonates with fever aged 28 days or younger may have few clues on history and physical examination to guide therapy. Therefore, a high index of suspicion is necessary to detect the febrile neonate with a serious bacterial infection. Obtaining the pertinent medical history from the mother regarding the pregnancy, delivery, and early neonatal life of the febrile neonate is essential. Typically, infections in the 1st week of life are secondary to vertical transmission, and those infections after the 1st week are usually community acquired or hospital acquired. Bacterial meningitis is more common in the 1st month of life than at any other time. An estimated 5%–10% of neonates with early onset group B streptococcal (GBS) sepsis have concurrent meningitis. Therefore, febrile infants (temperature >38°C) younger than 28 days should receive a full sepsis workupCBC, chest X-ray (A), urinalysis (B), and blood cultures (C) are a partial workup for neonatal fever.

A two-day-old boy presents to the ED with fever for the past four hours. His birth history includes a normal spontaneous vaginal delivery at term. Parents report noticing that the child “felt warm,” and that he was having copious nasal secretions while feeding. On physical examination, the child appears lethargic, has mottled extremities, and is hot to the touch. Breath sounds are clear bilaterally, and there are no rashes. His vital signs are T 102.9°F, BP 74/48 mm Hg, HR 170 beats per minute, and RR 40 breaths per minute. Which of the following groupings of organisms should your antibiotic choices cover when treating this febrile neonate?

  1. Listeria monocytogenes, Group B streptococcus, Escherichia coli
  2. Mycoplasma pneumoniae, Neisseria meningitidis, Streptococcus pneumoniae
  3. Neisseria meningitidis, Listeria monocytogenes, Streptococcus pneumoniae
  4. Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae
    Answer

Answer 1. The febrile neonate is a child 28 days and younger who presents with a fever. These children are at very high risk of serious bacterial infections, including urinary tract infection, pneumonia, meningitis, and bacteremia. Risk factors for serious bacterial infection in a neonate include prematurity, low birth weight, premature or prolonged rupture of membranes, meconium aspiration, or maternal group B streptococcus infection. The evaluation of a neonate with a fever includes CBC, urinalysis, blood culture, urine culture, and a lumbar puncture in order to obtain CSF for cell count, Gram stain, and culture. If the child has respiratory symptoms, a chest X-ray should be performed. If the child has diarrhea, stool testing should also be performed. The most common pathogens involved in serious bacterial infections, including meningitis and bacteremia, in neonates are Listeria monocytogenes, Group B streptococcus, and Escherichia coli. These children can become critically ill very rapidly; therefore, initial management should include a fluid bolus of 20 mL/kg and broad-spectrum antibiotics to cover the most common pathogens in this age group. The most appropriate antibiotics to use in neonates with a fever are ampicillin and cefotaxime. Ampicillin will cover Listeria monocytogenes while cefotaxime will cover Group B streptococcus and Escherichia coli. If there is a history of maternal infection with herpes simplex virus, acyclovir should be added to the empiric broad-spectrum treatment. These patients universally need to be admitted to the hospital for IV antibiotics and observation until all cultures have returned.  Mycoplasma pneumoniae, Neisseria meningitidis, Streptococcus pneumoniae (B) are common pathogens seen in adolescents and young adults. Mycoplasma pneumoniae is a common cause of atypical pneumonia in this age group. Streptococcus pneumoniae is a common bacterial cause of pneumonia, bacteremia, and meningitis while Neisseria meningitidis is primarily a cause of meningitis. Neisseria meningitidis, Listeria monocytogenes, Streptococcus pneumoniae (C) are the primary pathogens causing serious bacterial infections in adults over the age of 65. Listeria monocytogenes is a pathogen that is seen in infants and then later reemerges as a prominent pathogen in older adults. Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae (D) are the most common pathogens causing serious bacterial infections in children ages one to five years. There has been a significant decline in the incidence of Haemophilus influenzae type B in recent years due to childhood vaccination programs.