Lyme Disease (Borreliosis)

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We cover a JAMA Clinical Reviews podcast on lyme disease, including some myth-busters.

  • Doxycycline can be used, safely, in kids < 8 years old [1].
  • Testing for lyme is a mess because :
    • (1)  we test patients with an ultra low probability of disease
    • (2) we test patients who shouldn’t be tested (i.e. have erythema migrans and thus very high probability)
    • (3) the tests are a pain to interpret and many clinicians (42.4% in lyme endemic Vermont) misinterpret tests, most commonly as false positive [2].
  • Lyme disease is spreading further south and west in the US, into Canada, and it’s also increasingly found in Europe [3,4].


Rosh Review Emergency Board Review Questions

A 32-year-old man with a history of hypertension and sickle cell disease presents to the ED for intermittent fevers. He has been feeling ill for the past few weeks with intermittent headaches, night sweats, and abdominal pain. He recently returned from Maine after a trip to see the fall colors. His vital signs are only remarkable for a temperature of 100.7oF. Physical exam reveals mild scleral icterus and hepatomegaly. The patient’s Wright stain shows intraerythrocytic rings. What co-infection is common in this disease?

A. Babesia microti

B. Borrelia burgdorferi

C. Francisella tularensis

D. Rickettsia rickettsii


A.This patient’s presentation is consistent with acute babesiosis infection. Patients are commonly co-infected with Borrelia burgdorferi (Lyme disease) or ehrlichiosis. Risk factors include functional or surgical asplenia, immunocompromised state, and advanced age. This patient likely has functional asplenia given his age and history of sickle cell disease. Diagnosis is confirmed with a Wright or Giemsa stain showing intraerythrocytic rings, similar to malaria. Babesiosis is due to Babesia parasite and transmitted via the Ixodes deer tick. Patients present with a wide array of symptoms from a vague viral syndrome-type symptoms and spiking fevers to hepatomegaly and hemolytic anemia. Patients with risk factors tend to have more severe features including severe hemolysis, jaundice, renal failure, and acute respiratory distress syndrome. Treatment is with atovaquone and clindamycin or azithromycin.


Which of the following would be the best antibiotic choice for first-line treatment of a 5-year-old who presents to your office with multiple erythema migrans lesions but no cardiac or neurological symptoms?

A. Amoxicillin PO for 14 to 21 days

B. Azithromycin PO for 14 to 21 days

C. Doxycycline PO for 10 to 21 days

D. Ceftriaxone IM for 14 days


***This is an example of the difference between practice and board exams, which tend to lag behind current knowledge.

Correct-Answer: Amoxicillin PO for 14 to 21 days. Lyme disease is a tick-borne illness that is caused by Borrelia burgdorferi, making it a spirochetal infection. When deciding the medical therapy for Lyme disease, staging is important. Early localized disease usually presents with a “bullseye rash,” otherwise known as erythema migrans. Patients in this stage of disease may have a few constitutional symptoms, such as fever, fatigue, headache, and myalgias. Early disseminated disease is present if patients have multiple erythema migrans, cardiac or neurologic findings. Late disease usually involves persistent arthritis of a large joint or more severe neurological findings such as encephalopathy or polyneuropathy. In the case above, amoxicillin is the best choice of treatment because the patient is under 8 years of age, and, while multiple lesions are present, the patient does not have neurological or cardiac involvement and should be treated with the same therapy as if he had a single lesion. Recommended duration of therapy is between 14 and 21 days. The goal of therapy is to reduce the risk of developing late Lyme disease and to shorten the duration of symptoms. Azithromycin PO for 14 to 21 days (B) is not recommended as a first-line treatment for Lyme disease because it is less effective than amoxicillin. There has been documented resistance to macrolides by some strains of Borrelia burgdorferi. Doxycycline PO for 10 to 21 days (C) is not recommended in this case because of the patient’s age. Tetracyclines are not recommended for children under 8 years of age because they can lead to permanent staining of their teeth. Ceftriaxone IM for 14 days (D) is not recommended because oral antibiotics, such as doxycycline, are just as effective for treatment of erythema migrans and make for easier administration.



  1. Todd S et al. No Visible Dental Staining in Children Treated with Doxycycline for Suspected Rocky Mountain Spotted Fever. The Journal of Pediatrics. May 2015. Volume 166, Issue 5, Pages 1246–1251
  2. Conant JL, Powers J, Sharp G, Mead PS, Nelson CA. Lyme Disease Testing in a High-Incidence State: Clinician Knowledge and Patterns. Am J Clin Pathol. 2018;149(3):234-240.
  3. European Centre for Disease Prevention and Control Accessed 9.22.2018
  4. Infectious Disease Society of America’s  2006 Lyme Guidelines
  5.  Min Han J et al. Comparative effectiveness and toxicity of oral antibiotics for early Lyme disease associated with erythema migrans: a systematic review and network meta-analysis. ECCMID abstract . 2017.
  6. Tintinalli’s Emergency Medicine: A Comprehensive Review. Chapter 160 “Zoonotic infections.”
  7. Rosen’s Emergency Medicine. (8 ed) . Chapter 126 “Tickborne Illnesses”

Episode 78 – Influenza

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We tackle some free open access medical education from the CDC on the flu vaccine, including:

  • Recommendations that individuals with any severity of egg allergy (including anaphylaxis) receive the flu vaccine. The only modification that needs to occur is patients with a history of true anaphylaxis to eggs should be given the flu shot in a setting where they can be monitored by a healthcare professional if needed (i.e. a doctor’s office) [1]
  • It is very unlikely that the flu vaccine causes Guillan-Barre Syndrome (GBS). If there is any increase as a result of the flu shot, it is 1-2 in 1,000,000 [1]

Oseltamivir for Influenza

We review the CDC recommendations as well as evidence from a 2014 Cochrane Review [1,3]. The data from the most recent Cochrane review includes studies from Roche Pharmaceuticals (makers of oseltamivir) that were initially unpublished and only released with international pressure, and seemingly do not support the CDC recommendations.

Rosh Review Emergency Board Review Questions

A 74-year-old woman presents with complaints of fever, productive cough with bloody sputum, shortness of breath, and headache. These symptoms developed and worsened drastically over the past 3 days. She recently recovered from an influenza infection 1 week ago. Her medical history otherwise includes only well-controlled hypertension. Vital signs on presentation are as follows: T 39°F, HR 106, BP 110/75, RR 30, oxygen sat 95% RA. A chest radiograph is obtained and a subsequent CT scan of the chest demonstrates multiple cavitary lung lesions. Which of the following organisms is most likely responsible for this patient’s presentation?

A. Clostridum perfringens

B. Escherichia coli

C. Mycobacterium tuberculosis

D. Staphylococcus aureus

  1. This patient’s presentation of pneumonia with multiple cavitary lesions on imaging is consistent with a post-viral secondary necrotizing pneumonia. The most common organism in necrotizing pneumonia, particularly after a viral upper respiratory infection, is S. aureus. Necrotizing pneumonia is known to be caused by a specific S. aureus strain that produces Panton-Valentine Leukocidin (PVL). Often, this infection and the ensuing pneumonia that develops, is preceded by an influenza infection. Typically this S. aureus strain is also methicillin resistant. A CT of the chest with contrast is useful in diagnosis, and empiric therapy should be initiated promptly (vancomycin or linezolid, piperacillin/tazobactam). Surgical intervention may be necessary if complications develop – such as septic shock, gross hemoptysis and empyema. The following should be considered in the differential diagnosis of pulmonary cavitation: necrotizing pneumonia, lung abscess, septic pulmonary embolism, fungal/mycobacterial infection, vasculitis, primary/metastatic tumor, rheumatoid nodules, congenital cysts. Defining characteristics of necrotizing pneumonia include: preceding influenza infection, rapid onset and progressive symptom worsening, decreased WBC count, airway hemorrhages, respiratory failure, necrotic destruction of lung parenchyma, high mortality rate. A preceding viral infection brings a large number of immune cells to the lung tissue, such that when secondary bacterial infection strikes, there is a catastrophic activation and destruction of immune mediators that damage lung tissue and lead to necrotizing pneumonia.

Clostridial gas gangrene is a highly lethal necrotizing soft tissue infection of skeletal muscle caused by toxin- and gas-producing Clostridium species. Clostridium perfringens (A), previously known as Clostridium welchii, is the most common cause of clostridial gas gangrene (80-90% of cases). Escherichia coli (B) is one of the most frequent causes of many common bacterial infections, including cholecystitis, bacteremia, cholangitis, urinary tract infection (UTI), and traveler’s diarrhea, and other clinical infections such as neonatal meningitis and pneumonia. Mycobacterium tuberculosis (C) causes cavitary lung lesions in the upper lobes and clinically manifests as hemoptysis, weight loss and night sweats. It does not have any clinical correlation with influenza.


  1. “Misconceptions about Seasonal Flu and Flu Vaccines”. CDC. Available at:
  2. “Influenza Antiviral Medications: Summary for Clinicians.” CDC. Available at
  3. Jefferson T, Jones MA, Doshi P, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database Syst Rev. 2014;(4):CD008965.

Episode 69 – Urinary Tract Infections


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)


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


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.


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 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

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 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.