iTunes or Listen Here

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

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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.

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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

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***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.

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References:

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”

iTunes or Listen Here

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

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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.

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References

1. “Misconceptions about Seasonal Flu and Flu Vaccines”. CDC. Available at: https://www.cdc.gov/flu/about/qa/misconceptions.htm
2. “Influenza Antiviral Medications: Summary for Clinicians.” CDC. Available at https://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm
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.