The Curbsiders podcast

#78 ID Pearls with Paul Sax MD

January 15, 2018 | By

It’s a potpourri of Infectious Diseases with tips from expert, Dr Paul Sax, MD, Clinical Director of the Division of Infectious Diseases at Brigham and Women’s Hospital, and Professor of Medicine at Harvard Medical School. We discuss the man flu, the flu vaccine, travel medicine, malaria, lyme disease, post lyme syndrome, chronic lyme, shingles, cellulitis, abscesses, antibiotics, c diff, antibiotic associated diarrhea, the dangers of fluoroquinolones, why doxycycline is awesome, and more! Told you it was a potpourri. Dr Shreya P. Trivedi (@ShreyaTrivediMD) joins Matt and Paul as guest host.

Show Notes, MCQ by Shreya Trivedi, MD
Edited by Matthew Watto, MD
Infographics and cover image by Matthew Watto, MD

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Case from Kashlak Memorial: 60 year old African female visit the clinic after seeing news that the flu vaccine isn’t effective and wanted advice on travel vaccines and prophylaxis her upcoming travel to visit friends and relatives in Africa.  

Test yourself w/these Multiple Choice Questions (MCQ) before reading through the show notes! Answers at bottom of page.

Question 1: Which of the following does not preclude a patient from getting the flu vaccine?

  1. Severe nausea
  2. Anaphylaxis
  3. Fever
  4. Need for an epi pen

Question 2:  A middle aged female presents to clinic for an erythematous patch after returning from vacation to New Hampshire, which included outdoor activities such as biking and hiking. Which of the following is the most appropriate management:

  1. Enzyme immunoassay for lyme disease
  2. Prescribe doxycycline
  3. Prescribe clindamycin
  4. Refer to dermatology

Question 3: Which of the following signs or symptoms is NOT helpful in distinguishing Clostridium difficile from antibiotic associated diarrhea?

  1. Abdominal cramping
  2. Fever
  3. Use of probiotics
  4. Leukocytosis

Clinical Pearls:

  1. Flu vaccine’s estimated effectiveness was about 10% against the H3N2 strain in Australia, but was more effective for other strains. It is uncertain if the flu season in other countries will be similar to that of Australia and which strains will be prevalent.
    1. A study looking at hospitalized flu patients from 2013-2014 found that the patient who had received the flu vaccination had reduced deaths, intensive care unit (ICU) admissions, ICU length of stay, and overall duration of hospitalization (Clinical Infectious Diseases 2017)
  2. Patients with an egg allergy can get the flu vaccine unless their allergic reaction is  anaphylaxis, hypotension, severe nausea, vomiting, or need for epinephrine (CDC site).
  3. Flu vaccine in acute illness: Okay to give if ambulatory patient w/minor illness, but avoid if critically ill due to low likelihood of response. -Dr Sax
  4. Immunity to malaria wanes rapidly after leaving an endemic country and being in an area of no risk for 6 months or more (World Health Organization). Therefore, most cases of malaria seen are people who formerly lived in developed countries, who are now “visiting friends and relatives” (VFR)
  5. CDC travel website:
  6. Quick and dirty travel tips: Most need 1) malaria prophylaxis 2) antibiotics (abx) against traveler’s diarrhea for as needed use 3) typhoid immunization 4) Hepatitis A vaccination 1 month before travel. Note: Hepatitis A vaccine is highly effective vs. the typhoid vaccines, which are not very effective.
  7. Lyme: Clinical diagnosis. Likely if recent hiking, travel to endemic area, erythema migrans (EM), an erythematous patch that blanches and may or may not have central clearing. Treatment is doxycycline for disease involving skin, joints, or Bell palsy; ceftriaxone if carditis, meningitis (see figures).
  8. Lyme prophylaxis: Give doxycycline 200 mg po x 1 dose w/in 72 hours of tick attachment in endemic area, especially in warmer months. Ixodes = black-legged tick and mice are main carrier.
    1. Two-tiered testing for lyme: enzyme immunoassay (EIA) IgM and IgG, with lyme disease has a high false positive rate (high sensitivity, but not specific). If EIA is positive or equivocal, a more specific western blot IgG +/- IgM is recommended for confirmation (CDC on Lyme Testing).
    2. Lyme testing (continued): Often negative in acute setting when EM rash is present, but  after exposure to Lyme future testing will be positive for years.
  9. Ninety percent of patients reporting a penicillin allergy from childhood have outgrown it or were never allergic at all (DynaMed Plus PCN Allergy). This does NOT include patients whose reaction was anaphylaxis, DRESS syndrome or desquamative rashes (SJS, TEN).
    1. Cross reactivity between penicillin and cephalosporins ranges from 3-10%
    2. Have your patients get penicillin skin testing! You can remove the penicillin allergy from the patient’s chart!
  10. Black box warning fluoroquinolones (FQ): Think twice before starting a FQ outpatient! In 2016, FDA advised against routine use of FQs for acute bacterial sinusitis, acute bacterial exacerbation of chronic bronchitis and uncomplicated urinary tract infections (FDA warning). Risks include: rare potentially permanent side effects that involve tendons, nerves, muscles, joints and CNS (“brain fog,” tinnitus, fatigue, poor concentration). Don’t forget that FQs are QTc prolonging and put patients at risk for Clostridium difficile infection (CDI).
  11. After I&D of an abscess, antibiotics had better cure rates and fewer recurrences than placebo. However,  while the results were statistically significant, the difference was small.  
    1. Dr. Sax feels more strongly about antibiotics after I&D if an abscess is on face, near genitals, or patient shows signs of systemically illness.
  12. Distinguishing antibiotic-associated diarrhea vs. Clostridium difficile (CDI):  Consider CDI when patient has associated abdominal cramping, fever, leukocytosis or hx of CDI.
  13. Note! Doxycycline has been shown to have potential protective effects against the development of CDI.
  14. Hierarchy of abx causing CDI: Clindamycin, FQ > extended spectrum beta lactams, > macrolides, TMP-SMX, penicillins > Doxycycline. See this article on hierarchy of antibiotics that cause CDI (Pharmacy Times by Sean Kane PharmD).
  15. Regardless of the reported hx of having chickenpox, you can presume anyone born before 1988 is immune to chickenpox and at risk for shingles.
  16. Recurrent zoster: rarely occurs, but the zoster vaccine is still recommended for people who have had shingles. A small portions of patients with a history of shingles are at risk for another episode, likely because the first shingles did not sufficiently boost their antibody responses, or due to immunosuppression. -Dr Sax

Goal: Listeners will feel empowered to tackle various common infectious disease related topic that come up in primary care.

Learning objectives:
After listening to this episode listeners will…

  1. Understand the current state with this year’s flu strain and flu vaccine
  2. Better equipped to educate patients on myths surrounding the flu vaccine
  3. Have better approach for immunizations or travel prophylaxis prior to traveling developing countries, especially for people from those countries
  4. Interpret of lyme serologies in the context of prior exposure
  5. Explore reported history of penicillin allergies and its correlation to true allergies
  6. Analyze antibiotic use after adequate abscess drainage
  7. Examine cost effective workup of diarrhea in the context of antibiotics and recent travel
  8. Explain the importance of shingles vaccination despite having had shingles or in the context of reportedly never having chicken pox
  9. Explore stewardship in using fluoroquinolones and their side effects

Disclosures: Dr Sax reports no relevant financial disclosures to this program. The Curbsiders report not relevant financial disclosures.

Time Stamps:

  • 00:00 Announcement
  • 01:38 Intro
  • 03:46 Picks of the Week
  • 06:47 Guest bio
  • 08:47 Getting to know our guest
  • 15:40 Flu vaccination
  • 19:54 Barriers to the flu vaccine
  • 23:34 Can you give the flu vaccine to an ill patient
  • 24:14 Man flu
  • 26:27 Travel Medicine
  • 30:35 Tick bites
  • 33:49 Lyme serologies
  • 35:38 Lyme prophylaxis
  • 37:37 Chronic lyme disease and post lyme syndrome
  • 38:55 Penicillin and antibiotic allergies
  • 41:48 Fluoroquinolones and adverse reactions
  • 45:24 Should antibiotics be given after an I&D of an abscess
  • 49:34 Antibiotic associated diarrhea, C diff
  • 52:10 Probiotics, stool transplantation, and C diff
  • 54:50 Shingles, recurrent zoster, complications, and the new subunit vaccine
  • 61:45 Using salad tongs at a buffet
  • 63:04 Take home points
  • 64:26 Outro

Picks of the Week:

  1. Core IM Podcast featuring Shreya Trivedi
  2. Vancomycin and Piperacillin Tazobactam combination may be nephrotoxic
  3. Paul recommends Clindamycin
  4. Shreya recommends Ceftriaxone
  5. Can We Talk About Something More Pleasant (book) by Roz Chast

Links from the show:

  1. Leon Sidari Memorial Fund
  2. The Curbsiders Cafe Press T-Shirt Page (all proceeds donated to the Leon Sidari Memorial Fund)
  3. Paules, Catharine I., et al. “Chasing Seasonal Influenza—The Need for a Universal Influenza Vaccine.” New England Journal of Medicine (2017).
  4. Arriola, Carmen Sofia, et al. “Influenza vaccination modifies disease severity among community-dwelling adults hospitalized with influenza.” Clinical Infectious Diseases (2017).
  5. The Science Behind Man Flu. BMJ. December 2017.
  6. “Malaria.” World Health Organization. Chapter 7.
  7. Feder Jr, Henry M., et al. “A critical appraisal of “chronic Lyme disease”.” New England Journal of Medicine 357.14 (2007): 1422-1430.
  8. Hung, Yuan-Pin, et al. “Doxycycline and tigecycline: two friendly drugs with a low association with Clostridium Difficile infection.” Antibiotics 4.2 (2015): 216-229.
  9. Kao, Dina, et al. “Effect of Oral Capsule–vs Colonoscopy-Delivered Fecal Microbiota Transplantation on Recurrent Clostridium difficile Infection: A Randomized Clinical Trial.” Jama318.20 (2017): 1985-1993.
  10. Sax, P. E. “HIV and ID Observations.” (2017).
  11. Daum, Robert S., et al. “Clindamycin versus trimethoprim-sulfamethoxazole versus placebo for uncomplicated skin and soft tissue abscesses.” Open Forum Infectious Diseases. Vol. 3. No. suppl_1. Oxford University Press, 2016.
  12. CDC Key Facts About Seasonal Flu Vaccine
  13. CDC Flu Vaccine and People with Egg Allergy
  14. CDC Travelers’ Health
  15. Lyme Disease from DynaMed Plus
  16. Feder, HM et al. A Critical Appraisal of “Chronic Lyme Disease”. N Engl J Med 2007; 357:1422-1430 (Free)
  17. Penicillin Allergy from Dynamed Plus
  18. Probiotics to Prevent Antibiotic Associated Diarrhea from DynaMed Plus
  19. FDA Warning on Fluoroquinolones

MCQ Answers: C, B, B


  1. January 17, 2018, 3:54pm Daria Chacon writes:

    Hey guys, this is great! I appreciate your podcasts. I'm a Med-Peds doc doing outpatient adult & peds care and inpatient IM rounding, have practice admin responsibilities in a busy inner-city practice, and am a mother of two preteens who believe the world revolves around them (to date I have been unable to convince them that astrophysics argues fairly convincingly against this). I've been binge-listening to them like some people binge-watch Netflix series. I do it on 1 1/2 speed because I'm busy, I'm impatient, and I enjoyed the Chipmunks' series as a child. As a result you all sound highly anxious. Love Dr. Toph's podcasts in particular; he almost makes the nephron make sense (emphasis on the "almost"). I have recommended your podcasts to all my colleagues at our health center. Add that to the long list of things that could conceivably get me fired.

CME Partner


The Curbsiders are partnering with VCU Health Continuing Education to offer FREE continuing education credits for physicians and other healthcare professionals. Visit and search for this episode to claim credit.

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