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In this Part 2 of EM Cases' Highlights from Whistler's Update in EM Conference 2015 Dr. David Carr gives you his top 5 pearls and pitfalls on ED antibiotic use including when patients with sinusitis really require antibiotics, when oral antibiotics can replace IV antibiotics, how we should be dosing Vancomycin in the ED, the newest antibiotic regimens for gonorrhea and the mortality benefit associated with antibiotic use in patients with upper GI bleeds. Dr. Chris Hicks gives you his take on immediate PCI in post-cardiac arrest patients with a presumed cardiac cause and The Modified HEART Score to safely discharge patients with low risk chest pain.

Written summary & blog postPrepared by Dr. Keerat Grewal & Dr. Anton Helman, May 2015
5 Antibiotic Pearls and Pitfalls
1. Sinusitis & Pharyngitis rarely require antibiotics
How to identify acute bacterial vs viral sinusitis

From IDSA Guidelines (2012)

1 of 3 presentations make bacterial sinusitis more likely:

* Onset with persistent symptoms or signs compatible with acute rhinosinusitis with symptoms lasting 10 or more days, without any evidence of improvement
* Onset with severe symptoms or signs of high fever (>39.0 C), purulent nasal discharge, or facial pain lasting at least 3-4 consecutive days at the beginning of illness
* Onset with worsening symptoms or signs characterized by the new onset of fever, headache or increase in nasal discharge following a typical URI that lasted 5-6 days that were initially improving (i.e. the “Double Sickening”)

Dr. Carr recommends treating sinusitis with antibiotics only in immunocompromised patients, post-op patients and septic patients, as most are viral and the NNT to shorten the duration of illness is 13.
McIassac Pharyngitis Score
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Dr. Carr’s Commentary: Antibiotics are rarely (if ever) required for pharyngitis in adults as most cases are viral, only approximately 50% of patients with a McIssac score of 4 or 5 have strep throat, rheumatic fever in adults is extremely rare in North America (with little evidence that antibiotics prevent it), and the NNT to prevent suppurative complications of strep throat is approximately 400.

Oral Penicillin for Pharyngitis: Number Needed to Harm

NNH = 5000 for anaphylaxis

NNH = 10 for diarrhea

*Note that there are still cases of pediatric rheumatic fever in Canada, and so withholding antibiotics for children with strep throat is not recommended at present.

 
2. Consider the bioavailability of oral antibiotics before you pull the trigger and give IV antibiotics
High Bioavailability oral antibiotics to consider instead of IV antibiotics:

Cephalexin

Quinolones – eg. ciprofloxacin, levofloxacin

Trimethoprim-Sulphamazoxazole – eg. Septra, bactrim

Clindamycin

Metronidazole

Doxycycline

Linezolid
3. Approriate Vancomycin Dosing
Use weight-based dosing of vancomycin (20-30 mg/kg based on severity of illness) rather than simply 1g or 2g. This will prevent the historical under-dosing vancomycin.

 
4. New Antibiotic choices for Gonorrhea
From 2014 Toronto Public Health

Uncomplicated gonorrhea: azithromycin + ceftriaxone regardless of whether the patient is positive for chlamydia.

PID: ceftriaxone + doxy +/- azithromycin 2g qweekly x2

Consider single dose gentamycin or gemifloxacin + azithromycin in high risk populations (i.e. men who have sex with men)

See The Skeptics Guide to EM (http://thesgem.com/2015/01/sgem104-lets-talk-about-sex-baby-lets-talk-about-stds/) for analysis of this study

 
5. Antibiotics for Upper GI Bleeds in cirrhotic patients
A Cochrane review meta-analysis in 2011 showed an all-cause mortality benefit in using prophylactic antibiotics in cirrhotic patients with upper GI bleeds.