In this episode I’ll:
1. Discuss an article about prolonged empiric antibiotic therapy in adult ICUs
2. Answer a drug information question about eosinophilic nephritis
3. Share a 4T score calculator
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Lead Author: Zachariah Thomas
Published in Critical Care Medicine December 2015
Antibiotics decrease morbidity, mortality, and healthcare costs when given to treat infection; but they increase morbidity, mortality, and healthcare costs when given in the absence of infection.
The purpose of this study was to determine the rate of prolonged empiric antibiotic therapy in adult ICUs in the United States. The secondary objective was to examine the relationship between the prolonged empiric antibiotic therapy rate and certain ICU characteristics.
Multicenter, prospective, observational, 72-hour snapshot study in 67 ICUs from 32 hospitals in the United States.
Prolonged empiric antibiotic therapy was defined as empiric antibiotics that continued for at least 72 hours in the absence of adjudicated infection. The prolonged empiric antibiotic therapy rate was determined as the ratio of the total number of empiric antibiotics continued for at least 72 hours divided by the total number of empiric antibiotics.
A total of 660 unique antibiotics were prescribed as empiric therapy to 364 patients. Of the empiric antibiotics, 333 of 660 (50%) were continued for at least 72 hours in instances where Centers for Disease Control infection criteria were not met. Suspected pneumonia accounted for approximately 60% of empiric antibiotic use.
The most frequently prescribed empiric antibiotics were vancomycin and piperacillin-tazobactam. ICUs that utilized invasive techniques for the diagnosis of ventilator-associated pneumonia had lower rates of prolonged empiric antibiotic therapy than those that did not, 45.1% versus 59.5% (p = 0.03). No other institutional factors were significantly associated with prolonged empiric antibiotic therapy rate.
The authors concluded that 50% of all empiric antibiotics ordered in critically ill patients were continued for at least 72 hours in absence of adjudicated infection.
50% seems like an alarmingly high rate. When does empiric antibiotic therapy become inappropriate? Determining this is especially challenging in the sickest patients who have not yet responded to any therapies. Do they need a bit more time or should antibiotics be discontinued?
I am very interested in performing an analysis similar to this study of patients in my ICU. I’ll give a pre-emptive shout-out to Pharmacy Student Allison & Pharmacy Resident John who will be helping me figure this out!
Drug information question
Q: If my patient developed nephritis and eosinophilia from meropenem, can I switch them to piperacillin-tazobactam?
A: I’d avoid it if you can.
An 81 y/o female with a left knee implant infection due to enterobacter aerogenes developed eosinophilic nephritis after treatment with meropenem. This particular bug had a challenging resistance pattern:
SPECIMEN SOURCE: TISSUE LEFT KNEE
ORGANISM: RARE ENTEROBACTER AEROGENES
METHOD: BREAKPOINT SENS
AMPICILLIN: RESISTANT *R *
CEFAZOLIN(ANCEF): RESISTANT *R *
CEFTRIAXONE(ROCEPH): RESISTANT *R *
CIPROFLOXACIN: RESISTANT *R *
GENTAMICIN: SENSITIVE *S *
TMP/SXT: SENSITIVE *S *
AMPICILLIN/SULBACTAM: RESISTANT *R *
LEVOFLOXACIN: RESISTANT *R *
MEROPENEM: SENSITIVE *S *
CEFUROXIME(ORAL)AXETIL: RESISTANT *R *
PIPERCILLIN/TAZOBACTAM: INTERMEDIATE *I *
AMOX/CLAVULINIC ACID: RESISTANT *R *
TETRACYCLINE: SENSITIVE *S *
The ID physician was contemplating using piperacillin-tazobactam despite the “intermediate” resistance profile.
Eosinophilic nephritis from beta-lactam antibiotics is IgG mediated, and the possibility of cross-reactivity exists. I was able to locate a case report of a patient who developed nephritis from piperacillin-tazobactam and appeared to have a cross-sensivitity reaction to meropenem.
Given that information we decided not to use piperacillin-tazobactam. That left gentamicin, sulfamethoxazole-trimethoprim, and tetracyclines. Given the nephrotoxicity risk from gentamicin and sulfamethoxazole-trimethoprim, the ID physician elected to use tigecycline. As much as I typically avoid using tigecycline, this seemed like the best choice for this particular patient.
In episode 35, I shared with you a resource for evaluating drug-induced thrombocytopenia. To complement that resource I made a calculator for determining the “4T score”. The 4T score is a way to calculate the pretest probability that a patient has heparin induced thrombocytopenia. You can find this and other calculators at pharmacyjoe.com/calculators. If you would like to learn more about pretest probability, and the sensitivity and specificity of tests, listen to episode 23.
The Pharmacy Nation Slack group is a free group with other pharmacists from around the world collaborating with each other using real-time messaging to help better care for patients. Over the past week we’ve been talking about things like whether vasopressin should stay in code carts, clearing jejunostomy tubes, and hydrocortisone infusion vs intermittent dosing in septic shock. I invite you to join me and the 100+ other Pharmacy Nation members there. You can sign up at pharmacynation.org.
I’m putting together a course on how to start a medical podcast – so that other medical professionals can bring their knowledge, expertise, and voice to the world of podcasting. To learn more about the course, and to sign up to be notified when it is available, head over to howtostartamedicalpodcast.com
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.