In this article two infectious diseases pharmacists interview a veterinarian about his perspective on antimicrobial stewardship.
Interviewee: Ian DeStefano, DVM
[Last updated: 18 February 2020]
Antibiotic use and subsequent antibiotic resistance get a lot of attention in humans, but what about in animals? Animals get infections too, and unfortunately even our furry friends can succumb to antibiotic-resistant infections. Additionally, antibiotic use in agriculture (particularly for animal growth-promotion) accounts for 80% of all antibiotic use in the United States. In fact, resistant bacteria can spread between animals and people through food or contact.
The recent 2019 Antibiotic Resistance Threats Report from the CDC emphasizes the importance of antibiotic stewardship in humans and animals with a focus on “One Health”—a collaborative, multisectoral, and trans-disciplinary approach to optimize health outcomes by recognizing the interconnectedness of humans, animals, and the environment.
We met Ian DeStefano via Instagram and *instantly* connected. Dr. DeStefano is in his third and final year of veterinarian residency, specializing in emergency and critical care where he mostly manages patients (and here, patients refer to animals) requiring mechanical ventilation or who are hospitalized with sepsis, severe trauma, or other complex or life-threatening multisystemic diseases. His interest in infectious diseases and antimicrobial stewardship stemmed from carrying for patients with sepsis and his husband, who is a BCIDP pharmacist!
Ian was kind enough to share some considerations for antibiotic use and stewardship in his patient population, as well as his interests and goals for the future.
1. Can you tell us a little more about what piqued your interest in infectious diseases and antimicrobial stewardship, and some of your first initiatives?
My interest in infectious diseases (ID) started primarily as an intern while starting out managing critical septic patients, most frequently septic pneumonia and septic peritonitis (usually a GI perforation in a dog/cat). As a sidetone, my husband is a pharmacist as well (now BCPS/BCIDP), and I think just coming home and talking about my cases/my work day and our discussions these are what really sparked my interest in antimicrobials, especially “appropriate” use of antimicrobials. I took that interest/background with me going into residency.
My first publication/ project was a retrospective review of vancomycin at our hospital. For reference, vanco is hardly used in veterinary medicine (vet med), and I think with good reason as I am not convinced that we really know what we are doing with the drug. I already knew a bit about vancomycin due to my standard (albeit nerdy) dinnertime conversations, but then I was transferred a case while on ICU of a dog with urosepsis who had a documented MRSA UTI go untreated. The isolate’s susceptibility for that infection showed the only options were sulfamethoxazole/trimethoprim, chloramphenicol, or amikacin. The dog was mildly azotemic, and the admitting team did not think the dog could tolerate oral medications (chloramphenicol is used in tablet form in veterinary medicine), so he was started on vancomycin. While I think that was an appropriate initial choice, I suddenly was left to scramble to see what we knew about the drug and its use in dogs. As it turns out, the literature consisted basically of a pharmacokinetic/ pharmacodynamic study in healthy beagle dogs and a few single case reports of its use in 1-2 dogs and 1 cat. In addition, therapeutic drug monitoring for most drugs that we use is either non-existent or not clinically useful (vancomycin for example can be run at one or two academic hospitals in the US, and the turn-around time limits its use clinically).
In my review, I noted that vancomycin had been used empirically in the vast majority of cases, and based off what I could tell retrospectively through grueling chart review, it really did not seem indicated approximately 95% of the time.
The article is available here…
- DeStefano IM, et al. Parenterally administered vancomycin in 29 dogs and 7 cats (2003‐2017). Journal of Veterinary Internal Medicine. 2019; 33(1): 200-2017.
2. It’s interesting to hear animals and humans have the same struggles—we overuse and struggle to perform appropriate TDM with vancomycin, too! Outside of vancomycin, what antibiotics do you most commonly give to your patients? For what indications?
There’s such a variety! It really depends on the disease process, I suppose. Based on culture results spanning back about 10 years at our own hospital, we cover septic peritonitis with ampicillin/ sulbactam and Baytril (enrofloxacin, a veterinary fluoroquinolone) in the patient with no antimicrobial history. Secondary peritonitis I tend to reach for cephalosporins (ceftriaxone, occasionally ceftazidime) +/- metronidazole. We have some preliminary but compelling evidence that dogs with pneumonia (usually aspiration) even when teetering with sepsis typically only really need ampicillin or ampicillin-sulbactam, though obviously exceptions occur.
I would say that spanning all types of infections, probably the most frequently prescribed for cats and dogs on an inpatient basis tend to be ampicillin, ampicillin/sulbactam, enrofloxacin, metronidazole, and clindamycin. I do not always agree with how they are used, but those are the most common. Less common but not “unheard of” examples would be ceftriaxone, ceftazidime, and occasionally meropenem. We are trying to implement restriction of carbapenems in our hospital without consultation or fulfilling checklist criteria. Common outpatient/ oral meds not listed above include sulfamethoxazole/ trimethoprim, cephalexin, cefpodoxime, marbofloxacin or pradofloxacin (other veterinary fluoroquinolones).
3. You told us you sit on your hospital’s newly founded Infection Control and Antimicrobial Stewardship Team. What are your target initiatives or goals for the next 2 years?
Our team (ICAST for short) has many goals in the next few years – perhaps too many!
Right now what we are really working on from an antibiotic use standpoint are guidelines for specific disease syndromes for empiric use while pending culture results (which often take 3-5 full days to finalize for us!) to serve as a resource for house officers as well as boarded specialists in the hospital. Being a “new” group, our goal currently is to organize and establish a baseline. This isn’t meant to be a regulatory group – at least not in the near future.
Some of the ideas we are trying to address include the rampant use of metronidazole and post-surgical prophylactic use of cefazolin. For reference, there is this “old wives’ tale” in vet med about metronidazole being “an anti-inflammatory” to the gut. I still am not sure where it came from, as the few times I have really tried to sit down and get to the bottom of it, the only compelling evidence I have found is in a rodent model of rosacea. Regardless, it is extremely common practice for veterinarians to blanketly prescribe metronidazole for acute diarrhea, when we have zero evidence for it. In fact, some new studies are showing that resolution of acute non-specific diarrheal disease in dogs to have faster resolution times with placebo!
There is also some dodgy evidence for continued use of cefazolin or cephalexin post-op for orthopedic procedures in dogs to prevent surgical site infections, which some have taken as far as continuing all post-op ortho cases on roughly two weeks of cephalexin!
So there is a lot in terms of education and “getting the word out” to do. Another common problem I face is the general misunderstanding of anti-anaerobic drugs and what bug-drug combinations are actually covered. For example, it’s not uncommon for me to hear “well the dog with cholangitis is on ampicillin-sulbactam or Baytril, but I am adding on metronidazole for better anaerobic coverage.” Usually that’s enough to peak a slight transient tachyarrhythmia in me (though I have gotten better at hiding the outward signs).
One of my current prospective research projects involves surveillance testing to attempt to discern the rates of catheter-associated urinary tract infection (CAUTI) vs. catheter-associated bacteriuria (CAB) in hospitalized dogs. While there are several studies of CAUTI in dogs of both specific and non-specific patient/disease groups, none differentiate positive urine culture from infection. So we are actively enrolling dogs for that now.
4. What are the most problematic drug-resistant pathogens you (or vets in general deal with)?
We face many multi-drug resistant (MDR) organisms, but I would have to say some common top contenders would be extended-spectrum beta-lactamase (ESBL) producing E. coli or other Enterobacteriaceae, and methicillin-resistant Staphylococcus pseudintermedius (MRSP).
MRSP causes a huge problem in the dermatology world, but I have had that cross over into the types of patients I treat – I once diagnosed a dog with bacterial meningitis (MRSP) on an overnight. The dog had congenital hydrocephalus and had a ventriculoperitoneal drain device placed by neuro maybe 5-6 months earlier but it had recently stopped draining. The owners were undecided about replacing it so it had just been intermittently drained percutaneously though a port… it turns out the port must have been contaminated because when I went to sample in a closed system the entire syringe filled with pus without even aspirating.
Another case I can think of that I treated was a cat who had bilateral ureteral stone obstructions and was thus anuric who went to emergency surgery for bilateral subcutaneous ureteral bypass devices who had a prolonged recovery from anesthesia and ultimately died of aspiration pneumonia which we had cultured – MDR E. coli sensitive only to carbapenems and amikacin. So, I get teased a lot about being obsessed with proper and appropriate use of antibiotics at work, but those are the end results that only the ICU team tends to see that drive it home.
5. You deal with really complex patients, but can you share with our readers the biggest concerns/considerations for antibiotic use and antimicrobial stewardship in household pets? Cats and dogs in particular?
I actually think I have far fewer concerns about stewardship from the pet owners’ standpoint. What I mean by that is that at least in the USA, there really are not OTC options for antibiotics for owners to obtain and/or use – the only exception is feed stores, but that is primarily a food animal problem. I do think that antibiotics are very likely overprescribed still by the practitioner. There was actually a recent veterinary study about this (available here: Pet owners’ knowledge of and attitudes toward the judicious use of antimicrobials for companion animals).
What I think a lot of veterinary professionals struggle with is lack of consistent and appropriate diagnostic testing as it relates to infectious disease (or otherwise). As most pet owners do not have insurance for their pet (though that does seem to be becoming more common), the cost of care and an owner’s resources unfortunately affect practice all the time. Let me give you a fictional example: an adult cat is brought to you with the classic cat history (“ain’t doin’ right” – anorexia, quiet, less active). Physical exam is normal. The differential list is virtually anything! You recommend some baseline diagnostics (CBC, chemistry, UA). Even in the setting where you have results back that day, let’s say everything’s normal. You know what to recommend next (abdominal ultrasound, chest radiographs, etc.) but the owner cannot afford it right now. “You just spent my leftover money this month on those other tests, doc!” That’s a very common scenario where a new veterinarian may be tempted to just treat “symptomatically” with an antiemetic, maybe some Clavamox (doggie Augmentin, amoxicillin/ clavulanic acid) as well. The owner is counseled. Recheck 1 week later – the kitty is back to normal. Did we treat an infection? Did the cat just need an antiemetic? Are cats just aliens and would all have been fine regardless? Well we do not always know in that situation, but it sometimes reaffirms a bad habit for veterinary professionals. However, I think we tend to see (on a referral basis) both unjustified or indiscriminate antibiotic use as well as documented notes of why an antibiotic is not being prescribed, so this practice isn’t uniform.
I know from an informal standpoint as well as sifting through lots of veterinarian social media groups that there are lots of people who practice good stewardship, perhaps more than I used to run into. Still, we have a LOT to do!
6. To end on a fun note, what is your favorite thing about veterinary medicine?
This may sound silly, but I love that I can pet my patients and talk to them in a high-pitched voice and spoil them with cold cuts and have it be completely socially acceptable (probably encouraged really). Those “silly” things help balance out the other things that can be frustrating/depressing. I might be able to verbally recite to you your dog’s ventilator settings and details of their mixed acid-base disturbance, but you can bet your bottom dollar my goal is to wake them up so we can cuddle and I can feed them treats and then discharge them home!
Check out resources from the American Veterinary Medical Association on antimicrobial use in veterinary practice, including this awesome stewardship checklist, antimicrobial do’s and don’ts for cats and dogs, and a report from the AVMA Task Force on Antimicrobial Stewardship in Companion Animal Practice to provide guidance for implementing antimicrobial stewardship.
We would like to express our utmost gratitude to Dr. DeStefano for taking the time to complete this interview and share his insights and opinions.
ABOUT THE INTERVIEWEE
Disclosures: The views expressed in this interview represent that of the individuals only and do not necessarily reflect the position or policy of their previous, current, or potential future employers or other organizations in which they serve.
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