Canadian Vet Tech uses the same unique format as Canadian Vet newsmagazine to keep veterinary technicians and animal health technologists informed through coverage of both national and international conferences. Initiated in March 2009, each quarterly issue offers up-to-date information on animal health and client management, animal behaviour, and veterinary communications topics. The Technically Speaking column, written by Kathleen Dunbar, RVT, challenges vet techs on a variety of important and interesting clinical scenarios. Each issue also features a ‘Day in the Life of’ essay, written by a vet tech about their experiences in this career. All articles in Canadian Vet Tech are reviewed and approved prior to publication.

Continuing Education

Every issue of Canadian Vet Tech includes 3 articles with associated CE quizzes that can be completed online, at www.k2publishing.ca, to earn CE credits. Vet techs can complete a total of 12 quizzes each year to earn CE credits. Both current issue quizzes, and quizzes from prior issues, will be available for completion online. Canadian Vet Tech CE quizzes are approved for credit by all of the provincial accrediting associations in Canada.

Technically Speaking, by Kathleen Dunbar, RVT, VTS (Clinical Practice-Canine/Feline)

In each issue of Canadian Vet Tech we run an outstanding column by registered veterinary technician Kathleen Dunbar that offers vet techs an opportunity to really challenge themselves. Each article consists of 10 multiple choice questions. You can take the quiz online under our CE quizzes menu and then go to www.k2publishing.ca/technicallyspeaking.html to read an explanation of the answers.

Antibiotic pearls for the veterinary technician

By Dennis Spann, DVM, DACVIM

The discovery and development of antibiotics was an essential prerequisite to much of what we consider advanced modern medicine. Without antibiotics, mortality rates following trauma, surgery, and chemotherapy would be much higher. Many of the advanced interventional and supportive techniques that we now nearly take
 for granted would be impossible. However, bacteria have intrinsic mechanisms to protect themselves from antibiotics, so the possibility developing resistance is possible any time antibiotics are used. Sir Alexander Fleming warned of antibiotic resistance through careless or excessive antibiotic use even as penicillin was entering into widespread use in the late 1940s. By the 1960s extensive penicillin resistance had occurred. The same scenario occurred with other antibiotics. In addition to antibiotic resistance there has been a significant slow down in the production of new antibiotics.  The time to profitability of new antibiotics can be 20 years, and even then they are not as profitable as other “blockbuster” medications that may require daily administration over years or decades.  The net effect is that we have fewer tools to combat infection.

The development of resistance


Bacteria populations develop resistance by a number of mechanisms. Most important are spontaneous mutations, and acquisition of genetic material that contains resistance genes. This genetic material can be obtained through conjugation, transfection from viruses, and transformation from the environment.  Since many antibiotics are natural biological compounds or chemical derivatives of those compounds, bacteria developed mechanisms to acquire resistance long before we applied antibiotic selection. Indeed microbes have used antibiotics as defence and resistance for millions of years.  Some bacteria, such as Pseudomonas spp. Acinetobacter spp., and others, are naturally resistant to multiple antimicrobials, while many of the enterics (E.coli, Klebsiella and others), rapidly acquire resistance.  Recently, a Paenibacillus sp.  isolated from a cave that has been undisturbed for 4 million years was found to be resistant to the recently developed antibiotic daptomycin.  By carefully limiting antibiotic residues in the environment, we can help decrease the selection for resistance.

Can the veterinary profession make a difference?

With increased resistance and fewer new antibiotics in the pipeline, we must, as a profession, better utilize available tools. Since veterinary nurses are non-prescribers, the question often asked is: “Can we make a difference?” The answer is a profound:  “Yes!” There are several keys to better antibiotic utilization and these include: prevention of infection, antibiotic selection, optimized antibiotic usage, and education of clients and staff.  Because nursing staff operate directly with the patients and are at the intersection of patient, doctor, client and staff, they might be best suited to affect optimal antibiotic usage.

The first steps to protecting our patients

The first step to best utilization of antibiotics is to minimize their usage by preventing infection.  This includes identifying “at-risk” patients. These would include trauma patients, surgical patients, very young and old patients, and immune suppressed patients. Infection prevention includes preventing bacteria from growing and thriving in organic matter and biofilms. As medical professionals, we have the potential to spread diseases to our patients. Thorough hand washing before and after every contact with patients or biologics (blood, urine, saliva, discharges) is a simple step that profoundly decreases the transfer of bacteria to our patients. Scrubs or short sleeve shirts, bare to the elbow, decrease our participation in bacterial spread as fomites.  Cleaning the environment with bleach and accelerated peroxides effectively destroys many pathogens. Peroxides have the advantage of causing less pitting and surface wear which often interfere with thorough cleaning.

Antibiotic preservation involves multiple components:

  1. Judicious use of remaining antibiotics and prevention of resistance depends on antibiotic stewardship
  2. Preventing infections 
  3.  Best use of antibiotics
  4. Monitoring response to therapy
  5. Team effort – doctors, nursing staff, clients, infectious disease experts
  6. Education of professionals and clients

Which antibiotic should I choose?

Antibiotics should be chosen based on culture, but initial choices are often empirical and based on knowledge of likely pathogens and their sensitivities for each body system. Nursing staff can educate themselves, and learn from clinicians, about organisms and best antibiotics for the affected body system. A re-evaluation of culture results and effectiveness of an antibiotic can be incorporated into the flow sheets for each in-patient, as well as a running count of days on antibiotics. The nursing staff should be encouraged to ask clinicians about the expected length of therapy for the antibiotic. 

Understanding  antibiotic families

Antibiotics are grouped by various categories. Important groupings include chemical families derived from a core molecule. An example would be the penicillins.  Each family tends to share a mechanism of action. But different families may also share similar mechanisms, such as the penicillins and the cephalosporins, which are both cell wall inhibitors. Or the aminoglycosides and the macrolides, which are both  protein synthesis inhibitors. Antibiotics are further characterized as time-dependent, where increased time above the minimal inhibitory concentration (typically 2-4 times the minimum inhibitory concentration (MIC)) tends to optimize bacterial killing (penicillin, cephalosporins, clindamycin). These antibiotics often have little post antibiotic effect. The other important class are the concentration-dependent antibiotics (aminoglycosides and fluoroquinolones) in which peak concentration (typically 10 times the MIC) and area under the concentration curve (AUC) are the most important determinants of bacterial killing.  Dosing these antibiotics is best done by achieving either longer time (>50 % of the dosing interval) above MIC, or a higher ratio of peak concentration to MIC. Failure to appreciate these characteristics may create a selection advantage for resistant clones. The time-dependence of some antibiotics has led to the practice of transforming antibiotic infusion into a continuous infusion to keep antibiotic concentration continuously above the MIC. While this makes conceptual logical sense it has only been shown to be advantageous in the setting of severe sepsis.

Knowledge of likely bacteria and their typical sensitivity is essential for good antibiotic choice, while waiting for culture results to return. Recent technology like mass spectroscopy (MALDI) has decreased the time until culture results are available. Across the blood-brain barrier, antibiotic choices might include fluoroquinolones, metronidazole, chloramphenicol, and TMS at high concentration. With inflamed meninges, cephalosporins, aminoglycosides, and betalactams become reasonable choices.

Many antibiotics are excreted in the urine.  Penicillin and first generation cephalosporins are generally good choices for uncomplicated urinary tract infections. For hepatic and biliary infections, amoxicillin clavulonate, unasyn sulbactam, clindamycin, select fluoroquinolones, and first generation cephalosporins should be useful.       

Once chosen empirically, the selection should be refined in 48-72 hours, based on culture results and clinical response. Antibiotics should be narrowed to monotherapy when one can be confident about culture results.

Consider the risks

Antibiotics are not without risk. In human medicine, reactions to antibiotics are a leading cause of emergency room visits. Well-documented reactions, like skin eruptions, blood dyscrasias, KCS, arthritis, connective tissue complications, renal and hepatic failure, and others occur in veterinary and human medicine.  Clients are increasingly aware of bacterial resistance issues and often understand the “One Health” imperative of combating resistance. With proper education, they are more likely to support appropriate diagnostics. Using fewer antibiotics has been proven to decrease resistance in several studies. We must commit ourselves to be part of the solution, not part of the problem.CVT