By Anette Loeffler, Associate Professor of Veterinary Dermatology, and Siân-Marie Frosini, Lecturer in Veterinary Clinical Microbiology

Rapidly spreading viruses, such as those responsible for the current COVID-19 pandemic or the 2001 foot-and-mouth outbreak in the UK, have dominated the headlines on infectious threats in recent decades. However, bacteria, and multidrug-resistant strains in particular, remain amongst the most important challenges to human and animal health. 

In fact, secondary bacterial pneumonia is now recognised as the major cause of deaths during the 1918–1919 influenza pandemic and seen as a dangerous complication for COVID-19 patients.

Antimicrobial resistance is also recognised as a growing problem in veterinary medicine, particularly for animals undergoing intensive care treatment, surgery, or treatment for chronic disease. It is therefore critical that microbial pathogens can be identified correctly and that their antimicrobial susceptibilities are available to clinicians quickly so that appropriate treatment can be given.

To address these needs, the RVC Diagnostic Microbiology Lab, based at our Hawkshead Campus, has been updated and will fully re-open by May 2021 with exciting new machinery and a new team, ready to provide a state-of-the-art service to clinicians.

Clinical samples will be analysed by a team of experienced veterinary microbiologists, who will be able to make use of MALDI-TOF (matrix-assisted laser desorption/ionisation-time of flight, VITEK-MS, bioMérieux) technology for rapid identification of pathogens and an automated microbroth dilution system (Vitek2, bioMérieux) to test for antimicrobial susceptibility.

MALDI-TOF machines determine bacterial (or fungal) “fingerprints” through mass spectrometry, comparing the spectra obtained to a database of >1,300 species that has already been expanded to include hundreds of veterinary pathogens. This allows assignment of genus and species of relevant pathogens with great accuracy, while automated microbroth dilution testing will improve previous laboratory reports by providing clinicians with additional minimum inhibitory concentrations (MICs) for the individual antimicrobials. This may greatly improve patient care by highlighting some treatment choices that would otherwise not have been obvious.

The need for accurate identification of bacteria and their antimicrobial-resistance profiles first became pressing 20 years ago when the multidrug-resistant human hospital pathogen MRSA (meticillin-resistant S. aureus) started to be recognised in companion animals – and substantially complicated treatment choices for infected pets.

The first case series of MRSA infections in dogs was reported by Jane Tomlin (RVC) and colleagues in 1999 in dogs suffering from skin or wound infections (Tomlin et al. 1999). Unsurprisingly, in parallel to developments in human medicine, many other multidrug-resistant bacterial pathogens have since been recognised in animals and require in-depth diagnostic testing.

Microbiology laboratories play key roles in the defence against multidrug-resistant pathogens. By detecting problem-pathogens early, laboratory testing helps to limit outbreaks of potentially zoonotic or contagious organisms and supports good patient treatment outcomes through accurate and tailored assessment of antimicrobial susceptibilities for clinicians. The two new machines in the RVC Diagnostic Microbiology Lab will substantially reduce reporting times so that diagnoses can be made and effective treatment implemented promptly.
In addition to the new technology, RVC clinicians from all disciplines will now be able to discuss microbiology reports of complex cases with our new clinical lead for the microbiology laboratory,

Dr Siân-Marie Frosini (RVC veterinary graduate 2013 and now Lecturer in Veterinary Clinical Microbiology). The team will monitor and analyse microbial culture results using specialist computer software and work closely with our Infection Control Team and a newly established Antimicrobial Stewardship Group at the Queen Mother Hospital for Animals to ensure antimicrobials are prescribed and used appropriately.

As before, the diagnostic microbiology service will be available to clinicians from all RVC animal hospitals and all other clients from external veterinary practices, hospitals and institutions for samples submitted via the usual route to the RVC Pathology & Diagnostic Laboratory Service.

Reference:

Tomlin J, Pead MJ, Lloyd DH, Howell S, Hartmann F, Jackson HA, Muir P. ‘Methicillin-resistant Staphylococcus aureus infections in 11 dogs’. Vet Rec. 1999;144:60-4.