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Isolation and culture of anaerobic bacteria have become routine procedures in clinical microbiology laboratories, but it is still essential to use strict culture conditions and appropriate media if accurate results are to be assured. Laboratory staff play a vital role in steering the diagnostic process and must communicate effectively with clinicians to reach the correct conclusion.
Maximising the recovery of bacteria from a clinical sample is a process that begins before the sample reaches the laboratory. This is especially true for anaerobes and other fastidious bacteria.
Optimising the isolation and identification of anaerobic bacteria associated with infection can facilitate the selection of appropriate antibiotic therapy. Recent improvements in methods for isolating anaerobes from clinical specimens have been driven by factors including, an increase in immunocompromised patients, changes in the antibiotic resistance of anaerobes and more virulent anaerobic species.
This process of isolating anaerobes from a sample can be broken down into three stages: sample collection, processing, and incubation.
Collection:
Collection and preservation of specimens suitable for anaerobic bacteriology is something that Don Whitley Scientific has thoroughly investigated, in collaboration with the UK Anaerobe Reference Unit and within the processes used in DWS’s onsite laboratory.
Published research emphasises the importance of appropriate and consistent practices in the collection and transportation of specimens. Choosing the correct method for specimen transportation is paramount in minimising the risk of damage to the sample, as oxygen exposure will quickly reduce the viability of the more fastidious anaerobes.
Recognising this fact, Don Whitley Scientific is the UK distributor for Copan Liquid Based Microbiology products. The eSwab collection combines a swab and transport medium in a compact and automation-compatible design. In particular, the liquid Amies eSwab allows for even sample distribution upon plating due to the construction of the swab. The material collected by the swab is eluted into the Amies solution, allowing the sample to be taken directly from the liquid. The combination of the swab and the Amies solution helps increase the viability of organisms in the sample.
Processing:
As eSwabs are compatible with automated swab processing systems, they provide an opportunity to reduce the risk of human error and contamination, while also minimising the time between collection and incubation – important in maximising the isolation of anaerobes. Whether processed manually or with the aid of automation, eSwabs can also be used in conjunction with Whitley Anaerobic Workstations to provide strict anaerobic conditions for sample processing and incubation.
Incubation:
It is important to place inoculated culture media into anaerobic conditions within 15-20 minutes. Only the most ‘moderate’ anaerobes will survive prolonged exposure to air, so it is vital to adapt laboratory procedures so that this stage of the process is properly controlled.
Don Whitley Scientific’s range of anaerobic workstations and anaerobic jars, in conjunction with the Whitley Jar Gassing System, can be used to provide the required incubation conditions. The Whitley Anaerobic Workstation range provides exceptional control of oxygen levels, temperature and humidity.
Correct procedures are crucial when collecting, processing, and incubating samples for the isolation of anaerobes. If you are interested in exploring any of the topics discussed in this article, please contact Don Whitley Scientific. Contact details can be found below or get in touch through the chat support on our website.
Email: sales@dwscientific.co.uk
Telephone: +44 (0)1274 595728
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