A new era in bacterial detection for healthcare?

Dr Andrew Kemp PhD, principal scientific officer at Q Technologies group, University of Lincoln, believes Bacteria Specific Rapid Metabolic Assay (BSRMA) could take us a step closer to a new era in bacterial detection.

Culture media and techniques have remained almost unchanged in over 100 years and in 2018 the question has to be asked: “Is it fit for the purposes we are using it for?” The increasing availability of Polymerase Chain Reaction (PCR) and Next Generation Sequencing (NGS) to identify species has increased the speed in which we get a result, but it is still difficult to be accurate about numbers from all species.

There are tests available that count the total amount of Adenosine Tri Phosphate (ATP), however, there has yet to be found a correlation between total ATP and bacterial ATP, as such this type of test can be considered of no clinical value.[1,2]

Bacteria Specific Rapid Metabolic Assay (BSRMA) was developed as a battlefield test for biological weapons, and was only recently adapted for use outside the military environment. Results using this newly available test on surfaces, skin and in urine have been incredibly revealing.[1,3,4,5,6]

How does BSRMA work?

There are many recent studies regarding the efficacy of bacteriophage-related lytic enzymes (BPLE) or viruses that infect bacteria. By degrading the cell wall of the targeted bacteria, these lytic enzymes have been shown to efficiently lyse Gram-positive and Gram-negative bacteria. Recent studies have suggested approaches for lysing
Gram-negative bacteria as well.[7]

Bacteriophages are viruses that kill bacteria and are most commonly used at targeted bacterial species. They have not been shown to contribute to antimicrobial resistance, are safe for humans, animals, and the environment.

The current focus on BPLEs has been on their use as anti-infectives in humans and more recently in agricultural research models. The initial translational application of lytic enzymes, however, was not associated with treating or preventing a specific disease but rather as an extraction method to be incorporated in a rapid bacterial detection assay.[5,6,8]

When used in a BSRMA, a number of BPLEs are combined, to lyse the cell walls of all bacterial species. We can trace the translational history of BPLE’s from their initial discovery in 1986 for the rapid detection of group Streptococcus A in clinical specimens, to evolving applicationsin the detection and prevention of diseasein humans and in agriculture.[5]

The BSRMA three-stage test uses BPLE technology for the removal of all Somatic cells (all cells except bacteria) from the sample (stage 1), leaving only living bacteria in the sample ready be lysed for measuring the intracellular ATP (stage 2).
Luminescence is then added to the sample using the positive charge on the ATP within the cell to produce light (stage 3). A direct correlation between cell numbers and amount of light produced shows a statistically proven,[1 ]Relative Light Unit
(RLU) to 1 Colony Forming Unit (CFU).[5,6]

(See Graph 1)

Graph 1

Bacteria Specific Rapid Metabolic Assay (BSRMA) was developed as a battlefield test for biological weapons, and was only recently adapted for use outside the military environment.

Results using BSRMA

Immediately after the annual deep cleaning of an orthopaedic operating room, multiple samples comparing culture to BSRMA were taken.[2] Results from culture provided no growth in any of the samples at 48 hours, whereas, the BSRMA results showed approximately 588 million live bacteria were still present. (See Graph 2)

Graph 2

The test is new to healthcare, however, it’s proven track record in the military and the US food industry [5,6] demands our attention and discussion. With results in five minutes or under, we can now test clinically important surfaces in high risk areas and hand sanitation. (See Graph 3)

Graph 3

Importantly we can now also test urine, and CSF samples for immediate accurate bacterial numbers. In a recent pilot study, 100 urines samples were processed and tested using microscopy, blinded and then tested again using BRSMA. Two samples were unsuitable for microscopy, but were tested with BSRMA, showing significant bacterial presence of 103,212, and 949,631 CFUs per 50ul. Culture was not performed in 16 samples after microscopy, however, when tested with the BSRMA, showed between 21,688 and 949,943 CFU per 50ul. In 12 samples that went onto culture after microscopy there was no significant growth at Culture, however, BSRMA showed between 54,901 and 954,815 CFUs per 50ul.

Discussion

The role of surfaces in primary and cross contamination is not yet fully understood2 and, as such, the routine assessment of bacterial contamination on surfaces is not yet common practice in UK healthcare facilities. Cleaning and disinfection regimes are for the most part left unchallenged. Due to the speed and accuracy of this new test, this situation can be changed quickly. It has the potential to help identify both poor technique and poor product efficacy, which may lead to significant improvements in both. There is a saying in management circles: “If you can measure it, you can improve it,” [9] and this is also true for cleaning and disinfection practice.

In addition, the early identification of live bacteria in bodily fluids such as urine and CSF, may well be able to assist in early indication of an active bacterial infection or not, increasing the tests clinical relevance still further. Although the work in this area is unpublished to date, it has stimulated the request for grant funding to take this work onto a full study to identify UTIs early, perhaps even as early as at the local General Practice clinic.

There is also a proposal for a study into early diagnosis of children with symptoms indication a suspicion of meningitis. It is hoped the BSRMA will help to indicate if it is a bacterial or viral meningitis. Earlier diagnosis of this condition from a urine sample may help to save a significant number of lives, and/or limbs and save the patient from having to undergo a difficult and painful lumbar puncture.

An additional benefit when studying or simply testing efficacy of hand hygiene practice, it may be a fast, simple way of removing the Hawthorn effect from these studies as it does not allow time for staff to change their practices before sampling.[1]

References

1 Kemp A, Hodgkinson V, Bugg A. Alcohol gels: More harm than good? Clinical Services Journal Vol 17 (2) 44-46 Feb 2018
2 Kemp A, Diggle M, Laird K. Cleaning and Disinfection Quality. Guidance standards for establishing and assessing cleaning and disinfection in UK Hospitals and other healthcare facilities. July 2017. https://www.qtechnologiesgroup.com/wpcontent/ uploads/2018/06/Healthcare-Environmental-Cleaning-guide-and-standards.pdf
3 Kemp A, Hodgkinson V, Bugg A. Prevention is better than cure – Clinical Services Journal Vol 16 (9) 61-63 Oct 2017
4 Kemp A, Hodgkinson V, Bugg A. Alcohol gels, the end of an era? Clinical Services Journal Vol 17 (6) 52-54 Jun 18.
5 GR Siragusa, CN Cutter. Microbial bioluminescence as a means to detect contamination on artificially contaminated beef carcass tissue. Journal of food protection Vol 58 No(7) 764-769 1995
6 CN Cutter, WJ Dorsa, GR Siagusa. A rapid microbial bioluminescence assay for meat carcasses. Dairy, food and environmental sanitation Vol 16, No(11), 726-736 1996
7 Phage therapy: Past, Present and Future. Frontiers in Microbiology : Stephen T Abedon et al 2014.
8 Bacteriophage : Genetics and microbiology :
S Mc Grath & D Van Sindern 2007
9 K Hoskin. The awful idea of accountability, inscribing people into the measurement of objects. London, International business press 1996 265-282