Development and operation of the defence COVID-19 lab as a SARS-CoV-2 diagnostic screening capability for UK military personnel

BACKGROUND

In the face of the COVID-19 pandemic, the Defence Science and Technology Laboratory (Dstl) and Defence Pathology combined to form the Defence Clinical Lab (DCL), an accredited (ISO/IEC 17025:2017) high-throughput SARS-CoV-2 PCR screening capability for military personnel.

LABORATORY STRUCTURE AND RESOURCE

The DCL was modular in organisation, with laboratory modules and supporting functions combining to provide the accredited SARS-CoV-2 (envelope (E)-gene) PCR assay. The DCL was resourced by Dstl scientists and military clinicians and biomedical scientists.

LABORATORY RESULTS

Over 12 months of operation, the DCL was open on 289 days and tested over 72 000 samples. Six hundred military SARS-CoV-2-positive results were reported with a median E-gene quantitation cycle (Cq) value of 30.44. The lowest Cq value for a positive result observed was 11.20. Only 64 samples (0.09%) were voided due to assay inhibition after processing started.

CONCLUSIONS

Through a sustained effort and despite various operational issues, the collaboration between Dstl scientific expertise and Defence Pathology clinical expertise provided the UK military with an accredited high-throughput SARS-CoV-2 PCR test capability at the height of the COVID-19 pandemic. The DCL helped facilitate military training and operational deployments contributing to the maintenance of UK military capability. In offering a bespoke capability, including features such as testing samples in unit batches and oversight by military consultant microbiologists, the DCL provided additional benefits to the UK Ministry of Defence that were potentially not available from other SARS-CoV-2 PCR laboratories. The links between Dstl and Defence Pathology have also been strengthened, benefitting future research activities and operational responses.

Protection afforded against aerosol challenge by systemic immunisation with inactivated Francisella tularensis live vaccine strain (LVS)

BALB/c mice were immunised with inactivated Francisella tularensis live vaccine strain (LVS) and the level of protection afforded against aerosol challenge with virulent strains of F. tularensis ascertained. Intramuscular (IM) injection of inactivated LVS with an aluminium-hydroxide-based adjuvant-stimulated IgG1-biased LVS-specific antibody responses and afforded no protection against aerosol challenge with subspecies holarctica (strain HN63). Conversely, IM injection of inactivated LVS adjuvanted with preformed immune-stimulating complexes (ISCOMS) admixed with immunostimulatory CpG oligonucleotides afforded robust protection against aerosol-initiated infection with HN63. However, despite a significantly extended time-to-death relative to naïve controls, the majority of mice immunised with the most potent vaccine formulation were not protected against a low-dose aerosol challenge with subspecies tularensis (strain Schu S4). These data indicate that parenterally administered non-living vaccines can be used for effective immunisation against aerosol challenges with subspecies holarctica, although not high virulence strains of F. tularensis.

Protection afforded by heat shock protein 60 from Francisella tularensis is due to copurified lipopolysaccharide

Heat shock proteins (Hsps) have attracted significant attention as protective antigens against a range of diseases caused by bacterial pathogens. However, more recently there have been suggestions that the protective response is due to the presence of peptide components other than Hsps. We have shown that mice that had been immunized with purified heat shock protein 60 (Hsp60) isolated from Francisella tularensis were protected against a subsequent challenge with some strains of the bacterium. However, this protection appeared to be due to trace amounts of lipopolysaccharide, which were too low to be detected by using the Limulus amoebocyte lysate assay. This finding raises the possibility that the protection afforded by other bacterial Hsp60 proteins may be due to trace quantities of polysaccharide antigens carried by and acting in conjunction with the Hsps.

Sulphasalazine treatment and the colorectal mucosa-associated flora in ulcerative colitis

AIM

To study the influence of sulphasalazine treatment on the mucosa-associated bacterial flora of rectal biopsy tissue specimens in patients with ulcerative colitis.

PATIENTS

Twenty-four patients had newly diagnosed active ulcerative colitis; 20 patients had acute relapse of ulcerative colitis (10 not taking maintenance sulphasalazine); (40 patients had quiescent ulcerative colitis; 21 not taking maintenance sulphasalazine). The influence of 3 weeks of sulphasalazine treatment on the mucosa-associated flora was studied in the patients presenting with active disease.

RESULTS

Comparison of patients according to sulphasalazine usage revealed few differences in the mucosal flora. In patients with quiescent ulcerative colitis, Escherichia coli was found at lower counts in patients taking maintenance sulphasalazine; however, this effect was not evident in patients with active disease. Inconsistent changes in other facultatives were seen between the two active disease groups, particularly for a miscellaneous group of unidentified Gram-positive rods. Three patients, all receiving sulphasalazine, were colonized with Clostridium difficile, but this did not appear to influence their disease.

CONCLUSION

Sulphasalazine treatment in ulcerative colitis causes only minor disturbance to the populations of bacteria colonizing the colorectal mucosa.

Adhesive and hydrophobic properties of Escherichia coli from the rectal mucosa of patients with ulcerative colitis

The adherent properties and hydrophobicity of Escherichia coli isolates have been compared from the rectal mucosa of patients with active and inactive ulcerative colitis and from a control patient group. Patients with active colitis were colonised less frequently and with lower numbers of E coli than were control patients. Mannose resistant adhesion to HEp-2 cells was determined for 124 isolates of E coli and surface hydrophobicity was estimated by salt agglutination in 96 of these isolates. There was no significant difference in the distribution of adherent strains between the colitis patient groups or with disease activity. E coli from the control patients were marginally less adhesive than those from colitics. The hydrophobicity of isolates did not differ significantly between colitic and control groups nor were there significant differences correlated with disease activity. Furthermore, for these mucosal E coli isolates, hydrophobicity and mannose resistant adhesion were unrelated characteristics.

The rectal mucosa-associated microflora in patients with ulcerative colitis

The rectal mucosa-associated flora (MAF) of patients with ulcerative colitis has been studied in 25 patients with newly diagnosed disease, 20 with relapse of existing disease, and 44 who were in remission. Patients with active disease were re-examined twice during treatment. The MAF was simpler and less dense than the microflora of faeces. Obligate anaerobes usually predominated in the MAF although the ratio of obligate anaerobes to facultative species was lower than that found in faeces. Viable counts of the total flora and of its constituent genera varied considerably between patients. Counts of the total flora, of obligate anaerobes (including bifidobacteria, eubacteria and clostridia), and facultative organisms and micro-aerobes (enterobacteria and lactobacilli) were reduced in patients with active disease compared with those with inactive disease; corresponding carriage rates were also lower. Counts and carriage rates increased during treatment and approached those found in quiescent disease. The alterations in the MAF were especially marked in patients experiencing their first attack of ulcerative colitis. The relationship between these alterations and the aetiology and pathogenesis of this disease remains unclear.

Giant gas filled cysts of the sigmoid colon: a report of two cases

Two case reports of giant gas filled cysts of the sigmoid colon are presented. It is considered that radiology provides the only useful and conclusive diagnostic investigation. In one of the cases, operative confirmation was obtained. In the other, the radiological appearances are considered to be diagnostic.