Household transmission of non-toxigenic diphtheria toxin gene-bearing Corynebacterium diphtheriae following a cluster of cutaneous cases in a specialist outpatient setting.

Introduction. Combination of PCR and Elek testing to identify toxigenic corynebacteria has revealed organisms described as non-toxigenic toxin-gene bearing (NTTB) Corynebacterium diphtheriae or C. ulcerans (i.e. PCR tox positive; Elek negative). These organisms carry part or all of tox, but are unable to express diphtheria toxin (DT) and present a challenge to clinical and public health case management.Gap analysis/Hypothesis. There are few data on the theoretical risk of NTTB reversion to toxigenicity. This unique cluster and subsequent epidemiologically linked isolates allowed the opportunity to determine any change in DT expression status.Aim. To characterize a cluster of infections due to NTTB in a skin clinic and subsequent cases in two household contacts.Methodology. Epidemiological and microbiological investigations were carried out according to existing national guidance at the time. Susceptibility testing used gradient strips. The tox operon analysis and multi-locus sequence typing (MLST) was derived from whole-genome sequencing. Alignment of the tox operon and phylogenetic analyses were performed using clustalW, mega, the public core-genome MLST (cgMLST) scheme and an in-house bioinformatic single nucleotide polymorphism (SNP) typing pipeline.Results. Isolates of NTTB C. diphtheriae were recovered from four cases (cases 1 to 4) with epidermolysis bullosa attending the clinic. Two further isolates were subsequently recovered from case 4, >18 months later, and from two household contacts (cases 5 and 6) after a further 18 months and 3.5 years, respectively. All eight strains were NTTB C. diphtheriae biovar mitis, belonged to the same sequence type (ST-336) with the same deletion in tox. Phylogenetic analysis showed relatively high diversity between the eight strains with 7-199 SNP and 3-109 cgMLST loci differences between them. The number of SNPs between the three isolates from case 4 and two household contacts (cases 5 and 6) was 44-70 with 28-38 cgMLST loci differences.Conclusions. We report a cluster of NTTB C. diphtheriae cases in a skin clinic and evidence of onward household transmission. We conclude the deletion in the tox was responsible for the non-expression of DT. There was no evidence of reversion to DT expression over the 6.5 year period studied. These data informed revision to guidance in the management of NTTB cases and their contacts in the UK.

Attendance at London workplaces after symptom onset: a retrospective cohort study of staff members with confirmed COVID-19.

BACKGROUND: Coronavirus disease (COVID)-secure workplace guidance, including the prompt self-isolation of those with COVID-19 symptoms, is fundamental to disease control in workplaces. Despite guidance, a large number of workplace outbreaks have been observed. This study aimed to identify the proportion of symptomatic staff members attending workplaces after symptom onset or testing, and associated factors. METHODS: This study of symptomatic COVID-19 cases associated with London workplaces used London Coronavirus Response Centre (LCRC) records from routine telephone calls with cases and employers, from 17th July to 10th September. For each case, symptoms, date of onset, date of testing and the last attendance at work were extracted. Univariable logistic regression was performed to investigate whether age, gender or occupation was associated with workplace attendance after the onset of symptoms. RESULTS: Out of 130 symptomatic COVID-19 cases, 42 (32.3%) attended the workplace after their reported date of symptom onset, including 16 (12.3%) with recorded COVID-19 symptoms. Five staff members attended after COVID-19 testing. Males were 66% less likely to attend the workplace after the onset of COVID-19 symptoms compared to females (odds ratio 0.34, P = 0.05). Age and occupation were not predictive for workplace attendance after the onset of symptoms. CONCLUSION: A minority of symptomatic cases attended the workplace after the onset of COVID-19 symptoms, with a smaller proportion attending after testing. Males appeared less likely to attend the workplace after the onset of COVID-19 symptoms. This study highlights the need for ongoing COVID-19 secure workplace practices and prompt self-isolation after COVID-19 symptom onset or testing.

Pragmatic management of programmatic vaccination errors--lessons learnt from incidents in London.

Correct storage, handling and administration of vaccines are vital components of a successful immunisation programme. However, with the large number of different healthcare professionals now involved in delivering the vaccine programme on a daily basis, it is inevitable that programmatic errors will occur. Decisions as to how best to rectify these errors can be difficult however, as often they are unprecedented and there may be no hard evidence on which to base their management. These decisions must therefore be based on what is known and any available previous experience. They also often take place in an environment of concern about litigation and liability which puts pressure on health care workers to take a defensive or conservative approach. Management decisions may ultimately also have to be a pragmatic choice based on the individual situation and what is deemed to be the best way to minimise adverse reactions, ensure patients are adequately protected and maintain public confidence in the immunisation programme. Here, we describe our experiences of managing vaccine programmatic errors and some of the many factors that we had to consider.