Microbiological Profile of Fracture Related Infection at a UK Major Trauma Centre

Fracture Related Infection (FRI) represents one of the biggest challenges for Trauma and Orthopaedic surgery. A better understanding of the microbiological profile should assist with decision-making and optimising outcomes. Our primary aim was to report on the microbiological profile of FRI cases treated over a six-year period at one of Europe's busiest trauma centres. Secondarily, we sought to correlate our findings with existing anti-microbiological protocols and report on diagnostic techniques employed in our practice. All adult cases of FRI treated in our institution between 2016 and 2021 were identified, retrospectively. We recorded patient demographics, diagnostic strategies, causative organisms and antibiotic susceptibilities. There were 330 infection episodes in 294 patients. A total of 463 potentially pathogenic organisms (78 different species) were identified from cultures, of which 57.2% were gram-positive and 39.7% gram-negative. Polymicrobial cultures were found in 33.6% of cases and no causative organism was found in 17.5%. The most prevalent organisms were Staphylococcus aureus (24.4%), coagulase-negative Staphylococci (14%), Pseudomonas aeruginosa (8.2%), Enterobacter species (7.8%) and Escherichia coli (6.9%). Resistant gram-positive organisms (methicillin resistant Staphylococcus aureus or vancomycin-resistant Enterococci) were implicated in 3.3% of infection episodes and resistant gram-negatives (extended-spectrum beta-lactamase, ampC or carbapenemase-producing bacteria) in 13.6%. The organisms cultured in 96.3% of infection episodes would have been covered by our empirical systemic antibiotic choice of teicoplanin and meropenem. To our knowledge, this is the largest reported single-centre cohort of FRIs from a major trauma centre. Our results demonstrate patterns in microbiological profiles that should serve to inform the decision-making process regarding antibiotic choices for both prophylaxis and treatment.

Extraspinal articular tuberculosis: An 11-year retrospective study of demographic features and clinical outcomes in East London

OBJECTIVES

To describe demographic features, clinical outcomes and diagnostic delay amongst patients with extra-spinal articular tuberculosis (TB) in a low-incidence setting.

METHODS

Cases of TB treated at our institution between 2004 and 2014 were identified via the London TB register (LTBR). Demographic features of extra-spinal articular TB cases were compared to controls with TB at all other sites. For articular cases (excluding individuals <16 years or with spinal TB without peripheral joint involvement) clinical data were retrospectively collected.

RESULTS

6,146 TB patients were identified over the study period; 146 (2.4%) cases had extra-spinal articular infection. There was no difference in median age between extra-spinal articular TB cases and controls with TB at other sites (31 vs 32 years, p = 0.57). Articular cases were more likely to be male (70.6% vs 59.5%, p = 0.007), Bangladeshi (28.7% vs 18.0%) or Pakistani (24.0% vs 16.1%) and were less likely to be Black-African (9.5% vs 19.8%) (p < 0.001). 93 cases were included in the case series; 85 (88.5%) were migrants and 83 (89.2%) were South Asian. Knee and elbow joints were affected in 22 (23.7%) and 18 (19.4%) cases respectively. The median durations of pre-healthcare and healthcare associated delay were 16 and 6 weeks respectively. Where mycobacterial culture was performed, 57/75 (76%) were positive for Mycobacterium tuberculosis. 86 (92.5%) cases received standard quadruple therapy for a median of 6 months (IQR 6-9). Recurrence of TB infection occurred in 4 (4.3%) cases and there were no TB related deaths. Seven (7.6%) cases required surgical intervention.

CONCLUSIONS

Extra-spinal articular TB more commonly affected men and people of South Asian ethnicity. Significant diagnostic delays were identified, including avoidable healthcare-associated delays.

Evaluation of 2 commercial anti-SARS-CoV-2 antibody assays in an immunocompetent and immunocompromised inpatient population with COVID-19

INTRODUCTION

During the COVID-19 pandemic, widespread introduction of SARS-CoV-2 antibody testing was introduced without a full understanding of the assays performance or the antibody kinetics following infection with SARS-CoV-2.

METHODS

We performed an evaluation of 2 anti-SARS-CoV-2 antibody assays with a more detailed look into the effect of immune status on antibody sensitivity.

RESULTS

Both assays demonstrated 100% specificity. The overall sensitivity of the Roche was 92.1% at ≥14 days and 94.8% at ≥21 days, and the overall sensitivity of the Abbott was 94.4% at ≥14 days and 98.2% at ≥21 days. 7/41 (17%) of patients included in this cohort were immunocompromised. Seroconversion was seen less commonly in the immunocompromised (4/7 [57.1%] seroconverted) and after excluding these patients 100% sensitivity was seen in both assays at ≥21 days.

DISCUSSION

Performance of both assays in the immunocompetent appeared excellent after 21 days postsymptom onset. Both assays are highly specific.

Hospital outbreak of carbapenem-resistant Enterobacterales associated with a blaOXA-48 plasmid carried mostly by Escherichia coli ST399

A hospital outbreak of carbapenem-resistant Enterobacterales was detected by routine surveillance. Whole genome sequencing and subsequent analysis revealed a conserved promiscuous bla_OXA-48 carrying plasmid as the defining factor within this outbreak. Four different species of Enterobacterales were involved in the outbreak. Escherichia coli ST399 accounted for 35 of all the 55 isolates. Comparative genomics analysis using publicly available E. coli ST399 genomes showed that the outbreak E. coli ST399 isolates formed a unique clade. We developed a mathematical model of pOXA-48-like plasmid transmission between host lineages and used it to estimate its conjugation rate, giving a lower bound of 0.23 conjugation events per lineage per year. Our analysis suggests that co-evolution between the pOXA-48-like plasmid and E. coli ST399 could have played a role in the outbreak. This is the first study to report carbapenem-resistant E. coli ST399 carrying blaOXA-48 as the main cause of a plasmid-borne outbreak within a hospital setting. Our findings suggest complementary roles for both plasmid conjugation and clonal expansion in the emergence of this outbreak.

Corynebacterium kroppenstedtii breast abscesses in context, a retrospective cohort study

Corynebacterium kroppenstedtii breast abscesses and granulomatous mastitis have gained increased recognition in the 20 years since their association was first described. No studies to date have described this organism in the context of all breast abscess pathogens. We retrospectively reviewed 160 community-acquired breast abscess samples from 135 patients in a 3 year period, describing the organisms isolated along with risk factors, site of infection and outcomes. We compared patient subgroups with acute and chronic abscesses, the latter defined as having a requirement for repeat aspiration more than 1 month apart. The prevalence of C. kroppenstedtii breast abscesses was 8 % in all patients (11/135), rising to 32 % in chronic abscesses (10/31), but only 1 % in acute abscesses (1/104; P<0.01). Only 10 % (1/10) of patients with C. kroppenstedtii chronic abscesses were smokers, whereas 75 % of patients (15/20) with non-C. kroppenstedtii chronic abscesses were smokers (P=0.01). C. kroppenstedtii should be considered in recurrent and prolonged infections, especially in non-smokers, and diagnostic methods altered accordingly. Identifying C. kroppenstedtii provides diagnostic clarity and alters management with recommendations for longer courses of treatment using non-beta-lactam antibiotics.