Acquired carbapenemase-producing organisms in North London: health inequalities and healthcare associations, 2016-2023.

Background: Acquired carbapenemase-producing organisms (CPO), particularly acquired carbapenemase-producing Enterobacterales (CPE), pose a major public health challenge due to limited treatment options. Objectives: To evaluate associations between CPO positivity and ethnic group, Index of Multiple Deprivation (IMD) and healthcare exposure, and to apply a statistical model to quantify these relationships. Patients and methods: A retrospective observational analysis of CPO cases identified at a London teaching hospital (2016-2023) was conducted. Microbiological, clinical and demographic data were reviewed. Cases were classified as hospital onset healthcare associated (HOHA), community onset healthcare associated (COHA) or community onset community associated (COCA). Socioeconomic status was assessed using IMD. Positive and negative cases were compared by medical specialty, age, sex and ethnicity. Odds ratios for risk factors were estimated, and a mixed-effects logistic regression model was applied. Results: A total of 679 CPO isolates were detected in 651 patients. OXA-48-like (56.1%) and NDM (38.9%) were the predominant carbapenemases. HOHA accounted for 42.1% of cases, COCA for 39% and COHA for 18.9%. Renal, vascular and liver specialties had the highest proportions of CPO-positive patients. Females had 0.8 times the odds of CPO positivity compared with males, and risk increased with age until mid-life. White British patients had 0.62 times the odds of CPO positivity compared with other ethnic groups. IMD analysis showed a bell-shaped distribution, with highest prevalence in mid-deprivation quintiles. Conclusion: CPOs arise from both healthcare-associated and community pathways. Differentiating HOHA, COHA and COCA enhances understanding of local epidemiology and supports targeted infection-prevention strategies including medical specialties.