An outbreak of multi-drug-resistant Acinetobacter baumannii on a burns ICU and its control with multi-faceted containment measures.

BACKGROUND: Patients in burns centres are at high risk of acquiring multi-drug-resistant organisms (MDROs) due to the reduced skin barrier and long hospital stay. METHODS: This study reports the investigation and control of an outbreak of MDR Acinetobacter baumannii in a burns centre. The 27 patients hospitalized in the centre during the outbreak were screened regularly, and a total of 132 environmental samples were analysed to identify a potential source. Fourier-transform infra-red (FT-IR) spectroscopy and multi-locus sequence typing were applied to characterize the outbreak strain. RESULTS: Between August and November 2022, the outbreak affected eight patients, with 11 infections and three potentially related fatal outcomes. An interdisciplinary and multi-professional outbreak team implemented a bundle strategy with repetitive admission stops, isolation precaution measures, patient screenings, enhanced cleaning and disinfection, and staff education. FT-IR spectroscopy suggested that the outbreak started from a patient who had been repatriated 1 month previously from a country with high prevalence of MDR A. baumannii. Environmental sampling did not identify a common source. Acquisition of the outbreak strain was associated with a higher percentage of body surface area with burn lesions ≥2a [per percent increase: odds ratio (OR) 1.05, 95% confidence interval (CI) 0.99-1.12; P=0.09], and inversely associated with a higher nurse-to-patient ratio (per 0.1 increase: OR 0.34, 95% CI 0.10-1.12; P=0.06). CONCLUSIONS: Burn patients with a higher percentage of body surface area with burn lesions ≥2a are at high risk of colonization and infection due to MDROs, particularly during periods of high workload. A multi-faceted containment strategy can successfully control outbreaks due to MDR A. baumannii in a burns centre.

Fourier-transform infrared spectroscopy for typing of vancomycin-resistant Enterococcus faecium: performance analysis and outbreak investigation.

Vancomycin-resistant Enterococci, mainly Enterococcus faecium (VREfm), are causing nosocomial infections and outbreaks. Bacterial typing methods are used to assist in outbreak investigations. Most of them, especially genotypic methods like multi-locus sequence typing (MLST), whole genome sequencing (WGS), or pulsed-field gel electrophoresis, are quite expensive and time-consuming. Fourier-transform infrared (FT-IR) spectroscopy assesses the biochemical composition of bacteria, such as carboxyl groups in polysaccharides. It is an affordable technique and has a faster turnaround time. Thus, the aim of this study was to evaluate FT-IR spectroscopy for VREfm outbreak investigations. Basic performance requirements like reproducibility and the effects of incubation time were assessed in distinct sample sets. After determining a FT-IR spectroscopy cut-off range, the clustering agreement between FT-IR and WGS within a retrospective (n: 92 isolates) and a prospective outbreak (n: 15 isolates) was investigated. For WGS an average nucleotide identity (ANI) cut-off score of 0.999 was used. Basic performance analysis showed reproducible results. Moreover, FT-IR spectroscopy readouts showed a high agreement with WGS-ANI analysis in clinical outbreak investigations (V-measure 0.772 for the retrospective and 1.000 for the prospective outbreak). FT-IR spectroscopy had a higher discriminatory power than MLST in the outbreak investigations. After determining cut-off values to achieve optimal resolution, FT-IR spectroscopy is a promising technique to assist in outbreak investigation as an affordable, easy-to-use tool with a turnaround time of less than one day. IMPORTANCE Vancomycin-resistant Enterococci, mainly Enterococcus faecium (VREfm), are a frequent cause of nosocomial outbreaks. Several bacterial typing methods are used to track transmissions and investigate outbreaks, whereby genome-based techniques are used as a gold standard. Current methods are either expensive, time-consuming, or both. Additionally, often, specifically trained staff needs to be available. This study provides insight into the use of Fourier-transform infrared (FT-IR) spectroscopy, an affordable, easy-to-use tool with a short turnaround time as a typing method for VREfm. By assessing clinical samples, this work demonstrates promising results for species discrimination and reproducibility. FT-IR spectrosopy shows a high level of agreement in the analysis of VREfm outbreaks in comparison with whole genome sequencing-based methods.