The spread of carbapenem-non-susceptible Klebsiella pneumoniae strains bearing different resistance determinants is a rising problem worldwide. Especially infections with KPC (Klebsiella pneumoniae carbapenemase) - producers are associated with high mortality rates due to limited treatment options. Recent clinical studies of KPC-blood stream infections revealed that colistin-based combination therapy with a carbapenem and/or tigecycline was associated with significantly decreased mortality rates when compared to colistin monotherapy. However, it remains unclear if these observations can be transferred to K. pneumoniae harboring other mechanisms of carbapenem resistance. A three-dimensional synergy analysis was performed to evaluate the benefits of a triple combination with meropenem, tigecycline and colistin against 20 K. pneumoniae isolates harboring different β-lactamases. To examine the mechanism behind the clinically observed synergistic effect, efflux properties and outer membrane porin (Omp) genes (ompK35 and ompK36) were also analyzed. Synergism was found for colistin-based double combinations for strains exhibiting high minimal inhibition concentrations against all of the three antibiotics. Adding a third antibiotic did not result in further increased synergistic effect in these strains. Antagonism did not occur. These results support the idea that colistin-based double combinations might be sufficient and the most effective combination partner for colistin should be chosen according to its MIC.

Ultraviolet (UV)-C irradiation is a promising method for microbial eradication on surfaces. Major developments have taken place in UV-C light-emitting diodes (LEDs) technology. In this study, we examined the suitability of UV-C LED-based surface disinfection in hospitals. We tested the efficacy of UV-C LED surface treatment on different microorganisms dried on a carrier surface or in a liquid solution. The influences of soiling, shading, surface material, radiation wavelength, microbial load and species on the disinfection performance were investigated. UV-C LED caused a reduction of >5 log₁₀ levels of E. coli, S. aureus and C. albicans, whereas 3 log₁₀ reduction was observed for G. stearothermophilus spores. The components of the medium led to a reduced UV-C LED efficiency compared to buffered solutions. We observed that the microbial load and the roughness of the carrier surface had a major influence on the UV-C LED disinfection efficiencies, whereas shading had no impact on inactivation. This study showed that UV-C is suitable for surface disinfection, but only under certain conditions. We showed that the main factors influencing microbial inactivation through UV-C light (e.g., intrinsic and extrinsic factors) had a similar impact when using a UV-C LED radiation source compared to a conventional UV-C lamp. However, the potential of LEDs is contributed by their adjustable wavelength and customizable geometry for the decontamination of medical devices and surfaces, and thereby their ability to overcome shading effects.

Purpose: Antimicrobial resistance is a pressing issue in Ukraine, with healthcare-associated infections caused by multidrug-resistant organisms being a major concern. A recent prospective multicenter study revealed a staggering rate of 48.4% antimicrobial resistance to carbapenems among Enterobacterales causing a healthcare-associated infection. We conducted a systematic survey to investigate the incidence rate and incidence density of carbapenemase-producing Gram-negative bacteria (CPGN) among refugees and war-wounded Ukrainians in connection with the German health system. Methods: From the onset of the war until November 2022, seven Ukrainian patients were admitted to our hospital. Upon admission, screening samples and samples from the focus of suspected infection were taken from all seven patients. The incidence rate and the incidence density of CPGN were calculated as a result of the microbiological findings. We sequenced all CPGN using Illumina technology. Results: The incidence rate of CPGN at our hospital was 0.06 for 2021 and 0.18 for 2022. All seven Ukrainian patients were infected or colonized with at least one CPGN, including K. pneumoniae (14/25), P. aeruginosa (6/25), A. baumannii (1/25), Providencia stutartii (1/25), C. freundii (1/25), and E. coli (2/25). Genomic surveillance revealed that (i) most frequently detected carbapenemases among all sequenced isolates were bla_NDM (17/25) and bla_OXA-48 (6/25), (ii) most commonly observed plasmid replicons among the K. pneumoniae isolates recovered from Ukrainian patients were Col(pHAD28) (12/14), IncHI1B(pNDM-MAR) (9/14), IncFIB(pNDM-Mar) (12/14), and (iii) clonal relation between the pathogens of the Ukrainian isolates, but not for the isolates from our hospital surveillance system. Conclusion: The rising prevalence of community-acquired colonization and infection with CPGN is having a direct effect on the infection prevention measures, such as higher number of isolations, reprocessing of patient rooms, additional microbiological testing and overall organization within hospitals.

Background: Preventing healthcare-associated infections (HAI) in neonatal intensive care units is a challenge of highest priority. For further insight into the incubator as direct patient environment and potential source for contamination, we present data correlating microbiological samples of very low birthweight infants in the form of colonization results of surveillance screenings with samples of their associated incubator in this study. Methods: Samples were taken via rectal and throat swabs of neonates as well as Polywipe^® sponges for the incubator. If the same bacterial species was found in corresponding neonate and incubator samples, whole genome sequencing via Illumina technology was performed. Results: 52 microbiological species matches were found, and 30 matches were sequenced where we found 26 clonal pairs (12 E. faecalis, 10 S. aureus, 2 E. coli, 1 E. cloacae, and 1 E. faecium). Conclusion: The combinations of measurements of weekly screenings swabs, probing of surfaces with Polywipes^®, and whole genome sequencing showed transmissions of microorganism and risk for potential non-physiological colonization of neonatal infants.

Background: Here, we describe an integrative method to detect carbapenemase-producing Gram-negative bacteria (gn-Cp) on surfaces/fomites in the patient environment. We examined environmental samples from 28 patient rooms occupied with patients who were proven to be colonised with gn-Cp by rectal screening. Methods: We took samples after 24 h, 72 h and one week. For sampling, we divided the patient environment into four parts and took samples from near- and extended patient areas. To obtain a representative bacterial swab from a larger surface, such as the patient cabinet, we used Polywipes. Bacterial DNA was isolated. Carbapenemase was detected with specific qPCR primers. Results: With this culture- and molecular-based approach, we could control the effectiveness of cleaning and disinfection in everyday clinical practice. Therefore, we could track the spread of gn-Cp within the patient room. The number of positive detections fluctuated between 30.5% (mean value positive results after 72 h) and 35.2% (after 24 h and one week). Conclusion: The method used to detect multidrug-resistant bacteria in the environment of patients by using Polywipes^TM is reliable and can therefore be used as an effective, new tool in hygiene and infection control.