From December 2004 to March 2005, 27 Klebsiella pneumoniae clinical isolates that were positive by the imipenem-EDTA double-disk synergy test and that exhibited a single macrorestriction pattern were recovered in two distinct Greek hospitals. The isolates carried a transferable bla _VIM-1 metallo-β-lactamase gene in a class 1 integron. Reverse transcriptase PCR showed that the gene was similarly expressed in low- and high-level carbapenem-resistant isolates, indicating the existence of additional resistance mechanisms. The clonal spread of VIM-1-producing K. pneumoniae strains in distinct regions where up to now bla _VIM-2 and bla _VIM-4 alleles were common is worrisome.

Co-infections have an unknown impact on the morbidity and mortality of the new clinical syndrome called coronavirus disease 2019 (COVID-19). The syndrome is caused by the new pandemic coronavirus SARS-CoV-2 and it is probably connected with severe traces in the elements of the immune system. Apart from possible Aspergillus infections, particularly in patients with acute respiratory distress syndrome (ARDS), other fungal infections could occur, probably more easily, due to the immunological dysregulation and the critical condition of these patients. Probiotic preparations of Saccharomyces are broadly used for the prevention of antibiotic-associated complications, especially in the intensive care units (ICU). On the other hand, Saccharomyces organisms are reported as agents of invasive infection in immunocompromised or critically ill patients. We report two cases of bloodstream infection by Saccharomyces in two patients hospitalised in the ICU, due to severe COVID-19, after Saccharomyces supplementation.

Changes in hospitals’ daily practice due to COVID-19 pandemic may have an impact on antimicrobial resistance (AMR). We aimed to assess this possible impact as captured by the Greek Electronic System for the Surveillance of Antimicrobial Resistance (WHONET-Greece). Routine susceptibility data of 17,837 Gram-negative and Gram-positive bacterial isolates from blood and respiratory specimens of hospitalized patients in nine COVID-19 tertiary hospitals were used in order to identify potential differences in AMR trends in the last three years, divided into two periods, January 2018–March 2020 and April 2020–March 2021. Interrupted time-series analysis was used to evaluate differences in the trends of non-susceptibility before and after the changes due to COVID-19. We found significant differences in the slope of non-susceptibility trends of Acinetobacter baumannii blood and respiratory isolates to amikacin, tigecycline and colistin; of Klebsiella pneumoniae blood and respiratory isolates to meropenem and tigecycline; and of Pseudomonas aeruginosa respiratory isolates to imipenem, meropenem and levofloxacin. Additionally, we found significant differences in the slope of non-susceptibility trends of Staphylococcus aureus isolates to oxacillin and of Enterococcus faecium isolates to glycopeptides. Assessing in this early stage, through surveillance of routine laboratory data, the way a new global threat like COVID-19 could affect an already ongoing pandemic like AMR provides useful information for prompt action.

A Pseudomonas aeruginosa clinical isolate that exhibited high-level carbapenem resistance and produced metallo-β-lactamase (MBL) was recovered from a Greek patient. This study was conducted to determine the underlying mechanisms that conferred the carbapenem resistance phenotype. MICs were determined by Etest and Etest MBL. PCR assays were performed for identification of bla_VIM-type, other antibiotic resistance and efflux pump genes and mapping of class 1 integrons. Expression of efflux pump genes was quantified by real-time PCR. Nucleotide sequencing was used to determine the bla_VIM allele. The location of the MBL allele was investigated by mating experiments, plasmid analysis and hybridization studies. The isolate was highly carbapenem-resistant (MICs of imipenem and meropenem were 512 and 128 mg/L, respectively) and multidrug-resistant. It harboured the β-lactamase genes bla_VIM-4 and bla_P1b in a novel class 1 integron named InV4P1, and a second integron with aac(6’)-Ib and bla_OXA-35 gene cassettes. The isolate was deficient in porin OprD and overexpressed efflux pumps MexAB-OprM and MexXY-OprM. Conjugation experiments failed to detect transferable MBL determinants, plasmids were not visualized and bla_VIM was detected by PCR in the chromosomal band. Multiple carbapenem resistance mechanisms are demonstrated to coexist in a single P. aeruginosa isolate and might confer the high-level carbapenem resistance.

Polymyxins are commonly used as the last resort for the treatment of MDR Acinetobacter baumannii and Klebsiella pneumoniae nosocomial infections; however, apart from the already known toxicity issues, resistance to these agents is emerging. In the present study, we assessed the in vitro synergistic activity of antimicrobial combinations against carbapenem-resistant and colistin-resistant A. baumannii and K. pneumoniae in an effort to provide more options for their treatment. Two hundred A. baumannii and one hundred and six K. pneumoniae single clinical isolates with resistance to carbapenems and colistin, recovered between 1 January 2021 and 31 July 2022,were included. A. baumannii were tested by the MIC test strip fixed-ratio method for combinations of colistin with either meropenem or rifampicin or daptomycin. K. pneumoniae were tested for the combinations of colistin with meropenem and ceftazidime/avibactam with aztreonam. Synergy was observed at: 98.99% for colistin and meropenem against A. baumannii; 91.52% for colistin and rifampicin; and 100% for colistin and daptomycin. Synergy was also observed at: 73.56% for colistin and meropenem against K. pneumoniae and; and 93% for ceftazidime/avibactam with aztreonam. The tested antimicrobial combinations presented high synergy rates, rendering them valuable options against A. baumannii and K. pneumoniae infections.

Carbapenemase-producing Klebsiella pneumoniae (CPKP) emerged in Greece in 2002 and became endemic thereafter. Driven by a notable variability in the phenotypic testing results for carbapenemase production in K. pneumoniae isolates from the intensive care units (ICUs) of our hospital, we performed a study to assess the molecular epidemiology of CPKP isolated between 2016 and 2019 using pulse-field gel electrophoresis (PFGE) including isolates recovered from 165 single patients. We investigated the molecular relatedness among strains recovered from rectal surveillance cultures and from respective subsequent infections due to CPKP in the same individual (48/165 cases). For the optimal interpretation of our findings, we carried out a systematic review regarding the clonality of CPKP isolated from clinical samples in ICUs in Europe. In our study, we identified 128 distinguishable pulsotypes and 17 clusters that indicated extended dissemination of CPKP within the hospital ICU setting throughout the study period. Among the clinical isolates, 122 harbored KPC genes (74%), 2 harbored KPC+NDM (1.2%), 38 harbored NDM (23%), 1 harbored NDM+OXA-48 (0.6%), 1 harbored NDM+VIM (0.6%) and 1 harbored the VIM (0.6%) gene. Multiple CPKP strains in our hospital have achieved sustained transmission. The polyclonal endemicity of CPKP presents a further threat for the selection of pathogens resistant to last-resort antimicrobial agents.