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Konstantinos Kostikas,1 Katerina Dimakou,2 Konstantinos Gourgoulianis,3 Mina Gaga,4 Dimosthenis Papapetrou,5 Georgios Tsoukalas,6 Panagiotis Chatziapostolou,7 Antonios Antoniadis,8 Georgios Meletis,9 Efstathia Evangelopoulou,10 Panagiota Styliara,11 Ilektra Karypidou,12 Athena Gogali,1 Konstantinos Kalafatakis,13,14 Nikolaos Tzanakis15 1Respiratory Medicine Department, University Hospital of Ioannina, Ioannina, Greece; 2 5th Respiratory Medicine Department, General Hospital for Chest Diseases of Athens “SOTIRIA”, Athens, Greece; 3Department of Respiratory Medicine, University of Thessaly, Larissa, Greece; 4 7th Respiratory Medicine Department, General Hospital for Chest Diseases of Athens “SOTIRIA”, Athens, Greece; 5Iatriko Athinon, Paleo Faliro, Attiki, Greece; 6 4th Respiratory Medicine Department, General Hospital for Chest Diseases of Athens “SOTIRIA”, Athens, Greece; 7Department of Pulmonary Medicine, Euromedica General Clinic, Thessaloniki, Greece; 8Department of Pulmonary Medicine, General Hospital of Serres, Serres, Greece; 9Department of Pulmonary Medicine, General Hospital of Heraklion “VENIZELEIO”, Heraklion, Greece; 10Respiratory Medicine Department, General Hospital of Nikaia “ST. PANTELEIMON”, Piraeus, Greece; 11Menarini Hellas, Athens, Greece; 12Department of Pulmonary Medicine, General Hospital of Thessaloniki “GEORGIOS PAPANIKOLAOU”, Thessaloniki, Greece; 13Department of Informatics & Telecommunications, University of Ioannina, Arta, Greece; 14Barts and the London School of Medicine & Dentistry, Queen Mary University of London (Malta Campus), Victoria, Gozo, Malta; 15Department of Respiratory Medicine, University General Hospital of Heraklion, Heraklion, GreeceCorrespondence: Konstantinos Kostikas, Respiratory Medicine & Head of Respiratory Medicine Department, University Hospital of Ioannina, Ioannina, Greece, Tel +30-2651007536 ; +30-6944780616, Email ktkostikas@gmail.com; ktkostikas@uoi.grPurpose: The rationale of this study was to investigate the prevalence of daily and night symptoms and quality of sleep in Greek COPD patients as a means to evaluate their response to treatment with the fixed dose combination of aclidinium/formoterol (administered through the Genuair® device).Patients and Methods: This study was a multicenter, nationwide, non-interventional, observational study in 2105 patients suffering from COPD, who have recently started treatment with aclidinium/formoterol. Patients were attending to two visits, one baseline and a final visit, 3 months later. Different variables have been collected on either the baseline or the final visit or both: demographics, vital sign measurements, COPD-related medical history parameters, comorbidities, COPD assessment test (CAT), COPD severity based on spirometry measurements, COPD stage based on the ABCD assessment approach proposed by the 2019 Global Initiative for Chronic Obstructive Lung Disease (GOLD), COPD treatment report, and severity of early-morning, daytime and night-time COPD-related symptoms. Reasons for prescribing aclidinium/formoterol, satisfaction of patients to the treatment, as well as their compliance have also been recorded.Results: After 3 months on aclidinium/formoterol, 50.1% of the patients experienced an improvement in their early-morning symptoms. Furthermore, 49.9% of them experienced an improvement in their daily symptoms, 44.9% improved their night-time symptoms and 43.2% reduced the frequency of overnight sleep disruptions due to COPD symptoms. These favorable outcomes apply mainly to GOLD Groups B–D. Treatment with aclidinium/formoterol improved on average the pre-bronchodilation FEV1% pred by 3.18%, the post-bronchodilation FEV1% pred by 2.78% and reduced CAT score by 5.22 points. Satisfaction with using aclidinium/formoterol across patients was high, as well as compliance to therapy.Conclusion: Aclidinium/formoterol provided significant benefits on the quality of life of COPD patients by reducing the morning, daytime and the night-time symptoms and symptom burden in GOLD Groups B–D, and activity impairment under real-life conditions in all GOLD ABCD groups.Keywords: COPD, dual-bronchodilation therapy, aclidinium/formoterol, daytime and night-time symptoms, GOLD ABCD classification

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen associated with a range of nosocomial infections. This microorganism is noted for its intrinsic resistance to antibiotics and for its ability to acquire genes encoding resistance determinants. Among the beta-lactam antibiotics, carbapenems with antipseudomonal activity are important agents for the therapy of infections due to P. aeruginosa. The development of carbapenem resistance among P. aeruginosa strains is multifactorial. Plasmid or integron-mediated carbapenemases, increased expression of efflux systems, reduced porin expression and increased chromosomal cephalosporinase activity have all been defined as contributory factors. Phenotypic tests and molecular techniques are used for the characterization of the resistance determinants. The isolation of carbapenem resistant strains is alarming and requires the implementation of strict infection control measures in order to prevent the spread of carbapenemase encoding genes to unrelated clones or to other bacterial species. [ABSTRACT FROM AUTHOR]

Smoking habits differ in different professions, with social status and among populations. An effective anti-smoking campaign should be based on knowl edge of the attitudes and characteristics of the target population. Our aim was to study the smoking habits and attitudes towards smoking of the employees of the University Hospital of Crete, prior to commencing an anti-smoking cam paign. A questionnaire consisting of 38 questions, was distributed to 450 out of 500 Hospital employees and was correctly completed by 400 of them (88.7%). The mean age of responders was 29.8 ± 6.8 years; 148 were males and 252 females. We found that 219 were smokers (55%): 89 males (58%) and 130 females (51.6%); 61 were ex-smokers (15.2%). All smokers smoked ciga rettes, with a mean consumption of 22.3 ± 12.9 cigarettes per day. The mean age at which the smoking habit began was 18.6 ± 3.4 years. Parents of smok ers and of non-smokers were smokers themselves in equal percentages (44% vs. 43.4%, respectively). 95.7% of the employees were aware that smoking was harmful to their health and 64% supported the idea of abandoning smoking in the hospital (46.2% of the smokers). A high percentage of responders (80.5%) wanted to stop smoking (79% had already tried once). A significant negative relationship between the age at which the smoking began and severity of smok ing was found (r = -0.205, p < 0.001). We concluded that smoking is very common among hospital employees in Greece including doctors, nurses and medical students. However, the majority of them wish to stop. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented which discusses the etiology and diagnosis of pneumococcosuria in a 4-year old girl.

Background: Studies link multidrug-resistant organism (MDRO) rectal colonization to increased infection risk, data from Greece, a country with high rates of MDRO, are limited., Methods: We assessed bloodstream infection (BSI) risk following rectal colonization by MDROs across three Greek hospitals (2019-2022)., Results: Of 4,370 inpatients, 31.1% were colonized by carbapenem-resistant Enterobacterales (CRE), 30.1% carbapenem-resistant Acinetobacter baumannii (CRAB), 5.8% carbapenem-resistant Pseudomonas aeruginosa (CRPA), 28.4% vancomycin-resistant enterococci (VRE). Subsequent BSI from the same MDRO species was developed in 15.6% of CRE, 19.7% of CRAB, 9.2% of CRPA and 3.5% of VRE carriers. Previous rectal colonization increases significantly MDRO BSI risk [RR (95%CI): CRE 5.2 (3.9-6.8), CRAB 2.7 (2.2-3.3), CRPA 9.6 (5.8-16.0), VRE 2.5 (1.5-4.2)]., Conclusion: Clinicians should consider MDRO carriage information for selecting empiric treatment., Competing Interests: Declarations. Ethical approval: Ethical approval was not obtained for the study since it utilized data from routine surveillance and was not thus necessary. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The aim of the study was to evaluate the performance of the BCID2 FilmArray panel in relation to blood culture. 162 positive blood cultures were subjected to both classical microbiology methods and the FilmArray nested multiplex PCR. The BCID2 panel showed 96.7% sensitivity, 99% specificity and 99% accuracy., Competing Interests: Declaration of competing interest There is no any conflict of interest, (Copyright © 2024 Elsevier Inc. All rights reserved.)

The present study aimed to determine the resistance mechanisms and clonal relationships among vancomycin-resistant Enterococci (VRE) isolated in AHEPA University Hospital during the pandemic year 2021. Overall, 140 clinical VRE were isolated during the study period and 44 were randomly selected for molecular analysis. A multiplex PCR was employed to detect vancomycin resistance genes (vanA, vanB, vanC, vanD, vanE, vanG) using specific primers. Additionally, pulsed-field gel electrophoresis (PFGE) was performed to assess the clonal relatedness of the selected isolates. The multiplex PCR showed that 36 of the 44 studied strains (81.9%) harbored the vanA gene whereas, 7 of 44 (15.9%) co-harbored the vanA and vanB resistance genes; one isolate had a negative PCR result. PFGE analysis unveiled 37 distinct electrophoretic patterns among the 44 VRE isolates with a similarity threshold of 75%. These patterns were clustered into 4 distinct branches. Our findings indicate a polyclonal distribution of vanA genes among the studied isolates and the notable concomitant presence of vanA/vanB genotypes. Furthermore, these results highlight the worsening that took place during the COVID-19 pandemic period regarding antibiotic resistance rates, underscoring the imperative need for stringent infection control measures and active surveillance.

Background: Noninvasive ventilation (NIV) has been the cornerstone for managing acute exacerbations of COPD (AECOPD) with hypercapnic respiratory failure. Nasal high flow (NHF) oxygen therapy has emerged as a potential alternative, offering a more tolerable modality with promising outcomes. The aim of the present study was to evaluate whether NHF respiratory support is noninferior to NIV with respect to treatment failure, in patients with mild-to-moderate hypercapnic AECOPD., Methods: In this multi-center, randomized, noninferiority trial, 105 patients with AECOPD and respiratory failure type II were enrolled. Participants were randomly assigned to receive either NHF therapy or NIV. The primary endpoint was the frequency of treatment failure, defined as the need for intubation and invasive mechanical ventilation or a switch to the alternative treatment group. Secondary endpoints included changes in respiratory parameters, patient comfort indicators, and the occurrence of complications., Results: The findings revealed no significant difference in the primary outcome between the groups, with a treatment failure rate of 19.6 % (10 out of 51) in the NHF group and 14.8 % (8 out of 54) in the NIV group. Interestingly, NHF users reported significantly lower levels of dyspnea and discomfort at multiple follow-up points. Despite the differences in patient comfort, respiratory parameters such as respiratory rate, arterial blood gases, and use of accessory muscles of respiration showed no significant disparities between the groups throughout the study period., Conclusions: NHF therapy was similar to NIV in preventing treatment failure among patients with hypercapnic AECOPD, offering a viable alternative with enhanced comfort., Trial Registration: The study was prospectively registered in ClinicalTrials.gov (Identifier: NCT03466385) on March 15, 2018., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Carbapenemase-producing Pseudomonas aeruginosa strains present a specific geographical distribution regarding the type of carbapenemase-encoding genes that they harbor. For more than twenty years, VIM-type enzymes were the only major carbapenemases that were detected among P. aeruginosa isolates in Greece until the emergence of NDM-1-encoding P. aeruginosa in early 2023. In the present study, we present the rapid reversal of the carbapenemase-producing P. aeruginosa epidemiology from bla VIM - to bla NDM -harbouring isolates that occurred in our hospital since then. Between January 2023 and February 2024, 139 isolates tested positive for carbapenemase production with the NG-Test CARBA 5 immunochromatographic assay. Eight isolates were processed with the Hybrispot antimicrobial resistance direct flow chip molecular assay, and the first NDM-producing isolate was further analyzed through whole genome sequencing and bioinformatics analysis. Multiple resistance genes were detected by molecular techniques in accordance with the extensively drug-resistant phenotype. The isolate that was subjected to whole-genome sequencing belonged to the P. aeruginosa high-risk clone ST308, and the bla NDM was located in the chromosome in accordance with previously reported data. During the study period, NDM-producing isolates were increasingly detected, and only five months after their emergence, they overcame VIM producers. Our results indicate the potential of this new clone to spread rapidly and predominate within healthcare institutions, further restricting the already limited treatment options.

Candida auris is an emerging fungal pathogen associated with multi-drug resistance rates and widespread outbreaks in hospitals and healthcare units worldwide. Sequencing studies have revealed that different clonal lineages of the fungus seem to be prevalent among distinct geographical sites. The first case of C. auris in Northern Greece was reported in Thessaloniki in October 2022, almost 2 years after the first isolation in Greece (Athens 2019). The Mycology Laboratory of the Medical School of Aristotle University of Thessaloniki stands as the reference laboratory for fungal diseases in Northern Greece and a meticulous search for the yeast, in plenty of suspicious samples, has been run since 2019 in the Lab as well as a retrospective analysis of all its yeasts' collection, back to 2008, with negative results for the presence of C. auris. Here, are presented the findings concerning the outbreak and surveillance of C. auris in Northern Greece, mainly the region of Thessaloniki and the broader area of Macedonia, from October 2022 until August 2023. The isolates from Northern Greece continue to fall in Clade I and present with an almost equal and stable sensitivity profile until now., (© The Author(s) 2024. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

From 2019 (pre-COVID-19) to 2022 (COVID-19 years), three tertiary Greek hospitals monitored MDRO bloodstream infection (BSI) and hospital acquisition relying on laboratory data. Surveillance covered carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA), in intensive care units (ICUs) and non-ICUs. Non-ICUs experienced significant increases in CRE, CRAB and VRE during the pandemic. In ICUs, CRE increased in 2021, CRAB in 2020 and 2021, and VRE in 2021 and 2022. KPC predominated among CRE. MDRO BSI and hospital acquisition incidence rates increased, driven by CRE and CRAB., (© 2024. The Author(s).)

Ochrobactrum intermedium is recognized as a rare emerging opportunistic pathogen mostly related with bloodstream infections. In this report, we describe the first clinical case of pneumonia due to O. intermedium. The case involved a 71-year old tetraplegic man hospitalized for vertebral fractures after falling from a ladder., Competing Interests: All authors report no conflicts of interest relevant to this article., (© 2024 The Authors.)

NDM carbapenemase-encoding genes disseminate commonly among Enterobacterales through transferable plasmids carrying additional resistance determinants. Apart from the intra-species dissemination, the inter-species exchange of plasmids seems to play an additional important role in the spread of bla NDM . We here present the genetics related to the isolation of three species ( Klebsiella pneumoniae , Proteus mirabilis , and Morganella morganii ) harboring the bla NDM-1 gene from a single patient in Greece. Bacterial identification and antimicrobial susceptibility testing were performed using the Vitek2. Whole genome sequencing and bioinformatic tools were used to identify resistance genes and plasmids. Bla NDM-1 harboring plasmids were found in all three isolates. Moreover, the plasmid constructs of the respective incomplete or circular contigs showed that the bla NDM-1 and its neighboring genes form a cluster that was found in all isolates. Our microbiological findings, together with the patient's history, suggest the in vivo transfer of the bla NDM-1 -containing cluster through three different species in a single patient.

The prompt detection of carbapenemases among Gram-negative bacteria isolated from patients' clinical infection samples and surveillance cultures is important for the implementation of infection control measures. In this context, we evaluated the effectiveness of replacing phenotypic tests for the detection of carbapenemase producers with the immunochromatographic Carbapenem-Resistant K.N.I.V.O. Detection K-Set lateral flow assay (LFA). In total, 178 carbapenem-resistant Enterobacterales and 32 carbapenem-resistant Pseudomonas aeruginosa isolated in our hospital were tested with both our established phenotypic and molecular testing procedures and the LFA. The Kappa coefficient of agreement for Enterobacterales was 0.85 ( p < 0.001) and 0.6 ( p < 0.001) for P. aeruginosa . No major disagreements were observed and notably, in many cases, the LFA detected more carbapenemases than the double meropenem disc test, especially regarding OXA-48 in Enterobacterales and VIM in P. aeruginosa . Overall, the Carbapenem-Resistant K.N.I.V.O. Detection K-Set was very effective and at least equivalent to the standard procedures used in our lab. However, it was much faster as it provided results in 15 min compared to a minimum of 18-24 h for the phenotypic tests.

During the COVID-19 pandemic, different SARS-CoV-2 variants of concern (VOC) with specific characteristics have emerged and spread worldwide. At the same time, clinicians routinely evaluate the results of certain blood tests upon patient admission as well as during hospitalization to assess disease severity and the overall patient status. In the present study, we searched for significant cell blood count and biomarker differences among patients affected with the Alpha, Delta and Omicron VOCs at admission. Data from 330 patients were retrieved regarding age, gender, VOC, cell blood count results (WBC, Neut%, Lymph%, Ig%, PLT), common biomarkers (D-dimers, urea, creatinine, SGOT, SGPT, CRP, IL-6, suPAR), ICU admission and death. Statistical analyses were performed using ANOVA, the Kruskal-Wallis test, two-way ANOVA, Chi-square, T-test, the Mann-Whitney test and logistic regression was performed where appropriate using SPSS v.28 and STATA 14. Age and VOC were significantly associated with hospitalization, whereas significant differences among VOC groups were found for WBC, PLT, Neut%, IL-6, creatinine, CRP, D-dimers and suPAR. Our analyses showed that throughout the current pandemic, not only the SARS-CoV-2 VOCs but also the laboratory parameters that are used to evaluate the patient's status at admission are subject to changes.

Streptococcus pyogenes is responsible for various clinical manifestations in patients of all ages worldwide. Worryingly, an increase in antibiotic resistance rates of S. pyogenes has been observed in many countries. In the present study, 6-year data are presented regarding the antibiotic resistance rates of S. pyogenes in our hospital. During this period, a total of 52 S. pyogenes isolates were recovered from 52 patients and antimicrobial susceptibility testing was performed for 49 isolates. All were susceptible to penicillin, ampicillin, cefotaxime, ceftriaxone, linezolid, moxifloxacin, rifampicin, vancomycin, teicoplanin, and tigecycline. Erythromycin and clindamycin resistance rates were 20.4% and 18.8% respectively. Resistance rates to tetracycline were 40.8%, to chloramphenicol 6.9%, and to levofloxacin 2%. Since macrolides are recommended as an alternative treatment in case of allergy to β-lactams, the high macrolide resistance rates are causing concern. Because different phenotypic antimicrobial patterns for S. pyogenes have been observed in different geographic areas, epidemiological data is of considerable value for the appropriate treatment choices.

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.

SARS-CoV-2 infections may present with various symptoms that are similar to those of other respiratory diseases. For this reason, the need for simultaneous detection of at least RSV and influenza viruses together with SARS-CoV-2 was evident from the early stages of the pandemic. In the present study, we evaluated the clinical performance of the NeuMoDx™ Flu A-B/RSV/SARS-CoV-2 Vantage Assay against the conventional low-plex PCR utilized to detect influenza A-B, RSV, and SARS-CoV-2. There were 115 known positive clinical samples and 35 negative controls obtained from asymptomatic health-care workers included in the study; 25 samples were positive for influenza viruses, 46 for RSV, and 44 for SARS-CoV-2. The sensitivity, specificity, positive predictive value, and negative predictive value of the evaluated method for influenza and SARS-CoV-2 were 100%. The Spearman correlation coefficient was 0.586 (p < 0.05) for influenza and 0.893 (p < 0.05) for SARS-CoV-2. The sensitivity of the aforementioned assay for RSV was 93.47%; the specificity and the positive predictive value were 100%, and the negative predictive value was 92.10%, while the Spearman correlation coefficient was not applicable for the RSV. Overall, the assay under evaluation was shown to be a reliable alternative for the simultaneous detection of influenza viruses, RSV and SARS-CoV-2.

Health care workers are at increased risk of acquiring SARS-CoV-2 infection due to different exposures in the community and in hospital settings. Interventions implemented to avoid nosocomial outbreaks include preventive testing strategies. In this report, we present results from the mass screening program applied in our hospital to all professionals, irrespective of symptoms or risk of exposure. We processed saliva specimens with real-time reverse transcription polymerase chain reaction. The total number of samples received was 43,726. Positive results were 672 and average positivity rate was 1.21%. The average positivity rate was similar to the positivity rate in the community in Greece and EU. More specifically, 80.5% of the positive participants care for patients in their daily activities, 31% experienced no symptoms before receiving the positive result, 46.1% reported a close contact with a patient or infected coworkers and 32.8% reported a close contact with infected family members. We believe that the identification of asymptomatic carriers has proved the effectiveness of the screening program by preventing the putative nosocomial spread of the virus and the depletion of workforce. In conclusion, in times of high incidence in the community, the periodic testing of health care personnel is wise and relevant for implementation costs.

Objectives: In this communication, we describe the emergence of the mcr-1 colistin resistance gene in a blaCTX-M-32 extended-spectrum-β-lactamase-producing Escherichia coli isolate recovered from a pediatric patient in Greece., Methods: Bacterial identification and antimicrobial susceptibility testing were performed with the VITEK2 automated system and broth microdilution. Detection of resistance genes, assignment to sequence type, in silico plasmid detection, and virulence factors were carried out using ResFinder, MLST 2.0, PlasmidFinder 2.1., and VirulenceFinder 2.0, respectively. PlasmidSPAdes v3.11.1 was used to assemble the plasmid contigs. The mcr-1.1-containing plasmid was analyzed for insertion sequence elements using ISfinder. Phylogenetically relevant sequences of the plasmid were identified using the Microbe BLASTN suite., Results: The microorganism was assigned to sequence type 48 and carried four plasmids of different incompatibility groups. The specific mcr-1.1 allele was located in a 32.722 bp plasmid belonging to the IncX4 group with no additional resistance genes., Conclusion: To the best of our knowledge, this is the first detection of mcr-1 in a human specimen in our country. A potential spread of mcr-1 in Greece is concerning because of the existing high rates of carbapenem resistance and colistin usage as a last resort regimen., Competing Interests: Competing interests None declared., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The STANDARD M10 is a novel cartridge-based real time RT-PCR point of care platform that provides significant advantages regarding SARS-CoV-2 detection including fast turnaround times and no need for specialized personnel and facilities. This assay was recently evaluated in our hospital as a rapid alternative to the already present NeuMoDx assay that is used in everyday practice. For this purpose, 30 nasopharyngeal samples by patients admitted to our hospital were used, regardless of clinical suspicion of COVID-19. In our evaluation, the sensitivity of STANDARD M10 was 95%, the specificity was 100%, the positive predictive value was 100%, the negative predictive value was 90% and the kappa coefficient of agreement was 0.927 (p < 0.001)., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

Objectives: To characterize three Salmonella enterica serovar Typhimurium strains using whole genome sequencing (WGS) and conventional methods. The isolates were recovered from three pediatric patients in Greece as part of the hospital's epidemiological surveillance system during 2016 to 2018., Methods: Bacterial identification and antimicrobial susceptibility testing was performed using the VITEK 2 automated system, disc diffusion test, and MIC gradient test while serotyping by the slide agglutination method. Detection of resistance genes, eBurst groups (eBG), assignment to sequence types, single nucleotide polymorphism (SNP) typing, location and characterization of drug resistance regions, and in silico plasmid detection were carried out using WGS., Results: All strains were identified as S. Typhimurium-monophasic, ST34, eBG1 with antigenic formula 1,4, [5], 12:i:-. They were phenotypically resistant to most antibiotics tested except piperacillin/tazobactam, imipenem, and co-trimoxazole. WGS revealed the chromosomally located genes encoding the ASSuT (ampicillin, streptomycin, sulfonamides, and tetracycline) resistant pattern in all three strains. WGS revealed extended spectrum ß-lactamase (ESBL) production in all three strains, the presence of blaCTX-M-3 on an IncI1 plasmid in two strains isolated in 2018, and the chromosomally encoded blaCTX-M-55 plus qnrS1 (resistance to ciprofloxacin) in the strain isolated in 2016. The two strains from 2018 were isolated from the same hospital ward and were genetically related., Conclusions: The emergence of ESBL among S. 1,4,[5], 12:i:- is worrisome due to its increasing antimicrobial resistance phenotype, making clinical treatment difficult. WGS provides an alternative to traditional methods of identification and genomic characterisation of strains, and serves to better understand their epidemiological dynamics and bacterial pathogenesis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)