Gram-negative bacteria (GNB) are a major cause of neonatal sepsis in low- and middle-income countries (LMICs). Although the World Health Organization (WHO) reports that over 80% of these sepsis deaths could be prevented through improved treatment, the efficacy of the currently recommended first- and second-line treatment regimens for this condition is increasingly affected by high rates of drug resistance. Here we assess three well known antibiotics, fosfomycin, flomoxef and amikacin, in combination as potential antibiotic treatment regimens by investigating the drug resistance and genetic profiles of commonly isolated GNB causing neonatal sepsis in LMICs. The five most prevalent bacterial isolates in the NeoOBS study (NCT03721302) are Klebsiella pneumoniae, Acinetobacter baumannii, E. coli, Serratia marcescens and Enterobacter cloacae complex. Among these isolates, high levels of ESBL and carbapenemase encoding genes are detected along with resistance to ampicillin, gentamicin and cefotaxime, the current WHO recommended empiric regimens. The three new combinations show excellent in vitro activity against ESBL-producing K. pneumoniae and E. coli isolates. Our data should further inform and support the clinical evaluation of these three antibiotic combinations for the treatment of neonatal sepsis in areas with high rates of multidrug-resistant Gram-negative bacteria.

Introduction: The epidemiology of candidemia has shifted in the past few decades; drug-resistant non-albicans Candida species have become more prevalent worldwide. The aim of this retrospective study was to determine the epidemiology of Candida species isolated from hospitalized neonates, children and adults, and to investigate a potential changing susceptibility pattern in a large general tertiary hospital. Methods: All unique Candida strains isolated from candidemia cases between 1 January 2020 and 15 October 2024 were identified, and their susceptibility profile was characterized. The distribution pattern in different ward types (medical, surgical, pediatric and ICU) was recorded. Cumulative annual susceptibility profiles were compared. Results: Candidemia incidence increased during the COVID-19 pandemic, from 0.63/1000 patient-days in 2020 to 0.96/1000 patient-days in 2022, and has since slightly decreased (0.83 and 0.89 in 2023 and 2024, respectively). Candidemia-associated mortality was high (>50%) in 2020 and peaked during the pandemic. During the study period, Candida parapsilosis remained the most frequent Candida spp. However, since the first isolation of Candida auris from the bloodstream in late 2022, and despite intense infection control measures taken, its frequency sharply climbed to the second position after only C. parapsilosis in the first 10 months of 2024 (33.6% vs. 25.2% for C. parapsilosis and 21.0% for C. albicans). While C. albicans has remained highly susceptible to fluconazole (1% resistance rate), C. parapsilosis manifested significant resistance to fluconazole during 2022–2024 (52%). C. auris was universally resistant to azoles and one isolate also resistant to echinocandins. Conclusions: A high prevalence of azole resistance of C. parapsilosis, the most frequently isolated Candida species, persists, and a significant rise of C. auris was recorded in nosocomial bloodstream infections with severe implications on public health.

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a serious public health issue. The study aimed to identify the antimicrobial resistance and accessory genes, the clonal relatedness, and the evolutionary dynamics of selected CRKP isolates recovered in an adult and pediatric intensive care unit of a tertiary hospital in Greece. Methods: Twenty-four CRKP isolates recovered during 2018–2022 were included in the study. Next-generation sequencing was performed using the Ion Torrent PGM Platform. The identification of the plasmid content, MLST, and antimicrobial resistance genes, as well as the comparison of multiple genome alignments and the identification of core genome single-nucleotide polymorphism sites, were performed using various bioinformatics software. Results: The isolates belonged to eight sequence types: 11, 15, 30, 35, 39, 307, 323, and 512. A variety of carbapenemases (KPC, VIM, NDM, and OXA-48) and resistance genes were detected. CRKP strains shared visually common genomic regions with the reference strain (NTUH-K2044). ST15, ST323, ST39, and ST11 CRKP isolates presented on average 17, 6, 16, and 866 recombined SNPs, respectively. All isolates belonging to ST15, ST323, and ST39 were classified into distinct phylogenetic branches, while ST11 isolates were assigned to a two-subclade branch. For large CRKP sets, the phylogeny seems to change approximately every seven SNPs. Conclusions: The current study provides insight into the genetic characterization of CRKP isolates in the ICUs of a tertiary hospital. Our results indicate clonal dispersion of ST15, ST323, and ST39 and highly diverged ST11 isolates.

Background: Multi/extensively drug-resistant bacterial infections have recently increased and new antimicrobial options are needed for difficult-to-treat infections. Ceftazidime/avibactam (CZA) has been approved for patients 3 months to 18 years of age, but real-life data on its off-label use in neonates and young infants are still scarce. Materials: : We report demographic, clinical and microbiologic data as well as outcome and safety of all cases of infants treated with CZA between January 1, 2021 and September 30, 2022 in a tertiary neonatal intensive care unit. We also review all neonatal cases previously reported. Results: Twenty-one patients [17 males, with median gestational age 29⁺² (IQR 6⁺⁶) weeks] received 31 CZA courses at a dose of 20–50 mg/kg/dose of ceftazidime q8h for suspected or proved multi/extensively drug-resistant infections. Median postnatal age at the onset of treatment was 44 days (IQR: 94 days). Twelve bacteremias, 2 urinary tract infections and 1 ventilator-acquired pneumonia were recorded. Twelve (39%) treatments were targeted, while 19 (61%) were empirically started due to known colonization with Klebsiella pneumoniae carbapenemase-producing Gram-negative bacteria. All patients had received multiple antibiotics prior and concomitantly with CZA. The most common pathogen identified at targeted administrations was carbapenem-resistant Klebsiella pneumoniae (83%). No serious adverse events attributed to the drug were detected. Twenty-one courses of CZA administration to 20 neonates with a median gestational age of 28.5 (IQR 3.5) weeks were previously reported without significant related adverse events. Conclusions: Favorable clinical and microbiologic responses in neonatal intensive care unit patients treated with CZA off-label were observed without significant and unexpected adverse events in critically ill neonates.

Background: Although ceftazidime/avibactam (CAZ/AVI) has become an important option for treating adults and children, no data or recommendations exist for neonates. We report a neonatal sepsis case due to CAZ/AVI-resistant bla_KPC-2-harboring Klebsiella pneumoniae carrying bla_VEB-25 and the use of a customized active surveillance program in conjunction with enhanced infection control measures. Methods: The index case was an extremely premature neonate hospitalized for 110 days that had been previously treated with multiple antibiotics. Customized molecular surveillance was implemented at hospital level and enhanced infection control measures were taken for early recognition and prevention of outbreak. Detection and identification of bla_VEB-25 was performed using next-generation sequencing. Results: This was the first case of a bloodstream infection caused by KPC-producing K. pneumoniae that was resistant to CAZ/AVI without the presence of a metalo-β-lactamase in the multiplex PCR platform in a neonate. All 36 additional patients tested (12 in the same NICU and 24 from other hospital departments) carried wild-type bla_VEB-1 but they did not harbor bla_VEB-25. Conclusion: The emergence of bla_VEB-25 is signal for the horizontal transfer of plasmids at hospital facilities and it is of greatest concern for maintaining a sharp vigilance for the surveillance of novel resistance mechanisms. Molecular diagnostics can guide appropriate antimicrobial therapy and the early implementation of infection control measures against antimicrobial resistance.

Background: Leclercia adecarboxylata is a Gram-negative bacillus that can rarely cause infections in humans. We recently treated a case of peritonitis due to L. adecarboxylata in a peritoneal dialysis (PD) pediatric patient, and we systematically reviewed all the relevant reported cases in the literature. Methods: We searched the PubMed and Scopus databases, and we reviewed 13 such cases (2 children, 11 adults) that were reported, including our patient. Results: The mean (±SE) age was 53.2 ± 22.5 years, with a male-to-female ratio of approximately 1:1.6. Their mean vintage period on PD prior to L. adecarboxylata peritonitis was 37.5 ± 25.3 months. The VITEK card was the identification diagnostic tool in most cases (63%). The antimicrobial agent that was most frequently used was ceftazidime, which was implemented in 50% of cases as initial therapy, either as a monotherapy or combination therapy; in only two patients (15.3%) was the Tenkhoff catheter removed. The median duration of treatment was 18 days (range of 10–21 days), and all 13 patients that were reviewed were healed. Conclusions: Physicians should be aware that L. adecarboxylata is noted to rarely cause peritonitis in PD patients; however, this pathogen seems to be sensitive to most antimicrobial agents and can result in a favorable outcome with the selection of appropriate treatment.