Epidemiology and antimicrobial resistance patterns of neonatal sepsis in a tertiary NICU in Western Ukraine: a 2023–2025 retrospective surveillance study

Technical Summary: Epidemiology and Antimicrobial Resistance Patterns of Neonatal Sepsis in Western Ukraine (2023–2025)

Problem Statement
Neonatal sepsis remains a primary cause of morbidity and mortality in neonatal intensive care units (NICUs), particularly among preterm and critically ill infants. The clinical management of this condition is increasingly complicated by the rising prevalence of antimicrobial resistance (AMR) among hospital-associated pathogens. While global trends indicate a shift toward multidrug-resistant (MDR) Gram-negative organisms, specific data regarding the epidemiology and resistance patterns of neonatal sepsis in Ukrainian NICUs during the ongoing Russian-Ukrainian war remains scarce. This study addresses the gap in knowledge concerning the etiological spectrum and AMR profiles in a tertiary NICU in Western Ukraine, a region experiencing increased patient flow and healthcare strain despite its distance from active combat zones.

Methodology
The study employed a retrospective observational design, adhering to STROBE guidelines, conducted at the NICU of Chernivtsi Regional Clinical Hospital (a tertiary referral center) between 2023 and 2025.

• Cohort: 61 neonates with a clinical diagnosis of neonatal sepsis were included. Inclusion required a clinical diagnosis, availability of microbiological data, and NICU hospitalization.
• Specimens: Microbiological evaluation included 61 blood cultures, 61 cerebrospinal fluid (CSF) samples, and 98 endotracheal aspirates (collected from mechanically ventilated neonates, with standardized collection beginning in 2024).
• Laboratory Analysis: Samples were processed using standard culture-based methods. Antimicrobial susceptibility testing (AST) was performed via the Kirby–Bauer disk diffusion method, interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines.
• Definitions: Multidrug resistance (MDR) was defined as non-susceptibility to at least one agent in three or more antimicrobial classes. ESKAPE pathogens were analyzed as markers of healthcare-associated resistance.
• Statistical Approach: The study was primarily descriptive and hypothesis-generating. Continuous variables were reported as mean ± standard deviation, and categorical variables as frequencies and percentages. No formal sample size calculation or power analysis was performed.

Key Results

• Etiological Profile: Positive blood cultures were identified in 72.1% (44/61) of cases. Gram-positive organisms predominated (71.5%), primarily coagulase-negative staphylococci (CoNS), with Staphylococcus haemolyticus (43.2%) and Staphylococcus epidermidis (13.4%) being the most frequent. Gram-negative pathogens accounted for 31.3% of isolates, showing a temporal increase in Klebsiella aerogenes, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa.
• Site-Specific Findings:
  • CSF: 55.7% of cultures were positive, with S. haemolyticus as the most common isolate. Klebsiella species were the primary Gram-negative pathogens in CSF.
  • Endotracheal Aspirates: 90.4% of samples from ventilated neonates were culture-positive. Gram-negative organisms predominated (64.1%), driven by P. aeruginosa and Klebsiella spp.
• Mortality: Eight fatal cases were recorded. All fatalities were associated with Gram-negative organisms, most frequently ESBL-producing K. aerogenes and K. pneumoniae. MDR ESKAPE pathogens were identified in 50% of fatal cases.
• Antimicrobial Resistance Patterns:
  • Gram-Negative: High resistance rates were observed against cephalosporins, aminoglycosides, and carbapenems. K. aerogenes showed resistance to cefotaxime (84.0%), cefepime (83.5%), and linezolid (93.3%). A. baumannii demonstrated 100% resistance to cefepime. P. aeruginosa showed 100% resistance to ampicillin, clindamycin, and linezolid.
  • Gram-Positive: S. epidermidis was fully resistant to cefepime. Enterococcus faecalis exhibited high resistance to meropenem (91.6%) and complete resistance to tobramycin. Methicillin-resistant staphylococcal isolates were detected in 2025.
• Contextual Trends: National statistical data indicated a rise in the proportion of infant deaths attributed to neonatal sepsis, increasing from 10.0% in 2023 to 27.3% in 2025, coinciding with the observed increase in Gram-negative and MDR isolates within the NICU cohort.

Significance and Claims
The authors assert that this study provides a critical, descriptive snapshot of the evolving microbiological landscape in a tertiary Ukrainian NICU during a period of systemic healthcare stress. The findings highlight a dual burden: the persistent dominance of CoNS (specifically S. haemolyticus) as causes of late-onset sepsis, coupled with a concerning shift toward MDR Gram-negative ESKAPE pathogens.

The paper emphasizes that the high resistance rates to commonly used and reserve antibiotics (including carbapenems and glycopeptides) substantially limit the effectiveness of empirical therapeutic regimens. Consequently, the authors conclude that continuous local microbiological surveillance and institution-specific antimicrobial stewardship strategies are essential. They argue that empirical protocols must be regularly updated based on current local data to optimize outcomes and minimize selection pressure.

Limitations
The authors explicitly note that the study is limited by its retrospective, single-center design and relatively small sample size, which restricts generalizability. The lack of standardized severity scores and incomplete clinical stratification prevented adjustment for potential confounders. Therefore, the authors characterize the study as hypothesis-generating rather than definitive, calling for future prospective multicenter studies to validate these trends.