Carbapenem-Resistant Klebsiella pneumoniae in Romania and South-Eastern Europe: A Multilingual Narrative Review of Pandemic-Era Trajectories, 2020–2025

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is the pathogen driving the deterioration of the European antimicrobial resistance landscape, and the burden falls disproportionately on Romania and South-Eastern Europe. The objective of this review was to synthesise evidence published between 2020 and 2025 on the epidemiology, molecular characteristics, clinical impact, and pandemic-era trajectory of CRKP healthcare-associated infections across South-Eastern Europe, including Romania. This retrospective, qualitative narrative review combined the international literature with a deliberately multilingual search of national-language sources in Romanian, Bulgarian, Greek, Croatian, Slovenian, and Serbian, including congress abstract books, doctoral theses, national reference-laboratory reports, and agency surveillance series that are absent from PubMed. Three findings emerge. First, the region is not epidemiologically uniform: estimated incidence of carbapenem-resistant K. pneumoniae bloodstream infection in 2024 ranged from 0.62 per 100,000 population in Slovenia to 20.31 in Romania, against a European Union/European Economic Area (EU/EEA) figure of 3.46, and the steepest relative rise between 2019 and 2024 was recorded in Bulgaria (+374.1%). Second, a distinctive molecular signature has consolidated in the northern half of the region: co-production of a metallo-β-lactamase with an OXA-48-like enzyme (OXA-48, a class D, oxacillinase-type carbapenemase), reported in 44.4–61.2% of characterised Romanian isolates across independent centres, which removes ceftazidime-avibactam from the therapeutic repertoire and leaves aztreonam-avibactam and cefiderocol as the principal remaining options. Third, the pandemic did not produce a single regional signal but a consistent sequence—a transient interruption of upward trends during 2020, a marked acceleration from 2021, and persistence of the elevated level after 2022—with national-language surveillance from Croatia and Slovenia showing that the direction of the apparent pandemic effect depends on whether incidence or resistance proportion is measured. The national-language literature adds granularity unavailable in English, but the evidence base remains structurally uneven: Albania, Kosovo, and North Macedonia contribute almost no primary data, and no country in the region has published a CRKP-attributable mortality estimate for the review period. CRKP in Romania and South-Eastern Europe now maps onto three molecular zones—OXA-48 predominance in the Western Balkans and Croatia, a KPC-to-metallo-β-lactamase transition in Greece, and metallo-β-lactamase plus OXA-48-like co-production in Romania and increasingly Bulgaria—that require different empirical therapy; the COVID-19 pandemic did not create this burden but accelerated and entrenched it, and closing the region’s mortality-data and Western Balkan surveillance gaps should be a priority for future research.