ESBL-producing <i>Klebsiella pneumoniae</i> gut colonisation and subsequent health-care associated bacteraemia in preterm newborns: a descriptive cohort with nested case–control study

This descriptive and exploratory observational case series examined intestinal colonisation and subsequent bacteraemia due to ESBL-producing <i>Klebsiella pneumoniae</i> (ESBL-<i>Kp</i>) in preterm neonates in Morocco. Prospective bacteriological cultures and antibiotic susceptibility testing were supported by phenotypic methods, including Brilliance ESBL Agar and the NG-Test CARBA-5 assay, for the rapid detection of ESBL and carbapenemase producers. Molecular analysis using PCR was also undertaken to identify specific resistance genes. A total of 567 rectal swabs were collected from 339 preterm neonates, yielding 293 <i>K. pneumoniae</i> isolates. ESBL-producing strains were identified in 53.6% of the neonates (182/339). Detected resistance genes included <i>bla</i>SHV (26.3%), <i>bla</i>CTX-M-1 (42.8%), <i>bla</i>TEM (30.2%), <i>bla</i>OXA-48 (50.0%), <i>bla</i>NDM(15.3%), and <i>bla</i>VIM (4.9%). Principal risk factors for colonisation were low birth weight (OR 1.69), very preterm birth (OR 6.24), enteral tube feeding (OR 2.02), and prolonged use of third-generation cephalosporins (OR 1.26). Among the neonates studied, 32 (9.4%) developed healthcare-associated bacteraemia, with 56.2% of these cases preceded by intestinal colonisation with ESBL-<i>Kp.</i> Clinically, severe respiratory distress and alveolar haemorrhage were strongly associated with increased mortality (aRR = 29.32 and 4.45, respectively). The findings highlight the clinical importance of early screening to guide infection control and antimicrobial stewardship in neonatal intensive care settings.