Transmission of ST45 and ST2407 extended-spectrum ß-lactamase-producing Klebsiella pneumoniae in neonatal intensive care units, associated with contaminated environments.

OBJECTIVES: Given the increasing frequency of infections due to extended-spectrum ß-lactamase (EBSL)-producing Klebsiella pneumoniae in humans over recent decades, infection control against this pathogen is of high importance. METHODS: In this study, the transmission mode of ESBL-producing K. pneumoniae in neonatal intensive care units (NICU) was investigated. We collected K. pneumoniae isolates from patients admitted to the NICU and performed environmental screening of the NICU and nearby obstetrics department. All isolates were analysed using antimicrobial susceptibility testing, whole-genome sequencing, molecular typing, and antimicrobial and virulence determinant screening. The phylogenetic relationships of all the isolates were analysed using core-genome multi-locus sequence type and single-nucleotide polymorphism-based analysis, and their plasmids harbouring antimicrobial resistance genes in ST2407 were compared. RESULTS: Eighteen K. pneumoniae isolates were collected, of which 10 isolates from patients belonged to ST45 and ST2407, and eight isolates from the environment belonged to various other clones. Although 80% and 100% of isolates from patients were ESBL-positive (blaCTX-M-14 and blaCTX-M-55) and possessed siderophores, respectively; fewer environmental isolates harboured antimicrobial resistance and virulence genes. For both ST45 and ST2407 isolates, the phylogenetic assessment revealed a close relationship between clinical and environmental isolates, indicating that bloodstream infections were associated with the contaminated environments. CONCLUSIONS: Based on these results, the environmental prevalence of K. pneumoniae should be considered given its pathogenicity in humans. Early and active infection control measures could decrease the spread of multidrug-resistant K. pneumoniae.

Gut bacteria and late-onset neonatal bloodstream infections in preterm infants.

Late-onset neonatal bloodstream infections remain challenges in neonatology. Hand hygiene, line care, and judicious use of indwelling lines are welcome interventions, but might not reduce the incidence of late-onset neonatal bloodstream infections from bacteria originating in the gut. Accumulating data suggest that many pathogens causing late-onset neonatal bloodstream infections are of gut origin, including Gram-positive cocci. In addition to the host-canonical paradigm (i.e., all bacteria have equal risk of invasion and bloodstream infections are functions of variable infant susceptibility), we should now consider bacteria-canonical paradigms, whereby late-onset neonatal bloodstream infection is a function of colonization with a specific subset of bacteria with exceptional invasive potential. In either event, we can no longer be content to reactively approach late-onset neonatal bloodstream infections; instead we need to reduce the occurrences of these infections by broadening our scope of effort beyond line care, and determine the pre-invasive habitat of these pathogens.