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. 2022 Jan 1;74(1):e1-e7.
doi: 10.1097/MPG.0000000000003299.

Toxin-Producing Klebsiella oxytoca in Healthy Infants: Commensal or Pathobiont?

Theresa M Greimel  1 , Laura Stampfer  1 , Eva Leitner  2 , Sabine Kienesberger  3   4   5 , Ellen L Zechner  3   4   5 , Michael Bozic  2 , Gabriel E Wagner  2 , Katrin Unterhauser  3 , Maksym Kitsera  3 , Almuthe C Hauer  1 , Gregor Gorkiewicz  6   4 , Philipp Wurm  6 , Francesco Valitutti  7 , Christoph Högenauer  8   4 , Karl Martin Hoffmann  1   9
Affiliations

Toxin-Producing Klebsiella oxytoca in Healthy Infants: Commensal or Pathobiont?

Theresa M Greimel et al. J Pediatr Gastroenterol Nutr. .

Abstract

Objectives: Klebsiella oxytoca is a gastrointestinal pathobiont with the potential to produce the toxins tilivalline and tilimycin, which cause antibiotic-associated hemorrhagic colitis. Overgrowth of toxigenic K oxytoca has recently been implicated in necrotizing enterocolitis. K oxytoca colonizes 2-9% of healthy adults, however, there is no systematic data on colonization in healthy children. We investigated K oxytoca colonization and its toxigenic properties in healthy infants.

Methods: We sampled stool of healthy infants and determined K oxytoca colonization using stool culture and PCR (pehX). Toxin in stool was measured with HPLC/high-resolution mass spectrometry. K oxytoca isolates were typed using multi-locus sequence typing (MLST) and K oxytoca toxin PCR (npsA/B). Cytotoxin production of isolates was analyzed by MTT assay.

Results: K oxytoca was detected in 30 of 61 infants (49%) using stool culture and in 45 of 61 (73%) using PCR (pehX). Toxin marker PCR (npsA/B) was positive in 66% of stool samples positive for K oxytoca PCR. Stool toxin levels were too low for quantitation but traces of tilivalline were detected. Contrarily, 49% of K oxytoca isolates demonstrated toxicity in the MTT assay. MLST revealed 36 distinct sequence types affiliated with all known K oxytoca sequence type clusters (A, B1 and B2).

Conclusions: More than 70% of healthy infants were colonized with K oxytoca. Toxin quantities in stool of colonized healthy infants were below detection level, yet half of the isolates produced toxin in vitro demonstrating their pathobiont potential. The high occurrence of toxigenic K oxytoca in healthy infants has to be considered for future disease association studies.

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Conflict of interest statement

The authors report no conflicts of interest.

References

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