Klebsiella pneumoniae

Ni-Urease#

Urease supports intestinal colonization and gastrointestinal stress resistance, enabling survival through the acidic stomach to establish gut reservoirs.^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓} Host Calprotectin (S100A8/A9) (S100A8/A9) sequesters nickel from K. pneumoniae, directly inhibiting urease activity—a key Nutritional Immunity (Metal Sequestration) mechanism.

In the preterm gut, Klebsiella is a major NEC-associated pathogen. Dietary nickel from infant formula (especially soy-based, ~10x higher nickel (Ni) than cow's milk) fuels urease, raising gut pH and promoting Proteobacteria bloom at the expense of acid-producing commensals like Lactobacillus.^{[2]Nickel as a Catalytic Driver of Necrotizing Enterocolitis: Dietary Nickel, Microbial Metallomics, and the Activation of Nickel-Dependent Virulence Pathways in the Preterm GutKaren Pendergrass · 2026Open reference 2 ↓}

Ni-Glyoxalase I#

Predicted to possess nickel (Ni)-dependent Glyoxalase I (GloI) based on genome analysis across all Enterobacteriaceae.^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓} GloI detoxifies methylglyoxal, a toxic glycolysis byproduct, enabling sustained growth during infection. The nickel-vs-zinc (Zn) selectivity difference between pathogen GloI and human GloI creates a potential selective drug target.

Yersiniabactin#

Produces yersiniabactin (Ybt), originally characterized in Yersinia pestis but horizontally acquired by hypervirulent K. pneumoniae strains.^{[3]Infection metallomics for critical care in the post-COVID eraPatil RH, Luptakova D, Havlicek V · 2021Open reference 3 ↓}

Ybt is a true dual-function metallophore: binds iron(III) (Fe3+) for classical iron acquisition and also chelates extracellular nickel, feeding nickel (Ni)-dependent enzymes.^{[1]Role of Nickel in Microbial PathogenesisRobert J. Maier, Stéphane L. Benoit · 2019Open reference 1 ↓}

Ybt-copper (Cu) complexes help resist copper toxicity in the urinary tract (paralleling UPEC). Ybt detection in urine is a potential diagnostic biomarker for invasive Klebsiella UTI.

Other Siderophores#

Also produces enterobactin and aerobactin for iron scavenging. Hypervirulent strains often carry additional siderophore gene clusters, correlating with invasive disease capacity.

Clinical Significance#

Urinary tract infections: a leading cause of hospital-acquired UTI, especially catheter-associated. Pneumonia: classical "Friedlander's pneumonia" with necrotizing lung destruction.

Neonatal sepsis and NEC: major pathogen in preterm infants; urease-driven pH shift contributes to Dysbiosis and intestinal barrier breakdown.^{[2]Nickel as a Catalytic Driver of Necrotizing Enterocolitis: Dietary Nickel, Microbial Metallomics, and the Activation of Nickel-Dependent Virulence Pathways in the Preterm GutKaren Pendergrass · 2026Open reference 2 ↓}

A Klebsiella pneumoniae-like OTU was detected in 11 of 12 NEC cases during week 1 of life in prospective preterm cohorts, corroborating earlier reports of gammaproteobacteria blooms 1-3 days before late-onset NEC.^{[4]Zhou 2015 — Premature Infant Microbiome Prior to NECZhou Y, Shan G, Sodergren E et al. · 2015Open reference 4 ↓[5]Torrazza 2013 — Intestinal Microbial Ecology and Environmental Factors Affecting NECTorrazza RM, Ukhanova M, Wang X et al. · 2013Open reference 5 ↓[6]Devarajalu 2025 — Gut microbiota signatures in Indian preterm infants with NEC: shotgun metagenomic approachPrabavathi Devarajalu, Savita Verma Attri, Jogender Kumar et al. · 2025Open reference 6 ↓}

LPS and gut translocation in COVID-19 / Long COVID: Enterobacteriaceae including K. pneumoniae translocate from the gut during severe COVID-19 and contribute to secondary bacteremia and post-acute sequelae.^{[7]Bernard-Raichon et al. 2022 — Gut microbiome dysbiosis in antibiotic-treated COVID-19 patients is associated with microbial translocation and bacteremiaLucie Bernard-Raichon, Mericien Venzon, Jon Klein et al. · 2022Open reference 7 ↓[8]Li et al 2024 — The Causal Role of Gut Microbiota in Susceptibility of Long COVID: A Mendelian Randomization StudyZuming Li, Qinghua Xia, Jieni Feng et al. · 2024Open reference 8 ↓[9]Rego & Araújo-Filho 2024 — The Impact of Gut Microbiota on Long COVID: Insights and ChallengesAmália Cinthia Meneses do Rêgo, Irami Araújo-Filho · 2024Open reference 9 ↓}

Antibiotic resistance: carbapenem-resistant K. pneumoniae (CRKP) is a WHO Critical Priority pathogen. Metal resistance genes frequently co-locate with antibiotic resistance genes on mobile genetic elements, driving co-selection under environmental metal pressure.^{[10]Understanding the Development of Environmental Resistance Among Microbes: A ReviewSrivastava J, Chandra H, Singh N et al. · 2016Open reference 10 ↓}

Zinc ionophores such as PBT2 can resensitize carbapenem-resistant K. pneumoniae to tigecycline.^{[11]Wang 2025 — Disruption of Zinc Homeostasis Reverses Tigecycline Resistance in Klebsiella pneumoniaeJinyu Wang, Cuiping Xia, Zhaoxin Xia et al. · 2025Open reference 11 ↓}

Liver abscess: hypervirulent strains (hvKp) cause pyogenic liver abscess, particularly in East Asia.

Preterm brain injury: Klebsiella-dominated gut dysbiosis in preterm infants correlates with altered white matter development via the gut-brain axis.^{[12]Wang 2023 — Microbial Gut-Brain Axis and White Matter Injury in Preterm InfantsWang J, et al. · 2023Open reference 12 ↓}