Emergence of a novel hypervirulent extensively drug-resistant ST383 Klebsiella pneumoniae lineage carrying ICEKp5 in Lebanon

This study reports the emergence in Lebanon of a novel, monophyletic ST383 *Klebsiella pneumoniae* lineage that uniquely combines extensive drug resistance (carrying *bla*OXA-48, *bla*NDM-5, and *bla*CTX-M variants) with a full spectrum of hypervirulence factors acquired via ICEKp5, marking a concerning convergence of high-risk traits distinct from previously known local clones.

The Gist

The Story: A "Super-Bug" Upgrade in Lebanon

Imagine the bacteria Klebsiella pneumoniae as a notorious criminal gang. For a long time, this gang has been known for two things:

1. Being tough to kill: They wear heavy armor (antibiotic resistance) that makes standard police weapons (antibiotics) useless.
2. Being sneaky: They have special tools (virulence factors) that help them break into houses (human bodies) and cause damage.

Usually, these two traits are found in different gangs. Some are tough but weak; others are sneaky but easy to defeat. But recently, a new, terrifying version of this gang has emerged in Lebanon. They have combined both traits into one super-criminal.

The Main Characters: The "ST383" Gang

The specific gang involved here is called ST383. Think of ST383 as a specific family name or a specific criminal organization. They are already known to be dangerous in the Middle East because they carry heavy armor (resistance to carbapenem antibiotics, which are usually the "last resort" drugs).

However, the Lebanese hospitals had been dealing with a "standard" version of this gang. They were tough, but they weren't the most aggressive attackers.

The New Threat: The "Convergent" Upgrade

The researchers discovered a new, upgraded version of the ST383 gang in Lebanon. They call this a "Convergent" strain.

• The Old Gang: Had heavy armor (resistance) but lacked the ultimate weapons.
• The New Gang: Has the heavy armor PLUS a full arsenal of super-weapons.

This new gang is what scientists call hv-XDR:

• hv (Hypervirulent): They are incredibly aggressive and can cause severe disease very quickly.
• XDR (Extensively Drug-Resistant): They are resistant to almost every antibiotic we have.

How Did They Get So Powerful? (The "Loot" Analogy)

Bacteria get stronger by picking up "loot" from other bacteria. Think of this like a video game character finding new gear. This new Lebanese gang found two specific pieces of loot that made them unstoppable:

1. The "ICEKp5" Backpack (The Yersiniabactin Locus):
   Imagine a backpack that allows the bacteria to steal iron from the human body. Iron is like fuel for the bacteria; without it, they starve. This new backpack (called ICEKp5) is a high-tech iron-stealing device. The old Lebanese gang didn't have this backpack. The new one does, making them much better at surviving inside a human.

2. The "Hybrid Plasmid" (The Resistance & Virulence Truck):
   Bacteria carry their DNA on little trucks called plasmids. This new gang has a massive hybrid truck that carries:

   • More Armor: Genes that resist the strongest antibiotics (NDM-5 and OXA-48).
   • More Weapons: Genes that make them sticky and hard to remove (aerobactin) and genes that change their shape to look like a slippery slime (rmpA/rmpA2), helping them hide from the immune system.

The Investigation: Where Did They Come From?

The researchers used a "genetic fingerprint" (DNA sequencing) to figure out who these criminals were.

• The Old Lebanese Gang: They were related to other local gangs, but they were missing the "Iron Backpack" (ICEKp5).
• The New Lebanese Gang: They are not related to the old local gang. In fact, they are genetically very different (like cousins who haven't seen each other in years).
• The Real Connection: The new Lebanese gang is almost identical to a gang recently spotted in Egypt.

The Metaphor: Imagine the old Lebanese gang was a local street gang. The new gang didn't evolve from the locals; it was a new crew that crossed the border from Egypt. They brought their heavy armor and their new super-weapons with them, and now they are causing trouble in Lebanon.

Why Should We Care?

This is a "perfect storm" scenario.

1. They are everywhere: They are spreading across the Eastern Mediterranean (Egypt, Lebanon, Qatar).
2. They are untouchable: We have very few drugs left that can kill them.
3. They are deadly: Because they have the "Iron Backpack" and the "Slime Shield," they can cause severe infections (like pneumonia or bloodstream infections) that are very hard to treat.

The Bottom Line

This paper is a warning sign. It tells us that a new, highly dangerous version of a bacteria has arrived in Lebanon. It's not just a local problem; it's part of a regional trend where bacteria are swapping DNA to become both super-resistant and super-deadly.

The scientists are saying: "We need to watch the borders, check our hospitals carefully, and stop these super-bugs from spreading before they become a global nightmare."

Technical Summary

1. Problem Statement

The global emergence of Klebsiella pneumoniae strains that combine hypervirulence (hv) and carbapenem resistance (CR) poses a critical public health threat. These "convergent" strains (CR-hvKp) are difficult to treat due to multidrug resistance and capable of causing severe, invasive infections in healthy individuals.

• Specific Context: The ST383 lineage is a known high-risk clone prevalent in the Eastern Mediterranean Region (EMR), particularly in Lebanon, Egypt, and Qatar.
• Knowledge Gap: While ST383 was previously identified in Lebanon as a carbapenem-resistant clone carrying bla_NDM-5 and bla_OXA-48, its hypervirulence potential was not fully characterized. Previous Lebanese isolates lacked key virulence determinants like the yersiniabactin locus. There was a need to determine if a new, more dangerous sub-lineage had emerged in Lebanon that combined extensive drug resistance (XDR) with full hypervirulence.

2. Methodology

The study employed a comprehensive genomic epidemiology approach:

• Sample Collection: Three non-duplicate clinical isolates (LBN_CAKp91, LBN_CTKp3, LBN_CTKp11) were collected from the American University of Beirut Medical Center in 2025.
• Phenotypic Characterization:
  • Identification via MALDI-TOF MS.
  • Antimicrobial susceptibility testing (AST) via E-test and disk diffusion (Kirby-Bauer) against a broad panel of antibiotics.
  • Carbapenemase detection using NG-Test CARBA-5.
• Genomic Analysis:
  • Sequencing: Whole-genome sequencing (WGS) using Illumina MiSeq (2×250 bp).
  • Assembly & Annotation: De novo assembly (SPAdes) and annotation (Bakta).
  • Resistance & Virulence Profiling: Used Kleborate (v3.2.4), ABRicate (against VFDB), and AMRFinderPlus to identify resistance genes, virulence factors (including capsule regulators, siderophores), and plasmid replicons.
  • Plasmid Analysis: Identified via PlasmidFinder and MOB-suite; structural analysis of resistance and virulence loci.
  • Phylogenetics: Core genome SNP analysis using Snippy and kSNP3 to construct a parsimony tree. The study isolates were compared against regional ST383 strains from Egypt, Qatar, Italy, and previous Lebanese isolates.
  • Mobile Genetic Elements: Specific analysis of Integrative and Conjugative Elements (ICEs) and the genetic environment of carbapenemase genes (bla_NDM, bla_OXA-48).

3. Key Contributions

• Discovery of a Novel Lineage: Identification of a distinct, monophyletic ST383 sub-lineage in Lebanon that is phylogenetically separate from previously reported Lebanese ST383 clones (>164 SNPs difference).
• First Report of Full Convergence in Lebanese ST383: This is the first documentation of an ST383 strain in Lebanon harboring the complete spectrum of hypervirulence determinants alongside XDR mechanisms.
• ICEKp5 Characterization: Detailed characterization of the acquisition of ICEKp5 (carrying the yersiniabactin locus ybt14) as the defining feature of this new lineage, distinguishing it from earlier Lebanese clones and other regional strains.
• Regional Epidemiology: Established a strong phylogenetic link between these Lebanese isolates and Egyptian strains (specifically EGY_DAPDKI01.1), suggesting cross-border dissemination within the EMR.

4. Key Results

A. Phylogenetic Relationships

• The three study isolates formed a tight cluster with only 3–9 SNPs difference between them.
• They are most closely related to an Egyptian strain (EGY_DAPDKI01.1) with 59–65 SNPs difference.
• They are phylogenetically distinct from the previously reported Lebanese ST383 clone (Sobh et al., 2024), showing 164–220 SNPs divergence, indicating an independent introduction event rather than local microevolution.

B. Resistance Profile (XDR)

• Phenotype: All three isolates were classified as Extensively Drug-Resistant (XDR), resistant to all tested antibiotics except colistin (and tigecycline for one isolate).
• Genotype: They share a conserved resistome with previous Lebanese ST383 isolates, carrying:
  • Carbapenemases: bla_NDM-5 and bla_OXA-48.
  • ESBLs: bla_CTX-M-15 and bla_CTX-M-14b.
  • Plasmids: An IncL plasmid (carrying bla_CTX-M-14b and bla_OXA-48) and a hybrid IncHI1B/IncFIB plasmid (carrying bla_NDM-5 and bla_CTX-M-15).
• Conservation: The genetic environments of bla_NDM-5 and bla_OXA-48 were highly conserved across geographically diverse ST383 isolates, suggesting common plasmid origins.

C. Virulence Profile (Hypervirulence)

• Complete Virulence Repertoire: Unlike previous Lebanese ST383 isolates (which lacked yersiniabactin and peg-344), these new isolates possess the full complement of hypervirulence factors:
  • Capsule Regulators: rmpA and rmpA2.
  • Siderophores: Complete aerobactin (iucABCD, iutA) on the hybrid plasmid and complete yersiniabactin (ybtAEPQSTUX) on ICEKp5.
  • Biomarker: peg-344.
• Virulence Score: These isolates achieved a Kleborate virulence score of 4, the highest possible score for K. pneumoniae, classifying them as convergent hv-XDR strains.
• ICEKp5: The isolates carry ICEKp5 integrated at the chromosomal tRNA-Asn site. This element contains the intact yersiniabactin biosynthesis/transport locus (ybt14 lineage) and a functional Type IV Secretion System (T4SS), enabling conjugative transfer.

D. Structural Analysis

• The hybrid IncHI1B/IncFIB plasmid in these isolates carries the aerobactin operon, rmpA/rmpA2, and the tellurite resistance operon (terZABCDW).
• The yersiniabactin locus on ICEKp5 is intact and conserved among Lebanese and specific Egyptian strains (sharing YbST 151-1LV), supporting a single acquisition event from a common ancestor.

5. Significance and Implications

• Clinical Threat: The convergence of ICEKp5-mediated yersiniabactin production with the existing XDR plasmid backbone creates a "perfect storm" pathogen. These strains are resistant to almost all antibiotics and possess enhanced iron acquisition and mucoidy capabilities, likely leading to increased severity of infections (e.g., sepsis, pneumonia) and transmission potential.
• Epidemiological Shift: The findings indicate that ST383 in Lebanon is not merely a locally expanding clone but is subject to regional dissemination. The close genetic relationship with Egyptian strains suggests cross-border transmission via healthcare travel or patient transfer within the EMR.
• Evolutionary Mechanism: The study highlights the stepwise evolution of ST383:
  1. Acquisition of an IncL plasmid (bla_OXA-48).
  2. Acquisition of a large hybrid IncHI1B/IncFIB plasmid (bla_NDM, aerobactin).
  3. Recent acquisition of ICEKp5 (yersiniabactin), transforming a resistant clone into a fully hypervirulent one.
• Public Health Action: The emergence of this specific hv-XDR sub-lineage necessitates enhanced genomic surveillance, strict infection control measures, and regional cooperation to prevent the spread of this high-risk clone across the Eastern Mediterranean.