Summary
A bioRxiv preprint found that many capsule types in Pakistani carbapenem-resistant Klebsiella pneumoniae genomes have no phage described in the literature. It identifies the South Asian capsule type KL81 as a target for future phage-isolation work.
A genomic and literature analysis in a bioRxiv preprint found that 121 of 254 clinical Klebsiella pneumoniae genomes from Pakistan belonged to capsule types with no phage described in the literature. The authors, Talal Ahmed and Ahmed Hussain Shah, identify the South Asian capsule type KL81 as a specific target for future phage-isolation work.
The study compared bacterial genomes with a curated set of published phage and depolymerase records. Its findings point to a gap between the capsule types present in the sampled Pakistani genomes and those represented in the phage literature.
Many Pakistani capsule types had no described phage
The researchers typed 254 clinical K. pneumoniae genomes from Pakistan and assembled 34 phage–capsule records covering 27 phages and 15 capsule types. They found that 121 isolates—47.6% of the Pakistani group—spanned 51 of the 66 capsule types identified and belonged to types for which no phage had been described. Sixty-seven of those isolates carried a carbapenemase.
The capsule is a surface layer on the bacterium. Its type matters for phage research because many Klebsiella phages bind to a single capsule type. A phage that infects bacteria with one type may therefore not be useful against strains carrying a different one.
As a check on the composition of the genome dataset, the authors counted only one isolate per capsule type within each BioProject. With that adjustment, the unmatched fraction rose to 51.8%.
KL81 stands out in the regional comparison
The team also typed 475 genomes from India, Bangladesh and Nepal, China, Europe and the United States using the same criteria. KL81 accounted for 6.3% of the South Asian genomes and was absent from 275 genomes from China, Europe and the United States. The authors report that no phage for KL81 has been published.
KL107 showed the opposite regional pattern: it made up 9.8% of genomes from China, Europe and the United States and was absent from the South Asian group. Both differences persisted when the analysis accounted for clustering within BioProjects; the reported P values were 0.0014 for KL81 and 0.0002 for KL107. Six other apparent regional differences did not persist under that adjustment, which the authors attribute to clonal expansion within individual studies.
The authors argue that phage collections reflect where researchers isolate phages and which local bacterial hosts they use. On that basis, KL81 offers a defined priority for phage isolation in South Asia. The study maps genomes and published phages; it is not a phage-treatment trial, so its contribution is to identify a research target rather than demonstrate a clinical benefit.