Lytic bacteriophages targeting carbapenem-resistant Klebsiella pneumoniae isolated in a resource-limited Zambian laboratory.

Klebsiella pneumoniae is a major cause of healthcare-associated and community-acquired infections, increasingly complicated by multidrug resistance (MDR) and carbapenem-resistant K. pneumoniae (CRKp). Phage-based approaches are attractive in such settings but rely on infrastructure and expertise, which are not widely available in low-resource laboratories. Here, we describe the isolation and preliminary characterization of two lytic K. pneumoniae phages, Zm_01 and Zm_02, from hospital sewer sludge in Lusaka, Zambia, using only routine microbiology equipment and simple adaptations of standard protocols. Clinical K. pneumoniae isolates, including MDR and carbapenem-resistant (meropenem-resistant) strains, were used for enrichment, double-agar overlay plaque assays, host-range screening and determination of efficiency of plating (EOP). Zm_01, isolated on a non-MDR but hypermucoviscous host, produced small, clear plaques and exhibited efficient plating on several MDR isolates, with EOP values higher on some MDR strains than on its original host. Zm_02, isolated on an MDR strain, formed large, clear plaques with halos, consistent with capsule-degrading activity. All work was performed without access to specialized equipment, such as a spectrophotometer, a shaker incubator or standard imaging equipment. These findings demonstrate that discovery and basic phenotypic characterization of therapeutically relevant K. pneumoniae phages are feasible in low-resource settings and provide a practical workflow that can underpin future functional and genomic studies, as well as the development of locally tailored phage-based interventions against MDR and CRKp infections.