Study Reveals Widespread Community Spread of Drug-Resistant Klebsiella

Determining how this organism circulates outside hospitals has remained unclear, limiting targeted surveillance. Genomic analysis of large, representative isolate sets can clarify dissemination and resistance mechanisms. Researchers now report a nationwide assessment that identifies widespread, underrecognized community reservoirs across the United States.

At the Hackensack Meridian Center for Discovery and Innovation (CDI), in collaboration with Quest Diagnostics, investigators analyzed more than 2,000 Klebsiella pneumoniae isolates collected across 42 U.S. states. The study, published in Nature Communications as “Nationwide spread of multidrug resistant Klebsiella pneumoniae across U.S. communities,” leveraged a national diagnostic network to assemble a diverse sample set. Quest Diagnostics provided deidentified culture isolates classified as antibiotic resistant, which CDI then sequenced to characterize strain diversity and resistance determinants.

The analysis indicates that plasmid-borne drivers underpin the spread of resistance, with CTX-M-15 identified as a principal gene transferring between bacteria. According to the findings, this element has disseminated to hundreds of strains and is associated with both antimicrobial resistance traits and tolerance to stress and metal exposure, potentially enhancing survival outside human hosts. Geographic patterns showed regional, statewide, and multistate dissemination, consistent with underrecognized community reservoirs.

Across the more than 2,000 screened samples, 267 multidrug-resistant sequence types were identified. Two-thirds of specimens were from female patients and about three-quarters from individuals older than 60 years. All isolates examined were classified as multidrug resistant, and nearly 70% were resistant to three common oral agents—fluoroquinolones, Bactrim, and nitrofurantoin—indicating that, for some patients, injectable antibiotics may be the only viable option.

The work situates community transmission within a broader trend, building on prior observations of expanding extended-spectrum beta-lactamase (ESBL) reservoirs and a U.S. Centers for Disease Control and Prevention study that documented a 53.3% rise in ESBL-producing bacteria between 2012 and 2017. The authors describe the present dataset as a baseline for ongoing risk tracking. While strengths include national scope and a focus on community infections, a key limitation is the absence of detailed patient medical histories, which constrains inference about infection sources.

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