Decade-long Chinese surveillance shows falling MRSA and ESBL resistance, but carbapenem-resistant Klebsiella persists

A ten-year nationwide surveillance effort in China has mapped the shifting landscape of antimicrobial resistance in bloodstream infections with unusual precision, and its findings tell two very different stories at once. Between 2014 and 2023, researchers tracked more than 76,000 non-duplicate bloodstream infection isolates from 72 hospitals spanning 22 provinces of mainland China. The data reveal substantial, sustained declines in several major resistance phenotypes, including methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. Yet the same dataset shows that carbapenem-resistant A. baumannii has remained stubbornly entrenched at very high levels, while carbapenem-resistant K. pneumoniae (CRKP) more than doubled in prevalence over the decade, peaking sharply in 2018 before settling at a rate still twice that of 2014.

What distinguishes this study from most large surveillance networks is its centralised design. Rather than aggregating laboratory reports produced at each participating hospital, the researchers physically transferred every bloodstream isolate to a single reference laboratory in Hangzhou, where species were re-confirmed using MALDI-TOF mass spectrometry and susceptibility testing was performed under standardised conditions. Crucially, the team preserved the raw minimum inhibitory concentration values and retrospectively reinterpreted them against the 2025 Clinical and Laboratory Standards Institute guidelines, so that resistance categories remained comparable across ten years despite successive revisions to clinical breakpoints. This approach sidesteps the inter-laboratory variability and interpretive drift that complicate decentralised networks such as China’s CARSS system, which aggregates reports from more than 1,400 sentinel hospitals.

The final analytical cohort comprised 76,211 isolates after excluding non-viable cultures, specimens with inconsistent species identification, and clinical contaminants. Of these, 29,274 isolates came from a prespecified sentinel cohort of 14 hospitals that participated continuously for the entire decade, a design feature that allowed the investigators to test whether the network’s progressive expansion distorted observed trends. Using a binomial generalised linear model with a year-by-cohort interaction term, the team found no significant divergence between the sentinel and overall cohorts for most phenotypes, supporting the conclusion that the headline trends were not artifacts of changing hospital participation. Clinical metadata, including ward type, gender and age, were available for roughly 55 to 57 percent of isolates, and comparisons between isolates with complete and missing information showed maximum proportional differences well below a predefined 3 percent threshold, consistent with limited selection bias.

The pathogen spectrum itself shifted measurably over the decade. Gram-negative bacilli dominated throughout, with E. coli and K. pneumoniae the two most frequently isolated species in every year. K. pneumoniae’s share of bloodstream infections rose by an estimated 0.91 percentage points annually and E. coli’s by 0.66 points, while P. aeruginosa, S. aureus, A. baumannii and coagulase-negative staphylococci showed no significant overall linear shifts. The proportional contribution of coagulase-negative staphylococci fell steeply from 26.2 percent in 2014 to 9.2 percent in 2023, but this drop was concentrated in the first three years and likely reflects improving blood culture collection practices, such as better skin antisepsis and contaminant exclusion protocols, rather than a genuine epidemiological change in these common contaminants.

The resistance trajectories split cleanly into two camps. Three phenotypes declined significantly: ESBL-producing E. coli fell from 61.5 percent to 47.4 percent, methicillin-resistant S. aureus fell from 39.0 percent to 26.2 percent, and ESBL-producing K. pneumoniae fell from 30.5 percent to 21.5 percent, each with an estimated annual decrease of roughly one to 1.6 percentage points and all p values below 0.001. The authors suggest these declines may partly reflect the selective pressure reduction achieved by China’s 2011 national special rectification campaign, which imposed quantitative limits on prophylactic antibiotic use in clean surgery and restricted hospital procurement of third- and fourth-generation cephalosporins and fluoroquinolones. The steeper MRSA decline observed in China contrasts with smaller reductions reported in European surveillance over comparable windows, and similar falls in MRSA and ESBL-producing Enterobacterales have followed comprehensive stewardship programmes in other countries.

Carbapenem resistance told a contrasting story. CRKP prevalence more than doubled from 7.0 percent to 14.9 percent, with a striking peak of 22.5 percent in 2018, although the overall ten-year linear trend was not statistically significant. CRKP was the only phenotype showing a significant divergence between the overall network and the sentinel cohort, and post-hoc investigation traced this to a single newly enrolled hospital with an exceptionally high CRKP burden that joined in 2016 and dominated the national totals during 2017 and 2018. Once this centre was excluded, the overall and sentinel trajectories converged. The pattern is consistent with clonal transmission of hospital-adapted strains: genomic studies elsewhere in China have identified KPC-2-producing ST11 K. pneumoniae as the dominant epidemic lineage, accounting for 73.2 percent of KPC- and NDM-co-producing CRKP isolates in one analysis and evolving into a high-risk KL64 subclone with enhanced transmissibility.

Carbapenem-resistant A. baumannii, meanwhile, fluctuated between 55.2 and 64.3 percent of isolates across the decade with no clear declining trajectory, prompting the authors to describe it as an established endemic reservoir within Chinese healthcare facilities. The bacterium’s capacity to survive desiccation aids its persistence on hospital surfaces and equipment, particularly in intensive care units. Carbapenem-resistant P. aeruginosa showed the most volatile behaviour of all, peaking at 38.2 percent in 2020 before falling to 17.0 percent by 2023, a swing the study attributes to pronounced interannual and inter-centre variability rather than a stable trend.

The stratified analyses sharpen the picture of who and where is most at risk. Resistance proportions for all six core phenotypes were consistently higher in intensive care units than in non-ICU wards, most dramatically for CRAB at 83.2 percent versus 51.2 percent and CRKP at 38.7 percent versus 14.0 percent. Male patients showed significantly higher resistance than female patients for several phenotypes, including CRAB and CRKP and, contrary to expectations from earlier literature, ESBL-producing E. coli. Resistance rates also differed significantly across age groups, with Bonferroni-adjusted pairwise comparisons indicating distinct patterns particularly between paediatric and older populations, and geographic heatmaps revealed regional disparities in specific resistance markers. Notably, the subgroup-level temporal analyses showed that the national declines in MRSA and ESBL production were mirrored even within high-risk groups such as ICU patients and older adults, with CRKP across regions being the most prominent divergent signal.

The authors frame these findings as a data-driven argument for precision-targeted stewardship rather than uniform national policies. Because CRKP dynamics appear driven by clonal spread concentrated in a limited number of high-burden facilities, managing it plausibly requires measures beyond broad-spectrum antibiotic restriction, including genomic surveillance for early clone detection, rigorous patient isolation, environmental decontamination, and active screening in high-acuity wards. Intervention studies have associated outbreak control bundles combining single-room isolation, enhanced disinfection, surveillance and cohorting with reductions in CRKP cross-transmission. The international context reinforces the concern: the WHO’s 2025 Global Antibiotic Resistance Surveillance Report, covering more than 23 million isolates, found rising resistance in over 40 percent of monitored pathogen–antibiotic combinations between 2018 and 2023, directionally concordant with China’s CRKP rise but discordant with its MRSA and ESBL declines.

The study has acknowledged limitations. The dataset lacks whole-genome sequencing, so the clonal relationships suspected behind the CRKP surge could not be definitively confirmed, and the absence of linked patient-level longitudinal data prevents direct assessment of how resistance trends relate to clinical outcomes such as mortality. The platform is primarily bacterial, and fungal bloodstream isolates, though preserved, were not systematically tested for antifungal susceptibility. Even so, the decade-long record offers a rare, internally consistent national picture: coordinated stewardship appears to have bent the curve for some of the world’s most notorious resistant pathogens, while carbapenem-resistant Gram-negative bacteria, entrenched in ICUs and concentrated in a handful of facilities, remain the defining challenge for the next decade of resistance control in China and beyond.

Subject of Research: Longitudinal national surveillance of antimicrobial resistance in bloodstream infections in China, 2014–2023

Article Title: Spatiotemporal trajectories of antimicrobial resistance in bloodstream infections in China: a nationwide longitudinal surveillance study from 2014 to 2023

Article References: Chen, Y., Liu, Z., Ji, J., Ying, C., Zhang, H., Kong, H., Yang, Q., Shen, P., Xiao, Y., Liang, K., Zhang, P., Huang, Y., Shen, J., Dong, Y., Liu, Z., Lu, G., Xia, X., Du, F., Sun, L., … Qiang, X. (2026). Spatiotemporal trajectories of antimicrobial resistance in bloodstream infections in China: a nationwide longitudinal surveillance study from 2014 to 2023. The Lancet Regional Health – Western Pacific, 75, Article 102010. https://doi.org/10.1016/j.lanwpc.2026.102010

Image Credits: AI Generated

DOI: 10.1016/j.lanwpc.2026.102010

Keywords: antimicrobial resistance, bloodstream infections, MRSA, ESBL, carbapenem-resistant Klebsiella pneumoniae, Acinetobacter baumannii, surveillance, China, ICU, antimicrobial stewardship, Spatiotemporal, trajectories