Epidemiological characteristics and temporal trends of major multidrug-resistant bacteria in a tertiary maternal and child health hospital from 2021 to 2024.

OBJECTIVE: To describe the distribution of major antimicrobial resistance phenotypes in a tertiary maternal and child health hospital from 2021 to 2024, to assess their temporal trends and seasonal patterns, and to explore possible phase-specific changes, so as to provide evidence for infection prevention and control and antimicrobial stewardship in maternal and child health settings. METHODS: This was a single-center ecological longitudinal time-series study. Positive bacterial isolates recovered from clinical specimens submitted from hospitalized patients at Luoyang Maternal and Child Health Hospital between January 1, 2021 and December 31, 2024 were collected. A first-isolate deduplication strategy was applied, whereby only the first isolate within 30 days was retained for the same patient, bacterial species, and specimen type. Resistance phenotypes were uniformly defined according to CLSI criteria. Descriptive analyses were performed for carbapenem-resistant Enterobacterales (CRE), extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), methicillin-resistant Staphylococcus aureus (MRSA), and carbapenem-resistant Pseudomonas aeruginosa (CRPAE). Among these, CRE, ESBL-E, and MRSA were included in the main trend analyses, whereas CRPAE was presented descriptively because of its low detection frequency. Differences across years, wards, and specimen types were compared using the χ² test. Quarterly trends and potential breakpoints were assessed using single-breakpoint segmented log-linear Poisson regression. Monthly generalized linear models (GLMs) based on aggregated data were used to evaluate overall temporal trends and seasonality. RESULTS: A total of 8,467 clinical isolates meeting the first-isolate criteria were included from 2021 to 2024. Annual analyses showed that ESBL-E and MRSA constituted the major resistance burden. The detection rate of ESBL-E decreased from 9.62% in 2021 to 3.55% in 2024, and that of CRE decreased from 2.52% to 0.34%, whereas MRSA increased from 10.96% to 12.73%. CRPAE remained at a low level throughout the study period (0.05%–0.30%). In terms of ward distribution, pediatric-related wards and the NICU accounted for a relatively high proportion, suggesting that the major resistance burden was more concentrated in neonatal and pediatric clinical units. Monthly GLM analyses showed that, after adjustment for seasonality, CRE exhibited an overall downward trend (IRR = 0.946, 95% CI: 0.930–0.962, P < 0.001), ESBL-E showed a slight downward trend (IRR = 0.992, 95% CI: 0.985–1.000, P = 0.041), and MRSA showed a slight upward trend (IRR = 1.005, 95% CI: 1.000–1.010, P = 0.031). All three phenotypes showed varying degrees of seasonal fluctuation. Exploratory quarterly segmented regression further suggested possible phase-specific changes in some resistance phenotypes; however, given the limited number of quarterly time points, these breakpoint findings should be interpreted with caution. CONCLUSIONS: From 2021 to 2024, the major resistance burden in this maternal and child health hospital was still mainly attributable to ESBL-E and MRSA. Although the overall detection rate of CRE was low, it still warrants continued attention in key wards. CRPAE was infrequently detected and should be regarded as a supplementary descriptive finding only. Marked heterogeneity was observed across resistance phenotypes in ward distribution, specimen sources, and temporal patterns. These findings provide single-center surveillance evidence to support stratified monitoring, targeted infection prevention and control, and antimicrobial stewardship in maternal and child health hospitals; however, their generalizability should be interpreted cautiously in conjunction with data from other institutions.