Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a formidable nosocomial pathogen, with healthcare environments acting as critical reservoirs for its dissemination. In this study, we investigated the prevalence, antimicrobial resistance profiles and genomic characteristics of CRAB isolates collected from hospitals in Shanghai, China, between June and December 2024, identifying ST2 ^Pas (84.13%) and ST164 ^Pas (15.08%) as the predominant lineages among the 126 CRAB isolates recovered from clinical ( n =94), environmental ( n =29) and healthcare worker ( n =3) sources. Environmental CRAB accounted for the highest proportions on patient-contact surfaces (34.48%), medical devices (31.03%) and shared items (24.14%). Within the dominant ST2 ^Pas lineage, clinical isolates exhibited higher resistance rates to ampicillin/sulbactam, cefoperazone/sulbactam and levofloxacin, with significantly higher carriage rates of bla _TEM-1D compared to environmental isolates. Compared to ST164 ^Pas , ST2 ^Pas CRAB isolates exhibited greater resistance to amikacin, gentamicin, trimethoprim/sulfamethoxazole and minocycline and a higher prevalence of aph (3′)-Ia, aph (3″)-Ib, aph(3′ )-VI, aph (6)-Id, arm A, bla _OXA-66 , bla _TEM-1D , mph (E) and tet (B), but lower rates of bla _CARB-16 , bla _NDM-1 and bla _OXA-91 ( P< 0.05). Notably, comparative genomic analysis suggested putative adaptive differences between the two lineages. ST2 ^Pas retained the T6SS and biofilm-associated genes ( bap ), descriptive genomic features that suggest a potential capacity for active colonization. Conversely, the ST164 ^Pas clone lacked the T6SS gene cluster but was enriched with the surface adhesin ata and immune evasion-related genes. Concordantly, ST164 ^Pas CRAB isolates exhibited significantly stronger biofilm-forming capacities than ST2 ^Pas in vitro . We hypothesize that these genomic alterations and phenotypic traits may represent a fitness trade-off, potentially conferring a survival advantage under antibiotic pressure. Furthermore, bla _OXA-23 in ST2 ^Pas was predominantly carried on conjugative plasmids restricted to Acinetobacter species, whereas bla _NDM-1 in ST164 ^Pas was localized on a broad-host-range non-mobile plasmid, potentially facilitating cross-genus transmission. Although our ST164 ^Pas isolates shared high homology with clinical strains from Zhejiang, China, the genomic localization of bla _NDM-1 differed between the plasmid and chromosome, respectively. These descriptive genomic findings highlight the putative adaptive trajectories of the predominant ST2 ^Pas and emerging ST164 ^Pas clones, underscoring the critical need for comprehensive genomic surveillance, complemented by future phenotypic validation, to monitor their rapid evolution and dissemination.

Background: In China, Carbapenem-resistant Klebsiella pneumoniae (CRKP) is dominated by sequence type 11 (ST11) harbouring KPC-2, with KL64 displacing KL47 and KL25 emerging. ST859 (ST11 variant) has caused outbreaks, but its epidemiology is unclear. Materials and Methods: A total of 99 non-duplicate CRKP isolates were collected from June to December 2024. Antimicrobial susceptibility was determined by broth microdilution. The genomic sequences of the strains were obtained using next-generation sequencing technology. Resistance genes, virulence loci, and plasmid replicons were identified with Kleborate, Abricate, and MOB-suite, respectively. Results: ST11 accounted for 63.64% and ST859 for 15.15%. All ST859 were KL19, while ST11 were mainly KL25 (60.32%) and KL64 (26.98%). 76.8% co-harbored carbapenemase and extended-spectrum beta-lactamase (ESBL) genes, with KPC-2 and CTX-M-65 being the predominant types. Susceptibility rates were 100% to tigecycline, and 78.79% to ceftazidime/avibactam. ST859 CRKP isolates exhibited higher phenotypic resistance to tetracycline and colistin than ST11 CRKP isolates (p < 0.05), and carrying LAP-2, QnrS1, QnrS10, and tet(A) more frequently. ST11-KL25 showed higher resistance to amikacin, gentamicin, and chloramphenicol, with increased prevalence of CTX-M-65, TEM-1, rmtB, catA2, and dfrA14 compared to ST11-KL64 (p < 0.05). IncF was the most prevalent replicon and both ST859 and ST11 CRKP carry conjugative resistance plasmids, and the host range is predominantly Enterobacterales. Conclusions: ST859-KL19 ranks second to ST11 with higher resistance to tetracyclines and colistin. ST11-KL25 may have already displaced ST11-KL64 as the predominant capsular type in Shanghai, with distinct resistance profiles between KL variants. Long-term, multicenter surveillance is urgently needed to delineate the evolutionary trajectory and clinical impact of these emerging clones.

Background: Nursing homes are congregate settings for elderly individuals where infectious diseases can easily spread. The elderly are at high risk of contracting and dying from influenza, and the most effective way to prevent this is to receive the influenza vaccine. Methods: This study conducted a cross-sectional survey of elderly people in nursing homes to investigate the occurrence of influenza symptoms during the 2024–2025 flu season, as well as vaccination status and reasons for receiving or not receiving the vaccine. Bivariate logistic regression was used to determine the factors influencing the vaccination rate. Results: Of the 1024 elderly people who participated in the survey, 25.39% reported experiencing flu-related symptoms in the previous flu season. While 16.21% of the elderly expressed willingness to receive vaccination, only 5.57% actually received it. Influenza vaccination was positively correlated with educational attainment (aOR 3.800, 95% CI 1.480–9.758 for middle school; aOR 5.138, 95% CI 1.738–15.191 for high school), monthly household income (aOR 0.216, 95% CI 0.072–0.644 for >8000), ability for self-care (aOR 0.269, 95% CI 0.123–0.591), and the scale of the nursing home (aOR 9.033, 95% CI 1.531–53.305 for 151–299; aOR 2.629, 95% CI 1.359–5.084 for ≥300). Willingness to receive the influenza vaccination was positively correlated with an unhealthy health status (aOR 0.398, 95% CI 0.204–0.779), symptoms of influenza (aOR 2.730, 95% CI 1.861–4.007), nursing home location (aOR 1.537, 95% CI 1.099–2.941 for outer suburbs), and the scale of the nursing home (aOR 1.991, 95% CI 1.154–3.435 for 151–299; aOR 2.158, 95% CI 1.374–3.390 for ≥300). Most elderly people who received the vaccine believed that vaccination could effectively prevent flu and that it could reduce the risk of complications, the rest were not vaccinated due to concerns about adverse reactions, mobility issues, or the distance to vaccination sites. Conclusions: Low awareness of flu vaccines and physical inability to travel to vaccination sites may be potential barriers to receiving the flu vaccine. It is worrying that the influenza vaccination rate is low among the elderly in nursing homes in Shanghai. As a result, it is crucial to prioritize targeted monitoring and intervention strategies for vulnerable populations living in collective institutions.