Microbial drug resistance最新文献

Background: The global dissemination of New Delhi metallo-β-lactamase-1 (NDM-1)-producing Escherichia coli (carbapenem-resistant Escherichia coli [CREC]) has escalated into a pressing public health crisis, driven by the rapid evolution of multidrug resistance and the scarcity of effective therapies. To address this challenge, this study focused on evaluating the therapeutic potential of eugenol, a natural phenolic compound, against NDM-1-CREC through integrated in vitro and in vivo approaches.

Methods: The in vitro antibacterial activity of eugenol was evaluated using the microbroth dilution method, growth curve, and time-antibacterial curve. The in vivo antibacterial activity of eugenol was studied by drawing survival curves, counting the live bacterial load in each tissue, measuring the expression of inflammatory factors, and histopathological observation. Morphology and ultrastructure were analyzed by SEM/TEM, cell wall integrity by alkaline phosphatase, biofilm by crystal violet staining, and gene expression by RNA-seq with RT-qPCR validation.

Results: In vitro experiments demonstrated that eugenol exerted rapid bactericidal effects, achieving complete eradication of CREC isolates within 2 hours, and enhanced the sensitivity of imipenem and meropenem. In vivo, eugenol significantly improved survival rates in a murine intraperitoneal infection model, reducing bacterial loads in peritoneal fluid and visceral organs (liver, lung, kidney, spleen; 2-3log10 colony-forming units [CFU]/mL reduction) while attenuating systemic inflammation (IL-6, TNF-α, IL-1β). Histopathological analysis further corroborated these results, showing marked alleviation of tissue damage in eugenol-treated cohorts. Mechanistic studies revealed that eugenol disrupted membrane integrity via structural damage (Scanning electron microscopy/transmission electron microscopy), suppressed biofilm formation (crystal violet assay), and downregulated resistance/virulence genes (mdtJ, ompA, csgD, flhD, fimB; RNA-seq/qRT-PCR validation).

Conclusions: These findings not only highlight eugenol's potential as a candidate drug but also provide a framework for repurposing natural compounds to combat carbapenemase-producing pathogens, offering a pragmatic strategy to mitigate the global antimicrobial resistance crisis.

Critically ill patients frequently undergo invasive procedures and receive broadspectrum antibiotics, both of which are associated with an increased risk of multidrugresistant organism (MDRO) bloodstream infections (BSI). However, the temporal relationship between these exposures during the early postprocedural period remains incompletely understood. We conducted a retrospective cohort study of 380 adult intensive care unit (ICU) admissions at The First Affiliated Hospital of Jinan University, Guangzhou, China, between 2020 and 2023. Propensity score matching (1:1, n = 248) was performed to balance age, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, baseline serum albumin level, and major comorbidities. Timedependent Cox proportional hazards models were used to evaluate the associations of invasive procedures (central venous catheterization or mechanical ventilation), carbapenem exposure, and their overlap with the development of MDRO BSI. Exploratory mediation analyses were conducted to assess the potential contributions of hypoalbuminemia and elevated C-reactive protein (CRP). Early postprocedural time windows were specifically examined. Overlapping exposure to invasive procedures and carbapenems was associated with a significantly higher risk of MDRO BSI compared with either exposure alone (adjusted hazard ratio [HR]: 4.0, 95% confidence interval [CI]: 2.2-7.3). The association was strongest within the first 12 hours after invasive procedures (HR: 5.1, 95% CI: 2.8-9.3) and remained elevated through 48 hours (HR: 3.3, 95% CI: 1.8-6.0). Exploratory mediation analyses suggested that hypoalbuminemia (serum albumin <30 g/L) and elevated CRP (≥50 mg/L) accounted for approximately 32% and 21% of the observed association, respectively. Patients with overlapping exposures also demonstrated lower 28-day infection-free survival than those in other exposure groups. In critically ill patients, carbapenem exposure occurring shortly after invasive procedures was temporally associated with an increased risk of MDRO BSI, particularly during the first 48 hours following the procedure. Host nutritional and inflammatory status may partially contribute to this association. These findings highlight the importance of considering exposure timing and patient vulnerability when evaluating early broad-spectrum antibiotic use in ICU settings.

Globally, Acinetobacter baumannii has emerged as an important nosocomial pathogen and as highly resistant to clinically relevant antibiotics, namely, carbapenems. In this study, we aimed to determine the epidemiological profile and the imipenem (IPM) resistance rate of a clinical collection of A. baumannii isolates. This study was carried out at the Central Laboratory of the Oran Regional University Military Hospital (Hôpital militaire régional universitaire d'Oran) over a period of 7 years (January 2010-December 2016). The frequency of A. baumannii isolates was not constant over the 7 years; however, an increasing trend was observed. Among the 168 isolates, the majority was isolated from male patients (n = 131, 78%). Patients in the intensive care unit had a higher risk of developing A. baumannii infection (76%) compared to other hospital services, and protected distal pulmonary samples were the main site of isolation of A. baumannii isolates (34%). Among the collected isolates, 106 were IPM resistant and exhibited multidrug phenotypes. These results confirm the multidrug-resistant nature of A. baumannii and its nosocomial behavior. The emergence of this bacterial species represents a serious therapeutic and epidemiological problem, hence the need for the establishment of a system for monitoring the microbial environment of the hospital and the strict application of hygiene measures.

Certain subgroups of men who have sex with men (MSM) may be characterized by increased antimicrobial exposure and sexual network patterns that favor the emergence and dissemination of antimicrobial resistance. This retrospective study investigated the distribution of selected tetracycline- and β-lactam resistance genes in the oropharyngeal and anorectal mucosa of MSM attending a sexually transmitted infection (STI) clinic and explored their association with demographic and behavioral variables. In early 2025, 49 MSM attending the STI Clinic of IRCCS Azienda Ospedaliero Universitaria in Bologna, Italy, were enrolled. Participants completed a questionnaire and underwent pharyngeal and anorectal swabbing. End-point polymerase chain reaction assays were used to detect tetracycline resistance genes (tet(X), tet(O), tet(W), tet(Q)) and β-lactamase genes (blaOXA-2, blaTEM, blaSHV, blaCTX-M). Overall, 20/49 participants (40.8%) reported antibiotic use in the previous 6 months, and 19/49 (38.7%) reported having >6 sexual partners during the same period. At least one tetracycline resistance gene was detected in all participants (49/49; 100%) at both anatomical sites. In contrast, at least one β-lactamase gene was identified in 38/49 (77.6%) oropharyngeal samples and 42/49 (85.7%) anorectal samples. No statistically significant associations were observed between β-lactamase gene carriage and the variables analyzed. However, in the oropharyngeal mucosa, a numerically higher prevalence was observed among individuals reporting >6 sexual partners, although the difference was not statistically significant (p = 0.061). The oropharyngeal and anorectal mucosae of MSM may represent reservoirs of antimicrobial resistance genes. These findings provide descriptive evidence of the widespread distribution of resistance determinants and highlight the need for further studies to clarify their drivers and clinical relevance.

This study investigated the characterization of antimicrobial resistance (AR) profiles and β-lactamase production in Escherichia coli isolates recovered from cultured fish, with particular emphasis on plasmid-mediated resistance (PMR) determinants, including quinolone resistance (qnr), colistin resistance (mcr-1 to mcr-5) genes, class 1 integrons (intI1), and phylogenetic backgrounds, using PCR-based methods. From 64 cultured fish samples collected between 2024 and 2025, 34 E. coli isolates were obtained following cultivation on Harlequin^® E. coli/Coliform Agar and subsequently confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and Sanger sequencing. Antimicrobial susceptibility testing against 22 agents representing 11 antibiotic classes revealed resistance frequencies ranging from 5.88% to 50.00%, with the highest resistance rates observed for penicillins (67.65%) and cephalosporins (23.53%). Multidrug resistance was identified in 11.76% of the isolates. All isolates exhibited extended-spectrum β-lactamase (ESBL) activity, predominantly associated with bla_TEM (91.18%), bla_SHV (58.82%), and bla_CTX-M (23.53%). Carbapenemase-encoding genes were detected in 38.23% of the isolates, mainly bla_IMP (14.71%) and bla_OXA-48 (11.76%), while plasmid-borne AmpC genes (CITM and DHA) were identified in 5.88% of the isolates each. Co-carriage of ESBL and carbapenemase genes occurred in 38.23% of isolates, whereas concurrent detection of ESBL and AmpC genes was observed in 8.82%. Plasmid-borne quinolone resistance genes, primarily qnrS and qnrB, were detected in 64.70% of the isolates, and intI1 was identified in 38.23%; however, no mcr genes were detected. Phylogenetic analysis showed that most isolates (73.53%) belonged to phylogroup B2₃. Notably, phenotypic resistance profiles did not fully correspond with PCR-based genotypic findings, highlighting the complexity of AR expression in aquatic E. coli. In conclusion, cultured fish were found to harbor a high proportion of multidrug-resistant and β-lactamase-producing E. coli. The simultaneous detection of ESBL, carbapenemase, AmpC, and PMR genes suggests that aquaculture systems may contribute to the persistence and spread of AR. Continuous monitoring within a One Health framework is therefore essential to reduce risks to food safety and public health.

ICESan95 is a serine integrase integrative and conjugative element (ICE) that targets methyltransferase genes for integration. The mosaic ICE ICESag084 contains ICESan95 and partial fragments from two distinct genes (snf2 and hsdM), suggesting a recombination event. This study aimed to experimentally investigate the recombination of multiple ICESan95, leading to the formation of a mosaic ICE resembling ICESag084. Using conjugation assays, we tracked this evolutionary process, confirmed the structures via whole-genome sequencing, and assessed genomic stability through serial passages. Analysis showed that ICESag084 comprises an ICESan95-like ICE, a tyrosine integrase element, and a partial ICESpy009 sequence. The ICESan95-like ICE was flanked by truncated snf2 and hsdM genes, indicating ancestral cointegration of two ICESan95-like ICEs followed by excision and sequence capture. Experiments confirmed that tandem integration of ICESan95 into adjacent snf2 (from an ICESpy009-like element) and hsdM(from the tyrosine integrase element) sites facilitated recombinational excision. This event deleted an ∼36.6-kb intervening fragment, yielding an ∼86.5-kb circularized intermediate and generating an ∼81.0-kb mosaic ICE highly similar to ICESag084. The mosaic ICE was conjugatively transferable and remained stable for ≥60 generations, while the circularized ICE was lost within 20 generations. Thus, tandem integration and recombinational excision drive the emergence and spread of mosaic ICEs. This mechanism facilitates the modular assembly of multiple mobile genetic elements, including ICESpy009, ICESan95, and a tyrosine integrase element. This process creates novel resistance islands with expanded traits, providing a key pathway for long-term adaptive evolution in bacterial pathogens.

The emergence of Escherichia coli sequence type (ST131), especially its H30Rx subclade, has reshaped the epidemiology of urinary tract infections (UTIs) by combining multidrug resistance (MDR), extended-spectrum β-lactamase (ESBL) production, and biofilm formation. Clinical E. coli isolates were genotyped for ST131 and H30Rx using PCR. Antimicrobial susceptibility, ESBL activity, biofilm formation, and plasmid carriage were assessed through standard protocols. Statistical tests were applied to explore associations between clonal types and resistance traits. Nearly half of the isolates (46.3%) were identified as ST131, with 78.9% belonging to H30Rx. Overall, eight isolates (19.5%) were ESBL producers. ESBL production was significantly higher in ST131 (36.8%) compared with non-ST131 (4.5%; p = 0.004). Plasmid carriage was universal in ST131 (100%) and more frequent than in non-ST131 (86.4%; p = 0.029). MDR was observed in almost 90% of ST131 isolates. Biofilm formation was widespread (97.5%), with all ST131 strains positive. Resistance was greatest against fluoroquinolones and third-generation cephalosporins, while fosfomycin, nitrofurantoin, and amikacin retained high activity with low resistance rates. The predominance of ST131, particularly H30Rx, highlights its role as a high-risk clone driving ESBL production, plasmid-mediated resistance, and biofilm-associated persistence in UTIs. Given the rising resistance to commonly used antibiotics, fosfomycin, nitrofurantoin, and amikacin remain promising therapeutic options. Key limitations include a modest sample size (n = 41 E. coli isolates), the absence of genotypic ESBL characterization, and the use of disk diffusion for fosfomycin and nitrofurantoin without MIC confirmation. Continuous surveillance, molecular characterization, and strengthened antimicrobial stewardship are essential to control the spread of this lineage and preserve treatment efficacy.

The current study was conducted to determine the antibiotic resistance profile and prevalence of extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli among the uropathogenic E. coli (UPEC) strains (n = 100), isolated from patients with urinary tract infection (UTI) in Hamedan, western Iran. In addition, the molecular prevalence of antibiotic resistance genes (ARGs) and ESBL genes among these strains was investigated using polymerase chain reaction. Out of 100 UPEC isolates, 46 (46%) and 40 (40%) isolates were phenotypically identified as multidrug-resistance (MDR) strains and ESBLs producer strains, respectively. UPEC isolates showed the highest resistance to trimethoprim/sulfamethoxazole (55%), followed by amoxicillin (51%) and ampicillin (45%). The most prevalent ARG in UPEC strains was tetA (10%), followed by aadA1 (9%), sul1 (9%), qnrs (7%), and dfrA1-like (3%). Among the 40 UPEC isolates that phenotypically confirmed as ESBL producers, 19 (475%) isolates harbored bla_CTX-M gene, 9 (22.5%) harbored bla_TEM gene, 8 (20%) harbored bla_OXA gene, and 4 (10%) harbored bla_CIT-M. The ESBL gene bla_CTX-M displayed a significant association with ESBL phenotypic isolates at p value <0.05. Due to the relatively high prevalence of MDR-UPEC strains and ESBLs producer UPEC isolates among patients with UTI reported herein and also regarding incidence of ARGs and β-lactamase gene among these isolates, applying precise antibiotic stewardship, continuous surveillance to use appropriate antibiotics, and the control of UTI infections seem necessary to decrease ESBLs producer UPEC and MDR-UPEC strains.

Plasmid-mediated colistin resistance in food animals is a major public health concern, but longitudinal farm data remain limited. We screened 10 broiler farms in Guelma, Algeria, for mcr-1-positive colistin-resistant Escherichia coli and monitored three positive farms over 8 months. Among 186 pooled animal and environmental samples, 54 isolates were recovered, and all carried mcr-1. Positive isolates were detected in chicken feces and environmental niches, including drinking water, wastewater, wall swabs, and soil. The population was polyclonal, comprising 28 sequence types, but ST162, ST93, and ST3941 recurred across farms or sampling periods. Four ST162 isolates from farm C recovered from successive flocks differed by only 12-14 SNPs, supporting local persistence or repeated reintroduction from a common reservoir. All isolates were multidrug resistant and carried mcr-1 on an IncI2 (delta) plasmid. These findings support a mixed epidemiology combining persistence of selected clones with horizontal dissemination of a conserved mcr-1-bearing plasmid in poultry farms.