Search Results (1,329)

Background: Despite its typically self-limiting course, acute diarrheal disease continues to be clinically relevant from an antimicrobial resistance surveillance perspective. In-depth analyses at a national level remain limited, with available Romanian studies from the last decade focusing on individual pathogens, often relying on a restricted isolate collection. In this context, we aimed to evaluate antimicrobial resistance profiles and distribution of Salmonella spp., Campylobacter spp., Escherichia coli, Yersinia spp. and Shigella spp. Methods: Data was obtained from records from the Microbiology Laboratory of a tertiary-care hospital serving the south region of Romania, over a 3-year period. Results: Campylobacter spp. had high resistance rates to ciprofloxacin (81.65% for C. jejuni; 85.15% for C. coli) and tetracycline (44.65% for C. jejuni; 56.07% for C. coli). Erythromycin resistance remained low and stable over the study period, with no statistically significant temporal variation; however, C. coli isolates demonstrated significantly higher erythromycin (p = 0.001) and tetracycline (p = 0.008) resistance rates compared to C. jejuni. Overall Salmonella spp. resistance rate to ciprofloxacin was 46.00%, with higher resistance observed in serogroups C (63.64%) and D (52.53%) (p < 0.01). Ampicillin (AMP) resistance varied significantly across years and serogroups, with serogroup B consistently demonstrating higher resistance rates (40.48%) (p < 0.001). E. coli isolates reacting with pathotype-associated O antisera revealed high resistance levels to ampicillin (41.57%), amoxicillin–clavulanic acid (AMC) (38.73%) and sulfamethoxazole–trimethoprim (SXT) (19.25%), with low resistance levels to ciprofloxacin (9.04%) and ceftriaxone (CRO) (9.71%); no significant variation in resistance patterns was identified across years or serological pools, suggesting a relatively stable resistance profile over the study period. Yersinia spp. isolates showed no notable antimicrobial resistance levels. Shigella spp. isolates exhibited high resistance for ampicillin (78.57%), sulfamethoxazole–trimethoprim (68.75%), amoxicillin–clavulanic acid (50.00%) and ceftriaxone (35.41%). Conclusions: This study addressed a recognized gap in Romanian and Eastern European surveillance data and aims to contribute to a stronger evidence base for future epidemiological investigations and antimicrobial stewardship efforts. Resistance rates identified in our study may provide valuable information for comparison with data generated from veterinary, food and environmental surveillance programs, thereby supporting a more comprehensive understanding of antimicrobial resistance (AMR) epidemiology. These findings may additionally contribute to the development of coordinated strategies aimed at mitigating the emergence and spread of AMR. Full article

Background/Objectives: Formulating antibiotics as active pharmaceutical ingredient ionic liquids (API-ILs) has been proposed as a strategy to help overcome antimicrobial resistance. However, the effects of API-ILs on bacterial mutation frequency, an increase of which is associated with a higher risk of resistance development, have not yet been assessed. Here, API-ILs based on the antibiotic ciprofloxacin were synthesized using five structurally different counter ions of varying biological activity - low ([Chol]⁺ and [EMMor]⁺), intermediate ([TMC₁₀A]⁺) and high ([TMC₁₆A]⁺ and [TC₈MA]⁺) - and investigated in terms of their antimicrobial activity and mutation frequency in Escherichia coli MG1655. Methods: API-ILs were synthesized according to the CBILS© route. Conductivities and antimicrobial activity (determined by minimal inhibitory concentrations (MICs) and disk diffusion (DD) assays) of API-ILs as well as of individual API and ILs were measured, followed by mutation frequency assays. Results: Five novel ciprofloxacin-based API-ILs were synthesized. Overall, a lower dissociation of API-ILs compared to the respective ILs was observed, indicating presence of stable ion pairs in aqueous solution. All API-ILs retained the antimicrobial activity of ciprofloxacin. A higher mutation frequency (2.6–6.99-fold increase) was observed for API-ILs than for ciprofloxacin alone (1.71-fold increase), when compared to no treatment control, while ILs alone had no or a moderate impact (0.62–1.65-fold increase). Conclusions: Although it is possible to synthesize novel stable API-IL compounds with a high antimicrobial activity using ciprofloxacin and ILs of different structural classes, this can result in increased bacterial mutation frequencies. It is therefore crucial to improve our understanding of how API-ILs can be designed in a safer way. Full article

Background: Creating antibiograms solely for adults may overestimate resistance of antimicrobials for certain pathogens in children. The Canadian Paediatric Society comments that areas with no cephalosporin-resistant Streptococcus pneumoniae cases should consider ceftriaxone or cefotaxime monotherapy for meningitis, despite most experts recommending adding vancomycin. The present study created age-specific antibiograms using LifeLabs data to report incidences of resistant bacterial meningitis pathogens at the regional level to determine the need for duo-coverage. Methods: Data of common bacterial meningitis pathogen susceptibility was collected from 1 January 2023 to 31 December 2024, in the LifeLabs community laboratory on Vancouver Island. Results: Most Streptococcus pneumoniae isolates (78/83) were susceptible to ceftriaxone using the meningitis breakpoint; the remaining five isolates showed intermediate susceptibility to ceftriaxone. There was a significant difference when comparing S. pneumoniae susceptibility using penicillin-meningitis and penicillin-non-meningitis breakpoints (82% vs. 99%, respectively; p < 0.05). There was a significant difference between the three age groups (<18 years, 18–50 years, >50 years) when analyzing ciprofloxacin susceptibility of isolates [82% (n = 462), 77% (n = 2452), 75% (n = 8352), respectively, p < 0.05]. Conclusions: Ceftriaxone should remain the drug of choice for community-acquired bacterial meningitis and might be sufficient as a monotherapy for pneumococcal meningitis on Vancouver Island. The age-specific differences in E. coli susceptibilities to ciprofloxacin showed the importance of age-specific antibiograms. Full article

Tropical coastal waters are increasingly recognized as critical reservoirs for virulent, antibiotic-resistant enteric pathogens, yet seasonal dynamics governing their spatial distribution remain poorly characterized. We hypothesized that hydrological shifts and anthropogenic nutrient enrichment drive the seasonal distribution, virulence profiles, and antimicrobial resistance (AMR) of Escherichia coli, Salmonella spp., and Shigella spp. in the Jaffna Peninsula, Sri Lanka. Across 25 coastal sites during dry and transitional seasons, we integrated physicochemical water quality assessment, culture-based enumeration, PCR-based virulence gene profiling, Minimum Inhibitory Concentration (MIC) assays, GIS mapping, and statistical analyses. Key water quality parameters, including ammonium, nitrite, and total phosphorus, showed significant seasonal variation (p < 0.05), reflecting distinct hydrological regimes across seasons. A total of 220 E. coli, 200 Salmonella spp., and 100 Shigella spp. isolates were examined for virulence gene profiles and antibiotic tolerance. E. coli was detected at 80–88% of sites, Salmonella spp. at 72–88%, and Shigella spp. at 32–48%. Among E. coli isolates, stx1 was detected at 20–28% of sites and eae at 16% across both seasons. The stn gene was detected in Salmonella spp. at 12–28% of sites seasonally. Virulence profiling confirmed STEC harbouring stx1, stx2, and eae; Salmonella spp. carried stn; and Shigella spp. possessed invasion-associated genes. Trimethoprim–sulfamethoxazole resistance was recorded in 63.2% of E. coli, 33.0% of Salmonella spp., and 31.0% of Shigella spp. isolates at the lowest tested concentration of 4 µg/mL., while ciprofloxacin and piperacillin–tazobactam retained greater efficacy. Correlation analyses revealed significant associations among faecal contamination, nutrient enrichment, and virulence gene prevalence, implicating untreated sewage discharge and eutrophication as likely ecological factors associated with pathogen occurrence. These findings designate the Jaffna coastal zone as a significant reservoir of virulent AMR enteric pathogens, underscoring the urgent need for integrated One Health surveillance and seasonally adaptive coastal water quality management. Full article

Urinary tract infections (UTIs), particularly catheter-associated UTIs (CAUTIs), represent a significant clinical problem due to the predominance of Gram-negative uropathogens, their ability to form biofilms, and the increasing prevalence of antimicrobial resistance, which together reduce the effectiveness of conventional antibiotic therapy. This study aimed to evaluate the antimicrobial activity of selected natural plant-derived compounds against clinical Gram-negative uropathogens isolated from CAUTIs. The antibacterial effects of gallic acid, quercetin-3-D-glucuronide, and apigenin were assessed against Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, including both ciprofloxacin-susceptible and -resistant strains. Antimicrobial activity was determined using the broth microdilution method, followed by quantitative assessment of bacterial viability based on colony-forming unit (CFU) enumeration. Gallic acid exhibited the strongest concentration-dependent inhibitory activity, reducing bacterial viability by up to 2–3 log₁₀ CFU across all tested species. Quercetin-3-D-glucuronide demonstrated moderate antibacterial effects with a predominantly bacteriostatic profile, resulting in a partial but consistent reduction in CFU counts. In contrast, apigenin showed only weak effects on bacterial viability under the applied experimental conditions. None of the tested compounds achieved complete bacterial eradication. These findings indicate that gallic acid and quercetin-3-D-glucuronide possess inhibitory activity against Gram-negative uropathogens, including antibiotic-resistant strains, supporting their potential use as adjunctive agents targeting bacterial persistence in UTIs rather than as standalone antimicrobials. In the present study, the viability of planktonic bacterial cells was assessed; however, future studies should focus on evaluating the direct impact of the tested compounds on biofilm structure and biofilm formation dynamics. Full article

Background/Objectives: Antimicrobial resistance (AMR) in Staphylococcus spp. associated with poultry production is an emerging concern with implications for animal and public health. This study aimed to characterize antimicrobial susceptibility patterns and detect targeted methicillin resistance determinants in Staphylococcus isolates recovered from broiler chickens affected by bacterial chondronecrosis with osteomyelitis (BCO). Methods: A total of 200 bacterial isolates were evaluated, of which 167 were confirmed as Staphylococcus spp. Species identification was performed using presumptive phenotypic characterization followed by 16S rRNA gene sequencing. Antimicrobial susceptibility was assessed using disk diffusion, while presumptive methicillin-resistant phenotypes were evaluated using oxacillin screening and CHROMagar MRSA. Targeted molecular detection of mecA and mecC was performed by PCR. Results: The isolates demonstrated substantial species diversity, with S. aureus as the predominant species. Antimicrobial resistance was mainly observed against β-lactam antibiotics, particularly penicillin (33.5%), whereas high susceptibility was retained for non-β-lactam agents, including ciprofloxacin, tetracycline, trimethoprim–sulfamethoxazole, and azithromycin. A targeted PCR detected mecA in 7.2% of isolates, while mecC was not detected. The detection of mecA in oxacillin-susceptible isolates suggested genotype–phenotype discordance. Conclusions: BCO-associated Staphylococcus spp. from broiler chickens showed diverse species distribution, penicillin-dominant resistance, and targeted mecA detection across multiple species, supporting the use of combined phenotypic and molecular approaches for methicillin resistance surveillance. Full article

Background/Objectives: Antimicrobial resistance and bacterial persistence underscore the need to develop new chemotypes with multifunctional antibacterial mechanisms. This study aimed to design, synthesize, and evaluate curcumin-inspired 3,5-diarylidene-4-piperidones as versatile small molecules exhibiting antibacterial, antibiofilm, anti-efflux, DNA gyrase-inhibitory, and antiproliferative properties. Methods: A targeted series of triazole-conjugated 3,5-diarylidene-4-piperidones was synthesized through copper-catalyzed azide-alkyne cycloaddition click chemistry and subsequently characterized using standard spectroscopic techniques. The compounds were assessed for antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. Selected active compounds underwent further evaluation for DNA gyrase inhibition, antibiofilm activity against multidrug-resistant S. aureus ATCC 33591, ethidium bromide accumulation, and antiproliferative effects on HCT116 and MCF7 cancer cells, with RPE1 cells serving as a control to evaluate cytotoxicity in normal cells. Additionally, computational studies, including QSAR analysis and molecular docking, were conducted to bolster structure–activity relationships and provide mechanistic insights. Results: Several derivatives demonstrated selective antibacterial activity against Gram-positive bacteria, particularly S. aureus, while exhibiting limited or no efficacy against E. coli. Compounds 7n and 7l emerged as the most potent against S. aureus, with minimum inhibitory concentrations (MICs) of 7.8 and 8.2 μM, respectively. Notably, compound 7l inhibited S. aureus DNA gyrase supercoiling, displaying an IC₅₀ of 3.20 μM, comparable to ciprofloxacin. Compound 7e exhibited the strongest antibiofilm activity against multidrug-resistant S. aureus, whereas compound 7a resulted in the highest accumulation of ethidium bromide, indicating robust anti-efflux activity. Antiproliferative assays revealed that select halogenated derivatives were effective against HCT116 and MCF7 cells, while the most promising antibacterial compounds exhibited minimal cytotoxicity toward RPE1 cells. Quantitative structure–activity relationship (QSAR) and docking studies supported the observed structure–activity relationships and suggested potential interactions with the ATPase binding site of DNA gyrase B. Conclusions: Triazole-conjugated 3,5-diarylidene-4-piperidones are promising multifunctional scaffolds with selective anti-S. aureus activity, antibiofilm and anti-efflux properties, and, for compound 7l, potent DNA gyrase inhibition. These findings support further optimization of this chemotype as a platform for developing antibacterial agents with polymechanistic activity. Full article

Companion animals are increasingly recognized as carriers of antimicrobial-resistant Escherichia coli, yet genomic data from clinically healthy dogs in Latin America remain scarce. We characterized 13 genetically non-redundant multidrug-resistant E. coli isolates selected from 224 resistant E. coli isolates recovered in a previous surveillance study of 600 clinically healthy household dogs in the Metropolitan Region of Chile (2021–2022). Antimicrobial susceptibility testing was performed using VITEK2 and interpreted according to Clinical and Laboratory Standards Institute criteria, and whole-genome sequencing was used to identify resistance genes, virulence-associated traits, plasmid replicons, phylogroups, sequence types, and ST131 subclades. All isolates were multidrug resistant and showed high resistance to ampicillin and cephalexin (13/13, 100%), ciprofloxacin (13/13, 100%), cefpodoxime (11/13, 84.6%), cefovecin (10/13, 76.9%), and ceftiofur (10/13, 76.9%). An extended-spectrum β-lactamase phenotype was observed in 9/13 isolates (69.2%). bla_CTX-M genes were detected in 7/13 isolates (53.8%) and bla_CMY-2 in 3/13 isolates (23.1%), whereas IncF-associated plasmid replicons predominated. The isolates belonged to diverse lineages, including ST131, ST744, ST1196, and ST1011. The two ST131 isolates belonged to phylogroup B2, carried bla_CTX-M variants, and were assigned to the C2/H30Rx and C1-M27 subclades. These findings support further consideration of companion animals in genomic antimicrobial resistance surveillance under a One Health framework. Full article

Empirical management of acute pyelonephritis in Eastern Europe is increasingly constrained by extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and by uropathogen phenotypes—such as strong biofilm formation—which may further blunt antimicrobial activity. We aimed to characterise resistance mechanisms, minimum inhibitory concentration (MIC) distributions, biofilm-forming capacity, and the in vitro performance of carbapenem-sparing agents and to test whether these microbiological features improve prediction of clinical failure beyond standard bedside risk scores. We retrospectively analysed 102 Enterobacterales isolates recovered from 129 consecutive culture-confirmed adult pyelonephritis admissions at “Victor Babeș” University Hospital, Timișoara (March 2022–March 2025). MIC values were determined by Vitek 2 and interpreted using EUCAST v13 breakpoints; ESBL, AmpC, and carbapenemase phenotypes were confirmed by combination disk and modified carbapenem inactivation methods. Biofilm formation was quantified by the microtiter-plate crystal-violet assay. Mediation, Restricted Mean Survival Time (RMST), and decision-curve analyses were used to assess added clinical value. ESBL was confirmed in 30/102 (29.4%) isolates, AmpC in 9 (8.8%), and carbapenemase in 4 (3.9%). ESBL+ isolates were more often strong biofilm formers (33.3% vs. 12.5%; p = 0.014) and showed a 4- to 16-fold rightward MIC shift for cefepime, piperacillin–tazobactam, and ciprofloxacin. Among carbapenem-sparing agents, ceftazidime–avibactam (96.7% S), fosfomycin (80.0% S), and amikacin (73.3% S) retained the highest activity against ESBL+ isolates. Strong biofilm formation and the ESBL phenotype were independently associated with worse outcomes (adjusted OR 3.5 and 4.7); an exploratory mediation analysis suggested that biofilm formation may explain part of the observed association between the ESBL phenotype and treatment failure and that delayed effective therapy may account for a further portion of this association. A microbiology-enhanced model that added the ESBL phenotype, biofilm strength, and acquisition setting to routine clinical variables improved discrimination over a clinical-only baseline (AUC 0.89 vs. 0.71) and showed a higher net benefit on exploratory decision-curve analysis across the 10–40% threshold range. These predictive findings derive from a single-centre cohort with a small number of events and were only internally validated; they require validation in independent cohorts before any clinical application can be considered. The ESBL phenotype and strong biofilm formation were each independently associated with worse outcomes in pyelonephritis and may help identify candidate isolates for carbapenem-sparing strategies anchored on ceftazidime–avibactam, fosfomycin, and amikacin; given the observational, single-centre design, these associations should be regarded as hypothesis-generating. Full article

Pharmaceutical and microbial pollution in urban rivers is an emerging concern, particularly in developing regions with limited wastewater treatment capacity, posing risks to human health and ecosystems. This study evaluated the risk profiles of selected pharmaceutical compounds and bacterial indicators in the Sand River, South Africa, and computed their ecological risks, antimicrobial resistance (AMR), and human health risk assessment. Surface water samples were collected from three sites during the wet season and analyzed for target antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) using High-Performance Liquid Chromatography (HPLC) with a photodiode array (PDA) detector, while total coliforms (TCs) and Escherichia coli (E. coli) were enumerated using the Colilert system. Ciprofloxacin, sulfamethoxazole, and erythromycin were the most abundant pharmaceuticals, with maximum concentrations of 2.50 µg/L, 2.76 µg/L, and 2.53 µg/L, respectively. TC and E. coli levels exceeded regulatory thresholds, indicating severe microbial contamination. Risk quotient analysis identified ciprofloxacin, erythromycin, and trimethoprim as high-risk compounds for potential resistance selection (RQ ≥ 1), while ciprofloxacin and erythromycin posed significant ecological risks to fish. Although non-carcinogenic health risk assessment remained below concern (HI < 1), children showed higher exposure levels. These findings underscore the urgent need for improved pharmaceutical waste management and wastewater treatment infrastructure. Full article

Background/Objectives: The widespread presence of antimicrobial-resistant pharmaceutical contaminants in wastewater poses serious ecological and public health risks and remains difficult to address using conventional treatment technologies. Moreover, remediation strategies often involve overlooked environmental burdens, highlighting the need for technologies that are both efficient and environmentally sustainable. This study developed a novel GO/ZIF-60/CoNiAl -LTH (GO/ZIF-60/LTH) ternary nanocomposite adsorbent for removal of ciprofloxacin (CIP) from water matrixes while evaluating its environmental implications using Life cycle assessment (LCA). Methods: The adsorbent was synthesized by integrating graphene oxide (GO) and Ni–Al–Co layered triple hydroxide (LTH) into a ZIF-60 framework. Structural and surface characterization was conducted using XRD, FTIR, SEM–EDX, BET, and UV–Vis analyses. The adsorbent’s CIP aqueous uptake was evaluated through batch experiments supported by kinetic, isotherm, thermodynamic, and response surface methodology (RSM) analyses. Environmental performance was assessed through life cycle-based evaluation. Results: The composite achieved a maximum adsorption capacity of 291 mg g⁻¹ and 91.6% removal efficiency with adsorption following pseudo-first-order kinetics and the Freundlich isotherm. The process was spontaneous and exothermic, with 75% efficiency retained after three regeneration cycles. The LCA revealed an overall global warming impact of 0.953 kg CO₂ eq per functional unit, with the NiAlCo-LTH synthesis stage (1.04 kg CO₂ eq) as the dominant hotspot, followed by final composite formation stage (0.66 kg CO₂ eq). Adsorption and regeneration provided credits (−0.336 and −0.513 kg CO₂ eq), offsetting the upstream impacts. Conclusions: The study demonstrates a new MOF–GO–LTH hybrid adsorbent with high CIP removal efficiency combined with its environmental sustainability assessment, providing a more comprehensive basis for adsorbent evaluation. Although the NiAlCo-LTH component was primarily responsible for the enhanced adsorption performance, yet, it also constituted the major environmental hotspot during its synthesis. These findings highlight the relevance of trade-off between functionality and environmental burden for process optimization, cleaner production, and the sustainable development of advanced adsorbents for pharmaceutical-contaminated water treatment. Full article

Background/Objectives: Escherichia coli is the predominant pathogen in community-onset urinary tract infections (UTIs) requiring hospitalization. This study characterized antimicrobial resistance profiles, biofilm formation, extended-spectrum β-lactamase (ESBL) gene distribution, and phylogenetic background of E. coli isolates from hospitalized UTI patients in Western Mexico. Methods: Seventy isolates (September 2023–September 2024) underwent susceptibility testing (CLSI M100, 35th edition), multiplex PCR for blaTEM, blaCTX-M, and blaSHV genes, crystal violet biofilm quantification, and Clermont quadruplex PCR phylotyping. Associations were evaluated by Fisher’s exact test with Benjamini–Hochberg FDR (BH-FDR) correction. Results: ESBL phenotype and MDR were detected in 57.1% and 58.6% of isolates. After BH-FDR correction, ESBL production was significantly associated with amikacin (OR = 5.55; 95% CI: 1.80–18.74; q = 0.002) and TMP-SMX non-susceptibility (OR = 3.00; 95% CI: 1.02–9.23; q = 0.036); ciprofloxacin non-susceptibility was linked to MDR status (OR = 7.21; 95% CI: 1.28–75.66; q = 0.017) but not ESBL phenotype. Biofilm was detected in 77.1% of isolates. blaTEM predominated among ESBL producers (85.0%). Phylogroup B2 (51.4%) was inversely associated with recurrent UTI on both univariate (OR = 0.17; 95% CI: 0.03–0.73; p = 0.008) and adjusted analysis (adjusted OR = 0.19; 95% CI: 0.05–0.81; p = 0.025). Phylogroup C (22.9%) exhibited the highest MDR prevalence (81.3%) and the highest biofilm formation rate among phylogroups (87.5%). Conclusions: The high prevalence of ESBL-producing and MDR E. coli, combined with an unexpected predominance of blaTEM, reveals a distinctive local resistance landscape diverging from regional trends. The inverse association of phylogroup B2 with recurrence and TMP-SMX resistance reinforces the clinical value of phylogenetic surveillance in guiding UTI management strategies. Full article

Background/Objectives: Biofilms are a form of defense that enables bacteria to withstand antibiotic pressure and demonstrate antibiotic resistance. It is crucial to develop anti-biofilm strategies in order to combat chronic and persistent multidrug-resistant (MDR) infections. Methods: In this study, we developed 3D biofilms of single-, dual-, and poly-species MDR ESKAPE components, including the pathogens P. aeruginosa S. aureus and K. pneumoniae, in CF Mu3Gel. We evaluated the efficacy of using a phage, a di-hetero phage cocktail or a poly-hetero phage cocktail in combination with ciprofloxacin to eliminate mature biofilm biomass after 72 h or one week in a single treatment. Results: The phage components mostly exhibited synergistic behavior when combined with ciprofloxacin and with each other in di- and poly-hetero-cocktails. The reduction in 72-h dual- and poly-species biofilms was one log higher than that of one-week biofilms treated with the phage–antibiotic combination. The greatest reductions were observed in the 72-h single-species biofilm with combination therapy, at 1.4–3.0 log. Reductions of 2.16 and 1.6 log were observed in the dual-species P. aeruginosa and S. aureus biofilm and the poly-species biofilm, respectively. Conclusions: This study examined how a single application of phages or phage cocktails, either alone or in combination with ciprofloxacin, impacted established biofilm models, and how this affected the proportion of microcolonies of different species within each model. These insights will facilitate the development of strategies for multiple follow-up treatments, as well as the reordering of phages, phage cocktails, and combinations with antibiotics, to improve outcomes. The 3D biofilm models developed here could be used to screen phages or phage cocktails either on their own or alongside other therapies. This would facilitate the application of in vitro findings to real physiological settings. Full article

The rising threat of antimicrobial resistance necessitates the search for novel bioactive molecules from natural sources. This study investigated the phytochemical composition, antibacterial potency, and molecular docking interactions of Citrus aurantium peel ethanol extract against Escherichia coli outer-membrane and topoisomerase proteins and Staphylococcus aureus toxins as drug target proteins. Qualitative and quantitative phytochemical compositions were examined using standard analytical methods, chemical compounds were evaluated and qualified using Gas Chromatography–Mass Spectrometry (GC-MS), and antibacterial effects were investigated in silico and validated in vitro. Qualitative and quantitative analyses revealed high concentrations of flavonoids (4.54 ± 0.11%), alkaloids (1.6 ± 0.03%), terpenoids (1.35 ± 0.01%), tannins (1.02 ± 0.05%), phenols (0.97 ± 0.07%), and saponins (0.80 ± 0.01%). GC–MS profiling identified several dominant compounds, including β-D-glucopyranose, neo-inositol, 8-(2,3-dihydroxy-3-methylbutyl)-7-methoxy-2H-chromen-2-one, and D-allose. In silico docking studies against bacterial druggable proteins (PDB IDs: 4C56 and 3MFG, which are S. aureus toxins; 1BXW and 3FV5, which are E. coli outer-membrane and topoisomerase proteins) revealed strong binding affinities (−6.477 to −8.774 kcal/mol), comparable to standard antibiotics. ADMET predictions confirmed favorable pharmacokinetic and safety profiles, with most lead compounds displaying high intestinal absorption, low hepatotoxicity, and compliance with Lipinski’s rule of five. The extract exhibited stronger antibacterial activity, producing inhibition zones of 25.11 ± 0.017 and 23.04 ± 0.25 mm against clinical isolates of S. aureus and E. coli, respectively, at a concentration of 10 mg/mL, comparable to ciprofloxacin (30.35 ± 0.26 mm). These findings highlight C. aurantium peel phytoconstituents as promising scaffolds for antibacterial drug development and justify further in vivo validation for combating multidrug-resistant pathogens. Full article

Background/objectives: Infections caused by multidrug-resistant (MDR) bacteria are becoming increasingly difficult to treat with recommended antimicrobials. Considering the critical and growing challenge of antimicrobial resistance (AMR), this study aims to evaluate the antimicrobial susceptibility patterns of Escherichia coli clinical isolates from dogs in Grenada. This research project consists of two distinct studies: a retrospective analysis of AMR in canine E. coli isolates collected between 2010 and 2020, and a cross-sectional study characterizing the genotypic AMR profiles of E. coli isolates obtained between April and June 2023. Methods: A retrospective analysis of antibacterial sensitivity test (ABST) reports from canine clinical samples submitted to the Small Animal Clinic at St. George’s University (SGU), St. George’s, Grenada, between 2010 and 2020 revealed a notable prevalence of AMR among canine E. coli isolates. To further investigate the underlying mechanisms of this resistance, the study analyzed canine E. coli isolates that exhibited phenotypic resistance in ABST assays. These isolates were subsequently screened for AMR-associated genes using polymerase chain reaction (PCR) and next-generation sequencing (NGS). Results: The retrospective study identified 153 canine clinical isolates positive for E. coli. The antimicrobial drugs, imipenem, cefotaxime and ciprofloxacin were found to be highly effective against these isolates. However, a gradual increase in AMR was observed for amoxicillin–clavulanic acid (34.88%), ampicillin–sulbactam (17.31%), cephalexin (43.08%), cefpodoxime (22.31%), cephalothin (68.42%), and doxycycline (37.04%). In the prospective study, PCR analysis of resistant canine E. coli isolates detected the tetA (577 bp) and blaTEM (686 bp) genes. These AMR determinants were further confirmed through analysis of NGS reads and assembled contigs. Additionally, NGS-based predictions identified genes associated with resistance to aminoglycosides and potentiated sulfonamides. Conclusions: This study demonstrates that E. coli from dogs in Grenada exhibits resistance to tetracycline and several β-lactam antimicrobials. These findings underscore the need for rational antimicrobial stewardship and continuous AMR surveillance in small animal practice within the region. Full article