Search Results (1,167)

Introduction: Silver nanoparticles (AgNPs) are widely utilized for their exceptional antimicrobial properties, but concerns persist regarding their environmental impacts, particularly in soil and water ecosystems. This study compared the effects of chemically and biologically synthesized AgNPs and ionic silver on bacterial communities commonly present in soil and the proliferation of antibiotic resistance in the soil ecosystem. Results and Discussion: Biologically synthesized AgNPs exhibited the strongest antimicrobial activity, significantly reducing bacterial populations within a day, and demonstrated minimal impacts on the development of antibiotic resistance in long-term. Notably, resistance to ampicillin was lower by 72% in comparison with a control after 90 days in the presence of biologically produced AgNPs, while resistance to tetracycline and kanamycin dropped to nearly negligible levels. In contrast, chemically synthesized AgNPs and ionic silver substantially increased antibiotic resistance in long-term, particularly to ampicillin and chloramphenicol, where resistance levels were 11 to 13 times higher than the controls, respectively. Chemically synthesized AgNPs caused a gradual rise in resistance, while ionic silver induced consistently elevated resistance throughout the study. Conclusions: These differences highlight the complex interplay between nanoparticle composition and bacterial adaptation. The findings suggest that biologically synthesized AgNPs are a promising environmentally friendly alternative, reducing bacterial resistance and mitigating the risks associated with silver-induced antibiotic resistance in soil ecosystems. They have greater potential for sustainable applications while addressing critical concerns about antimicrobial resistance and environmental safety. Full article

Antimicrobial resistance (AMR) poses a critical global health threat, driving the search for alternative treatments to conventional antibiotics. In this study, the antibacterial properties of honeybee venom (BV) and fungal Monascus purpureus red dye (RD) were evaluated against three multidrug-resistant bacterial pathogens. Extracts of BV and RD exhibited dose-dependent antibacterial activity against the three tested bacteria, with their strongest effectiveness against S. aureus (minimum inhibitory concentrations [MIC] = 3.18 and 6.315 μg·mL⁻¹, respectively). Although the three bacterial strains were resistant to the antibiotic ampicillin-sulbactam (10/10 µg), both extracts exhibited superior antibacterial activity against the three bacterial strains compared to five standard antibiotics, especially RD extract, which produced the largest inhibition zone (20 ± 0.20 mm) against S. aureus. The larger inhibition zones against S. aureus suggest its high sensitivity, whereas E. coli and E. faecalis exhibited smaller inhibition zones, indicating less sensitivity to BV and RD extracts. Differences in the inhibition zones suggest the variations in antimicrobial activity between the two extracts and their strain-specific effectiveness. Scanning electron microscopy (SEM) revealed that BV and RD extracts disrupted the bacterial plasma membrane, suggesting that the bioactive compounds penetrate the bacterial cell wall and alter its integrity. Furthermore, GC–MS-based analysis revealed that the chemical composition of BV and RD extracts exhibited highly diverse structures, including complex polycyclic systems, porphyrins, steroids, and esters. For instance, 42 metabolites were identified in the BV extract, which mainly were organic and metal–organic compounds; however, only 23 molecules were identified in RD extract, which mainly were fatty acids and their derivatives. The diversity in the chemical compositions of both extracts highlights their potential applications in pharmaceuticals, materials, and biochemistry fields. Collectively, these findings indicate that honeybee venom and the red dye from M. purpureus have promising antibacterial properties and warrant further investigation as potential alternatives to conventional antibiotics. Further multi-ligand docking-based virtual screening studies are required to identify the most promising detected metabolite(s) within both BV and RD extracts. Full article

Ventriculo-meningitis or nosocomial meningitis/ventriculitis is a severe nosocomial infection that is associated with devastating neurological sequelae. The cerebrospinal fluid isolates associated with the infection can be Gram-positive or -negative, while the Enterococcus spp. is rarely identified. We report a case of a 68-year-old woman with a past medical history of insulin-dependent diabetes mellitus, hypertension, and coronary artery disease. She was admitted to the intensive care unit following a scheduled sphenoid wing meningioma resection. Her course was complicated with left middle cerebral artery pseudoaneurysm and hemispheric hemorrhage, and an arterial stent and external ventricular drainage catheter were placed. Neurological evaluation showed a minimal conscious state. She presented high fever on the 35th intensive care unit day. Cerebrospinal fluid was sampled and the external ventricular catheter was removed. Enterococcus faecalis was isolated from the culture specimen. The patient received targeted treatment with an ampicillin plus ceftriaxone combination, and a follow-up culture confirmed the pathogen’s eradication. Although she was considered cured, she had a prolonged intensive care unit stay and finally died in the ward two months after the completion of treatment. This case highlights the first reported use of this combination in a severe, non-endocarditis, invasive enterococcal infection, while the review discusses treatment options for nosocomial ventriculitis/meningitis. Full article

Background: The increased prevalence of antibiotic resistance among Gram-negative bacteria presents a severe public health challenge, leading to increased mortality rates, prolonged hospital stays, and higher medical costs. In Greece, the issue of multidrug-resistant Gram-negative bacteria is particularly alarming, exacerbated by overuse of antibiotics and inadequate infection control measures. This study aimed to detect the prevalence of extensively drug-resistant (XDR) Gram-negative bacteria in a tertiary hospital in Western Greece over the last eight years from 2016 to 2023. Materials and Methods: In the present study, all Carbapenem-resistant (CR) Acinetobacter baumannii, K. pneumoniae and Pseudomonas aeruginosa. bloodstream isolates from patients hospitalized in the University General Hospital of Patras in Western Greece, from January 2016 to December 2023, were recorded. XDR strains were defined as non-susceptible to at least one agent in all but two or fewer antimicrobial categories (i.e., bacterial isolates remain susceptible to only one or two categories). The prevalence and distribution of these pathogens across different hospital wards and their susceptibility patterns to key antibiotics (aminoglycosides, trimethoprim-sulfamethoxazole, tigecycline, colistin, ampicillin-sulbactam, ceftolozane-tazobactam and ceftazidime-avibactam) were recorded. Results: A total of 1142 blood cultures growing carbapenem-resistant Klebsiella pneumoniae (CRKp), Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPsA) were studied. In the present study, we found an increased resistance of both A. baumannii and K. pneumoniae in colistin. Acinetobacter baumannii had colistin resistance rates between 8.4% and 49.3%, showing a stable increase during the study period. K. pneumoniae showed an increased colistin-resistance rate in 2022 and 2023 (46.8% and 31.2%, respectively) Regarding P. aeruginosa, amikacin was almost inactive with a rate 68.4% and 87.5% in 2020 and 2023, respectively. Of all CR isolates, 69.3% were extensively drug-resistant (XDR). Acinetobacter baumannii had the highest percentage of XDR isolates (34.3%), followed by K. pneumoniae (26.8%) and P. aeruginosa (8.1%). Most XDR pathogens were isolated from the ICU (73.4%), followed by the internal medicine units (64%) and surgical units (22%). Conclusions: The rate of antimicrobial resistance and extensive drug resistance is alarmingly high, which calls for strict surveillance, control measures, and antibiotic stewardship to prevent the development of further resistance. Full article

The changing epidemiological profile of invasive Haemophilus influenzae infections (IIHi) is noted in the post-vaccination era. The aim of this study was to characterize phenotypically and genotypically invasive Haemophilus influenzae (Hi) isolates detected in Tunisian pediatric patients. A retrospective study was conducted in the microbiology laboratory of the Children’s Hospital of Tunis over ten years (2013–2023). All IIHi cases were included. Molecular identification and serotyping were conducted through qPCR. Molecular typing and analysis of resistance genes were extracted from whole genome sequencing data. Fifty-three IIHi cases were collected. Children under five years old were the most affected (81%). Non-typable isolates (NTHi) were predominant (79%) followed by serotype b (17%) and serotype a (4%). Genetic diversity was observed, essentially among NTHi isolates. Resistance of Hi isolates to ampicillin, amoxicillin–clavulanic acid and cefotaxime (CTX) were 42%, 20% and 4%, respectively. Thirteen isolates (29%) produced a beta-lactamase and 14 carried the blaTEM-1 gene (kappa = 0.95). For non-enzymatic resistance, group 3 (n = 12) showed resistance to ampicillin. Groupe 4 (n = 9, NTHi) showed discordances with resistance to CTX. The emergence of resistance to CTX is concerning. Continuous surveillance through molecular tools in conjunction with phenotypic and clinical data is necessary to ensure better management of these infections. Full article

This study aimed to investigate the incidence of subclinical mastitis (SCM), the implicated pathogens, and their impact on milk quality in dairy sheep in Greece. Furthermore, we preliminarily evaluated infrared thermography and the application of AI tools for the early, non-invasive diagnosis of relevant cases. In total, 660 milk samples and over 2000 infrared thermography images were obtained from 330 phenotypically healthy ewes. Microbiological investigations, a somatic cell count (SCC), and milk chemical analyses were performed. Infrared images were analyzed using the FLIR Research Studio software (version 3.0.1). The You Only Look Once version 8 (YOLOv8) algorithm was employed for the automatic detection of the udder’s region of interest. A total of 157 mammary glands with SCM were identified in 122/330 ewes (37.0%). The most prevalent pathogen was staphylococci (136/160, 86.6%). Considerable resistance was detected to tetracycline (29.7%), ampicillin (28.6%), and sulfamethoxazole–trimethoprim (23.6%). SCM correlated with high total mesophilic count (TMC) values and decreased milk fat, lactose, and protein content. A statistically significant variation (p < 0.001) was identified in the unilateral SCM cases by evaluating the mean temperatures of the udder region between the teats in the thermal images. Finally, the YOLOv8 algorithm was employed for the automatic detection of the udder’s region of interest (ROI), achieving 84% accuracy in defining the ROI in this preliminary evaluation. This demonstrates the potential of infrared thermography combined with AI tools for the diagnosis of ovine SCM. Nonetheless, more extensive sampling is essential to optimize this diagnostic approach. Full article

Central nervous system (CNS) infections caused by SARS-CoV-2 are uncommon. This case report describes the clinical progression of a 92-year-old female who developed a persistent neuroinfection associated with SARS-CoV-2. The patient initially presented with progressive fatigue, catarrhal symptoms, and a fever (38.6 °C). Initial laboratory findings revealed hypoxemia (O₂ saturation 79.8%), acidosis (pH 7.3), an elevated C-reactive protein (CRP) level of 14.8 mg/L, and a high D-dimer level (2.15 µg/mL). Nasopharyngeal (NP) antigen and RT-PCR tests confirmed SARS-CoV-2 infection, and an NP swab also detected penicillin- and ampicillin-resistant Staphylococcus aureus. She was admitted for conservative management, including oxygen supplementation, IV fluids, and prophylactic anticoagulation. Subsequently, she developed neurological symptoms—lethargy, discoordination, and impaired communication—without signs of meningism. Cerebrospinal fluid (CSF) analysis identified SARS-CoV-2 RNA (Ct = 29) on RT-PCR, while bacterial cultures remained negative. Treatment was intensified to include 10% mannitol, dexamethasone, and empiric ceftriaxone. Despite these interventions, the patient remained somnolent, with a Glasgow Coma Scale (GCS) score of 10. Upon discharge, her GCS had improved to 14; however, she continued to experience lethargy and cognitive issues, commonly described as “brain fog”. Inflammatory markers remained elevated (CRP 23 mg/L) and repeat RT-PCR of CSF confirmed a persistent SARS-CoV-2 presence (Ct = 31). This case underscores the potential for SARS-CoV-2 to cause prolonged CNS involvement, leading to persistent neurological impairment despite standard therapy. Further research is essential to clarify the pathophysiology of and determine optimal management for SARS-CoV-2 neuroinfections. Full article

Salmonella enterica is a globally important zoonotic microorganism that affects pigs and can enter the farm through various routes. This study aimed to determine the prevalence of S. enterica in water sources and pigs at Colombian pig farms, and to characterize the antimicrobial resistance of the isolates phenotypically and genotypically. Samples were collected from 103 farms including source water (n = 104), storage tank water (n = 103), drinking water (n = 103), and individual rectal swab samples (n = 1025). The presence of Salmonella was detected/identified using MDS-3M™ agar culture medium. Isolates were serotyped, and their antibiotic susceptibility was determined by minimum inhibitory concentration (MIC). Whole genome sequencing (WGS) was performed using Illumina NovaSeq, and bioinformatics analysis focused on serovar confirmation, MLST determination, and resistance gene detection. The overall between-farm prevalence of Salmonella enterica including all types of samples was 52.4% (54/103), with 6.4% of rectal swab samples and 21.3% of water samples found to be positive. Thirty serovars were identified using WGS, with the most common being S. Typhimurium var. monophasic (1,4,[5],12:i:-) (41.2%), S. Schwarzengrund (4.2%), and S. Saintpaul (4.2%). Salmonella Typhimurium and its monophasic variant were more commonly found in rectal swabs than the remaining serotypes (relative risk = 2.9, p < 0.0001), which were commonly found in the water samples (relative risk = 5.2, p < 0.0001). High levels of phenotypic resistance were observed, particularly to amikacin (99.2%), tetracycline (59.7%), chloramphenicol (55.5%), and ampicillin (42%). All isolates carried genes conferring resistance to aminoglycosides (aac(6′)-Iaa), quinolones (qnrB19), and tetracyclines (tetA). In conclusion, S. enterica is prevalent in Colombian pig farms including the water supply, with the S. Typhimurium monophasic variant being predominant, and antimicrobial resistance is widespread. Full article

This cross-sectional study assessed the prevalence, bacterial distribution, antimicrobial susceptibility, and potential risk factors associated with subclinical mastitis (SCM) in small-holder dairy herds in Gansu Province, Northwest China. Forty small-holder cow farms were randomly selected from eight cities/counties in six districts of Gansu Province, and a total of n = 530 lactating cows were included in this study. SCM prevalence was noted at 38.87% and 9.72% at the cow and quarter levels, respectively, based on the California Mastitis Test (CMT). The prevalence of the recovered bacterial species was noted as follows: S. agalactiae (36.02%), S. aureus (19.43%), coagulase-negative staphylococci (CNS) (16.11%), S. dysgalactiae (12.80%), E. coli (9.00%), and S. uberis (6.64%). All isolated bacteria were 100% multi-drug-resistant (MDR) except S. aureus (87.8% MDR). Antimicrobial susceptibility profiles revealed the increased resistance (>85%) of these pathogens to penicillin, streptomycin, trimethoprim–sulfamethoxazole, vancomycin, and erythromycin. However, these pathogens showed increased susceptibility to ampicillin, amoxicillin–sulbactam, ceftazidime, neomycin, kanamycin, spectinomycin, norfloxacin, ciprofloxacin, and doxycycline. The multivariate regression analysis demonstrated that old age, high parity, late lactation, lesions on teats, previous history of clinical mastitis, higher milk yield, and milking training were found to be potential risk factors (p < 0.001) associated with developing SCM in small-holder dairy cows in Gansu Province, China. These findings highlight the need for routine surveillance, antimicrobial stewardship, and effective preventive strategies to mitigate SCM in small-holder dairy production and their possible impacts, i.e., increased antimicrobial resistance and infection, on public health. Full article

Antibiotic susceptibilities, hemolytic activities, and technological properties of 46 Leuconostoc citreum isolates from kimchi were evaluated to select starter candidates. All strains were susceptible to clindamycin and erythromycin, while some exhibited resistance to ampicillin, chloramphenicol, gentamicin, streptomycin, and tetracycline; all were resistant to kanamycin based on the EFSA breakpoint values for Leuconostoc species. PCR analysis did not detect resistance genes for these six antibiotics in any strain. None of the strains demonstrated clear α- or β-hemolytic activity. All strains thrived in a medium supplemented with 6% NaCl, displaying protease activity and acid in media containing 6% and 3% NaCl, respectively. Consequently, five strains, AK5T17, AK5T19, AK10M04, DMLC16, and YK10T20, were identified as starter candidates, with L. citreum strain DMLC16 emerging as the top choice due to its elevated protease and acid production capacities. These findings support the safe application of L. citreum strain DMLC16 as a starter candidate in fermented food production. Full article

Single and dual-drug delivery systems (DDSs) based on linear choline polymers were designed through the controlled polymerization of a pharmaceutically functionalized monomer, i.e., [2-(methacryloyloxy)ethyl]trimethylammonium, with counterions of cloxacillin (TMAMA/CLX), or its copolymerization with [2-(methacryloyloxy)ethyl]trimethylammonium with ampicillin (TMAMA/AMP), providing antibiotic properties. This strategy was effective in attaining well-defined linear copolymers with 38–93 mol. % of TMAMA content, which were regulated by the initial ratio of TMAMA to methyl methacrylate comonomer. The polymer compositions were controlled by the total monomer conversion (40–75%), resulting in a variable degree of polymerization (DP_n = 160–300) and pharmaceutical anion contents (CLX⁻ 51–80% and AMP⁻ 78–87%). In aqueous solution, the polymers formed particles with sizes ranging between 274 and 380 nm for CLX⁻ systems and 288–348 nm for CLX⁻/AMP⁻ systems. In vitro drug release, driven by the exchange of pharmaceutical anions with phosphate ions in phosphate-buffered saline (PBS), imitating a physiological fluid, demonstrated release efficiencies of 58–76% for CLX⁻ (10.5–13.6 µg/mL) in single systems, and 91–100% for CLX⁻ (12.9–15.1 µg/mL) and 97–100% for AMP⁻ (21.1–23.3 µg/mL) in dual systems. Compared to conventional systems delivering antibiotics without a polymer carrier, the choline-based polymer DDS attained satisfactory levels of drug loading content and (co-)release from the polymer carriers, offering a promising alternative for antibiotic delivery. Full article

Community-acquired urinary tract infections (UTIs) represent a significant public health issue, primarily due to the increasing antibiotic resistance among uropathogens. This study assesses the resistance status of uropathogenic community Enterobacterales to various antibiotics, particularly aminoglycosides, and determines the prevalence of aminoglycoside-modifying enzyme (AME) genes, while investigating the coexistence of 16S rRNA methylating enzymes. We analyzed 628 clinical isolates of Enterobacterales obtained from 4282 cytobacteriological urine examinations at the Pasteur Institute Casablanca, Morocco, collected from October 2018 to December 2021. Identification and antibiotic susceptibility testing were conducted using the VITEK 2^® COMPACT system, following CA-SFM guidelines. DNA extraction utilized the heat shock method, and subsequent PCR was performed. Gram-negative bacteria accounted for 85% of isolates, with Enterobacterales representing 91% of this group. E. coli (73%) and Klebsiella pneumoniae (20%) were the most common species among Enterobacterales. Resistance was particularly high for ampicillin (76.7%) and amoxicillin-clavulanate (58%). Among aminoglycosides, gentamicin and tobramycin resistance rates were 33.5% and 35%, respectively, while amikacin resistance was observed in 21.3% of isolates. High frequencies of AME genes were detected, with AAC(3′)-IIa (27.7%) and AAC(6′)-Ib (25.9%) being the most prevalent. Notably, no 16S rRNA methylation genes (rmtA, rmtB, rmtC, rmtD) were found. All tested strains exhibited biofilm-forming capacity, with K. pneumoniae demonstrating intense biofilm production. The study highlights a concerning trend of antibiotic resistance among uropathogenic Enterobacterales in the community setting, correlating genotype with resistance phenotype and emphasizing the need for enhanced surveillance and targeted treatment strategies. Full article

Background: In hospital- and community-acquired central nervous system infections, resistant Gram-positive bacteria are an increasing therapeutic challenge. The present approach does not attempt to identify rapidly bactericidal therapies for susceptible pathogens but aims to improve methods to find antibiotic regimens for multi-resistant pathogens that are effective in vivo in spite of reduced in vitro susceptibility in culture media. Methods: Antibiotic susceptibility was tested in cerebrospinal fluid (CSF) and Mueller–Hinton broth (Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis) or brain–heart infusion (Streptococcus pneumoniae). Results: Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were either lower in CSF than in broth or equal in CSF and broth. The difference between MICs in CSF and broth was prominent with gentamicin, levofloxacin, linezolid (staphylococci), and vancomycin (staphylococci and pneumococcus), whereas it was absent with ampicillin (E. faecalis), penicillin G (S. pneumoniae), linezolid (enterococcus and pneumococcus), and vancomycin (enterococcus). In no case was the MIC or MBC higher in CSF than in broth. Conclusions: Several antibiotics possess an antibacterial effect in CSF at lower concentrations than the MICs determined in broth, i.e., MICs in broth underestimate in situ susceptibility in CSF. Full article

Multidrug-resistant (MDR) bacteria, especially Escherichia coli, are a major contributor to healthcare-associated infections globally, posing significant treatment challenges. This study explores the efficacy of (−)-epigallocatechin gallate (EGCG), a natural constituent of green tea, in combination with ampicillin (AMP) to restore the effectiveness of AMP against 40 isolated MDR E. coli strains. Antimicrobial activity assays were conducted to determine the minimum inhibitory concentrations (MIC) of EGCG using the standard microdilution technique. Checkerboard assays were employed to assess the potential synergistic effects of EGCG combined with AMP. The pharmacodynamic effects of the combination were evaluated through time-kill assays. Outer membrane disruption was analyzed by measuring DNA and protein leakage and with assessments using N-phenyl-1-naphthylamine (NPN) and rhodamine 123 (Rh123) fluorescence dyes. Biofilm eradication studies involved biofilm formation assays and preformed biofilm biomass and viability assays. Scanning electron microscopy (SEM) was used to examine changes in cellular morphology. The results indicated that EGCG demonstrated activity against all isolates, with MICs ranging from 0.5 to 2 mg/mL, while AMP exhibited MIC values between 1.25 and 50 mg/mL. Importantly, the EGCG-AMP combination showed enhanced efficacy compared to either treatment alone, as indicated by a fractional inhibitory concentration index between 0.009 and 0.018. The most pronounced synergy was observed in 13 drug-resistant strains, where the MIC for EGCG dropped to 8 µg/mL (from 1 mg/mL alone) and that for AMP to 50 µg/mL (from 50 mg/mL alone), achieving a 125-fold and 1000-fold reduction, respectively. Time-kill assays revealed that the bactericidal effect of the EGCG-AMP combination occurred within 2 h. The mechanism of EGCG action includes the disruption of membrane permeability and biofilm eradication in a dose-dependent manner. SEM confirmed that the combination treatment consistently outperformed the individual treatments. This study underscores the potential of restoring AMP efficacy in combination with EGCG as a promising strategy for treating MDR E. coli infections. Full article

The prevalence of foodborne diseases has raised concerns due to the potential transmission of zoonotic bacterial pathogens through meat products. The objective of this study was to determine the occurrence and antimicrobial resistance (AMR) profiles of pathogenic bacteria in cooked donkey meat products from Beijing. Twenty-one cooked donkey meat samples were collected from different delis, subjected to homogenization, and analyzed for bacterial contamination. Molecular identification was performed through polymerase chain reaction (PCR) amplification and sequencing targeting the 16S rDNA gene. The antimicrobial susceptibility of the isolates was evaluated using the disk diffusion method. A total of forty bacterial isolates were identified, with Proteus mirabilis being the predominant species, followed by Klebsiella pneumoniae and Novosphingobium. Both Proteus mirabilis and Klebsiella pneumoniae exhibited high levels of resistance to several antibiotics, including penicillin, ampicillin, and erythromycin. This study’s findings underscore the public health risk posed by antimicrobial-resistant foodborne pathogens and emphasize the necessity for enhanced food safety surveillance within the One Health context. Full article