Search Results (2,307)

Serratia species are opportunistic human pathogens found in diverse environmental habitats. Here, we report the first isolation of Serratia nevei from food samples in Nigeria. During a two-month epidemiological surveillance at a local food market in Dutsin-Ma, Katsina State, Nigeria, a total of 180 food samples were collected, and isolation and species identification were performed using chromogenic agar and MicroScan autoSCAN-4, respectively. Antimicrobial susceptibility and minimum inhibitory concentrations (MICs) were determined using the MicroScan autoSCAN-4 system. Strain F129B, recovered from a fresh, unprocessed beef sample, was initially identified as Klebsiella pneumoniae by chromogenic agar and MicroScan autoSCAN-4, and subsequently as Serratia marcescens by MALDI-TOF MS. Only Whole Genome Sequencing (WGS) and bioinformatics analyses confirmed its identity as S. nevei. The strain was then selected for further characterization by Whole Genome Sequencing (WGS) and bioinformatics analyses to confirm its identity. The strain was phenotypically resistant to amoxicillin/clavulanic acid and colistin, with elevated MICs for aztreonam (4 mg/L) and cefuroxime (16 mg/L). In silico analyses of its genome confirmed the isolate as S. nevei, harboring genes conferring resistance to β-lactams (blaSTR-2), aminoglycosides (aac (6′)-Ic), fosfomycin (fosA), streptomycin (satA), and tetracycline (tet (41)). Its virulence repertoire comprises genes associated with adhesion (yidE, yidR, yidQ), colicin tolerance (creA and creD), and heavy metal resistance (czcD, chrBACF operon). These findings underscore the need for genomic characterization for accurate species identification within the Serratia genus. Our findings revealed the emergence of S. nevei in the food supply chain and highlighted its potential for zoonotic transmission. Robust surveillance of the local food supply chain is urgently needed in north-western Nigeria. Full article

Carbapenem-resistant Klebsiella pneumoniae (CRKP) represents a critical global health threat, with ST101 identified as a major circulating clone in Saudi Arabia. We used whole genome sequencing and plasmid reconstruction to investigate the molecular characteristics of CRKP ST101 isolates from Saudi Arabia (2018–2021), analyzing antimicrobial resistance genes (ARGs), virulence factors, and plasmid structure and replicon types. Clinical isolates were obtained from the Ministry of National Guard Health Affairs (MNGHA) hospitals in Saudi Arabia between 2018 and 2021. Whole-genome sequencing was performed using the Illumina MiSeq^® platform, followed by comprehensive bioinformatic analysis of ARGs, virulence factors, and plasmid content. All ten isolates belonged to ST101 and harbored extensive antimicrobial resistance (AMR) and virulence determinants. Nine isolates (90%) carried bla_OXA-48, with three co-harboring bla_NDM-1, representing dual-carbapenemase producers. These carbapenemase genes were located on plasmids with distinct replicon types, including IncL/M, IncHI1B/IncFIB, and IncFIA/IncR. All isolates were multidrug-resistant (MDR), with half classified as extensively drug-resistant (XDR). Four isolates exhibited hypervirulent profiles, harboring aerobactin and yersiniabactin siderophores. This study provides comprehensive genomic characterization of CRKP ST101 in Saudi Arabia, revealing complex resistance mechanisms mediated by diverse plasmid types. The findings highlight the importance of genomic surveillance to track the evolution and dissemination of high-risk MDR and XDR lineages and inform targeted infection control strategies. Full article

Background and Objectives: Antimicrobial resistance is one of the most significant threats to modern healthcare, especially in intensive care units where ESKAPE pathogens—Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.—account for the majority of healthcare-associated infections. Romania is among the European countries with the highest rates of antimicrobial consumption and resistance. This study aimed to describe the epidemiological trends and antimicrobial resistance profiles of ESKAPE isolates over a four-year period (2021–2024) in a Romanian ICU (Intensive Care Unit). Materials and Methods: We conducted a retrospective observational study of all microbiological samples collected from adult ICU patients at the Clinical Emergency County Hospital of Sibiu between 2021 and 2024. Data were extracted from the electronic laboratory system and included patient demographics, specimen types, isolated microorganisms, and antimicrobial resistance classifications. Statistical analyses were performed using Python libraries, with significance set at p < 0.05. Results: A total of 801 infections were recorded, of which 562 (70.2%) involved ESKAPE pathogens. The predominant organisms identified were Klebsiella pneumoniae (42.8%) and Acinetobacter baumannii (36.0%), followed by Pseudomonas aeruginosa (11.2%). Nearly half of the isolates (47.3%) were multidrug-resistant, and 22.3% were extensively drug-resistant. Respiratory specimens, particularly tracheal aspirates, accounted for the majority of the isolates and exhibited the highest proportion of resistant phenotypes. A significant temporal increase in extensively drug-resistant isolates was observed over the study period (p < 0.05). Conclusion: ESKAPE pathogens remain the leading causes of ICU infections in Romania, with Klebsiella pneumoniae and Acinetobacter baumannii contributing significantly to the burden of multidrug- and extensively drug-resistant infections. Strengthening infection prevention strategies, optimizing antimicrobial stewardship, and implementing continuous microbiological surveillance are essential to mitigate the evolving resistance crisis in Romanian critical care settings. Full article

Evaluation of characteristics and flocculation mechanisms of microbial flocculants facilitates the identification of potential applications and informs the fine-tuning of operational conditions for maximum activity. Therefore, this study aimed to characterise and optimise the operational conditions of bioflocculants produced from Klebsiella pneumoniae and Meyerozyma guilliermondii for potent wastewater treatment. Scanning electron microscopy, X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) were employed to assess the surface morphology, crystalline structure, thermal stability, and functional group composition of the bioflocculants. Their cytotoxicity was assessed using the tetrazolium bromide-based assay against human colorectal adenocarcinoma (CaCO-2) cell lines. Flocculation efficiencies and mechanisms were determined using Jar and zeta potential assays, respectively. The bioflocculant from K. pneumoniae (Kp1) revealed a fibrous morphology, whereas that from M. guilliermondii (Mg1) displayed a granular structure. FTIR spectra revealed hydroxyl, amine, and alkene groups as key functional groups, while TGA analysis indicated that Kp1 was thermally unstable, contrary to Mg1, which exhibited good thermal stability. Bioflocculants Kp1 and Mg1 exhibited COD removal of 90.86% and 93.12% and turbidity reductions of 92.65% and 92.74%, respectively. Zeta potential analysis revealed that bioflocculant Kp1 primarily flocculated through charge neutralisation, while Mg1 employed a bridging mechanism. These bioflocculants illustrated strong potential to treat wastewater. However, the observed cytotoxic effect at increased concentrations warrants cautious handling and application in lower doses. Full article

Background: Multidrug-resistant (MDR) pulmonary infections represent a critical global health challenge, necessitating innovative therapeutic approaches. Green synthesis methodologies offer sustainable alternatives for nanoparticle fabrication while addressing antimicrobial resistance. Methods: Stimuli-responsive chitosan–silver hybrid nanoparticles (CS–Ag HNPs) were biosynthesized using Pseudomonas fluorescens bacterial extracts and loaded with ciprofloxacin for targeted pulmonary delivery. Comprehensive characterization included dynamic light scattering, transmission electron microscopy, UV–visible spectroscopy, and aerodynamic assessment via next-generation impactor. Antimicrobial efficacy was evaluated against MDR Pseudomonas aeruginosa and Klebsiella pneumoniae, including biofilm disruption studies, and biocompatibility was assessed. Molecular docking analysis elucidated binding mechanisms. Cytotoxicity and epithelial barrier integrity were evaluated using Calu-3 cell models. Results: The biosynthesized NPs exhibited optimal physicochemical properties (180 ± 20 nm, PDI 0.21 ± 0.04, ζ-potential + 32.4 ± 3.1 mV) with high encapsulation efficiency (68.2 ± 4.0%). Aerodynamic analysis revealed excellent inhalation characteristics (MMAD 2.6 μm, FPF 65 ± 5%). The hybrid system demonstrated 4-fold enhanced antimicrobial activity against MDR pathogens and significant biofilm disruption (70% for P. aeruginosa, 65% for K. pneumoniae) compared to free ciprofloxacin. Cell viability remained ≥85% at therapeutic concentrations. Molecular docking revealed enhanced drug-target binding affinity (−11.2 vs. −9.3 kcal/mol) and multi-residue interactions. Conclusions: Green-synthesized CS–Ag HNPs represent a promising sustainable platform for combating pulmonary MDR infections through enhanced antimicrobial efficacy and optimal aerodynamic properties. Full article

Milk contains wide microbial diversity, composed mainly of lactic acid bacteria (LAB), which are used as probiotics for both humans and livestock. We isolated, characterized, and evaluated LAB from indigenous Saudi Arabian camel milk to assess its probiotic potential, including antagonistic activity (against Methicillin-Resistant Staphylococcus aureus (MRSA) and Klebsiella pneumoniae), survivability in simulated gastric juice, tolerance to bile salts, cell surface hydrophobicity, auto- and co-aggregation, and antibiotic susceptibility tests. The two most promising LAB strains showed probiotic potential and were identified as Leuconostoc mesenteroides based on 16S rRNA gene sequences. These strains inhibited all pathogens tested to varying degrees and were resistant to kanamycin and vancomycin. None of the LAB cultures demonstrated hemolytic or gelatinase activity. Overall, the current data suggests that camel milk has substantial potential for introducing probiotics/LAB strains into the human food chain, making camel milk a potentially sustainable food. Full article

Endophytic fungi were isolated from ginger (Zingiber officinale) tubers and identified through molecular characterization of ITS and 28S rRNA regions. Nine species were obtained, belonging to the genera Aspergillus, Penicillium, Plectosphaerella, and Pseudogymnoascus. Several isolates, particularly Penicillium melinii, Aspergillus ustus, and Plectosphaerella cucumerina, exhibited strong antagonistic activity against Botrytis cinerea (up to 98.6% growth inhibition), while moderate effects were observed against Colletotrichum acutatum, Staphylococcus aureus and Klebsiella pneumoniae. All isolates produced at least one extracellular enzyme, with lipolytic and cellulolytic enzymes being the most frequently observed, and showed measurable antioxidant activity (EC₅₀ values ranging from 21.7 to 673.6 µg/mL). P. melinii and P. cucumerina demonstrated the highest radical scavenging capacities. These findings reveal the multifunctional potential of ginger-associated endophytic fungi as sustainable sources of bioactive compounds, with promising applications in biocontrol, food preservation, and industrial biotechnology. Full article

Background: The increasing worldwide problem of bacterial infections caused by multidrug-resistant Gram-negative and Gram-positive pathogens has led to consideration of intravenous fosfomycin, especially in combination antimicrobial regimens. We performed a systematic review of the evidence from comparative and non-comparative studies of patients who received intravenous fosfomycin as monotherapy or in combination with other antibiotics. Methods: Relevant studies were sought in six resources (Cochrane Library, Google Scholar, PubMed Central, PubMed, Scopus, and Web of Science) and two registries [ClinicalTrials.gov and International Clinical Trials Registry Portal (ICTRP)]. Results: Of the 2351 screened articles, 53 (31 comparative and 22 non-comparative studies) reported relevant data for patients with infections at various sites caused by Gram-negative bacteria, including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii, and Gram-positive bacteria, including Staphylococcus spp. and enterococci. Intravenous fosfomycin, either as monotherapy or combination therapy, showed similar or, in some studies, better efficacy (clinical and microbiological cure) compared to therapy with antimicrobial agents not including fosfomycin. The data evaluated also suggest that intravenous fosfomycin has a good safety profile. The administration of the antibiotic may be associated with electrolyte imbalances, especially hypokalemia and hypernatremia. These adverse events may be prevented and controlled with appropriate therapeutic measures and rarely lead to the discontinuation of the drug. Conclusions: Overall, the considerable body of published data suggests that intravenous fosfomycin is safe and effective. The antibiotic may be considered for patients with both Gram-positive and Gram-negative infections, especially in critically ill patients and/or deep-seated infections. The heterogeneity of the included studies is a limitation that prevents firm conclusions. Full article

Background: Carbapenem-resistant Enterobacterales (CRE) are designated by the World Health Organization as critical-priority pathogens. While global outcomes are well documented, regional data from the Middle East remain limited. Methods: We performed a retrospective cohort study of adults with confirmed CRE infections admitted to King Fahad Hospital of the University, Saudi Arabia, between 2019 and 2024. Clinical, microbiological, and therapeutic data were analyzed. Primary outcomes were infection recurrence, recurrence-related readmissions, and all-cause mortality at 14, 30, and 90 days. Predictors were assessed using univariate tests and multivariate Cox regression. Results: Among 101 patients (mean age 65 years, 57% female), Klebsiella pneumoniae predominated (94%), with OXA-48 detected in 70%. Most infections were hospital-acquired (78%). Recurrence occurred in 16.8% of cases, with 12.9% requiring readmission. Mortality reached 22.8% at 14 days, 30.7% at 30 days, and 42.6% at 90 days. Diabetes mellitus predicted recurrence (p = 0.024). Independent predictors of 90-day mortality were pneumonia (HR 2.39, 95% CI 1.23–4.64), critical care admission (HR 6.24, 95% CI 2.44–15.97), and hypotension (HR 4.10, 95% CI 1.84–9.15). Elevated Pitt bacteremia and INCREMENT-CPE scores also stratified risk. Conclusions: CRE infections in Saudi Arabia impose a heavy clinical burden, with high recurrence, frequent readmissions, and late mortality. Identifying drivers of recurrence and mortality highlights opportunities for targeted risk stratification. Beyond treatment choices, these findings emphasize the need for proactive surveillance, integrated stewardship, and early recognition of high-risk patients. Region-specific evidence such as this is critical to shaping infection control policies and guiding future multicenter research into novel therapeutic approaches. Full article

The gut microbiome regulates multiple physiological processes of the host and plays a significant role in the adaptation of wild animal hosts to extreme environments. The saxaul sparrow (Passer ammodendri) is a typical bird species found in the northwest of China, characterized by its strong adaptability to extreme environments. Studying it can help reveal the microbial adaptation mechanisms of the host to extreme environments. Therefore, we conducted a comparative analysis of the intestinal microbial community characteristics and functions of the saxaul sparrow in high-altitude (Pamir Plateau) and desert (Tazhong Town) habitats in Xinjiang. The results of full-length 16S rRNA sequencing and species annotation indicated that the bacterial species composition (relative abundance > 0.1%) of the intestinal microbiota community of the saxaul sparrow was Candidatus Arthromitus sp. SFB rat Yit, Escherichia coli, Enterococcus faecium, Enterococcus faecalis, and Klebsiella pneumoniae, in sequence. In addition, Lysinibacillus sphaericus is a unique strain specific to the Tazhong group, while Stenotrophomonas maltophilia has a much higher abundance in the Tazhong group than in the Pamir Plateau group. It is worth noting that both groups of samples contain potential opportunistic pathogenic bacteria, such as Escherichia coli and Klebsiella pneumoniae. The Shannon index of the Pamir Plateau group was lower than that of the Tazhong Town group (p = 0.0026), indicating that the intestinal microbial diversity of the Pamir Plateau group was lower than that of the Tazhong Town group. However, there was no significant difference in the ACE index between the two groups and it was not statistically significant (p > 0.05). The Beta diversity analysis revealed that the distance between the two groups of samples was considerable (p = 0.001), indicating a significant separation. The functional annotation results indicated that the Pamir Plateau group exhibited enhanced capabilities in carbohydrate metabolism, energy metabolism, and DNA damage repair, while the Tazhong Town group demonstrated enhanced lipid metabolism and detoxification abilities. These findings will help reveal the possible impact of the living environment on the composition and function of the intestinal microbiota of the saxaul sparrow, fill the gap in comparative studies of the intestinal microbiota characteristics of the saxaul sparrow in two extreme environments, and provide new theoretical support for subsequent related research. Full article

Antimicrobial resistance in healthcare-associated infections represents one of the greatest threats to global health. The COVID-19 pandemic disrupted infection control and antimicrobial stewardship, potentially affecting the prevalence of pathogens and the development of resistance. This study aimed to investigate the prevalence, antimicrobial resistance, and clonal dissemination of ESKAPE pathogens isolated from bloodstream infections during the second year of the COVID-19 pandemic in four tertiary-care hospitals in Mexico. A total of 926 isolates were analyzed: Staphylococcus aureus (22.4%), Klebsiella pneumoniae (22%), Acinetobacter baumannii (21.5%), Pseudomonas aeruginosa (12.5%), Enterobacter cloacae (9.4%), Enterococcus faecalis (8.4%), and Enterococcus faecium (3.8%). High rates of multidrug resistance were observed in A. baumannii (70.9% XDR) and K. pneumoniae (71% XDR plus MDR with 79% ESBL). P. aeruginosa and E. cloacae showed the highest susceptibility rates (53% and 48%, respectively) to all antimicrobials. The main β-lactamases involved in resistance were bla_SHV, bla_CTX-M, and bla_TEM in K. pneumoniae, while the predominant carbapenemases were bla_OXA-24, bla_OXA-23 in A. baumannii, bla_NDM in K. pneumoniae, and bla_VIM in P. aeruginosa. Among Gram-positives, methicillin-resistant S. aureus accounted for 33.8% of isolates, and vancomycin resistance was higher in E. faecium (28%) than in E. faecalis (1.3%). Pulsed-field gel electrophoresis revealed endemic circulation of A. baumannii clones (Pulsotypes 1AC, 2AM), persistent for over a decade, and interhospital dissemination of S. aureus and K. pneumoniae clones. These findings underscore the epidemiological relevance of MDR ESKAPE pathogens during the COVID-19 pandemic and highlight the urgent need to optimize empirical therapy and maintain continuous genomic surveillance to enhance infection control in Mexican hospitals. Full article

Subclinical mastitis (SCM) is one of the most common and detrimental diseases affecting dairy cows, causing lower milk yield and quality. Identification of pathogenic bacteria of subclinical mastitis (PSM) in dairy cows is crucial for selecting suitable antibiotic treatments and implementing effective prophylactic measures. This paper highlights the first systematic study to investigate the PSM in buffalo farms in Guangxi, China. It also analyzes the antibiotic resistance and virulence characteristics of typical PSM. The bacteriological characteristics of 132 milk samples collected from buffaloes with SCM across 3 representative buffalo farms in Guangxi, China were investigated. A total of 1659 bacterial strains were isolated and classified into 46 genera and 183 species, where 1058 bacterial strains were identified as PSM, representing 64% of the total isolates. The frequently isolated PSM in total samples were coagulase-negative Staphylococci (55.30%), Enterococcus faecalis (51.52%), Escherichia coli (31.82%), and Klebsiella pneumoniae (28.03%). All PSM strains showed multiple antibiotic resistance. Notably, E. faecalis and Lactococcus garvieae were resistant to all 12 antibiotics, whereas Staphylococcus chromogenes (95.24%), E. coli (89.19%), K. pneumoniae (83.87%), and Staphylococcus epidermidis (83.33%) were sensitive to levofloxacin (LEV). Additionally, E. coli exhibited the strongest mortality of Galleria mellonella. This study concluded that multiple PSM are present in the milk of buffaloes suffering from SCM in Guangxi, China. LEV may be a suitable antibiotic for the treatment of PSM. In the future, it is necessary to monitor the prevalence of PSM in buffalo farms and develop control strategies to prevent their spread. Full article

The production of β-lactamases is the main mechanism underlying carbapenem resistance. This study combined in silico and in vitro approaches to identify potential polyphenols as carbapenemase inhibitors. Molecular docking, molecular dynamics, and ADMET prediction were performed to assess the binding affinity, stability, and safety of quercetin, kaempferol, caffeic acid, and 3,4-dihydroxybenzoic acid against KPC-2, NDM-1, and OXA-48 carbapenemases. In vitro antibacterial assays and checkerboard analyses were conducted against Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa to assess antibacterial and synergistic effects. Then, the inhibition of the β-lactam hydrolytic activity was confirmed. In silico results showed that quercetin, kaempferol, and caffeic acid exhibited strong binding affinity and consistent stability towards the targets. Therefore, quercetin and kaempferol showed the strongest affinities (−8.0 kcal/mol) and stable interactions with key catalytic residues. ADMET profiles indicated good pharmacokinetic behavior and low acute toxicity. In vitro assays revealed that the polyphenols exhibited MIC values ranging from 12.5 to 25 mg/L and MBC values of 25–50 mg/L. Combined with cefotaxime, they enhanced bacterial susceptibility and inhibited β-lactam hydrolysis, with quercetin achieving complete inhibition at 200 mg/L. These findings highlight the potential of the four polyphenols as natural β-lactamase inhibitors. Further enzyme kinetics and in vivo studies are needed to confirm their therapeutic relevance. Full article

Klebsiella pneumoniae (K. pneumoniae) is a major nosocomial pathogen with increasing antibiotic resistance. Treatment failures and high mortality rates in sepsis caused by K. pneumoniae are associated with difficulties in choosing an adequate antibacterial therapy in the presence of resistance to all available antibiotics, based on the results of susceptibility tests. This study aimed to identify “weak points” in the metabolism of K. pneumoniae, to be able to use these features in the future. Ten nosocomial K. pneumoniae strains were incubated with fourteen broad-spectrum antibiotics representing major drug classes. Aromatic metabolites were analyzed using gas chromatography–mass spectrometry after 24 h exposure. Phenyllactic acid (PhLA), comprising 86% of detected phenylcarboxylic acids, served as the metabolic activity marker. Antibiotics demonstrated multidirectional effects on aromatic compound metabolism. Doxycycline, nitrofurantoin, rifampicin, and tigecycline significantly suppressed metabolic activity, confirmed by decreased PhLA levels. Conversely, meropenem, cephalosporins (ceftriaxone, cefepime, cefotaxime, and ceftazidime), ciprofloxacin, and amikacin stimulated PhLA production, suggesting that bacterial metabolic activity was maintained despite the presence of antibiotics. PhLA is a promising biomarker for quantifying K. pneumoniae’s metabolic response to antibiotics. This potentially introduces a novel approach for future investigations into resistance mechanisms and has the potential to increase the effectiveness of therapies for multidrug-resistant K. pneumoniae infections by providing an additional analytical tool to traditional susceptibility testing methodologies. Full article

Acinetobacter baumanni (A. baumannii) is a well-known pathogen associated with antimicrobial-resistant infections. It is a major cause of nosocomial infections and is frequently associated with polymicrobial and antibiotic-resistant infections. This study investigates the frequency of A. baumannii infections, its antimicrobial resistance profile and the main co-pathogens isolated in respiratory samples at the San Giovanni di Dio e Ruggi d’Aragona Hospital in 2015–2019 (pre-COVID-19 pandemic) and 2020–2023 (during/post-COVID-19 pandemic). Bacterial identification and antibiotic susceptibility testing were performed using the VITEK^® 2 system (2015–2019), while identification was carried out with MALDI-TOF MS starting from 2020. A total of 1679 strains were isolated between 2015 and 2019, and 1186 between 2020 and 2023, with significantly higher frequencies in males 61–80 and females 71–80. A. baumannii was isolated predominantly from respiratory specimens, derived predominantly in intensive care units (ICUs). The antimicrobial resistance rates of A. baumannii were above 90% for gentamicin, trimethoprim/sulfamethoxazole, imipenem and ciprofloxacin, while colistin resistance was less than 1% (0.95%) in pre-pandemic and alarmingly increased during/post pandemic period (6.1%). A. baumannii was most frequently associated with Klebsiella pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa in respiratory tract infections. A. baumannii represents a serious global health threat due to its extensive antimicrobial resistance, highlighting the need for continuous surveillance, detailed strain characterization, and development of new antimicrobial agents. Full article