Search Results (126)

Klebsiella oxytoca has emerged as an important opportunistic pathogen in nosocomial infections, particularly during the COVID-19 pandemic, due to its capacity to acquire and disseminate resistance and virulence genes through horizontal gene transfer (HGT). This study presents a genome-based comparative analysis of K. oxytoca within the genus Klebsiella, aimed at exploring the evolutionary plausibility of outer membrane vesicle (OMV) associated processes in bacterial adaptation. Using publicly available reference genomes, we analyzed pangenome structure, phylogenetic relationships, and the distribution of mobile genetic elements, resistance determinants, virulence factors, and genes related to OMV biogenesis. Our results reveal a conserved set of envelope associated and stress responsive genes involved in vesiculogenic pathways, together with an extensive mobilome and resistome characteristic of the genus. Although these genomic features are consistent with conditions that may favor OMV production, they do not constitute direct evidence of functional OMV mediated horizontal gene transfer. Instead, our findings support a hypothesis generating evolutionary framework in which OMVs may act as a complementary mechanism to established gene transfer routes, including conjugation, integrative mobile elements, and bacteriophages. Overall, this study provides a genomic framework for future experimental and metagenomic investigations into the role of OMV-associated processes in antimicrobial resistance dissemination and should be interpreted as a recently identified evolutionary strategy inferred from genomic data, rather than a novel or experimentally validated mechanism. Full article

Foodborne diseases remain a public health issue worldwide. Inadequate attention to food safety and hygiene increases the risk of opportunistic pathogens and resistant bacteria spreading to people through the food chain, leading to foodborne diseases. To investigate food safety in our region, this study aims to measure the prevalence of microorganisms on raw food materials randomly purchased from wet markets in Chiang Mai province, Northern Thailand. In this study, microbial cultures, identified by MALDITOF-MS techniques, were used to determine the microflora and antibiotic-resistance organisms on raw vegetables and fruit. Consequently, to confirm antibiotic resistance, the antimicrobial susceptibility techniques were performed. The results found no Salmonella enterica was detected on the overall food samples. For Proteus spp. detection, P. mirabilis were detected at 3.23% in cabbage, 3.57% in Chinese cabbage, and 6.67% in lettuce, while P. vulgaris were detected at 7.14% in Chinese cabbage and 3.57% in peppermint. No Proteus spp. was detected in basils, tomatoes and grapes. In addition, for antibiotic-resistance detection, only ESBL-producing Klebsiella oxytoca was detected in the raw tomato sample (3.57%). According to the study’s findings, people who participate in the food process should be aware of their food safety and hygiene. Full article

We report a rare case of Rhodotorula mucilaginosa fungemia with a suspected abdominal origin in a 73-year-old man with advanced haematological disease on fluconazole prophylaxis. The patient presented with febrile neutropenia caused by a jejunal microperforation. Despite broad-spectrum antibiotics, the fever persisted, and Rhodotorula mucilaginosa was isolated from blood cultures. High-dose liposomal amphotericin B achieved microbiological clearance and clinical improvement. The case was further complicated by coinfection with Aspergillus fumigatus and Klebsiella oxytoca. To our knowledge, this is one of the few reported cases of abdominal Rhodotorula fungemia, and the first described in the context of fluconazole prophylaxis. This report emphasises the importance of recognising Rhodotorula as a true pathogen and highlights the challenges of managing rare fungal infections in immunocompromised hosts. Full article

Background: Chronic and acute wounds are often colonized by polymicrobial biofilms, delaying healing and complicating treatment. Rapid, non-invasive detection of pathogenic bacteria is therefore crucial for timely and targeted therapy. This study investigated porphyrin-producing bacterial species using the handheld cureVision imaging system. Methods: In this study, 20 clinically relevant, porphyrin-producing bacterial species were cultured on δ-aminolevulinic acid (ALA)-supplemented agar and analyzed using the handheld cureVision imaging system under 405 nm excitation. Both Red-Green-Blue (RGB) and fluorescence images were acquired under ambient daylight conditions, and fluorescence signals were quantified by grayscale intensity analysis. Results: All tested species exhibited measurable red porphyrin-associated fluorescence, with the highest intensities observed in Klebsiella pneumoniae, Klebsiella oxytoca, Veillonella parvula, and Alcaligenes faecalis. A standardized detectability threshold of 0.25, derived from negative controls, enabled semi-quantitative comparison across species. Statistical analysis confirmed that the fluorescence intensities of all bacterial samples were significantly elevated compared to the control (Wilcoxon signed-rank test and sign test, both p < 0.001; median intensity = 0.835, IQR: 0.63–0.975). Conclusions: These results demonstrate that the cureVision system enables robust and reliable detection of porphyrin-producing wound bacteria, supporting its potential as a rapid, non-invasive diagnostic method for assessing wound colonization and guiding targeted clinical interventions. Full article

Mushrooms, renowned for their nutritional value and bioactive compounds, offer potential health benefits, including antioxidants and anti-aging properties. Aging, characterized by cellular and tissue decline, is often associated with autophagy dysfunction, a crucial cellular cleaning process. This study aimed to investigate the neuroprotective, hepatoprotective, and antimicrobial properties of extracts from four medicinal and edible mushrooms: Ganoderma lucidum, Hericium erinaceus, Pleurotus ostreatus, and Agaricus bisporus. The protein, total phenol, and flavonoid content of mushroom extracts were determined. Aging was induced with 120 mg/kg D-galactose and treated with 500 mg/kg mushroom extracts. The study evaluated liver enzyme levels, histopathological changes in liver and brain tissues, gene expression correlated to neurodegeneration (SEPT5-SV2B-ATXN2-PARK2), telomere length, and immunomodulatory and pro-inflammatory (IL-2-IL-4-IL-6) gene expression pathways. Additionally, the antimicrobial potential of mushroom extracts was assessed against several bacteria (Lysinibacillus odyssey, Lysinibacillus fusiformis, Klebsiella oxytoca, and Escherichia coli) using agar well diffusion and lowest minimum inhibitory concentration (MIC) methods. By exploring these diverse aspects, this study aimed to provide a foundation for a better understanding of the potential of mushrooms as natural neuroprotective, hepatoprotective, and antimicrobial agents and their potential applications in human health. Results indicated that all mushroom extracts effectively mitigated oxidative stress. Agaricus bisporus exhibited the highest protein and flavonoid content, and Pleurotus ostreatus displayed the highest phenolic content. Notably, Hericium erinaceus and Ganoderma lucidum extracts demonstrated significant neuroprotective and hepatoprotective properties against D-galactose-induced aging, as evidenced by histopathological examination. All extracts exhibited a significant decrease (p < 0.001) in liver function (serum levels of aspartate aminotransferase (GOT) and alanine aminotransferase (GPT)) and showed immunomodulatory and anti-inflammatory effects, characterized by upregulated IL-2 and IL-4 gene expression and downregulated IL-6 gene expression. Hericium erinaceus demonstrated the most pronounced upregulation (p < 0.001) of SEPT5, SV2B, and telomere length gene expression, suggesting potential anti-aging effects. Furthermore, all mushroom extracts displayed antimicrobial activity against the tested bacterial strains, except Hericium erinaceus, which exhibited antibacterial activity solely against E. coli. Agaricus bisporus exhibited the largest inhibition zones (22 ± 0.06 mm) against Lysinibacillus odyssey, while Hericium erinaceus displayed the largest inhibition zone against E. coli. The MIC value was observed with Agaricus bisporus extract against Lysinibacillus odyssey (1.95 ± 0.16 mg/mL). Lysinibacillus fusiformis exhibited the highest resistance to the tested mushroom extracts. These findings suggest that these edible and medicinal mushrooms possess a wide range of health-promoting properties, including neuroprotective, hepatoprotective, and antimicrobial activities. Further research is needed to fully understand the underlying mechanisms and optimize applications. However, our results provide a strong foundation for exploring these mushrooms as potential natural agents that promote overall health and combat age-related decline. Full article

Propolis, also known as bee glue, is a natural resinous mixture produced by Western honeybees and has long been recognized for its potential therapeutic properties. Recent research has focused on its diverse bioactivities, particularly its antimicrobial effects against a broad spectrum of microorganisms, including human but also animal pathogens. However, further investigation is required to fully elucidate the pharmacological properties and potential toxicity of propolis to support its broader application. This study investigated the antimicrobial efficacy and safety of an ethanol extract of Portuguese propolis collected from the Gerês region (G23.EE). The antimicrobial activity was assessed in vitro against both Gram-positive and Gram-negative bacteria associated with infections in companion animals, using the agar dilution method. To evaluate potential toxicity, the extract was administered via injection and topical application in an in vivo Galleria mellonella larval model, with health parameters monitored over a 96 hours period. The in vitro results showed that G23.EE was more effective against Gram-positive bacteria, including Staphylococcus spp. (e.g., S. felis, S. hominis, S. simulans, and S. pseudintermedius; MIC = 0.5 mg/mL) and Enterococcus faecium (MIC = 1.5 mg/mL), than against Gram-negative bacteria, such as Escherichia coli and Klebsiella oxytoca (MIC > 8.0 mg/mL). No significant adverse effects were observed in G. mellonella larvae following injection or brushing with propolis extract concentrations up to 8.0 mg/mL. Overall, these findings suggest that Portuguese propolis from Gêres is a promising, safe, and effective natural antimicrobial agent for targeting Gram-positive bacterial infections in companion animals. Full article

The southern pudu (Pudu puda) faces significant threats from anthropogenic activities and infectious diseases. Using whole-genome sequencing (WGS) and forensic microbiology research, we describe a triple bacterial co-infection in a southern pudu impacted by wildfire disasters. The deer presented infected burn wounds on the extremities and dog bite wounds in the lumbosacral region, from which a multidrug-resistant CTX-M-1-producing Escherichia coli sequence type (ST) ST224 and a Klebsiella oxytoca ST145 were isolated, respectively. The patient died 13 days after admission in a wildlife rehabilitation center. During the necropsy, a sample from intracardiac blood was collected, and WGS analyses confirmed systemic dissemination of an E. coli ST224 clone. The broad virulome (adhesins, invasins, toxins, and immune evasion genes) and resistome against beta-lactams (bla_CTX-M-1), aminoglycosides [aac(3)-IId, aph(3′)-Ia, aph(3″)-Ib, aph(6)-Id], macrolides [mph(A)], sulfonamides (sul2), trimethoprim (dfrA17), and fluoroquinolones (gyrA and parC mutations) of E. coli ST224 contributed to the treatment failure and death of the wild animal. Additionally, an oval nodule was identified in the abdominal cavity caused by Acinetobacter baumannii ST1365, the first WGS-confirmed report in wildlife. This study highlights the value of applying forensic microbiology and WGS to investigate and understand One Health pathogens threatening wildlife impacted by natural and anthropogenic disasters. Full article

Klebsiella oxytoca originating from shellfish Scapharca subcrenata contains a number of virulence-related genes. In this study, we investigated its pathogenicity using a murine intestinal infection model and predicted its antibacterial compounds and targets via molecular docking analysis. The results revealed that the intake of K. oxytoca 8-2-11 strain (10⁹ CFU/day) via oral gavage for 7 days reduced the average body weight of the mice. The bacterium was present in fecal samples but absent from blood, lung, and liver samples from the mice. The intake of K. oxytoca 8-2-11 significantly altered colon bacteriota, with reduced abundance of Firmicutes, Lachnospiraceae, Lactobacillaceae, Lactobacillus, and Lactobacillus murinus, and increased in Bacteroidota, Muribaculaceae, and Alistipes (p < 0.05). Forty-four bioactive compounds in Scutellaria baicalensis and Forsythia suspensa were screened for docking with 117 potential virulence factors (VFs) in K. oxytoca 8-2-11. The compound baicalin displayed higher binding affinity toward these VFs, with the lowest mean binding energy (−8.4 kcal/mol). Baicalin was able to bind to key VFs in biofilm formation and adherence/motility (e.g., Mrks and EcpA) via forming stable hydrogen bonds, π-stacking, and π-cation interaction. In vitro, baicalin inhibited the bacterial growth and biofilm formation. This study establishes the first murine infection model using aquatic animal-derived K. oxytoca, and it provides candidate antibacterial compounds and targets for control of K. oxytoca infections. Full article

Klebsiella pneumoniae carbapenemases (KPCs) are a group of class A β-lactamases of Gram-negative bacteria leading to difficult-to-treat infections. We evaluated the global epidemiology of KPC-producing Gram-negative clinical isolates. A systematic search of six databases (Cochrane Library, Embase, Google Scholar, PubMed, Scopus, and Web of Science) was conducted. Extracted data were tabulated and evaluated. After screening 1993 articles, 119 were included in the study. The included studies originated from Asia (n = 49), Europe (n = 29), North America (n = 14), South America (n = 11), and Africa (n = 3); 13 studies were multicontinental. The most commonly reported KPC-producing species were Klebsiella pneumoniae (96 studies) and Escherichia coli (52 studies), followed by Enterobacter cloacae (31), Citrobacter spp. (24), Klebsiella oxytoca (23), Serratia spp. (15), Enterobacter spp. (15), Acinetobacter baumannii complex (13), Providencia spp. (11), Morganella spp. (11), Klebsiella aerogenes (9), Pseudomonas aeruginosa (8), Raoultella spp. (8), Proteus spp. (8), and Enterobacter aerogenes (6). Among the studies with specific bla_KPC gene detection, 52/57 (91%) reported the isolation of bla_KPC-2 and 26/57 (46%) reported bla_KPC-3. The antimicrobial resistance of the studied KPC-producing isolates was the lowest for ceftazidime–avibactam (0–4%). Resistance to polymyxins, tigecycline, and trimethoprim–sulfamethoxazole in the evaluated studies was 4–80%, 0–73%, and 5.6–100%, respectively. Conclusions: The findings presented in this work indicate that KPC-producing Gram-negative bacteria have spread globally across all continents. Implementing proper infection control measures, antimicrobial stewardship programs, and enhanced surveillance is crucial. Full article

Urogenital infections contribute greatly to both hospital- and community-acquired infections. In Ghana, the prevalence of resistance to commonly used antibiotics is relatively high. This study sought to evaluate the antibiotic sensitivity of bacterial urogenital pathogens from patient samples in a regional and district hospital in the Volta Region of Ghana. A retrospective cross-sectional study was conducted using data obtained between January and December 2023 from Volta Regional Hospital and Margret Marquart Catholic Hospital. Bacteria were isolated from urine, urethral swabs, and vaginal swabs from 204 patients. Data on culture and sensitivity assays performed using the Kirby–Bauer disc diffusion method were extracted and analyzed using WHONET. The most prevalent organisms isolated from the samples from both facilities were Escherichia coli (24.9%), Staphylococcus aureus (21.5%), and Klebsiella oxytoca (8.8%). The isolates were mostly resistant to amoxicillin/clavulanic acid (n = 75, 95% CI [91.8–99.9]), meropenem (n = 61, 95% CI [87.6–99.4]), cefuroxime (n = 54, 95% CI [78.9–96.5]), ampicillin (n = 124, 95% CI [61.2–77.9]), and piperacillin (n = 43, 95% CI [82.9–99.2]). Multidrug-resistant (MDR, 70 (34.1%)), extensively drug-resistant (XDR, 63 (30.7%)), and pandrug-resistant (PDR, 9 (4.3%)) strains of S. aureus, E. coli, and Pseudomonas aeruginosa were identified from the patient samples. The study highlights the presence of high-priority resistant urogenital pathogens of public health significance to varied antibiotic groups. Full article

Plastic pollution remains a critical global environmental challenge, with conventional disposal methods contributing to ecosystem degradation. Simultaneously, energy scarcity affects numerous rural communities, limiting development opportunities. This study presents an innovative approach that integrates microbial fuel cells (MFCs) with Klebsiella oxytoca to simultaneously degrade plastic waste and generate bioelectricity. The monitoring results over 40 days revealed optimal performance on day 28, with a peak voltage of 0.714 ± 0.026 V and an electric current of 3.149 ± 0.124 mA. The biocatalyst exhibited an electrical conductivity of 140.466 ± 5.180 mS/cm and an oxidation-reduction potential of 109.519 ± 5.35 mV, indicating efficient electron transfer. Furthermore, the MFCs achieved a maximum power density of 11.391 ± 0.814 mW/cm² with a current density of 5.106 mA/cm², demonstrating their potential for sustainable energy production. Fourier transform infrared (FTIR) analysis confirmed structural modifications in the plastic, with decreased vibrational peaks indicative of polymer degradation. Additionally, scanning electron microscopy (SEM) micrographs revealed porosity and surface cracks, highlighting Klebsiella oxytoca’s biodegradation capacity. These findings establish the viability of bioelectrochemical systems for simultaneous waste remediation and renewable energy generation, paving the way for scalable applications in environmental biotechnology. By coupling microbial degradation with electricity production, this research supports the development of sustainable solutions aligned with the principles of circular economy and climate change mitigation. Full article

Background: Chronic rhinosinusitis (CRS) affects 5.5–28% of the population and is primarily an inflammatory disease, with microbiota potentially playing a key role. Understanding microbial pathogens and resistance patterns is crucial for effective management. This study aimed to evaluate the incidence of Gram-negative rods in CRS in adults as a part of a prospective microbiological study. Methods: Over one year, paranasal sinus mucosa samples from CRS patients and nasal concha samples from controls were analyzed. Cultivable bacterial flora was assessed using culture-based methods. Biofilm formation was evaluated via a microtiter-plate assay, and antibiotic susceptibility was tested using the disk diffusion method. Results: Tissue samples from 74 CRS patients and 47 controls yielded 198 bacterial strains. Gram-positive cocci dominated, while Gram-negative rods accounted for 17.6%, with Escherichia coli, Klebsiella oxytoca, and Citrobacter spp. being most common. All Gram-negative rods formed biofilms in vitro. They were susceptible to cefotaxime, aztreonam, ciprofloxacin, and meropenem but showed varying sensitivity to ampicillin (20–67%), tigecycline (40–57%), and amoxicillin/clavulanic acid (73–83%). Conclusions: The result of this study underlines that treatment of CRS should be based on the result of drug susceptibility testing of the isolated microorganism. Full article

This study examines temporal patterns in pathogens isolated from prosthetic joint infection (PJI) cases and antimicrobial resistance patterns at a Romanian orthopedic center. We have conducted a retrospective cohort study that included 674 patients undergoing hip or knee replacement revision surgery between January 2016 and December 2023. From these, 102 confirmed PJI cases requiring surgical intervention were selected for analysis. We isolated 27 microorganisms from acute PJI cultures and 82 from chronic PJIs. Staphylococcus epidermidis (33 cases, 30.3%; 95% CI 22.0–40.3) was the predominant pathogen, with coagulase-negative Staphylococci (22 cases, 20.18%; 95% CI 0.9–41.3) and Enterobacteriaceae (13 cases, 11.9%; 95% CI 6.4–18.3) also prevalent. Methicillin resistance was identified in 43.6% of coagulase-negative staphylococci and 45.5% of Staphylococcus aureus isolates. All Gram-positive isolates remained susceptible to vancomycin, linezolid, and tigecycline. Among Gram-negative bacilli, Klebsiella oxytoca and Proteus mirabilis showed resistance to third-generation cephalosporins, with phenotypic profiles suggestive of extended-spectrum β-lactamase (ESBL) production. All Escherichia coli, Enterobacter spp., and Citrobacter freundii strains were fully susceptible to tested agents, while Pseudomonas aeruginosa exhibited reduced susceptibility to ciprofloxacin, aztreonam, and imipenem. Among the isolated strains, 47 were multidrug-resistant (MDR), with Staphylococcus aureus accounting for the highest MDR count, including methicillin resistance. The distribution of microorganism types and MDR strains remained consistent throughout the study period, with no significant association between infection type and MDR strain presence or between infection site and microorganism presence except for a strong association between MDR strains and the type of microorganism (p < 0.05). The microbial profile and resistance patterns in PJIs have remained stable over eight years. Our observations do not suggest that MDR PJIs are more commonly acute cases, contrary to what has been highlighted in previous reports. The ongoing prevalence of MDR strains underscores the importance of targeted antimicrobial treatments based on local susceptibility profiles. Full article

Background: Antimicrobial resistance (AMR) is a global threat in the public healthcare sector. The emergence of carbapenem-resistant Enterobacterales (CRE) has become a serious public health threat in South Africa. The spread of CRE has led to the use of colistin for treating severe infections. Colistin is a cationic, lipopeptide antibacterial agent that is effective against most Gram-negative bacteria through its disruption of the bacterial cell membrane. This study aims to determine the colistin resistance (MIC) and mobile colistin resistance (mcr-1) gene in clinical isolates from healthcare facilities in Mthatha and its surrounding areas. Methods: Fifty-three CRE isolates were collected from health facilities between January 2019 and June 2021 and stored in skim milk 10% and 5% inositol broth. The carbapenemase confirmatory test involved a RESIST-4 O.K.N.V assay (Coris BioConcept, Gembloux, Belgium), which was conducted following manufacturer protocol. Broth microdilution was performed according to the ISO standard method (20776-1) using A ComAspTM colistin 0.25–16 μg/mL MIC Broth. Conventional polymerase reaction (PCR) was performed for the detection of mcr-1. Results: N = 53 (100%) isolates were used. A total of 53% were defined as Klebsiella pneumoniae, Escherichia coli constituted 8%, Enterobacter cloacae 8%, Serratia marcescens 8%, Serratia fonticola 2%, Enterobacter aerogenes 2%, Klebsiella oxytoca 2%, Citrobacter koseri 2%, and Citrobacter freundii 2%. The specimens were from the following wards: Pediatric and Neonatal 38%, Medical 30%, Gynecology, Labour, and Maternity 11%, OPD and A&E 11%, ENT 4%, and Others—Male TB ward, Trauma, and adult ICU 6%. In total, 13% of the isolates were resistant and 86% were sensitive to colistin. The common CRE genes detected were OXA-48 at 47%, NDM at 13%, VIM at 1%, and a combination of OXA-48 and NDM at 5%. Of the isolates, 66% were positive for the production of carbapenamase. In this study, we found that all N = 53 (100%) isolates did not have the mobile colistin resistance gene (mcr-1). Conclusions: Antimicrobial resistance is associated with the emergence of carbapenemases genes. Increasing resistance to colistin in clinical settings can lead to difficulties in treating CRE infections, which may lead to clinical failure. In our study, 13% of isolates were phenotypically resistant to colistin. Full article

Background/Objective: Late-onset sepsis (LOS), a systemic infection occurring after 72 h of life, is a significant issue of morbidity and mortality in preterm neonates. Nevertheless, in this population, cultures frequently remain negative, even in the presence of typical clinical signs of sepsis. Materials and Methods: This single-center, retrospective study included preterm infants with a birth weight (BW) < 1500 g and/or a gestational age (GA) ≤ 32 weeks, diagnosed with culture-negative LOS (CNLOS) and culture-proven LOS (CPLOS). The study aimed to determine the incidence of these conditions, describe the frequency of isolated pathogens, and compare clinical profiles, antibiotic usage, morbidity, and mortality between these two groups as well as a no-sepsis group. Results: Among 277 infants, 30 (10.8%) had CPLOS, 83 (30%) had CNLOS, and 164 (59.2%) had no sepsis. Significant differences were found between the groups regarding BW, GA, hospitalization duration, morbidity, and mortality (p < 0.001). CNLOS and CPLOS did not differ in terms of mechanical ventilation or central line use. However, CPLOS infants had a higher rate of thrombocytopenia (p < 0.001), inotrope use (p = 0.006), and mortality (p < 0.001) compared to CNLOS infants. The duration of antibiotic treatment was similar between groups [median DOT (IQR): 20 (14–33) vs. 20 (14–35), p = 0.935]. In the CPLOS group, Gram-negative pathogens were isolated in 42.4% of infants, with Klebsiella oxytoca being the most common; Gram-positive organisms in 36.3%; and fungi in 21.2%. Conclusions: LOS, whether culture-proven or not, was associated with neonatal morbidity and mortality. CPLOS was linked to a worse prognosis, while CNLOS was also frequently diagnosed and associated with increased antibiotic use in Neonatal Intensive Care Units (NICUs). Full article