Search Results (798)

Haemophilus influenzae type b (Hib) is a Gram-negative bacterium that causes severe infections in children under five, especially in developing countries. Although vaccination using capsular polysaccharide by Hib (linear polymer 5-D-ribitol-(1→1)-β-D-ribose-3-phosphate) conjugated to tetanus toxoid is effective, its production is complex and costly. This study aimed to develop a continuous production process for PRP to increase productivity, reduce batch numbers, and simplify manufacturing. Using a 1 L bioreactor, five dilution rates (0.13 to 0.32 h⁻¹) were tested, with the best performance observed at 0.23 h⁻¹, reaching a productivity of 167 mgL⁻¹·h⁻¹. Under optimized conditions, parameters such as free and immobilized PRP, glucose consumption, acetate formation, and biomass were monitored. The process yielded 874 mgL⁻¹ of PRP after 74.4 h, with 78% in the free form and a final productivity of 165 mgL⁻¹·h⁻¹, approximately six times higher than batch processes and twice as high as fed-batch processes. The continuous process proved more efficient and required less infrastructure to meet production demands. However, further optimization is needed to enhance product quality and assess overall feasibility. Full article

During four outbreaks in 2023 and 2024, samples from pond-reared Nile tilapia were taken from different farms located in Kafr Elsheikh governorate, Egypt. Samples were submitted for laboratory examinations. Diseased fish exhibited bacterial septicemia and some cases died without showing any clinical signs. A total of 30 bacterial isolates were isolated and identified. Of these isolates, 57% were identified as Gram-positive bacteria, whereas the remaining 43% were identified as Gram-negative bacteria. PCR targeting the 16S rRNA gene and genome sequencing confirmed five bacterial isolates as Aeromonas veronii (30%), Vibrio alginolyticus (13.3%), Enterococcus faecalis (23.3%), Aerococcus viridans (16.7%), and Staphylococcus epidermidis (16.7%). The NCBI GenBank accession numbers of these strains were (PV018985) for A. veronii, (PV016854) for V. alginolyticus, (PV013413) for E. faecalis, (PV032005) for A. viridans, and (PV012491) for Staph. epidermidis. The antibiogram revealed that the bacterial strains showed resistance to most of the antibiotics tested. A. viridans exhibited resistance to nearly all the antibiotics except for intermediate sensitivity to ciprofloxacin and amoxycillin/clavulanic acid. However, A. veronii showed high sensitivity to amoxycillin/clavulanic acid, oxytetracycline, kanamycin, and trimethoprim/sulfamethoxazole and intermediate susceptibility to ciprofloxacin. Similarly, E. faecalis showed high susceptibility to amoxycillin/clavulanic acid, ciprofloxacin, and trimethoprim/sulfamethoxazole in addition to intermediate sensitivity to ampicillin and kanamycin. Furthermore, Staph. epidermidis strain was highly susceptible to ampicillin, amoxycillin/clavulanic acid, oxytetracycline, novobiocin, and trimethoprim/sulfamethoxazole and was partially sensitive to kanamycin and ciprofloxacin. To conclude, summer mortalities recorded in farmed tilapia were closely related to a multifactorial bacterial origin with different sensitivity to antibiotic discs. Full article

Background/Objectives: Streptococcus uberis is a Gram-positive bacterium and a major cause of bovine mastitis. The use of antimicrobial treatments raises concerns about resistance. This study aimed to characterize S. uberis isolates from one of the ten largest milk-producing regions in Europe. Methods: Thirty-six isolates from 36 cows with mastitis were identified using MALDI-TOF and VITEK^®MS. Susceptibility to 9 antibiotics (penicillin G, ampicillin, tetracycline, erythromycin, clindamycin, cefotaxime, ceftriaxone, levofloxacin, and moxifloxacin) was determined with VITEK^®2. Whole-genome sequencing was performed using MinION Mk1C. Results: Alleles were identified for 7 loci: arcC, ddl, gki, recP, tdk, tpi, and yqiL. Only 10 isolates had alleles for all the loci. The loci with the highest number of alleles were ddl and tdk (33/36 strains), while arcC had the fewest (19/36). Four isolates were assigned to known sequence types (ST6, ST307, and ST184), and novel alleles were detected in 32 of the 36 isolates. Twelve isolates showed phenotypic resistance to one or more of the following antibiotics: tetracycline, erythromycin, clindamycin, and ceftriaxone. The lnu was the most frequently detected resistance gene (27 out of 102 total gene appearances). A total of 19 virulence factors were identified. All strains were predicted to be capable of infecting human hosts. Conclusions: Streptococcus uberis is a potential reservoir of antimicrobial resistance genes. The use of antimicrobials to treat bovine mastitis has reduced the susceptibility of this microorganism to several antibiotics, underscoring the importance of monitoring antimicrobial use in veterinary practice. The results also highlight the high genetic diversity of the isolates, suggesting a strong capacity to adapt to different environmental conditions. Full article

Background: Despite efforts to rely on arteriovenous fistulas/grafts for maintenance hemodialysis, a significant number of patients still depend on tunnel hemodialysis catheters for treatment. This poses a risk factor for central line-associated bloodstream infection (CLABSI) and, subsequently, vascular access compromise. Method: We conducted a retrospective study in five dialysis centers to determine the potential factors resulting in vascular access loss, CLABSI incidence, and microbe distribution patterns in Saudi Arabia at centers under the Ministry of National Guard Health Affairs. Adults who regularly received hemodialysis and had positive blood cultures between January 2019 and December 2023 were the subjects of the study. Results: Our study identified the presence of tunnel infection (p < 0.001), the presence of a Gram-negative pathogen (p = 0.036), and a high body mass index (BMI > 30) (p = 0.04) as potential risk factors leading to the loss of tunnel central venous catheters. In contrast, there was a lower probability of central venous catheter loss due to Gram-positive pathogens (p = 0.01). The CLABSI rate was 1.55 per 100 patients per month over a five-year period. Patients with CVC required more hospital treatment and had a significantly higher rate of vascular access loss (p < 0.001). Both central and peripheral blood cultures had nearly identical microbe spectra. Methicillin-sensitive Staphylococcus aureus (MSSA), Methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus epidermidis had the highest prevalence rates among Gram-positive organisms. Among the Gram-negative bacteria, Enterobacter cloacae was the most common, followed by Klebsiella pneumonia and Pseudomonas aeruginosa. Conclusions: Our findings indicate the need for rigorous measures and interventions to prevent Gram-negative infections and decrease the reliance on central venous catheters, to decrease infections in hemodialysis patients, and decrease morbidity and cost. Strict hand hygiene, patient education, and surveillance programs are recommended to monitor these patients. Full article

Introduction: Linezolid is a reserve antibiotic used to treat infections caused by Gram-positive bacteria with resistance genes. In critically ill patients, high intra- and interindividual variability has been observed, prompting the search for alternative methods to reduce this variability and achieve the pharmacokinetic/pharmacodynamic indices necessary for a favorable efficacy–safety balance. Aim of the study: We wished to compare the safety and effectiveness of a continuous infusion (CI) versus an intermittent infusion (II) of linezolid in patients requiring intensive care. Materials and Methods: This study, registered under the number NCT05801484), was a prospective, open-label, single-center, two-arm study. Data on hematologic safety and effectiveness were collected and compared between patients receiving CI and II, respectively, at the same daily dose of linezolid (1200 mg). Results: Twenty-nine patients from the intensive care unit were included, divided into two groups. No statistically significant difference was found in 30-day mortality between the groups, nor in the likelihood of post-treatment culture negativity. However, a significantly greater reduction in C-reactive protein levels was observed in the CI group compared to the II group. Regarding safety, at CrCl < 60 mL/min, the decrease in platelets was statistically significant in group II but not in group CI. Additionally, at the 30-day follow-up, recovery from thrombocytopenia was better in the CI group. Conclusions: Continuous infusion of linezolid proved to be non-inferior to intermittent infusion at the same daily dose in terms of effectiveness. Furthermore, a lower risk of adverse reactions was identified with continuous infusion. Full article

The rise in the number of cancer cases and the dissemination of strains with multiple drug resistance in the world pose a serious threat to public health care and human well-being. The design and study of new chemotherapeutic agents for cancer and infectious diseases are hot topics in science. Hydrazones, a versatile and diverse class of chemical compounds, gained a lot of attention as a promising base for future drugs. In this paper, we report on the synthesis of eight new gold(III) complexes with hydrazones derived from pyridoxal-5′-phosphate and pyridoxal. The complexes are thoroughly characterized using IR, ¹H, ³¹P NMR, and mass spectroscopy. The cytotoxic effect of twelve various hydrazones derived from pyridoxal 5′-phosphate on both immortalized (HEK293T) and tumor (HCT116) human cell lines was estimated using the MTT assay. In addition, this contribution describes the antibacterial action of complexes of gold(III) and pyridoxal and pyridoxal 5′-phosphate-derived hydrazones, as well as the mixtures of the solutions containing tetrachloroaurate(III) and hydrazones, using the zone of inhibition test. Gold(III) complexes exhibit moderate antibacterial activity against both Gram-positive and Gram-negative bacteria, while free hydrazones show low cytotoxicity and thus could be considered relatively safe for humans. Full article

Surgical site infections (SSIs) remain a significant complication in spine surgery, especially in instrumented procedures with long operative times. Although guidelines recommend cefazolin as the first-line agent due to its efficacy against Staphylococcus aureus, predictable pharmacokinetics, and safety, its real-world practice is highly variable, with inappropriate and prolonged regimens reported across Europe. Vancomycin is often used as the first choice of therapy empirically and without screening, exposing patients to risks such as delayed infusion, nephrotoxicity, and the emergence of vancomycin-resistant enterococci (VRE).This review assesses the present function of vancomycin in relation to cefazolin for spinal prophylaxis and examines wider trends in the misuse of surgical antibiotic prophylaxis, which were identified through PubMed and Scopus searches. Evidence from randomized and prospective studies consistently supports cefazolin as the preferred prophylactic agent in clean spinal surgery. Observational data suggest that adjunctive or topical vancomycin may reduce infection rates in selected high-risk or revision cases, though the results are inconsistent and frequently limited by retrospective designs and heterogeneous outcome reporting. Importantly, the most rigorous randomized controlled trial found no benefit of intrawound vancomycin over the placebo. A small number of available investigations in vancomycin use with major design limitations have resulted in no significant VRE emergency. Unexpectedly, widespread use of vancomycin was followed by a notable transition toward Gram-negative and opportunistic organisms. In summary, vancomycin may only be considered in patients with documented MRSA colonization, β-lactam allergy, or selected revision procedures, but its widespread empirical use as a first-choice therapy is not supported. Full article

The efficiency of in vitro regeneration in litchi (Litchi chinensis Sonn.) is highly influenced by the type and concentration of plant growth regulators (PGRs), particularly auxins. This study evaluated the effects of phenylacetic acid (PAA) and its derivatives—4-chlorophenylacetic acid (CPA) and 4-iodophenylacetic acid (IPA)—on callus proliferation, somatic embryogenesis, and plantlet regeneration in ‘Feizixiao’ litchi, as well as to establish an efficient regeneration protocol. The inclusion of CPA or IPA in callus proliferation medium significantly enhanced the proliferation rate, with 20 mg·L⁻¹ CPA being the most effective. The highest number of somatic embryos per gram of fresh embryonic callus weight (gFW⁻¹) (1131 embryos·gFW⁻¹) was observed with 40 mg·L⁻¹ PAA in proliferation medium. The addition of 10 mg·L⁻¹ IPA to the proliferation medium yielded the highest plantlet regeneration rate (50 plantlets·gFW⁻¹). Supplementing the somatic embryo induction medium with 5 mg·L⁻¹ PAA resulted in 460 somatic embryos·gFW⁻¹ and 86 regenerated plantlets·gFW⁻¹. These findings indicate that PAA and its derivatives are effective PGRs for the in vitro regeneration of litchi, providing a valuable protocol for the propagation of elite cultivars. Full article

Photodynamic inactivation and antimicrobial photodynamic therapy (PDI/APDT) based on the toxic properties of reactive oxygen species (ROS), which are generated by a number of photoexcited dyes, are promising for preventing and treating infections, especially those associated with drug-resistant pathogens. The negatively charged bacterial cell surface attracts polycationic photosensitizers, which contribute to the vulnerability of the bacterial plasma membrane to ROS. The integrity of the plasma membrane is critical for the viability of the bacterial cell. Polycationic phthalocyanines are regarded as promising photosensitizers due to their high quantum yields of ROS generation (mainly singlet oxygen), high extinction coefficients in the far-red spectral range, and low dark toxicity. For application in PDI/APDT, the wide range of possibilities of modifying the chemical structure of phthalocyanines is particularly valuable, especially by introducing various peripheral and non-peripheral substituents into the benzene rings. Depending on the type and location of such substituents, it is possible to obtain photosensitizers with different photophysical properties, photochemical activity, solubility in an aqueous medium, biocompatibility, and tropism for certain structures of photoinactivation targets. In this study, we tested novel water-soluble Zn (II) phthalocyanines bearing four 4-((diethylmethylammonium)methyl)phenoxy substituents with symmetric and asymmetric charge distributions for photodynamic antibacterial activity and compared them with those of water-soluble octacationic zinc octakis(cholinyl)phthalocyanine. The obtained results allow us to conclude that the studied tetracationic aryloxy-substituted Zn(II) phthalocyanines effectively bind to the oppositely charged cell wall of the Gram-negative bacteria E. coli. This finding is supported by data on bacteria’s zeta potential neutralization in the presence of phthalocyanine derivatives and fluorescence microscopy images of stained bacterial cells. Asymmetric substitution influences the aggregation and fluorescent characteristics but has little effect on the ability of the studied tetracationic phthalocyanines to sensitize the bioluminescent E. coli K12 TG1 strain. Both symmetric and asymmetric aryloxy-substituted phthalocyanines are no less effective in PDI than the water-soluble zinc octakis(cholinyl)phthalocyanine, a photosensitizer with proven antibacterial activity, and have significant potential for further studies as antibacterial photosensitizers. Full article

Background/Objectives: Carbapenem-resistant Gram-negative bacilli (CR-GNB) pose a growing challenge to public health worldwide due to limited treatment options. This cross-sectional study investigated the characteristics of CR-GNB isolated from clinical specimens in Lagos, Nigeria. Methods: Gram-negative bacilli (GNB) and clinical data were obtained from three multi-specialist private hospitals between March and June 2023. The GNB were identified using the Analytical Profile Index (API) and investigated for CR-GNB by disk diffusion. Antimicrobial resistance patterns and carbapenemase gene data for presumptive carbapenemase-producing Gram-negative bacilli (CP-GNB) were analyzed using Vitek-2 and polymerase chain reaction (PCR). Results: Of 317 GNB, 29.0% (n = 92) were CR-GNB. Significantly higher numbers of CR-GNB were reported from the intensive care unit and oncology department (p = 0.009). Of all CR-GNB, 17 isolates (18.5%) were classified as presumptive CP-GNB. In this subgroup, resistance rates of ampicillin/sulbactam (100.0%) and trimethoprim/sulfamethoxazole (100.0%) were highest. Ten (10) CP-GNB were confirmed, representing 3.15% of all GNB tested. Seven isolates of New Delhi Metallo-β-lactamase (bla_NDM) were found among P. aeruginosa, K. pneumoniae, E. coli, and A. baumannii. The bla_NDM was identified in strains classified as extensively drug-resistant (XDR) and pandrug-resistant. Conversely, the bla_KPC was detected solely in multidrug-resistant and XDR strains. Conclusions: Emerging CR-GNB, specifically CP-GNB, in Nigeria emphasize the need for specific therapeutic management of infected patients. Antimicrobial stewardship and long-term surveillance efforts must be implemented in healthcare settings, as well as improved, accelerated microorganism identification techniques. Full article

The genus Corynebacterium is commonly isolated from camel uteri, yet it is rarely identified to the species level. During our routine clinical examination of she-camels brought to the hospital with history of reproductive and systemic health issues, four isolates from the uterus and one isolate from blood could not be assigned to any valid Corynebacterium species. Therefore, we aim to identify these isolates, determine any potential virulence factors, and describe how gene turnover contributed to the evolution of these species. Genome-based and phenotypic identification, along with resistome, mobilome, virulome and phylogenomics analysis, was used to characterize the isolates. The isolates were Gram stain-positive, catalase-positive, and rod-shaped. The isolates were assigned to the genus Corynebacterium based on 16S rRNA gene sequence similarity and phylogenetic analysis. The isolates 3274 and ayman were classified as two new Corynebacterium species based on the average nucleotide identity (ANI) values of 78.46% and 68.88% and digital DNA–DNA hybridization (dDDH) values of 20.9% and 22.4%. The isolates 2581A, 2583C, and 4168A constitute a single Corynebacterium species based on their pairwise ANI value of 99% and dDDH value of more than 90%. In addition, isolates 2581A, 2583C, and 4168A showed ANI values of 75.99%, 75.86%, and 76.04% and dDDH values of 23.1%, 23%, and 22.5% with closely related species, and were designated as single new Corynebacterium species. Genes for mycolic acid and menaquinone biosynthesis were detected in all isolates. The isolates were susceptible to ceftiofur, linezolid, penicillin, erythromycin, and tetracycline. All isolates harbored the antiseptic resistance gene qacA. Moreover, virulence factors involved in cell adhesion and iron acquisition were detected. The evolution of these species is dominated by gene gain rather than gene loss. The majority of these genes are acquired through horizontal gene transfer, mediated by prophages and genomic islands. In summary, we characterized three new Corynebacterium species, expanding the number of new Corynebacterium species from animals. Moreover, we described the mechanism underlying the genome evolution of these new species. The clinical findings and detection of virulence genes highlight the significance of these isolates as possible pathogens, contributing to the development of endometritis in camels. Full article

Introduction: Scrub typhus is caused by Gram-negative bacteria, Orientia tsutsugamushi. Humans are the dead-end host of scrub typhus. Currently, there is no vaccine available. The disease can be fatal without appropriate treatment. Here, we present the circulating OT genotypes in Malaysia and a tsa56-based single PCR to detect and determine OT genotypes, which is an approach to replace the time-consuming traditional nested PCR. Methods: The patients’ blood or tissue samples (n = 1200), received from all hospitals in Malaysia from December 2022 to November 2024, were screened for rickettsial infections. Both htrA qPCR and nested PCR were performed to detect the presence of OT DNA. Simultaneously, a selection of DNA was evaluated for the new single PCR protocol and confirmed with Sanger sequencing. Results: We report that Pahang state of Peninsular Malaysia presents the highest number of acute scrub typhus infections in Malaysia within the 24 months period. There are four genotypes circulating in the Malaysian population. OT genotype Gilliam (n = 31, 29.2%) and Karp (n = 31, 29.2%) are the predominant OT genotypes in Malaysia, followed by TA763 (n = 22, 20.8%) and Kato (n = 22, 20.8%). The single-run PCR presents longer sequence size and similar results with the nested PCR. Conclusions: Acute scrub typhus infection is not rare in Malaysia and should be considered for undifferentiated febrile illness. The single-run PCR protocol is time-saving and a promising approach for OT detection and genotype analysis in a single run to complement a clinical diagnostic setting and surveillance. Full article

The cellular envelope of Gram-negative bacteria is a space where processes that are extremely important for the proper functioning of bacteria and determining their virulence take place. The extracytoplasmic protein quality control system, which includes chaperones, protein-folding catalysts, and proteases, is responsible for maintaining homeostasis in this cellular compartment. This system has been well studied in the model bacterium Escherichia coli, but little is known about its function in other bacteria. In bacteria evolutionarily distant from Enterobacteriaceae, the protein quality control system appears to function differently. For example, in the phylum Campylobacterota, a number of homologs of folding factors and proteases, whose functions are important for maintaining homeostasis in the periplasm of E. coli, have not been identified. Instead, there are quality control components that have no similar counterparts in the Enterobacteriaceae. In this review, we present the current state of knowledge on the extracytoplasmic protein quality control system in the model Campylobacterota, C. jejuni and H. pylori. Full article

Due to their evolutionary divergence from mammals, zebrafish (Zf, Danio rerio), which are frequently employed in biomedical research, provide a distinctive viewpoint on innate immune systems. The Toll-like receptor 4/myeloid differentiation factor 2/cluster of differentiation 14 (TLR4/MD-2/CD14) complex in mammals detects lipopolysaccharide (LPS), a crucial component of Gram-negative bacteria, and it causes potent inflammatory reactions through a Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-β (TRIF)-dependent and myeloid differentiation primary response 88 (MyD88)-dependent pathways. However, key components of this system, such as a responsive TLR4 axis and a functional CD14 ortholog, are absent in Zf. The Zf species nevertheless reacts to LPS, which leads to research into other recognition systems. This review looks at a number of TLR4-independent processes in Zf, such as scavenger receptors (SRs) including scavenger receptor class B type 1 (SR-BI) and cluster of differentiation 36 (CD36), nucleotide-binding oligomerization domain-containing protein 1 (NOD1)-dependent cytosolic sensing, peptidoglycan recognition proteins (PGRPs), Complement Component 3 (C3), and caspase-1-like protein 2 (Caspy2)-mediated inflammasome activation. An alternative and flexible immune system that makes up for the lack of canonical TLR4 signaling is revealed by these mechanisms. Additionally, the discovery of lymphocyte antigen 96 (ly96), an ortholog of MD-2 found in Zf, suggests evolutionary similarity; however, as it is only functional in artificial systems, it demonstrates minimal overlap with mammalian MD-2 activity. Knowing these pathways provides important information for studying inflammation, infection, and immunological modulation in vertebrates using Zf as a model. It also clarifies the evolutionary flexibility of innate immune recognition. Full article

Background/Objectives. Multi-drug-resistant (MDR) microorganisms pose a significant challenge in healthcare settings, particularly with beta-lactam-resistant Gram-negative bacteria and glycopeptide-resistant enterococci. Culture represents the most reliable technique in determining their presence within surveillance swabs. However, it requires a long time-to-result (TTR) and shows low sensitivity. Molecular techniques integrate diagnostic procedures, allowing TTR reduction and precise identification of genes. Methods. During our usual surveillance campaign, we had the opportunity to evaluate the Allplex Entero-DR assay (Seegene Inc., Seoul, Republic of Korea) and the Entero-DR Plus assay (Arrow Diagnostics srl, Genova, Italy) molecular kits for the detection of extended-β-lactamases (ESBL), carbapenem- and vancomycin-resistant genes, as well as Acinetobacter spp. and Pseudomonas aeruginosa spp. identification directly from rectal swabs. A comparison between these tests and the culture-based routine completed the study. Results. The analysis included 300 rectal swabs from the University Hospital Policlinico (Catania, Italy). One hundred and eighty-eight samples (62.6%) resulted as positive for at least one Allplex™ target, reaching optimal sensitivity and negative predictive value (100%). Our results underlined the ubiquitous blaCTX-M and van genes presence and demonstrated the diffusion of double-carbapenemases genes and metallo-β-lactamases-producing strains. In our epidemiological setting, few data were collected about carbapenem-resistant P. aeruginosa and Acinetobacter spp., which require further evaluations on simultaneous respiratory colonization and higher sample numbers. Conclusions. Our analysis highlighted the importance of combining conventional and advanced diagnostic methods in investigating MDR pathogens. The right approach should be based on the prevalence and variability of resistance mechanisms within a specific epidemiological area. Remarkably, molecular screenings may exclude negative samples within high-risk areas due to a significant negative predictive value. Full article