Gram-negative Bacterial Pathogens Research Articles

A multicentric survey and single-centre observational study of usage behaviour of sinks in intensive care: training is needed to minimize risk

Abstract Introduction Sinks have been introduced near patients to improve hand hygiene as part of infection prevention and control measures. However, sinks are a known reservoir for gram-negative bacterial pathogens in particular and their removal to prevent bacterial infections in intensive care patients is currently recommended by several international guidelines. Methods Healthcare workers (HCWs) in 15 intensive care units (ICUs) in Germany were given the opportunity to complete an anonymous survey on the use of sinks between August 2022 and January 2023. Observations were then made in three participating ICUs to determine the frequency and reason for contact with the sink. Results 258 questionnaires were returned (nurses 87%). 90% found it useful to very useful to have a sink in the patient room, and 56% reported using it daily for hand hygiene. We observed 33 contacts between nurses and sinks over 17 h. In 20/33 (60%) cases, the sink was used for waste disposal. In 3/33 (10%) it was used for hand washing. Discussion Sinks are still used for daily care in intensive care units. Educational Interventions in existing buildings to minimise risk through “sink hygiene” (i.e. separation of sinks for water disposal and uptake) can make an important contribution to infection prevention.

Transcriptomic profiling of 'Candidatus Liberibacter asiaticus' in different citrus tissues reveals novel insights into Huanglongbing pathogenesis.

'Candidatus Liberibacter asiaticus' (Las) is a gram-negative bacterial pathogen associated with citrus huanglongbing (HLB) or greening disease. Las is transmitted by the Asian citrus psyllid (ACP) where it colonizes the phloem tissue, resulting in substantial economic losses to citrus industry worldwide. Despite extensive efforts, effective management strategies against HLB remain elusive, necessitating a deeper understanding of the pathogen's biology. Las undergoes cell-to-cell movement through phloem flow and colonizes different tissues in which Las may have varying interactions with the host. Here, we investigate the transcriptomic landscape of Las in citrus seed coat vasculatures, enabling a complete gene expression profiling of Las genome and revealing unique transcriptomic patterns compared to previous studies using midrib tissues. Comparative transcriptomics between seed coat, midrib and ACP identified specific responses and metabolic states of Las in different host tissue. Two Las virulence factors that exhibit higher expression in seed coat can suppress callose deposition. Therefore, they may contribute to unclogging sieve plate pores during Las colonization in seed coat vasculature. Furthermore, analysis of regulatory elements uncovers a potential role of LuxR-type transcription factors in regulating Liberibacter effector gene expression during plant colonization. Together, this work provides novel insights into the pathogenesis of the devastating citrus HLB.

Longitudinal genomic surveillance of a UK intensive care unit shows a lack of patient colonisation by multi-drug-resistant Gram-negative bacterial pathogens.

Vulnerable patients in an intensive care unit (ICU) setting are at high risk of infection from bacteria including gut-colonising Escherichia coli and Klebsiella species. Complex ICU procedures often depend on successful antimicrobial treatment, underscoring the importance of understanding the extent of patient colonisation by multi-drug-resistant organisms (MDROs) in large UK ICUs. Previous work on ICUs globally uncovered high rates of colonisation by transmission of MDROs, but the situation in UK ICUs is less understood. Here, we investigated the diversity and antibiotic resistance gene (ARG) carriage of bacteria present in one of the largest UK ICUs at the Queen Elizabeth Hospital Birmingham (QEHB), focusing primarily on E. coli as both a widespread commensal and a globally disseminated multi-drug-resistant pathogen. Samples were taken during highly restrictive coronavirus disease 2019 (COVID-19) control measures from May to December 2021. Whole-genome and metagenomic sequencing were used to detect and report strain-level colonisation of patients, focusing on E. coli sequence types (STs), their colonisation dynamics and antimicrobial resistance gene carriage. We found a lack of multi-drug resistance (MDR) in the QEHB. Only one carbapenemase-producing organism was isolated, a Citrobacter carrying bla KPC-2. There was no evidence supporting the spread of this strain, and there was little evidence overall of nosocomial acquisition or circulation of colonising E. coli. Whilst 22 different E. coli STs were identified, only 1 strain of the pandemic ST131 lineage was isolated. This ST131 strain was non-MDR and was found to be a clade A strain, associated with low levels of antibiotic resistance. Overall, the QEHB ICU had very low levels of pandemic or MDR strains, a result that may be influenced in part by the strict COVID-19 control measures in place at the time. Employing some of these infection prevention and control measures where reasonable in all ICUs might therefore assist in maintaining low levels of nosocomial MDR.

Efflux-mediated Multidrug Resistance in Critical Gram-negative Bacteria and Natural Efflux Pump Inhibitors.

Multidrug Resistance mechanisms in microorganisms confer the slackness of the existing drugs, leading to added difficulty in treating infections. As a consequence, efficient novel drugs and innovative therapies to treat MDR infections are necessarily required. One of the primary contributors to the emergence of multidrug resistance in gram-negative bacteria has been identified as the efflux pumps. These transporter efflux pumps reduce the intracellular concentration of antibiotics and aid bacterial survival in suboptimal low antibiotic concentration environments that may cause treatment failure. The reversal of this resistance via inhibition of the efflux mechanism is a promising method for increasing the effectiveness of antibiotics against multidrug-resistant pathogens. Such EPI, in combination with antibiotics, can make it easier to reintroduce traditional antibiotics into clinical practice. This review mostly examines efflux-mediated multidrug resistance in critical gram-negative bacterial pathogens and EPI of plant origin that have been reported over previous decades.

Overexpression of l,d-Transpeptidase A Induces Dispensability of Rod Complex in Escherichia coli.

Antimicrobial resistance (AMR) is a significant global threat, and the presence of resistance-determinant genes is one of the major driving forces behind it. The bacterial rod complex is an essential set of proteins that is crucial for cell survival due to its role in cell wall biogenesis and shape maintenance. Therefore, these proteins offer excellent potential as drug targets; however, compensatory mutations in nontarget genes render this complex nonessential. The MreB protein of this complex is an actin homologue that rotates along the longitudinal axis of the cell to provide rod shape to the bacteria. In this study, using chemical-chemical interaction profiling and FtsZ suppression assay, we identified the MreB targeting activity of IITR07865, a previously discovered small molecule in our lab. Escherichia coli suppressors against IITR07865 revealed mutations in two cell division-associated genes, min C and pal, that have not been previously implicated in rod complex essentiality. IITR07865 resistant mutants were found to inactivate and render the rod complex nonessential, making the rod complex inhibitors ineffective. Further, through transcriptome analysis, we reveal the primary cause of resistance in suppressor strains to be the overexpression of an l, d-transpeptidase A enzyme, which is involved in peptidoglycan and Braun's lipoprotein cross-linking. Our results demonstrate a novel mechanism of resistance development in rod-shaped Gram-negative bacterial pathogen E. coli involved in UTIs where mecillinam, a clinically used antibiotic that targets rod complex, is a drug of choice.

Uncovering Candidate Pathogenicity Genes in Erwinia pyrifoliae YKB12327 via Tn5-insertion Mutagenesis

<i>Erwinia pyrifoliae</i> is a gram-negative bacterial pathogen that commonly causes black shoot blight in pear and apple tree. Although the pathogenicity of this bacterial species is very similar to <i>E. amylovora</i>, there is no specific explanation of its pathogenic genes and mechanisms. In this study, our investigation into <i>E. pyrifoliae</i> pathogenicity involved generating seven YKB12327 mutant strains using Tn5 transposon mutagenesis. Observations revealed weakened growth rate and loss of pathogenicity in these mutants. Whole-genome sequencing and alignment analysis identified transposon insertions within the coding sequences of five strains and in the intergenic region of two strains. Annotation analysis elucidated genes directly or indirectly associated with pathogenicity. Notably, mutant strain MT16 displayed a transposon insertion mutation in the cyclic-di-GMP phosphodiesterase (<i>pdeF</i>) gene, a key player in bacterial signaling, governing microbial behavior and adaptation to environmental changes. Our findings provide insights into the genetic regulation of <i>E. pyrifoliae</i> pathogenicity, suggesting potential avenues for further research aimed at understanding and controlling this bacterial pathogen by targeting <i>pdeF</i> to mitigate apple black shoot blight disease.

Adsorptive potential of dispersible chitosan-coated biogenic iron oxide nanocomposite for enhanced anti-bacterial activity against gram-positive and gram-negative bacterial pathogens

The use of various biomaterials, such as plants or microbes, to create nanoparticles (NPs), is seen as a viable strategy in green nanotechnology. The synthesis of low-cost, energy-efficient, nontoxic, ecologically acceptable metallic nanoparticles has recently become a critical topic. The biosynthesis of iron oxide NPs using pomegranate peel extract has been investigated. Biogenic iron oxide NPs were coated with highly porous chitosan as a supporting material to enhance applicability of NPs for wastewater remediation. Biogenic magnetic NPs and its composite were characterized by scanning electron microscope, X-ray diffraction, and Fourier Transformer Infrared spectroscopy (FTIR). Our study focused on the ability of biogenic magnetite Fe3O4 NPs and its bio-composite for removal of As+5 ions from wastewater. Adsorption isotherms were obtained using metal ion concentrations ranging from 5 to 25 mg/L. The Langmuir adsorption model was validated by our data. The reaction kinetics of the adsorption process were pseudo-second order. Interestingly, the bio-composite achieved 90% As+5 removal at pH4. In addition, the prepared nanocomposite was characterized using various analytical techniques to confirm its physicochemical properties. The adsorptive capacity of the nanocomposite was evaluated by studying the removal of pollutants and contaminants from aqueous solutions. Additionally, the antibacterial activity of the nanocomposite was assessed against a panel of clinically relevant Gram-positive and Gram-negative bacterial strains, including Staphylococcus epidermidis (RCMB 9241, ATCC 12228), Staphylococcus saprophyticus (RCMB 010028, ATCC 15305), Enterococcus faecalis (RCMB 010052), Streptococcus salivarius (ATCC 13415), Escherichia coli (RCMB 010052, ATCC 25922), Salmonella enterica serovar Typhimurium (RCMB 006(1), ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853). Our findings have important implications in the field of low-cost, easy, and environmentally friendly water bioremediation.

EspH utilizes phosphoinositide and Rab binding domains to interact with plasma membrane infection sites and Rab GTPases*

ABSTRACT Enteropathogenic E. coli (EPEC) is a Gram-negative bacterial pathogen that causes persistent diarrhea. Upon attachment to the apical plasma membrane of the intestinal epithelium, the pathogen translocates virulence proteins called effectors into the infected cells. These effectors hijack numerous host processes for the pathogen’s benefit. Therefore, studying the mechanisms underlying their action is crucial for a better understanding of the disease. We show that translocated EspH interacts with multiple host Rab GTPases. AlphaFold predictions and site-directed mutagenesis identified glutamic acid and lysine at positions 37 and 41 as Rab interacting residues in EspH. Mutating these sites abolished the ability of EspH to inhibit Akt and mTORC1 signaling, lysosomal exocytosis, and bacterial invasion. Knocking out the endogenous Rab8a gene expression highlighted the involvement of Rab8a in Akt/mTORC1 signaling and lysosomal exocytosis. A phosphoinositide binding domain with a critical tyrosine was identified in EspH. Mutating the tyrosine abolished the localization of EspH at infection sites and its capacity to interact with the Rabs. Our data suggest novel EspH-dependent mechanisms that elicit immune signaling and membrane trafficking during EPEC infection.

Phytosynthesis of titanium dioxide nanoparticles using Cynodon dactylon leaf extract and their antibacterial activity

Due to use of nanoparticles, nanotechnology has become an important area of research penetrating in all the fields of science and technology including medicinal chemistry. Titanium dioxide nanoparticles (TiO2 NPs) play an important role in biotechnology and nanomedicine because of their antimicrobial effect against many pathogens such as bacteria, fungus, viruses and yeast. In this article, we propose an eco-friendly phytosynthesis method of TiO2 NPs using aqueous leaf extract of Cynodon dactylon herbal plant as a reducing agent. The formation of TiO2 NPs by plant bio-molecules involved in the reduction of metal ions to nanoparticles is demonstrated. The synthesized TiO2 NPs are analyzed using X-ray diffraction analysis, Fourier transform infrared spectroscopy, laser Raman spectroscopy and field emission scanning electron microscopy. The antibacterial activity of the TiO2 NPs against gram-positive bacterial pathogens like Bacillus subtilis and Staphylococcus aureus as well as gram-negative bacterial pathogen like Escherchia coli is tested. The obtained results demonstrate potent bactericidal activity of the TiO2 NPs.

TolC and EmrA1 contribute to Francisella novicida multidrug resistance and modulation of host cell death.

Francisella tularensis is a Gram-negative intracellular bacterial pathogen and causative agent of tularemia. We previously identified the outer membrane channel protein TolC as contributing to antimicrobial resistance and subversion of host responses by F. tularensis. To advance understanding of TolC function in Francisella and to identify components that might work together with TolC, we took advantage of a transposon mutant library in F. novicida, a model species that causes a tularemia-like disease in mice. Our findings identify TolC and the membrane fusion protein EmrA1 as important for both antimicrobial resistance and suppression of macrophage cell death. This study also revealed differences in cell death pathways triggered by F. novicida versus F. tularensis infection that may relate to differences in virulence.

Antimicrobial resistance profile and associated factors of hospital-acquired gram-negative bacterial pathogens among hospitalized patients in northeast Ethiopia

BackgroundAntimicrobial resistance is a major global public health issue. Infections caused by resistant species are associated with higher mortality rates, longer hospital stays, medication failure, and rising medical costs. The World Health Organisation has declared multidrug resistance-associated infections as an epidemic of public health concern.ObjectiveThis study aimed to evaluate the antimicrobial resistance profile and associated factors of hospital-acquired Gram-negative bacterial pathogens among hospitalized patients in Northeast Ethiopia.Materials and methodsA health facility-based cross-sectional study was conducted among hospitalized patients from March 2021 to February 2022. About 810 clinical specimens were collected, transported, and processed from admitted patients following the standard bacteriological procedures. The clinical samples were inoculated onto blood agar, MacConkey agar, and chocolate agar. Furthermore, the species identification was done using gram reactions, colony morphology, and color and biochemical tests. Antimicrobial susceptibility tests, extended-spectrum beta-lactamase, and carbapenemase production were performed as per the clinical laboratory standard institute guidelines. For analysis, the information was entered into Epi-data and exported to SPSS. A P value of < 0.05 with a 95% confidence interval was considered as a statistically significant association.ResultsOut of 810 clinical specimens, 285/810 (35.2%) developed bacterial infections. From the isolated bacteria, E. coli was the predominant bacteria accounting for 78/285 (27.4%) followed by K. pneumoniae, 69/285(24.42%), whereas P. vulgaris accounted for the least, 7/285 (2.5%). Overall, 132/285 (46.3%) and 99/285 (34.7%) of culture-positive patients were infected by extended-spectrum beta-lactamase and carbapenemase-producing bacteria. The overall multidrug resistance rate of the isolated bacteria was 89.4%. The highest antibiotic resistance rates were detected for doxycycline (92.9%), amoxicillin-clavulanic acid (83.9%), and ampicillin (93%). The least antibiotic resistance rate was observed for meropenem at 41.1% and amikacin at 1.7%, respectively.Conclusions and recommendationsIn the study area, significant health concerns include a range of hospital-acquired bacterial infections associated with elevated rates of multidrug resistance, Extended-spectrum beta-lactamase (ESBL), and carbapenemase-producing bacterial pathogens. Consequently, it is recommended to conduct drug-susceptibility testing of isolates and molecular detection at a national level to optimize antibiotic usage for treating prevalent bacterial infections in this area.

Extended-spectrum β-lactamase-producing Escherichia coli from poultry: A review.

Extended-spectrum β-lactamases (ESBLs) are β-lactamase enzymes produced by Gram-negative bacterial pathogens that harbor the ESBL genes. In addition, most ESBL genes are plasmid-mediated and usually encode a broader spectrum of antimicrobial resistance, especially to penicillins, first-generation, second-generation, and third-generation cephalosporins, as well as monobactam, such as aztreonam. Escherichia coli has become an opportunistic pathogen, especially in poultry, and has been implicated in zoonotic diseases that can be transmitted to humans, resulting in public health problems. Poultry can act as carriers of ESBL-producing E. coli (ESBL-EC) bacteria to humans through poultry meat that is contaminated by waste products, feces, and excretions. The ESBL gene CTX-M type was identified as the main cause of infection in humans and was detected in poultry as a cause of infection accompanied by clinical symptoms. Several studies have also shown a link between E. coli and ESBL gene transfer from birds to humans. Controlling the spread of ESBL-EC involves maintaining the cleanliness of poultry products, especially meat, and eliminating contaminant sources from poultry. Likewise, maintaining the environmental cleanliness of poultry slaughterhouses and poultry farms must be taken as a precautionary measure to curtail the increasing spread of ESBL-EC into the environment. This review aimed to explain the spread of ESBL-producing E. coli in poultry.

Characterizing Secretion System Effector Proteins With Structure-Aware Graph Neural Networks and Pre-Trained Language Models.

The Type III Secretion Systems (T3SSs) play a pivotal role in host-pathogen interactions by mediating the secretion of type III secretion system effectors (T3SEs) into host cells. These T3SEs mimic host cell protein functions, influencing interactions between Gram-negative bacterial pathogens and their hosts. Identifying T3SEs is essential in biomedical research for comprehending bacterial pathogenesis and its implications on human cells. This study presents EDIFIER, a novel multi-channel model designed for accurate T3SE prediction. It incorporates a graph structural channel, utilizing graph convolutional networks (GCN) to capture protein 3D structural features and a sequence channel based on the ProteinBERT pre-trained model to extract the sequence context features of T3SEs. Rigorous benchmarking tests, including ablation studies and comparative analysis, validate that EDIFIER outperforms current state-of-the-art tools in T3SE prediction. To enhance EDIFIER's accessibility to the broader scientific community, we developed a webserver that is publicly accessible at http://edifier.unimelb-biotools.cloud.edu.au/. We anticipate EDIFIER will contribute to the field by providing reliable T3SE predictions, thereby advancing our understanding of host-pathogen dynamics.

VirB11, a traffic ATPase, mediated flagella assembly and type IV pilus morphogenesis to control the motility and virulence of Xanthomonas albilineans.

Xanthomonas albilineans (Xal) is a gram-negative bacterial pathogen responsible for developing sugarcane leaf scald disease, which engenders significant economic losses within the sugarcane industry. In the current study, homologous recombination exchange was carried out to induce mutations within the virB/D4-like type IV secretion system (T4SS) genes of Xal. The results revealed that the virB11-deletion mutant (ΔvirB11) exhibited a loss in swimming and twitching motility. Application of transmission electron microscopy analysis further demonstrated that the ΔvirB11 failed to develop flagella formation and type IV pilus morphology and exhibited reduced swarming behaviour and virulence. However, these alterations had no discernible impact on bacterial growth. Comparative transcriptome analysis between the wild-type Xal JG43 and the deletion-mutant ΔvirB11 revealed 123 differentially expressed genes (DEGs), of which 28 and 10 DEGs were notably associated with flagellar assembly and chemotaxis, respectively. In light of these findings, we postulate that virB11 plays an indispensable role in regulating the processes related to motility and chemotaxis in Xal.

Blockade of IKK signaling induces RIPK1-independent apoptosis in human macrophages.

Regulated cell death in response to microbial infection plays an important role in immune defense and is triggered by pathogen disruption of essential cellular pathways. Gram-negative bacterial pathogens in the Yersinia genus disrupt NF-κB signaling via translocated effectors injected by a type III secretion system, thereby preventing induction of cytokine production and antimicrobial defense. In murine models of infection, Yersinia blockade of NF-κB signaling triggers cell-extrinsic apoptosis through Receptor Interacting Serine-Threonine Protein Kinase 1 (RIPK1) and caspase-8, which is required for bacterial clearance and host survival. Unexpectedly, we find that human macrophages undergo apoptosis independently of RIPK1 in response to Yersinia or chemical blockade of IKKβ. Instead, IKK blockade led to decreased cFLIP expression, and overexpression of cFLIP contributed to protection from IKK blockade-induced apoptosis in human macrophages. We found that IKK blockade also induces RIPK1 kinase activity-independent apoptosis in human T cells and human pancreatic cells. Altogether, our data indicate that, in contrast to murine cells, blockade of IKK activity in human cells triggers a distinct apoptosis pathway that is independent of RIPK1 kinase activity. These findings have implications for the contribution of RIPK1 to cell death in human cells and the efficacy of RIPK1 inhibition in human diseases.

Fitness factor genes conserved within the multi-species core genome of Gram-negative Enterobacterales species contribute to bacteremia pathogenesis.

There is a critical gap in knowledge about how Gram-negative bacterial pathogens, using survival strategies developed for other niches, cause lethal bacteremia. Facultative anaerobic species of the Enterobacterales order are the most common cause of Gram-negative bacteremia, including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, and Enterobacter hormaechei. Bacteremia often leads to sepsis, a life-threatening organ dysfunction resulting from unregulated immune responses to infection. Despite a lack of specialization for this host environment, Gram-negative pathogens cause nearly half of bacteremia cases annually. Based on our existing Tn-Seq fitness factor data from a murine model of bacteremia combined with comparative genomics of the five Enterobacterales species above, we prioritized 18 conserved fitness genes or operons for further characterization. Mutants were constructed for all genes in all five species. Each mutant was used to cochallenge C57BL/6 mice via tail vein injection along with each respective wild-type strain to determine competitive indices for each fitness gene. Five fitness factor genes, when mutated, attenuated mutants in four or five species in the spleen and liver (tatC, ruvA, gmhB, wzxE, arcA). Five additional fitness factor genes or operons were validated as outcompeted by wild-type in three, four, or five bacterial species in the spleen (xerC, prc, apaGH, atpG, aroC). Overall, 17 of 18 fitness factor mutants were attenuated in at least one species in the spleen or liver. Together, these findings allow for the development of a model of bacteremia pathogenesis that may include future targets of therapy against bloodstream infections.

Repurposing cetylpyridinium chloride and domiphen bromide as phosphoethanolamine transferase inhibitor to combat colistin-resistant Enterobacterales

The emergence of plasmid-encoded colistin resistance mechanisms, MCR-1, a phosphoethanolamine transferase, rendered colistin ineffective as last resort antibiotic against severe infections caused by clinical Gram-negative bacterial pathogens. Through screening FDA-approved drug library, we identified two structurally similar compounds, namely cetylpyridinium chloride (CET) and domiphen bromide (DOM), which potentiated colistin activity in both colistin-resistant and susceptible Enterobacterales. These compounds were found to insert their long carbon chain to a hydrophobic pocket of bacterial phosphoethanolamine transferases including MCR-1, competitively blocking the binding of lipid A tail for substrate recognition and modification, resulting in the increase of bacterial sensitivity to colistin. In addition, these compounds were also found to dissipate bacterial membrane potential leading to the increase of bacterial sensitivity to colistin. Importantly, combinational use of DOM with colistin exhibited remarkable protection of test animals against infections by colistin-resistant bacteria in both mouse thigh infection and sepsis models. For mice infected by colistin-susceptible bacteria, the combinational use of DOM and colistin enable us to use lower dose of colistin to for efficient treatment. These properties render DOM excellent adjuvant candidates that help transform colistin into a highly potent antimicrobial agent for treatment of colistin-resistant Gram-negative bacterial infections and allowed us to use of a much lower dosage of colistin to reduce its toxicity against colistin-susceptible bacterial infection such as carbapenem-resistant Enterobacterales.

Discovery of D8-03 as an Inhibitor of Intracellular Growth of Francisella tularensis.

Francisella tularensis is a Gram-negative facultative intracellular bacterial pathogen that is classified by the Centers for Disease Control and Prevention as a Tier 1 Select Agent. F. tularensis infection causes the disease tularemia, also known as rabbit fever. Treatment of tularemia is limited to few effective antibiotics which are associated with high relapse rates, toxicity, and potential emergence of antibiotic-resistant strains. Consequently, new therapeutic options for tularemia are needed. Through screening a focused chemical library and subsequent structure-activity relationship studies, we have discovered a new and potent inhibitor of intracellular growth of Francisella tularensis, D8-03. Importantly, D8-03 effectively reduces bacterial burden in mice infected with F. tularensis. Preliminary mechanistic investigations suggest that D8-03 works through a potentially novel host-dependent mechanism and serves as a promising lead compound for further development.

Broad-Spectrum Antibacterial Activity of Antioxidant Octyl Gallate and Its Impact on Gut Microbiome.

In this study, we investigated the antibacterial activity of octyl gallate (OG), an antioxidant food additive, against both Gram-positive and Gram-negative bacterial pathogens. OG demonstrated robust bactericidal activity against Gram-positive bacterial pathogens with minimum inhibitory concentrations (MIC) of 4 to 8 µg/mL and minimum bactericidal concentrations (MBC) of 8 to 16 µg/mL in vitro. However, OG exhibited limited antibacterial activity against Gram-negative bacteria, including E. coli, although it could inhibit bacterial growth in vitro. Importantly, OG administration in mice altered the fecal microbiome, significantly reducing microbial diversity, modifying community structure, and increasing the abundance of beneficial bacteria. Additionally, OG displayed low cytotoxicity and hemolytic activity. These findings suggest that OG could be developed as a novel antibacterial agent, particularly against multi-drug-resistant MRSA. Our results provide new insights into the therapeutic potential of OG in modulating the gut microbiome, especially in conditions associated with microbial imbalance, while ensuring food safety.

Magnitude and antimicrobial susceptibility profile of bacteria isolated from pediatric sepsis cases at University of Gondar Hospital, Northwest Ethiopia

BackgroundSepsis is one of the major causes of morbidity and mortality among pediatric patients throughout the world. The varying microbiological pattern of sepsis warrants the need for researches on the causative organisms and their antimicrobial susceptibility pattern. The epidemiology of neonatal and pediatric sepsis in Ethiopia is under-research. The objective of this study was to evaluate the burden of bacterial pathogens and their antimicrobial susceptibility patterns among children suspected of sepsis.MethodsAn institutional-based prospective cross-sectional study was conducted on 370 pediatric(age birth-15 years) patients suspected of sepsis at the University of Gondar Comprehensive Specialized hospital from December 2020 to November 2021. Blood samples were collected aseptically and inoculated into Tryptone Soya Broth for culture. The organisms grown were identified by standard microbiological methods and subjected to antibiotic susceptibility testing by modified Kirby-Bauer disk diffusion method recommended by Clinical laboratory and standard institute. Methicillin resistance was confirmed using Cefoxitin disk diffusion method. Data entry and analysis were done using Statistical Package for Social Sciences (SPSS) version 26 software. A p-value less than 0.05 at 95% confidence interval was considered statically significant.ResultsOut of the total 370 study subjects, 21.6% (80/370) of them were culture positive. Of these, 43 (53.8%) and 37 (46.3%) were Gram-positive and Gram-negative bacterial pathogens, respectively. The most prevalent Gram-positive bacterial isolate was Staphylococcus aureus (n = 24; 30%) and coagulase negative staphylococci (n = 7; 8.8%). Among the Gram-negative bacterial isolates, the leading bacteria was Klebsiella pneumoniae (n = 20; 25%) followed by Escherichia coli (n = 7; 8.8%). Clindamycin, Chloramphenicol, Gentamicin and Ciprofloxacin were the most effective antibiotics against Gram-positive bacterial isolates while Amikacin, Meropenem and Chloramphenicol were effective against Gram-negative pathogens. Methicillin resistance was detected in 45.8% of Staphylococcus aureus. Multi-drug resistance (MDR) antimicrobial susceptibility pattern was observed in 76% of the bacterial isolates.ConclusionGram positive bacteria were the predominant isolates among pediatric sepsis cases and most of the bacterial isolates showed MDR. Staphylococcus aureus and Klebsiella pneumoniae were frequently isolated bacteria. The high prevalence of drug resistance warrants rational use of antibiotics and the need for regular antibiotic susceptibility surveillance studies.