Gram-negative Enteric Bacteria Research Articles

The effect of epetraborole on the transcriptome and proteome profiles of an Escherichia coli strain overexpressing leuS, Leucyl-tRNA Synthetase

Epetraborole (EP) is a boron-containing antibiotic known for its effectiveness against gram-negative enteric bacteria and Mycobacterium species. It is designed to bind and inhibit the LeuS enzyme (Leucyl-tRNA Synthetase), which is encoded by the essential gene leuS in Escherichia coli. EP inhibits protein translation, impeding bacterial growth. However, when leuS is overexpressed in a recombinant plasmid, the amount of EP required for growth inhibition needs to be increased. This study explored the impact of EP on the transcriptome and proteome of E. coli overexpressing leuS, aiming to reveal additional gene and pathway insights beyond LeuS, shedding light on the biochemical players orchestrating the bacterium’s molecular response. 2D-PAGE Proteomics analysis identified four differentially regulated proteins influenced by EP in the leuS overexpression strain. Notably, LeuA and DeoA emerged as identified proteins. EP may affect LeuA in the cells overexpressing LeuS, which could result in truncated LeuA protein variants. Transcriptomics analyses, based on microarray data, revealed 23 up-regulated and 9 down-regulated genes responding to EP in the overexpression strain (p2). Based on the statistical analyses, the first five up-and down-regulated genes showing the highest fold differences in their mRNA levels are yiaW, mglB, narH, ybiO, flgB and yhdY, deoR, recX, yobB, potF, respectively. Analyses using the Omics Dashboard pathway and String indicate that the EP effect on the leuS overexpressing strain mainly induces alterations in the expression of genes related to the cell exterior, regulation, and response to stimuli. It is suggested that EP and higher levels of LeuS may interfere with the translational and transcriptional regulation of the expression of the leuA gene, which encodes the first enzyme, 2-isopropylmalate synthase, in L-leucine biosynthesis. This study offers new insights into the effects of EP on the bacterium, specifically when the level of the aminoacyl-tRNA synthetase LeuS is increased.

Degradation and molecular docking of Curli to scout aggregation complexion

Curli, an extracellular protein fibril produced by certain gram-negative enteric bacteria, is responsible for neuro-degenerative diseases due to spontaneous misfolding of soluble proteins. This study investigates the effect of denaturing agents (Urea, Guanidine Hydrochloride) and varying pH (2–11) on the conformation of Curli protein, isolated from E. coli PHL628, due to changes in the external environment. The study focuses on the changing dynamics of the protein using intrinsic fluorescence property, UV-absorption, fluorescence anisotropic measurements, and extrinsic fluorescence property with the help of interaction with 1-anilinonaphthalene-8-sulphonate (ANS). The data showed that the absorption maximum (λmax) of protein was altered in variation of denaturant concentration and buffer pH. Molecular docking results revealed the interaction of Curli with Urea and GdnHCl, by comparing structural changes. This study determines how denaturants and changes in the external environment cause denaturation or modification in the folded structure of Curli protein and provides insight into binding sites of Curli with denaturants.

Isolation and Identification of Bacterial Contamination Water Supply in Shendi City-Sudan

Background: Microbial contamination of water persists to be a significant problem; the usual source is human and animal fecal matter that has contaminated the water systems. The presence of bacteria and pathogenic organisms is of great concern when considering the safety of drinking water, as pathogenic organisms can cause watery diarrhea, cholera, typhoid fever, and other illnesses. Objective: This is a prospective tap water examination study to find groundwater microbiological fecal contamination. Materials and Methods: Water samples for laboratory examination were collected from a different area of Shendi city, which were classified as Tap water. Each sample was a collection in a sterile container and then isolated and Confirmation by biochemical test. Results: Tap water samples were found to be contaminated with E. coli about 80 (63.6%) samples, an indicator of contamination with the fecal matter of animals and humans. It was the isolation of other Gram-negative enteric bacteria such as Salmonella and pseudomonas these were not scientific indicators of water contamination by animal and human fecal matter. Conclusions: Tap Water was contaminated with feces and posed a health risk to consumers of that water and was found to be contaminated with E.coli bacteria. Future studies are needed to understand the complicated issues concerning water quality in the city. Community-led sanitation and hygiene education and better water source protection are urgently required.

Influence of probiotic and prebiotic supplementation on intestinal microbiota and resistance to Edwardsiella ictaluri infection in channel catfish (Ictalurus punctatus) following florfenicol administration.

Enteric septicemia of catfish (ESC), caused by the gram-negative enteric bacteria Edwardsiella ictaluri, is a significant threat to catfish aquaculture in the southeastern United States. Antibiotic intervention can reduce mortality; however, antibiotic use results in an imbalance, or dysbiosis, of the gut microbiota, which may increase susceptibility of otherwise healthy fish to enteric infections. Herein, recovery of the intestinal microbiota and survivability of channel catfish in response to ESC challenge was evaluated following a 10-day course of florfenicol and subsequent probiotic or prebiotic supplementation. Following completion of florfenicol therapy, fish were transitioned to a basal diet or diets supplemented with a probiotic or prebiotic for the remainder of the study. Digesta was collected on Days 0, 4, 8 and 12, beginning on the first day after cessation of antibiotic treatment, and gut microbiota was characterized by Illumina sequencing of the 16S rRNA gene (V4 region). Remaining fish were challenged with E. ictaluri and monitored for 32 days post-challenge. Florfenicol administration resulted in dysbiosis characterized by inflated microbial diversity, which began to recover in terms of diversity and composition 4 days after cessation of florfenicol administration. Fish fed the probiotic diet had higher survival in response to ESC challenge than the prebiotic (p = .019) and negative control (p = .029) groups.

2836. Prostate Abscess due to Staphylococcus aureus: a Retrospective Case Series

Abstract Background Most cases of prostate abscess are due to gram-negative enteric bacteria, but there are increasing reports of Staphylococcus aureus as a causative pathogen. Due to being an uncommon diagnosis, there are no current guidelines for the evaluation and treatment of S. aureus prostate abscesses. We examined the epidemiology and management of prostatic abscess due to S. aureus at an academic, urban tertiary center. Methods In this retrospective analysis, we identified patients with diagnosis of prostate abscess and concomitant culture with S. aureus who were aged 18 years or older and hospitalized at Temple University Hospital between 2016 and 2022. Cases were identified if they had both (1) a diagnosis code consistent with prostate abscess; and (2) positive blood, urine, or abscess cultures with S. aureus. Each case was reviewed to verify clinical or imaging criteria for diagnosis. Data regarding risk factors, interventions, and outcomes were compiled in REDCap, a de-identified electronic database for data management. Results We identified 18 patients who met inclusion criteria, with median [IQR] age of 50 years [40-70]. Computed tomography was used in all cases for identifying an abscess. The most common risk factors were intravenous drug use (IVDU) 55.6% [10/18] and diabetes 50% [9/18]. Culture positivity was 100% [6/6] for abscess fluid, 61.1% [11/18] for urine, and 56.3% [9/16] for blood. Of these, methicillin resistance was detected in 72.2% [13/18] of cases. Computed tomography was used in all cases for identifying an abscess. 61.1% [11/18] of patients underwent procedural interventions for treatment. Infectious Diseases consultation resulted in a change in management in 92.8% [13/14] of cases, with a median length of antibiotic administration of 42 days. 66.7% [6/9] of the bacteremic patients had additional infectious complications such as endocarditis or osteomyelitis. Conclusion Prostate abscess due to S. aureus should be considered in patients presenting with lower urinary tract symptoms and a history of injection drug use or diabetes. Evaluation should include imaging and cultures, particularly from blood. Treatment involves prolonged antibiotics and urology consultation for consideration of procedural intervention. Disclosures All Authors: No reported disclosures

Effects of Dietary Supplementation of Peppermint Extract on Growth Performance, Intestinal Microbiota, Liver and Intestine Histopathology of Cyprinus carpio

Abstract This study aimed to evaluate the effects of Mentha piperita methanolic extract (MPE) on Cyprinus carpio intestinal microbiota, including total microorganisms gram-negative bacteria, lactic acid bacteria, and fungi count. Liver and intestinal histopathology, and the activity of liver enzymes, were also used to evaluate the possible side effects of MPE. A total of 96 healthy C. carpio fries (76.76±20.26 g) were allocated to four treatment groups with three replications in a completely randomized design. The fries were fed with diets containing 0, 0.5, 1, and 2% extract for 56 days at the rate of 2% of body weight during the experiment. Results showed a significant decrease in total microorganisms, enteric gram-negative bacteria, and total fungi counts (p<0.05). The total lactic acid bacteria count in 0.5% treatment was significantly lower than in control and 2% treated fish (P<0.05). MPE did not affect AST, leading to a significant increase in ALT levels. Simultaneously, ALP represented significantly higher activity in the control group (P>0.05). Microscopic findings revealed marked lesions, including congestion and cell degeneration in the livers of the three groups of fish fed with the extract. The intestinal folds were shortened and blunted in the treatment groups. Furthermore, the intestinal mucosa was necrotic, and the lamina propria was significantly thickened with mononuclear inflammatory cells (P<0.05). Although MPE significantly affects intestinal microbiota, its consumption at 2% is not recommended for C. carpio due to the lesions made in the liver and intestine.

Microbial Characteristics of Lower Respiratory Tract Infections in Patients Referred from Primary Care Hospitals

Objective: This study investigated the microbiological characteristics of severe lower respiratory tract infection patients not respond to initial treatment, and were transferred to a tertiary-level hospital.Material and Methods: This was a multicenter, prospective study conducted across four hospitals: Cho Ray, Pham Ngoc Thach, Gia Dinh People’s Hospital, and Can Tho Central General Hospital. Sputum specimens were collected shortly after admission and subjected to culture and real-time PCR testing.Results: Out of the 252 patients, 170 (67.4%) met the criteria for analysis and identification of pathogenic microorganisms. The most frequently isolated pathogens were Streptococcus pneumoniae (S. pneumonia) and Haemophilus influenzae (H. influenzae), comprising of 27.0% and 13.1%, respectively. Antibiotic susceptibility testing was conducted on 55 patients (32.3%). Among these cases, there were 16 instances of S. pneumoniae, 10 cases of Staphylococcus aureus (S. aureus), 10 cases of Pseudomonas aeruginosa (P. aeruginosa), 14 cases of gram-negative enteric bacteria, 2 cases of H. influenzae, 1 case of Moraxella catarrhalis (M. catarrhalis), 1 case of Enterococcus faecium, and 1 case of M. pneumoniae. The antibiogram results revealed significant findings; including a 70% prevalence of extended-spectrum beta-lactamase and 90% occurrence of Methicillin-Resistant Staphylococcus aureus. The data also indicated high resistance rates; such as 90% resistance to erythromycin, 40-80% to ciprofloxacin, 30-80% to ceftazidime, and 30-40% to imipenem.Conclusion: Pathogens associated with LRTIs referred from primary care hospitals encompass S. pneumonia, H. influenza, and S. aureus. At our facility, piperacillin, imipenem, amikacin, vancomycin, and linezolid emerged as the most effective antibiotics for addressing these LRTIs. 

Recombinase Polymerase Amplification Assay for Rapid Field Diagnosis of Stewart’s Wilt of Corn Pathogen Pantoea stewartii subsp. stewartii

Stewart’s vascular wilt and leaf blight of sweet corn is caused by the Gram-negative enteric bacterium Pantoea stewartii subsp. stewartii. Stewart’s wilt results in substantial yield losses worldwide warranting rapid and accurate disease diagnosis. Recombinase polymerase amplification (RPA) is an isothermal technique that is tolerant to host plant-derived inhibitors and is, therefore, ideally suited for rapid in-field detection vis-à-vis traditional polymerase chain reaction-based molecular assays. An RPA assay coupled with a Lateral Flow Device (LFD) was developed for rapid, accurate, and sensitive real-time detection of P. stewartii subsp. stewartii directly from the infected host offering in-field pathogen detection, timely disease management, and satisfying quarantine and phytosanitary requirements. Twelve novel primer sets were designed against conserved genomic regions of P. stewartii subsp. Stewartii; however, only the primers for amplification of the intergenic spacer region between capsular polysaccharide genes cpsA and cpsB were discernibly unique and adequate for unambiguous identification of P. stewartii subsp. stewartii. The P. stewartii subsp. stewartii-specific primers were further validated in a simplex RPA assay for specificity against twenty-six bacterial species representing several Pantoea and other closely related bacterial species/subspecies/strains found in the same niche, and naturally or artificially infected plant samples. The integrated RPA/LFD assay was also optimized for rapid and sensitive on-site detection of P. stewartii subsp. stewartii with an empirical detection limit of 0.0005 pg μL−1 bacterial DNA and 1 × 102 CFU mL−1 (app. two bacterial cells used per RPA reaction) in minimally processed samples for accurate, low-cost, and point-of-need diagnosis of the quarantine pathogen P. stewartii subsp. stewartii.

Periprosthetic infection after total hip arthroplasty in polytrauma victims

Infectious complications during endoprosthesis of large joints are one of the urgent medical and socio-economic problems of modern orthopedics and traumatology. The purpose of the study was to improve the results of treatment of periprosthetic infection in patients after total hip arthroplasty as a result of polytrauma by determining the features of the course and diagnosing it in this category of patients. To carry out the study, a retrospective analysis of 87 cases of periprosthetic infection was conducted in patients undergoing inpatient treatment at the Kyiv City Clinical Hospital of Emergency Medical Care for the period 2012–2020 and divided into observation and control groups. Іn the first group, acute postoperative periprosthetic infection (up to 4 weeks) was detected in 33 victims, which was 71.7% of the group. In the second group, this type of periprosthetic infection was detected in 23 victims, which was 56.1% of the group. Late chronic infection (from 4 weeks to 1 year) among the victims of the first group was found in 10 patients, which was 21.7% of the group. In the second group, there were 11 patients with late periprosthetic infection, which was 24.4% of the group. All patients participating in the study were divided into observation and control groups. Periprosthetic infection after total hip arthroplasty in polytrauma victims develops more often in the early stages, up to 4 weeks. In addition to gram-positive cocci, the causes of periprosthetic infection are often gram-negative enterobacteria, which indicates the prevalence of the endogenous route of infection in this category of patients. Among the etiological factors of periprosthetic infection after total hip arthroplasty in polytrauma victims, Acinetobacter spp. is quite often found, which is a consequence of long-term use of invasive methods of treatment and monitoring performed on the patient during the treatment of traumatic injuries. Keywords: large joints, arthroplasty, microorganisms, complications, multiple trauma.

Evaluation of the liquid colony for identification and antimicrobial susceptibility testing directly from positive blood cultures

BackgroundSepsis represents a time-sensitive disease requiring early therapeutical intervention to avoid adverse patient outcomes. Rapid microbiological diagnosis is essential to investigate sepsis aetiological agents. The FAST™ system (Qvella, ON, Canada) provides a concentrated microbial suspension, known as a Liquid Colony™ (LC), directly from positive blood samples (PBCs) in 30–40 min to perform rapid identification (ID) and antimicrobial susceptibility testing (AST).MethodsQvella’s FAST™ System and FAST PBC Prep cartridges were tested on PBCs from the Policlinico Hospital of Catania during a six-month study. Two millilitres of PBC were converted into an LC for rapid ID and AST using Bruker Biotyper Sirius MALDI and BD Phoenix systems. Standard of care (SOC) methods were used as a reference, requiring 48–72 h. Agreement between the innovative technology and the standard method was calculated.ResultsFAST System processing was performed on 100 monomicrobial PBCs. Median turnaround times from blood cultures flagging positive to ID and AST completion were 2 and 26 h respectively. Therefore, the LC procedure was 24 h faster than the median turnaround times for SOC methods. 100% ID identification concordance was observed across 48 Gram-negative bacteria, 42 Gram-positive bacteria and 11 yeast for the genus level. 78% of Gram-negative and 95% of Gram-positive bacteria were resistant to ≥ 2 antimicrobial agents, including 45% (15/33) carbapenem-resistant enteric Gram-negative bacteria and 90% (28/31) oxacillin-resistant staphylococci. An AST essential agreement of 100% was observed due to the absence of MIC discrepancies > 1-fold dilution. Categorical errors were not observed due to the absence of MIC categorization discordances. Yeast AST was not performed.ConclusionsThe Qvella FAST System produces an LC that reliably reflects the MALDI spectra and phenotypic antimicrobial susceptibility profile of microbial cells growing in the blood culture. Timely processing of PBCs with the Qvella FAST System enables sepsis diagnostic confirmation 1 day sooner than the standard methods. In line with these results, it is vital now to focus attention on establishing best practices for incorporating this strategic tool into the clinical microbiology laboratory workflow.

Distribution of Bacterial Species and Resistance Patterns in Surgical Site Infection after Prior Administration of Vancomycin and Tobramycin Intrawound Powdered Antibiotic Prophylaxis.

Evaluate the species distribution and resistance patterns of bacterial pathogens causing surgical site infection (SSI) after operative fracture repair, with and without the use of intrawound powdered antibiotic (IPA) prophylaxis during the index surgery. Retrospective cohort study. Academic, level 1 trauma center, 2018-2020. Fifty-nine deep SSIs were identified in a sample of 734 patients with 846 fractures (IPA [n = 320], control [n = 526]; open [n = 157], closed fractures [n = 689]) who underwent orthopaedic fracture care. Among SSIs, 28 (48%) patients received IPA prophylaxis and 25 (42%) of the fractures were open. Intrawound powdered vancomycin and tobramycin. Distribution of bacterial species and resistance patterns causing deep surgical site infections requiring operative debridement. Zero patients developed infections caused by resistant strains of streptococci, enterococci, gram-negative enterics, Pseudomonas , or Cutibacterium species. The only resistant strains isolated were methicillin resistance (19%) and oxacillin-resistant coagulase-negative staphylococci (16%). There was no associated statistical difference in the proportion of bacterial species isolated, their resistance profiles, or rate of polymicrobial infections between the IPA and control group. Most (93%) cases using IPAs included vancomycin and tobramycin powders. There were 59 SSIs; 28 (9%) in the IPA cohort and 31 (6%) in the control cohort ( P = 0.13). The use of local antibiotic prophylaxis resulted in no measurable increase in the proportion of infections caused by resistant bacterial pathogens after operative treatment of fractures. However, the small sample size and limited time frame of these preliminary data require continued investigation into their role as an adjunct to SSI prophylaxis. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Conditions Necessary for the Transfer of Antimicrobial Resistance in Poultry Litter.

Animal manures contain a large and diverse reservoir of antimicrobial resistance (AMR) genes that could potentially spillover into the general population through transfer of AMR to antibiotic-susceptible pathogens. The ability of poultry litter microbiota to transmit AMR was examined in this study. Abundance of phenotypic AMR was assessed for litter microbiota to the antibiotics: ampicillin (Ap; 25 μg/mL), chloramphenicol (Cm; 25 μg/mL), streptomycin (Sm; 100 μg/mL), and tetracycline (Tc; 25 μg/mL). qPCR was used to estimate gene load of streptomycin-resistance and sulfonamide-resistance genes aadA1 and sul1, respectively, in the poultry litter community. AMR gene load was determined relative to total bacterial abundance using 16S rRNA qPCR. Poultry litter contained 108 CFU/g, with Gram-negative enterics representing a minor population (<104 CFU/g). There was high abundance of resistance to Sm (106 to 107 CFU/g) and Tc (106 to 107 CFU/g) and a sizeable antimicrobial-resistance gene load in regards to gene copies per bacterial genome (aadA1: 0.0001-0.0060 and sul1: 0.0355-0.2455). While plasmid transfer was observed from Escherichia coli R100, as an F-plasmid donor control, to the Salmonella recipient in vitro, no AMR Salmonella were detected in a poultry litter microcosm with the inclusion of E. coli R100. Confirmatory experiments showed that isolated poultry litter bacteria were not interfering with plasmid transfer in filter matings. As no R100 transfer was observed at 25 °C, conjugative plasmid pRSA was chosen for its high plasmid transfer frequency (10-4 to 10-5) at 25 °C. While E. coli strain background influenced the persistence of pRSA in poultry litter, no plasmid transfer to Salmonella was ever observed. Although poultry litter microbiota contains a significant AMR gene load, potential to transmit resistance is low under conditions commonly used to assess plasmid conjugation.

A Single Residue within the MCR-1 Protein Confers Anticipatory Resilience.

The envelope stress response (ESR) of Gram-negative enteric bacteria senses fluctuations in nutrient availability and environmental changes to avert damage and promote survival. It has a protective role toward antimicrobials, but direct interactions between ESR components and antibiotic resistance genes have not been demonstrated. Here, we report interactions between a central regulator of ESR viz., the two-component signal transduction system CpxRA (conjugative pilus expression), and the recently described mobile colistin resistance protein (MCR-1). Purified MCR-1 is specifically cleaved within its highly conserved periplasmic bridge element, which links its N-terminal transmembrane domain with the C-terminal active-site periplasmic domain, by the CpxRA-regulated serine endoprotease DegP. Recombinant strains harboring cleavage site mutations in MCR-1 are either protease resistant or degradation susceptible, with widely differing consequences for colistin resistance. Transfer of the gene encoding a degradation-susceptible mutant to strains that lack either DegP or its regulator CpxRA restores expression and colistin resistance. MCR-1 production in Escherichia coli imposes growth restriction in strains lacking either DegP or CpxRA, effects that are reversed by transactive expression of DegP. Excipient allosteric activation of the DegP protease specifically inhibits growth of isolates carrying mcr-1 plasmids. As CpxRA directly senses acidification, growth of strains at moderately low pH dramatically increases both MCR-1-dependent phosphoethanolamine (PEA) modification of lipid A and colistin resistance levels. Strains expressing MCR-1 are also more resistant to antimicrobial peptides and bile acids. Thus, a single residue external to its active site induces ESR activity to confer resilience in MCR-1-expressing strains to commonly encountered environmental stimuli, such as changes in acidity and antimicrobial peptides. Targeted activation of the nonessential protease DegP can lead to the elimination of transferable colistin resistance in Gram-negative bacteria. IMPORTANCE The global presence of transferable mcr genes in a wide range of Gram-negative bacteria from clinical, veterinary, food, and aquaculture environments is disconcerting. Its success as a transmissible resistance factor remains enigmatic, because its expression imposes fitness costs and imparts only moderate levels of colistin resistance. Here, we show that MCR-1 triggers regulatory components of the envelope stress response, a system that senses fluctuations in nutrient availability and environmental changes, to promote bacterial survival in low pH environments. We identify a single residue within a highly conserved structural element of mcr-1 distal to its catalytic site that modulates resistance activity and triggers the ESR. Using mutational analysis, quantitative lipid A profiling and biochemical assays, we determined that growth in low pH environments dramatically increases colistin resistance levels and promotes resistance to bile acids and antimicrobial peptides. We exploited these findings to develop a targeted approach that eliminates mcr-1 and its plasmid carriers.

A Dietary Nucleoside-Nucleotide Mixture Inhibits Endotoxin-Induced Bacterial Translocation in Mice Fed Protein-Free Diet

Nucleosides and nucleotides are important substrates utilized by the intestinal mucosa. To determine the relative effect of dietary nucleosides and nucleotides on the gut, we investigated the effects of these compounds on endotoxin-induced bacterial translocation, cecal bacterial populations and ileal histology in protein-malnourished mice. There was an inhibition of gram-negative enteric bacteria in the mesenteric lymph node and spleen of the surviving mice fed the protein-free diet supplemented with a nucleoside-nucleotide mixture compared with the nonsupplemented group. Histologically, the damage to the gut mucosal barrier was more pronounced in the nonsupplemented group than in the nucleoside-nucleotide supplemented group. However, the cecal bacterial populations in the groups were not different. The villous height, crypt depth and total wall thickness were more developed in the supplemented group compared with the nonsupplemented group, indicating that the nucleoside-nucleotide mixture blocked bacterial translocation by preventing endotoxin-induced mucosal or epithelial damage. These results suggest that the nucleoside-nucleotide mixture could be used to inhibit or reduce the incidence of bacterial translocation, decrease intestinal injury and improve survival in a lethal model of protein deficiency and endotoxemia.

Electrostatic interactions mediate the nucleation and growth of a bacterial functional amyloid.

Bacterial biofilm formation can have severe impacts on human and environmental health. Enteric bacteria produce functional amyloid fibers called curli that aid in biofilm formation and host colonization. CsgA is the major proteinaceous component of curli amyloid fibers and is conserved in many gram-negative enteric bacteria. The CsgA amyloid core consists of five imperfect repeats (R1-R5). R2, R3, and R4 have aspartic acid (D) and glycine (G) residues that serve as "gatekeeper" residues by modulating the intrinsic aggregation propensity of CsgA. Here, using mutagenesis, salt-mediated charge screening, and by varying pH conditions, we show that the ability of CsgA variants to nucleate and form amyloid fibers is dictated by the charge state of the gatekeeper residues. We report that in Citrobacter youngae CsgA, certain arginine (R) and lysine (K) residues also act as gatekeeper residues. A mechanism of gatekeeping is proposed wherein R and K residues electrostatically interact with negatively charged D residues, tempering CsgA fiber formation.

Isolation and identification of bacterial causes of diarrhea in children less than 2 years old in Al-Muthanna Governorate

Diarrhea is the second leading cause of children’s death under five years of age worldwide. The most common microbiological causes of gastroenteritis vary by age group, geographic region, and type of diarrhea. This study designed to identify the bacterial causes of children’s diarrhea under two years of age in Samawah /Al-Muthanna Governorate. Out of 84 patients, 21 sterile stool swabs were collected from children suffering from diarrhea in the Maternity and Children Hospital in Samawah for the period from 1 to 31 December 2021. Samples were cultured on selective diagnostic culture media. Antibiotic sensitivity test was performed for bacterial isolates using discs diffusion test. Out of 84 total hospitalized child, there were 61 (72.61%) children with diarrhoea. Whereas, the percentages of other diseases were 2% (2.38), 16 (19.04), 3 (3.57%), 1% (1.19%), 1 (1.19%) and 1% (1.19%) for jaundice, bronchitis, dyspnea and asthma, suckling interruption, hypoglycemia and pneumonia, respectively. According to age, the highest percentage of diarrhea 24(39.344%) was recorded in children less than one month. Moreover, the number and percentages of diarrhea at ages 2, 3, 4, 6, 5 7, 8, 9, 10, 11, 12 and 24 months were as follows: 5 (8.196%), 3 (4.918%), 4 (6.557%), 4 (6,557%), 2 (3.278%), 4 (6.557 %), 0.%, 3 (4.918%), 3 (4.918 %), 0%, 6 (9.83%) and 3 (4.918%) respectively. The total percentage of bacterial isolation was 100%, that comprised 38.10%, 14.29%, 4.76 %, 9.52 %, 23.81%, and 9.52% for E. coli, Salmonella typhi, Salmonella typhimurium, Klebsiella, Shigella sp., and Proteous sp. respectively. In conclusion, this study approved that multiple-drug resistant, gram-negative enterobacteria were the causes of diarrhea in children under-age of two years.

Evaluation of Blood Stream and Biliary Tract Infections Related to Percutaneous Transhepatic Cholangiography and Prophylaxis Given in Patients with Malignancy.

Percutaneous transhepatic cholangiography (PTC) is an invasive procedure used in patients with obstructive jaundice in the progress of some malignancies, and its most common complication is infection. We aimed to evaluate the patients who underwent PTC regarding their cultures, prophylaxis, and antibiotics used for treatment. In this cross-sectional study, patients who underwent PTC and were followed up in a medical oncology outpatient clinic between 2010-2017 were evaluated retrospectively. Patients' data were obtained from the hospital record system (FONET), epicrisis forms, and patient progress files. A total of 93 patients were included in the study. Prophylaxis was given in 50% of the cases. Complications developed in 68% of the cases after the intervention, and the infectious disease clinic consulted all. Blood cultures were obtained from 89% of the febrile patients; however, bile cultures were obtained only from 29%. The rate of resistant Gram-negative enteric bacteria in growing microorganisms was 52% (n=13). It was determined that 65% of the initiated empirical treatments were appropriate for the growth of microorganisms. The growth rate was significantly higher in blood cultures than in bile cultures. The lower growth rate in bile culture was attributed to the low number of bile cultures. There was no significant difference regarding the growth rate and drug resistance of the microorganisms. Therefore, we think giving antibiotics as treatment rather than prophylaxis is more appropriate. Taking cultures will ensure that patients receive appropriate antibiotic therapy for the causative agent.

A Familiar Outbreak of Monophasic Salmonella serovar Typhimurium (ST34) Involving Three Dogs and Their Owner's Children.

Salmonella is a Gram-negative enteric bacterium responsible for the foodborne and waterborne disease salmonellosis, which is the second most reported bacterial zoonosis in humans. Many animals are potential sources of salmonellosis, including dogs, cats, and other pets. We report the case of an outbreak of salmonellosis in a family in central Italy, affecting two children and involving their three dogs as carriers. One of the children needed medical care and hospitalisation. Isolation and analysis of stool samples from the sibling and the animals present in the house were carried out. Serotyping allowed the identification of S. enterica subsp. enterica serovar Typhimurium in its monophasic variant for all the isolates. The results of whole-genome sequencing confirmed that the strains were tightly related. The minimum inhibitory concentration (MIC) test documented the resistance to ampicillin, sulfamethoxazole, and tetracycline. The origin of the zoonotic outbreak could not be assessed; however, the case study showed a clear passage of the pathogen between the human and non-human members of the family. The possibility of a transmission from a dog to a human suggests the need for further studies on the potential ways of transmission of salmonellosis through standard and alternative feed.

Modified nutrient medium for isolation and identification of non-fermenting bacteria

The relevance of this study is due to the need for laboratory monitoring of the circulation of gram-negative non-fermenting bacteria that have a high etiological significance in the occurrence of nosocomial infections, as well as the complexity of differentiating these bacteria on simple nutrient media from representatives of enterobacteria and between individual representatives of gram-negative non-fermenting bacteria.&#x0D; The purpose of this study was to design a differential diagnostic medium containing domestic ingredients.&#x0D; Materials and methods. The growth efficiency of test strains on comparable nutrient media, their cultural and morphological characteristics were determined.&#x0D; Results. The modified culture medium makes it possible to distinguish test strains of gram-negative non-fermenting bacteria from test strains of other bacteria (gram-negative enterobacteria, Staphylococcus), and between these strains by the color of the colonies and growth patterns. This feature gives the opportunity to apply modified medium for the differentiation of non-fermentative bacteria from fermenting ones and, simultaneously, for the primary differentiation of different representatives of non-fermenting bacteria by changing the color of the medium and different color of colonies.

S3525 A Rare Case of Campylobacter and Strongyloides stercoralis Co-infection in an Immunocompetent Host

Introduction: Strongyloides stercoralis is a parasitic nematode mainly seen in immigrants and military personnel from endemic areas. Most cases in immunocompetent hosts are incidental findings or present with mild gastrointestinal (GI), respiratory or dermal symptoms. Co-infection with organisms like Campylobacter coupled with anatomical abnormalities such as a hiatal hernia can produce similar symptoms delaying diagnosis and treatment. Case Description/Methods: A 75 year-old-woman presented with persistent watery diarrhea, nausea, dyspepsia, and non-bloody and non-bilious vomiting over the past five days. She also had an unintentional weight loss of 50 pounds over the past three months. She denied any recent travel, rashes, or fevers/chills. On presentation, she was hemodynamically stable with generalized abdominal tenderness on physical exam. CT of the abdomen revealed a moderately-sized hiatal hernia. Serologies were significant for normocytic anemia, thrombocytosis, and eosinophilia (white blood cell count 5300, eosinophils 6.6%). Stool studies were positive for Campylobacter and she was started on azithromycin. She initially felt better and was subsequently discharged on azithromycin. She then presented three days later with complaints of nausea, and bloody emesis. Upper endoscopy with biopsy was done which showed a Los Angeles grade D reflux esophagitis and duodenitis. Histological evaluation revealed S. stercoralis in the duodenal mucosa (Figure 1). Initial ova and parasite cultures from a week ago further confirmed the diagnosis. She was then started on an extended course of ivermectin with a resolution of her symptoms and was discharged home. Discussion: Campylobacter is an enteric gram-negative bacterium that also affects the GI tract and can mimic S. stercoralis infection clinically. Co-infection with this organism occurs due to its similar mode of transmission, however, there have only been a few cases documented in literature. Diagnosis is made by stool testing and serology, however, stool tests are only positive in 50-60% of cases. Eosinophilia may or may not be present. Clinicians should be aware that despite having underlying structural abnormalities such as a hiatal hernia, an EGD with biopsy is warranted to rule out infectious etiologies especially in the presence of eosinophilia as seen above. Early diagnosis and treatment are essential in preventing disseminated disease, especially in immunocompromised patients.Figure 1.: Hematoxylin and Eosin stain of the duodenum revealing acute duodenitis with associated Strongyloides stercoralis in the intestinal crypts and lumen.