Colonization Factor Research Articles

Vibrio cholerae CsrA controls ToxR levels by increasing the stability and translation of toxR mRNA

ABSTRACT Intestinal colonization and virulence factor production in response to environmental cues is mediated through several regulatory factors in Vibrio cholerae , including the highly conserved RNA-binding global regulatory protein CsrA. We have shown previously that CsrA increases synthesis of the virulence-associated transcription factor ToxR in response to specific amino acids (NRES) and is required for the virulence of V. cholerae in the infant mouse model of cholera. In this study, we mapped the 5′ untranslated region (5′ UTR) of toxR and showed that CsrA can bind directly to an RNA sequence encompassing the 5′ UTR, indicating that the regulation of ToxR levels by CsrA is direct. Consistent with this observation, the 5′ UTR of toxR contains multiple putative CsrA binding sequences (GGA motifs), and mutating these motifs disrupted the CsrA-mediated increase in ToxR. Optimal binding of CsrA to a defined RNA oligonucleotide required the bridging of two GGA motifs within a single RNA strand. To determine the mechanism of regulation by CsrA, we assayed toxR transcript levels, stability, and efficiency of translation. Both the amount of toxR mRNA in NRES and the stability of the toxR transcript were increased by CsrA. Using an in vitro translation assay, we further showed that synthesis of ToxR was greatly enhanced in the presence of purified CsrA, suggesting a direct role for CsrA in the translation of toxR mRNA. We propose a model in which CsrA binding to the 5′ UTR of the toxR transcript promotes ribosomal access while precluding interactions with RNA-degrading enzymes. IMPORTANCE Vibrio cholerae is uniquely adapted to marine environments as well as the human intestinal tract. Global regulators, such as CsrA, which help translate environmental cues into an appropriate cellular response, are critical for switching between these distinct environments. Understanding the pathways involved in relaying environmental signals is essential for understanding both the environmental persistence and the intestinal pathogenesis of this devastating human pathogen. In this study, we demonstrate that CsrA directly regulates the synthesis of ToxR, a key virulence factor of V. cholerae . Under conditions favoring high levels of active CsrA in the cell, such as in the presence of particular amino acids, CsrA increases ToxR protein levels by binding to the toxR transcript and enhancing both its stability and translation. By responding to nutrient availability, CsrA is perfectly poised to activate the virulence gene regulatory cascade at the preferred site of colonization in the human host, the nutrient-rich small intestinal mucosa.

Bacterial small RNA makes a big impact for gut colonization

The functions of non-coding small RNAs (sRNAs) within the human microbiome remain largely unexplored. In this Cell Host & Microbe issue, El Mouali etal. identify Segatella RNA colonization factor (SrcF), a sRNA from a prevalent gut bacterium Segatella copri. SrcF promotes colonization of S.copri by regulating bacterial degradation of complex dietary carbohydrates.

Protection of Rabbits Against Colonization and Morbidity Associated With Toxigenic Pasteurella multocida by Immunization With Inactivated Heat-labile Toxin.

Pasteurella multocida is a significant cause of morbidity and mortality in rabbits, as well as other species. Some isolates elaborate a heat-labile toxin (PMT) that has been shown to be an important virulence factor. Though previous studies have demonstrated protective immunity can be conferred via immunization of rabbits with heat-inactivated PMT (IPMT), we investigated the ability of immunization to impact colonization of P. multocida. Rabbits were immunized at days 0, 7 and 14 with either phosphate buffered saline (PBS), the mucosal adjuvant cholera toxin (CT), IMPT or IPMT + CT. Male New Zealand white rabbits were used and confirmed to be free of P. multocida prior to experimentation. Serum IgG and nasal lavage fluid IgA responses directed against PMT were found in rabbits immunized with IPMT, with or without CT, but not in those immunized with only PBS or CT; and the addition of CT to IPMT enhanced the response. Significantly more P. multocida CFUs (p≤0.05) were cultured from the lungs of rabbits immunized with IPMT, with or without CT, compared to those administered only PBS or CT, although no differences were observed in nasal lavage fluid samples. Further, immunization IPMT, with or without CT, conferred protection against pleuritis and pneumonia. PMT, in addition to its role as a virulence factor, may serve as a colonization factor for P. multocida in the lungs of rabbits.

Is routine screening for Candida auris necessary in ICU?

The capability to cause invasive infection, multi-drug resistance, and health care-associated outbreaks of Candida auris have made it a pathogen of great concern. Estimating how many patients in our intensive care unit had C. auris colonization and what characteristics put patients at risk for having Candida spp. colonization were the primary goals of the study. Swabs from axilla and groin were collected from 229 patients getting admitted to the ICU. Samples were inoculated into CHROMagarTM Candida Plus medium. Colonies presumptively identified as C. auris by the presence of light blue with blue halo and were confirmed by VITEK-2. Our study showed that only one patient was colonized with C. auris. A total of 47 (20.5%) patients were colonized with Candida spp., of which Candida parapislosis was the predominant organism. History of antibiotic use and cerebrovascular accident were independent risk factors in Candida colonization. Active screening for Candida auris in all patients is not required in our hospital as the prevalence was very low and not cost-effective. Therefore we plan to modify our screening strategy and use risk factors based surveillance strategy as it may serve as an ideal strategy.

Risk factors for bacterial stent colonization in patients with a double J ureteral stent: a prospective study

Background: The increasing use of double-J ureteral stents (DJS) has increased the risk of early intolerance and long-term complications. Studies have reported stent colonization rates ranging from 19% to 90% with various bacterial profiles in the colonization of stents. Objectives: To identify the risk factors associated with bacterial colonization of DJS and report the common microorganisms isolated and drug susceptibility pattern. Methods: This study is a prospective study of patients who underwent DJS. A total of 48 patients from our institution were studied between March 2022 and August 2023. After removal of DJS with a sterile technique, the tips of both ends (renal end and bladder end) of the stent were cut and processed in the microbiology lab. Results: Bacterial colonies were detected in 56.25% (27 out of 48) of the stents. Among the pathogens identified, Enterococcus species, Pseudomonas Aeruginosa and E. coli were the most frequently isolated. The colonization rate increased with the duration of stent placement and albuminuria. Conclusions: The study indicated that prolonged indwelling time and albuminuria are a risk factor for bacterial colonization on the stent therefore, it is advisable to use Double J ureteral stent only when absolutely necessary and to remove them promptly.

Pathogenicity of Citrobacter freundii Causing Mass Mortalities of Macrobrachium rosenbergii and Its Induced Host Immune Response.

Citrobacter freundii is an opportunistic pathogen of freshwater aquatic animals, which severely restricts the sustainable development of the aquaculture industry. In this study, a dominant strain, named FSNM-1, was isolated from the hepatopancreas of diseased Macrobrachium rosenbergii. This strain was identified as C. freundii based on a comprehensive analysis of its morphological, physiological, and biochemical features and molecular identification. Challenge experiments were conducted to assess the pathogenicity of C. freundii to M. rosenbergii. The results showed that the FSNM-1 strain had high virulence to M. rosenbergii with a median lethal dose (LD50) of 1.1 × 106 CFU/mL. Histopathological analysis revealed that C. freundii infection caused different degrees of inflammation in the hepatopancreas, gills, and intestines of M. rosenbergii. The detection of virulence-related genes revealed that the FSNM-1 strain carried colonization factor antigen (cfa1, cfa2), ureases (ureG, ureF, ureD, ureE), and outer membrane protein (ompX), and virulence factor detection showed that the FSNM-1 strain had lecithinase, amylase, lipase, gelatinase, and hemolysin activities but did not produce protease and DNase activities. To investigate the immune response of M. rosenbergii to C. freundii, the expression levels of ALF3, MyD88, SOD, proPO, TRAF6, and TNF immune-related genes were monitored at different points of time in the hepatopancreas, gills, intestines, and hemocytes of M. rosenbergii after infection. The results demonstrated a significant upregulation in the expression levels of the ALF3, MyD88, SOD, proPO, TRAF6, and TNF genes in M. rosenbergii at the early stage of C. freundii infection. This study highlights C. freundii as a major pathogen causing mass mortality in M. rosenbergii and provides valuable insights into its virulence mechanisms and the host's immune response.

Epidemiology of Diarrheagenic Escherichia coli: A Mini Review

Diarrheal diseases are a significant public health challenge, leading to high numbers of morbidity and mortality globally. Diarrheagenic Escherichia coli (DEC) strains exhibit a complex spectrum, ranging from benign gut inhabitants to severe pathogens causing intestinal and extraintestinal diseases. This review focuses on elucidating DEC epidemiology, emphasizing research conducted worldwide. A comprehensive review searched for relevant studies on DEC's impact, using keywords like "diarrheagenic Escherichia coli," "DEC pathotypes," and "epidemiology" in databases like PubMed. Inclusion criteria covered 67 studies on virulence, pathogenesis, detection, and geographic diversity. Studies globally indicate variable prevalence rates for DEC. Enteropathogenic E. coli is prominent in Bangladesh (17.2% prevalence), relying on intimin, Bundle-forming pilus, and the locus of enterocyte effacement (LEE) pathogenicity island. Enterohemorrhagic E. coli, prevalent in the US and Europe (up to 1.5% outbreak rates in the US), utilizes Shiga toxin and the LEE pathogenicity island. Enteroaggregative E. coli, notably in Africa (Kenya, 13.5% prevalence), employs multilocus enzyme electrophoresis analysis, Escherichia coli heat-stable enterotoxin 1 (EAST-1), adherence mechanisms, and biofilm formation. Enterotoxigenic E. coli is highly prevalent in South Asia and Sub-Saharan Africa (Bangladesh, 6% prevalence), producing colonization factors and enterotoxins. Enteroinvasive E. coli is common in Asian developing countries like Bangladesh, relying on invasion genes and a large plasmid. Conversely, Europe exhibits notably low prevalence rates, with Enterohemorrhagic E. coli prevalence falling below 1%, especially in the UK. This review underscores the global prevalence of DEC, emphasizing the need for a global approach to disease management. Understanding the distinct virulence factors and pathogenesis of various DEC pathotypes is crucial for developing targeted interventions

Quinoa ameliorates polycystic ovary syndrome via regulating gut microbiota through PI3K/AKT/mTOR pathway and autophagy

BackgroundPolycystic ovary syndrome (PCOS) is a unity of endocrine and metabolic disorders, associated with PI3K/AKT/mTOR, autophagy, and gut microbiota. Quinoa is a valuable food source, which contains rich minerals, unsaturated fatty acids, and has a positive modulating effect on metabolic diseases. However, its effects and potential mechanisms on PCOS have not been reported yet. Therefore, the purpose of this study is to investigate the effect of quinoa on PCOS rats by regulating PI3K/AKT/mTOR, autophagy, and gut microbiota.MethodsTen–week-old female Sprague-Dawley (SD) rats have received letrozole for 24 days for induction of PCOS and subsequently were treated with a quinoa diet for 8 weeks. Vaginal smears were used to analyze the estrous cycle of rats. Hormone and biochemical indexes were analyzed by kit assays and glucometer. The pathological changes of ovary, pancreas, duodenum and colon were observed by HE staining. PI3K, AKT, mTOR and autophagy-related proteins in the ovary and colon were measured by western blot and immunohistochemistry staining. Tight junction proteins in colon were measured by immunohistochemistry staining. 16 s rDNA sequencing was used to detect the changes of intestinal microbiota in rats. Network pharmacology and molecular docking were used to study the possible targets and mechanisms of quinoa on PCOS. Spearman correlation analysis was used to study the relationship between intestinal microbial abundance and hormone levels of PCOS rats at the phylum and genus level.ResultsQuinoa significantly improved estrous cycle and biochemical parameters of PCOS-like rats, and the pathological state of ovary, pancreas, duodenum and colon tissues. Especially, quinoa significantly regulated the expression of PI3K, AKT, mTOR and autophagy-related proteins in the ovary. Quinoa may repair the intestinal barrier by upregulating the expression of tight junction proteins in the colon, and regulate autophagy-related factors in colon. Additionally, quinoa increased the abundance of Lactobacillu, Bacteroides and Oscillospira, and decreased the Firmicutes/Bacteroidetes ratio and the Blautia, and Prevotella, reversing the dysregulation of the gut microbiota. Correlation analysis showed that there is a strong correlation between gut microbiota with significant changes in abundance and hormone related to PCOS.ConclusionOur result indicated that effect of quinoa on PCOS maybe associated with activation of the PI3K/AKT/mTOR signaling pathway, inhibition of autophagy, and regulation of intestinal flora.

The Type VII Secretion System (T7SSb) contributes to interbacterial competition in a murine model of Group BStreptococcus gastrointestinal colonization

Abstract Background Late-onset (LO) disease caused by Group B Streptococcus (GBS) infection is a significant source of morbidity and mortality in neonates. It is believed that gastrointestinal (GI) colonization with GBS plays an important role in the progression to LO disease, although the host-microbial interactions that facilitate GBS GI colonization are poorly understood. The Type VII secretion system (T7SSb) has been identified in several gram-positive bacteria, and its function depends on a membrane-bound ATPase (EssC) which drives secretion of virulence factors. In GBS, the T7SSb has been shown to contribute to vaginal colonization and brain cytotoxicity. We aimed to identify the role of the T7SSb in GBS GI colonization using a murine model and hypothesize that the T7SSb is necessary for sustained GBS GI colonization. Methods Two bacterial strains were used, a wild-type (WT) GBS of A909 background (serotype Ia) and an isogenic T7SSb mutant GBS strain (essC::Himar1, transposon inserted). Monocolonization and co-cocolonization experiments were performed by orally inoculating preweaning C57BL/6J mice (12-14 days of life) with one or both strains, respectively. Euthanasia was performed, rectal swabs collected, and the GI tract harvested at day 7 post infection. For co-colonization experiments, competitive indices were calculated at day 7 post infection to determine the contribution of T7SSb to GBS GI colonization. For monocolonization experiments, colonization status and bacterial burden at day 7 post infection were measured. Results In cocolonization, WT GBS A909 outcompeted the essC::Himar1 mutant at 7-days post infection with a geometric mean competitive index of 8.8, 95% CI [0.2, 350.1] by rectal swab; 35.7, 95% CI [19.2, 66.3] in the small intestine; 87.6, 95% CI [18.9, 407] in the cecum; and 91.7, 95% CI [33.4, 252] in the colon (Figure 1a). In monocolonization, we noted similar rates of colonization (p=NS, Fisher’s exact test) (Figure 1b) and no difference in bacterial burden (p=NS, 2-way ANOVA test) (Figure 1c) across the GI tract at 7 days post infection. Conclusion Our results suggest that T7SSb plays an important role in GBS bacterial competition in the GI tract but is likely not an essential factor for GBS GI colonization. Further exploration of the role of the T7SSb in interbacterial competition may yield relevant information regarding GI colonization dynamics. Figure 1. Establishing the role of T7SSb in a murine model of GI colonization. (a) Wild type (WT) A909 confers an advantage over an isogenic T7SSb mutant (essC::Himar1) strain in a cocolonization model. Data points represent geometric mean competition indices and error bars represent 95% confidence interval. (b) Colonization status by WT A909 and essC::Himar1 mutant in the GI tract 7-days post infection in monocolonization experiments (p-values represent two-sided Fisher’s exact test). (c) Bacterial burden of monocolonization by WT A909 and essC::Himar1 mutant in the GI tract 7-days post infection (p-values represent 2-way ANOVA test).

Males are at higher risk of colonization and infection with multi-drug-resistant organisms than females

Global rise of multidrug-resistant organisms (MDRO) is alarming and antimicrobial resistance (AMR) poses a significant public health threat globally. Although certain risk factors are known including recent antimicrobial therapy, inappropriate use and hospitalization, the focus on gender-specific aspects in MDRO is scarce. Our aim was to show gender-specific differences in colonization and infections of multiple MDRO and their detection sites. For this multicentre, retrospective cohort study surveillance data between 2015 and 2020 was collected in 86 hospitals of the Helios group, Germany. The following multidrug-resistant bacteria were analysed according to sample site: MRSA, Enterococcus spp., Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Acinetobacter baumannii. Out of the 7,081,708 cases in the database, 187,656 patients were found to be colonized with MDRO (2.65%). A documented infection with MDRO was identified in 33,023 patients (0.466%), with the origin of infection known in 24,231 cases. Male gender was a risk factor for both infection and colonization of any MDRO (p< .001). Males exhibited a higher likelihood of MDRO detection in superficial skin/soft tissue, blood cultures (p < .001), and respiratory samples (p = .002). Additionally, gender-specific differences in MDRO detection site and pathogens were found with slightly higher proportion of MRSA infection in deep skin/soft tissue and respiratory samples for females. Our study reinforces the existing hypothesis that male gender is a risk factor for MDRO, supported by our large dataset. It highlights the need to acknowledge gender-specific MDRO susceptibility in clinical practice.

The Impact of Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection on Colonic Polyp Resection and Factors Influencing Recurrence

The Impact of Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection on Colonic Polyp Resection and Factors Influencing Recurrence

Risk Factors Analysis and Prediction Model Establishment for Carbapenem-Resistant Enterobacteriaceae Colonization: A Retrospective Cohort Study.

The objective of this study was to identify the risk factors associated with Carbapenem-resistant Enterobacteriaceae (CRE) colonization in intensive care unit (ICU) patients and to develop a predictive risk model for CRE colonization. In this study, 121 ICU patients from Fujian Provincial Hospital were enrolled between January 2021 and July 2022. Based on bacterial culture results from rectal and throat swabs, patients were categorized into two groups: CRE-colonized (n = 18) and non-CRE-colonized (n = 103). To address class imbalance, Synthetic Minority Over-sampling Technique (SMOTE) was applied. Statistical analyses including T-tests, Chi-square tests, and Mann-Whitney U-tests were employed to compare differences between the groups. Feature selection was performed using Lasso regression and Random Forest algorithms. A Logistic regression model was then developed to predict CRE colonization risk, and the results were presented in a nomogram. After applying SMOTE, the dataset included 198 CRE-colonized patients and 180 non-CRE-colonized patients, ensuring balanced groups. The two groups were comparable in most clinical characteristics except for diabetes, previous emergency department admission, and abdominal infection. Eight independent risk factors for CRE colonization were identified through Random Forest, Lasso regression, and Logistic regression, including Acute Physiology and Chronic Health Evaluation (APACHE) II score > 16, length of hospital stay > 31 days, female gender, previous carbapenem antibiotic exposure, skin infection, multi-site infection, immunosuppressant exposure, and tracheal intubation. The risk prediction model for CRE colonization demonstrated high accuracy (87.83%), recall rate (89.9%), precision (85.6%), and an AUC value of 0.877. Patients were categorized into low-risk (0-90 points), medium-risk (91-160 points), and high-risk (161-381 points) groups, with corresponding CRE colonization rates of 1.82%, 7.14%, and 58.33%, respectively. This study identified independent risk factors for CRE colonization and developed a predictive model for assessing the risk of CRE colonization.

The RNA landscape of the human commensal Segatella copri reveals a small RNA essential for gut colonization

The bacterium Segatella copri is a prevalent member of the human gut microbiota associated with health and disease states. However, the intrinsic factors that determine its ability to colonize the gut effectively remain largely unknown. By extensive transcriptome mapping of S.copri and examining human-derived samples, we discover a small RNA, which we name Segatella RNA colonization factor (SrcF), and show that SrcF is essential for S.copri gut colonization in gnotobiotic mice. SrcF regulates genes involved in nutrient acquisition, and complex carbohydrates, particularly fructans, control its expression. Furthermore, SrcF expression is strongly influenced by human microbiome composition and by the breakdown of fructans by cohabitating commensals, suggesting that the breakdown of complex carbohydrates mediates interspecies signaling among commensals beyond its established function in generating energy. Together, this study highlights the contribution of a small RNA as a critical regulator in gut colonization.

Association of Race or Ethnicity With Extended-Spectrum Beta-Lactamase Production in Escherichia Coli: A Case Control Study.

There are limited and conflicting data regarding the impact of race or ethnicity on the rate of gram-negative antimicrobial resistance. This study was performed to determine whether there is a difference in extended-spectrum beta-lactamase (ESBL) Escherichia coli infection or colonization in minoritized patients when compared to White patients from a diverse US Midwestern city. A case control study was performed, with controls with non-ESBL E. coli matched 1:1 to patients with ESBL-producing E coli based on age, sex, and ZIP code. A variety of other evidence-based factors for ESBL Enterobacterales infection and colonization were collected via chart review. Multivariate conditional logistic regression assessed the odds of minoritized patients as compared to White patients, while controlling for other common risk factors for ESBL Enterobacterales. A total of 364 matched pairs were included in the analysis. Females were the majority of the sample (91%), with median age of 65 years. The majority of the sample identified as White (73%), followed by Hispanic (14%) and Black (10%). Urine cultures made up the majority of the cultures in the sample (97%), and this was similar between ESBL and non-ESBL groups. While controlling for these risk factors for ESBL E coli, minoritized patients had a statistically significant greater odds of ESBL-producing E coli (odds ratio, 2.53; 95% confidence interval, 1.68-3.82). In our sample, which is demographically similar to the United States, minoritized patients had higher odds of ESBL-producing E coli. Further research on the drivers for this disparity is needed.

Risk Factors for Colonization of Vancomycin-Resistant Enterococci in Patients in the Intensive Care Unit: A single-center Retrospective Study

Background: Patients colonised with vancomycin-resistant enterococci (VRE) remain a problem worldwide, especially in intensive care units (ICU), necessitating the identification of associated risk factors. Understanding these factors is crucial for implementing effective infection control measures. The aim of this single-centre retrospective study was to determine the risk factors for VRE colonisation in patients admitted to medical and surgical ICUs. Methods: We analyzed data from 190 patients admitted to the ICUs between January 2020 and December 2022. Demographic information, clinical characteristics, laboratory results, antimicrobial usage, and comorbidities were obtained from digital patient records. Rectal swabs were collected weekly within 48 hours of ICU admission to detect VRE colonization. Independent risk factors causing VRE colonisation were determined by logistic regression analyses. Results: Out of 190 patients, 54 were colonized with VRE. Significant independent risk factors for VRE colonization included higher APACHE II scores on ICU admission (OR: 1.26, 95% CI: 1.03-1.55, p=0.024), longer hospital stay (OR: 1.25, 95% CI: 1.14-1.36, p

The added value of perineal swabs when screening for asymptomatic methicillin-resistant Staphylococcus aureus colonization and risk factors for perineal carriage

We examined the added value of perineal swabs in addition to nose and throat swabs when screening for Methicillin-resistant Staphylococcus aureus colonization, and risk factors for perineal carriage in 6,642 patients. In our mainly primary care setting, the added value was 9.3%. Patients <3 or ≥80 had the highest risk.

Global transcriptomic network analysis of the crosstalk between microbiota and cancer-related cells in the oral-gut-lung axis.

The diagnosis and treatment of lung, colon, and gastric cancer through the histologic characteristics and genomic biomarkers have not had a strong impact on the mortality rates of the top three global causes of death by cancer. Twenty-five transcriptomic analyses (10 lung cancer, 10 gastric cancer, and 5 colon cancer datasets) followed our own bioinformatic pipeline based on the utilization of specialized libraries from the R language and DAVID´s gene enrichment analyses to identify a regulatory metafirm network of transcription factors and target genes common in every type of cancer, with experimental evidence that supports its relationship with the unlocking of cell phenotypic plasticity for the acquisition of the hallmarks of cancer during the tumoral process. The network's regulatory functional and signaling pathways might depend on the constant crosstalk with the microbiome network established in the oral-gut-lung axis. The global transcriptomic network analysis highlighted the impact of transcription factors (SOX4, TCF3, TEAD4, ETV4, and FOXM1) that might be related to stem cell programming and cancer progression through the regulation of the expression of genes, such as cancer-cell membrane receptors, that interact with several microorganisms, including human T-cell leukemia virus 1 (HTLV-1), the human papilloma virus (HPV), the Epstein-Barr virus (EBV), and SARS-CoV-2. These interactions can trigger the MAPK, non-canonical WNT, and IFN signaling pathways, which regulate key transcription factor overexpression during the establishment and progression of lung, colon, and gastric cancer, respectively, along with the formation of the microbiome network. The global transcriptomic network analysis highlights the important interaction between key transcription factors in lung, colon, and gastric cancer, which regulates the expression of cancer-cell membrane receptors for the interaction with the microbiome network during the tumorigenic process.

Invasive Candida Infections in Neonatal Intensive Care Units: Risk Factors and New Insights in Prevention.

Invasive Candida infections represent a significant cause of morbidity and mortality in neonatal intensive care units (NICUs), with a particular impact on preterm and low-birth-weight neonates. In addition to prematurity, several predisposing factors for Candida colonization and dissemination during NICU hospitalization have been identified, including prolonged exposure to broad-spectrum antibiotics, central venous catheters, parenteral nutrition, corticosteroids, H2 antagonist administration, and poor adherence to infection control measures. According to the literature, the implementation of antifungal prophylaxis, mainly fluconazole, in high-risk populations has proven to be an effective strategy in reducing the incidence of fungal infections. This review aims to provide an overview of risk factors for invasive Candida infections and current perspectives regarding antifungal prophylaxis use. Recognizing and reducing people's exposure to these modifiable risk factors, in conjunction with the administration of antifungal prophylaxis, has been demonstrated to be an effective method for preventing invasive candidiasis in susceptible neonatal populations.

In situ deposition of nanobodies by an engineered commensal microbe promotes survival in a mouse model of enterohemorrhagic E. coli.

Engineered smart microbes that deliver therapeutic payloads are emerging as treatment modalities, particularly for diseases with links to the gastrointestinal tract. Enterohemorrhagic E coli (EHEC) is a causative agent of potentially lethal hemolytic uremic syndrome. Given concerns that antibiotic treatment increases EHEC production of Shiga toxin (Stx), which is responsible for systemic disease, novel remedies are needed. EHEC encodes a type III secretion system (T3SS) that injects Tir into enterocytes. Tir inserts into the host cell membrane, exposing an extracellular domain that subsequently binds intimin, one of its outer membrane proteins, triggering the formation of attaching and effacing (A/E) lesions that promote EHEC mucosal colonization. Citrobacter rodentium (Cr), a natural A/E mouse pathogen, similarly requires Tir and intimin for its pathogenesis. Mice infected with Cr(ΦStx2dact), a variant lysogenized with an EHEC-derived phage that produces Stx2dact, develop intestinal A/E lesions and toxin-dependent disease. Stx2a is more closely associated with human disease. By developing an efficient approach to seamlessly modify the C. rodentium genome, we generated Cr_Tir-MEHEC(ΦStx2a), a variant that expresses Stx2a and the EHEC extracellular Tir domain. We found that mouse pre-colonization with HS-PROT3EcT-TD4, a human commensal E. coli strain (E. coli HS) engineered to efficiently secrete- an anti-EHEC Tir nanobody, delayed bacterial colonization and improved survival after challenge with Cr_Tir-MEHEC(ΦStx2a). This study provides the first evidence to support the efficacy of engineered commensal E. coli to intestinally deliver therapeutic payloads that block essential enteric pathogen virulence determinants, a strategy that may serve as an antibiotic-independent antibacterial therapeutic modality.

Development and validation of systems for genetic manipulation of the Old World tick-borne relapsing fever spirochete, Borrelia duttonii.

Relapsing fever (RF), a vector-borne disease caused by Borrelia spp., is characterized by recurring febrile episodes due to repeated bouts of bacteremia. RF spirochetes can be geographically and phylogenetically divided into two distinct groups; Old World RF Borrelia (found in Africa, Asia, and Europe) and New World RF Borrelia (found in the Americas). While RF is a rarely reported disease in the Americas, RF is prevalent in endemic parts of Africa. Despite phylogenetic differences between Old World and New World RF Borrelia and higher incidence of disease associated with Old World RF spirochete infection, genetic manipulation has only been described in New World RF bacteria. Herein, we report the generation of genetic tools for use in the Old World RF spirochete, Borrelia duttonii. We describe methods for transformation and establish shuttle vector- and integration-based approaches for genetic complementation, creating green fluorescent protein (gfp)-expressing B. duttonii strains as a proof of principle. Allelic exchange mutagenesis was also used to inactivate a homolog of the Borrelia burgdorferi p66 gene, which encodes an important virulence factor, in B. duttonii and demonstrate that this mutant was attenuated in a murine model of RF. Finally, the B. duttonii p66 mutant was complemented using shuttle vector- and cis integration-based approaches. As expected, complemented p66 mutant strains were fully infectious, confirming that P66 is required for optimal mammalian infection. The genetic tools and techniques reported herein represent an important advancement in the study of RF Borrelia that allows for future characterization of virulence determinants and colonization factors important for the enzootic cycle of Old World RF spirochetes.