Opportunistic Infections Research Articles

Integrated analysis of microbiome and metabolome reveals signatures in PDAC tumorigenesis and prognosis.

We conducted a large sample-size pancreatic adenocarcinoma microbiome study using a novel microbiome sequencing method and two metabolomic assays. Two significant outcomes of our analysis are: (i) commensal opportunistic pathogens Staphylococcus aureus, Cutibacterium acnes, and Cutibacterium granulosum were enriched in pancreatic ductal adenocarcinoma (PDAC) tumors compared with normal adjacent tissues, and (ii) worse overall survival was found related to the presence of Ralstonia pickettii_B. Microbial species affect the tumorigenesis, metastasis, and prognosis of PDAC via unique microbe-enzyme-metabolite interaction. Thus, our study highlights the need for further investigation of the potential associations between pancreatic microbiota-derived omics signatures, which may drive the clinical transformation of microbiome-derived strategies toward therapy-targeted bacteria.

The Microbiota and Microbiome in COVID-19 in Adults and Children and Potential Therapeutic Interventions: A Review

The work presented is a comprehensive review of the role of the human microbiota in the context of the COVID-19 pandemic. A diverse microbial community heavily colonizes the human body called the microbiota, with the gut microbiota being the most diverse. The composition of the microbiota varies in different parts of the body and changes with age, diet, and other environmental factors. Emerging evidence suggests that the gut microbiota plays a critical role in modulating the host immune response and may influence the severity of COVID-19. Patients with COVID-19 have significant alterations in their gut and respiratory microbiota, characterized by a depletion of beneficial commensal bacteria and an enrichment of opportunistic pathogens. These changes in microbiota composition are associated with elevated inflammatory markers, a dysregulated immune response, and more severe disease outcomes. In addition, changes in the gut microbiota can affect lung and brain function, influencing the severity of COVID-19 cases and neurological symptoms, as well as long-term neurological complications associated with the disease. Due to the importance of the microbiota in COVID-19, several therapeutic approaches targeting the microbiota have been proposed to improve outcomes in this disease, including fecal microbiota transplantation, probiotic and prebiotic supplementation, postbiotic or microbiota-derived metabolite supplementation, dietary interventions, and lifestyle strategies. Overall, the review highlights the critical role of the human microbiota in the pathogenesis and progression of COVID-19 and the potential of microbiota-targeted interventions to improve patient outcomes. HIGHLIGHTS COVID-19 causes gut microbiota dysbiosis, associated with elevated inflammatory markers, a dysregulated immune response, and more severe disease outcomes. Gut microbiota dysbiosis due to COVID-19 affects lung and brain function, which is associated with the severity of COVID-19 cases. Gut microbiota is crucial in COVID-19, so several strategies have been developed to regulate it in COVID-19 cases, such as fecal microbiota transplantation, probiotics, and prebiotics, among others. GRAPHICAL ABSTRACT

Complete genome sequence of Sphingobacterium multivorum strain FW102 with β-galactosidase activity in drinking fountain water.

Sphingobacterium multivorum is a ubiquitous environmental microbe in nature, particularly abundant in soil and water sources. Recently, S. multivorum has been considered to be a potential opportunistic pathogen in humans. We report the 5,9540,064-bp genome sequence of S. multivorum strain FW102, isolated from drinking fountain water and predicted to have multiple copies of β-galactosidase genes.

Development of two quantitative PCR assays for the detection of emerging opportunistic human pathogens belonging to the genus Phytobacter in routine diagnostics

The genus Phytobacter (fam. Enterobacteriaceae) includes species like Phytobacter diazotrophicus and Phytobacter ursingii, which have emerged as opportunistic human pathogens, particularly affecting vulnerable populations such as pre-term infants and immunocompromised patients. Traditional biochemical and molecular methods have struggled to accurately identify Phytobacter species in clinical diagnostics. This study addresses the issue by developing and validating two quantitative PCR (qPCR) assays using SYBR® Green I and TaqMan® technologies, targeting the nitrogen fixation regulatory gene (nifL) of Phytobacter spp. The SYBR® Green I assay showed a detection limit of a single cell per reaction, while the TaqMan® assay was easier to interpret due to the absence of background noise. These assays, validated with clinical isolates from Brazil, identified multiple new Phytobacter isolates, including a potentially novel species, providing improved diagnostic tools for detecting Phytobacter spp. and aiding in better clinical management.

CodY controls the SaeR/S two-component system by modulating branched-chain fatty acid synthesis in Staphylococcus aureus.

Staphylococcus aureus is a Gram-positive, opportunistic human pathogen that is a leading cause of skin and soft tissue infections and invasive disease worldwide. Virulence in this bacterium is tightly controlled by a network of regulatory factors. One such factor is the global regulatory protein CodY. CodY links branched-chain amino acid sufficiency to the production of surface-associated and secreted factors that facilitate immune evasion and subversion. Our previous work revealed that CodY regulates virulence factor gene expression indirectly in part by controlling the activity of the SaeRS two-component system (TCS). While this is correlated with an increase in membrane anteiso-15:0 and -17:0 branched-chain fatty acids (BCFAs) derived from isoleucine, the true mechanism of control has remained elusive. Herein, we report that CodY-dependent regulation of SaeS sensor kinase activity requires BCFA synthesis. During periods of nutrient sufficiency, BCFA synthesis and Sae TCS activity are kept relatively low by CodY-dependent repression of the ilv-leu operon and the isoleucine-specific permease gene brnQ2. In a codY null mutant, which simulates extreme nutrient limitation, de-repression of ilv-leu and brnQ2 directs the synthesis of enzymes in redundant de novo and import pathways to upregulate production of BCFA precursors. Overexpression of brnQ2, independent of CodY, is sufficient to increase membrane anteiso BCFAs, Sae-dependent promoter activity, and SaeR ~P levels. Our results further clarify the molecular mechanisms by which CodY controls virulence in S. aureus.IMPORTANCEExpression of bacterial virulence genes often correlates with the exhaustion of nutrients, but how the signaling of nutrient availability and the resulting physiological responses are coordinated is unclear. In S. aureus, CodY controls the activity of two major regulators of virulence-the Agr and Sae two-component systems (TCSs)-by unknown mechanisms. This work identifies a mechanism by which CodY controls the activity of the sensor kinase SaeS by modulating the levels of anteiso branched-chain amino acids that are incorporated into the membrane. Understanding the mechanism adds to our understanding of how bacterial physiology and metabolism are linked to virulence and underscores the role virulence in maintaining homeostasis. Understanding the mechanism also opens potential avenues for targeted therapeutic strategies against S. aureus infections.

Concordance of Chest Radiography and Chest Computed Tomography Findings in Patients with Hematologic Malignancy and Invasive Mucormycosis: What Are the Prognostic Implications?

Invasive pulmonary mucormycosis (IPM) is a deadly opportunistic mold infection in patients with hematological malignancies (HM). Radiologic imaging is essential for its timely diagnosis. Here, we compared IPM lesions visualized by chest computed tomography (CCT) and chest X-ray (CXR) and determined the prognostic significance of discordant imaging. Therefore, we reviewed 44 consecutive HM patients with probable/proven IPM at MD Anderson Cancer Center in 2000-2020 who had concurrent CCT and CXR studies performed. All 44 patients had abnormal CCTs and 39 (89%) had anormal CXR findings at IPM diagnosis. However, only 26 patients (59%) showed CCT-matching IPM-suspicious lesions on CXR. Acute Physiology and Chronic Health Evaluation II score > 18 at IPM diagnosis and breakthrough infection to Mucorales-active antifungals were the only independent risk factors for 42-day and/or 84-day mortality. Absence of neutropenia at IPM diagnosis, neutrophil recovery in neutropenic patients, and surgical revision of mucormycosis lesions were protective factors. Although not reaching significance on multivariable analysis, visualization of CCT-matching lesions on CXR was associated with significantly increased 84-day mortality (log-rank test, p = 0.033), possibly as a surrogate of extensive lesions and tissue necrosis. This observation supports the exploration of radiologic lesion kinetics as a prognostic staging tool in IPM patients.

Making waves: Intelligent phage cocktail design, a pathway to precise microbial control in water systems

Current practices in water and wastewater treatment to control unwanted microbes have led to new problems, including health effects from disinfection byproducts, growth of opportunistic pathogens resistant to residual disinfectants (e.g., chlorine), and antibiotic resistance. These challenges are spurring interest in rethinking our practices of microbial control. Simultaneously, advances in molecular biology and computation power are driving renewed interest in using phages (viruses that infect bacteria) to precisely control microbial growth (aka, phage biocontrol). In this Making Waves article, I begin by reviewing the current state of research into phage cocktail design, emphasizing our limited understanding of the features of successful phage cocktails (combinations of multiple types of phages). I describe the state of modeling phage-bacteria interactions and underscore the need for increasing research efforts to predict phage cocktail success, a key gap slowing the application of phage biocontrol. I also detail how research must also focus on techniques for engineering more effective phages to offer a more rapid alternative to phage discovery from natural environments. In this way, phage cocktails comprised of phages with complementary infection strategies may be designed. The final area for increased research effort that I highlight is the need for phage cocktail design to account for possible unintended environmental effects, a risk that is increasingly acknowledged in phage ecology studies but mostly ignored by those developing phage biocontrol technologies. By focusing more research effort towards the areas necessary for intelligent phage cocktail design, we can accelerate the development of phage-based biocontrol in water systems and improve public health.

Evaluation of mrkD, pgaC and wcaJ as biomarkers for rapid identification of K. pneumoniae biofilm infections from endotracheal aspirates and bronchoalveolar lavage

Klebsiella pneumoniae has been identified as one of the most important opportunistic pathogens responsible for nosocomial infections. Antibiotic resistance and the ability to form biofilms are the two main factors involved in the persistence of infections. Conventional detection methods involve culture isolation and identification followed by biofilm assay that takes 48–72 h. Timely detection of biofilm-forming resistant pathogens is essential to appropriately treat the infection with the right dose and combinations. The present study focuses on evaluating an RT-PCR panel using mrkD, pgaC, and wcaJ genes to screen for biofilm-forming K. pneumoniae from ETA/BAL specimens. The assay accurately identified K. pneumoniae harboring samples with a limit of detection of 1 ng/µl total RNA. Representative culture-negative-PCR-positive samples were subjected to metagenomics which identified K. pneumoniae reads in these samples confirming the specificity of RT-PCR. mrkD and pgaC act as K. pneumoniae specific identification whereas wcaJ acts as a negative marker for biofilm-forming K. pneumoniae. In addition, RT-PCR results correlated well with the phenotypic biofilm-forming assay. This RT-PCR assay is the first of its kind for rapid identification of biofilm-forming K. pneumoniae. The result of this study highlights that the rapid detection of K. pneumoniae biofilms based on the RT-PCR results coupled with clinical conditions would be appropriate to treat emerging infections or to prevent re-infections in clinical settings.

Incidence and predictors of common opportunistic infections among children living with HIV at Bahir Dar City, Ethiopia

Despite the dramatic decline in the incidence of common opportunistic infections (OIs) after antiretroviral therapy initiation, they remain a significant cause of morbidity and mortality among children with HIV. For better interventions, information regarding the incidence and predictors of common OIs is essential for Children living with HIV. Still, there is a lack of studies in low and middle-income countries, including Ethiopia. Therefore, this study aims to assess the incidence and predictors of common OIs among Children living with HIV on anti-retroviral therapy (ART) at public health institutions in Bahir Dar City, Northwest Ethiopia. The reasons for excluding children not on ART is we want to study the effectiveness of chronic HIV care service, ART drugs and OIs prophylaxis drugs for the prevention of common OIs because it is obvious that the occurrence of OIs in children not on ART and OIs prophylaxis drugs is high. A health institution-based retrospective cohort study was done among 403 Human Immunodeficiency Virus-infected children at public health institutions in Bahir Dar City from 2010 to 2020. Data was entered using Epi-data version 4.6 and analyzed using STATA 14.0. A bivariable Cox-proportional hazards regression model was employed to appreciate the relationship between each explanatory variable with the outcome variable. In the bivariable analysis, variables with a p-value of less than 0.25 were candidates for the multivariable proportional hazard model. The Cox proportional hazards model was used to determine predictors of common opportunistic infections at a 5% significance level. The overall incidence rate of common opportunistic infections was 7.06 with a 95% confidence interval ((CI) 5.78, 9.75) per 100 person-years of observation. Statically significant predictors were World Health Organization (WHO) clinical stage III and IV (adjusted hazard ratio (AHR) = 1.90; (95% CI 1.34, 2.75), having fair/poor adherence to anti-retroviral therapy (ART) (AHR) = 1.80; (95% CI 1.25, 2.94) and hemoglobin level < 10 g/dl (AHR) = 2.00; (95% CI 1.36, 2.89). The overall incidence rate of common OIs among children living with HIV on ART was high. Independent predictors of common OIs among children on ART were advanced-stage of HIV disease, poor ART adherence, and lower hemoglobin level. Therefore, we recommend strongly working on the prevention of advanced stages of HIV disease and improving poor ART adherence to prevent the incidence of OIs among children living with HIV on ART.

Exploring the Probiotic Potential of Bacteroides spp. Within One Health Paradigm.

Probiotics are pivotal in maintaining or restoring the balance of human intestinal microbiota, a crucial factor in mitigating diseases and preserving the host's health. Exploration into Bacteroides spp. reveals substantial promise in their development as next-generation probiotics due to their profound interaction with host immune cells and capability to regulate the microbiome's metabolism by significantly impacting metabolite production. These beneficial bacteria exhibit potential in ameliorating various health issues such as intestinal disorders, cardiovascular diseases, behavioral disorders, and even cancer. Though it's important to note that a high percentage of them are as well opportunistic pathogens, posing risks under certain conditions. Studies highlight their role in modifying immune responses and improving health conditions by regulating lymphocytes, controlling metabolism, and preventing inflammation and cancer. The safety and efficacy of Bacteroides strains are currently under scrutiny by the European Commission for authorization in food processing, marking a significant step towards their commercialization. The recent advancements in bacterial isolation and sequencing methodologies, coupled with the integration of Metagenome-Assembled Genomes (MAGs) binning from metagenomics data, continue to unveil the potential of Bacteroides spp., aiding in the broader understanding and application of these novel probiotics in health and disease management.

The modulation of intestinal commensal bacteria possibly contributes to the growth and immunity promotion in Epinephelus akaara after feeding the antimicrobial peptide Scy-hepc.

Our previous study revealed that feeding the antimicrobial peptide (AMP) product Scy-hepc significantly enhances the growth of mariculture fish through the activation of the GH-Jak2-STAT5-IGF1 axis. However, the contribution of gut microbiota to this growth enhancement remains unclear. This study aimed to elucidate the potential mechanism involved in intestinal absorption and modulation of gut microbiota in Epinephelus akaara following Scy-hepc feeding. The results showed that a 35day regimen of Scy-hpec markedly promoted the growth of E. akaara compared to groups supplemented with either florfenicol, B. subtilis, or a vector. The growth enhancement is likely attributed to alterations in microbiota colonization in the foregut and midgut, characterized by an increasing abundance of potential probiotics (Rhizobiaceae and Lysobacter) and a decreased abundance of opportunistic pathogens (Psychrobacter and Brevundimonas) as determined by 16S rRNA analysis. Additionally, similar to the effect of florfenicol feeding, Scy-hepc significantly improved host survival rate by over 20% in response to a lethal dose challenge with Edwardsiella tarda. Further investigations demonstrated that Scy-hepc is absorbed by the fish foregut (20-40min) and midgut (20-30min) as confirmed by Western blot, ELISA, and Immunofluorescence. The absorption of Scy-hepc affected the swimming, swarming and surfing motility of Vibrio harveyi and Bacillus thuringiensis isolated from E. akaara's gut. Moreover, Scy-hepc induced the downregulation of 40 assembly genes and the upregulation expression of 5, with the most significant divergence in gene expression between opportunistic pathogens and probiotics concentrated in their motility genes (PomA/B, MotA/B). In summary, this study shows that feeding AMP Scy-hepc can promote growth and bolster immunity in E. akaara. These beneficial effects are likely due to the absorption of Scy-hepc in the fish's foregut and midgut, which modulates the colonization and motility of commensal bacteria, leading to favorable changes in the composition of the foregut and midgut microbiota. Therefore, a profound understanding of the mechanisms by which antimicrobial peptides affect host gut microbiota will contribute to a comprehensive assessment of their advantages and potential application prospects as substitutes for antibiotics in fish health and improving aquaculture practices.

Histone-like transcription factor Hfl1p in Candida albicans harmonizes nuclear and mitochondrial genomic network in regulation of energy metabolism and filamentation development

ABSTRACT Candida albicans is an opportunistic fungal pathogen known for surviving in various nutrient-limited conditions within the host and causing infections. Our prior research revealed that Hfl1p, an archaeal histone-like or Hap5-like protein, is linked to mitochondrial ATP generation and yeast-hyphae morphogenesis. However, the specific roles of Hfl1p in these virulence behaviours, through its function in the CBF/NF-Y complex or as a DNA polymerase II subunit, remain unclear. This study explores Hfl1p’s diverse functions in energy metabolism and morphogenesis. By combining proteomic analysis and phenotypic evaluations of the hfl1Δ/hfl1Δ mutant with ChIP data, we found that Hfl1p significantly impacts mitochondrial DNA-encoded CI subunits, the tricarboxylic acid (TCA) cycle, and morphogenetic pathways. This influence occurs either independently or alongside other transcription factors recognizing a conserved DNA motif (TAXXTAATTA). These findings emphasize Hfl1p’s critical role in linking carbon metabolism and mitochondrial respiration to the yeast-to-filamentous form transition, enhancing our understanding of C. albicans’ metabolic adaptability during morphological transition, an important pathogenic trait of this fungus. This could help identify therapeutic targets by disrupting the relationship between energy metabolism and cell morphology in C. albicans.

Co-infection with Mycobacterium and 20% acid-fast Nocardia in an immunocompetent patient – A case report

Nocardiosis is an opportunistic infectious disease in immunocompromised individuals, which may be fatal and in people with healthy immune systems, which is reported as a case. Mixed infections with Nocardia and Mycobacterium tuberculosis complex (MTBC) are rare. We are reporting a case of co-infection with Nocardia spp. and MTBC in an immunocompetent patient presenting with neck swelling. Interestingly, in this case, the primary identification of Nocardia was done using 20% H2SO4 as decolorizer for Ziehl–Neelsen staining. The patient was given first-line anti-tubercular treatment for the first 2 months as an intensive phase, followed by isoniazid and rifampicin for an additional 4 months, with a total of 6 months treatment, along with linezolid (600 mg twice daily for 15 days). The patient subsequently improved.

Enrichment Characteristics and Ecological Risk Prediction of Pathogens on Typical Microplastic Biofilms

As an emerging niche colonized by microorganisms, microplastics may selectively enrich pathogens, resulting in crucial ecological risks and potential threats to public health in aquatic environments. However, the enrichment characteristics and ecological risks of pathogens on different microplastic biofilms remain unclear. In this study, 16S rRNA high-throughput sequencing technology was used to investigate the differences in the bacterial community structure, occurrence characteristics of pathogens, and prediction of ecological risks on five typical microplastic biofilms of polyethylene （PE）, polypropylene （PP）, polystyrene （PS）, polyethylene terephthalate （PET）, and polyvinyl chloride （PVC） through a field in-situ incubation experiment. The results showed that after 28 d of in situ incubation, the macroscopic biofilms were formed on the surface of all microplastics, and the diversity and richness of the bacterial community on all microplastic biofilms were higher than in the surrounding water, indicating that the microorganisms in the surrounding water were selectively enriched on microplastics. Each type of microplastic biofilm had formed a unique bacterial community structure； in particular, PVC microplastics were more inclined to selectively enrich the members of Proteobacteria. A total of 47 human pathogens were identified using the HPB database, including six antibiotic resistance pathogens belonging to the lists of critical priority control. The number and total abundance of human pathogens detected on microplastic biofilm were higher than those in the surrounding water, and the dominant pathogens such as Bartonella, Burkholderia, and Brucella were selectively enriched on microplastic biofilms. Microbial phenotype prediction results based on BugBase showed that three functional phenotypes including biofilm formation, mobile element contained, and potentially pathogenic on microplastic biofilms had significantly increased by 2.38%-5.57%, 0.82%-7.13%, and 3.04%-8.30%, respectively, which were mainly contributed by α-Proteobacteria and γ-Proteobacteria. These results not only indicate that the selective enrichment of opportunistic pathogens on microplastic biofilms may lead to the increased risk of pathogenicity and antibiotic resistance co-spread but also provide reference for the accurate assessment of ecological risks caused by microplastic pollution in aquatic environments.

The Challenge of Misleading Information: Does the Interaction between Zinc and Vitamin D Influence the Immune Response against SARS-CoV-2 in the Elderly Population?

Immunization is a challenge for the elderly population and can leave this group more vulnerable to opportunistic pathogens such as SARS-CoV-2. Due to this situation, while vaccines were in the development phase, hypotheses were raised about the role of vitamins and minerals in immunization. In Brazil, there was a controversy regarding the well-known COVID-19 Kit, a standardized prescription for positive cases that contained zinc, and vitamin D, and anti-parasitic drugs. There was great controversy in scientific circles, since COVID-19 brought a major challenge for health professionals and public authorities: misleading information. In this study, we evaluated the role of vitamin D and zinc in the production of anti-SARS-CoV-2 neutralizing antibodies (NAbs) in a group of elderly residents in a nursing home in northeastern Brazil. Serum levels of COVID-19 NAbs were assessed, along with vitamin D and zinc, in two phases. The first (T1) was in August 2022 with 26 elderly people, and the second (T2) was in March 2023 with 21, due to the death of five participants. Overall, we observed satisfactory levels for vitamin D, with no participants showing a deficiency in either test, and zinc, with only two participants having a negative result at T1 and three at T2. However, a drop in the average number of NAbs was observed, especially in women (T1 = 89 ± 19 vs. T2 = 57 ± 44), highlighting the importance of monitoring this immunological parameter in the population studied. Based on the results, we suggest that there is no synergism between the micronutrients studied and NAbs (p &gt; 0.05). Further studies are needed to consolidate the findings of an absence of synergism between vitamin D and zinc in the maintenance of NAbs.

Screening and functional characterization of isocitrate lyase AceA in the biofilm formation of Vibrio alginolyticus.

Biofilm is a well-known sessile lifestyle for bacterial pathogens, but a little is known about the mechanism on biofilm formation in Vibrio alginolyticus. In this study, we screened V. alginolyticus strains with strong biofilm formation ability from coastal seawater. The antibiotic resistance of the biofilm cells (BFs) was higher than that of the planktonic cells (PTs). To study the genes and pathways involved in biofilm formation, we performed transcriptome analysis of the BFs and PTs of V. alginolyticus R9. A total of 685 differentially expressed genes (DEGs) were upregulated, and 517 DEGs were downregulated in the BFs. The upregulated DEGs were significantly enriched in several pathways including glyoxylate and dicarboxylate metabolism, while the downregulated genes were significantly enriched in the flagellar assembly pathways. The key gene involved in glyoxylate shunt, aceA, was cloned, and ΔaceA mutant was constructed to determine the function of AceA in carbon source utilization, biofilm formation, and virulence. Real-time reverse transcription PCR showed that the expression of aceA was higher at the mature stage but lower at the disperse stage of biofilm formation, and the expression of the flagellar related genes was upregulated in ΔaceA. This is the first study to illustrate the global gene expression profile during the biofilm formation of V. alginolyticus, and isocitrate lyase AceA, the key enzyme involved in glyoxylate shunt, was shown to maintain biofilms accompanied by downregulation of flagellation but promoted dispersal of BFs at the late stage.IMPORTANCEBiofilms pose serious public problems, not only protecting the cells in it from environmental hazard but also affecting the composition and abundance of bacteria, algae, fungi, and protozoa. The important opportunistic pathogen Vibrio alginolyticus is extremely ubiquitously present in seawater, and it also exhibited a strong ability to form biofilm; thus, investigation on the biofilm formation of V. alginolyticus at molecular level is fundamental for the deeper exploration of the environmental concerns arose by biofilm. In this study, transcriptome analysis of biofilm cells (BFs) and planktonic cells (PTs) from V. alginolyticus was performed and AceA was screened to play an important role in biofilm formation. AceA was shown to maintain biofilms accompanied by downregulation of flagellation but promoted dispersal of BFs at the disperse stage. This method was helpful to further understand the ability and mechanism of V. alginolyticus biofilm formation and provide clues for prevention of V. alginolyticus infection.

The novel MFS efflux pump SxtP, regulated by the LysR-type transcriptional activator SxtR, is involved in the susceptibility to sulfamethoxazole/trimethoprim (SXT) and the pathogenesis of Acinetobacter baumannii.

Acinetobacter baumannii is a notorious opportunistic pathogen responsible for healthcare-associated infections worldwide. Efflux pumps play crucial roles in mediating antimicrobial resistance, motility, and virulence. In this study, we present the identification and characterization of the new A. baumannii efflux pump SxtP belonging to the MFS superfamily (major facilitator superfamily), along with its associated activator LysR-type transcriptional regulator (LTTR) SxtR, demonstrating their roles in sulfamethoxazole/trimethoprim (also known as co-trimoxazole or SXT) resistance, surface-associated motility and virulence.

Impact of the method of delivery and feeding practice on the gut microbiome of infants in the postnatal period

BACKGROUND: The increasing frequency of cesarean sections and artificial feeding creates a predisposition to allergic diseases, obesity, and diabetes mellitus. Pathogenesis of these involves changes in the gut microbiome of infants. AIM: The aim of this study was to evaluate the impact of the method of delivery and feeding practice on the gut microbiome of infants. MATERIALS AND METHODS: This study included 103 infants aged 4-6 weeks (group 1: 39 infants born vaginally and breastfed; group 2: 10 infants born vaginally and formula-fed; group 3: 31 infants born by caesarean section and breastfed; group 4: 23 infants born by caesarean section and formula-fed), each of whom had stool collected for 16S ribosomal RNA gene sequencing. RESULTS: We found differences in the relative abundance of Akkermansia spp. [34.07 (29.29–38.85)% in group 4 and 0.01 (0.01–0.02)% in group 1; p = 0.011], Bifidobacterium spp. [30.68 (21.65–39.41)% in group 1 and 17.08 (9.86–21.68)% in group 4, (p = 0.002); 31.46 (24,30–52.97)% in group 3 and 17.08 (9.86–21.68)% in group 4 (p = 0.001)], and Enterococcus spp. [4.69 (1.01–8.59)% in group 3 and 0.58 (0.12–1.87)% in group 1 (p = 0.003); 4.29 (2.07–6.96)% in group 4 and 0.58 (0.12–1.87)% in group 1 (p = 0.001)]. The coefficient of correlation adaptometry was maximum for groups of infants who were breastfed. Analysis of the morbidity of infants in the first year of life revealed differences in the incidence of acute respiratory viral infections between infants in groups 1 and 4 (17.9 and 78.3%, respectively; p = 0.0064), as well as groups 3 and 4 (32.2 and 78.3%, respectively; p = 0.018). CONCLUSIONS: The relative abundance of Bifidobacterium spp. depends on feeding practice to a greater extent than on the method of delivery. The method of delivery affects the relative abundance of opportunistic bacteria such as Enterococcus spp. Correlation analysis demonstrated the role of breastfeeding as a mechanism for “learning” and maturing the immune system of children.

Central line-associated bloodstream infection outbreak related to Ralstonia pickettii-contaminated saline in a pediatric hematopoietic stem cell transplant center.

Ralstonia pickettii is an aerobic Gram-negative non-fermentative bacillus. It is an opportunistic pathogen that has recently prompted nosocomial outbreaks. Although it has low virulence, it can cause a wide range of invasive diseases in immunosuppressive patients. The characteristics of R. pickettii-related central line-associated bloodstream infection (CLABSI) outbreak in pediatric hematopoietic stem cell transplant (HSCT) recipients are presented in this study. This was a single-center, retrospective analysis conducted at Bahcesehir University Goztepe Medicalpark Hospital . The clinical and laboratory characteristics of twelve children with Ralstonia-related CLABSIs were analyzed. Of the twelve patients with R. pickettii growth, seven were female. The median age was 12.1 (2-17) years. Autologous HSCT was performed in two of the patients and allogeneic HSCT was performed in ten patients for both malignant and non-malignant diseases. In the conditioning regimens, all patients were given myeloablative therapy. Clinical sepsis was the most common presentation. As a result of the investigations, R. pickettii growth was observed in saline solutions. All cases were successfully treated with the appropriate antibiotic regimen and the bacteria was not found in repeat cultures. Catheter removal was required in two patients. Mortality was not observed in any patient as the outcome of the infection episode. The detection and control of the infectious source are critical in pediatric HSCT patients with severe immunosuppression, as medical equipment-related outbreaks can be life-threatening.

Localized Pneumocystis jirovecii pneumonia in a malnourished, non-HIV-infected man in the absence of any established or diagnosed immunosuppressive condition: a case report

BackgroundPneumocystis jirovecii infection is an opportunistic infection that mostly affects patients with immunosuppressive conditions like human immunodeficiency virus (HIV) infection or medications, like corticosteroids. This study reports a rare case of Pneumocystis Jiroveci infection in a relatively immunocompetent patient which presented with uncommon radiological findings.Case presentationA 46-year-old man with a malnourished appearance and a history of opium dependence presented with dry cough, dyspnea, and weight loss to the hospital. There was no evidence of an immunocompromised condition or use of any immunosuppressive medication in the history of the patient. A lung high-resolution computed tomography (HRCT) scan revealed a crazy-paving appearance and localized infiltration. Methenamine silver staining and the histopathological findings in the transbronchial lung biopsy confirmed the diagnosis of PJP. Antibiotics and bronchodilators were administrated and the patient was discharged after 6 days of hospitalization. HIV testing and immunoglobulin levels were normal in the hospital course as well as his follow-up visits. After a 2-month follow-up, the patient was in good condition despite of mild remaining infiltration in his lung.ConclusionsPJP typically affects HIV-infected patients, but due to excessive use of immunosuppressive medications, its prevalence is increasing in non-HIV-infected patients. Malnutrition may predispose the patients to PJP, even in the absence of immunosuppressive conditions.