Impaired host response and the presence of Acinetobacter baumannii in the serum microbiome of type-II diabetic patients

Acinetobacter baumannii as an oro-dental pathogen: a red alert!!

OBJECTIVES

This review highlights the existence and association of Acinetobacter baumannii with the oro-dental diseases, transforming this systemic pathogen into an oral pathogen. The review also hypothesizes possible reasons for the categorization of this pathogen as code blue due to its stealthy entry into the oral cavity.

METHODOLOGY

Study data were retrieved from various search engines reporting specifically on the association of A. baumannii in dental diseases and tray set-ups. Articles were also examined regarding obtained outcomes on A. baumannii biofilm formation, iron acquisitions, magnitude of antimicrobial resistance, and its role in the oral cancers.

RESULTS

A. baumannii is associated with the oro-dental diseases and various virulence factors attribute for the establishment and progression of oro-mucosal infections. Its presence in the oral cavity is frequent in oral microbiomes, conditions of impaired host immunity, age related illnesses, and hospitalized individuals. Many sources also contribute for its prevalence in the dental health care environment and the presence of drug resistant traits is also observed. Its association with oral cancers and oral squamous cell carcinoma is also evident.

CONCLUSIONS

The review calls for awareness on the emergence of A. baumannii in dental clinics and for the need for educational programs to monitor and control the sudden outbreaks of such virulent and resistant traits in the dental health care settings.

Short-Chain Fatty Acids and Human Health: From Metabolic Pathways to Current Therapeutic Implications

The gastrointestinal tract is home to trillions of diverse microorganisms collectively known as the gut microbiota, which play a pivotal role in breaking down undigested foods, such as dietary fibers. Through the fermentation of these food components, short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are produced, offering numerous health benefits to the host. The production and absorption of these SCFAs occur through various mechanisms within the human intestine, contingent upon the types of dietary fibers reaching the gut and the specific microorganisms engaged in fermentation. Medical literature extensively documents the supplementation of SCFAs, particularly butyrate, in the treatment of gastrointestinal, metabolic, cardiovascular, and gut-brain-related disorders. This review seeks to provide an overview of the dynamics involved in the production and absorption of acetate, propionate, and butyrate within the human gut. Additionally, it will focus on the pivotal roles these SCFAs play in promoting gastrointestinal and metabolic health, as well as their current therapeutic implications.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand the dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune, and clinical markers of microbiomes from four body sites in 86 participants over 6 years. We found that microbiome stability and individuality are body-site specific and heavily influenced by the host. The stool and oral microbiome are more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. We identify individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlate across body sites, suggesting systemic dynamics influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals show altered microbial stability and associations among microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Major alteration of Lung Microbiome and the Host Reaction in critically ill COVID-19 Patients with high viral load

Background

Patients with COVID-19 under invasive mechanical ventilation are at higher risk of developing ventilator-associated pneumonia (VAP), associated with increased healthcare costs, and unfavorable prognosis. The underlying mechanisms of this phenomenon have not been thoroughly dissected. Therefore, this study attempted to bridge this gap by performing a lung microbiota analysis and evaluating the host immune responses that could drive the development of VAP.

Materials and methods

In this prospective cohort study, mechanically ventilated patients with confirmed SARS-CoV-2 infection were enrolled. Nasal swabs (NS), endotracheal aspirates (ETA), and blood samples were collected initially within 12 hours of intubation and again at 72 hours post-intubation. Plasma samples underwent cytokine and metabolomic analyses, while NS and ETA samples were sequenced for lung microbiome examination. The cohort was categorized based on the development of VAP. Data analysis was conducted using RStudio version 4.3.1.

Results

In a study of 36 COVID-19 patients on mechanical ventilation, significant differences were found in the nasal and pulmonary microbiome, notably in Staphylococcus and Enterobacteriaceae, linked to VAP. Patients with VAP showed a higher SARS-CoV-2 viral load, elevated neutralizing antibodies, and reduced inflammatory cytokines, including IFN-δ, IL-1β, IL-12p70, IL-18, IL-6, TNF-α, and CCL4. Metabolomic analysis revealed changes in 22 metabolites in non-VAP patients and 27 in VAP patients, highlighting D-Maltose-Lactose, Histidinyl-Glycine, and various phosphatidylcholines, indicating a metabolic predisposition to VAP.

Conclusions

This study reveals a critical link between respiratory microbiome alterations and ventilator-associated pneumonia in COVID-19 patients, with elevated SARS-CoV-2 levels and metabolic changes, providing novel insights into the underlying mechanisms of VAP with potential management and prevention implications.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune and clinical markers of microbiomes from four body sites in 86 participants over six years. We found that microbiome stability and individuality are body-site-specific and heavily influenced by the host. The stool and oral microbiome were more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. Also, we identified individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlated across body sites, suggesting systemic coordination influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals showed altered microbial stability and associations between microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Study Highlights

The stability of the human microbiome varies among individuals and body sites.Highly individualized microbial genera are more stable over time.At each of the four body sites, systematic interactions between the environment, the host and bacteria can be detected.Individuals with insulin resistance have lower microbiome stability, a more diversified skin microbiome, and significantly altered host-microbiome interactions.

Exploring the pathogenesis of osteomyelitis accompanied by diabetic foot ulcers using microarray data analysis

Although numerous studies have shown distinctive similarities between osteomyelitis and diabetic foot ulcers (DFU), the common pathogenesis of both is not fully understood. The current research focuses on an in-depth study of the molecular and pathway mechanisms involved in the complication of these 2 diseases. We downloaded clinical information on osteomyelitis (GSE30119) and DFU (GSE29221) from the GEO database, along with gene expression matrices. Differentially expressed genes (DEGs) among normal individuals and patients with osteomyelitis; normal individuals and patients with DFU were identified by R software, and thus common DEGs were confirmed. We then analyzed these differential genes, including the functional pathway analysis, protein-protein interaction (PPI), modules and hub genes establishment, and transcription factor regulatory networks. We identified 109 common DEGs (46 up-regulated and 63 down-regulated genes) for subsequent analysis. The results of PPI network and the functional pathway analysis revealed the importance of immune response and inflammatory response in both diseases. Among them, chemokines and cytokines were found to be closely related to both osteomyelitis and DFU. In addition, the tumor necrosis factor (TNF) pathway and Staphylococcus aureus infection were found to have more significant roles too. The 12 most essential key genes were later screened by cytoHubba, including matrix metalloproteinases (MMP) 1, MMP3, MMP9, IL8, C-X-C chemokine receptor (CXCR) 2, C-X-C motif chemokine ligand (CXCL) 9, CXCL10, CXCL13, FCGR3B, IL1B, LCN2, S100A12. CXCL10, and MMP1 were validated using the least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) algorithms. Osteomyelitis and DFU share similar molecular and pathway mechanisms. These common key genes and pathways may provide new directions toward the future study of osteomyelitis and DFU.

Short-chain fatty acids in diseases

Short-chain fatty acids (SCFAs) are the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract. The absorption of SCFAs is mediated by substrate transporters, such as monocarboxylate transporter 1 and sodium-coupled monocarboxylate transporter 1, which promote cellular metabolism. An increasing number of studies have implicated metabolites produced by microorganisms as crucial executors of diet-based microbial influence on the host. SCFAs are important fuels for intestinal epithelial cells (IECs) and represent a major carbon flux from the diet, that is decomposed by the gut microbiota. SCFAs play a vital role in multiple molecular biological processes, such as promoting the secretion of glucagon-like peptide-1 by IECs to inhibit the elevation of blood glucose, increasing the expression of G protein-coupled receptors such as GPR41 and GPR43, and inhibiting histone deacetylases, which participate in the regulation of the proliferation, differentiation, and function of IECs. SCFAs affect intestinal motility, barrier function, and host metabolism. Furthermore, SCFAs play important regulatory roles in local, intermediate, and peripheral metabolisms. Acetate, propionate, and butyrate are the major SCFAs, they are involved in the regulation of immunity, apoptosis, inflammation, and lipid metabolism. Herein, we review the diverse functional roles of this major class of bacterial metabolites and reflect on their ability to affect intestine, metabolic, and other diseases. Video Abstract.

Prognostic Risk Factors of Carbapenem-Resistant Gram-Negative Bacteria Bloodstream Infection in Immunosuppressed Patients: A 7-Year Retrospective Cohort Study

Purpose

Carbapenem-resistant Gram-negative bacteria bloodstream infection (CRGNB-BSI) has gradually become a major threat worldwide due to its treatment difficulty and high mortality. This study aimed to determine the risk factors for CRGNB-BSI in immunosuppressed patients.

Patients and Methods

A total of 427 immunosuppressed patients with CRGNB-BSI were retrospectively investigated from 2015 to 2021. Both univariate and multivariate logistic regression analyses were applied to evaluate independent risk factors for CRGNB-BSI.

Results

The most common etiology was Klebsiella Pneumoniae (50.59%; 216/427), while the Acinetobacillus baumannii infection was associated with the highest mortality (58.25%) among all etiologies. The 60-day mortality of immunosuppressed patients with CRGNB-BSI was 52.48% (224/427). Procalcitonin (PCT) > 0.5 μg/L (OR = 2.32, 95% CI: 1.28-4.19, P = 0.005) and age > 55 years (OR = 2.06, 95% CI: 1.17-3.64, P = 0.012) were found to be predictors of 60-day mortality of CRGNB-BSI, and tigecycline regimen (OR = 3.20, 95% CI: 1.81-5.67, P < 0.001) was associated with higher mortality. Multivariate analysis also revealed that patients who developed acute kidney injury (AKI) (OR = 2.19, 95% CI: 1.11-4.30, P = 0.023), gastrointestinal bleeding (OR = 3.18, 95% CI: 1.10-9.16, P = 0.032), multiple organ dysfunction syndrome (MODS) (OR = 12.11, 95% CI: 2.61-56.19, P = 0.001), and septic shock (OR = 3.24, 95% CI: 1.77-5.94, P < 0.001) showed worse outcomes. The risk factors were also significantly associated with mortality in the different subgroups.

Conclusion

This study demonstrated that PCT > 0.5 μg/L, age > 55 years, and the tigecycline regimen were significantly associated with higher 60-day mortality among immunosuppressed patients with CRGNB- BSI. Patients developing MODS, septic shock, or AKI had worse clinical outcomes. .

Urinary tract infection in patients with diabetes mellitus and the role of parental genetics in the emergence of the disease

This study aimed to assess the role of paternal genetics in the development of diabetic mellitus (DM) and determine the impact of DM on the urinary system by investigating the percentage of patients with urinary tract infection (UTI). The study included 100 people with DM; their ages ranged from 5 to 83 years. The DM and blood sugar levels were diagnosed clinically and at a laboratory in Al-Zahra Teaching Hospital and the outpatient clinics. The age, gender, and causes of DM and the family history of diabetes were reported. Isolation and identification of bacterial species were made depending on culture media and biochemical tests. The average age of patients was 47.7±5.5, and most of them were female (67%). The incidence of DM increased with age, and the main cause of DM was likely to be a genetic predisposition (family history), where 32% of patients appeared to have a positive family history and the presence of DM in both parents or only the mother had a significant role in increasing the genetic predisposition of developing DM. Among the non-genetic causes of DM, the most common was exposure to sudden psychological or nervous shock (41%). Obesity also had an important role in the development of diabetes, and also pregnancy and smoking. Moreover, 66% of patients with type 2 DM and all with type 1 DM suffered from UTIs. The main causative agents were E. coli (60%) and Proteus spp. (13%). The majority of patients suffering from UTIs (73%) were females. In conclusion, type 2 DM is the most common, especially in females, and increases with age. The main cause of DM was family genetic predisposition and sudden shocks. The current study also showed that most diabetic patients suffered from UTIs, especially females, and the main causes of UTI inflammation are E. coli isolates.

Cigarette Smoking and Peripheral Vascular Disease are Associated with Increasing Risk of ESKAPE Pathogen Infection in Diabetic Foot Ulcers

OBJECTIVE

Diabetic foot ulcers (DFUs) and ESKAPE pathogens have attracted attention globally, but the role of ESKAPE pathogens in diabetic foot infection is not well described. The purpose of this study was to evaluate the clinical features, antimicrobial resistance, and risk factors for ESKAPE infection in patients with DFUs.

METHODS

A retrospective study was conducted on 180 patients with diabetic foot infection admitted to The Affiliated Hospital of Southwest Medical University (Luzhou, China), from January 2017 to April 2021. Antimicrobial susceptibilities of all isolates were determined. Multivariate logistic regression analysis was performed to analyze the independent risk factors for ESKAPE infection, multidrug-resistant (MDR)-ESKAPE infection, MDR-pathogen infection, and severe group in patients with DFUs.

RESULTS

A total of 206 isolates were collected, of which 42.2% were ESKAPE pathogens. The independent risk factors for ESKAPE infection were cigarette smoking (OR = 1.958; 95% CI, 1.015-3.777) and peripheral vascular disease (OR = 2.096; 95% CI, 1.100-3.992), while alcohol consumption (OR = 2.172; 95% CI, 1.104-4.272) was the independent risk factor for MDR-pathogen infection. Additionally, the independent risk factors for severe DFU group were invasive treatment (OR = 326.642; 95% CI, 76.644-1392.08), the duration of systemic antibiotic treatment (OR = 0.918; 95% CI, 0.849-0.992), and length of hospital stay (OR = 1.145; 95% CI, 1.043-1.256). No independent risk factors for MDR-ESKAPE infection were found.

CONCLUSION

Our data established the microbiological features of ESKAPE pathogens and clinical manifestations of diabetic foot infection, and provide support for monitoring and management of ESKAPE infection in patients with DFUs in southwest China.

Is the oral microbiome a source to enhance mucosal immunity against infectious diseases?

Mucosal tissues act as a barrier throughout the oral, nasopharyngeal, lung, and intestinal systems, offering first-line protection against potential pathogens. Conventionally, vaccines are applied parenterally to induce serotype-dependent humoral response but fail to drive adequate mucosal immune protection for viral infections such as influenza, HIV, and coronaviruses. Oral mucosa, however, provides a vast immune repertoire against specific microbial pathogens and yet is shaped by an ever-present microbiome community that has co-evolved with the host over thousands of years. Adjuvants targeting mucosal T-cells abundant in oral tissues can promote soluble-IgA (sIgA)-specific protection to confer increased vaccine efficacy. Th17 cells, for example, are at the center of cell-mediated immunity and evidence demonstrates that protection against heterologous pathogen serotypes is achieved with components from the oral microbiome. At the point of entry where pathogens are first encountered, typically the oral or nasal cavity, the mucosal surfaces are layered with bacterial cohabitants that continually shape the host immune profile. Constituents of the oral microbiome including their lipids, outer membrane vesicles, and specific proteins, have been found to modulate the Th17 response in the oral mucosa, playing important roles in vaccine and adjuvant designs. Currently, there are no approved adjuvants for the induction of Th17 protection, and it is critical that this research is included in the preparedness for the current and future pandemics. Here, we discuss the potential of oral commensals, and molecules derived thereof, to induce Th17 activity and provide safer and more predictable options in adjuvant engineering to prevent emerging infectious diseases.

T-Natural Killers and Interferon Gamma/Interleukin 4 in Augmentation of Infection in Foot Ulcer in Type 2 Diabetes

BACKGROUND

The link between immune system and type 2 diabetes mellitus (T2DM) pathogenesis attracted attention to demonstrate the role of immune cells and their secreted cytokines in T2DM development and its subsequent foot complications.

OBJECTIVE

To investigate the relation between T Natural killer cell (TNK) %, Interleukin 4 (IL4) and Interferon gamma (IFN-γ) and diabetic foot infection (DFI) development in patients with diabetic foot ulcer (DFU).

PATIENTS AND METHODS

Ninety patients with diabetes were included in this work, divided as T2DM group (n=30), DFU group (n=30), and DFI group (n=30). TNK% was detected using flow cytometry. Serum IL4 and IFN-γ were measured by ELISA. Diabetes biochemical parameters were also analyzed.

RESULTS

Significant decrease was detected in TNK% and IFN-γ in DFI group compared to other 2 groups (P<0.001). Significant decrease was detected in serum levels of IL4 in DFI group compared to T2DM group (P=0.006). IFN-γ/IL4 was significantly decreased in DFI compared to DFU group (P=0.020). There was a significant correlation of TNK% with both IL4 and IFN-γ (r=0.385, P<0.001; r=0.534, P<0.001, respectively). Significant negative correlation of TNK% with HbA1c and LDL was revealed (r=-0.631, P<0.001; and r=-0.261, P=0.013, respectively), while a positive correlation was seen with HDL (r=0.287, P=0.006). A significant negative correlation of IL4 with HbA1c  was found (r=-0.514, P<0.001;. As for IFN-γ, a significant negative correlation with HbA1c and LDL was detected (r=-0.369, P< 0.001; r=-0.229, P=0.030). TNK % and IFN-γ level showed negative correlations with disease duration/year (r=-0.546, P< 0.001; r=-0.338, P=0.001,respectively).

CONCLUSION

Decline in TNK frequency has essential role in T2DM pathogenesis and subsequent foot complications. Downregulation of TNK% and IFN-γ level have potential roles in predicting infection of diabetic ulcer and are correlated with disease duration.