Biostimulation with oxygen and electron donors supports micropollutant biodegradation in an experimentally simulated nitrate-reducing aquifer.

The availability of suitable electron donors and acceptors limits micropollutant natural attenuation in oligotrophic groundwater. This study investigated how electron donors with different biodegradability (humics, dextran, acetate, and ammonium), and different oxygen concentrations affect the biodegradation of 15 micropollutants (initial concentration of each micropollutant = 50 µg/L) in simulated nitrate reducing aquifers. Tests mimicking nitrate reducing field conditions showed no micropollutant biodegradation, even with electron donor amendment. However, 2,4-dichlorophenoxyacetic acid and mecoprop were biodegraded under (micro)aerobic conditions with and without electron donor addition. The highest 2,4-dichlorophenoxyacetic acid and mecoprop biodegradation rates and removal efficiencies were obtained under fully aerobic conditions with amendment of an easily biodegradable electron donor. Under microaerobic conditions, however, amendment with easily biodegradable dissolved organic carbon (DOC) inhibited micropollutant biodegradation due to competition between micropollutants and DOC for the limited oxygen available. Microbial community composition was dictated by electron acceptor availability and electron donor amendment, not by micropollutant biodegradation. Low microbial community richness and diversity led to the absence of biodegradation of the other 13 micropollutants (such as bentazon, chloridazon, and carbamazepine). Finally, adaptation and potential growth of biofilms interactively determined the location of the micropollutant removal zone relative to the point of amendment. This study provides new insight on how to stimulate in situ micropollutant biodegradation to remediate oligotrophic groundwaters as well as possible limitations of this process.

Intestinal macrophages in pathogenesis and treatment of gut leakage: current strategies and future perspectives.

Macrophages play key roles in tissue homeostasis, defense, disease, and repair. Macrophages are highly plastic and exhibit distinct functional phenotypes based on micro-environmental stimuli. In spite of several advancements in understanding macrophage biology and their different functional phenotypes in various physiological and pathological conditions, currently available treatment strategies targeting macrophages are limited. Macrophages' high plasticity and diverse functional roles-including tissue injury and wound healing mechanisms-mark them as potential targets to mine for efficient therapeutics to treat diseases. Despite mounting evidence on association of gut leakage with several extraintestinal diseases, there is no targeted standard therapy to treat gut leakage. Therefore, there is an urgent need to develop therapeutic strategies to treat this condition. Macrophages are the cells that play the largest role in interacting with the gut microbiota in the intestinal compartment and exert their intended functions in injury and repair mechanisms. In this review, we have summarized the current knowledge on the origins and phenotypes of macrophages. The specific role of macrophages in intestinal barrier function, their role in tissue repair mechanisms, and their association with gut microbiota are discussed. In addition, currently available therapies and the putative tissue repair mediators of macrophages for treating microbiota dysbiosis induced gut leakage are also discussed. The overall aim of this review is to convey the intense need to screen for microbiota induced macrophage-released prorepair mediators, which could lead to the identification of potential candidates that could be developed for treating the leaky gut and associated diseases.

Interaction between mitochondria and microbiota modulating cellular metabolism in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a prototypic complex disease in the gastrointestinal tract that has been increasing in incidence and prevalence in recent decades. Although the precise pathophysiology of IBD remains to be elucidated, a large body of evidence suggests the critical roles of mitochondria and intestinal microbiota in the pathogenesis of IBD. In addition to their contributions to the disease, both mitochondria and gut microbes may interact with each other and modulate disease-causing cell activities. Therefore, we hypothesize that dissecting this unique interaction may help to identify novel pathways involved in IBD, which will further contribute to discovering new therapeutic approaches to the disease. As poorly treated IBD significantly affects the quality of life of patients and is associated with risks and complications, successful treatment is crucial. In this review, we stratify previously reported experimental and clinical observations of the role of mitochondria and intestinal microbiota in IBD. Additionally, we review the intercommunication between mitochondria, and the intestinal microbiome in patients with IBD is reviewed along with the potential mediators for these interactions. We specifically focus on their roles in cellular metabolism in intestinal epithelial cells and immune cells. To this end, we propose a potential therapeutic intervention strategy for IBD.

Antibacterial and Antibiofilm Efficacy of Copper-Doped Phosphate Glass on Pathogenic Bacteria.

This study aimed to investigate the antibacterial [minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC)] and antibiofilm activity [log10 colony forming unit/mL (CFU/mL) and biofilm disruption] of copper-doped phosphate glass (CDPG) against Streptococcus oralis, Enterococcus faecalis, Lactobacillus casei, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. METHODS: the antibacterial activity was determined using microbroth dilution and time-kill assay. The antibiofilm activity was investigated using crystal violet and confocal laser scanning microscopy. Bacteria growing in absence of CDPG were used as controls. RESULTS: the MIC was ≥125 mg of CPDG/mL; the log10 CFU/mL reduction ranged from 2.66-3.14 to 6.23-9.65 after 4 and 24 h respectively. Generally, no growth was observed after 24 h of treatment with CDPG; the MBC was 250 mg/mL for L. casei and S. oralis while 500 mg/mL for the rest of the bacteria. The highest and lowest antibiofilm activity was observed against S. oralis and E. coli respectively. Three patterns of complete biofilm disruption were seen: (i) large areas with E. fecalis and S. oralis, (ii) medium-size pockets with S. aureus and P. aeruginosa, or (iii) small areas with E. coli and L. casei. CONCLUSION: CDPG can be potentially used as an antibacterial and an antibiofilm agent against oral biofilm-forming bacteria.

Whole genome sequence analysis of NDM-1, CMY-4, and SHV-12 coproducing Salmonella enterica serovar Typhimurium isolated from a case of fatal burn wound infection.

Salmonella species are frequently associated with gastrointestinal infections such as diarrhea. However, extraintestinal Salmonella infections, including burn infections, have been described. Here, we report the first case of a carbapenem-resistant and metallo-ß-lactamase (New Delhi metallo-ß-lactamase), extended-spectrum ß-lactamase (SHV-12), and AmpC ß-lactamase (CMY-4) coproducing Salmonella Typhimurium isolated from a fatal case of burn wound infection. The publication highlights the necessity for the rational use of antibiotics (particularly the rational use of last-resort antibiotics such as carbapenems) in hospitals and burn units, as well as the need for systematic screening of Salmonella spp. (including Salmonella enterica serovar Typhimurium) for resistance to carbapenem antibiotics.

Epidemiology of diabetic foot infections in a reference tertiary hospital in India

Abstract Introduction The present study attempts to examine the microbial profile and antibiotic susceptibility of diabetic foot infections in the intensive care unit of a tertiary referral centre for diabetic foot. As part of the study, we also attempted to find the prevalence of blaNDM-like gene among carbapenem-resistant gram negative infections. Methodology A prospective study of 261 patients with diabetic foot infections was performed during the period between January 2014 and June 2014. Results A total of 289 isolates were obtained from 178 tissue samples from 261 patients, 156 (59.7%) males and 105 (40.2%) females, with a mean age of 58 years (-15 years), having diabetic foot infection. No growth was seen in thirty eight (17.6%) tissue samples. Out of the total samples, 44.3% were monomicrobial and 55.7% were polymicrobial. Gram negative pathogens were predominant (58.5%). Seven of the total isolates were fungal; 0.7% showed pure fungal growth and 1.7% were mixed, grown along with some bacteria. The most frequently isolated bacteria were Staphylococcus aureus (26.9%), followed by Pseudomonas aeruginosa (20.9%). Of the 58.5% gram negative pathogens, 16.5% were Enterobacteriaceae resistant to carbapenems. Among these isolates, 4 (25%) were positive for blaNDM-like gene. Among the rest, 18.6% were carbapenem-resistant Pseudomonas, among which 4 (36.3%) were blaNDM. Among the Staphylococci, 23.7% were methicillin-resistant Staphylococcus aureus. Conclusions Our results support the recent view that gram negative organisms, depending on the geographical location, may be predominant in DFIs. There is an increase in multidrug-resistant pathogens, especially carbapenem resistance and this is creeping rapidly. We need to be more judicious while using empiric antibiotics.

Epidemiology of diabetic foot infections in a reference tertiary hospital in India.

INTRODUCTION: The present study attempts to examine the microbial profile and antibiotic susceptibility of diabetic foot infections in the intensive care unit of a tertiary referral centre for diabetic foot. As part of the study, we also attempted to find the prevalence of blaNDM-like gene among carbapenem-resistant gram negative infections. METHODOLOGY: A prospective study of 261 patients with diabetic foot infections was performed during the period between January 2014 and June 2014. RESULTS: A total of 289 isolates were obtained from 178 tissue samples from 261 patients, 156 (59.7%) males and 105 (40.2%) females, with a mean age of 58 years (-15 years), having diabetic foot infection. No growth was seen in thirty eight (17.6%) tissue samples. Out of the total samples, 44.3% were monomicrobial and 55.7% were polymicrobial. Gram negative pathogens were predominant (58.5%). Seven of the total isolates were fungal; 0.7% showed pure fungal growth and 1.7% were mixed, grown along with some bacteria. The most frequently isolated bacteria were Staphylococcus aureus (26.9%), followed by Pseudomonas aeruginosa (20.9%). Of the 58.5% gram negative pathogens, 16.5% were Enterobacteriaceae resistant to carbapenems. Among these isolates, 4 (25%) were positive for blaNDM-like gene. Among the rest, 18.6% were carbapenem-resistant Pseudomonas, among which 4 (36.3%) were blaNDM. Among the Staphylococci, 23.7% were methicillin-resistant Staphylococcus aureus. CONCLUSIONS: Our results support the recent view that gram negative organisms, depending on the geographical location, may be predominant in DFIs. There is an increase in multidrug-resistant pathogens, especially carbapenem resistance and this is creeping rapidly. We need to be more judicious while using empiric antibiotics.