Different Dynamic Patterns of β-Lactams, Quinolones, Glycopeptides and Macrolides on Mouse Gut Microbial Diversity

A new approach: preventive protocols with yeast products and essential oils can reduce the in-feed use of antibiotics in growing-finishing pigs

The objective of this study was to evaluate the effects of yeast products (YP) and essential oils (EO) in total or partial replacement to in-feed antibiotic protocols (growth promoter and prophylactic), both in recommended doses and in overdose of prophylactic antibiotics (PA), on growth performance, and diarrhea incidence in the growing-finishing pigs; and fecal microbiota in market hogs. Four hundred pigs (20.36 ± 2.64 kg) were assigned to five treatments in a randomized block design: diets with prophylactic and growth promoter antibiotics (ANT); ANT with 30% more PA (ANT+30); diets with less PA and YP (ANT+Y); diets with less PA, YP and EO (ANT+Y+EO); and antibiotics-free diets with YP and EO (Y+EO). The content of the active components of the YP was 60% purified β-1,3/1,6-glucans extracted from Saccharomyces cerevisiae yeast (Macrogard), 20% functional water-soluble MOS (HyperGen), and 18% MOS, extracted from Saccharomyces cerevisiae yeast (ActiveMOS). From 0 to 14 d, pigs of the ANT+30, ANT+Y, and ANT+Y+EO treatments showed a greater body weight (BW) and average daily gain (ADG) compared to pigs from the Y+EO group. From 14 to 35 d, pigs of ANT+30 and ANT+Y+EO treatments were heavier than Y+EO group. At 105 d, ANT pigs had a higher BW than the Y+EO group. For the entire period, ADG of ANT pigs was greater, and feed conversion ratio better than Y+EO pigs. From 0 to 35 d, pigs of the Y+EO treatment showed a higher diarrhea incidence compared to pigs of the other groups. From 49 to 70 d, ANT+Y and ANT+Y+EO treatments showed a lower diarrhea incidence than Y+EO group, which remained the case during the overall period. At 105 d, the alpha diversity of fecal microbiota by Shannon Entropy was lower in ANT, ANT+30, and Y+EO groups than observed for ANT+Y+EO group. The abundance of Firmicutes phylum and Firmicutes/Bacteroidetes ratio was higher in ANT than in ANT+Y+EO pigs. Proteobacteria phylum abundance in ANT+Y+EO was higher than ANT, ANT+Y, and Y+EO. Peptostreptococcaceae family abundance was higher in ANT, ANT+30, and ANT+Y groups than in ANT+Y+EO and Y+EO groups. ANT+Y+EO and Y+EO groups show a lower abundance of SMB53 genus than ANT and ANT+30 groups. In conclusion, the use of YP and EO, in partial replacement to the in-feed antibiotic protocols, does not reduce the growth performance, can replace antibiotic growth promotors, and reduce the in-feed use of PA in growing-finishing pigs. The use of YP and EO, together with PA, increases the microbial diversity, despite having important genera for weight gain in less abundance. Overdose of PA does not improve growth performance and reduces microbial diversity, which does not characterize it as an efficient preventive protocol.

Determination of Risk Factors for Infectious Diarrhea in Patients with Hematological Malignancy

BACKGROUND

This study aimed to determine the risk factors of infectious diarrhea in patients undergoing chemotherapy or hematopoietic stem cell transplantation for hematological malignancies.

MATERIALS AND METHODS

This was a prospective, observational study. Patients in whom the infectious agent was determined by laboratory examination were considered to have infectious diarrhea. Patients with diarrhea were categorized as infectious or unidentified and compared in terms of demographic data, treatments, risk factors, laboratory findings, and prognosis.

RESULTS

A total of 838 patients were hospitalized, among which 105 patients who met the inclusion criteria were included (12.5%). The patients were divided into two groups: 67 (63.8%) with unidentified diarrhea and 38 (36.2%) with infectious diarrhea. There were no differences between these groups in terms of age, sex, types of hematological malignancies, and presence of comorbidities. The most commonly isolated microorganism was Clostridioides difficile (12.4%). The rate of corticosteroid use was higher in the group with infectious diarrhea (39.5%) than in the group with unidentified diarrhea (7.5%) (P <0.001). The rate of granulocyte colony-stimulating factor (GCSF) use was higher in patients with unidentified diarrhea than in patients with infectious diarrhea (67.2% vs. 42.1%, P=0.022). The median duration of diarrhea was 9 (4-10) days in the group with infectious diarrhea and 5 (3-8) days in the group with unidentified diarrhea (P=0.012). According to the multivariate logistic regression model, corticosteroid treatment increased the risk of infectious diarrhea by a 4.75-fold (95% confidence interval [CI], 1.32-17.02) times. Moreover, the duration of diarrhea may result in a 1.15 (95% CI, 1.02-1.31) fold increase in the risk of infectious diarrhea, while GCSF treatment had a 2.84 (1/0.35) (95% CI, 0.12-0.96) fold risk-reducing effect against infectious diarrhea.

CONCLUSION

Infectious diarrhea lasts longer than unidentified diarrhea in patients with hematological malignancies. Although corticosteroid use is a risk factor for developing infectious diarrhea, GCSF use has a protective effect.

Urinary antibiotic levels and risk of overweight/obesity in preschool children: A biomonitoring-based study from eastern China

There is limited evidence linking antibiotic exposure, particularly from contaminated food or drinking water, to childhood obesity. The study aimed to investigate the association between urinary antibiotic levels and overweight/obesity in preschool children. In the case-control study, 121 overweight/obese preschoolers and 242 controls (aged 3-6 years) from eastern China were enrolled in 2022 based on age, sex, and study site matching. Overweight/obesity was determined using body mass index (BMI) and weight for height (WFH) criteria derived from national data. A total of 50 antibiotics from 8 categories were analyzed using ultra-performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS). We identified major dietary patterns using principal component analysis (PCA) and examined the associations of antibiotic exposure with childhood overweight/obesity using multivariate logistic regression. Twenty-four individual antibiotics were detected in more than 10 % of the samples, and overall detection rates were up to 100 %. Overweight/obese children had a higher exposure to veterinary antibiotics (VAs) than normal weight children. PCA analysis showed that children who were overweight/obese had higher scores of "Aquatic products preferred dietary pattern" and "Cereals preferred dietary pattern" compared to children with normal weight. Multivariate logistic regression analyses indicated that exposure to elevated levels of deoxytetracycline (OR: 1.72; 95 %CI: 1.00-2.93) and quinolones (OR: 1.63; 95 %CI: 1.04-2.57) was significantly related to an increased risk of BMI-based overweight/obesity. Quinolones exposure was also significantly associated with WFH-based overweight/obesity, primarily in boys. After adjustment for all covariates, higher exposure to ofloxacin (of the quinolones) was significantly related to overweight/obesity in girls. Exposure to certain antibiotics, especially quinolones, may increase the risk of overweight/obesity in preschoolers. More prospective, well-designed studies are needed to clarify these findings.

Circulating T cell profiles associate with enterotype signatures underlying hematological malignancy relapses

Early administration of azithromycin after allogeneic hematopoietic stem cell transplantation was shown to increase the relapse of hematological malignancies. To determine the impact of azithromycin on the post-transplant gut ecosystem and its influence on relapse, we characterized overtime gut bacteriome, virome, and metabolome of 55 patients treated with azithromycin or a placebo. We describe four enterotypes and the network of associated bacteriophage species and metabolic pathways. One enterotype associates with sustained remission. One taxon from Bacteroides specifically associates with relapse, while two from Bacteroides and Prevotella correlate with complete remission. These taxa are associated with lipid, pentose, and branched-chain amino acid metabolic pathways and several bacteriophage species. Enterotypes and taxa associate with exhausted T cells and the functional status of circulating immune cells. These results illustrate how an antibiotic influences a complex network of gut bacteria, viruses, and metabolites and may promote cancer relapse through modifications of immune cells.

Dietary 5-demethylnobiletin prevents antibiotic-associated dysbiosis of gut microbiota and damage to the colonic barrier

5-Demethylnobiletin (5DN) is an important ingredient of citrus extract that is rich in polymethoxyflavones (PMFs). In this study, we systemically investigated the preventive effects of 5DN on antibiotic-associated intestinal disturbances. Experimental mice were gavaged 0.2 mL per day of the antibiotic cocktail (12.5 g L^-1 cefuroxime and 10 g L^-1 levofloxacin) for 10 days, accompanied by dietary 0.05% 5DN for 10 and 20 days. The results showed that the combination of cefuroxime and levofloxacin caused swelling of the cecum and injury to the colon tissue. Meanwhile, the balance of intestinal oxidative stress and the barrier function of mice was also damaged by the antibiotics through upregulation of the relative mRNA levels of superoxide dismutase 3 (SOD3), quinine oxidoreductase 1 (NQO1) and glutathione peroxidase 1 (GPX1), and downregulation of the relative protein levels of tight junction proteins (TJs). Moreover, antibiotic exposure led to disorder of the gut microbiota, particularly increased harmful bacteria (Proteobacteria) and decreased beneficial bacteria (Bacteroideta). However, dietary 5DN could reduce antibiotic-associated intestinal damage, evidenced by the results that 5DN alleviated gut oxidative damage and attenuated intestinal barrier injury via increasing the expression of TJs including occludin and zonula occluden1 (ZO1). Additionally, dietary 5DN modulated the composition of the gut microbiota in antibiotic-treated mice by increasing the relative levels of beneficial bacteria, such as Dubosiella and Lactobacillus. Moreover, PMFs increased the contents of isobutyric acid and butyric acid, which were almost eliminated by antibiotic exposure. In conclusion, 5DN could alleviate antibiotic-related imbalance of intestinal oxidative stress, barrier function damage, intestinal flora disorders and the reduction of short-chain fatty acids (SCFAs), which lays a foundation for exploring safer and more effective ways to prevent or mitigate antibiotic-associated intestinal damage.

Microbiome Structure and Mucosal Morphology of Jejunum Appendix and Colon of Rats in Health and Dysbiosis

Gut microbiota contributes to human health. Plenty of studies demonstrate that antibiotics can disrupt gut ecosystem leading to dysbiosis. Little is known about the microbial variation of appendix and its up/downstream intestine after antibiotic treatment. This study aimed to investigate the microbiome and mucosal morphology of jejunum, appendix, and colon of rats in health and dysbiosis. A rodent model of antibiotic-induced dysbiosis was employed. Microscopy was used to observe mucosal morphological changes. 16S rRNA sequencing was performed for identifying bacterial taxa and microbiome structure. The appendices of dysbiosis were found enlarged and inflated with loose contents. Microscopy revealed the impairment of intestinal epithelial cells. High-throughput sequencing showed the Operational Taxonomic Units changed from 361 ± 33, 634 ± 18, 639 ± 19 in the normal jejunum, appendix, colon to 748 ± 98, 230 ± 11, 253 ± 16 in the disordered segments, respectively. In dysbiosis, Bacteroidetes translocated inversely from the colon and appendix (0.26%, 0.23%) to the jejunum (13.87% ± 0.11%); the relative abundance of all intestinal Enterococcaceae increased, while Lactobacillaceae decreased. Several bacterial clusters were found correlated to the normal appendix, whereas nonspecific clusters correlated to the disordered appendix. In conclusion, species richness and evenness reduced in the disordered appendix and colon; similar microbiome patterns were shared between the appendix and colon regardless of dysbiosis; site-specific bacteria were missing in the disordered appendix. Appendix is likely a transit region involving in upper and lower intestinal microflora modulation. The limitation of this study is all the data were derived from rats. We must be cautious about translating the microbiome results from rats to humans.

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Evaluation of an Antibiotic Cocktail for Fecal Microbiota Transplantation in Mouse

Objective

This study aimed to evaluate the effect of an antibiotic cocktail on gut microbiota and provide a reference for establishing an available mouse model for fecal microbiota transplantation (FMT) of specific microbes.

Design

C57BL/6J mice (n = 24) had free access to an antibiotic cocktail containing vancomycin (0.5 g/L), ampicillin (1 g/L), neomycin (1 g/L), and metronidazole (1 g/L) in drinking water for 3 weeks. Fecal microbiota was characterized by 16S rDNA gene sequencing at the beginning, 1st week, and 3rd week, respectively. The mice were then treated with fecal microbiota from normal mice for 1 week to verify the efficiency of FMT.

Results

The diversity of microbiota including chao1, observed species, phylogenetic diversity (PD) whole tree, and Shannon index were decreased significantly (P < 0.05) after being treated with the antibiotic cocktail for 1 or 3 weeks. The relative abundance of Bacteroidetes, Actinobacteria, and Verrucomicrobia was decreased by 99.94, 92.09, and 100%, respectively, while Firmicutes dominated the microbiota at the phylum level after 3 weeks of treatment. Meanwhile, Lactococcus, a genus belonging to the phylum of Firmicutes dominated the microbiota at the genus level with a relative abundance of 80.63%. Further FMT experiment indicated that the fecal microbiota from the receptor mice had a similar composition to the donor mice after 1 week.

Conclusion

The antibiotic cocktail containing vancomycin, ampicillin, neomycin, and metronidazole eliminates microbes belonging to Bacteroidetes, Actinobacteria, and Verrucomicrobia, which can be recovered by FMT in mice.

SARS-CoV-2 and Prevotella spp.: friend or foe? A systematic literature review

During this global pandemic of the COVID-19 disease, a lot of information has arisen in the media and online without scientific validation, and among these is the possibility that this disease could be aggravated by a secondary bacterial infection such as Prevotella, as well as the interest or not in using azithromycin, a potentially active antimicrobial agent. The aim of this study was to carry out a systematic literature review, to prove or disprove these allegations by scientific arguments. The search included Medline, PubMed, and Pubtator Central databases for English-language articles published 1999-2021. After removing duplicates, a total of final eligible studies (n=149) were selected. There were more articles showing an increase of Prevotella abundance in the presence of viral infection like that related to Human Immunodeficiency Virus (HIV), Papillomavirus (HPV), Herpesviridae and respiratory virus, highlighting differences according to methodologies and patient groups. The arguments for or against the use of azithromycin are stated in light of the results of the literature, showing the role of intercurrent factors, such as age, drug consumption, the presence of cancer or periodontal diseases. However, clinical trials are lacking to prove the direct link between the presence of Prevotella spp. and a worsening of COVID-19, mainly those using azithromycin alone in this indication.

Microbiomics Revealed the Disturbance of Intestinal Balance in Rabbits with Diarrhea Caused by Stopping the Use of an Antibiotic Diet

The harmful effects of diarrhea on the growth performance of rabbits have been well documented, but the details of the potential mechanism of intestinal diarrhea when antibiotics are stopped are still unclear. Here, PacBio sequencing technology was used to sequence the full length 16S rRNA gene of the microbiota of intestinal content samples, in order to characterize the bacterial communities in the small intestine (duodenum and jejunum) and large intestine (colon and cecum) in normal Hyplus rabbits and those with diarrhea. The histopathological examination showed that intestinal necrosis occurred in different degrees in the diarrhea group, and that the mucosal epithelium was shed and necrotic, forming erosion, and the clinical manifestation was necrosis. However, the intestinal tissue structure of the normal group was normal. The results revealed that there were significant differences in bacterial communities and structure between the diarrhea and normal groups of four intestinal segments (p < 0.05). In general, 16 bacterial phyla, 144 bacterial genera and 22 metabolic pathways were identified in the two groups. Tax4Fun functional prediction analysis showed that KEGG related to amino acid metabolism and energy metabolism was enriched in the large intestines of rabbits with diarrhea, whereas lipid metabolism was more abundant in the small intestine of rabbits with diarrhea. In conclusion, the change in the relative abundance of the identified dominant microbiota, which could deplete key anti-inflammatory metabolites and lead to bacterial imbalance and diarrhea, resulted in diarrhea in Hyplus rabbits that stopped using antibiotics.

Antimicrobial therapy during cancer treatment: Beyond antibacterial effects

Cancer treatment options have evolved to include immunotherapy and targeted therapy, in addition to traditional chemoradiation. Chemoradiation places the patient at a higher risk of infection through a myelosuppressive effect. High clinical suspicion and early use of antimicrobials play a major role in decreasing any associated morbidity and mortality. This has led to a widespread use of antimicrobials in cancer patients. Antimicrobial use, however, does not come without its perils. Dysbiosis caused by antimicrobial use affects responses to chemotherapeutic agents and is prognostic in the development and severity of certain cancer treatment-related complications such as graft-versus-host disease and Clostridioides difficile infections. Studies have also demonstrated that an intact gut microbiota is essential in the anticancer immune response. Antimicrobial use can therefore modulate responses and outcomes with immunotherapy targeting immune checkpoints. In this review, we highlight the perils associated with antimicrobial use during cancer therapy and the importance of a more judicious approach. We discuss the nature of the pathologic changes in the gut microbiota resulting from antimicrobial use. We explore the effect these changes have on responses and outcomes to different cancer treatment modalities including chemotherapy and immunotherapy, as well as potential adverse clinical consequences in the setting of stem cell transplant.

Comparison of antibiotic-associated diarrhea caused by cefoperazone/sulbactam or piperacillin/tazobactam in neurosurgery patients

Objective

To compare the occurrence and prognosis of antibiotic-associated diarrhea (AAD) between patients treated with cefoperazone/sulbactam and piperacillin/tazobactam in the neurosurgery department.

Methods

This study retrospectively analyzed patients who received cefoperazone/sulbactam or piperacillin/tazobactam to prevent or treat hospital-acquired infections in the Department of Neurosurgery of The First Medical Center of Chinese PLA General Hospital between October 2019 and October 2020. For patients with AAD, clinical data, antibiotic usage, the incidence of diarrhea, treatment, and prognosis were collected and analyzed.

Results

In total, 356 patients were enrolled, and 65 (18.6%) experienced AAD, 38 patients in the cefoperazone/sulbactam group and 27 patients in the piperacillin/tazobactam group. The AAD rate did not differ between the treatment arms. Conversely, the dosage, intensity, and duration of antibiotic therapy differed between the groups, whereas no differences were noted in the time to the appearance of diarrhea and prognosis. According to regression analysis, the incidence of AAD did not differ between the groups (odds ratio [OR] = 0.85, 95% confidence interval [CI] = 0.46–1.48).

Conclusion

Cefoperazone/sulbactam or piperacillin/tazobactam can lead to a similar incidence rate of AAD. The combined application of antibiotics and empiric therapy often occurs. The rational use of antibiotics should be improved.

Effects of Tea against Alcoholic Fatty Liver Disease by Modulating Gut Microbiota in Chronic Alcohol-Exposed Mice

Gut microbiota dysbiosis has been a crucial contributor to the pathogenesis of alcoholic fatty liver disease (AFLD). Tea is a popular beverage worldwide and exerts antioxidant and anti-inflammatory activities, as well as hepatoprotective effects. However, the potential role of gut microbiota regulated by tea in the prevention and management of AFLD remains unclear. Here, the protective effects of oolong tea, black tea, and dark tea on AFLD and its regulation of gut microbiota in chronic alcohol-exposed mice were explored and investigated. The results revealed that tea supplementation significantly prevented liver steatosis, decreased oxidative stress and inflammation, and modulated gut microbiota in chronic alcohol-exposed mice, especially oolong tea and dark tea. However, black tea showed less effectiveness against liver injury caused by alcohol. Moreover, the diversity, structure and composition of chronic alcohol-disrupted gut microbiota were restored by the supplementation of oolong tea and dark tea based on the analysis of gut microbiota. Furthermore, the relationship between liver injury biochemical indicators and gut microbiota indicated that some specific bacteria, such as Bacteroides, Alloprevotella, and Parabacteroides were closely associated with AFLD. In addition, the phytochemical components in tea extracts were measured by high-performance liquid chromatography, which could contribute to preventive effects on AFLD. In summary, oolong tea and dark tea could prevent chronic alcohol exposure-induced AFLD by modulating gut microbiota.

Antimicrobial Prophylaxis and Modifications of the Gut Microbiota in Children with Cancer

In children with cancer, chemotherapy can produce cytotoxic effects, resulting in immunosuppression and an augmented risk of febrile neutropenia and bloodstream infections. This has led to widespread use of antibiotic prophylaxis which, combined with intensive chemotherapy treatment, could have a long-term effect on the gastrointestinal microbiome. In this review, we aimed to analyze the current literature about the widespread use of antibiotic prophylaxis in children experiencing infectious complications induced by chemotherapy and its effects on the gut microbiome. Our review of the literature shows that antimicrobial prophylaxis in children with cancer is still a trending topic and, at the moment, there are not enough data to define universal guidelines. Children with cancer experience long and painful medical treatments and side effects, which are associated with great economic and social burdens, important psychological consequences, and dysbiosis induced by antibiotics and also by chemotherapy. Considering the importance of a healthy gut microbiota, studies are needed to understand the impact of dysbiosis in response to therapy in these children and to define how to modulate the microbiome to favor a positive therapeutic outcome.

Antibiotic-induced gut dysbiosis and barrier disruption and the potential protective strategies

The oral antibiotic therapies administered widely to people and animals can cause gut dysbiosis and barrier disruption inevitably. Increasing attention has been directed toward antibiotic-induced gut dysbiosis, which involves a loss of diversity, changes in the abundances of certain taxa and consequent effects on their metabolic capacity, and the spread of antibiotic-resistant bacterial strains. Treatment with beta-lactam, glycopeptide, and macrolide antibiotics is associated with the depletion of beneficial commensal bacteria in the genera Bifidobacterium and Lactobacillus. The gut microbiota is a reservoir for antibiotic resistance genes, the prevalence of which increases sharply after antibiotic ingestion. The intestinal barrier, which comprises secretory, physical, and immunological barriers, is also a target of antibiotics. Antibiotic induced changes in the gut microbiota composition could induce weakening of the gut barrier through changes in mucin, cytokine, and antimicrobial peptide production by intestinal epithelial cells. Reports have indicated that dietary interventions involving prebiotics, probiotics, omega-3 fatty acids, and butyrate supplementation, as well as fecal microbiota transplantation, can alleviate antibiotic-induced gut dysbiosis and barrier injuries. This review summarizes the characteristics of antibiotic-associated gut dysbiosis and barrier disruption, as well as the strategies for alleviating this condition. This information is intended to provide a foundation for the exploration of safer, more efficient, and affordable strategies to prevent or relieve antibiotic-induced gut injuries.

Phages versus Antibiotics To Treat Infected Diabetic Wounds in a Mouse Model: a Microbiological and Microbiotic Evaluation

The management of diabetic foot infections is frequently a dead end for surgeons and infectious disease specialists. When the pathogen to be treated is not resistant to conventional antibiotics, the latter tend to unbalance the intestinal microbiota, which is linked to multiple pathologies. A local treatment with bacteriophages, in addition to being as much or even more effective than antibiotics from a clinical and microbiological point of view, makes it possible to respect the patient’s microbiota. These results suggest that the use of this therapeutic alternative is a major avenue and that the introduction of recommendations for their use is now necessary.

Diabetes is marked by a range of complications, including chronic infections that can lead to limb amputation. The treatment of infected wounds is disrupted by arteriopathies that reduce tissue perfusion as well as by the critical development of bacterial resistance. We evaluated the impact of a local application of bacteriophages compared to that of a per os administration of amoxicillin-clavulanic acid in a mouse model of Staphylococcus aureus wound infection. We found that phage treatment resulted in improved clinical healing and a reduction in local bacterial load at 7 and 14 days postinfection. Unlike antibiotics, phage therapy did not deplete the intestinal microbiota of treated animals. Amoxicillin resulted in a reduction of alpha and beta diversities of the murine microbiota and disturbed architecture even 7 days after the end of treatment, whereas phage treatment did not impinge on the microbiota.

IMPORTANCE The management of diabetic foot infections is frequently a dead end for surgeons and infectious disease specialists. When the pathogen to be treated is not resistant to conventional antibiotics, the latter tend to unbalance the intestinal microbiota, which is linked to multiple pathologies. A local treatment with bacteriophages, in addition to being as much or even more effective than antibiotics from a clinical and microbiological point of view, makes it possible to respect the patient’s microbiota. These results suggest that the use of this therapeutic alternative is a major avenue and that the introduction of recommendations for their use is now necessary.

Clarithromycin expands CD11b+Gr-1+ cells via the STAT3/Bv8 axis to ameliorate lethal endotoxic shock and post-influenza bacterial pneumonia

Macrolides are used to treat various inflammatory diseases owing to their immunomodulatory properties; however, little is known about their precise mechanism of action. In this study, we investigated the functional significance of the expansion of myeloid-derived suppressor cell (MDSC)-like CD11b⁺Gr-1⁺ cells in response to the macrolide antibiotic clarithromycin (CAM) in mouse models of shock and post-influenza pneumococcal pneumonia as well as in humans. Intraperitoneal administration of CAM markedly expanded splenic and lung CD11b⁺Gr-1⁺ cell populations in naïve mice. Notably, CAM pretreatment enhanced survival in a mouse model of lipopolysaccharide (LPS)-induced shock. In addition, adoptive transfer of CAM-treated CD11b⁺Gr-1⁺ cells protected mice against LPS-induced lethality via increased IL-10 expression. CAM also improved survival in post-influenza, CAM-resistant pneumococcal pneumonia, with improved lung pathology as well as decreased interferon (IFN)-γ and increased IL-10 levels. Adoptive transfer of CAM-treated CD11b⁺Gr-1⁺ cells protected mice from post-influenza pneumococcal pneumonia. Further analysis revealed that the CAM-induced CD11b⁺Gr-1⁺ cell expansion was dependent on STAT3-mediated Bv8 production and may be facilitated by the presence of gut commensal microbiota. Lastly, an analysis of peripheral blood obtained from healthy volunteers following oral CAM administration showed a trend toward the expansion of human MDSC-like cells (Lineage⁻HLA-DR⁻CD11b⁺CD33⁺) with increased arginase 1 mRNA expression. Thus, CAM promoted the expansion of a unique population of immunosuppressive CD11b⁺Gr-1⁺ cells essential for the immunomodulatory properties of macrolides.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of anti-inflammatory myeloid progenitors that expand in response to acute and chronic inflammation as well as in various diseases, such as autoimmune diseases and cancer. The macrolide antibiotic clarithromycin has immunomodulatory effects in various inflammatory diseases, distinct from its antimicrobial effects, but the mechanism underlying these effects is unknown. The present study demonstrates that clarithromycin treatment induces a marked expansion of CD11b⁺Gr-1⁺ MDSC-like cells in the spleen and lungs, sufficient to protect mice from LPS-induced lethality and clarithromycin-resistant bacterial pneumonia via increased IL-10 and decreased IFN-γ levels. Clarithromycin-induced CD11b⁺Gr-1⁺ cell expansion was dependent on STAT3-mediated Bv8 production. Moreover, expansion of the immunosuppressive MDSC-like cell population was observed following clarithromycin treatment in humans. Collectively, these results suggest that the immunomodulatory effects of clarithromycin can be attributed to the induction of CD11b⁺Gr-1⁺ MDSC-like cells via the STAT3/Bv8 axis.

Dietary capsaicin and antibiotics act synergistically to reduce non-alcoholic fatty liver disease induced by high fat diet in mice

The prevalence of non-alcoholic fatty liver disease is increasing rapidly worldwide. However, effective strategies for combating high-fat diet (HFD) induced obesity, fatty liver and metabolic disorder are still limited, and outcomes remain poor. In the present study, we evaluated the combined actions of dietary capsaicin and antibiotics on HFD-induced physiological abnormalities in mice. C57BL/6 male mice were fed with HFD (60% calories from fat) for 17 weeks, and the resultant pathophysiological effects were examined. Antibiotic treatment markedly attenuated gut inflammation and leakiness induced by HFD, whereas capsaicin showed limited effects on the gut. However, dietary capsaicin significantly increased PPAR-α expression in adipose tissue, while antibiotics had no such effect. Animals treated with a combination of capsaicin and antibiotics had the smallest body weight gain and fat pad index, as well as the lowest hepatic fat accumulation. Combination treatment also maximally improved insulin responsiveness, as indicated by insulin tolerance tests. These results suggest the co-treatment of capsaicin and antibiotics, a novel combination strategy, would play synergistically to attenuate the HFD-induced obesity, fatty liver and metabolic disorder.

Enteric dysbiosis-linked gut barrier disruption triggers early renal injury induced by chronic high salt feeding in mice

Chronic high-salt diet-associated renal injury is a key risk factor for the development of hypertension. However, the mechanism by which salt triggers kidney damage is poorly understood. Our study investigated how high salt (HS) intake triggers early renal injury by considering the ‘gut-kidney axis’. We fed mice 2% NaCl in drinking water continuously for 8 weeks to induce early renal injury. We found that the ‘quantitative’ and ‘qualitative’ levels of the intestinal microflora were significantly altered after chronic HS feeding, which indicated the occurrence of enteric dysbiosis. In addition, intestinal immunological gene expression was impaired in mice with HS intake. Gut permeability elevation and enteric bacterial translocation into the kidney were detected after chronic HS feeding. Gut bacteria depletion by non-absorbable antibiotic administration restored HS loading-induced gut leakiness, renal injury and systolic blood pressure elevation. The fecal microbiota from mice fed chronic HS could independently cause gut leakiness and renal injury. Our current work provides a novel insight into the mechanism of HS-induced renal injury by investigating the role of the intestine with enteric bacteria and gut permeability and clearly illustrates that chronic HS loading elicited renal injury and dysfunction that was dependent on the intestine.

Risk factors for extended-spectrum β-lactamase-producing Escherichia coli urinary tract infection in the community in Denmark: a case-control study

OBJECTIVE

To verify the role of proton pump inhibitors (PPI) and nitrofurantoin, which have appeared as novel risk factors for carriage of extended-spectrum β-lactamase (ESBL) -producing Escherichia coli, as risk factors for ESBL E. coli urinary tract infection (UTI). We included known risk factors to ascertain whether our findings are comparable with those of previous studies.

METHODS

Population-based case-control study including 339 cases with community-onset ESBL E. coli UTI in 2007-2012, 3390 non-ESBL E. coli UTI controls and 3390 population controls. We investigated potential risk factors by estimating ORs and 95% CIs adjusting for sex, age and co-morbidity.

RESULTS

Comparing cases with non-ESBL E. coli UTI, PPI use yielded an OR of 1.6 (95% CI 1.2-2.0) and antibiotic exposure gave an OR of 1.4 (95% CI 1.1-1.8); these were driven by nitrofurantoin (OR 1.8; 95% CI 1.3-2.6) and macrolides (OR 1.7; 95% CI 1.2-2.3). Other risk factors included previous hospitalization with one or two and more than two hospitalizations versus none yielding ORs of 1.9 (95% CI 1.4-2.5) and 4.6 (95% CI 3.2-6.8), recent surgery (OR 2.0; 95% CI 1.5-2.8), renal disease (OR 2.2; 95% CI 1.4-3.4), chronic pulmonary disease (OR 1.4; 95% CI 1.0-2.0) and cancer (OR 1.5; 95% CI 1.1-2.1). Comparing cases with population controls, we found that most risk factors were also risk factors for non-ESBL UTI.

CONCLUSIONS

ESBL E. coli UTI were associated with previous hospitalization and surgery. Nitrofurantoin and macrolides augmented the risk. PPIs had a moderate effect but may be important facilitators of ESBL carriage due to their widespread use.

Low-dose penicillin exposure in early life decreases Th17 and the susceptibility to DSS colitis in mice through gut microbiota modification

Antibiotic exposure in early life can lead to a significant change of the gut microbiota and may contribute to later onset of inflammatory bowel disease (IBD). However, the relationship between early-life antibiotic treatment and IBD is ambiguous, according to contradicting results of epidemiologic studies. In the present study, we demonstrated that low-dose penicillin pre-treatment had a unique protective effect against mouse colitis induced by dextran sodium sulfate (DSS). Low-dose penicillin also suppressed the expression of pro-inflammatory cytokine IL-17 in various intestinal tissues, and decreased the amount of Th17 cells in small-intestine lamina propria. Neither metronidazole nor enrofloxacin had a similar effect. We further confirmed that low-dose penicillin could cause specific changes of the gut microbiota, especially the eradication of segmented filamentous bacteria (SFB). Mice without SFB inoculation showed no disparity when treated with penicillin or water. Taken together, the results showed that low-dose penicillin can achieve a highly specific manipulation of sensitive bacteria and interfere with development of intestinal immune system in early life. The study may further indicate the possibility of achieving a favorable immune state among a certain group of patients with IBD, or other autoimmune diseases, by fine-tuning the gut microbiota.

Changes in the diversity and composition of gut microbiota of weaned piglets after oral administration of Lactobacillus or an antibiotic

The gut microbiota plays important roles in the health and well-being of animals, and high-throughput sequencing facilitates exploration of microbial populations in the animal gut. However, previous studies have focused on fecal samples instead of the gastrointestinal tract. In this study, we compared the microbiota diversity and composition of intestinal contents of weaned piglets treated with Lactobacillus reuteri or chlortetracycline (aureomycin) using high-throughput sequencing. Nine weaned piglets were randomly divided into three groups and supplemented with L. reuteri, chlortetracycline, or saline for 10 days, and then the contents of three intestinal segments (jejunum, colon, and cecum) were obtained and used for sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The microbiota diversity and composition in the jejunum were different from those in the colon and cecum among the three treatments. In the jejunum, treatment with L. reuteri increased the species richness of the microbiota, as indicated by the ACE and Chao1 indexes, compared with the chlortetracycline group, in which several taxa were eliminated. In the colon and cecum, relative abundances of the phylum Firmicutes and the genus Prevotella were higher in the chlortetracycline group than in the other groups. Distances between clustered samples revealed that the L. reuteri group was closer to the chlortetracycline group than the control group for jejunum samples, while colon and cecum samples of the L. reuteri group were clustered with those of the control group. This study provides fundamental knowledge for future studies such as the development of alternatives to antibiotics.

Effects of Antibiotics on Gut Microbiota

The gut microbiota influences essential human functions including digestion, energy metabolism, and inflammation by modulating multiple endocrine, neural, and immune pathways of the host. Its composition and complexity varies markedly across individuals and across different sites of the gut, but provides a certain level of resilience against external perturbation. Short-term antibiotic treatment is able to shift the gut microbiota to long-term alternative dysbiotic states, which may promote the development and aggravation of disease. Common features of post-antibiotic dysbiosis include a loss of taxonomic and functional diversity combined with reduced colonization resistance against invading pathogens, which harbors the danger of antimicrobial resistance. This review summarizes the antibiotic-related changes of the gut microbiota and potential consequences in health and disease.