Antibiotic Therapy and the Gut Microbiome: Investigating the Effect of Delivery Route on Gut Pathogens

Black seed oil reverses chronic antibiotic-mediated depression and social behaviour deficits via modulation of hypothalamic mitochondrial-dependent markers and insulin expression

Chronic antibiotic use has been reported to impair mitochondrial indices, hypothalamus-mediated metabolic function, and amygdala-regulated emotional processes. Natural substances such as black seed (Nigella sativa) oil could be beneficial in mitigating these impairments. This study aimed to assess the impact of black seed oil (NSO) on depression and sociability indices, redox imbalance, mitochondrial-dependent markers, and insulin expression in mice subjected to chronic ampicillin exposure. Forty adult male BALB/c mice (30 ± 2 g) were divided into five groups: the CTRL group received normal saline, the ABT group received ampicillin, the NSO group received black seed oil, the ABT/NSO group concurrently received ampicillin and black seed oil, and the ABT+NSO group experienced pre-exposure to ampicillin followed by subsequent treatment with black seed oil. The ampicillin-exposed group exhibited depressive-like behaviours, impaired social interactive behaviours, and disruptions in mitochondrial-dependent markers in plasma and hypothalamic tissues, accompanied by an imbalance in antioxidant levels. Moreover, chronic antibiotic exposure downregulated insulin expression in the hypothalamus. However, these impairments were significantly ameliorated in the ABT/NSO, and ABT+NSO groups compared to the untreated antibiotic-exposed group. Overall, findings from this study suggest the beneficial role of NSO as an adjuvant therapy in preventing and abrogating mood behavioural and neural-metabolic impairments of chronic antibiotic exposure.

Antimicrobial Prophylaxis With Ampicillin-sulbactam Compared With Cefazolin for Esophagectomy: Nationwide Inpatient Database Study in Japan

OBJECTIVE

To assess the effect of antimicrobial prophylaxis with ampicillin-sulbactam (ABPC/SBT) compared with cefazolin (CEZ) on the short-term outcomes after esophagectomy.

BACKGROUND

CEZ is widely used for antimicrobial prophylaxis in esophagectomy without procedure-specific evidence, whereas ABPC/SBT is preferred in some hospitals to target both aerobic and anaerobic oral bacteria.

METHODS

Data of patients who underwent esophagectomy for cancer between July 2010 and March 2019 were extracted from a nationwide Japanese inpatient database. Overlap propensity score weighting was conducted to compare the short-term outcomes [including surgical site infection (SSI), anastomotic leakage, and respiratory failure] between antimicrobial prophylaxis with CEZ and ABPC/SBT after adjusting for potential confounders. Sensitivity analyses were also performed using propensity score matching and instrumental variable analyses.

RESULTS

Among 17,772 eligible patients, 16,077 (90.5%) and 1695 (9.5%) patients were administered CEZ and ABPC/SBT, respectively. SSI, anastomotic leakage, and respiratory failure occurred in 2971 (16.7%), 2604 (14.7%), and 2754 patients (15.5%), respectively. After overlap weighting, ABPC/SBT was significantly associated with a reduction in SSI [odds ratio 0.51 (95% CI: 0.43-0.60)], anastomotic leakage [0.51 (0.43-0.61)], and respiratory failure [0.66 (0.57-0.77)]. ABPC/SBT was also associated with reduced respiratory complications, postoperative length of stay, and total hospitalization costs. The proportion of Clostridioides difficile colitis and noninfectious complications did not differ between the groups. Propensity score matching and instrumental variable analyses demonstrated equivalent results.

CONCLUSIONS

The administration of ABPC/SBT as antimicrobial prophylaxis for esophagectomy was associated with better short-term postoperative outcomes compared with CEZ.

Gut microbial co-metabolite 2-methylbutyrylcarnitine exacerbates thrombosis via binding to and activating integrin α2β1

Thrombosis represents the leading cause of death and disability upon major adverse cardiovascular events (MACEs). Numerous pathological conditions such as COVID-19 and metabolic disorders can lead to a heightened thrombotic risk; however, the underlying mechanisms remain poorly understood. Our study illustrates that 2-methylbutyrylcarnitine (2MBC), a branched-chain acylcarnitine, is accumulated in patients with COVID-19 and in patients with MACEs. 2MBC enhances platelet hyperreactivity and thrombus formation in mice. Mechanistically, 2MBC binds to integrin α2β1 in platelets, potentiating cytosolic phospholipase A2 (cPLA2) activation and platelet hyperresponsiveness. Genetic depletion or pharmacological inhibition of integrin α2β1 largely reverses the pro-thrombotic effects of 2MBC. Notably, 2MBC can be generated in a gut-microbiota-dependent manner, whereas the accumulation of plasma 2MBC and its thrombosis-aggravating effect are largely ameliorated following antibiotic-induced microbial depletion. Our study implicates 2MBC as a metabolite that links gut microbiota dysbiosis to elevated thrombotic risk, providing mechanistic insight and a potential therapeutic strategy for thrombosis.

Characterization of urban sources of antibiotics and antibiotic-resistance genes in a Dutch sewer catchment

A one year study was conducted in the city of Nijmegen, The Netherlands, to characterize various urban sources of antibiotics and antibiotic resistant genes (ARGs) in wastewater within a single sewer catchment. Prevalence of ermB, tet(W), sul1, sul2, intl1, and 16S rRNA gene was determined at 10 locations within the city. Sampling locations included a nursing home, a student residence, a hospital and an industrial area, among others. Wastewater concentrations of 23 antibiotics were measured using passive sampling. Additionally, excreted loads of 22 antibiotics were estimated based on ambulatory prescription and clinical usage data. Genes sul1 and intl1 were most abundant across most locations. Ciprofloxacin and amoxicillin together contributed over 92 % of the total estimated antibiotic selective pressure at all sampling points. The present study highlights the prominent role that hospitals can have in the prevalence and proliferation of ARGs in urban wastewater. Furthermore, results suggest that even short-term changes in the therapeutic regimen prescribed in hospitals may translate into shifting ARG abundance patterns in hospital wastewater. The methods applied present an opportunity to identify emission hotspots and prioritize intervention options to limit ARG spread from urban wastewater to the environment.

Antibiotic-induced collateral damage to the microbiota and associated infections

Antibiotics have transformed medicine, saving millions of lives since they were first used to treat a bacterial infection. However, antibiotics administered to target a specific pathogen can also cause collateral damage to the patient's resident microbial population. These drugs can suppress the growth of commensal species which provide protection against colonization by foreign pathogens, leading to an increased risk of subsequent infection. At the same time, a patient's microbiota can harbour potential pathogens and, hence, be a source of infection. Antibiotic-induced selection pressure can cause overgrowth of resistant pathogens pre-existing in the patient's microbiota, leading to hard-to-treat superinfections. In this Review, we explore our current understanding of how antibiotic therapy can facilitate subsequent infections due to both loss of colonization resistance and overgrowth of resistant microorganisms, and how these processes are often interlinked. We discuss both well-known and currently overlooked examples of antibiotic-associated infections at various body sites from various pathogens. Finally, we describe ongoing and new strategies to overcome the collateral damage caused by antibiotics and to limit the risk of antibiotic-associated infections.

Antibiotic use and development of nonalcoholic fatty liver disease: A population-based case-control study

BACKGROUND AND AIMS

Antibiotics affect the gut microbiome. Preclinical studies suggest a role of gut dysbiosis in the development of nonalcoholic fatty liver disease (NAFLD), but data from large cohorts with liver histology are lacking.

METHODS

In this nationwide case-control study, Swedish adults with histologically confirmed early-stage NAFLD (total n = 2584; simple steatosis n = 1435; steatohepatitis (NASH) n = 383; non-cirrhotic fibrosis n = 766) diagnosed January 2007-April 2017 were included and matched to ≤5 population controls (n = 12 646) for age, sex, calendar year and county of residence. Data for cumulative antibiotic dispensations and defined daily doses were accrued until 1 year before the matching date. Using conditional logistic regression, multivariable-adjusted odds ratios (aORs) were calculated. In a secondary analysis, NAFLD patients were compared with their full siblings (n = 2837).

RESULTS

Previous antibiotic use was seen in 1748 (68%) NAFLD patients versus 7001 (55%) controls, corresponding to 1.35-fold increased odds of NAFLD (95% CI = 1.21-1.51) in a dose-dependent manner (pfor trend  < .001). Estimates were comparable for all histologic stages (p > .05). The highest risk of NAFLD was observed after treatment with fluoroquinolones (aOR 1.38; 95% CI = 1.17-1.59). Associations remained robust when patients were compared with their full siblings (aOR 1.29; 95% CI = 1.08-1.55). Antibiotic treatment was only linked to NAFLD in patients without metabolic syndrome (aOR 1.63; 95% CI = 1.35-1.91) but not in those with metabolic syndrome (aOR 1.09; 95% CI = 0.88-1.30).

CONCLUSIONS

Antibiotic use may be a risk factor for incident NAFLD, especially in individuals without the metabolic syndrome. The risk was highest for fluoroquinolones and remained robust in sibling comparisons with whom individuals share genetic and early environmental susceptibilities.

Prolonged Antibiotic Exposure during Adolescence Dysregulates Liver Metabolism and Promotes Adiposity in Mice

Antibiotic administration during early life has been shown to have lasting effects on the gut microbiota, which have been linked to sustained alterations in liver metabolism and adiposity. Recent investigations have discerned that the gut microbiota continues to develop toward an adult-like profile during adolescence. However, the impact of antibiotic exposure during adolescence on metabolism and adiposity is unclear. Herein, a retrospective analysis of Medicaid claims data was performed, which indicated that tetracycline class antibiotics are commonly prescribed for the systemic treatment of adolescent acne. The purpose of this was to discern the impact of a prolonged tetracycline antibiotic exposure during adolescence on the gut microbiota, liver metabolism, and adiposity. Male C57BL/6T specific pathogen-free mice were administered a tetracycline antibiotic during the pubertal/postpubertal adolescent growth phase. Groups were euthanized at different time points to assess immediate and sustained antibiotic treatment effects. Antibiotic exposure during adolescence caused lasting genera-level shifts in the intestinal bacteriome and persistent dysregulation of metabolic pathways in the liver. Dysregulated hepatic metabolism was linked to sustained disruption of the intestinal farnesoid X receptor-fibroblast growth factor 15 axis, a gut-liver endocrine axis that supports metabolic homeostasis. Antibiotic exposure during adolescence increased subcutaneous, visceral, and marrow adiposity, which intriguingly manifested following antibiotic therapy. This preclinical work highlights that prolonged antibiotic courses for the clinical treatment of adolescent acne may have unintended deleterious effects on liver metabolism and adiposity.

The spread of antibiotic resistance to humans and potential protection strategies

Antibiotic resistance is currently one of the greatest threats to human health. Widespread use and residues of antibiotics in humans, animals, and the environment can exert selective pressure on antibiotic resistance bacteria (ARB) and antibiotic resistance gene (ARG), accelerating the flow of antibiotic resistance. As ARG spreads to the population, the burden of antibiotic resistance in humans increases, which may have potential health effects on people. Therefore, it is critical to mitigate the spread of antibiotic resistance to humans and reduce the load of antibiotic resistance in humans. This review briefly described the information of global antibiotic consumption information and national action plans (NAPs) to combat antibiotic resistance and provided a set of feasible control strategies for the transmission of ARB and ARG to humans in three areas including (a) Reducing the colonization capacity of exogenous ARB, (b) Enhancing human colonization resistance and mitigating the horizontal gene transfer (HGT) of ARG, (c) Reversing ARB antibiotic resistance. With the hope of achieving interdisciplinary one-health prevention and control of bacterial resistance.

Assessment of the impact of intravenous antibiotics treatment on gut microbiota in patients: Clinical data from pre-and post-cardiac surgery

Background and aims

Surgical site infection is a common complication after surgery. Periprocedural antibiotics are necessary to prescribe for preventing or treating infections. The present study aimed to explore the effect of intravenous antibiotics on gut microbiota and menaquinone biosynthesis in patients, especially in elderly patients undergoing cardiac surgery.

Methods

A total of 388 fecal samples were collected from 154 cardiac surgery patients. The V3-V4 hypervariable region of the bacterial 16S rRNA gene was amplified and sequenced on a MiSeq PE300. The gut microbiota diversity of samples was analyzed in terms of α- and β-diversity at the OTU level. The different groups were classified according to antibiotics in combinations and single antibiotics. PICRUSt2 was used for preliminary prediction of the gut microbiota function for menaquinone biosynthesis.

Results

The intravenously administered antibiotics which are excreted via bile represents the main antibiotics that could disturb the gut microbiota's composition in cardiac surgery patients, especially for elderly patients. The effect of antibiotics on gut microbiota is produced after antibiotics treatments over one week. The recovery of gut microbiota to the state of pre-antibiotics may require over two weeks of antibiotics withdrawal. Sex factor doesn't represent as an influencer in gut microbiota composition. Long-term use of cefoperazone-sulbactam may affect coagulation function.

Conclusions

The composition of the gut microbiota had a significant change post-intravenous antibiotics treatment in cardiac surgery patients. The richness and diversity of gut microbiota are increased in elderly patients.

The lung, the niche, and the microbe: Exploring the lung microbiome in cancer and immunity

The lung is a complex and unique organ system whose biology is strongly influenced by environmental exposure, oxygen abundance, connection to extrapulmonary systems via a dense capillary network, and an array of immune cells that reside in the tissue at steady state. The lung also harbors a low biomass community of commensal microorganisms that are dynamic during both health and disease with the capacity to modulate regulatory immune responses during diseases such as cancer. Lung cancer is the third most common cancer worldwide with the highest mortality rate amongst cancers due to the difficulty of an early diagnosis. This review discusses the current body of work addressing the interactions between the lung microbiota and the immune system, and how these two components of the pulmonary system are linked to lung cancer development and outcomes. Bringing in lessons from broader studies examining the effects of the gut microbiota on cancer outcomes, we highlight many challenges and gaps in this nascent field.

Pulmonary microbiota intervention alleviates fine particulate matter-induced lung inflammation in broilers

Fine particulate matter (PM2.5) released during the livestock industry endangers the respiratory health of animals. Our previous findings suggested that broilers exposed to PM2.5 exhibited lung inflammation and changes in the pulmonary microbiome. Therefore, this study was to investigate whether the pulmonary microbiota plays a causal role in the pathogenesis of PM2.5-induced lung inflammation. We first used antibiotics to establish a pulmonary microbiota intervention broiler model, which showed a significantly reduced total bacterial load in the lungs without affecting the microbiota composition or structure. Based on it, 45 AA broilers of similar body weight were randomly assigned to three groups: control (CON), PM2.5 (PM), and pulmonary microbiota intervention (ABX-PM). From 21 d of age, broilers in the ABX-PM group were intratracheally instilled with antibiotics once a day for 3 d. Meanwhile, broilers in the other two groups were simultaneously instilled with sterile saline. On 24 and 26 d of age, broilers in the PM and ABX-PM groups were intratracheally instilled with PM2.5 suspension to induce lung inflammation, and broilers in the CON group were simultaneously instilled with sterile saline. The lung histomorphology, inflammatory cytokines' expression levels, lung microbiome, and microbial growth conditions were analyzed to determine the effect of the pulmonary microbiota on PM2.5-induced lung inflammation. Broilers in the PM group showed lung histological injury, while broilers in the ABX-PM group had normal lung histomorphology. Furthermore, microbiota intervention significantly reduced mRNA expression levels of interleukin-1β, tumor necrosis factor-α, interleukin-6, interleukin-8, toll-like receptor 4 and nuclear factor kappa-B. PM2.5 induced significant changes in the β diversity and structure of the pulmonary microbiota in the PM group. However, no significant changes in microbiota structure were observed in the ABX-PM group. Moreover, the relative abundance of Enterococcus cecorum in the PM group was significantly higher than that in the CON and ABX-PM groups. And sterile bronchoalveolar lavage fluid from the PM group significantly promoted the growth of E. cecorum, indicating that PM2.5 altered the microbiota's growth condition. In conclusion, pulmonary microbiota can affect PM2.5-induced lung inflammation in broilers. PM2.5 can alter the bacterial growth environment and promote dysbiosis, potentially exacerbating inflammation.

Antibiotic use and the development of depression: A systematic review

OBJECTIVE

Increasingly, disruption of the gastrointestinal ecosystem is thought to be involved in the pathogenesis of several medical conditions, including depression. Antibiotics can induce substantial changes in the gastrointestinal microbiota and several lines of evidence suggest that antibiotics exposure may increase the risk of developing depression. This systematic review examined this potential association.

METHODS

PubMed, Ovid EMBASE, CINAHL, and PsychINFO databases, as well as unpublished resources, were searched for studies in humans published from 2000 onwards. The studies needed to consider the connection between antibiotic exposure (either alone or in combination with other antibiotics and medications) and the development of depressive symptoms and/or disorders (in isolation to other psychological conditions).

RESULTS

Nine studies met the eligibility criteria. All were observational in nature. The studies were conducted in different age groups with various indications for receiving antibiotics. Together, these relatively low-quality studies suggest a potential association between antibiotic exposure and subsequent development of depression symptoms. Specifically, studies from the United Kingdom and Sweden indicate that the risk of depression is increased by at least 20%, with the former (over 1 million participants) reporting an increased risk with the number of courses and agents used, that persists with a slow decline over the ten years following exposure.

CONCLUSIONS

The inherent limitations associated with the studies' methodologies make a reliable conclusion difficult. While the risk of antimicrobial resistance may prohibit large randomised clinical trials in healthy individuals, future placebo-controlled trials with antibiotics-based protocols (e.g. for acne) should explore their effect on mental health.

An insight into the commercial piglet's microbial gut colonization: from birth towards weaning

BACKGROUND

The establishment of the gut microbiota can be influenced by several perinatal factors, including, most importantly, the maternal microbiota. Moreover, early-life environmental variation affects gut microbial colonization and the intestinal health of offspring throughout life. The present study aimed to explore the development of piglet gut microbiota from birth to weaning in the commercial practice and also to assess how different farm environments could condition this process. Although it is possible to find in the literature other studies with similar objectives this work probably represents one of the few studies that make a systematic evaluation of such differential factors under a real scenario. To achieve this objective, we performed two trials. In a first Trial, we selected 2 farms in which we performed an intensive sampling (5 samples /animal) to characterize the gut colonization pattern during the first days of life and to identify the time window with the greatest impact. Both farms differed in their health status and the use of antimicrobials in the piglets. In a second Trial, we selected 4 additional farms with variable rearing conditions and a distinctive use of antimicrobials in the sows with a simplified sampling pattern (2 samples/animal). Faecal samples were obtained with swabs and DNA was extracted by using the PSP® Spin Stool DNA Kit and sequencing of the 16S rRNA gene (V3-V4 region) performed by Illumina MiSeq Platform.

RESULTS

The present study contributes to a better understanding of microbiome development during the transition from birth to weaning in commercial conditions. Alpha diversity was strongly affected by age, with an increased richness of species through time. Beta diversity decreased after weaning, suggesting a convergent evolvement among individuals. We pinpointed the early intestinal colonizers belonging to Bacteroides, Escherichia-Shigella, Clostridium sensu stricto 1, and Fusobacterium genera. During lactation(d7-d21 of life), the higher relative abundances of Bacteroides and Lactobacillus genera were correlated with a milk-oriented microbiome. As the piglets aged and after weaning (d36 of life), increasing abundances of genera such as Prevotella, Butyricimonas, Christensenellaceae R-7 group, Dorea, Phascolarctobacterium, Rikenellaceae RC9 gut group, Subdoligranulum, and Ruminococcaceae UCG-002 were observed. These changes indicate the adaptation of the piglets to a cereal-based diet rich in oligosaccharides and starch. Our results also show that the farm can have a significant impact in such a process, evidencing the influence of different environments and rearing systems on the gut microbiota development of the young piglet. Differences between farms were more noticeable after weaning than during lactation with changes in alpha and beta biodiversity and specific taxa. The analysis of such differences suggests that piglets receiving intramuscular amoxicillin (days 2-5 of life) and being offered an acidifying rehydrating solution (Alpha farm in Trial 1) have a greater alpha diversity and more abundant Lactobacillus population. Moreover, the only farm that did not offer any rehydrating solution (Foxtrot farm in Trial 2) showed a lower alpha diversity (day 2 of life) and increased abundance of Enterobacteriaceae (both at 2 and 21 days). The use of in-feed antibiotics in the sows was also associated with structural changes in the piglets' gut ecosystem although without changes in richness or diversity. Significant shifts could be registered in different microbial groups, particularly lower abundances of Fusobacterium in those piglets from medicated sows.

CONCLUSIONS

In conclusion, during the first weeks of life, the pig microbiota showed a relevant succession of microbial groups towards a more homogeneous and stable ecosystem better adapted to the solid dry feed. In this relevant early-age process, the rearing conditions, the farm environment, and particularly the antimicrobial use in piglets and mothers determine changes that could have a relevant impact on gut microbiota maturation. More research is needed to elucidate the relative impact of these farm-induced early life-long changes in the growing pig.

Quinolones as a Potential Drug in Genitourinary Cancer Treatment-A Literature Review

Quinolones, broad-spectrum antibiotics, are frequently prescribed by urologists for many urological disorders. The mechanism of their bactericidal activity is based on the inhibition of topoisomerase II or IV complex with DNA, which consequently leads to cell death. It has been observed that these antibiotics also act against the analogous enzymes present in eukaryotic cells. Due to their higher accumulation in urine and prostate tissue than in serum, these drugs seem to be ideal candidates for application in genitourinary cancer treatment. In this study, an extensive literature review has been performed to collect information about concentrations achievable in urine and prostate tissue together with information about anticancer properties of 15 quinolones. Special attention was paid to the application of cytotoxic properties of quinolones for bladder and prostate cancer cell lines. Data available in the literature showed promising properties of quinolones, especially in the case of urinary bladder cancer treatment. In the case of prostate cancer, due to low concentrations of quinolones achievable in prostate tissue, combination therapy with other chemotherapeutics or another method of drug administration is necessary.

The Role of the Gut Microbiota in the Development of Ischemic Stroke

An increasing number of studies have focused on the gut microbiota and its relationship with various neurological diseases. The gut microbiota can affect the metabolic status of the body, in addition to having an important impact on blood pressure, blood glucose, and atherosclerosis, all of which are risk factors for ischemic stroke. In this review, we summarized studies that included the physiological function of the gut microbiota and gut microbiota disorders related to the central nervous system, thus providing novel ideas for the prevention and treatment of ischemic stroke.

Antibiotic Therapy and Risk of Early-Onset Colorectal Cancer: A National Case-Control Study

INTRODUCTION

Antibiotic use has emerged as a risk factor for colorectal neoplasia and is hypothesized as a contributor to the rising incidence of colorectal cancer under age 50 years or early-onset colorectal cancer (EOCRC). However, the impact of antibiotic use and risk of EOCRC is unknown.

METHODS

We conducted a population-based case-control study of CRC among individuals aged ≥18 years in the Epidemiology Strengthened by histoPathology Reports in Sweden (ESPRESSO) cohort (2006-2016). The primary outcome was EOCRC. A secondary outcome was CRC at any age. Incident CRC was pathologically confirmed, and for each, up to 5 population-based controls were matched on age, sex, county of residence, and calendar year. We assessed prescriptions until 6 months before CRC diagnosis. Conditional logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

We identified 54,804 cases of CRC (2,557 EOCRCs) and 261,089 controls. Compared with none, previous antibiotic use was not associated with EOCRC risk after adjustment for potential confounders (aOR 1.06, 95% CI: 0.96, 1.17) with similarly null findings when stratified by anatomic tumor site. In contrast, previous antibiotic use was weakly associated with elevated risk for CRC at any age (aOR 1.05, 95% CI: 1.02, 1.07). A potential but modest link between broad-spectrum antibiotic use and EOCRC was observed (aOR 1.13, 95% CI: 1.02, 1.26).

DISCUSSION

We found no conclusive evidence that antibiotics are associated with EOCRC risk. Although antibiotic use was weakly associated with risk of CRC at any age, the magnitude of association was modest, and the study period was relatively short.

Impact of Antibiotic Therapies on Resistance Genes Dynamic and Composition of the Animal Gut Microbiota

Antibiotics are major disruptors of the gastrointestinal microbiota, depleting bacterial species beneficial for the host health and favoring the emergence of potential pathogens. Furthermore, the intestine is a reactor of antibiotic resistance emergence, and the presence of antibiotics exacerbates the selection of resistant bacteria that can disseminate in the environment and propagate to further hosts. We reviewed studies analyzing the effect of antibiotics on the intestinal microbiota and antibiotic resistance conducted on animals, focusing on the main food-producing and companion animals. Irrespective of antibiotic classes and animal hosts, therapeutic dosage decreased species diversity and richness favoring the bloom of potential enteropathogens and the selection of antibiotic resistance. These negative effects of antibiotic therapies seem ineluctable but often were mitigated when an antibiotic was administered by parenteral route. Sub-therapeutic dosages caused the augmentation of taxa involved in sugar metabolism, suggesting a link with weight gain. This result should not be interpreted positively, considering that parallel information on antibiotic resistance selection was rarely reported and selection of antibiotic resistance is known to occur also at low antibiotic concentration. However, studies on the effect of antibiotics as growth promoters put the basis for understanding the gut microbiota composition and function in this situation. This knowledge could inspire alternative strategies to antibiotics, such as probiotics, for improving animal performance. This review encompasses the analysis of the main animal hosts and all antibiotic classes, and highlights the future challenges and gaps of knowledge that should be filled. Further studies are necessary for elucidating pharmacodynamics in animals in order to improve therapy duration, antibiotic dosages, and administration routes for mitigating negative effects of antibiotic therapies. Furthermore, this review highlights that studies on aminoglycosides are almost inexistent, and they should be increased, considering that aminoglycosides are the first most commonly used antibiotic family in companion animals. Harmonization of experimental procedures is necessary in this research field. In fact, current studies are based on different experimental set-up varying for antibiotic dosage, regimen, administration, and downstream microbiota analysis. In the future, shotgun metagenomics coupled with long-reads sequencing should become a standard experimental approach enabling to gather comprehensive knowledge on GIM in terms of composition and taxonomic functions, and of ARGs. Decorticating GIM in animals will unveil revolutionary strategies for medication and improvement of animals' health status, with positive consequences on global health.

Selective Inhibition of Helicobacter pylori Carbonic Anhydrases by Carvacrol and Thymol Could Impair Biofilm Production and the Release of Outer Membrane Vesicles

Helicobacter pylori, a Gram-negative neutrophilic pathogen, is the cause of chronic gastritis, peptic ulcers, and gastric cancer in humans. Current therapeutic regimens suffer from an emerging bacterial resistance rate and poor patience compliance. To improve the discovery of compounds targeting bacterial alternative enzymes or essential pathways such as carbonic anhydrases (CAs), we assessed the anti-H. pylori activity of thymol and carvacrol in terms of CA inhibition, isoform selectivity, growth impairment, biofilm production, and release of associated outer membrane vesicles-eDNA. The microbiological results were correlated by the evaluation in vitro of H. pylori CA inhibition, in silico analysis of the structural requirements to display such isoform selectivity, and the assessment of their limited toxicity against three probiotic species with respect to amoxicillin. Carvacrol and thymol could thus be considered as new lead compounds as alternative H. pylori CA inhibitors or to be used in association with current drugs for the management of H. pylori infection and limiting the spread of antibiotic resistance.