Bacterial, Gut Microbiome-Modifying Therapies to Defend against Multidrug Resistant Organisms

Seasonal variations of airborne microbial diversity in waste transfer stations and preventive effect on Streptococcus pneumoniae induced pulmonary inflammation

Environment, location, and season are important factors that influence the microbiological community, yet, little research on airborne microorganisms in waste transfer stations (WTSs). Here, the airborne bacterial and fungal communities at four WTSs during different seasons were analyzed by high-throughput sequencing. The bacteria were isolated by cultural method and screened bacterium alleviate inflammation induced by Streptococcus pneumoniae (Spn) by regulating gut microbiome. The results revealed that collected bioaerosols from the WTSs varied significantly by location and season. Proteobacteria and Pseudomonadota are prevalent in summer and winter, respectively. Ascomycota was predominant in two seasons. Hazard quotients for adults from four WTSs were below one. Three selected potential probiotics were formulated into a microbial preparation with a carrier that effectively prevented inflammation in bacterial and animal experiments. The expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α in Pre group (0.11, 0.17, and 0.48-fold) were significantly lower than Spn group (2.75, 1.71, and 5.01-fold). These mechanisms are associated with changes in gut microbiota composition and short-chain fatty acids (SCFAs) levels, such as affecting Lachnospiraceae lachnospira abundance and acetic acid content. This study provides insights into the potential application of probiotics derived from WTSs as an alternative approach to preventing respiratory infections.

Translating eco-evolutionary biology into therapy to tackle antibiotic resistance

Antibiotic resistance is currently one of the most important public health problems. The golden age of antibiotic discovery ended decades ago, and new approaches are urgently needed. Therefore, preserving the efficacy of the antibiotics currently in use and developing compounds and strategies that specifically target antibiotic-resistant pathogens is critical. The identification of robust trends of antibiotic resistance evolution and of its associated trade-offs, such as collateral sensitivity or fitness costs, is invaluable for the design of rational evolution-based, ecology-based treatment approaches. In this Review, we discuss these evolutionary trade-offs and how such knowledge can aid in informing combination or alternating antibiotic therapies against bacterial infections. In addition, we discuss how targeting bacterial metabolism can enhance drug activity and impair antibiotic resistance evolution. Finally, we explore how an improved understanding of the original physiological function of antibiotic resistance determinants, which have evolved to reach clinical resistance after a process of historical contingency, may help to tackle antibiotic resistance.

Insights on Current Strategies to Decolonize the Gut from Multidrug-Resistant Bacteria: Pros and Cons

In the last decades, we have witnessed a steady increase in infections caused by multidrug-resistant (MDR) bacteria. These infections are associated with higher morbidity and mortality. Several interventions should be taken to reduce the emergence and spread of MDR bacteria. The eradication of resistant pathogens colonizing specific human body sites that would likely cause further infection in other sites is one of the most conventional strategies. The objective of this narrative mini-review is to compile and discuss different strategies for the eradication of MDR bacteria from gut microbiota. Here, we analyse the prevalence of MDR bacteria in the community and the hospital and the clinical impact of gut microbiota colonisation with MDR bacteria. Then, several strategies to eliminate MDR bacteria from gut microbiota are described and include: (i) selective decontamination of the digestive tract (SDD) using a cocktail of antibiotics; (ii) the use of pre and probiotics; (iii) fecal microbiota transplantation; (iv) the use of specific phages; (v) engineered CRISPR-Cas Systems. This review intends to provide a state-of-the-art of the most relevant strategies to eradicate MDR bacteria from gut microbiota currently being investigated.

Novel Dietary Approach with Probiotics, Prebiotics, and Synbiotics to Mitigate Antimicrobial Resistance and Subsequent Out Marketplace of Antimicrobial Agents: A Review

Antimicrobial resistance (AMR) is a significant public health concern worldwide. The continuous use and misuse of antimicrobial agents have led to the emergence and spread of resistant strains of bacteria, which can cause severe infections that are difficult to treat. One of the reasons for the constant development of new antimicrobial agents is the need to overcome the resistance that has developed against existing drugs. However, this approach is not sustainable in the long term, as bacteria can quickly develop resistance to new drugs as well. Additionally, the development of new drugs is costly and time-consuming, and there is no guarantee that new drugs will be effective or safe. An alternative approach to combat AMR is to focus on improving the body's natural defenses against infections by using probiotics, prebiotics, and synbiotics, which are helpful to restore and maintain a healthy balance of bacteria in the body. Probiotics are live microorganisms that can be consumed as food or supplements to promote gut health and improve the body's natural defenses against infections. Prebiotics are non-digestible fibers that stimulate the growth of beneficial bacteria in the gut, while synbiotics are a combination of probiotics and prebiotics that work together to improve gut health. By promoting a healthy balance of bacteria in the body, these can help to reduce the risk of infections and the need for antimicrobial agents. Additionally, these approaches are generally safe and well tolerated, and they do not contribute to the development of AMR. In conclusion, the continuous development of new antimicrobial agents is not a sustainable approach to combat AMR. Instead, alternative approaches such as probiotics, prebiotics, and synbiotics should be considered as they can help to promote a healthy balance of bacteria in the body and reduce the need for antibiotics.

Faecal microbiota transplantation reduces amounts of antibiotic resistance genes in patients with multidrug-resistant organisms

Background

Multidrug-resistant organisms (MDROs) such as vancomycin-resistant enterococci (VRE) and carbapenemase-producing Enterobacteriaceae (CPE) are associated with prolonged hospitalisation, increased medical costs, and severe infections. Faecal microbiota transplantation (FMT) has emerged as an important strategy for decolonisation. This study aimed to evaluate the genetic response of MDROs to FMT.

Methods

A single-centre prospective study was conducted on patients infected with VRE, CPE, or VRE/CPE who underwent FMT between May 2018 and April 2019. Genetic response was assessed as the change in the expression of the resistance genes VanA, bla_KPC, bla_NDM, and bla_OXA on days 1, 7, 14, and 28 by real-time reverse-transcription polymerase chain reaction.

Results

Twenty-nine patients received FMT, of which 26 (59.3%) were infected with VRE, 5 (11.1%) with CPE, and 8 (29.6%) with VRE/CPE. The mean duration of MDRO carriage before FMT was 71 days. Seventeen patients (63.0%) used antibiotics within a week of FMT. In a culture-dependent method, the expression of VanA and overall genes significantly decreased (p = 0.011 and p = 0.003 respectively). In a culture-independent method, VanA, bla_NDM, and overall gene expression significantly decreased over time after FMT (p = 0.047, p = 0.048, p = 0.002, respectively). Similar results were confirmed following comparison between each time point in both the culture-dependent and -independent methods. Regression analysis did not reveal important factors underlying the genetic response after FMT. No adverse events were observed.

Conclusion

FMT in patients infected with MDROs downregulates the expression of resistance genes, especially VanA, and facilitates MDRO decolonisation.

Microcin MccI47 selectively inhibits enteric bacteria and reduces carbapenem-resistant Klebsiella pneumoniae colonization in vivo when administered via an engineered live biotherapeutic

The gastrointestinal (GI) tract is the reservoir for multidrug resistant (MDR) pathogens, specifically carbapenem-resistant (CR) Klebsiella pneumoniae and other Enterobacteriaceae, which often lead to the spread of antimicrobial resistance genes, severe extraintestinal infections, and lethal outcomes. Selective GI decolonization has been proposed as a new strategy for preventing transmission to other body sites and minimizing spreading to susceptible individuals. Here, we purify the to-date uncharacterized class IIb microcin I47 (MccI47) and demonstrate potent inhibition of numerous Enterobacteriaceae, including multidrug-resistant clinical isolates, in vitro at concentrations resembling those of commonly prescribed antibiotics. We then genetically modify the probiotic bacterium Escherichia coli Nissle 1917 (EcN) to produce MccI47 from a stable multicopy plasmid by using MccI47 toxin production in a counterselection mechanism to engineer one of the native EcN plasmids, which renders provisions for inducible expression and plasmid selection unnecessary. We then test the clinical relevance of the MccI47-producing engineered EcN in a murine CR K. pneumoniae colonization model and demonstrate significant MccI47-dependent reduction of CR K. pneumoniae abundance after seven days of daily oral live biotherapeutic administration without disruption of the resident microbiota. This study provides the first demonstration of MccI47 as a potent antimicrobial against certain Enterobacteriaceae, and its ability to significantly reduce the abundance of CR K. pneumoniae in a preclinical animal model, when delivered from an engineered live biotherapeutic product. This study serves as the foundational step toward the use of engineered live biotherapeutic products aimed at the selective removal of MDR pathogens from the GI tract.

Decolonization of carbapenem-resistant Klebsiella pneumoniae from the intestinal microbiota of model mice by phages targeting two surface structures

Background

Klebsiella pneumoniae is a normal component of the human gastrointestinal tract microbiota. However, in some cases, it can cause disease. Over the past 20 years, the prevalence of antibiotic-resistant bacteria, such as carbapenem-resistant K. pneumoniae (CRKP), has been increasing.

Materials and methods

We attempted to specifically eliminate CRKP from a mouse model with the human intestinal microbiota. To establish humanized microbiota-colonized mice, we administered K64 CRKP-containing human microbiota to germ-free mice by fecal microbiota transplantation. Then, we used two phages, one targeting the capsule (φK64-1) and one targeting O1 lipopolysaccharide (φKO1-1) of K64 K. pneumoniae, to eliminate CRKP.

Results

In untreated control and φKO1-1-treated K64-colonized mice, no change in CRKP was observed, while in mice treated with φK64-1, a transient reduction was observed. In half of the mice treated with both φKO1-1 and φK64-1, CRKP was undetectable in feces by PCR and culture for 60 days. However, in the other 50% of the mice, K. pneumoniae was transiently reduced but recovered 35 days after treatment.

Conclusion

Combination treatment with φK64-1 and φKO1-1 achieved long-term decolonization in 52.3% of mice carrying CRKP. Importantly, the composition of the intestinal microbiota was not altered after phage treatment. Therefore, this strategy may be useful not only for eradicating drug-resistant bacterial species from the intestinal microbiota but also for the treatment of other dysbiosis-associated diseases.

Faecal microbiota replacement to eradicate antimicrobial resistant bacteria in the intestinal tract - a systematic review

PURPOSE OF REVIEW

Antimicrobial resistance is a rising threat to global health and is associated with increased mortality. Intestinal colonisation with multidrug-resistant organisms (MDRO) can precede invasive infection and facilitates spread within communities and hospitals. Novel decolonisation strategies, such as faecal microbiota transplantation (FMT), are being explored. The purpose of this review is to provide an update on how the field of FMT for MDRO decolonisation has developed during the past year and to assess the efficacy of FMT for intestinal MDRO decolonisation.

RECENT FINDINGS

Since 2020, seven highly heterogenous, small, nonrandomised cohort studies and five case reports have been published. In line with previous literature, decolonisation rates ranged from 20 to 90% between studies and were slightly higher for carbapenem-resistant Enterobacteriaceae than vancomycin-resistant Enterococcus. Despite moderate decolonisation rates in two studies, a reduction in MDRO bloodstream and urinary tract infections was observed.

SUMMARY AND IMPLICATIONS

Although a number of smaller cohort studies show some effect of FMT for MDRO decolonisation, questions remain regarding the true efficacy of FMT (taking spontaneous decolonisation into account), the optimal route of administration, the role of antibiotics pre and post-FMT and the efficacy in different patient populations. The observed decrease in MDRO infections post-FMT warrants further research.

Antibiotics and fecal transfaunation differentially affect microbiota recovery, associations, and antibiotic resistance in lemur guts

BACKGROUND

Antibiotics alter the diversity, structure, and dynamics of host-associated microbial consortia, including via development of antibiotic resistance; however, patterns of recovery from microbial imbalances and methods to mitigate associated negative effects remain poorly understood, particularly outside of human-clinical and model-rodent studies that focus on outcome over process. To improve conceptual understanding of host-microbe symbiosis in more naturalistic contexts, we applied an ecological framework to a non-traditional, strepsirrhine primate model via long-term, multi-faceted study of microbial community structure before, during, and following two experimental manipulations. Specifically, we administered a broad-spectrum antibiotic, either alone or with subsequent fecal transfaunation, to healthy, male ring-tailed lemurs (Lemur catta), then used 16S rRNA and shotgun metagenomic sequencing to longitudinally track the diversity, composition, associations, and resistomes of their gut microbiota both within and across baseline, treatment, and recovery phases.

RESULTS

Antibiotic treatment resulted in a drastic decline in microbial diversity and a dramatic alteration in community composition. Whereas microbial diversity recovered rapidly regardless of experimental group, patterns of microbial community composition reflected long-term instability following treatment with antibiotics alone, a pattern that was attenuated by fecal transfaunation. Covariation analysis revealed that certain taxa dominated bacterial associations, representing potential keystone species in lemur gut microbiota. Antibiotic resistance genes, which were universally present, including in lemurs that had never been administered antibiotics, varied across individuals and treatment groups.

CONCLUSIONS

Long-term, integrated study post antibiotic-induced microbial imbalance revealed differential, metric-dependent evidence of recovery, with beneficial effects of fecal transfaunation on recovering community composition, and potentially negative consequences to lemur resistomes. Beyond providing new perspectives on the dynamics that govern host-associated communities, particularly in the Anthropocene era, our holistic study in an endangered species is a first step in addressing the recent, interdisciplinary calls for greater integration of microbiome science into animal care and conservation.

Factors Associated With Short-Term Eradication of Rectal Colonization by KPC-2 Producing Klebsiella pneumoniae in an Outbreak Setting

Background: KPC-producing Klebsiella pneumoniae (KPCKP) is a threat for patients admitted to healthcare institutions.

Objectives: To assess the efficacy of several decolonization strategies for KPCKP rectal carriage.

Methods: Observational study performed in a 750-bed university center from July to October 2018 on the efficacy of a 10-day non-absorbable oral antibiotic (NAA) regimen (colistin 10 mg/ml, amikacin 8 mg/ml, and nystatin 30 mg/ml, 10 ml/6 h) vs. the same regimen followed by a probiotic (Vivomixx®) for 20 days in adult patients with KPCKP rectal colonization acquired during an outbreak.

Results: Seventy-three patients colonized by KPCKP were included, of which 21 (29%) did not receive any treatment and 52 (71.2%) received NAA either alone (n = 26, 35.6%) or followed by a probiotic (n = 26, 35.6%). Eradication was observed in 56 (76.7%) patients and the only variable significantly associated with it was not receiving systemic antibiotics after diagnosis of rectal carriage [22/24 (91.6%) vs. 34/49 (69.3%), p = 0.04]. Eradication in patients receiving NAA plus probiotic was numerically but not significantly higher than that of controls [23/26 (88.4%) vs. 15/21 (71.4%), p = 0.14] and of those receiving only NAA (OR = 3.4, 95% CI = 0.78–14.7, p = 0.09).

Conclusion: In an outbreak setting, rectal carriage of KPCKP persisted after a mean of 36 days in about one quarter of patients. The only factor associated with eradication was not receiving systemic antibiotic after diagnosis. A 10-day course of NAA had no impact on eradication. Probiotics after NAA may increase the decolonization rate, hence deserving further study.