Intestinal decolonization of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBL): a retrospective observational study in patients at risk for infection and a brief review of the literature

A Simple In Vitro Test to Select Stools for Fecal Microbiota Transplantation to Limit Intestinal Carriage of Extensively Drug-Resistant Bacteria

Treatment options for multidrug-resistant bacterial infections are limited and often ineffective. Fecal microbiota transplantation (FMT) has emerged as a promising therapy for intestinal multidrug-resistant bacterial decolonization. However, clinical results are discrepant. The aim of our pilot study was to evaluate the screening performance of a simple diagnostic tool to select fecal samples that will be effective in decolonizing the intestine. Fecal samples from 10 healthy subjects were selected. We developed an agar spot test to evaluate their antagonistic activity toward the growth of VanA Enterococcus faecium and OXA-48-producing Klebsiella pneumoniae, two of the most serious and urgent threats of antibiotic resistance. Most fecal samples were able to limit the growth of both bacteria in vitro but with large inter-individual variation. The samples with the highest and lowest antagonistic activity were used for FMT in a mouse model of intestinal colonization. FMT was not successful in reducing intestinal colonization with VanA Enterococcus faecium, whereas FMT performed with the fecal sample showing the highest activity on the agar spot test was able to significantly reduce the intestinal colonization of mice with Klebsiella pneumoniae OXA-48. The agar spot test could thus serve as a reliable screening tool to select stool samples with the best potential to eradicate/reduce multidrug-resistant bacteria carriage after FMT.

Decolonizing drug-resistant E. coli with phage and probiotics: breaking the frequency-dependent dominance of residents

Widespread antibiotic resistance in commensal bacteria creates a persistent challenge for human health. Resident drug-resistant microbes can prevent clinical interventions, colonize wounds post-surgery, pass resistance traits to pathogens or move to more harmful niches following routine interventions such as catheterization. Accelerating the removal of resistant bacteria or actively decolonizing particular lineages from hosts could therefore have a number of long-term benefits. However, removing resident bacteria via competition with probiotics, for example, poses a number of ecological challenges. Resident microbes are likely to have physiological and numerical advantages and competition based on bacteriocins or other secreted antagonists is expected to give advantages to the dominant partner, via positive frequency dependence. Since a narrow range of Escherichia coli genotypes (primarily those belonging to the clonal group ST131) cause a significant proportion of multidrug-resistant infections, this group presents a promising target for decolonization with bacteriophage, as narrow-host-range viral predation could lead to selective removal of particular genotypes. In this study we tested how a combination of an ST131-specific phage and competition from the well-known probiotic E. coli Nissle strain could displace E. coli ST131 under aerobic and anaerobic growth conditions in vitro. We showed that the addition of phage was able to break the frequency-dependent advantage of a numerically dominant ST131 isolate. Moreover, the addition of competing E. coli Nissle could improve the ability of phage to suppress ST131 by two orders of magnitude. Low-cost phage resistance evolved readily in these experiments and was not inhibited by the presence of a probiotic competitor. Nevertheless, combinations of phage and probiotic produced stable long-term suppression of ST131 over multiple transfers and under both aerobic and anaerobic growth conditions. Combinations of phage and probiotic therefore have real potential for accelerating the removal of drug-resistant commensal targets.

Comparing the efficacy of different methods of faecal microbiota transplantation via oral capsule, oesophagogastroduodenoscopy, colonoscopy, or gastric tube

BACKGROUND

The increasing prevalence of multidrug-resistant organism (MDRO) carriage poses major challenges to medicine as healthcare costs increase. Recently, faecal microbiota transplantation (FMT) has been discussed as a novel and effective method for decolonizing MDRO.

AIM

To compare the efficacy of different FMT methods to optimize the success rate of decolonization in patients with MDRO carriage.

METHODS

This prospective cohort study enrolled patients with MDRO carriages from 2018 to 2021. Patients underwent FMT via one of the following methods: oral capsule, oesophagogastroduodenoscopy (EGD), colonoscopy, or gastric tube.

FINDINGS

A total of 57 patients underwent FMT for MDRO decolonization. The colonoscopy group required the shortest time for decolonization, whereas the EGD group required the longest (24.9 vs 190.4 days, P = 0.022). The decolonization rate in the oral capsule group was comparable to that in the EGD group (84.6% vs 85.7%, P = 0.730). An important clinical factor associated with decolonization failure was antibiotic use after FMT (odds ratio = 6.810, P = 0.008). All four groups showed reduced proportions of MDRO species in microbiome analysis after FMT.

CONCLUSION

Compared to other conventional methods, the oral capsule is an effective FMT method for patients who can tolerate an oral diet. The discontinuation of antibiotics after FMT is a key factor in the success of decolonization.

Antibiotic resistance and the alternatives to conventional antibiotics: The role of probiotics and microbiota in combating antimicrobial resistance

From the introduction of the first antibiotic to the present day, the emergence of antibiotic resistance has been a difficult problem for medicine. Regardless of the type of antibiotic resistance, the presence of resistant isolates in clinical and even asymptomatic fecal carriers becomes a difficult public health problem. Therefore, the use of new antimicrobial combination therapies or alternative agents with antimicrobial activity that have the least side effects, including plant-, metal-, and nanoparticle-based agents, could be crucial and useful. Recently, the use of probiotics as a hypothetical candidate to combat infectious disease control and antimicrobial resistance has received notable attention. Considering the alteration of the microbiota in fecal carriers and also in patients with resistant bacterial isolates, the use of probiotics could have an appropriate effect on the balance of the microbial population. In this review, we have attempted to discuss the history of antimicrobial resistance and provide an overview of microbiota change and the use of probiotics as new agents with antimicrobial activity associated with the emergence of resistant isolates.

The Clinical Importance of Preoperative Rectal Swabs in Patients after Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

Background

Surgical site infections are among the most common healthcare-associated infections, especially in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). The aim of this retrospective study was to examine postoperative infectious complications according to preoperative screening findings of nasal and rectal swabs.

Methods

Two hundred four consecutive patients received nasal and rectal swab examination for multidrug-resistant (MDR) bacteria within 30 days before the operation in patients where CRS and HIPEC were planned. Inclusion criteria were as follows: confirmed peritoneal metastases (histologically and/or cytologically); age under 85 years; adequate renal, liver, and bone marrow function; no sign of infection preoperatively; resectable disease; and CRS and HIPEC procedure. If surgical site infection occurred, the microbial spectrum of the site was assessed. One hundred twenty-one patients (63 female [52.1%] and 58 male [47.9%]) met the criteria and were further analyzed retrospectively. Statistical correlations between postoperative complications and risk factors were investigated by univariate and multivariate analysis.

Results

Postoperative complications in total were observed in 57 patients (47.1%) with major complications (Clavien-Dindo grades 3-4) in 15 patients (12.4%) and infectious complications in 37 (30.6%) patients. The overall prevalence of nasal MRSA carriage was 3.28%, and the overall prevalence of rectal MDR bacteria carriage was 10.7%. In propensity score analysis, colonized patients compared to noncolonized patients showed increased total complications (CD1-5, p = 0.025), infectious complications (p = 0.028), surgical site infections (p = 0.022) as well as pneumonia (p = 0.016). Multivariate analysis showed that in addition to preoperative rectal colonization, American Society of Anesthesiologists score was a risk factor for postoperative complications.

Conclusions

Preoperative 3-MRGN and vancomycin-resistant enterococcus colonization were associated with increased complications and surgical site infections. Special antimicrobial treatment pathways are necessary for these patients to reduce postoperative complications due to colonization.

An animal model of limitation of gut colonization by carbapenemase-producing Klebsiella pneumoniae using rifaximin

Current knowledge suggests that infection by carbapenem-resistant enterobacteria is preceded by gut colonization. It is hypothesized that colonization is eradicated by non-absorbable antibiotics like rifaximin. We investigated the effect of rifaximin against carbapenem-resistant Klebsiella pneumoniae (CRKP) in vitro and in a mouse model. We studied the in vitro efficacy of rifaximin against 257 CRKP clinical isolates, 188 KPC producers and 69 OXA-48 producers, by minimum inhibitory concentration and time-kill assays. We then developed a model of gut colonization by feeding 30 C57Bl6 mice with 10⁸ cfu of one KPC-KP isolate for 7 days; mice were pre-treated orally with saline, omeprazole or ampicillin. Then, another 60 mice with established KPC-2 gut colonization received orally for 7 consecutive days rifaximin 180 mg/kg dissolved in ethanol and 4% bile or vehicle. On days 0, 3 and 7 stool samples were collected; mice were sacrificed for determination of tissue outgrowth. At a concentration of 1000 μg/ml rifaximin inhibited 84.8% of CRKP isolates. Α 3 × log₁₀ decrease of the starting inoculum was achieved by 100, 250 and 500 μg/ml of rifaximin after 24 h against 25, 55 and 55% of isolates. Pre-treatment with ampicillin was necessary for gut colonization by KPC-KP. Treatment with rifaximin succeeded in reducing KPC-KP load in stool and in the intestine. Rifaximin inhibits at clinically meaningful gut concentrations the majority of CRKP isolates and is efficient against gut colonization by KPC-KP.

Consequences of Extended Spectrum Beta-Lactamase-Producing Enterobacteriaceae and Methicillin-Resistant Staphylococcus aureus Carriage in Awaiting Liver Transplant Patients

Infections in patients with cirrhosis are associated with liver-related complications (LRCs), especially in patients awaiting liver transplantation (LT). The aim of this study was to evaluate the impact of methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum beta-lactamase colonization on infections and LRCs for patients on the wait list and on infections after LT. We retrospectively included 250 of 483 patients with cirrhosis who were placed on the wait list for LT from December 2015 to January 2018. These patients were screened for MRSA or extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBLE) at the time of wait-list placement and after LT. Of the patients, 76% were male with a mean age of 57.5 ± 10 years, and the most frequent cause of liver disease was alcohol (39%). Median Model for End-Stage Liver Disease (MELD) score was 19 (12-28). Only 1 patient was positive for MRSA; 19% of patients (n = 47) had ESBLE fecal carriage at the time of wait-list placement and 15% (n = 37) had it after LT. Infection-free survival on the wait list and after LT, according to fecal carriage status, was not statistically different between 2 groups. LRC-free survival at 6 and 12 months was significantly lower in ESBLE fecal carriage (HR, 1.6; P = 0.04). MELD score >19 (HR, 3.0; P = 0.01) and occurrence of infection during the first 3 months on the wait list (HR, 4.13; P < 0.001) were independent risk factors for LRC occurrence in the multivariate analysis. Our study is the first showing that in a cohort of patients with cirrhosis waiting for LT LRC-free survival was lower in patients with ESBLE fecal carriage but that infection-free survival was not different between the 2 groups.

A mathematical model and inference method for bacterial colonization in hospital units applied to active surveillance data for carbapenem-resistant enterobacteriaceae

Widespread use of antibiotics has resulted in an increase in antimicrobial-resistant microorganisms. Although not all bacterial contact results in infection, patients can become asymptomatically colonized, increasing the risk of infection and pathogen transmission. Consequently, many institutions have begun active surveillance, but in non-research settings, the resulting data are often incomplete and may include non-random testing, making conventional epidemiological analysis problematic. We describe a mathematical model and inference method for in-hospital bacterial colonization and transmission of carbapenem-resistant Enterobacteriaceae that is tailored for analysis of active surveillance data with incomplete observations. The model and inference method make use of the full detailed state of the hospital unit, which takes into account the colonization status of each individual in the unit and not only the number of colonized patients at any given time. The inference method computes the exact likelihood of all possible histories consistent with partial observations (despite the exponential increase in possible states that can make likelihood calculation intractable for large hospital units), includes techniques to improve computational efficiency, is tested by computer simulation, and is applied to active surveillance data from a 13-bed rehabilitation unit in New York City. The inference method for exact likelihood calculation is applicable to other Markov models incorporating incomplete observations. The parameters that we identify are the patient-patient transmission rate, pre-existing colonization probability, and prior-to-new-patient transmission probability. Besides identifying the parameters, we predict the effects on the total prevalence (0.07 of the total colonized patient-days) of changing the parameters and estimate the increase in total prevalence attributable to patient-patient transmission (0.02) above the baseline pre-existing colonization (0.05). Simulations with a colonized versus uncolonized long-stay patient had 44% higher total prevalence, suggesting that the long-stay patient may have been a reservoir of transmission. High-priority interventions may include isolation of incoming colonized patients and repeated screening of long-stay patients.

Controlling intestinal colonization of high-risk haematology patients with ESBL-producing Enterobacteriaceae: a randomized, placebo-controlled, multicentre, Phase II trial (CLEAR)

OBJECTIVES

We assessed the efficacy and safety of an oral antimicrobial regimen for short- and long-term intestinal eradication of ESBL-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EC/KP) in immunocompromised patients.

METHODS

We performed a randomized (2:1), double-blind multicentre Phase II study in four haematology-oncology departments. Patients colonized with ESBL-EC/KP received a 7 day antimicrobial regimen of oral colistin (2 × 106 IU 4×/day), gentamicin (80 mg 4×/day) and fosfomycin (three administrations of 3 g every 72 h), or placebo. Faecal, throat and urine specimens were collected on day 0, 6 ± 2, 11 ± 2, 28 ± 4 and 42 ± 4 after treatment initiation, and the quantitative burden of ESBL-EC/KP, resistance genes and changes in intestinal microbiota were analysed. Clinicaltrials.gov: NCT01931592.

RESULTS

As the manufacture of colistin powder was suspended worldwide, the study was terminated prematurely. Overall, 29 (18 verum/11 placebo) out of 47 patients were enrolled. The short-term intestinal eradication was marginal at day 6 (verum group 15/18, 83.3% versus placebo 2/11, 18.2%; relative risk 4.58, 95% CI 1.29-16.33; Fisher's exact test P = 0.001) and not evident at later timepoints. Quantitative analysis showed a significant decrease of intestinal ESBL-EC/KP burden on day 6. Sustained intestinal eradication (day 28 + 42) was not achieved (verum, 38.9% versus placebo, 27.3%; P = 0.299). In the verum group, mcr-1 genes were detected in two faecal samples collected after treatment. Microbiome analysis showed a significant decrease in alpha diversity and a shift in beta diversity.

CONCLUSIONS

In this prematurely terminated study of a 7 day oral antimicrobial eradication regimen, short-term ESBL-EC/KP suppression was marginal, while an altered intestinal microbiota composition was clearly apparent.

Investigating the use of bacteriophages as a new decolonization strategy for intestinal carriage of CTX-M-15-producing ST131 Escherichia coli: An in vitro continuous culture system model

OBJECTIVES

We investigated the use of bacteriophages as a strategy to decolonize intestinal carriers of multidrug-resistant Escherichia coli.

METHODS

A fermentor was used as a continuous culture system for 48h. Two different pools of faeces (studies I and II) obtained from volunteers were spiked with a CTX-M-15-producing ST131 E. coli (strain 4901.28) susceptible to bacteriophages and challenged with three doses of INTESTI Bacteriophage cocktail administered at 2, 6 and 10h after the inoculum. Bacterial typing was performed by implementing microdilution panels, spot test, rep-PCR and whole-genome sequencing (including cgMLST and single-nucleotide variant analysis) obtained using Nanopore and Illumina platforms.

RESULTS

In study I, bacteriophages decreased the numbers of 4901.28 dramatically (≤10¹CFU/mL after 6h). In contrast, during study II, a phage-resistant mutant of 4901.28 persisted in the continuous culture (10⁴CFU/mL at 48h). Whole-genome sequencing revealed the presence of two additional plasmids in the mutant as well as 11 single-nucleotide variants, including one chromosomal in a glycosyltransferase family 2 protein that is responsible for the transfer of sugars to polysaccharides and lipids. In both studies, the commensal E. coli population remained unchanged by the phage treatment maintaining itself at 10⁸CFU/mL.

CONCLUSIONS

Our data indicates that bacteriophage cocktails may be implemented to decolonize some intestinal carriers. However, the individual microbiota composition may have an impact on the development of phage resistance. Mechanisms underlying this phenomenon are likely to be various and complex. Further in vivo studies and protein expression experiments are needed to confirm our observations and hypotheses.

Metagenomic Characterization of Gut Microbiota of Carriers of Extended-Spectrum Beta-Lactamase or Carbapenemase-Producing Enterobacteriaceae Following Treatment with Oral Antibiotics and Fecal Microbiota Transplantation: Results from a Multicenter Randomized Trial

Background: The R-GNOSIS (Resistance in Gram-Negative Organisms: Studying Intervention Strategies) WP3 study was the first multicenter randomized clinical trial systematically investigating fecal microbiota transplantation (FMT) for intestinal decolonization of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) or carbapenemase-producing Enterobacteriaceae (CPE). Here, we characterized the temporal dynamics of fecal microbiota changes in a sub-cohort of the R-GNOSIS WP3 participants before and after antibiotics/FMT using whole metagenome shotgun sequencing. Methods: We sequenced fecal DNA obtained from 16 ESBL-E/CPE carriers having received oral colistin/neomycin followed by FMT and their corresponding seven donors. Ten treatment-naïve controls from the same trial were included. Fecal samples were collected at baseline (V0), after antibiotics but before FMT (V2) and three times after FMT (V3, V4 and V5). Results: Antibiotic treatment transiently decreased species richness and diversity and increased the abundance of antibiotic resistance determinants (ARDs). Bifidobacterium species, together with butyrate- and propionate-producing species from Lachnospiraceae and Ruminococcaceae families were significantly enriched in post-FMT microbiota of treated carriers. After FMT, the proportion of Enterobacteriaceae was lower compared to baseline but without statistical significance. Conclusions: Combined antibiotic and FMT treatment resulted in enrichment of species that are likely to limit the gut colonization by ESBL-E/CPE.

Detection of High-Level Rifaximin Resistance in Enteric Bacteria by Agar Screen

Objectives: This study aimed at determining the prevalence of rifaximin resistance in a large collection of Enterobacterales resistant to third-generation cephalosporins. A simple agar screen was developed to detect high-level resistance. Methods: A total of 401 isolates nonsusceptible to third-generation cephalosporins (including 342 Escherichia coli and 39 Klebsiella spp. and 20 Enterobacter spp.) were tested by microdilution for their MICs of rifaximin and rifampicin. Isolates with a confirmed rifaximin minimal inhibitory concentration (MIC) of >64 mg/L and a number of high-level resistant, and susceptible control isolates were tested for growth on Mueller-Hinton agar supplemented with rifaximin or rifampicin at a concentration of 256 mg/L. Amino acid mutations in rpoB and the presence of rifaximin resistance-associated genes arabidopsis response regulator (arr) 2/3 were investigated. Results: Microdilution assays identified rifaximin resistance in nine E. coli and three Klebsiella spp. isolates with complete cross-resistance to rifampicin (MICs of both >64 mg/L). The rifaximin agar screen correctly identified 9/9 clinical E. coli isolates, 2/2 E. coli controls, and 3/3 Klebsiella spp. with high-level rifaximin resistance, and was negative in 45 control clinical isolates with rifaximin MICs ranging between 2 and 32 mg/L according to broth microdilution. All nine high-level rifaximin agar screen-positive E. coli clinical isolates (vs. none of the tested controls) had rpoB mutations or carried arr2/3. Conclusions: Our agar screen test has the potential to detect high-level rifaximin-resistant Enterobacterales. Such strains remain rare among extended spectrum beta-lactamase (ESBL)-positive enteric bacteria, but may emerge among patients receiving rifaximin for prevention of hepatic encephalopathy and spontaneous bacterial peritonitis or among patients receiving rifaximin for other indications.

Probiotics for intestinal decolonization of ESBL-producing Enterobacteriaceae: a randomized, placebo-controlled clinical trial

OBJECTIVES

Infections with extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (EPE) are a major healthcare concern. Our goal was to investigate whether a probiotic mixture could be used for eradication therapy in patients with prolonged intestinal EPE carriage.

METHODS

We performed a randomized, placebo-controlled, single-blinded clinical superiority trial in the south of Sweden between February 2017 and April 2019. Probiotic Vivomixx®, a mixture of 8 different living bacterial strains or placebo was given to adult outpatients intestinally colonized for at least 3 months with EPE. Patients with suspected active infections at the time of evaluation were excluded, and also those with immunosuppression, severe psychiatric disorder, drug abuse or dementia. Each patient in the probiotic arm was administered 2 sachets (9.0 × 10¹¹ live bacteria) twice daily for 2 months. The primary outcome was intestinal EPE eradication at the end of the 1-year follow-up, as shown by 3 consecutive negative EPE rectal swabs during the follow-up year. The per protocol follow-up for all patients was 1, 3, 6 and 12 months after the initiation of the intervention. ClinicalTrials.gov Identifier: NCT03860415.

RESULTS

In total, the target size of 80 patients were included. The median age was 68 years in both groups. The number of females in the probiotics group was 23 (58%) and in the placebo group 28 (70%). At the end of the trial, 12.5% (5 out of 40) of the patients in the probiotic group had achieved successful eradication of EPE, as defined by the primary outcome, in the intention to treat analysis. In the placebo group, 5% (2 out of 40) of the patients had achieved successful eradication of EPE (odds ratio 2.71; 95% confidence interval (CI), 0.49-14.9; p 0.24).

CONCLUSIONS

Successful EPE eradication was observed in very few individuals. This trial did not support Vivomixx® as being superior to placebo for intestinal decolonization in adult patients with chronic colonization of EPE, but was limited in power.

Antimicrobial resistance in nephrology

The prevalence of antimicrobial resistance among many common bacterial pathogens is increasing. The emergence and global dissemination of these antibiotic-resistant bacteria (ARB) is fuelled by antibiotic selection pressure, inter-organism transmission of resistance determinants, suboptimal infection prevention practices and increasing ease and frequency of international travel, among other factors. Patients with chronic kidney disease, particularly those with end-stage renal disease who require dialysis and/or kidney transplantation, have some of the highest rates of colonization and infection with ARB worldwide. These ARB include methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp. and several multidrug-resistant Gram-negative organisms. Antimicrobial resistance limits treatment options and increases the risk of infection-related morbidity and mortality. Several new antibiotic agents with activity against some of the most common ARB have been developed, but resistance to these agents is already emerging and highlights the dire need for new treatment options as well as consistent implementation and improvement of basic infection prevention practices. Clinicians involved in the care of patients with renal disease must be familiar with the local epidemiology of ARB, remain vigilant for the emergence of novel resistance patterns and adhere strictly to practices proven to prevent transmission of ARB and other pathogens.

Strategies for the eradication of extended-spectrum beta-lactamase or carbapenemase-producing Enterobacteriaceae intestinal carriage

Introduction: Among the multidrug resistant pathogens, extended-spectrum beta-lactamase (ESBL-E) or carbapenemase-producing Enterobacteriaceae (CPE) are currently considered the main threat due to the scarcity of therapeutic options and their rapid spread around the globe. In addition to developing new antibiotics and stopping transmission, recent research has focused on 'decolonization' strategies to eradicate the carriage of ESBL-E/CPE before infection occurs. Areas covered: In this narrative review, we aim to describe the current evidence of decolonization strategies for ESBL-E or CPE intestinal carriage. We first define decolonization and highlight the issues related to the lack of standardized definitions, then we summarize the available data on the natural history of colonization. Finally, we review the strategies assessed over the past 10 years for ESBL and CPE decolonization: oral antibiotics, probiotics and more recently fecal microbiota transplantation. We conclude by presenting the risks and uncertainties associated with these strategies. Expert opinion: The evidence available today is too low to recommend decolonization strategies for ESBL-E or CPE in routine clinical practice. The potential increase of resistance and the impact of microbiome manipulation should not be underestimated. Some of these decolonization strategies may nevertheless be effective, at least in temporarily suppressing colonization, which could be useful for specific populations such as high-risk patients. Effectiveness and long-term effects must be properly assessed through well-designed randomized controlled trials.

Gut Microbiota Modulation for Multidrug-Resistant Organism Decolonization: Present and Future Perspectives

The emergence of antimicrobial resistance (AMR) is of great concern to global public health. Treatment of multi-drug resistant (MDR) infections is a major clinical challenge: the increase in antibiotic resistance leads to a greater risk of therapeutic failure, relapses, longer hospitalizations, and worse clinical outcomes. Currently, there are no validated treatments for many MDR or pandrug-resistant (PDR) infections, and preventing the spread of these pathogens through hospital infection control procedures and antimicrobial stewardship programs is often the only tool available to healthcare providers. Therefore, new solutions to control the colonization of MDR pathogens are urgently needed. In this narrative review, we discuss current knowledge of microbiota-mediated mechanisms of AMR and strategies for MDR colonization control. We focus particularly on fecal microbiota transplantation for MDR intestinal decolonization and report updated literature on its current clinical use.

Faecal microbiota transplantation for eradicating carriage of multidrug-resistant organisms: a systematic review

BACKGROUND

Multidrug-resistant (MDR) microorganism development in the gut is frequently the result of inappropriate antibiotic use. Faecal microbiota transplantation (FMT) restores normal gut microbiota in patients with Clostridium difficile infection. We hypothesized that it may help in decolonizing MDR organisms (MDROs) and in preventing recurrent MDR infections.

OBJECTIVES

To assess FMT efficacy (eradication rate) for decolonizing MDROs and preventing recurrent MDR infections.

DATA SOURCES

Medline, Embase and Web of Science (inception through 11 February 2019).

STUDY ELIGIBILITY CRITERIA

Clinical trials, retrospective studies, case reports and case series.

PARTICIPANTS

Patients with MDR infections or MDRO colonization treated with FMT.

INTERVENTIONS

FMT.

METHODS

Systematic review.

RESULTS

Twenty-one studies (one randomized clinical trial, seven uncontrolled clinical trials, two retrospective cohort studies, two case series, nine case reports) assessing 192 patients were included. Three studies assessed FMT efficacy in preventing MDR infections; 16 assessed its effect on MDRO colonization; two assessed both. Data from 151 patients were included in the final analyses. In studies with low to moderate risk of bias, the eradication rate was 37.5% to 87.5%. Efficacy was similar in studies looking at infection or colonization and did not differ by length of follow-up. No serious adverse events from FMT were reported. Seven patients died of other causes.

CONCLUSIONS

FMT could be used as a treatment for eradicating MDR colonization and possibly preventing recurrent MDR infections, once more supporting efficacy and safety data are available. Larger well-designed randomized controlled trials are needed to further explore this therapy.

Faecal microbiota transplantation for the decolonization of antibiotic-resistant bacteria in the gut: a systematic review and meta-analysis

Antibiotic resistance is a growing global problem associated with increased morbidity and mortality, and presents a significant financial and economic burden on healthcare. Faecal microbiota transplantation (FMT) has been proven effective for curing recurrent Clostridium difficile infections, however no systematic review to date has addressed its effectiveness for decolonization of antibiotic-resistant bacteria from the gut. The aim of this study was to establish whether faecal microbiota transplantation decolonizes antibiotic-resistant bacteria from the gut of colonized adults. A systematic review was performed by undertaking a comprehensive search on MEDLINE, Embase, CENTRAL, PubMed and CINAHL databases for evidence up until May 2018. Randomized and non-randomized studies evaluating the effects of FMT on gut colonization of antibiotic-resistant bacteria in adults were eligible. Studies were assessed using the Joanna Briggs Institution critical appraisal checklists. Quality of reporting was assessed using PROCESS and CARE checklists. Data was synthesized narratively, along with a meta-analysis of proportions for the primary outcome. Five studies with a total number of 52 participants were included. Evidence of low quality showed that decolonization was achieved in half of the cases one month after FMT with higher response noted in Pseudomonas aeruginosa, and lower response in Klebsiella pneumoniae with New Delhi metallo-beta-lactamase 1 (NDM-1) and extended-spectrum β-lactamase (ESBL) mechanisms of resistance. In successful cases, 70% of decolonization cases occurred within the first week after FMT. Few temporary adverse events were identified. Despite the limitations of the included studies, evidence from this review indicates a potential benefit of FMT as a decolonization intervention, which can only be confirmed by future well-designed RCTs.

ESCMID-EUCIC clinical guidelines on decolonization of multidrug-resistant Gram-negative bacteria carriers

SCOPE

The aim of these guidelines is to provide recommendations for decolonizing regimens targeting multidrug-resistant Gram-negative bacteria (MDR-GNB) carriers in all settings.

METHODS

These evidence-based guidelines were produced after a systematic review of published studies on decolonization interventions targeting the following MDR-GNB: third-generation cephalosporin-resistant Enterobacteriaceae (3GCephRE), carbapenem-resistant Enterobacteriaceae (CRE), aminoglycoside-resistant Enterobacteriaceae (AGRE), fluoroquinolone-resistant Enterobacteriaceae (FQRE), extremely drug-resistant Pseudomonas aeruginosa (XDRPA), carbapenem-resistant Acinetobacter baumannii (CRAB), cotrimoxazole-resistant Stenotrophomonas maltophilia (CRSM), colistin-resistant Gram-negative organisms (CoRGNB), and pan-drug-resistant Gram-negative organisms (PDRGNB). The recommendations are grouped by MDR-GNB species. Faecal microbiota transplantation has been discussed separately. Four types of outcomes were evaluated for each target MDR-GNB:(a) microbiological outcomes (carriage and eradication rates) at treatment end and at specific post-treatment time-points; (b) clinical outcomes (attributable and all-cause mortality and infection incidence) at the same time-points and length of hospital stay; (c) epidemiological outcomes (acquisition incidence, transmission and outbreaks); and (d) adverse events of decolonization (including resistance development). The level of evidence for and strength of each recommendation were defined according to the GRADE approach. Consensus of a multidisciplinary expert panel was reached through a nominal-group technique for the final list of recommendations.

RECOMMENDATIONS

The panel does not recommend routine decolonization of 3GCephRE and CRE carriers. Evidence is currently insufficient to provide recommendations for or against any intervention in patients colonized with AGRE, CoRGNB, CRAB, CRSM, FQRE, PDRGNB and XDRPA. On the basis of the limited evidence of increased risk of CRE infections in immunocompromised carriers, the panel suggests designing high-quality prospective clinical studies to assess the risk of CRE infections in immunocompromised patients. These trials should include monitoring of development of resistance to decolonizing agents during treatment using stool cultures and antimicrobial susceptibility results according to the EUCAST clinical breakpoints.

A 5-day course of oral antibiotics followed by faecal transplantation to eradicate carriage of multidrug-resistant Enterobacteriaceae: a randomized clinical trial

OBJECTIVES

Intestinal carriage with extended spectrum β-lactamase Enterobacteriaceae (ESBL-E) and carbapenemase-producing Enterobacteriaceae (CPE) can persist for months. We aimed to evaluate whether oral antibiotics followed by faecal microbiota transplantation (FMT) can eradicate intestinal carriage with ESBL-E/CPE.

METHODS

Randomized, open-label, superiority trial in four tertiary-care centres (Geneva (G), Paris (P), Utrecht (U), Tel Aviv (T)). Non-immunocompromised adult patients were randomized 1: 1 to either no intervention (control) or a 5-day course of oral antibiotics (colistin sulphate 2 × 10⁶ IU 4×/day; neomycin sulphate 500 mg 4×/day) followed by frozen FMT obtained from unrelated healthy donors. The primary outcome was detectable intestinal carriage of ESBL-E/CPE by stool culture 35-48 days after randomization (V4). ClinicalTrials.govNCT02472600. The trial was funded by the European Commission (FP7).

RESULTS

Thirty-nine patients (G = 14; P = 16; U = 7; T = 2) colonized by ESBL-E (n = 36) and/or CPE (n = 11) were enrolled between February 2016 and June 2017. In the intention-to-treat analysis 9/22 (41%) patients assigned to the intervention arm were negative for ESBL-E/CPE at V4 (1/22 not receiving the intervention imputed as positive) whereas in the control arm 5/17 (29%) patients were negative (one lost to follow up imputed as negative) resulting in an OR for decolonization success of 1.7 (95% CI 0.4-6.4). Study drugs were well tolerated overall but three patients in the intervention group prematurely stopped the study antibiotics because of diarrhoea (all received FMT).

CONCLUSIONS

Non-absorbable antibiotics followed by FMT slightly decreased ESBL-E/CPE carriage compared with controls; this difference was not statistically significant, potentially due to early trial termination. Further clinical investigations seem warranted.

Impact of Amoxicillin-Clavulanate followed by Autologous Fecal Microbiota Transplantation on Fecal Microbiome Structure and Metabolic Potential

The spread of multidrug resistance among pathogenic organisms threatens the efficacy of antimicrobial treatment options. The human gut serves as a reservoir for many drug-resistant organisms and their resistance genes, and perturbation of the gut microbiome by antimicrobial exposure can open metabolic niches to resistant pathogens. Once established in the gut, antimicrobial-resistant bacteria can persist even after antimicrobial exposure ceases. Strategies to prevent multidrug-resistant organism (MDRO) infections are scarce, but autologous fecal microbiota transplantation (autoFMT) may limit gastrointestinal MDRO expansion. AutoFMT involves banking one’s feces during a healthy state for later use in restoring gut microbiota following perturbation. This pilot study evaluated the effect of amoxicillin-clavulanic acid (Amox-Clav) exposure and autoFMT on gastrointestinal microbiome taxonomic composition, resistance gene content, and metabolic capacity. Importantly, we found that metabolic capacity was perturbed even in cases where gross phylogeny remained unchanged and that autoFMT was safe and well tolerated.

Strategies to prevent multidrug-resistant organism (MDRO) infections are scarce, but autologous fecal microbiota transplantation (autoFMT) may limit gastrointestinal MDRO expansion. AutoFMT involves banking one’s feces during a healthy state for later use in restoring gut microbiota following perturbation. This pilot study evaluated the effect of autoFMT on gastrointestinal microbiome taxonomic composition, resistance gene content, and metabolic capacity after exposure to amoxicillin-clavulanic acid (Amox-Clav). Ten healthy participants were enrolled. All received 5 days of Amox-Clav. Half were randomized to autoFMT, derived from stool collected pre-antimicrobial exposure, by enema, and half to saline enema. Participants submitted stool samples pre- and post-Amox-Clav and enema and during a 90-day follow-up period. Shotgun metagenomic sequencing revealed taxonomic composition, resistance gene content, and metabolic capacity. Amox-Clav significantly altered gut taxonomic composition in all participants (n = 10, P < 0.01); however, only three participants exhibited major changes at the phylum level following exposure. In the cohort as a whole, beta-lactamase genes were enriched following Amox-Clav (P < 0.05), and predicted metabolic capacity was significantly altered (P < 0.01). Species composition, metabolic capacity, and beta-lactamase abundance returned to pre-antimicrobial exposure state 7 days after either autoFMT or saline enema (P > 0.05, compared to enrollment). Alterations to microbial metabolic capacity occurred following antimicrobial exposure even in participants without substantial taxonomic disruption, potentially creating open niches for pathogen colonization. Our findings suggest that metabolic potential is an important consideration for complete assessment of antimicrobial impact on the microbiome. AutoFMT was well tolerated and may have contributed to phylogenetic recovery. (This study has been registered at ClinicalTrials.gov under identifier NCT02046525.)

IMPORTANCE The spread of multidrug resistance among pathogenic organisms threatens the efficacy of antimicrobial treatment options. The human gut serves as a reservoir for many drug-resistant organisms and their resistance genes, and perturbation of the gut microbiome by antimicrobial exposure can open metabolic niches to resistant pathogens. Once established in the gut, antimicrobial-resistant bacteria can persist even after antimicrobial exposure ceases. Strategies to prevent multidrug-resistant organism (MDRO) infections are scarce, but autologous fecal microbiota transplantation (autoFMT) may limit gastrointestinal MDRO expansion. AutoFMT involves banking one’s feces during a healthy state for later use in restoring gut microbiota following perturbation. This pilot study evaluated the effect of amoxicillin-clavulanic acid (Amox-Clav) exposure and autoFMT on gastrointestinal microbiome taxonomic composition, resistance gene content, and metabolic capacity. Importantly, we found that metabolic capacity was perturbed even in cases where gross phylogeny remained unchanged and that autoFMT was safe and well tolerated.

Hyperimmune bovine colostrum reduces gastrointestinal carriage of uropathogenic Escherichia coli

Debilitating recurrent urinary tract infections (UTIs) are often associated with gastrointestinal colonisation by uropathogens, such as uropathogenic Escherichia coli (UPEC), suggesting that these populations might be a suitable target for the treatment and prevention of recurrent UTI. However, antimicrobial treatment is generally unable to prevent recurrent UTI, and often selects for multidrug resistant uropathogens in the gut, and causes dysbiosis of the gut, vaginal, and urinary microbiota. Of note, the globally-disseminated multi drug resistant UPEC lineage, ST131, is known to both persistently colonise the gut and the urinary tract, and is associated with antibiotic treatment failure, indicating the need for novel non-antibiotic therapeutics for the treatment of UTI. This study therefore presents hyperimmune bovine colostrum (HBC) as a suitable therapy for the treatment of UPEC gastrointestinal colonisation. This work demonstrates that the vaccination of pregnant cows with inactivated cells from a ST131 UPEC isolate results in a highly specific anti-UPEC HBC, and that this product is able to disrupt the gastrointestinal colonisation of ST131 UPEC in mice.

Decolonization of Intestinal Carriage of MDR/XDR Gram-Negative Bacteria with Oral Colistin in Patients with Hematological Malignancies: Results of a Randomized Controlled Trial

Background

Intestinal colonization by MDR/XDR gram-negative bacteria leads to an increased risk of subsequent bloodstream infections (BSI) in patients receiving chemotherapy as a treatment for hematologic malignancies.

Objectives

The objective of this study was to evaluate the efficacy of oral colistin in eradicating the intestinal carriage of MDR/XDR Gram-negative bacteria in patients with hematological malignancies.

Methods

In a tertiary hematology center, adult patients with intestinal colonization by MDR/XDR Gram-negative bacteria were included in a randomized controlled trial (RCT) during a period from November 2016 to October 2017. Patients were treated with oral colistin for 14 days or observed with the primary outcome set as decolonization on day 21 post-treatment. Secondary outcomes included treatment safety and changes in MICs of isolated microorganisms. ClinicalTrials.gov Identifier: NCT02966457.

Results

Short-time positive effect (61.3% vs 32.3%; OR 3.32; 95% CI 1.17-9.44; p=0.0241) was demonstrated on the day 14 of colistin treatment, without any statistical difference on day 21 post-treatment. The incidence of BSI in decolonization group was lower in the first 30 days after the intervention (3.2% vs. 12.9%), but overall in the 90-day observation period, it did not show any advantages comparing to control group (log-rank test; p=0.4721). No serious adverse effects or increase in resistance to colistin was observed.

Conclusions

This study suggests that in hematological patients the strategy of selective intestinal decolonization by colistin may be beneficial to decrease the rate of MDR/XDR Gram-negative intestinal colonization and the risk of BSI in the short-term period, having no long-term sustainable effects.

Fecal Microbiota Transplantation in Patients With Blood Disorders Inhibits Gut Colonization With Antibiotic-Resistant Bacteria: Results of a Prospective, Single-Center Study

Background

Patients with blood disorders colonized with antibiotic-resistant bacteria (ARB) are prone to systemic infections that are difficult to treat. Reintroduction of commensal bacteria in a murine model of enterococcal colonization of the gut can lead to eradication of enterococci. We hypothesized that fecal microbiota transplantation (FMT) could be used to eradicate ARB in humans.

Methods

Participants colonized with ARB were treated with intraduodenal FMT according to a prospective protocol (NCT02461199). The primary endpoint was complete ARB decolonization at 1 month after FMT. Secondary endpoints included safety assessment and partial ARB decolonization. Microbiome sequencing was performed to investigate the influence of microbial composition of the transplanted material on the outcome of FMT.

Results

Twenty-five FMTs were performed in 20 participants (including 40% who had neutropenia) who were colonized by a median of 2 (range, 1-4) strains of ARB. The primary endpoint was reached in 15/25 (60%) of the FMTs and more frequently in cases in which there was no periprocedural use of antibiotics (79% vs 36%, P < .05). Among participants, 15/20 (75%) experienced complete ARB decolonization. There were no severe adverse events, and partial ARB decolonization was observed in 20/25 (80%) of the FMTs. The microbiota composition analysis revealed higher abundance of Barnesiella spp., Bacteroides, and Butyricimonas and greater bacterial richness in the fecal material, resulting in eradication of Klebsiella pneumoniae compared with nonresponders.

Conclusions

FMT in patients with blood disorders is safe and promotes eradication of ARB from the gastrointestinal tract.

Clinical Trials Registration

NCT02461199.

Fecal microbiota transplantation against intestinal colonization by extended spectrum beta-lactamase producing Enterobacteriaceae: a proof of principle study

OBJECTIVE

Infections with multidrug-resistant microorganisms are associated with increased hospitalization, medication costs and mortality. Based on our fecal microbiota transplantation (FMT) experience for Clostridium difficile infection, we treated 15 patients carrying ESBL-producing Enterobacteriaceae (ESBL-EB) with FMT. Seven patients underwent a second FMT after 4 weeks when ESBL-EB remained, amounting to a total number of 22 transplants. The objective was decolonization of ESBL-EB.

RESULTS

Three out of fifteen (20%) patients were ESBL-negative at 1, 2 and 4 weeks after the first transplant, while six out of 15 (40%) were negative after the second transplant. Comparison of fecal microbiota at baseline and 4 weeks after FMT revealed restoration of microbial diversity after FMT and a microbial shift towards donor composition. Finally, we suggest several possible factors of response to therapy, such as donor-recipient microbiota match and number of FMTs. Therefore, FMT can be an effective treatment in patients carrying ESBL-EB. Response may be determined by microbiota composition and number of FMT procedures. Trial registration ISRCTN ISRCTN48328635 Registered 11 October 2017, retrospectively registered.

Gut colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae may increase disease activity in biologic-naive outpatients with ulcerative colitis: an interim analysis

BACKGROUND

Certain Enterobacteriaceae strains have been associated with the development of ulcerative colitis (UC). Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae are the most commonly found multi-drug-resistant (MDR) bacteria colonizing the gut in UC patients and might trigger a more severe disease activity in UC patients.

OBJECTIVE

The aim of this study was to evaluate whether disease activity is higher in UC patients with gut colonization with ESBL-producing Enterobacteriaceae.

MATERIALS AND METHODS

A cross-sectional, pilot study was carried out in a tertiary medical center in Latvia. Demographic data were collected; UC disease activity and extent were evaluated according to the full Mayo score, Montreal classification, and adapted Truelove and Witt's index. Rectal swabs with fecal biomaterial were collected, ESBL-producing Enterobacteriaceae were isolated, and bacterial plasmid genes responsible for ESBL production, blaCTX-M, blaTEM, and blaSHV, were detected. UC disease activity was compared in patients with and without gut colonization with ESBL-producing Enterobacteriaceae.

RESULTS

A total of 65 patients with UC were included in the initial analysis. Gut colonization with ESBL-producing Enterobacteriaceae was found in seven (11%) patients - mostly Escherichia coli [5 (71%)] containing the blaCTX-M bacterial plasmid gene. Patients with gut colonization with ESBL-producing Enterobacteriaceae had more severe disease compared with patients without gut colonization according to the full Mayo score (5.86 vs. 3.40; P=0.015), Montreal classification (moderate disease vs. clinical remission; P=0.031), and adapted Truelove and Witt's index (moderate disease vs. mild disease; P=0.008).

CONCLUSION

Gut colonization with ESBL-producing Enterobacteriaceae may increase UC disease activity. Further research is needed to analyze the possible confounding factors that could contribute toward this outcome.

Gut Colonization with Carbapenem-resistant Enterobacteriaceae Adversely Impacts the Outcome in Patients with Hematological Malignancies: Results of A Prospective Surveillance Study

BACKGROUND

Gut colonisation with carbapenem-resistant enterobacteriaceae (CRE) is a risk factor for CRE bacteremia and patients with haematological malignancies (HM) are at the highest risk of mortality.

METHODS

We conducted a prospective surveillance study of gut colonisation with CRE and its impact on the outcome of 225 consecutive patients of HM over 28 months.

RESULTS

The median age of the cohort was 46 years, the majority with acute leukaemia. 48 (21%) patients were colonised with CRE on admission (CAD). Another 46 patients were colonised with CRE in the hospital (CIH). The risk factors for CAD and CIH were a diagnosis of acute leukaemia and duration of hospital stay respectively. CRE accounted for 77% of infection-related mortality (IRM). The incidence of CRE bacteremia in CRE positive patients was 18% (17/94), and mortality in those with CRE bacteremia was 100%. IRM was 35.3% in CIH group compared to 10.5% in the CAD group (p=0.0001). IRM was highest in those with acute myeloid leukaemia (AML) and CIH (54.9% p=0.0001). On multivariate analysis, CIH was the most important risk factor for IRM (HR-7.2).

CONCLUSION

Our data demonstrate that a substantial proportion of patients with HM are colonised with CRE without prior hospitalisation, but those with nosocomial colonisation have the highest risk of mortality, particularly in those with AML.

In Vitro Activity of Neomycin, Streptomycin, Paromomycin and Apramycin against Carbapenem-Resistant Enterobacteriaceae Clinical Strains

We determined the in vitro susceptibility of four aminoglycosides, which are not of the 4,6-disubstituted deoxystreptamine (DOS) subclass against a collection of carbapenem-resistant Enterobacteriaceae (CRE). CRE clinical strains (n = 134) were collected from multiple hospitals in China and carried bla_NDM (bla_NDM−1, bla_NDM−5 or bla_NDM−7; n = 66), bla_KPC−2 (n = 62) or bla_IMP−4 (n = 7; including one carrying bla_NDM−1 and bla_IMP−4). MICs of neomycin, paromomycin, streptomycin and apramycin as well as three 4,6-disubstituted DOS aminoglycosides (amikacin, gentamicin and tobramycin) were determined using the broth microdilution with breakpoints defined by the Clinical Laboratory Standards Institute (for amikacin, gentamicin and tobramycin), US Food and Drug Administration (streptomycin), the National Antimicrobial Resistance Monitoring System (apramycin) or la Société Française de Microbiologie (neomycin and paromomycin). Apramycin-resistant strains were subjected to whole genome sequencing using Illumina X10 platform. Among CRE strains, 65.7, 64.9, 79.1, and 95.5% were susceptible to neomycin (MIC₅₀/MIC₉₀, 8/256 μg/ml), paromomycin (4/>256 μg/ml), streptomycin (16/256 μg/ml) and apramycin (4/8 μg/ml), respectively, while only 55.2, 28.4, and 35.1% were susceptible to amikacin (32/>256 μg/ml), gentamicin (128/>256 μg/ml) and tobramycin (64/>256 μg/ml), respectively. Six CRE strains including five Escherichia coli of different sequence types and one Klebsiella pneumoniae were resistant to apramycin and the apramycin-resistant gene aac(3)-IVa was detected in all of these strains. In conclusion, neomycin, paromomycin, streptomycin and apramycin retain activity against most CRE strains. Although none of these non-4,6-disubstituted DOS aminoglycosides are suitable for intravenous use in human at present, these agents warrant further investigations to be used against CRE infections.

Colonization with Multidrug-Resistant Bacteria - On the Efficiency of Local Decolonization Procedures

The effectiveness of a disinfectant-based decolonization strategy for multidrug-resistant bacteria like extended spectrum β-lactamase (ESBL)-positive Gram-negative bacteria with or without additional fluoroquinolon and carbapenem resistance as well as vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus was assessed.

Between 2011 and 2015, 25 patients from Libya, Syria, and the Ukraine with war traumata were treated at the Bundeswehr hospital Hamburg. The patients were heavily colonized and infected with multidrug-resistant bacteria, altogether comprising 371 distinct combinations of pathogens and isolation sites. Local disinfection was assessed for effectiveness regarding successful decolonization of multidrug-resistant bacteria.

Altogether, 170 cases of successful decolonization were observed, comprising 95 (55.8%) such events at sampling sites that were accessible to disinfecting procedures. The remaining 75 (44.2%) decolonization events had to be considered as spontaneous. In contrast, 95 out of 172 (55.2%) colonized isolation sites that were accessible to disinfection procedures were successfully decolonized. Patient compliance with the enforced hygiene procedures was associated with decolonization success. Systemic antibiotic therapy did not relevantly affect isolation time.

Disinfecting washing moderately supports local decolonization of multidrug-resistant pathogens in comparison with spontaneous decolonization rates if the patients’ compliance with the applied hygiene procedures is ensured.

Low Enteric Colonization with Multidrug-Resistant Pathogens in Soldiers Returning from Deployments- Experience from the Years 2007-2015

This assessment describes the enteric colonization of German soldiers 8–12 weeks after returning from mostly but not exclusively subtropical or tropical deployment sites with third-generation cephalosporin-resistant Enterobacteriaceae, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA). Between 2007 and 2015, 828 stool samples from returning soldiers were enriched in nonselective broth and incubated on selective agars for Enterobacteriaceae expressing extended-spectrum beta-lactamases (ESBL), VRE and MRSA. Identification and resistance testing of suspicious colonies was performed using MALDI-TOF-MS, VITEK-II and agar diffusion gradient testing (bioMérieux, Marcy-l’Étoile, France). Isolates with suspicion of ESBL were characterized by ESBL/ampC disc-(ABCD)-testing and molecular approaches (PCR, Sanger sequencing). Among the returnees, E. coli with resistance against third-generation cephalosporins (37 ESBL, 1 ESBL + ampC, 1 uncertain mechanism) were found in 39 instances (4.7%). Associated quinolone resistance was found in 46.2% of these isolates. Beta-lactamases of the bla_CTX-M group 1 predominated among the ESBL mechanisms, followed by the bla_CTX-M group 9, and bla_SHV. VRE of vanA-type was isolated from one returnee (0.12%). MRSA was not isolated at all. There was no clear trend regarding the distribution of resistant isolates during the assessment period. Compared with colonization with resistant bacteria described in civilians returning from the tropics, the colonization in returned soldiers is surprisingly low and stable. This finding, together with high colonization rates found in previous screenings on deployment, suggests a loss of colonization during the 8- to 12-week period between returning from the deployments and assessment.

Natural history and decolonization strategies for ESBL/carbapenem-resistant Enterobacteriaceae carriage: systematic review and meta-analysis

BACKGROUND

ESBL-producing Enterobacteriaceae and carbapenem-resistant Enterobacteriaceae (CRE) are rapidly spreading worldwide. Their natural reservoir is intestinal.

METHODS

We carried out a systematic review and meta-analysis to estimate CRE and ESBL carriage duration and to evaluate the effect of decolonization therapy. We included cohort and comparative studies examining the natural history of CRE/ESBL colonization, examining rates of carriage following decolonization or comparing decolonization and no decolonization conducted in the healthcare setting or in the community. A comprehensive search was conducted until November 2015. We compiled carriage rates at 1, 3, 6 and 12 months with and without decolonization therapy and assessed the effect of decolonization.

RESULTS

Thirty-seven studies fulfilled inclusion criteria. In healthcare settings, pooled ESBL/CRE colonization rates decreased without intervention from 76.7% (95% CI = 69.3%-82.8%) at 1 month to 35.2% (95% CI = 28.2%-42.9%) at 12 months of follow-up. Following decolonization, the rate was 37.1% (95% CI = 27.5%-47.7%) at end of therapy and 57.9% (95% CI = 43.1%-71.4%) at 1 month. In two randomized trials, carriage was significantly reduced at end of therapy (risk ratio = 0.42, 95% CI = 0.25-0.65), but the effect was not significant after 1 month (risk ratio = 0.72, 95% CI = 0.48-1.05), with no longer follow-up. Heterogeneity was explained by surveillance methodology, with no differences observed between ESBLs and CREs. Among community dwellers, ESBL colonization decreased from 52.3% (95% CI = 29.5%-74.2%) at 1 month to 19.2% (95% CI = 9.7%-34.4%) at 6 months.

CONCLUSIONS

A significant proportion of ESBL and CRE carriers remain colonized up to 1 year in the healthcare setting. While short-term decolonization therapy reduces carriage during therapy, its longer-term effects are unclear.

Multidrug-resistant bacteria in hematology patients: emerging threats

Multidrug-resistant (MDR) bacteria, particularly Gram negatives, such as Enterobacteriaceae resistant to third-generation cephalosporins or carbapenems and MDR Pseudomonas aeruginosa, are increasingly frequent in hematology patients. The prevalence of different resistant species varies significantly between centers. Thus, the knowledge of local epidemiology is mandatory for deciding the most appr-opriate management protocols. In the era of increasing antibiotic resistance, empirical therapy of febrile neutropenia should be individualized. A de-escalation approach is recommended in case of severe clinical presentation in patients who are at high risk for infection with a resistant strain. Targeted therapy of an MDR Gram negative usually calls for a combination treatment, although no large randomized trials exist in this setting. Infection control measures are the cornerstone of limiting the spread of MDR pathogens in hematology units.