Incidence of infection with multidrug-resistant Gram-negative bacteria and vancomycin-resistant enterococci in carriers: a systematic review and meta-regression analysis

A phase 2 randomized, placebo-controlled trial of inulin for the prevention of gut pathogen colonization and infection among patients admitted to the intensive care unit for sepsis

BACKGROUND

Patients admitted to the intensive care unit (ICU) often have gut colonization with pathogenic bacteria and such colonization is associated with increased risk for death and infection. We conducted a trial to determine whether a prebiotic would improve the gut microbiome to decrease gut pathogen colonization and decrease downstream risk for infection among newly admitted medical ICU patients with sepsis.

METHODS

This was a randomized, double-blind, placebo-controlled trial of adults who were admitted to the medical ICU for sepsis and were receiving broad-spectrum antibiotics. Participants were randomized 1:1:1 to placebo, inulin 16 g/day, or inulin 32 g/day which were given for seven days. The trial primary outcome was a surrogate measure for gut colonization resistance, namely the within-individual change from ICU admission to Day 3 in the relative abundance of short chain fatty acid (SCFA)-producing bacteria based on rectal swabs. Additional outcomes sought to evaluate the impact of inulin on the gut microbiome and downstream clinical effects.

RESULTS

Ninety participants were analyzed including 30 in each study group. There was no difference between study groups in the within-individual change in the relative abundance of SCFA-producing bacteria from ICU admission to ICU Day 3 (placebo: 0.0% change, IQR - 8·0% to + 7·4% vs. combined inulin: 0·0% change, IQR - 10·1% to + 4·8%; p = 0·91). At end-of-treatment on ICU Day 7, inulin did not affect SCFA-producer levels, microbiome diversity, or rates of gut colonization with pathogenic bacteria. After 30 days of clinical follow-up, inulin did not affect rates of death or clinical, culture-proven infection. Patients who died or developed culture-proven infections had lower relative abundance of SCFA-producing bacteria at ICU admission compared to those who did not (p = 0·03).

CONCLUSIONS

Prebiotic fiber had minimal impact on the gut microbiome in the ICU and did not improve clinical outcomes.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03865706.

Is intestinal colonization with multidrug-resistant Enterobacterales associated with higher rates of nosocomial Enterobacterales bloodstream infections?

OBJECTIVES

Intestinal colonization with multidrug-resistant Enterobacterales (MDRE-IC) increases the risk of MDRE bloodstream infection (BSI). However, its impact on the overall risk of nosocomial Enterobacterales bloodstream infections (nE-BSIs) remains unclear. This study aimed to determine this risk and identify associated factors in hospitalized patients.

DESIGN

This retrospective cohort study at a 3200-bed tertiary institution including patients hospitalized in 2019 who underwent MDRE rectal swab (RS) screening. Inclusion criteria were age ≥18 years, first RS in 2019, follow-up ≥7 days, and Enterobacterales BSIs >48 hours after RS. The primary outcome was the first nE-BSI during the follow-up period, analyzed using a Cox model.

RESULTS

Among 7006 patients, 817 (11.9%) had MDRE-IC. Most were male and primarily hospitalized in acute wards. nE-BSIs occurred in 433 (6.1%) patients and were more frequent in patients with MDRE-IC than the non-colonized group (adjusted hazard ratio [aHR] = 1.78, 95% confidence interval [CI]: 1.40-2.26). Intestinal colonization with extended-spectrum β-lactamase-producing and carbapenemase-resistant Enterobacterales showed similar risks for Enterobacterales BSI onset: aHR = 1.73 (95% CI: 1.33-2.24) and aHR = 2.02 (95% CI: 1.27-3.22), respectively.

CONCLUSIONS

In hospitalized patients, MDRE-IC is associated with a higher rate of nE-BSI than those without MDRE-IC, underscoring the urgent need for improved infection prevention and control measures, as well as optimized antibiotic use to mitigate this risk.

Management of vancomycin-resistant Enterococcus faecium in Dutch healthcare institutes: a nationwide survey

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VREfm) is an opportunistic pathogen, which can cause outbreaks in hospitals. In the Netherlands, several national guidelines and guidance documents on different aspects of VREfm management are available. Most available guidelines are written towards the hospital setting and only few on long-term care facilities (LTCFs). Moreover, not all aspects of VREfm management are covered, recommendations differ and the level of compliance to these guidelines is unknown. The aim of this study was to get insight into the routine VREfm policies in Dutch healthcare facilities with regard to screening, diagnostics and infection control measures.

METHODS

Online questionnaires were sent to representatives of Dutch hospitals and LTCFs. The questionnaire included questions regarding the definition of VRE, screening, diagnostics, patient isolation, cleaning procedures, VREfm clearance and VREfm outbreaks.

FINDINGS

The questionnaire was completed by 61 hospitals with a response rate of 84.1% and 57 LTCFs, mostly nursing homes. Most hospitals reported VREfm outbreaks in the previous decade, whereas only one LTCF reported an outbreak. Of the hospitals, 87% perform VREfm screening versus 50% of the LTCFs. VREfm-positive patients are isolated in 98% of hospitals and 83% of LTCFs. Protocols regarding how to unlabel VREfm-positive patients are in place in 84% of the hospitals and in 51% of LTCFs. The details of these measures differ substantially between healthcare facilities.

CONCLUSION

This study has shown that most hospitals and some LTCFs in the Netherlands have standard procedures for VREfm management to some level, although the comprehensiveness and details of the measures differ per hospital. More uniform policies would improve comparability of VREfm data on a regional/national level.

External validation of the ICU-CARB score to predict carbapenem-resistant gram-negative bacteria carriage in critically ill patients upon ICU admission: a multicenter analysis

BACKGROUND

Recognition of carbapenem-resistant gram-negative bacteria (CR-GNB) carriage is frequently delayed, which increases the risk of subsequent infection and transmission. Previously, we developed a scoring system to identify CR-GNB carriage upon intensive care unit (ICU) admission. Although the ICU-CARB score showed satisfactory performance, it has not been externally validated. In this study, therefore, we externally validated the ICU-CARB score.

METHODS

In the previous article, we introduced a risk-scoring system that incorporated seven key variables: neurological disease, high-risk department history, length of stay ≥ 14 days, ICU history, invasive mechanical ventilation, gastrointestinal tube placement, and carbapenem usage. To externally validate the ICU-CARB score, we conducted a study involving patients admitted to the ICUs of four tertiary hospitals between January 2021 and December 2023. Patients from three hospitals were grouped into Cohort I (n = 815) and those from the fourth hospital into Cohort II (n = 1602). Model calibration, discrimination, and performance were then assessed.

RESULTS

A total of 2417 patients were included, among which 289 (12%) carried CR-GNB upon ICU admission. Neurological disease, high-risk department history and length of stay ≥ 14 days were still 3 most important contributing factors in the scoring system. The ICU-CARB score exhibited high calibration, with an area under the receiver operating characteristic curve of 0.825 (95% confidence interval [CI], 0.778-0.873) for Cohort I and 0.823 (95% CI, 0.791-0.855) for Cohort II. The ICU-CARB score showed a highly positive association with CR-GNB carriage in both cohort I (C = 0.315; P < 0.001) and Cohort II (C = 0.381; P < 0.001).

CONCLUSIONS

Despite differences in patient population characteristics, the ICU-CARB score for CR-GNB carriage upon ICU admission exhibited good discrimination in external validation, supporting its potential generalizability to other ICU settings.

Bacteremic nosocomial pneumonia caused by Gram-negative bacilli: results from the nationwide ALARICO study in Italy

PURPOSE

To describe the clinical characteristics and outcomes of patients with nosocomial pneumonia (NP) caused by carbapenem-resistant Gram-negative bacilli (CR-GNB) and to compare them to patients with NP caused by carbapenem-susceptible (CS)-GNB.

METHODS

Prospective observational multicenter study including patients with bacteremic NP caused by GNB from the ALARICO Network (June 2018-January 2020). The primary outcome measure was 30-day mortality. A Cox regression analysis was performed to identify factors independently associated with 30-day mortality. Hazard ratio (HR) and 95% confidence intervals (CI) were calculated.

RESULTS

Overall, 167 patients with GNB NP were included: 101 with bacteremic NP caused by CR-GNB (n = 39 by KPC-producing Klebsiella pneumoniae, n = 29 by carbapenem-resistant Acinetobacter baumannii, n = 28 by carbapenem-resistant Pseudomonas aeruginosa, n = 5 by MBL-producing Klebsiella pneumoniae) and 66 cases of bacteremic CS-GNB NP. Thirty-day mortality rate was higher in patients with NP caused by CR-GNB compared to those with NPcaused by CS-GNB (46.5% vs 30.3%, p = 0.036). On multivariable analysis, age (HR 1.044, 95% CI 1.021-1.067, p < 0.001), hematological malignancy (HR 4.307, 95% CI 1.924-9.643, p < 0.001) and septic shock (HR 3.668, 95% CI 2.001-6.724, p < 0.001) were factors independently associated with 30-day mortality, while the receipt of adequate antibiotic therapy within 24 h from infection onset (HR 0.495, 95% CI 0.252-0.969, p = 0.04) was a protective factor. Carbapenem resistance was not associated with increased risk of mortality (HR 1.075, 95% CI 0.539-2.142, p = 0.837).

CONCLUSIONS

Patients with bacteremic NP caused by CR-GNB have high mortality rate. Strategies to reduce the time from infection to the administration of adequate antibiotic therapy should be implemented in patients with NP.

Persistence of OXA-48-producing ST-22 Citrobacter freundii in patients and the hospital environment, Paris, France, 2016 to 2022

In 2016-2019, hospital A's haematology ward experienced an outbreak of OXA-48-producing ST-22 Citrobacter freundii strains, with toilets identified as source of transmission. Between 2020 and 2022, 28 strains of OXA-48-producing ST-22 C. freundii were isolated on other wards. This study aimed to determine whether all OXA-48-producing ST-22 C. freundii strains belonged to the same clone and to investigate the persistence of this clone using whole genome sequencing. OXA-48-producing ST-22 C. freundii strains collected from patients (n = 33) and from the hospital environment (n = 20) of seven wards were sequenced using Illumina technology and clonal relationships were determined using single nucleotide polymorphism (SNP). Phylogenetic analyses were performed on 53 strains from hospital A and on 240 epidemiologically unrelated carbapenem-resistant ST-22 C. freundii isolated from elsewhere in France. SNP analysis suggested long-lasting persistence of the same clone for more than 6 years. Phylogenetic analysis showed that 52 of 53 strains isolated in hospital A belonged to the same cluster and were different from the 240 epidemiologically unrelated C. freundii ST-22. Our data suggest that this clone can persist in hospital environments for years, representing a risk for hospital-acquired infections and outbreaks. Reservoir management is essential to prevent further transmission.

Long-term Risk of Infection Among Patients Colonized With Antimicrobial-Resistant Pathogens: A Population-wide Cohort Study

Background

Antimicrobial-resistant (AMR) pathogens represent an ongoing global health burden. Colonization is often a prerequisite for infection, but the risk of infection after AMR colonization is not well understood. Using population-level health administrative data, we sought to investigate the risk of infection with the same AMR organism after detection of colonization.

Methods

We conducted a retrospective population-wide cohort study among residents of Ontario, Canada, over a 5-year period to determine the risk of infection after detection of colonization with the following AMR pathogens: methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended-spectrum β-lactamase-producing Enterobacterales, and carbapenemase-producing Enterobacterales. We also examined the effects of age, sex, and health care setting of colonization detection on subsequent infection risk.

Results

There were 69 998 individuals with a positive AMR pathogen surveillance test result during the study period, 15.6% of which subsequently developed a sterile or nonsterile site infection within a median 57 days (IQR, 11-228). Infection rates varied among organisms: 18.3% for methicillin-resistant S aureus within a median 57 days (IQR, 10-239), 2.8% for vancomycin-resistant Enterococcus within a median 37 days (IQR, 11-119), 21.5% for extended-spectrum β-lactamase-producing Enterobacterales within a median 71 days (IQR, 18-231), and 20.3% for carbapenemase-producing Enterobacterales within a median 10 days (IQR, 3-42). A positive surveillance test result detected in a hospital was associated with increased infection risk after colonization as compared with the community setting.

Conclusions

The overall infection rate after colonization with an AMR pathogen was high for most organisms, highlighting the importance of detecting colonization from both an infection control and empiric antibiotic selection perspective.

Evaluating the Efficacy of Inhaled Colistin via Two Nebulizer Types in Ventilator-Associated Pneumonia: Prospective Randomized Trial

Backgroud: This prospective randomized trial evaluated the clinical efficacy of inhaled colistin administered through two distinct nebulizer types, a vibrating mesh nebulizer (VMN) and a jet nebulizer (JN), in the treatment of ventilator-associated pneumonia caused by multidrug-resistant bacteria. In addition, an in vitro model was used to determine the optimal delivery of colistin. Method: Thirty-two patients prescribed intravenous (IV) colistin inhalation were randomized to receive either a VMN (n = 17) or a JN (n = 15), then compared to the control group (IV alone) over a 7-to 10-day period. The primary endpoint was the clinical pulmonary infection score (CPIS), and the secondary endpoints were the Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACE) score, and duration of ventilator use. Results: Results from in vitro testing demonstrated that VMN delivered a significantly higher colistin dose than JN (35.68 ± 3.55% vs. 23.56 ± 3.31%; p < 0.001) when positioned at the humidifier inlet. Compared to the IV alone group, the IV with inhalation group yielded significant improvements in CPIS, SOFA score, and APACHE score on day 7; nevertheless, clinical outcomes between the two nebulizers were statistically indistinguishable. Conclusions: In conclusion, although VMN delivers a higher dose in vitro, both nebulizers yielded comparable clinical outcomes. This study was registered at US Clinical Trial Registration (NCT04633317).

Role of Preoperative Multiple-Drug-Resistant Bacteria Intestinal Colonization in Cardiac Surgery: A Retrospective Study

Background/Objectives: Multiple-drug-resistant (MDR) bacteria are pathogens resistant to three or more antibiotic classes, and infection with these bacteria is associated with increased mortality, morbidity, and hospital management costs. Given the rise in antibiotic resistance, selecting appropriate antimicrobial drugs and avoiding the unnecessary use of new antibiotics are crucial. Due to their nosocomial nature, monitoring and preventing MDR infections are essential. Methods: This study enrolled patients who underwent cardiac surgery from January 2020 to May 2022. The patients included were those 18 years or older who tested positive for MDR intestinal colonization before surgery. Excluded were patients who tested positive after surgery, or were younger than 18, pregnant, or lactating. For each positive patient, the National Surgical Quality Improvement Program (NSQIP) score was calculated. The data collected included age, gender, body mass index (BMI), the type of surgery, the intensive care unit (ICU) length of stay, ICU readmission, mortality, and other infections (pneumonia, bacteremia, or surgical site infection) to establish a control group and postoperative outcome measures. Results: No statistically significant differences were found between the groups regarding the ICU length of stay, new ICU admissions, or mortality. Additionally, there were no differences in the infection rates, such as bacteremia, wound infections, and pneumonia. Conclusions: Preoperative rectal colonization by MDR bacteria does not appear to worsen postoperative outcomes for cardiac surgery patients. These findings suggest that patients with a preoperative MDR-positive rectal sample might undergo cardiac surgery without significantly increased risk. Besides the limitations of this study, pre-surgical antibiotic prophylaxis may not need to be adjusted for patients with preoperative MDR positivity.

Rapid design of bacteriophage cocktails to suppress the burden and virulence of gut-resident carbapenem-resistant Klebsiella pneumoniae

Antibiotic use can lead to the expansion of multi-drug-resistant pathobionts within the gut microbiome that can cause life-threatening infections. Selective alternatives to conventional antibiotics are in dire need. Here, we describe a Klebsiella PhageBank for the tailored design of bacteriophage cocktails to treat multi-drug-resistant Klebsiella pneumoniae. Using a transposon library in carbapenem-resistant K. pneumoniae, we identify host factors required for phage infection in major Klebsiella phage families. Leveraging the diversity of the PhageBank, we formulate phage combinations that eliminate K. pneumoniae with minimal phage resistance. Optimized cocktails selectively suppress the burden of K. pneumoniae in the mouse gut and drive the loss of key virulence factors that act as phage receptors. Phage-mediated diversification of bacterial populations in the gut leads to co-evolution of phage variants with higher virulence and broader host range. Altogether, the Klebsiella PhageBank charts a roadmap for phage therapy against a critical multidrug-resistant human pathogen.

Personalized CZA-ATM dosing against an XDR E. coli in liver transplant patients; the application of the in vitro hollow fiber system

BACKGROUND

A patient with an extensively drug-resistant (XDR) New Delhi metallo-β-lactamase (NDM) and oxacillinase (OXA-48) producing Escherichia coli (E. coli) infection was awaiting orthotopic liver transplant. There is no standardized antibiotic prophylaxis regimen; however, in line with the Infectious Diseases Society of America guidance, an antibiotic prophylactic regimen of ceftazidime-avibactam 2.5 g TDS with aztreonam 2 g three times a day (TDS) IV was proposed.

METHODS

The hollow fiber system (HFS) was applied to inform the individualized pharmacodynamic outcome likelihood prior to prophylaxis.

RESULTS

A 4-log reduction in CFU/mL in the first 10 h of the regimen exposure was observed; however, the killing dynamics were slow and six 8-hourly infusions were required to reduce bacterial cells to below the limit of quantification. Thus, the HFS supported the use of the regimen for infection clearance; however, it highlighted the need for several infusions. Standard local practice is to administer prophylaxis antibiotics at induction of orthotopic liver transplantation (OLT); however, the HFS provided data to rationalize earlier dosing. Therefore, the patient was dosed at 24 h prior to their OLT induction and subsequently discharged 8 days after surgery.

CONCLUSION

The HFS provides a dynamic culture solution for informing individualized medicine by testing antibiotic combinations and exposures against the bacterial isolates cultured from the patient's infection. .

Risk factors for infection after carbapenem-resistant Acinetobacter baumannii colonization

PURPOSE

Predicting infection risk in carbapenem-resistant Acinetobacter baumannii (CRAB) colonized patients may help in improving timely appropriate antibiotic therapy. This study aims to explore risk factors for developing infections in hospitalized patients with previous CRAB colonization.

METHODS

We performed an observational retrospective cohort study at ASST Sette Laghi-Varese Hospital between January 2020 and December 2022. All consecutive adult (> 18 years old) hospitalized patients with documented colonization by CRAB at any anatomical site or with CRAB infections preceded by CRAB colonization were included. Univariate and multivariate analyses were performed to investigate infection risk factors.

RESULTS

Overall, 144 patients were included in the study: 104 colonized only and 40 infected patients. Colonization and infection rates significantly changed over the years (2020-2022, p < 0.001). The incidence of infections in CRAB carriers was 27.8% (40/144). Median time from colonization to infection was 4 days (IQR 1-8.5). Overall, inhospital mortality was 32.7% and 55.0% in colonized only and infected patients, respectively. At the multivariable logistic regression cardiovascular disease (OR 5.83, 95% CI 1.12-30.43, p = 0.037), COVID-19 (OR 3.72, 95% CI 1.16-11.91, p = 0.027) and intensive care unit (ICU) admission (OR 8.83, 95% CI 2.94-26.51, p < 0.001) were risk factors independently associated with cardiovascular disease CRAB infection after colonization.

CONCLUSIONS

We observed an increased infection risk in patients colonized with CRAB with cardiovascular disease, COVID-19 and admitted in ICU setting. Additional evidence is needed to identify predictors of infection in colonized patients.

Does the removal of isolation for VRE-infected patients change the incidence of health care-associated VRE?: A systematic review and meta-analysis

BACKGROUND

Several single-center studies have suggested that eliminating isolation for vancomycin-resistant enterococci (VRE) control in the context of endemic or nonoutbreak settings, has no impact on infection rates. We performed a systematic review and meta-analysis on the impact of discontinuing isolation.

METHODS

We searched PubMed, Embase, the Cochrane Library, and Web of Science through April 10, 2024 for studies evaluating discontinuation of isolation for VRE. Subgroup analyses assessed sources of heterogeneity.

RESULTS

Nine studies were included in the final review. Four reported the incidence of hospital-acquired VRE (HA-VRE) infections and 5 reported the incidence of hospital-acquired VRE bloodstream infections (HA-VRE BSI). No significant difference between the rates of HA-VRE infection before and after stopping isolation was observed (risk ratios, 0.93; 95% confidence interval, 0.68-1.26; P = .62), as well as no significant difference on the incidence of HA-VRE BSI (risk ratios, 0.68; 95% confidence interval, 0.44-1.07, P = .09). Furthermore, we conducted 2 subgroup analyses: one stratified by whether the studies were conducted during Coronavirus Disease 19 (COVID-19), and the other stratified by whether clinicians continued to use personal protective equipment. Both analyses revealed no significant differences in the incidence of HA-VRE BSI and termination of isolation between the subgroups.

CONCLUSIONS

In the context of endemic or nonoutbreak settings, discontinuation of isolation for VRE patients has not been associated with an increased rate of HA-VRE infections.

Epidemiology of subsequent carbapenem-resistant enterobacterales (CRE) infection among rectal carriers: A meta-analysis of incidence, risk factors and their association with geographic region and age

BACKGROUND

This study aimed to assess the incidence and risk factors of subsequent carbapenem-resistant Enterobacterales (CRE) infection among rectal carriers, and their association with geographic region and age.

METHODS

A meta-analysis of studies investigating incidence and/or risk factors of subsequent CRE infection among rectal carriers was conducted, with subgroup analyses by geographic region and age. PubMed, Embase, Web of Science, and Cochrane Library were searched (published from inception to 31 January 2024). This study is registered with PROSPERO (CRD42023444420).

RESULTS

Of 4459 studies identified, 24 studies with 8188 CRE rectal carriers were included. The pooled incidence of subsequent CRE infection was 20.6% (95% CI 15.9-25.8). The highest incidence was seen in America (23.6%, 95% CI 14.2-34.5), followed by Europe (20.9%, 95% CI 12.5-30.8) and Asia (19.8%, 95% CI 12.7-27.9). Children had a greater incidence (26.7%, 95% CI 21.3-32.3) than adults (19.8%, 95% CI 14.9-25.2). Fourteen factors were associated with subsequent CRE infection. In Asia, the most notable risk factor was gastritis (odds ratio [OR] 4.95 95% CI 1.87-13.11). In Europe, admission to the intensive care unit was prominent (OR 2.76 95% CI 1.14-6.65). In the America, the use of a urinary Foley catheter (OR 4.33 95% CI 1.06-17.70) was dominant. Admission to the intensive care unit was most notable in adults (OR 3.01 95% CI 1.80-5.02), while mechanical ventilation was shown the greatest significance in children (OR 15.61 95% CI 4.39-55.47).

CONCLUSIONS

Risk of subsequent CRE infection among rectal carriers was critical. Identifying the risk factors for subsequent infection could help in developing more potent prevention and control measures to reduce CRE infection.

The role of colonization with resistant Gram-negative bacteria in the treatment of febrile neutropenia after stem cell transplantation

BACKGROUND

Febrile neutropenia (FN) is a common complication of stem cell transplantation.

AIM

To evaluate the frequency of sepsis in patients with FN colonized with resistant Gram-negative bacteria (extended-spectrum β-lactamase (ESBL)-positive, multidrug-resistant (MDR) Pseudomonas aeruginosa) and the choice of primary antibiotic in colonized patients.

METHODS

This retrospective study analysed data from patients undergoing haematopoietic stem cell transplantation from January 2018 to September 2022. Data were extracted from the hospital information system.

FINDINGS

Carbapenem as the primary antibiotic of choice was chosen in 10.9% of non-colonized +/-AmpC patients, 31.5% of ESBL+ patients, and 0% of MDR P. aeruginosa patients. Patients with FN and MDR P. aeruginosa colonization had a high prevalence of sepsis (namely 100%, P = 0.0197). The spectrum of sepsis appeared to be different, with Gram-negative bacilli predominating in the ESBL+ group (OR: 5.39; 95% CI: 1.55-18.76; P = 0.0123). Colonizer sepsis was present in 100% of sepsis with MDR P. aeruginosa colonization (P = 0.002), all in allogeneic transplantation (P = 0.0003), with a mortality rate of 33.3% (P = 0.0384). The incidence of sepsis in patients with ESBL+ colonization was 25.9% (P = 0.0197), with colonizer sepsis in 50% of sepsis cases (P = 0.0002), most in allogeneic transplantation (P = 0.0003).

CONCLUSION

The results show a significant risk of sepsis in FN with MDR P. aeruginosa colonization, a condition almost exclusively caused by the colonizer. At the same time, a higher risk of Gram-negative sepsis has been demonstrated in patients colonized with ESBL+ bacteria.

The STING signaling pathways and bacterial infection

As antibiotic-resistant bacteria continue to emerge frequently, bacterial infections have become a significant and pressing challenge to global public health. Innate immunity triggers the activation of host responses by sensing "non-self" components through various pattern recognition receptors (PRRs), serving as the first line of antibacterial defense. Stimulator of interferon genes (STING) is a PRR that binds with cyclic dinucleotides (CDN) to exert effects against bacteria, viruses, and cancer by inducing the production of type I interferon and inflammatory cytokines, and facilitating regulated cell death. Currently, drugs targeting the STING signaling pathway are predominantly applied in the fields of modulating host immune defense against cancer and viral infections, with relatively limited application in treating bacterial infections. Given the significant immunomodulatory functions of STING in the interaction between bacteria and hosts, this review summarizes the research progress on STING signaling pathways and their roles in bacterial infection, as well as the novel functions of STING modulators, aiming to offer insights for the development of antibacterial drugs.

Zidovudine in synergistic combination with nitrofurantoin or omadacycline: in vitro and in murine urinary tract or lung infection evaluation against multidrug-resistant Klebsiella pneumoniae

Limited treatment options and multidrug-resistant (MDR) Klebsiella pneumoniae present a significant therapeutic challenge, underscoring the need for novel approaches. Drug repurposing is a promising tool for augmenting the activity of many antibiotics. This study aimed to identify novel synergistic drug combinations against K. pneumoniae based on drug repurposing. We used the clinically isolated GN 172867 MDR strain of K. pneumoniae to determine the reversal resistance activity of zidovudine (AZT). The combined effects of AZT and various antibiotics, including nitrofurantoin (NIT) and omadacycline (OMC), were examined using the checkerboard method, growth curves, and crystal violet assays to assess biofilms. An in vitro combination activity testing was carried out in 12 isolates of K. pneumoniae. In vivo murine urinary tract and lung infection models were used to evaluate the therapeutic effects of AZT + NIT and AZT + OMC, respectively. The fractional inhibitory concentration index and growth curve demonstrated that AZT synergized with NIT or OMC against K. pneumoniae strains. In addition, AZT + NIT inhibited biofilm formation and cleared mature biofilms. In vivo, compared with untreated GN 172867-infected mice, AZT + NIT and AZT + OMC treatment decreased colony counts in multiple tissues (P < 0.05) and pathological scores in the bladder and kidneys (P < 0.05) and increased the survival rate by 60% (P < 0.05). This study evaluated the combination of AZT and antibiotics to treat drug-resistant K. pneumoniae infections and found novel drug combinations for the treatment of acute urinary tract infections. These findings suggest that AZT may exert significant anti-resistance activity.

The impact of colonization by multidrug resistant bacteria on graft survival, risk of infection, and mortality in recipients of solid organ transplant: systematic review and meta-analysis

BACKGROUND

The Global increase in colonization by multidrug-resistant (MDR) bacteria poses a significant concern. The precise impact of MDR colonization in solid organ transplant recipients (SOTR) remains not well established.

OBJECTIVES

To assess the impact of MDR colonization on SOTR's mortality, infection, or graft loss.

METHODS AND DATA SOURCES

Data from PROSPERO, OVID Medline, OVID EMBASE, Wiley Cochrane Library, ProQuest Dissertations, Theses Global, and SCOPUS were systematically reviewed, spanning from inception until 20 March 2023. The study protocol was registered with PROSPERO (CRD42022290011) and followed the PRISMA guidelines. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, INTERVENTIONS, AND ASSESSMENT OF RISK OF BIAS: Cohorts and case-control studies that reported on adult SOTR colonized by Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum β-lactamase (ESBL) or carbapenem-resistant Enterobacteriaceae. (CRE), or MDR-pseudomonas, and compared to noncolonized, were included. Two reviewers assessed eligibility, conducted a risk of bias evaluation using the Newcastle-Ottawa Scale, and rated certainty of evidence using the GRADE approach.

METHODS OF DATA SYNTHESIS

We employed RevMan for a meta-analysis, using random-effects models to compute pooled odds ratios (OR) and 95% confidence intervals (CI). Statistical heterogeneity was determined using the I2 statistic.

RESULTS

15,202 SOTR (33 cohort, six case-control studies) were included, where liver transplant and VRE colonization (25 and 14 studies) were predominant. MDR colonization significantly increased posttransplant 1-year mortality (OR, 2.35; 95% CI, 1.63-3.38) and mixed infections (OR, 10.74; 95% CI, 7.56-12.26) across transplant types (p < 0.001 and I2 = 58%), but no detected impact on graft loss (p 0.41, I2 = 0). Subgroup analysis indicated a higher association between CRE or ESBL colonization with outcomes (CRE: death OR, 3.94; mixed infections OR, 24.8; ESBL: mixed infections OR, 10.3; no mortality data) compared to MRSA (Death: OR, 2.25; mixed infection: OR, 7.75) or VRE colonization (Death: p 0.20, mixed infections: OR, 5.71).

CONCLUSIONS

MDR colonization in SOTR, particularly CRE, is associated with increased mortality. Despite the low certainty of the evidence, actions to prevent MDR colonization in transplant candidates are warranted.

Key environmental exposure pathways to antimicrobial resistant bacteria in southern Malawi: A SaniPath approach

Antimicrobial resistance (AMR) poses a severe global health threat, yet the transmission pathways of AMR within communal public environments, where humans and animals interact, remain poorly explored. This study investigated AMR risk pathways, prevalence, and seasonality of extended-spectrum β-lactamase (ESBL) producing E. coli and K. pneumoniae, and observed practices contributing to environmental contamination within urban, peri-urban, and rural Malawi. Using the SaniPath tool, in August 2020, transect walks across three Malawian study sites identified potential AMR exposure pathways, including drains, standing water, soil, and areas of communal hand contact. Subsequently, from September-2020 to August-2021, 1440 environmental samples were collected at critical points along exposure routes (n = 40/month from each site). These underwent microbiological analysis using chromogenic agar techniques to detect the presence of ESBL E. coli and ESBL K. pneumoniae. Results showed the highest ESBL prevalence in urban environments (68.1 %, 95%CI = 0.64-0.72, p < 0.001) with a higher ESBL presence seen in drains (58.8 %, 95%CI = 055-0.62, p < 0.001) and soil (54.1 %, 95%CI = 0.46-0.62, p < 0.001) compared to other pathways. Environmental contamination was attributed to unavailability and poor condition of sanitation and hygiene infrastructure based on key informant interviews with community leaders (n = 9) and confirmed by independent observation. ESBL prevalence varied between seasons (χ2 (2,N = 1440) = 10.89, p = 0.004), with the highest in the hot-dry period (55.8 % (n = 201)). Prevalence also increased with increased rainfall (for ESBL E.coli). We highlight that community environments are likely to be a crucial component in AMR transmission, evident in the abundance of ESBL bacteria in identified exposure pathways. Additionally, poor sanitation infrastructure and practices coupled with seasonal dynamics further affect the presence of ESBLs in communal environments. Therefore, a context appropriate whole system approach that tackles infrastructure and behavioural factors, supported by effective surveillance is required to impact AMR and a range of aligned development challenges in these settings.

Public health case for microbiome-sparing antibiotics and new opportunities for drug development

Although antibiotics remain a cornerstone of modern medicine, the issues of widespread antibiotic resistance and collateral damage to the microbiome from antibiotic use are driving a need for drug developers to consider more tailored, patient-directed products to avoid antibiotic-induced perturbations of the structure and function of the indigenous microbiota. This perspective summarizes a cascade of microbiome health effects that is initiated by antibiotic-mediated microbiome disruption at an individual level and ultimately leads to infection and transmission of multidrug-resistant pathogens across patient populations. The scientific evidence behind each of the key steps of this cascade is presented. The interruption of this cascade through the use of highly targeted, microbiome-sparing antibiotics aiming to improve health outcomes is discussed. Further, this perspective reflects on some key clinical trial design and reimbursement considerations to be addressed as part of the drug development path.

Identification and Functional Analysis of ncRNAs Regulating Intrinsic Polymyxin Resistance in Foodborne Proteus vulgaris

Polymyxin, known as the "last line of defense" against bacterial infection, exerts a significant inhibitory effect on a wide range of Gram-negative pathogenic bacteria. The presence of strains, specifically Proteus vulgaris species, displaying intrinsic polymyxin resistance poses significant challenges to current clinical treatment. However, the underlying mechanism responsible for this intrinsic resistance remains unclear. Bacterial non-coding RNAs (ncRNAs) are abundant in genomes and have been demonstrated to have significant regulatory roles in antibiotic resistance across various bacterial species. However, it remains to be determined whether ncRNAs in Proteus vulgaris can regulate intrinsic polymyxin resistance. This study focused on investigating the foodborne Proteus vulgaris strain P3M and its intrinsic polymyxin resistance regulation mediated by ncRNAs. Through a combination of bioinformatics analysis, mutant construction, and phenotypic experimental verification, we successfully identified the ncRNAs involved and their potential target genes. These findings serve as an essential foundation for the precise identification of ncRNAs participating in the intricate regulation process of polymyxin resistance. Additionally, this study offers valuable insights into the efficient screening of bacterial ncRNAs that contribute positively to antibiotic resistance regulation.

Bacterial diversity and specific taxa are associated with decolonization of carbapenemase-producing enterobacterales after fecal microbiota transplantation

OBJECTIVES

We evaluated the effect of fecal microbiota transplantation (FMT) on the clearance of carbapenemase-producing Enterobacterales (CPE) carriage.

METHODS

We performed a prospective, multi-center study, conducted among patients who received a single dose of FMT from one of four healthy donors. The primary endpoint was complete clearance of CPE carriage two weeks after FMT with a secondary endpoint at three months. Shotgun metagenomic sequencing was performed to assess gut microbiota composition of donors and recipients before and after FMT.

RESULTS

Twenty CPE-colonized patients were included in the study, where post-FMT 20% (n = 4/20) of patients met the primary endpoint and 40% (n = 8/20) of patients met the secondary endpoint. Kaplan-Meier curves between patients with FMT intervention and the control group (n = 82) revealed a similar rate of decolonization between groups. Microbiota composition analyses revealed that response to FMT was not donor-dependent. Responders had a significantly lower relative abundance of CPE species pre-FMT than non-responders, and 14 days post-FMT responders had significantly higher bacterial species richness and alpha diversity compared to non-responders (p < 0.05). Responder fecal samples were also enriched in specific species, with significantly higher relative abundances of Faecalibacterium prausnitzii, Parabacteroides distasonis, Collinsella aerofaciens, Alistipes finegoldii and Blautia_A sp900066335 (q<0.01) compared to non-responders.

CONCLUSION

FMT administration using the proposed regimen did not achieve statistical significance for complete CPE decolonization but was correlated with the relative abundance of specific bacterial taxa, including CPE species.

Ceftazidime-Avibactam as a Salvage Treatment for Severely Infected Immunosuppressed Children

Background

Multidrug-resistant Gram-negative bacteria (MDR-GNB) are becoming increasingly common around the world, with carbapenems frequently serving as a last resort but being threatened by the growing incidence of carbapenemase-producing bacteria. Ceftazidime-avibactam (CAZ/AVI) is a potential agent against MDR-GNB but with limited clinical experience, particularly in critically ill immunosuppressed children.

Methods

This study analyzed the use of CAZ/AVI as salvage treatment in severely infected immunosuppressed children from September 2019 to July 2022. Patients with confirmed GNB infection who received CAZ/AVI were matched with patients who received other antibiotics.

Results

Twenty-five critically ill immunosuppressed children treated with CAZ/AVI were included. The majority had hematologic diseases. All patients presented with sepsis in all 30 courses. Septic shock presented in 36.7% of these courses. The primary sites of infection included bloodstream infection (20.0%), skin and skin structure infection (20.0%), intra-abdominal infection (13.3%) and hospital-acquired pneumonia (10.0%). Twelve of the 25 (48.0%) patients had positive microbiological cultures, mainly Pseudomonas aeruginosa and Klebsiella pneumoniae, including 5 carbapenem-resistant GNB-infected cases. Fifteen (50.0%) courses presented clinical improvement. For the initial course of each patient, the clinical response rate of the GNB recovered group was significantly higher than that of the group without GNB recovery (66.7% vs 23.1%, P = 0.047). The 14-day and 30-day mortality rates were 24.0% and 28.0%, respectively, which were significantly correlated with the absence of GNB recovery (P = 0.004 and 0.024, respectively) and hospital-acquired pneumonia as the primary site of infection (P = 0.001 and 0.006, respectively). There was no significant difference in major outcomes between patients who received CAZ/AVI and matched patients who received other antibiotics.

Conclusion

CAZ/AVI could be considered a salvage strategy for immunosuppressed children with confirmed GNB infection. Caution should be taken when CAZ/AVI is applied to these patients in the absence of GNB recovery.

The Natural History of Carbapenemase-Producing Enterobacterales: Progression From Carriage of Various Carbapenemases to Bloodstream Infection

BACKGROUND

Little is known about the risk of progression from carbapenemase-producing Enterobacterales (CPE) carriage to CPE bloodstream infection (BSI) outside of high-risk settings. We aimed to determine the incidence of CPE BSI among CPE carriers and to assess whether the incidence differs by carbapenemase, species, and setting.

METHODS

We conducted a nationwide population-based retrospective cohort study using national databases. The cohort consisted of all patients in Israel with CPE detected by screening from 1 January 2020 to 10 October 2022. We calculated the cumulative incidence of CPE BSI within 1 year among CPE carriers. We used a competing-risks model with BSI as the outcome and death as the competing risk.

RESULTS

The study included 6828 CPE carriers. The cumulative incidence of CPE BSI was 2.4% (95% confidence interval [CI], 2.1-2.8). Compared with Klebsiella pneumoniae carbapenemase (KPC), the subhazard of BSI was lower for New Delhi metallo-β-lactamase (NDM) (adjusted subhazard ratio [aSHR], 0.72; 95% CI, .49-1.05) and oxacillinase-48-like (OXA-48-like) (aSHR, 0.60; 95% CI, .32-1.12) but these differences did not reach statistical significance. Compared with K. pneumoniae, the subhazard of BSI was lower for carriers of carbapenemase-producing Escherichia coli (aSHR, 0.33; 95% CI, .21-.52). The subhazard of BSI was higher among patients with CPE carriage first detected in intensive care units (aSHR, 2.10; 95% CI, 1.27-3.49) or oncology/hematology wards (aSHR, 3.95; 95% CI, 2.51-6.22) compared with medical wards.

CONCLUSIONS

The risk of CPE BSI among CPE carriers is lower than previously reported in studies that focused on high-risk patients and settings. The risk of BSI differs significantly by bacterial species and setting, but not by carbapenemase.

Challenges for developing bacterial CA inhibitors as novel antibiotics

Acetazolamide, methazolamide, ethoxzolamide and dorzolamide, classical sulfonamide carbonic anhydrase (CA) inhibitors (CAIs) designed for targeting human enzymes, were also shown to effectively inhibit bacterial CAs and were proposed for repurposing as antibacterial agents against several infective agents. CAs belonging to the α-, β- and/or γ-classes from pathogens such as Helicobacter pylori, Neisseria gonorrhoeae, vacomycin resistant enterococci (VRE), Vibrio cholerae, Mycobacterium tuberculosis, Pseudomonas aeruginosa and other bacteria were considered as drug targets for which several classes of potent inhibitors have been developed. Treatment of some of these pathogens with various classes of such CAIs led to an impairment of the bacterial growth, reduced virulence and for drug resistant bacteria, a resensitization to clinically used antibiotics. Here I will discuss the strategies and challenges for obtaining CAIs with enhanced selectivity for inhibiting bacterial versus human enzymes, which may constitute an important weapon for addressing the drug resistance to β-lactams and other clinically used antibiotics.

Enhanced Antibacterial Activity of Vancomycin Loaded on Functionalized Polyketones

Today, polymeric drug delivery systems (DDS) appear as an interesting solution against bacterial resistance, having great advantages such as low toxicity, biocompatibility, and biodegradability. In this work, two polyketones (PK) have been post-functionalized with sodium taurinate (PKT) or potassium sulfanilate (PKSK) and employed as carriers for Vancomycin against bacterial infections. Modified PKs were easily prepared by the Paal-Knorr reaction and loaded with Vancomycin at a variable pH. All polymers were characterized by FT-IR, DSC, TGA, SEM, and elemental analysis. Antimicrobial activity was tested against Gram-positive Staphylococcus aureus ATCC 25923 and correlated to the different pHs used for its loading (between 2.3 and 8.8). In particular, the minimum inhibitory concentrations achieved with PKT and PKSK loaded with Vancomycin were similar, at 0.23 μg/mL and 0.24 μg/mL, respectively, i.e., six times lower than that with Vancomycin alone. The use of post-functionalized aliphatic polyketones has thus been demonstrated to be a promising way to obtain very efficient polymeric DDS.

Controlled release of vancomycin from PEGylated fibrinogen polyethylene glycol diacrylate hydrogel

Surgical site infection (SSI) is a common issue post-surgery which often prolongs hospitalization and can lead to serious complications such as sternal wound infection following cardiac surgery via median sternotomy. Controlled release of suitable antibiotics could allow maximizing drug efficacy and safety, and therefore achieving a desired therapeutic response. In this study, we have developed a vancomycin laden PEGylated fibrinogen-polyethylene glycol diacrylate (PF-PEGDA) hydrogel system that can release vancomycin at a controlled and predictable rate to be applied in SSI prevention. Two configurations were developed to study effect of the hydrogel on drug release, namely, vancomycin laden hydrogel and vancomycin solution on top of blank hydrogel. The relationship between the rigidity of the hydrogel and drug diffusion was found to comply with a universal power law, i.e., softer hydrogels result in a greater diffusion coefficient hence faster release rate. Besides, vancomycin laden hydrogels exhibited burst release, whereas the vancomycin solution on top of blank hydrogels exhibited lag release. A mathematical model was developed to simulate vancomycin permeation through the hydrogels. The permeation of vancomycin can be predicted accurately by using the mathematical model, which provided a useful tool to customize drug loading, hydrogel thickness and stiffness for personalized medication to manage SSI. To evaluate the potential of hydrogels for bone healing applications in cardiovascular medicine, we performed a proof-of-concept median sternotomy in rabbits and applied the hydrogels. The hydrogel formulations accelerated the onset of osteo-genetic processes in rabbits, demonstrating its potential to be used in human.

Gut colonization with multidrug resistant organisms in the intensive care unit: a systematic review and meta-analysis

BACKGROUND

Gut colonization with multidrug-resistant organisms (MDRO) frequently precedes infection among patients in the intensive care unit (ICU), although the dynamics of colonization are not completely understood. We performed a systematic review and meta-analysis of ICU studies which described the cumulative incidence and rates of MDRO gut acquisition.

METHODS

We systematically searched PubMed, Embase, and Web of Science for studies published from 2010 to 2023 reporting on gut acquisition of MDRO in the ICU. MDRO were defined as multidrug resistant non-Pseudomonas Gram-negative bacteria (NP-GN), Pseudomonas spp., and vancomycin-resistant Enterococcus (VRE). We included observational studies which obtained perianal or rectal swabs at ICU admission (within 48 h) and at one or more subsequent timepoints. Our primary outcome was the incidence rate of gut acquisition of MDRO, defined as any MDRO newly detected after ICU admission (i.e., not present at baseline) for all patient-time at risk. The study was registered with PROSPERO, CRD42023481569.

RESULTS

Of 482 studies initially identified, 14 studies with 37,305 patients met criteria for inclusion. The pooled incidence of gut acquisition of MDRO during ICU hospitalization was 5% (range: 1-43%) with a pooled incidence rate of 12.2 (95% CI 8.1-18.6) per 1000 patient-days. Median time to acquisition ranged from 4 to 26 days after ICU admission. Results were similar for NP-GN and Pseudomonas spp., with insufficient data to assess VRE. Among six studies which provided sufficient data to perform curve fitting, there was a quasi-linear increase in gut MDRO colonization of 1.41% per day which was stable through 30 days of ICU hospitalization (R2 = 0.50, p < 0.01).

CONCLUSIONS

Acquisition of gut MDRO was common in the ICU and increases with days spent in ICU through 30 days of follow-up. These data may guide future interventions seeking to prevent gut acquisition of MDRO in the ICU.

Probiotic potential of Streptomyces levis strain HFM-2 isolated from human gut and its antibiofilm properties against pathogenic bacteria

BACKGROUND

Antimicrobial resistance (AMR) is a serious worldwide public health concern that needs immediate action. Probiotics could be a promising alternative for fighting antibiotic resistance, displaying beneficial effects to the host by combating diseases, improving growth, and stimulating the host immune responses against infection. This study was conducted to evaluate the probiotic, antibacterial, and antibiofilm potential of Streptomyces levis strain HFM-2 isolated from the healthy human gut.

RESULTS

In vitro antibacterial activity in the cell-free supernatant of S. levis strain HFM-2 was evaluated against different pathogens viz. K. pneumoniae sub sp. pneumoniae, S. aureus, B. subtilis, VRE, S. typhi, S. epidermidis, MRSA, V. cholerae, M. smegmatis, E. coli, P. aeruginosa and E. aerogenes. Further, the ethyl acetate extract from S. levis strain HFM-2 showed strong biofilm inhibition against S. typhi, K. pneumoniae sub sp. pneumoniae, P. aeruginosa and E. coli. Fluorescence microscopy was used to detect biofilm inhibition properties. MIC and MBC values of EtOAc extract were determined at 500 and 1000 µg/mL, respectively. Further, strain HFM-2 showed high tolerance in gastric juice, pancreatin, bile, and at low pH. It exhibited efficient adhesion properties, displaying auto-aggregation (97.0%), hydrophobicity (95.71%, 88.96%, and 81.15% for ethyl acetate, chloroform and xylene, respectively), and showed 89.75%, 86.53%, 83.06% and 76.13% co-aggregation with S. typhi, MRSA, S. pyogenes and E. coli, respectively after 60 min of incubation. The S. levis strain HFM-2 was susceptible to different antibiotics such as tetracycline, streptomycin, kanamycin, ciprofloxacin, erythromycin, linezolid, meropenem, amikacin, gentamycin, clindamycin, moxifloxacin and vancomycin, but resistant to ampicillin and penicillin G.

CONCLUSION

The study shows that S. levis strain HFM-2 has significant probiotic properties such as good viability in bile, gastric juice, pancreatin environment, and at low pH; proficient adhesion properties, and antibiotic susceptibility. Further, the EtOAc extract of Streptomyces levis strain HFM-2 has a potent antibiofilm and antibacterial activity against antibacterial-resistant clinical pathogens.

Decolonization and Pathogen Reduction Approaches to Prevent Antimicrobial Resistance and Healthcare-Associated Infections

Antimicrobial resistance in healthcare-associated bacterial pathogens and the infections they cause are major public health threats affecting nearly all healthcare facilities. Antimicrobial-resistant bacterial infections can occur when colonizing pathogenic bacteria that normally make up a small fraction of the human microbiota increase in number in response to clinical perturbations. Such infections are especially likely when pathogens are resistant to the collateral effects of antimicrobial agents that disrupt the human microbiome, resulting in loss of colonization resistance, a key host defense. Pathogen reduction is an emerging strategy to prevent transmission of, and infection with, antimicrobial-resistant healthcare-associated pathogens. We describe the basis for pathogen reduction as an overall prevention strategy, the evidence for its effectiveness, and the role of the human microbiome in colonization resistance that also reduces the risk for infection once colonized. In addition, we explore ideal attributes of current and future pathogen-reducing approaches.

The role of centre and country factors on process and outcome indicators in critically ill patients with hospital-acquired bloodstream infections

PURPOSE

The primary objective of this study was to evaluate the associations between centre/country-based factors and two important process and outcome indicators in patients with hospital-acquired bloodstream infections (HABSI).

METHODS

We used data on HABSI from the prospective EUROBACT-2 study to evaluate the associations between centre/country factors on a process or an outcome indicator: adequacy of antimicrobial therapy within the first 24 h or 28-day mortality, respectively. Mixed logistical models with clustering by centre identified factors associated with both indicators.

RESULTS

Two thousand two hundred nine patients from two hundred one intensive care units (ICUs) were included in forty-seven countries. Overall, 51% (n = 1128) of patients received an adequate antimicrobial therapy and the 28-day mortality was 38% (n = 839). The availability of therapeutic drug monitoring (TDM) for aminoglycosides everyday [odds ratio (OR) 1.48, 95% confidence interval (CI) 1.03-2.14] or within a few hours (OR 1.79, 95% CI 1.34-2.38), surveillance cultures for multidrug-resistant organism carriage performed weekly (OR 1.45, 95% CI 1.09-1.93), and increasing Human Development Index (HDI) values were associated with adequate antimicrobial therapy. The presence of intermediate care beds (OR 0.63, 95% CI 0.47-0.84), TDM for aminoglycoside available everyday (OR 0.66, 95% CI 0.44-1.00) or within a few hours (OR 0.51, 95% CI 0.37-0.70), 24/7 consultation of clinical pharmacists (OR 0.67, 95% CI 0.47-0.95), percentage of vancomycin-resistant enterococci (VRE) between 10% and 25% in the ICU (OR 1.67, 95% CI 1.00-2.80), and decreasing HDI values were associated with 28-day mortality.

CONCLUSION

Centre/country factors should be targeted for future interventions to improve management strategies and outcome of HABSI in ICU patients.

Copper peroxide nanodot-decorated gold nanostar/silica nanorod Janus nanostructure with NIR-II photothermal and acid-triggered hydroxyl radical generation properties for the effective treatment of wound infections

Recently, bacterial infections have become a global crisis, greatly threatening the health of human beings. The development of a non-antibiotic biomaterial is recognized as an alternative way for the effective treatment of bacterial infections. In the present work, a multifunctional copper peroxide (CP) nanodot-decorated gold nanostar (GNS)/silica nanorod (SiNR) Janus nanostructure (GNS@CP/SiNR) with excellent antibacterial activity was reported. Due to the formation of the Janus nanostructure, GNS@CP/SiNR displayed strong plasmonic resonance absorbance in the near infrared (NIR)-II region that enabled the nanosystem to achieve mild photothermal therapy (MPTT). In acidic conditions, CP decorated on GNS@CP/SiNR dissociated rapidly by releasing Cu2+ and H2O2, which subsequently transformed to ˙OH via the Fenton-like reaction for chemodynamic therapy (CDT). As a result, GNS@CP/SiNR could effectively inhibit both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), and eradicate the associated bacterial biofilms by exerting the synergistic MPTT/CDT antibacterial effect. Moreover, GNS@CP/SiNR was also demonstrated to be effective in treating wound infections, as verified on the S. aureus-infected full thickness excision wound rat model. Our mechanism study revealed that the synergistic MPTT/CDT effect of GNS@CP/SiNR firstly caused bacterial membrane damage, followed by boosting intracellular ROS via the severe oxidative stress effect, which subsequently caused the depletion of intracellular GSH and DNA damage, finally leading to the death of bacteria.

Impact of preoperative infection on the outcomes of liver transplant recipients: a national propensity score-matched retrospective cohort study in China

BACKGROUND

Impact of preoperative infection on liver transplantation (LT) needs further investigation.

MATERIALS AND METHODS

From January 1, 2015 to December 31, 2022, 24,122 eligible patients receiving LT were enrolled from the China Liver Transplant Registry database. The outcomes of LT were compared after using the propensity score-matched analysis.

RESULTS

Compared to the non-infection group, patients in the infection group were more likely to have postoperative effusion, infection, abdominal bleeding and biliary complications (all P<0.01), and they had shorter 30-day, 90-day survival and overall survival (OS) (all P<0.01). Cox proportional hazards regression analysis revealed that MELD score and cold ischemia time were risk factors for the OS in the infection group (both P<0.05). Besides, compared to the non-pulmonary group, patients in the pulmonary group were more likely to have postoperative effusion and infection (both P<0.0001), and less likely to have postoperative abscess and early allograft dysfunction (both P<0.05). Patients in the non-abdominal group also had a higher proportion of postoperative infection than those in the abdominal group (P<0.05). Furthermore, compared to the number=1 group, patients in the number≥2 group were more prone to postoperative effusion and infection (both P<0.01), and they also had shorter 30-day and 90-day survival (both P<0.05).

CONCLUSION

Preoperative infection can result in a higher incidence of early postoperative complications and shorter survival in liver transplant recipients. The types and number of infection sites will also influence the prognosis of liver transplant recipients.

Clinical and Genomic Characterization of a Cohort of Patients With Klebsiella pneumoniae Bloodstream Infection

BACKGROUND

The clinical and microbial factors associated with Klebsiella pneumoniae bloodstream infections (BSIs) are not well characterized. Prior studies have focused on highly resistant or hypervirulent isolates, limiting our understanding of K. pneumoniae strains that commonly cause BSI. We performed a record review and whole-genome sequencing to investigate the clinical characteristics, bacterial diversity, determinants of antimicrobial resistance, and risk factors for in-hospital death in a cohort of patients with K. pneumoniae BSI.

METHODS

We identified 562 patients at Massachusetts General Hospital with K. pneumoniae BSIs between 2016 and 2022. We collected data on comorbid conditions, infection source, clinical outcomes, and antibiotic resistance and performed whole-genome sequencing on 108 sequential BSI isolates from 2021 to 2022.

RESULTS

Intra-abdominal infection was the most common source of infection accounting for 34% of all BSIs. A respiratory tract source accounted for 6% of BSIs but was associated with a higher in-hospital mortality rate (adjusted odds ratio, 5.4 [95% confidence interval, 2.2-12.8]; P < .001 for comparison with other sources). Resistance to the first antibiotic prescribed was also associated with a higher risk of death (adjusted odds ratio, 5.2 [95% confidence interval, 2.2-12.4]; P < .001). BSI isolates were genetically diverse, and no clusters of epidemiologically and genetically linked cases were observed. Virulence factors associated with invasiveness were observed at a low prevalence, although an unexpected association between O-antigen type and the source of infection was found.

CONCLUSIONS

These observations demonstrate the versatility of K. pneumoniae as an opportunistic pathogen and highlight the need for new approaches for surveillance and the rapid identification of patients with invasive antimicrobial-resistant K. pneumoniae infection.

The epidemiology of multidrug-resistant organisms in persons diagnosed with cancer in Norway, 2008-2018: expanding surveillance using existing laboratory and register data

Surveillance has revealed an increase of multidrug-resistant organisms (MDROs), even in low-prevalent settings such as Norway. MDROs pose a particular threat to at-risk populations, including persons with cancer. It is necessary to include such populations in future infection surveillance. By combining existing data sources, we aimed to describe the epidemiology of MDROs in persons diagnosed with cancer in Norway from 2008 to 2018. A cohort was established using data from the Cancer Registry of Norway, which was then linked to notifications of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin- and/or linezolid-resistant enterococci (V/LRE), and carbapenemase-producing Gram-negative bacilli (CP-GNB) from the Norwegian Surveillance System for Communicable Diseases, and laboratory data on third-generation cephalosporin-resistant Enterobacterales (3GCR-E) from Oslo University Hospital (OUH). We described the incidence of MDROs and resistance proportion in Enterobacterales from 6 months prior to the person's first cancer diagnosis and up to 3 years after. The cohort included 322,005 persons, of which 0.3% (878) were diagnosed with notifiable MDROs. Peak incidence rates per 100,000 person-years were 60.9 for MRSA, 97.2 for V/LRE, and 6.8 for CP-GNB. The proportion of 3GCR-E in Enterobacterales in blood or urine cultures at OUH was 6% (746/12,534). Despite overall low MDRO incidence, there was an unfavourable trend in the incidence and resistance proportion of Gram-negative bacteria. To address this, there is a need for effective infection control and surveillance. Our study demonstrated the feasibility of expanding the surveillance of MDROs and at-risk populations through the linkage of existing laboratory and register data.

Current practice of screening and antimicrobial prophylaxis to prevent Gram-negative bacterial infection in high-risk haematology patients: results from a pan-European survey

Background

Bacterial infections frequently occur in haematological patients, especially during prolonged neutropenia after intensive chemotherapy, often leading to bloodstream infections and pneumonia.

Objective

Routine antimicrobial prophylaxis (AMP) for high-risk haematology patients is still debated while prevalence of multi-drug resistant (MDR) Gram-negative bacteria (GNB) is rising globally. We aimed to assess the current practice of AMP in this population.

Design

Cross-sectional observational survey study.

Methods

Haematologists and infectious diseases physicians Europewide were invited to an online survey including questions on routine screening for GNB, incidence of MDR-GNB colonization, antimicrobial prophylaxis practices, rates of bloodstream infections (BSI), ICU admission and mortality differentiated by infections due to GNB versus MDR-GNB.

Results

120 haematology centres from 28 countries participated. Screening for MDR-GNB is performed in 86.7% of centres, mostly via rectal swabs (58.3%). In 39.2% of routine AMP is used, mostly with fluoroquinolones. Estimates of GNB-BSI yielded higher rates in patients not receiving anti-GNB prophylaxis than in those who do for E. coli (10% vs 7%) Klebsiella spp. (10% vs 5%), and Pseudomonas spp. (5% vs 4%). Rates for MDR-GNB infection were estimated lower in centres that administer AMP for MDR E. coli (5% vs 3%) Klebsiella spp. (5% vs 3%), and Pseudomonas spp. (2% vs 1%). In an exploratory analysis, Southern and Eastern European countries expected higher rates of MDR-GNB infections with lower ICU admission and mortality rates which may be subject to estimation bias.

Conclusion

Screening for MDR-GNB is frequently performed. AMP against GNB infections is still often implemented. Estimated BSI rates are rather low, while the rate of MDR-GNB infections rises. Tailored prophylaxis including antimicrobial stewardship becomes more important.

Colonization of multidrug-resistant Gram-negative bacteria increases risk of surgical site infection after hemorrhoidectomy: a cross-sectional study of two centers in southern China

PURPOSE

The present study aims to determine the rectoanal colonization rate and risk factors for the colonization of present multidrug-resistant bacteria (MDRBs). In addition, the relationship between MDRB colonization and surgical site infection (SSI) following hemorrhoidectomy was explored.

METHODS

A cross-sectional study was conducted in the Department of Colorectal Surgery of two hospitals. Patients with hemorrhoid disease, who underwent hemorrhoidectomy, were included. The pre-surgical screening of multidrug-resistant Gram-negative bacteria (MDR-GNB) colonization was performed using rectal swabs on the day of admission. Then, the MDRB colonization rate was determined through the rectal swab. Logistic regression models were established to determine the risk factors for MDRB colonization and SSI after hemorrhoidectomy. A p-value of < 0.05 was considered statistically significant.

RESULTS

A total of 432 patients met the inclusion criteria, and the MDRB colonization prevalence was 21.06% (91/432). The independent risk factors for MDRB colonization were as follows: patients who received ≥ 2 categories of antibiotic treatment within 3 months (odds ratio (OR): 3.714, 95% confidence interval (CI): 1.436-9.605, p = 0.007), patients with inflammatory bowel disease (IBD; OR: 6.746, 95% CI: 2.361-19.608, p < 0.001), and patients with high serum uric acid (OR: 1.006, 95% CI: 1.001-1.010, p = 0.017). Furthermore, 41.57% (37/89) of MDRB carriers and 1.81% (6/332) of non-carriers developed SSIs, with a total incidence of 10.21% (43/421). Based on the multivariable model, the rectoanal colonization of MDRBs (OR: 32.087, 95% CI: 12.052-85.424, p < 0.001) and hemoglobin < 100 g/L (OR: 4.130, 95% CI: 1.556-10.960, p = 0.004) were independently associated with SSI after hemorrhoidectomy.

CONCLUSION

The rectoanal colonization rate of MDRBs in hemorrhoid patients is high, and this was identified as an independent risk factor for SSI after hemorrhoidectomy.

Characterization of Vancomycin Resistant Enterococci and Drug Ligand Interaction between vanA of E. faecalis with the Bio-Compounds from Aegles marmelos

Objectives

Enterococcus faecalis is a gram positive diplococci, highly versatile and a normal commensal of the gut microbiome. Resistance to vancomycin is a serious issue in various health-care setting exhibited by vancomycin resistant Enterococci (VRE) due to the alteration in the peptidoglycan synthesis pathway. This study is thus aimed to detect the VRE from the patients with root caries from the clinical isolates of E. faecalis and to evaluate the in-silico interactions between vanA and the Aegles marmelos bio-compounds.

Methods

E. faecalis was phenotypically characterized from 20 root caries samples and the frequency of vanA and vanB genes was detected by polymerase chain reaction (PCR). Further crude methanolic extracts from the dried leaves of A. marmelos was assessed for its antimicrobial activity. This is followed by the selection of five A. marmelos bio-compounds for the computational approach towards the drug ligand interactions.

Results

12 strains (60%) of E. faecalis was identified from the root caries samples and vanA was detected from two strains (16%). Both the stains showed the presence of vanA and none of the strains possessed vanB. Crude extract of A. marmelos showed promising antibacterial activity against the VRE strains. In-silico analysis of the A. marmelos bio-compounds revealed Imperatonin as the best compound with high docking energy (-8.11) and hydrogen bonds with < 140 TPSA (Topological polar surface area) and zero violations.

Conclusion

The present study records the VRE strains among the root caries with imperatorin from A. marmelos as a promising drug candidate. However the study requires further experimentation and validation.

Trends in Antibiotic-Resistant Bacteria Isolated from Screening Clinical Samples in a Tertiary Care Hospital over the 2018-2022 Period

To assess the putative impact of the COVID-19 pandemic on multidrug-resistant (MDR) bacteria recovered from routine screening samples and, more globally, the trends in time to first positive screening sample and carriage duration of those bacteria in patients admitted to a tertiary hospital, data from laboratory results were retrospectively mined over the 2018-2022 period. No significant differences could be found in the number of positive patients or MDR isolates per year, time to positive screening, or carriage duration. Extended-spectrum beta-lactamase producers were dominant throughout the studied period but their relative proportion decreased over time as well as that of meticillin-resistant Staphylococcus aureus. Meanwhile, carbapenemase-producing enterobacteria (CPE) proportion increased. Among the 212 CPE isolates, Klebsiella pneumoniae and Escherichia coli were the more frequent species but, beginning in 2020, a significant rise in Enterobacter cloacae complex and Citrobacter freundii occurred. OXA48 was identified as the leading carbapenemase and, in 2020, a peak in VIM-producing enterobacteria linked to an outbreak of E. cloacae complex during the COVID-19 pandemic was singled out. Finally, a worrisome rise in isolates producing multiple carbapenemases (NDM/VIM and mostly NDM/OXA48) was highlighted, especially in 2022, which could lead to therapeutic dead-ends if their dissemination is not controlled.

An overview of novel antimicrobial carbonic anhydrase inhibitors

INTRODUCTION

Four different genetic families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) are present in bacteria, α-, β-, γ- and ι-CAs. They play relevant functions related to CO2, HCO3-/H+ ions homeostasis, being involved in metabolic biosynthetic pathways, pH regulation, and represent virulence and survival factors for bacteria in various niches. Bacterial CAs started to be considered druggable targets in the last decade, as their inhibition impairs survival, growth, and virulence of these pathogens.

AREAS COVERED

Significant advances were registered in the last years for designing effective inhibitors of sulfonamide type for Helicobacter pylori α-CA, Neisseria gonorrhoeae α-CA, vacomycin-resistant enterococci (VRE) α- and γ-CAs, for which the in vivo validation has also been achieved. MIC-s in the range of 0.25-4.0 µg/mL for wild type and drug resistant N. gonorrhoeae strains, and of 0.007-2.0 µg/mL for VRE were observed for some 1,3,4-thiadiazole-2-sulfonamides, and acetazolamide was effective in gut decolonization from VRE.

EXPERT OPINION

Targeting bacterial CAs from other pathogens, among which Vibrio cholerae, Mycobacterium tuberculosis, Brucella suis, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Porphyromonas gingivalis, Clostridium perfringens, Streptococcus mutans, Burkholderia pseudomallei, Francisella tularensis, Escherichia coli, Mammaliicoccus (Staphylococcus) sciuri, Pseudomonas aeruginosa, may lead to novel antibacterials devoid of drug resistance problems.

An Economic Evaluation Estimating the Clinical and Economic Burden of Increased Vancomycin-Resistant Enterococcus faecium Infection Incidence in Japan

INTRODUCTION

While incidence rates of vancomycin-resistant Enterococcus faecium have remained comparatively low in Japan, there have been increasing reports of more vancomycin-resistant Enterococcus (VRE) outbreaks, requiring costly measures to contain. Increased incidence of VRE in Japan may lead to more frequent and harder to contain outbreaks with current control measures, causing a significant burden to the healthcare system in Japan. This study aimed to demonstrate the clinical and economic burden of vancomycin-resistant E. faecium infections to the Japanese healthcare system and the impact of increasing rates of vancomycin resistance.

METHODS

A de novo deterministic analytic model was developed to assess the health economic outcomes of treating hospital-acquired VRE infections; patients are treated according to a two-line treatment strategy, dependent on their resistance status. The model considers hospitalisation costs and the additional cost of infection control. Scenarios investigated the current burden of VRE infections and the additional burden of increased incidence of VRE. Outcomes were assessed over a 1-year and 10-year time horizon from a healthcare payer's perspective in a Japanese setting. Quality-adjusted life years (QALYs) were valued with a willingness-to-pay threshold of ¥5,000,000 ($38,023), and costs and benefits were discounted at a rate of 2%.

RESULTS

Current VRE incidence levels in enterococcal infections in Japan equates to ¥130,209,933,636 ($996,204,669) in associated costs and a loss of 185,361 life years (LYs) and 165,934 QALYs over 10 years. A three-fold increase (1.83%) is associated with an additional ¥4,745,059,504 ($36,084,651) in total costs on top of the current cost burden as well as an additional loss of 683 LYs over a lifetime, corresponding to 616 QALYs lost.

CONCLUSION

Despite low incidence rates, VRE infections already represent a substantial economic burden to the Japanese healthcare system. The substantial increase in costs associated with a higher incidence of VRE infections could result in a significant economic challenge for Japan.

Modulation of the Gut Microbiota to Control Antimicrobial Resistance (AMR)-A Narrative Review with a Focus on Faecal Microbiota Transplantation (FMT)

Antimicrobial resistance (AMR) is one of the greatest challenges facing humanity, causing a substantial burden to the global healthcare system. AMR in Gram-negative organisms is particularly concerning due to a dramatic rise in infections caused by extended-spectrum beta-lactamase and carbapenemase-producing Enterobacterales (ESBL and CPE). These pathogens have limited treatment options and are associated with poor clinical outcomes, including high mortality rates. The microbiota of the gastrointestinal tract acts as a major reservoir of antibiotic resistance genes (the resistome), and the environment facilitates intra and inter-species transfer of mobile genetic elements carrying these resistance genes. As colonisation often precedes infection, strategies to manipulate the resistome to limit endogenous infections with AMR organisms, as well as prevent transmission to others, is a worthwhile pursuit. This narrative review presents existing evidence on how manipulation of the gut microbiota can be exploited to therapeutically restore colonisation resistance using a number of methods, including diet, probiotics, bacteriophages and faecal microbiota transplantation (FMT).

What to Do with the New Antibiotics?

Multidrug-resistant Gram-negative bacteria-related infections have become a real public health problem and have exposed the risk of a therapeutic impasse. In recent years, many new antibiotics have been introduced to enrich the therapeutic armamentarium. Among these new molecules, some are mainly of interest for the treatment of the multidrug-resistant infections associated with Pseudomonas aeruginosa (ceftolozane/tazobactam and imipenem/relebactam); others are for carbapenem-resistant infections associated with Enterobacterales (ceftazidime/avibactam, meropenem/vaborbactam); and finally, there are others that are effective on the majority of multidrug-resistant Gram-negative bacilli (cefiderocol). Most international guidelines recommend these new antibiotics in the treatment of microbiologically documented infections. However, given the significant morbidity and mortality of these infections, particularly in the case of inadequate therapy, it is important to consider the place of these antibiotics in probabilistic treatment. Knowledge of the risk factors for multidrug-resistant Gram-negative bacilli (local ecology, prior colonization, failure of prior antibiotic therapy, and source of infection) seems necessary in order to optimize antibiotic prescriptions. In this review, we will assess these different antibiotics according to the epidemiological data.