Potential burden of antibiotic resistance on surgery and cancer chemotherapy antibiotic prophylaxis in the USA: a literature review and modelling study

Preventing Surgical Site Infections in the Era of Escalating Antibiotic Resistance and Antibiotic Stewardship

Importance

According to the Centers for Disease Control and Prevention and governing bodies within the American College of Surgeons, the administration of antibiotics as prophylaxis against infection prior to a planned elective procedure is, with rare exception, routinely recommended. The goal of "getting to zero" infections remains a high priority for policymakers, practitioners, and certainly for patients.

Observations

Despite the many advances in surgical technique, skin decontamination, sterile procedure, and enhanced recovery programs, surgical site infections continue to adversely affect procedures as diverse as dental implant surgery, joint arthroplasty, and major abdominal surgery. Although surgical site infection rates are at historically low levels, progress has stalled in recent reporting periods and such infections remain disabling, costly, and occasionally lethal. Stakeholders in the field, including surgeons, infectious diseases specialists, and industry, advocate for strategies emphasizing greater levels of intraoperative sterility or broader-spectrum antibiotic coverage as the most appropriate path forward.

Conclusions and Relevance

The current emphasis on ever-increasing levels of intraoperative sterility and extended-spectrum antibiotic use are not sustainable long-term solutions. Continuing to escalate these approaches may contribute to unintended consequences including antimicrobial resistance. Principles of antimicrobial stewardship and microbiome sciences can be applied to inform a more effective and sustainable approach to infection prevention in the field of surgery.

Investigation of antimicrobial susceptibility patterns, risk factors and their impact on mortality in cancer patients at a tertiary care cancer hospital- A prospective study

BACKGROUND

Cancer patients are vulnerable to infections due to immunosuppression caused by cancer itself and its treatment. The emergence of antimicrobial-resistant bacteria further complicates the treatment of infections and increases the mortality and hospital stays. This study aimed to investigate the microbial spectrum, antimicrobial resistance patterns, risk factors, and their impact on clinical outcomes in these patients.

METHODS

A prospective study was conducted at a tertiary care cancer hospital in Patna, Bihar, India, which included cancer patients aged 18 years and older with positive microbial cultures.

RESULTS

This study analysed 440 patients, 53% (234) of whom were females, with an average age of 49.27 (± 14.73) years. A total of 541 isolates were identified, among which 48.01% (242) were multidrug resistant (MDR), 29.76% (150) were extensively drug resistant (XDR), and 19.84% (112) were sensitive. This study revealed that patients who underwent surgery, chemotherapy, were hospitalized, had a history of antibiotic exposure, and had severe neutropenia were more susceptible to MDR and XDR infections. The average hospital stays were 16.90 (± 10.23), 18.30 (± 11.14), and 22.83 (± 13.22) days for patients with sensitive, MDR, and XDR infections, respectively. The study also revealed overall 30-day mortality rate of 31.81% (140), whereas the MDR and XDR group exhibited 38.92% and 50.29% rates of 30-day mortality respectively (P < 0.001). Possible risk factors identified that could lead to mortality, were cancer recurrence, sepsis, chemotherapy, indwelling invasive devices such as foley catheter, Central venous catheter and ryles tube, MASCC score (< 21) and pneumonia.

CONCLUSIONS

This study emphasizes the necessity for personalized interventions among cancer patients, such as identifying patients at risk of infection, judicious antibiotic use, infection control measures, and the implementation of antimicrobial stewardship programs to reduce the rate of antimicrobial-resistant infection and associated mortality and hospital length of stay.

The scope of the antimicrobial resistance challenge

Each year, an estimated 7·7 million deaths are attributed to bacterial infections, of which 4.95 million are associated with drug-resistant pathogens, and 1·27 million are caused by bacterial pathogens resistant to the antibiotics available. Access to effective antibiotics when indicated prolongs life, reduces disability, reduces health-care expenses, and enables access to other life-saving medical innovations. Antimicrobial resistance undoes these benefits and is a major barrier to attainment of the Sustainable Development Goals, including targets for newborn survival, progress on healthy ageing, and alleviation of poverty. Adverse consequences from antimicrobial resistance are seen across the human life course in both health-care-associated and community-associated infections, as well as in animals and the food chain. The small set of effective antibiotics has narrowed, especially in resource-poor settings, and people who are very young, very old, and severely ill are particularly susceptible to resistant infections. This paper, the first in a Series on the challenge of antimicrobial resistance, considers the global scope of the problem and how it should be measured. Robust and actionable data are needed to drive changes and inform effective interventions to contain resistance. Surveillance must cover all geographical regions, minimise biases towards hospital-derived data, and include non-human niches.

Cell membrane-coated nanoparticles for targeting carcinogenic bacteria

The etiology of cancers is multifactorial, with certain bacteria established as contributors to carcinogenesis. As the understanding of carcinogenic bacteria deepens, interest in cancer treatment through bacterial eradication is growing. Among emerging antibacterial platforms, cell membrane-coated nanoparticles (CNPs), constructed by enveloping synthetic substrates with natural cell membranes, exhibit significant promise in overcoming challenges encountered by traditional antibiotics. This article reviews recent advancements in developing CNPs for targeting carcinogenic bacteria. It first summarizes the mechanisms of carcinogenic bacteria and the status of cancer treatment through bacterial eradication. Then, it reviews engineering strategies for developing highly functional and multitasking CNPs and examines the emerging applications of CNPs in combating carcinogenic bacteria. These applications include neutralizing virulence factors to enhance bacterial eradication, exploiting bacterium-host binding for precise antibiotic delivery, and modulating antibacterial immunity to inhibit bacterial growth. Overall, this article aims to inspire technological innovations in developing CNPs for effective cancer treatment through oncogenic bacterial targeting.

Arginine and tryptophan-rich dendritic antimicrobial peptides that disrupt membranes for bacterial infection in vivo

The potent antibacterial activity and low resistance of antimicrobial peptides (AMPs) render them potential candidates for treating multidrug-resistant bacterial infections. Herein, a minimalist design strategy was proposed employing the "golden partner" combination of arginine (R) and tryptophan (W), along with a dendritic structure to design AMPs. By extension, the α/ε-amino group and the carboxyl group of lysine (K) were utilized to link R and W, forming dendritic peptide templates αRn(εRn)KWm-NH2 and αWn(εWn)KRm-NH2, respectively. The corresponding linear peptide templates R2nKWm-NH2 and W2nKRm-NH2 were used as controls. Their physicochemical properties, activity, toxicity, and stability were compared. Among these new peptides, the dendritic peptide R2(R2)KW4 was screened as a prospective candidate owing to its preferable antibacterial properties, biocompatibility, and stability. Additionally, R2(R2)KW4 not only effectively restrained the progression of antibiotic resistance, but also demonstrated synergistic utility when combined with conventional antibiotics due to its unique membrane-disruptive mechanism. Furthermore, R2(R2)KW4 possessed low toxicity (LD50 = 109.31 mg/kg) in vivo, while efficiently clearing E. coli in pulmonary-infected mice. In conclusion, R2(R2)KW4 has the potential to become an antimicrobial regent or adjuvant, and the minimalist design strategy of dendritic peptides provides innovative and encouraging thoughts in designing AMPs.

Contribution of the patient microbiome to surgical site infection and antibiotic prophylaxis failure in spine surgery

Despite modern antiseptic techniques, surgical site infection (SSI) remains a leading complication of surgery. However, the origins of SSI and the high rates of antimicrobial resistance observed in these infections are poorly understood. Using instrumented spine surgery as a model of clean (class I) skin incision, we prospectively sampled preoperative microbiomes and postoperative SSI isolates in a cohort of 204 patients. Combining multiple forms of genomic analysis, we correlated the identity, anatomic distribution, and antimicrobial resistance profiles of SSI pathogens with those of preoperative strains obtained from the patient skin microbiome. We found that 86% of SSIs, comprising a broad range of bacterial species, originated endogenously from preoperative strains, with no evidence of common source infection among a superset of 1610 patients. Most SSI isolates (59%) were resistant to the prophylactic antibiotic administered during surgery, and their resistance phenotypes correlated with the patient's preoperative resistome (P = 0.0002). These findings indicate the need for SSI prevention strategies tailored to the preoperative microbiome and resistome present in individual patients.

Antibiotic Stewardship in Surgical Departments

Antimicrobial resistance (AMR) has emerged as one of the leading public health threats of the 21st century. New evidence underscores its significance in patients' morbidity and mortality, length of stay, as well as healthcare costs. Globally, the factors that contribute to antimicrobial resistance include social and economic determinants, healthcare governance, and environmental interactions with impact on humans, plants, and animals. Antimicrobial stewardship (AS) programs have historically overlooked surgical teams as they considered them more difficult to engage. This review aims to summarize the evolution and significance of AS in surgical wards, including the surgical intensive care unit (SICU) and the role of diagnostic stewardship (DS). The contribution of AS team members is presented. The new diagnostic modalities and the new technologies including artificial intelligence (AI) are also reviewed.

Estimating the Treatment and Prophylactic Economic Value of New Antimicrobials in Managing Antibiotic Resistance and Serious Infections for Common Pathogens in the USA: A Population Modelling Study

BACKGROUND

Antimicrobial resistance is a growing public health concern. There is a global need to estimate the population-level value of developing new antimicrobials and to ensure the effective use of existing antimicrobials as strategies to counteract antimicrobial resistance. To this aim, population-level value criteria need to be considered alongside conventional value measures.

OBJECTIVE

The objective of this study was to develop a novel modelling approach to estimate the value of new antimicrobials, considering the transmission, diversity and enablement elements of STEDI value.

METHODS

We developed a population-based mathematical model for the assessment of antimicrobial value considering both prophylactic use of antimicrobials and the treatment of selected serious hospital-acquired infections in hospitals in the USA at a population level. Large-scale clinical and population healthcare data were used to inform a modelling-based analysis assessing the impact of introducing a new antimicrobial compared with continuing with no new antimicrobial, accounting for the transmission, diversity and enablement value of antimicrobial agents.

RESULTS

Over a 10-year period, the addition of a new antimicrobial as part of an antimicrobial stewardship strategy in the USA was estimated to result in a proportional reduction of 9.03% in projected antimicrobial resistance levels. This yielded an estimated reduction of $64.3 million in hospitalization costs and a gain of over 153,000 quality-adjusted life-years at an economic value of over $15.4 billion over 10 years. Considering input uncertainty, the estimate of monetary benefit ranged from $11.1 to $21.4 billion.

CONCLUSIONS

The use of a new antimicrobial for treatment and prophylactic indications yields considerable clinical and economic benefits including transmission diversity and enablement value. These findings may provide decision makers with important evidence to support investment in new antimicrobials and antimicrobial stewardship policy that address the patient, population and system burden associated with antimicrobial resistance.

Is antibiotic prophylaxis generally safe and effective in surgical and nonsurgical scenarios? Evidence from an umbrella review of randomized controlled trials

BACKGROUND

The authors aimed to comprehensively evaluate the efficacy and safety of antibiotic prophylaxis through surgical and nonsurgical scenarios and assess the strength of evidence.

MATERIALS AND METHODS

The authors performed an umbrella review of meta-analyses of randomized controlled trials (RCTs). An evidence map was created to summarize the absolute benefits of antibiotic prophylaxis in each scenario and certainty of evidence.

RESULTS

Seventy-five meta-analyses proved eligible with 725 RCTs and 78 clinical scenarios in surgical and medical prophylaxis. Of 119 health outcomes, 67 (56.3%) showed statistically significant benefits, 34 of which were supported by convincing or highly suggestive evidence from RCTs. For surgeries, antibiotic prophylaxis may minimize infection occurrences in most surgeries except Mohs surgery, simple hand surgery, herniorrhaphy surgery, hepatectomy, thyroid surgery, rhinoplasty, stented distal hypospadias repair, midurethral sling placement, endoscopic sinus surgery, and transurethral resection of bladder tumors with only low to very low certainty evidence. For nonsurgery invasive procedures, only low to very low certainty evidence showed benefits of antibiotic prophylaxis for cystoscopy, postoperative urinary catheterization, and urodynamic study. For medical prophylaxis, antibiotic prophylaxis showed greater benefits in nonemergency scenarios, in which patients were mainly with weakened immune systems, or at risk of recurrent chronic infections. Antibiotics prophylaxis may increase antibiotic resistance or other adverse events in most scenarios and reached significance in cystoscopy, afebrile neutropenia following chemotherapy and hematopoietic stem cell transplantation.

CONCLUSIONS

Antibiotic prophylaxis in surgical and nonsurgical scenarios is generally effective and seems independent of surgical cleanliness and urgency of diseases. Its safety is not well determined due to lack of available data. Nevertheless, the low quality of current evidence limits the external validity of these findings, necessitating clinicians to judiciously assess indications, balancing low infection rates with antibiotic-related side effects.

Systemic Antibiotic Use in Acute Irreversible Pulpitis: Evaluating Clinical Practices and Molecular Insights

This scoping review systematically evaluates the use of systemic antibiotics in treating acute irreversible pulpitis, integrating clinical practice patterns with recent molecular insights. We analyzed clinical evidence on antibiotic prescription trends among dental professionals and examined molecular research advancements in relation to pulpitis. This review is intended to bridge the gap between clinical practice and molecular research, guiding more evidence-based approaches to treating acute irreversible pulpitis. Electronic databases were searched for relevant articles published in English based on the objective of the review. A second search using all identified keywords and index terms was undertaken across all the included databases. In addition, a reference list of identified articles was searched. Studies including original research, systematic reviews, meta-analyses, clinical trials, and observational and retrospective studies, all written in English and published from 2010 onwards, were included, and an analysis of the text words contained in the titles and abstracts of the retrieved papers and of the index terms used to describe the articles was performed. A total of N = 53 articles were selected. Altogether, N = 43 (76.79%) articles were cross-sectional studies, N = 4 (11.11%) were systematic reviews, and N = 3 (5.36%) were guidelines. The most frequent level of evidence was level VI (N = 43 (76.79%). The mean percentage of dentists who prescribed antibiotics to treat acute irreversible pulpitis was 23.89 ± 23.74% (range: 0.05-75.7). Similarly, for specialists, it was 22.41 ± 15.64 (range 2.2-50.4), and the percentage for undergraduates was 17.52 ± 20.59 (range 0-62.6). The significant developments in research models for pulpitis research and the characterisation of biomarkers have led to better management strategies. Concurrently, significant advancements in molecular research provide new understandings of pulpitis, suggesting alternative therapeutic approaches. Although there are guidelines available, increased rates of antibiotic prescription are still prevalent around the globe.

Tailored Pre-Operative Antibiotic Prophylaxis to Prevent Post-Operative Surgical Site Infections in General Surgery

The average American today undergoes three inpatient and two outpatient surgical procedures during one's life, each of which carries with it a risk of post-operative infection. It has long been known that post-operative infections cause significant morbidity in the immediate peri-operative period, but recent evidence suggests that they can have long-term consequences as well, increasing a patient's risk of infectious complications in unrelated surgeries performed months or even years later. While there are several theories on the origin of this association, including bacterial colonization of a post-operative infectious wound site, antimicrobial resistance from curative courses of antibiotics, subclinical immunosuppression, or the creation of an inflammatory "pathobiome" following an infectious insult, it is ultimately still unclear why patients who experience a single post-operative infection seem to be at a significantly higher risk of experiencing subsequent ones. Regardless, this association has significant implications for the routine use of pre-operative antibiotic prophylaxis. Indeed, while the prescription of antibiotics pre-operatively has dramatically reduced the rate of post-operative infections, the chosen prophylaxis regimens are typically standardized according to national guidelines, are facing increasing antimicrobial resistance patterns, and have been unable to reduce the risk of post-operative infection to acceptably low levels for certain surgeries. As a result, some clinicians have speculated that tailoring pre-operative antibiotic prophylaxis according to a patient's prior infectious and operative history could improve efficacy and further reduce the rate of post-operative infections. The purpose of this review is to describe the evidence for the link between multiple post-operative infections and explore the efficacy of individualized pre-operative prophylaxis.

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.

Antibiotic prophylaxis after 48 h postoperatively are not associated with decreased surgical site infections and other healthcare associated infections in pancreatic surgery patients: a retrospective cohort study

BACKGROUND

It is controversial whether antibiotic should be used prophylactically 48 h after pancreatic surgery. Hence, the association of antibiotic prophylaxis (AP) after 48 h postoperatively with the incidence of surgical site infections (SSIs) and other healthcare-associated infections (HAIs) in patients receiving pancreatic surgery was evaluated.

METHODS

A retrospective cohort analysis was performed on 1073 patients who underwent pancreatic surgery. These patients were categorized into the non-AP after 48 h postoperatively group (n = 963) and the AP after 48 h postoperatively group (n = 110) based on whether or not they obtained AP from 48 h to 30 days after surgery. Outcomes included SSIs and other HAIs.

RESULTS

The incidence of SSIs in the non-AP after 48 h postoperatively group (98/963, 10.2%) was notably lower than that in the AP after 48 h postoperatively group (22/110, 20.0%) (P = 0.002). Other HAIs incidence was not significantly different between the non-AP after 48 h postoperatively group (77/963, 8.0%) and the AP after 48 h postoperatively group (11/110, 10.0%) (P = 0.468). Multiple regression analysis demonstrated that AP after 48 h postoperatively was a risk factor for SSIs (OR = 2.14, 95% CI 1.28-3.59) but not for other HAIs (OR = 1.24, 95% CI 0.63-2.42) after adjustment for age, gender, and diabetes. Subsequent to adjustment for all confounding factors, AP after 48 h postoperatively was not a influence factor for SSIs (OR = 2.13, 95% CI 0.76-5.99) and other HAIs (OR = 3.69, 95% CI 0.99-13.81).

CONCLUSIONS

AP after 48 h postoperatively following pancreatic surgery was not associated with the lower morbidity rate of SSIs and other HAIs. Nonetheless, this study may facilitate further development of strategies towards standardization of the duration of AP management of pancreatic surgery.

Wastewater treatment plants: The missing link in global One-Health surveillance and management of antibiotic resistance

INTRODUCTION

As a global public health crisis, antibiotic resistance (AR) should be monitored and managed under the One-Health concept according to the World Health Organization (WHO), considering the interconnection between humans, animals, and the environment. But this approach often remains focused on human health and rarely on the environment and its compartments, especially wastewater as the main AR receptor. Wastewater treatment plants (WWTPs) not only are not designed for reliving AR but also provide appropriate conditions for enhancing AR through different mechanisms.

METHODS

By reviewing the research-based statistics on the inclusion of WWTPs in the One-Health/AR program crisis, this paper highlights the importance of paying attention to these hotspots, at first. Also, the importance and technical roadmap for the application of WWTPs in both surveillance and management of AR were provided. The current position of these facilities was also evaluated using strengths, weaknesses, opportunities, and threats (SWOT) analysis. In the end, the concluding knowledge gaps and research needs for future investigations were presented.

RESULTS

Despite the fact that wastewater matrices are the hotspot for AR dissemination, WWTPs appear under-represented in One-Health/AR literature. So, of the 414434 articles retrieved for One-Health only 1.5% (n = 6321) focused on AR and about 0.04% (n = 158) on WWTPs. The potential of WWTPs inclusion in AR surveillance has been confirmed by several studies, however, when it comes to its inclusion for management of AR, more evidence should be presented, which confirmed by SWOT results.

DISCUSSION

As such, WWTPs simultaneously provide opportunities for AR surveillance as it is assumed that this medium can reflect the reality of the corresponding society, and for managing unexpected crises which could impact the public. Nonetheless, there are still numerous considerations to change WWTPs role from Achilles' heel to Ajax' shield, including strengthening the research-based knowledge and conducting both surveillance and management strategies of AR under One-Health concept (One-Health/AR) in a clear straightforward framework.

An Antibiotic-Loaded Silicone-Hydrogel Interpenetrating Polymer Network for the Prevention of Surgical Site Infections

Surgical site infections (SSIs) are among the most frequent healthcare-associated infections, resulting in high morbidity, mortality, and cost. While correct hygiene measures and prophylactic antibiotics are effective in preventing SSIs, even in modern healthcare settings where recommended guidelines are strictly followed, SSIs persist as a considerable problem that has proven hard to solve. Surgical procedures involving the implantation of foreign bodies are particularly problematic due to the ability of microorganisms to adhere to and colonize the implanted material and form resilient biofilms. In these cases, SSIs may develop even months after implantation and can be difficult to treat once established. Locally applied antibiotics or specifically engineered implant materials with built-in antibiotic-release properties may prevent these complications and, ultimately, require fewer antibiotics compared to those that are systemically administered. In this study, we demonstrated an antimicrobial material concept with intended use in artificial vascular grafts. The material is a silicone-hydrogel interpenetrating polymer network developed earlier for drug-release catheters. In this study, we designed the material for permanent implantation and tested the drug-loading and drug-release properties of the material to prevent the growth of a typical causative pathogen of SSIs, Staphylococcus aureus. The novelty of this study is demonstrated through the antimicrobial properties of the material in vitro after loading it with an advantageous combination, minocycline and rifampicin, which subsequently showed superiority over the state-of-the-art (Propaten) artificial graft material in a large-animal study, using a novel porcine tissue-implantation model.

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.

What Is the Role of the Gut in Wound Infections?

Emerging evidence suggest a major role for the gut microbiome in wound infections. A Trojan Horse mechanism of surgical site infections has been hypothesized to occur when pathogens in the gut, gums, and periodontal areas enter an immune cell and silently travel to the wound site where they release their infectious payload. Genetic tracking of microbes at the strain level is now possible with genetic sequencing techniques and can clarify the origin of microbes that cause wound infections. An emerging field of dietary prehabilitation to modulate the microbiome before surgery is being described to improve infection-related outcomes from surgery.

Exploring the views of infection consultants in England on a novel delinked funding model for antimicrobials: the SMASH study

Objectives

A novel 'subscription-type' funding model was launched in England in July 2022 for ceftazidime/avibactam and cefiderocol. We explored the views of infection consultants on important aspects of the delinked antimicrobial funding model.

Methods

An online survey was sent to all infection consultants in NHS acute hospitals in England.

Results

The response rate was 31.2% (235/753). Most consultants agreed the model is a welcome development (69.8%, 164/235), will improve treatment of drug-resistant infections (68.5%, 161/235) and will stimulate research and development of new antimicrobials (57.9%, 136/235). Consultants disagreed that the model would lead to reduced carbapenem use and reported increased use of cefiderocol post-implementation. The presence of an antimicrobial pharmacy team, requirement for preauthorization by infection specialists, antimicrobial stewardship ward rounds and education of infection specialists were considered the most effective antimicrobial stewardship interventions. Under the new model, 42.1% (99/235) of consultants would use these antimicrobials empirically, if risk factors for antimicrobial resistance were present (previous infection, colonization, treatment failure with carbapenems, ward outbreak, recent admission to a high-prevalence setting).Significantly higher insurance and diversity values were given to model antimicrobials compared with established treatments for carbapenem-resistant infections, while meropenem recorded the highest enablement value. Use of both 'subscription-type' model drugs for a wide range of infection sites was reported. Respondents prioritized ceftazidime/avibactam for infections by bacteria producing OXA-48 and KPC and cefiderocol for those producing MBLs and infections with Stenotrophomonas maltophilia, Acinetobacter spp. and Burkholderia cepacia.

Conclusions

The 'subscription-type' model was viewed favourably by infection consultants in England.

Rapid Assessment of Susceptibility of Bacteria and Erythrocytes to Antimicrobial Peptides by Single-Cell Impedance Cytometry

Antimicrobial peptides (AMPs) represent a promising class of compounds to fight antibiotic-resistant infections. In most cases, they kill bacteria by making their membrane permeable and therefore exhibit low propensity to induce bacterial resistance. In addition, they are often selective, killing bacteria at concentrations lower than those at which they are toxic to the host. However, clinical applications of AMPs are hindered by a limited understanding of their interactions with bacteria and human cells. Standard susceptibility testing methods are based on the analysis of the growth of a bacterial population and therefore require several hours. Moreover, different assays are required to assess the toxicity to host cells. In this work, we propose the use of microfluidic impedance cytometry to explore the action of AMPs on both bacteria and host cells in a rapid manner and with single-cell resolution. Impedance measurements are particularly well-suited to detect the effects of AMPs on bacteria, due to the fact that the mechanism of action involves perturbation of the permeability of cell membranes. We show that the electrical signatures of Bacillus megaterium cells and human red blood cells (RBCs) reflect the action of a representative antimicrobial peptide, DNS-PMAP23. In particular, the impedance phase at high frequency (e.g., 11 or 20 MHz) is a reliable label-free metric for monitoring DNS-PMAP23 bactericidal activity and toxicity to RBCs. The impedance-based characterization is validated by comparison with standard antibacterial activity assays and absorbance-based hemolytic activity assays. Furthermore, we demonstrate the applicability of the technique to a mixed sample of B. megaterium cells and RBCs, which paves the way to study AMP selectivity for bacterial versus eukaryotic cells in the presence of both cell types.

Structure-Activity Relationship Study of Antimicrobial Peptide PE2 Delivered Novel Linear Derivatives with Potential of Eradicating Biofilms and Low Incidence of Drug Resistance

The ongoing emergence of antibiotic-resistant pathogens had been dramatically stimulating and accelerating the need for new drugs. PE2 is a kind of cyclic lipopeptide with broad-spectrum antimicrobial activity. Herein, its structure-activity relationship was systematically investigated by employing 4 cyclic analogues and 23 linear analogues for the first time. The screened linear analogues 26 and 27 bearing different fatty acyls at N-termini and a Tyr residue at the 9th position had superior potency compared to the cyclic analogues and showed equivalent antimicrobial activity compared with PE2. Notably, 26 and 27 exhibited significant ability against multidrug-resistant bacteria, favorable resistance to protease, excellent performance against biofilm, low drug resistance, and high effectiveness against the mice pneumonia model. The antibacterial mechanisms of PE2 and linear derivatives 26 and 27 were also preliminarily explored in this study. As described above, 26 and 27 are promising antimicrobial candidates for the treatment of infections associated with drug-resistant bacteria.

The importance of targeting intraoperative transmission of bacteria with antibiotic resistance and strain characteristics

BACKGROUND

Evidence-based intraoperative infection control measures can reduce Staphylococcus aureus transmission and infections. We aimed to determine whether transmitted S. aureus isolates were associated with increased risk of multidrug resistance and associated traits.

METHODS

S. aureus isolates obtained from intraoperative environmental, patient skin, and provider hand reservoirs among 274 operating room case pairs (1st and 2nd case of the day) across 3 major academic medical centers from March 2009 to February 2010 underwent systematic-phenotypic-genomic analysis to identify clonal transmission events. The association of clonal S. aureus transmission with multidrug resistance and resistance traits was investigated. Transmission dynamics were characterized.

RESULTS

Transmitted isolates (N=58) were associated with increased risk of multi-drug antibiotic resistance [33% (19/58) transmitted vs. 10% (12/115) other isolates, risk ratio 3.14, 99% CI 1.34-7.38, P=0.0006]. Transmission was associated with a significant increase in resistance traits including mecA [40% transmitted isolates vs. 17% other isolates, risk ratio 2.28, P=0.0026] and ant (6)-Ia [26% transmitted isolates vs. 9% other isolates, risk ratio 2.97, P=0.0050]. Provider hands were a frequent reservoir of origin, between-case a common mode of transmission, and patient skin and provider hands frequent transmission locations for multidrug resistant pathogens.

CONCLUSIONS

Intraoperative S. aureus transmission was associated with multidrug resistance and resistance traits. Proven infection control measures should be leveraged to target intraoperative transmission of multidrug resistant pathogens.

Metronomic chemotherapy as a potential partner of immune checkpoint inhibitors for metastatic colorectal cancer treatment

The use of immune checkpoint inhibitors (ICIs) in clinical practice for the treatment of metastatic colorectal cancer (mCRC) is currently limited to patients with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H), which comprise less than 5% of all mCRC cases. Combining ICIs with anti-angiogenic inhibitors, which modulate the tumor microenvironment, may reinforce and synergize the anti-tumor immune responses of ICIs. In mCRCs, combinations of pembrolizumab and lenvatinib have shown good efficacy in early phase trials. These results suggest the potential utility of immune modulators as partners in combination treatment with ICIs in immunologically cold microsatellite stable, as well as hot dMMR/MSI-H tumors. Unlike conventional pulsatile maximum tolerated dose chemotherapy, low-dose metronomic (LDM) chemotherapy recruits immune cells and normalizes vascular-immune crosstalk, similar to anti-angiogenic drugs. LDM chemotherapy mostly modulates the tumor stroma rather than directly killing tumor cells. Here, we review the mechanism of LDM chemotherapy in terms of immune modulation and its potential as a combination partner with ICIs for the treatment of patients with mCRC tumors, most of which are immunologically cold.

Bacterial metabolism and susceptibility to cell wall-active antibiotics

Bacterial infections are increasingly resistant to antimicrobial therapy. Intense research focus has thus been placed on identifying the mechanisms that bacteria use to resist killing or growth inhibition by antibiotics and the ways in which bacteria share these traits with one another. This work has led to the advancement of new drugs, combination therapy regimens, and a deeper appreciation for the adaptability seen in microorganisms. However, while the primary mechanisms of action of most antibiotics are well understood, the more subtle contributions of bacterial metabolic state to repairing or preventing damage caused by antimicrobials (thereby promoting survival) are still understudied. Here, we review a modern viewpoint on a classical system: examining bacterial metabolism's connection to antibiotic susceptibility. We dive into the relationship between metabolism and antibiotic efficacy through the lens of growth rate, energy state, resource allocation, and the infection environment, focusing on cell wall-active antibiotics.

The Role of Hyperbaric Oxygen Therapy in the Treatment of Surgical Site Infections: A Narrative Review

Surgical site infections (SSIs) are among the most prevalent postoperative complications, with significant morbidity and mortality worldwide. In the past half century, hyperbaric oxygen therapy (HBOT), the administration of 100% oxygen intermittently under a certain pressure, has been used as either a primary or alternative therapy for the management or treatment of chronic wounds and infections. This narrative review aims to gather information and evidence supporting the role of HBOT in the treatment of SSIs. We followed the Scale for the Quality Assessment of Narrative Review Articles (SANRA) guidelines and scrutinized the most relevant studies identified in Medline (via PubMed), Scopus, and Web of Science. Our review indicated that HBOT can result in rapid healing and epithelialization of various wounds and has potential beneficial effects in the treatment of SSIs or other similar infections following cardiac, neuromuscular scoliosis, coronary artery bypass, and urogenital surgeries. Moreover, it was a safe therapeutic procedure in most cases. The mechanisms related to the antimicrobial activity of HBOT include direct bactericidal effects through the formation of reactive oxygen species (ROS), the immunomodulatory effect of HBOT that increase the antimicrobial effects of the immune system, and the synergistic effects of HBOT with antibiotics. We emphasized the essential need for further studies, especially randomized clinical trials and longitudinal studies, to better standardize HBOT procedures as well as to determine its full benefits and possible side effects.

Identification of Microbial Species and Analysis of Antimicrobial Resistance Patterns in Acute Cholangitis Patients with Malignant and Benign Biliary Obstructions: A Comparative Study

Background and Objectives: Acute cholangitis (AC) is still lethal if not treated promptly and effectively. Biliary drainage, also known as source control, has been acknowledged as the backbone treatment for patients with AC; nonetheless, antimicrobial therapy allows these patients to undergo non-emergent drainage procedures. This retrospective study aims to observe the bacterial species involved in AC and analyze the antimicrobial resistance patterns. Materials and Methods: Data were collected for four years, comparing patients with benign and malignant bile duct obstruction as an etiology for AC. A total of 262 patients were included in the study, with 124 cases of malignant obstruction and 138 cases of benign obstruction. Results: Positive bile culture was obtained in 192 (73.3%) patients with AC, with a higher rate among the benign group compared with malignant etiologies (55.7%.vs 44.3%). There was no significant difference between the Tokyo severity scores in the two study groups, identifying 34.7% cases of malignant obstruction with Tokyo Grade 1 (TG1) and 43.5% cases of TG1 among patients with benign obstruction. Similarly, there were no significant differences between the number of bacteria types identified in bile, most of them being monobacterial infections (19% in the TG1 group, 17% in the TG2 group, and 10% in the TG3 group). The most commonly identified microorganism in blood and bile cultures among both study groups was E. coli (46.7%), followed by Klebsiella spp. (36.0%) and Pseudomonas spp. (8.0%). Regarding antimicrobial resistance, it was observed that significantly more patients with malignant bile duct obstruction had a higher percentage of bacterial resistance for cefepime (33.3% vs. 11.7%, p-value = 0.0003), ceftazidime (36.5% vs. 14.5%, p-value = 0.0006), meropenem (15.4% vs. 3.6%, p-value = 0.0047), and imipenem (20.2% vs. 2.6%, p-value < 0.0001). Conclusions: The positive rate of biliary cultures is higher among patients with benign biliary obstruction, while the malignant etiology correlates with increased resistance to cefepime, ceftazidime, meropenem, and imipenem.

Rationale for Colonic Pre-Habilitation Prior to Restoration of Gastrointestinal Continuity

The emergence of the gut microbiome as a complex ecosystem that plays a key role in human heath and disease has touched virtually every aspect of medical and surgical care. With the advent of next-generation technology to interrogate the microbiome at the level of its membership, community structure and production of metabolites, applying measures by which the gut microbiome can be manipulated to the advantage of both the patient and provider is now possible. Among the many proposed methods, the most practical and promising is dietary pre-habilitation of the gut microbiome prior to high-risk anastomotic surgery. In this review, we will outline the scientific rationale and molecular underpinning that support dietary pre-habilitation as a practical and deliverable method to prevent complications after high-risk anastomotic surgery.

Macrolide antibiotics activate the integrated stress response and promote tumor proliferation

Macrolide antibiotics are widely used antibacterial agents that are associated with autophagy inhibition. This study aimed to investigate the association between macrolide antibiotics and malignant tumors, as well as the effect on autophagy, reactive oxygen species (ROS) accumulation and integrated stress response (ISR). The meta-analysis indicated a modestly higher risk of cancer in macrolide antibiotic ever-users compared to non-users. Further experiments showed that macrolides block autophagic flux by inhibiting lysosomal acidification. Additionally, azithromycin, a representative macrolide antibiotic, induced the accumulation of ROS, and stimulated the ISR and the activation of transcription factor EB (TFEB) and TFE3 in a ROS-dependent manner. Finally, animal experiments confirmed that azithromycin promoted tumor progression in vivo, which could be receded by N-acetylcysteine, an inhibitor of ROS and ISR. Overall, this study reveals the potential role of macrolide antibiotics in malignant progression and highlights the need for further investigation into their effects.

Cost Effectiveness of Rectal Culture-based Antibiotic Prophylaxis in Transrectal Prostate Biopsy: The Results from a Randomized, Nonblinded, Multicenter Trial

Background

Culture-based antibiotic prophylaxis is a plausible strategy to reduce infections after transrectal prostate biopsy (PB) related to fluoroquinolone-resistant pathogens.

Objective

To assess the cost effectiveness of rectal culture-based prophylaxis compared with empirical ciprofloxacin prophylaxis.

Design setting and participants

The study was performed alongside a trial in 11 Dutch hospitals investigating the effectiveness of culture-based prophylaxis in transrectal PB between April 2018 and July 2021 (trial registration number: NCT03228108).

Intervention

Patients were 1:1 randomized for empirical ciprofloxacin prophylaxis (oral) or culture-based prophylaxis. Costs for both prophylactic strategies were determined for two scenarios: (1) all infectious complications within 7 d after biopsy and (2) culture-proven Gram-negative infections within 30 d after biopsy.

Outcome measurements and statistical analysis

Differences in costs and effects (quality-adjusted life-years [QALYs]) were analyzed from a healthcare and societal perspective (including productivity losses, and travel and parking costs) using a bootstrap procedure presenting uncertainty surrounding the incremental cost-effectiveness ratio in a cost-effectiveness plane and acceptability curve.

Results and limitations

For the 7-d follow-up period, culture-based prophylaxis (n = 636) was €51.57 (95% confidence interval [CI] 6.52-96.63) more expensive from a healthcare perspective and €16.95 (95% CI -54.29 to 88.18) from a societal perspective than empirical ciprofloxacin prophylaxis (n = 652). Ciprofloxacin-resistant bacteria were detected in 15.4%. Extrapolating our data, from a healthcare perspective, 40% ciprofloxacin resistance would lead to equal cost for both strategies. Results were similar for the 30-d follow-up period. No significant differences in QALYs were observed.

Conclusions

Our results should be interpreted in the context of local ciprofloxacin resistance rates. In our setting, from a healthcare perspective, culture-based prophylaxis was significantly more expensive than empirical ciprofloxacin prophylaxis. From a societal perspective, culture-based prophylaxis was somewhat more cost effective against the threshold value customary for the Netherlands (€80.000).

Patient summary

Culture-based prophylaxis in transrectal prostate biopsy was not associated with reduced costs compared with empirical ciprofloxacin prophylaxis.

Bacterial antibiotic resistance among cancer inpatients in China: 2016-20

BACKGROUND

The incidence of infections among cancer patients is as high as 23.2-33.2% in China. However, the lack of information and data on the number of antibiotics used by cancer patients is an obstacle to implementing antibiotic management plans.

AIM

This study aimed to investigate bacterial infections and antibiotic resistance in Chinese cancer patients to provide a reference for the rational use of antibiotics.

DESIGN

This was a 5-year retrospective study on the antibiotic resistance of cancer patients.

METHODS

In this 5-year surveillance study, we collected bacterial and antibiotic resistance data from 20 provincial cancer diagnosis and treatment centers and three specialized cancer hospitals in China. We analyzed the resistance of common bacteria to antibiotics, compared to common clinical drug-resistant bacteria, evaluated the evolution of critical drug-resistant bacteria and conducted data analysis.

FINDINGS

Between 2016 and 2020, 216 219 bacterial strains were clinically isolated. The resistance trend of Escherichia coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, cefotaxime, piperacillin/tazobactam and imipenem was relatively stable and did not significantly increase over time. The resistance of Pseudomonas aeruginosa strains to all antibiotics tested, including imipenem and meropenem, decreased over time. In contrast, the resistance of Acinetobacter baumannii strains to carbapenems increased from 4.7% to 14.7%. Methicillin-resistant Staphylococcus aureus (MRSA) significantly decreased from 65.2% in 2016 to 48.9% in 2020.

CONCLUSIONS

The bacterial prevalence and antibiotic resistance rates of E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, S. aureus and MRSA were significantly lower than the national average.

Determinants of antimicrobial resistance occurrence in animal‐based food, perceived by livestock farmers: A qualitative phenomenological study

Background and Purpose of the Study

The determinants of antimicrobial resistance in human medicine have been copiously explored. On the other hand, the existing research in veterinary medicine and animal husbandry is in its infancy. The present qualitative study used the one‐health approach to explore farmers’ attitudes toward antimicrobial use and antimicrobial stewardship.

Methodology

The present qualitative study was phenomenological in type. It was conducted in 2022 in the two cities of Kerman and Bandar Abbas in Iran. The data were collected through in‐depth interviews by semistructured interviews with 17 livestock, poultry, and aquatic animal breeders selected through purposive sampling. The interviews lasted between 35 and 65 min in the Farsi language. The data were analyzed using conventional qualitative content analysis and Colaizzi's seven‐step analysis technique.

Results

The open coding was done in MAXQDA 10 and the results of data analysis were classified into five main themes and 17 subthemes subcategories. The main categories include personal determinants, contextual determinants, legal and regulatory determinants, social determinants, and economic determinants.

Conclusion

Considering the increasing use of antibiotics among livestock farmers and breeders of animals used as human food, different measures such as educational, regulatory, social, and even cultural interventions may be able to control and prevent antimicrobial resistance.

NIR-II xanthene dyes with structure-inherent bacterial targeting for efficient photothermal and broad-spectrum antibacterial therapy

Development of novel broad-spectrum sterilization is an efficient strategy that can overcome drug resistance and avoid antibiotics abuse toward bacterial-infected diseases. Photothermal therapy (PTT) in the second near-infrared (NIR-II) therapeutic window with an increased tissue penetration and elevated maximal permissible exposure has attracted considerable attention in antibacterial applications. However, the lack of bacterial-targeted photothermal agents limits their further development. Herein, we developed three xanthene derivatives (CNs) with intense light harvesting ability around 1180 nm. Their bulky planar conformations facilitated the formation of H-aggregates with outstanding photothermal conversion ability and good photostability in the NIR-II therapeutic bio window. By manipulating side chains of CNs, their liposomes exhibited different surface charges, ranging from negative to positive. Remarkably, the intermolecular hydrogen bonding of CN3 dimer drived the positively charged xanthene skeleton exposed to the periphery, which endowed it natural bacterial targeting potency. Therefore, CN3 possessed a good NIR-II photothermal and broad-spectrum sterilization against Gram-positive and Gram-negative bacteria. The photothermal antibacterial activities for S. aureus and E. coli were 99.4% and 99.2%, respectively, promoting significant wound healing in bacteria-infected mice with superior biocompatibility. This structure-inherent bacterial targeting strategy as a proof-of-concept shows an efficient broad-spectrum bacterial inactivation, indicating more encouraging NIR-II photothermal antibacterial therapy. STATEMENT OF SIGNIFICANCE: Photothermal therapy (PTT) in the second near-infrared region (NIR-II, 1000-1700 nm) enables the treatment of deep inflammation more satisfactory due to higher tissue penetration depth. In this work, three new NIR-II xanthene derivatives (CNs) with intense light harvesting ability around 1180 nm were developed. CNs showed typical H-aggregated performance with bulky planar conformations and outstanding photothermal conversion ability. Density functional theory calculations revealed that the intermolecular hydrogen bonding of CN3 dimer drived the exposure of positively charged xanthene skeleton to periphery of dimer. Therefore, CN3 NPs possessed natural bacterial targeting potency and excellent NIR-II photothermal and broad-spectrum sterilization, and so as to significantly promote the wound healing of Gram-positive / negative bacteria infected mice.

Bacterial virulence regulation through soluble peptidoglycan fragments sensing and response: knowledge gaps and therapeutic potential

Given the growing clinical-epidemiological threat posed by the phenomenon of antibiotic resistance, new therapeutic options are urgently needed, especially against top nosocomial pathogens such as those within the ESKAPE group. In this scenario, research is pushed to explore therapeutic alternatives and, among these, those oriented toward reducing bacterial pathogenic power could pose encouraging options. However, the first step in developing these antivirulence weapons is to find weak points in the bacterial biology to be attacked with the goal of dampening pathogenesis. In this regard, during the last decades some studies have directly/indirectly suggested that certain soluble peptidoglycan-derived fragments display virulence-regulatory capacities, likely through similar mechanisms to those followed to regulate the production of several β-lactamases: binding to specific transcriptional regulators and/or sensing/activation of two-component systems. These data suggest the existence of intra- and also intercellular peptidoglycan-derived signaling capable of impacting bacterial behavior, and hence likely exploitable from the therapeutic perspective. Using the well-known phenomenon of peptidoglycan metabolism-linked β-lactamase regulation as a starting point, we gather and integrate the studies connecting soluble peptidoglycan sensing with fitness/virulence regulation in Gram-negatives, dissecting the gaps in current knowledge that need filling to enable potential therapeutic strategy development, a topic which is also finally discussed.

Mass drug administration of azithromycin: an analysis

BACKGROUND

WHO recommends mass drug administration (MDA) of the antibiotic azithromycin for children aged 1-11 months in areas with high rates of infant and child mortality. Notwithstanding the substantial potential benefits of lowering childhood mortality, MDA raises understandable concerns about exacerbating antibiotic resistance.

OBJECTIVES

In this study, we aimed to evaluate the use of MDA using both quantitative and ethical considerations.

SOURCES

We performed a series of literature searches between July 2019 and June 2022.

CONTENT

We first compared MDA with other uses of antibiotics using the standard metric of 'number needed to treat', and five additional criteria: (1) other widely accepted uses of anti-infectives (2) absolute use (i.e. total number), of antibiotics, (3) risk-benefit trade-off, (4) availability of short-term alternatives, and (5) the precedent for implementing similar interventions. We found that MDA falls well within a justifiable range when compared with widely accepted uses of antibiotics in terms of the number needed to treat. The other five criteria we considered provided further support for the use of MDA to prevent childhood mortality.

IMPLICATIONS

Although better data on antibiotic use and resistance are needed, efforts to reduce antibiotic use and resistance should not start with halting MDA of azithromycin in the areas with the highest rates of childhood mortality. Improving data to inform this decision is critical. However, on the basis of the best evidence available, we believe that concerns regarding resistance should not thwart MDA; instead, MDA should be accompanied by robust plans to monitor its efficacy and changes in resistance levels. Similar considerations could be included in a framework for evaluating the benefits of antibiotics against the risk of resistance in other contexts.

Developing a Modeling Framework for Quantifying the Health and Cost Implications of Antibiotic Resistance for Surgical Procedures

Background. Antimicrobial resistance (AMR) is a global public health threat. The wider implications of AMR, such as the impact of antibiotic resistance (ABR) on surgical procedures, are yet to be quantified. The objective of this study was to produce a conceptual modeling framework to provide a basis for estimating the current and potential future consequences of ABR for surgical procedures in England. Design. A framework was developed using literature-based evidence and structured expert elicitation. This was applied to populations undergoing emergency repair of the neck of the femur and elective colorectal resection surgery. Results. The framework captures the implications of increasing ABR by allowing for higher rates of surgical site infection (SSI) as the effectiveness of antibiotic prophylaxis wanes and worsened outcomes following SSIs to reflect reduced antibiotic treatment effectiveness. The expert elicitation highlights the uncertainty in quantifying the impact of ABR, reflected in the results. A hypothetical SSI rate increase of 14% in a person undergoing emergency repair of the femur could increase costs by 39% (-2% to 108% credible interval [CI]) and decrease quality-adjusted life-years by 11% (0.4% to 62% CI) over 15 y. Conclusions. The modeling framework is a starting point for addressing the implication of ABR on the outcomes and costs of surgeries. Due to clinical uncertainty highlighted in the expert elicitation process, the numerical outputs of the case studies should not be focused on but rather the framework itself, illustration of the evidence gaps, the benefit of expert elicitation in quantifying parameters with limited data, and the potential magnitude of the impact of ABR on surgical procedures. Implications. The framework can be used to support research surrounding the health and cost burden of ABR in England.

Highlights

The modeling framework is a starting point for assessing the health and cost impacts of antibiotic resistance on surgeries in England.Formulating a framework and synthesizing evidence to parameterize data gaps provides targets for future research.Once data gaps are addressed, this modeling framework can be used to feed into overall estimates of the health and cost burden of antibiotic resistance and evaluate control policies.

Inhibition of Enzymatic Acetylation-Mediated Resistance to Plazomicin by Silver Ions

Plazomicin is a recent U.S. Food and Drug Administration (FDA)-approved semisynthetic aminoglycoside. Its structure consists of a sisomicin scaffold modified by adding a 2(S)-hydroxy aminobutyryl group at the N1 position and a hydroxyethyl substituent at the 6' position. These substitutions produced a molecule refractory to most aminoglycoside-modifying enzymes. The main enzyme within this group that recognizes plazomicin as substrate is the aminoglycoside 2'-N-acetyltransferase type Ia [AAC(2')-Ia], which reduces the antibiotic's potency. Designing formulations that combine an antimicrobial with an inhibitor of resistance is a recognized strategy to extend the useful life of existing antibiotics. We have recently found that several metal ions inhibit the enzymatic inactivation of numerous aminoglycosides mediated by the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib]. In particular, Ag+, which also enhances the effect of aminoglycosides by other mechanisms, is very effective in interfering with AAC(6')-Ib-mediated resistance to amikacin. Here we report that silver acetate is a potent inhibitor of AAC(2')-Ia-mediated acetylation of plazomicin in vitro, and it reduces resistance levels of Escherichia coli carrying aac(2')-Ia. The resistance reversion assays produced equivalent results when the structural gene was expressed under the control of the natural or the blaTEM-1 promoters. The antibiotic effect of plazomicin in combination with silver was bactericidal, and the mix did not show significant toxicity to human embryonic kidney 293 (HEK293) cells.

Chemical Synthesis of Innovative Silver Nanohybrids with Synergistically Improved Antimicrobial Properties

Background

The wide use of antibiotics has created challenges related to antibiotic-resistant bacteria, which have been increasingly found in recent decades. Antibiotic resistance has led to limited choices of antibiotics. Multiple old antimicrobial agents have high antimicrobial properties toward bacteria, but they unfortunately also possess high toxicity toward humans. For instance, silver (Ag) compounds were frequently used to treat tetanus and rheumatism in the 19th century and to treat colds and gonorrhea in the early 20th century. However, the high toxicity of Ag has limited its clinical use.

Purpose

We aimed to reformulate Ag to reduce its toxicity toward human cells like osteoblasts and to optimize its antimicrobial properties.

Results

Ag, an old antimicrobial agent, was reformulated by hybriding nanomaterials of different dimensions, and silver nanoparticles (AgNPs) of controllable sizes (95-200 nm) and varying shapes (cube, snowflake, and sphere) were synthesized on carbon nanotubes (CNTs). The obtained AgNP-CNT nanohybrids presented significantly higher killing efficacy against Staphylococcus aureus (S. aureus) compared to AgNPs at the same molar concentration and showed synergism in killing S. aureus at 0.2 and 0.4 mM. AgNPs presented significant osteoblast toxicity; in contrast, AgNP-CNT nanohybrids demonstrated significantly enhanced osteoblast viability at 0.04-0.8 mM. The killing of S. aureus by AgNP-CNT nanohybrids was fast, occurring within 15 min.

Conclusion

Ag was successfully reformulated and Ag nanohybrids with various AgNP shapes on CNTs were synthesized. The nanohybrids presented significantly enhanced antimicrobial properties and significantly higher osteoblast cell viability compared to AgNPs, showing promise as an innovative antimicrobial nanomaterial for a broad range of biomedical applications.

Gut microbiota: a potential target for improved cancer therapy

Drug resistance and toxicity are major challenges observed during cancer treatment. In recent years, gut microbiota has been found to be strongly associated with the efficacy, toxicity, and side effects of chemotherapy, radiotherapy, and immunotherapy. Both preclinical studies and clinical trials have demonstrated the potential of microbiota modulation for cancer treatment. The human gut microbiota has exciting prospects for developing biomarkers to predict the outcome of cancer treatment. Moreover, multiple approaches can alter the gut microbiota composition, including faecal microbiota transplantation (FMT), probiotics, antibiotics (ATB), and diet. We describe the mechanisms by which the gut microbiota influences the efficacy and toxicity of cancer therapy, disease-related biomarkers, and methods to target the gut microbiota to improve outcomes. The purpose of this review is to provide new ideas for optimising cancer therapy by providing up-to-date information on the relationship between gut microbiota and cancer therapy, and hopes to find new targets for cancer treatment from human microbiota.

ESCMID/EUCIC clinical practice guidelines on perioperative antibiotic prophylaxis in patients colonized by multidrug-resistant Gram-negative bacteria before surgery

SCOPE

The aim of the guidelines is to provide recommendations on perioperative antibiotic prophylaxis (PAP) in adult inpatients who are carriers of multidrug-resistant Gram-negative bacteria (MDR-GNB) before surgery.

METHODS

These evidence-based guidelines were developed after a systematic review of published studies on PAP targeting the following MDR-GNB: extended-spectrum cephalosporin-resistant Enterobacterales, carbapenem-resistant Enterobacterales (CRE), aminoglycoside-resistant Enterobacterales, fluoroquinolone-resistant Enterobacterales, cotrimoxazole-resistant Stenotrophomonas maltophilia, carbapenem-resistant Acinetobacter baumannii (CRAB), extremely drug-resistant Pseudomonas aeruginosa, colistin-resistant Gram-negative bacteria, and pan-drug-resistant Gram-negative bacteria. The critical outcomes were the occurrence of surgical site infections (SSIs) caused by any bacteria and/or by the colonizing MDR-GNB, and SSI-attributable mortality. Important outcomes included the occurrence of any type of postsurgical infectious complication, all-cause mortality, and adverse events of PAP, including development of resistance to targeted (culture-based) PAP after surgery and incidence of Clostridioides difficile infections. The last search of all databases was performed until April 30, 2022. The level of evidence and strength of each recommendation were defined according to the Grading of Recommendations Assessment, Development and Evaluation approach. Consensus of a multidisciplinary expert panel was reached for the final list of recommendations. Antimicrobial stewardship considerations were included in the recommendation development.

RECOMMENDATIONS

The guideline panel reviewed the evidence, per bacteria, of the risk of SSIs in patients colonized with MDR-GNB before surgery and critically appraised the existing studies. Significant knowledge gaps were identified, and most questions were addressed by observational studies. Moderate to high risk of bias was identified in the retrieved studies, and the majority of the recommendations were supported by low level of evidence. The panel conditionally recommends rectal screening and targeted PAP for fluoroquinolone-resistant Enterobacterales before transrectal ultrasound-guided prostate biopsy and for extended-spectrum cephalosporin-resistant Enterobacterales in patients undergoing colorectal surgery and solid organ transplantation. Screening for CRE and CRAB is suggested before transplant surgery after assessment of the local epidemiology. Careful consideration of the laboratory workload and involvement of antimicrobial stewardship teams before implementing the screening procedures or performing changes in PAP are warranted. High-quality prospective studies to assess the impact of PAP among CRE and CRAB carriers performing high-risk surgeries are advocated. Future well-designed clinical trials should assess the effectiveness of targeted PAP, including the monitoring of MDR-GNB colonization through postoperative cultures using European Committee on Antimicrobial Susceptibility Testing clinical breakpoints.

Optimization of 1,2,4-Triazole-3-thiones toward Broad-Spectrum Metallo-β-lactamase Inhibitors Showing Potent Synergistic Activity on VIM- and NDM-1-Producing Clinical Isolates

Metallo-β-lactamases (MBLs) contribute to the resistance of Gram-negative bacteria to carbapenems, last-resort antibiotics at hospital, and MBL inhibitors are urgently needed to preserve these important antibacterial drugs. Here, we describe a series of 1,2,4-triazole-3-thione-based inhibitors displaying an α-amino acid substituent, which amine was mono- or disubstituted by (hetero)aryl groups. Compounds disubstituted by certain nitrogen-containing heterocycles showed submicromolar activities against VIM-type enzymes and strong NDM-1 inhibition (K_i = 10-30 nM). Equilibrium dialysis, native mass spectrometry, isothermal calorimetry (ITC), and X-ray crystallography showed that the compounds inhibited both VIM-2 and NDM-1 at least partially by stripping the catalytic zinc ions. These inhibitors also displayed a very potent synergistic activity with meropenem (16- to 1000-fold minimum inhibitory concentration (MIC) reduction) against VIM-type- and NDM-1-producing ultraresistant clinical isolates, including Enterobacterales and Pseudomonas aeruginosa. Furthermore, selected compounds exhibited no or moderate toxicity toward HeLa cells, favorable absorption, distribution, metabolism, excretion (ADME) properties, and no or modest inhibition of several mammalian metalloenzymes.

Awareness regarding antimicrobial resistance and confidence to prescribe antibiotics in dentistry: a cross-continental student survey

BACKGROUND

The antimicrobial resistance (AMR) crisis is a major global threat and one of its biggest drivers is the overuse of antibiotics in humans. Dentists are responsible for 5-10% antibiotic prescriptions worldwide and recent data suggest that knowledge and prescribing practices need improvement.

METHODS

A cross-sectional web-survey was sent to dental students from six universities in Norway, Canada, and Brazil. Topics addressed covered awareness, confidence to prescribe antibiotics, and education needs. Data were presented descriptively and statistical testing was employed to compare group means when applicable.

RESULTS

In total, 562 responses were collected across the three countries with a response rate of 28.6%. 'Antibiotic resistance' was among the highest priorities (scale 1-10) with an average of 8.86 (SEM ± 0.05), together with 'Gender inequality' (8.68 ± 0.07) and 'Climate change' (8.68 ± 0.07). Only 28.8% thought that Dentistry was engaged in national/international campaigns promoting awareness on the topic and 8.9% stated to have heard about the 'One Health' concept. Final year dental students showed an average confidence to prescribe antibiotics of 7.59 (± 0.14). Most students demonstrated interest in receiving additional education on all topics listed, with the three most pressing being 'antibiotic prescription for treatment of infections' (82.9%), 'drug interactions' (80.9%), and 'spread of antibiotic resistance' (79.6%). A trend was observed between higher awareness regarding the topic and higher confidence to prescribe.

CONCLUSIONS

There is a need to revisit dental education on antibiotic resistance with a global perspective and to create more stewardship initiatives that promote awareness on the topic.

Rectal culture-based versus empirical antibiotic prophylaxis to prevent infectious complications in men undergoing transrectal prostate biopsy: a randomized, non-blinded multicenter trial

BACKGROUND

An increase of infections after transrectal prostate biopsy (PB), related to an increasing number of patients with ciprofloxacin-resistant rectal flora, necessitates the exploration of alternatives for the traditionally standard used empirical prophylaxis with ciprofloxacin. We compared infectious complication rates after transrectal PB using empirical ciprofloxacin prophylaxis versus culture-based prophylaxis.

METHODS

In this non-blinded, randomized trial, between April 4, 2018 to July 30, 2021, we enrolled 1538 patients from 11 Dutch hospitals undergoing transrectal PB. After rectal swab collection, patients were 1:1 randomized to receive empirical prophylaxis with oral ciprofloxacin (control group; CG), or culture-based prophylaxis (intervention group; IG). Primary outcome was any infectious complication within seven days post-biopsy. Secondary outcomes were infectious complications within 30 days, and bacteremia and bacteriuria within seven and 30 days post-biopsy. For primary outcome analysis, the Chi-square test stratified for hospital was used. Trial registration number: NCT03228108.

RESULTS

Data from 1288 patients (83.7%) were available for analysis (CG: 652 and IG: 636). Infection rates within seven days post-biopsy were 4.3% (n = 28) (CG) and 2.5% (n = 16) (IG) (p-value: 0.08; reduction: -1.8%; 95% CI -0.004 to 0.040). Ciprofloxacin-resistant bacteria were detected in 15.2% (n = 1288). In the CG, the presence of ciprofloxacin-resistant rectal flora resulted in a 6.2 fold higher risk of early post-biopsy infection.

CONCLUSIONS

Our study supports the use of culture-based prophylaxis to reduce infectious complications after transrectal PB. Despite adequate prophylaxis, post-biopsy infections can still occur. Therefore, culture-based prophylaxis must be weighed against other strategies that could reduce post-biopsy infections.

Antibacterial and Antioxidant Properties of Extracts of Yucca Baccata, a Plant of Northwestern Mexico, against Pathogenic Bacteria

Introduction

Bacterial agents and oxidative reactions are involved in health and food preservation issues, and Yucca baccata (Y. baccata) can be a source of compounds with practical applications in both areas, but its investigation remains limited.

Materials and Methods

Butanolic (YBE) and aqueous (YAE) extracts were obtained from the stem of Y. baccata. The total saponin, phenolic, and flavonoid contents were analyzed in the YBE and YAE. The antioxidant capacity of the extracts was determined by the DPPH, TEAC, FRAP, and ORAC assays. Seven Gram-positive and five Gram-negative pathogenic bacteria strains were used to determine the MIC and MBC.

Results

Saponin contents were 30% and 1.81% (w/w) in the YBE and YAE, respectively. The total phenolic and flavonoid contents in the extracts were 29.5 μg GAEmg⁻¹ (2.95%) and 5.58 μg GAEmg⁻¹ (0.56%) in the YBE and 69.92 μg QEmg⁻¹ (7.0%) and 1.65 μg QEmg⁻¹ (0.165%) in the YAE. The antioxidant capacity values of YBE were 29.18 μg TEmg⁻¹, 121.8 μg TEmg⁻¹, 33.41 μg TEmg⁻¹, and 156.84 μg TEmg⁻¹ by the DPPH, TEAC, FRAP, and ORAC assays, respectively. YAE had lower antioxidant values than YBE (P < 0.05). Values of 80 mgmL⁻¹ and 100 mgmL⁻¹ were estimated for MIC and MBC of YBE against the Gram-positive bacteria. Values of 100 mgmL⁻¹ and 120 mgmL⁻¹ for MIC and MBC of YBE were estimated against the Gram-negative bacteria. No MIC and MBC were obtained for YAE.

Conclusion

YBE exhibited higher antioxidant activity than YAE. Apparently, antibacterial properties of the YBE tended to be higher than those of the YAE.

A potent antibiotic-loaded bone-cement implant against staphylococcal bone infections

New antibiotics should ideally exhibit activity against drug-resistant bacteria, delay the development of bacterial resistance to them and be suitable for local delivery at desired sites of infection. Here, we report the rational design, via molecular-docking simulations, of a library of 17 candidate antibiotics against bone infection by wild-type and mutated bacterial targets. We screened this library for activity against multidrug-resistant clinical isolates and identified an antibiotic that exhibits potent activity against resistant strains and the formation of biofilms, decreases the chances of bacterial resistance and is compatible with local delivery via a bone-cement matrix. The antibiotic-loaded bone cement exhibited greater efficacy than currently used antibiotic-loaded bone cements against staphylococcal bone infections in rats. Potent and locally delivered antibiotic-eluting polymers may help address antimicrobial resistance.

Disease burden, associated mortality and economic impact of antimicrobial resistant infections in Australia

BACKGROUND

The growing spread of antimicrobial resistance (AMR) is accepted as a threat to humans, animals and the environment. This threat is considered to be both country specific and global, with bacteria resistant to antibiotic treatment geographically dispersed. Despite this, we have very few Australian estimates available that use national surveillance data supplemented with measures of risk, to generate reliable and actionable measures of AMR impact. These data are essential to direct policies and programs and support equitable healthcare resource utilisation. Importantly, such data can lead to implementation of programs to improved morbidity and mortality of patients with a resistant infection.

METHODS

Using data from a previous case-cohort study, we estimated the AMR-associated health and economic impact caused by five hospital-associated AMR pathogens (Enterococcus spp., E. coli, K. pneumoniae, P. aeruginosa and S. aureus) in patients with a bloodstream, urinary tract, or respiratory tract infection in Australia in 2020. We estimated disease burden based on the counterfactual scenario in which all AMR infections were replaced by no infection.We used a population-level simulation model to compute AMR-associated mortality, loss of quality-adjusted life years and costs.

FINDINGS

In 2020, there were 1,031 AMR-associated deaths (95% uncertainty interval [UI] 294, 2,615) from the five resistant hospital-associated infections in Australia. The greatest odds of dying were from respiratory infections (ceftazidime-resistant P. aeruginosa) and bloodstream infections, both resulting in high hospital and premature death costs. MRSA bacteraemia contributed the most to hospital costs (measured as bed-days) as patients with this infection resulted in additional 12,818 (95% UI 7246, 19966) hospital bed-days and cost the hospitals an extra $24,366,741 (95%UI $13,774,548, $37,954,686) per year. However, the cost of premature death from five resistant pathogens was $438,543,052, which was by far greater than the total hospital cost ($71,988,858). We estimate a loss of 27,705 quality-adjusted life years due to the five AMR pathogens.

INTERPRETATION

These are the first Australian estimates of AMR-associated health and economic impact. Country-level estimates of AMR impact are needed to provide local evidence to better inform programs and health policies to reduce morbidity and mortality associated with infection. The burden in hospital is likely an underestimate of the impact of AMR due to community-associated infections where data are limited, and the AMR burden is high. This should now be the focus of future study in this area.

FUNDING

TMW was supported by the Australian Partnership for Preparedness Research on Infectious Disease Emergencies (APPRISE) (grant number GNT1116530) Fellowship.

The design of cell-selective tryptophan and arginine-rich antimicrobial peptides by introducing hydrophilic uncharged residues

Antimicrobial peptides (AMPs) are considered to be powerful weapons in the fight against traditional antibiotic resistance due to their unique membrane-disruptive mechanism. The combination of traditional and classical hydrophobic tryptophan (W) residues and hydrophilic charged arginine (R) residues is considered as the first choice for the minimalist design of AMPs due to its potent performance in antibacterial activity. However, some W- and R-rich AMPs that are not rationally designed and contain excessive repeats of W and R residues may cause severe cytotoxicity and hemolysis. To address this issue, we designed the (WRX)_n (where X = hydrophilic uncharged amino residues; n = number of repeat units) series engineered peptides with high cell selectivity by introducing hydrophilic uncharged threonine (T), serine (S), glutamine (Q) or asparagine (N) residues into the minimalist design of W- and R-rich AMPs. The results showed that the introduction of these hydrophilic uncharged amino residues, especially T residues, significantly improved the cell selectivity of the W- and R-rich engineered peptides. Among (WRX)_n series engineered peptides, T6 presents a mixture structure of β-turn and α-helix. It has broad spectrum and potent antibacterial activity (no activity against probiotics), good biocompatibility, high selectivity index, strong tolerance (physiological salts, serum acid, alkali, and heat conditions), rapid and efficient time-kill kinetics, and no tendency of resistance. Studies on antibacterial mechanism show that T6 exert antibacterial activity mainly by disrupting bacterial cell membrane and inducing the accumulation of reactive oxygen species in bacterial cells. Furthermore, T6 exhibited potent antibacterial and anti-inflammatory capabilities in vivo in a mouse peritonitis-sepsis model infected with Escherichia coli. In conclusion, our study confirms an effective strategy for the minimalist design of highly cell selective W- and R-rich AMPs by introducing hydrophilic uncharged T residues, which may trigger widespread attention to hydrophilic uncharged amino acid residues, including T residues, and provide new insights into the design of peptide-based antibacterial biomaterials. STATEMENT OF SIGNIFICANCE: We have introduced hydrophilic uncharged T, S, Q or N residues into the minimalist design of W- and R-rich engineered peptides and found that the introduction of these hydrophilic uncharged amino residues, especially the T residues, can significantly improve the cell selectivity of W- and R-rich engineered peptides. The target compound T6 showed potent antibacterial activity, high cell selectivity, strong tolerance, good in vivo efficacy and killed bacteria through multiple mechanisms mainly membrane-disruptive. These findings may spark widespread interest in hydrophilic uncharged amino acid residues, and provide new insights into the design of peptide-based antimicrobial biomaterials.

A Novel Nonantibiotic Gut-directed Strategy to Prevent Surgical Site Infections

OBJECTIVE

To determine the efficacy of an orally delivered phosphate-rich polymer, Pi-PEG, to prevent surgical site infection (SSI) in a mouse model of spontaneous wound infection involving gut-derived pathogens.

BACKGROUND

Evidence suggests that pathogens originating from the gut microbiota can cause postoperative infection via a process by which they silently travel inside an immune cell and contaminate a remote operative site (Trojan Horse Hypothesis). Here, we hypothesize that Pi-PEG can prevent SSIs in a novel model of postoperative SSIs in mice.

METHODS

Mice were fed either a standard chow diet (high fiber/low fat, SD) or a western-type diet (low fiber/high fat, WD), and exposed to antibiotics (oral clindamycin/intraperitoneal cefoxitin). Groups of mice had Pi-PEG added to their drinking water and SSI incidence was determined. Gross clinical infections wound cultures and amplicon sequence variant analysis of the intestinal contents and wound were assessed to determine the incidence and source of the developing SSI.

RESULTS

In this model, consumption of a WD and exposure to antibiotics promoted the growth of SSI pathogens in the gut and their subsequent presence in the wound. Mice subjected to this model drinking water spiked with Pi-PEG were protected against SSIs via mechanisms involving modulation of the gut-wound microbiome.

CONCLUSIONS

A nonantibiotic phosphate-rich polymer, Pi-PEG, added to the drinking water of mice prevents SSIs and may represent a more sustainable approach in lieu of the current trend of greater sterility and the use of more powerful and broader antibiotic coverage.

Quantifying the primary and secondary effects of antimicrobial resistance on surgery patients: Methods and data sources for empirical estimation in England

Antimicrobial resistance (AMR) may negatively impact surgery patients through reducing the efficacy of treatment of surgical site infections, also known as the "primary effects" of AMR. Previous estimates of the burden of AMR have largely ignored the potential "secondary effects," such as changes in surgical care pathways due to AMR, such as different infection prevention procedures or reduced access to surgical procedures altogether, with literature providing limited quantifications of this potential burden. Former conceptual models and approaches for quantifying such impacts are available, though they are often high-level and difficult to utilize in practice. We therefore expand on this earlier work to incorporate heterogeneity in antimicrobial usage, AMR, and causative organisms, providing a detailed decision-tree-Markov-hybrid conceptual model to estimate the burden of AMR on surgery patients. We collate available data sources in England and describe how routinely collected data could be used to parameterise such a model, providing a useful repository of data systems for future health economic evaluations. The wealth of national-level data available for England provides a case study in describing how current surveillance and administrative data capture systems could be used in the estimation of transition probability and cost parameters. However, it is recommended that such data are utilized in combination with expert opinion (for scope and scenario definitions) to robustly estimate both the primary and secondary effects of AMR over time. Though we focus on England, this discussion is useful in other settings with established and/or developing infectious diseases surveillance systems that feed into AMR National Action Plans.