Microbiological profile of patients treated for postoperative peritonitis: temporal trends 1999-2019

BACKGROUND

Temporal changes in the microbiological resistance profile have been reported in several life-threatening infections. However, no data have ever assessed this issue in postoperative peritonitis (POP). Our purpose was to assess the rate of multidrug-resistant organisms (MDROs) in POP over a two-decade period and to analyse their influence on the adequacy of empirical antibiotic therapy (EAT).

METHODS

This retrospective monocentric analysis (1999-2019) addressed the changes over time in microbiologic data, including the emergence of MDROs and the adequacy of EAT for all intensive care unit adult patients treated for POP. The in vitro activities of 10 antibiotics were assessed to determine the most adequate EAT in the largest number of cases among 17 antibiotic regimens in patients with/without MDRO isolates. Our primary endpoint was to determine the frequency of MDRO and their temporal changes. Our second endpoint assessed the impact of MDROs on the adequacy of EAT per patient and their temporal changes based on susceptibility testing. In this analysis, the subgroup of patients with MDRO was compared with the subgroup of patients free of MDRO.

RESULTS

A total of 1,318 microorganisms were cultured from 422 patients, including 188 (45%) patients harbouring MDROs. The growing proportions of MDR Enterobacterales were observed over time (p = 0.016), including ESBL-producing strains (p = 0.0013), mainly related to Klebsiella spp (p < 0.001). Adequacy of EAT was achieved in 305 (73%) patients. Decreased adequacy rates were observed when MDROs were cultured [p = 0.0001 vs. MDRO-free patients]. Over the study period, decreased adequacy rates were reported for patients receiving piperacillin/tazobactam in monotherapy or combined with vancomycin and imipenem/cilastatin combined with vancomycin (p < 0.01 in the three cases). In patients with MDROs, the combination of imipenem/cilastatin + vancomycin + amikacin or ciprofloxacin reached the highest adequacy rates (95% and 91%, respectively) and remained unchanged over time.

CONCLUSIONS

We observed high proportions of MDRO in patients treated for POP associated with increasing proportions of MDR Enterobacterales over time. High adequacy rates were only achieved in antibiotic combinations involving carbapenems and vancomycin, while piperacillin/tazobactam is no longer a drug of choice for EAT in POP in infections involving MDRO.

A novel antimicrobial peptide Scyreptin1-30 from Scylla paramamosain exhibiting potential therapy of Pseudomonas aeruginosa early infection in a mouse burn wound model

Antimicrobial resistance (AMR) constitutes a significant global threat to human health. In recent years, there has been a concerning surge in infections caused by multidrug-resistant bacteria, highlighting the pressing need to urgently explore novel and effective alternatives to conventional antibiotics. Antimicrobial peptides (AMPs) have emerged as a focal point of research, capturing significant attention as promising antimicrobial agents. In this study, we have identified a novel cationic antimicrobial peptide (AMP) named Scyreptin1-30, derived from the marine invertebrate Scylla paramamosain. The results showed that Scyreptin1-30 exhibits a broad-spectrum antimicrobial activity, demonstrating significant potency against both bacteria and fungi, and even against the clinically isolated multidrug-resistant bacteria Pseudomonas aeruginosa. Moreover, Scyreptin1-30 exhibited rapid bactericidal kinetic. The results of antibacterial mechanism showed that Scyreptin1-30 destroyed the integrity of bacterial membranes, leading to bacterial death and exhibited potent anti-biofilm activity against P. aeruginosa. The activity of Scyreptin1-30 against bacteria had a favorable thermal stability, displayed a certain ion tolerance, and showed no discernible cytotoxicity when assessed against both the mammalian cell line HEK293T and the fish cell lines ZF4. In an In vivo study, Scyreptin1-30 exhibited a remarkably reduction in the bacterial load caused by multidrug-resistant P. aeruginosa at the site of infection, and promoted wound healing in a mouse model of burn infection. This study indicated that Scyreptin1-30 holds promise as an effective antibacterial agent, potentially serving as a topical skin treatment against multidrug-resistant bacterial infections, including those caused by P. aeruginosa.

A facile and selective derivatization approach on kynurenine-NH2 in daptomycin, leading to the discovery of hexakynomycin to combat multidrug-resistant Gram-positive pathogens especially daptomycin-resistant bacteria

Wide-spread use of daptomycin unavoidably resulted in the emergence of daptomycin-resistant pathogens. In the hunt for more active daptomycin derivatives through medicinal chemistry studies, we established a concise semisynthetic approach to modify the L-Kyn13 on daptomycin specifically and effectively. Here, 19 novel derivatives with certain diversity were designed and synthesized to perform a comprehensive SAR study on this underestimated position. The optimal compound, termed "hexakynomycin", as the new generation of daptomycin-based antibiotic candidate exhibited 4->125-fold higher activity against methicillin-susceptible S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), vancomycin-intermediate resistant S. aureus (VISA), and vancomycin-resistant Enterococci (VRE), including daptomycin-resistant strains, compared with that of daptomycin. Greater membrane binding capacity rendered hexakynomycin better activity and special antibiotic property. Hexakynomycin also demonstrated a better pharmacokinetic profile, good safety features and good pharmacodynamics properties. This work provided an effective modification strategy aiming at daptomycin which provided significant insights and showed great promise for the next generation of daptomycin derivatives.

Green synthesis of silver nanoparticles derived from lemon and pomegranate peel extracts to combat multidrug-resistant bacterial isolates

BACKGROUND

Multidrug-resistant (MDR) bacteria are acknowledged as one of the main factors contributing to chronic illnesses and fatalities globally. Numerous diseases, including bloodstream infections, pneumonia, urinary tract infections, and surgical site infections, can be brought on by MDR bacteria. Therefore, a crucial topic of continuing research is the development of a novel and different treatment for MDR microbial pathogens. This work is introduce an alternative method for elimination of MDR bacterial isolates which are causative agents of urinary tract infection among people in Egypt. In our study, we need a novel strategy to combat MDR bacteria by green-synthesized metal nanoparticles (MNPs). That is due to the ability of MNPs to penetrate the cell wall and the cell membrane of gram-positive and gram-negative bacteria.

METHODS

Clinical isolates of MDR bacteria had their antibiotic susceptibility assessed before being molecularly identified using 16 s rRNA, sequencing, and phylogenetic analysis. Also, genetic profiles of isolated strains were performed using ISSR and SDS-PAGE. Finally, characterized plant-mediated silver nanoparticles derived from lemon and pomegranate peel extracts were evaluated against isolated multidrug-resistant bacterial stains.

RESULTS

In our present trial, one-hundred urine samples were collected from 71 females and 29 males complaining of UTI (urinary tract infection) symptoms. One-hundred microbial isolates were isolated, including 88-g negative and only 8-g positive bacteria in addition to four yeast isolates (Candida species). A total of 72% of the isolated bacteria showed MDR activity. The most prevalent MDR bacterial isolates (Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecalis, and Klebsiella pneumoniae) were identified through 16S rDNA PCR sequencing as with accession numbers OP741103, OP741104, OP741105, OP741106, and OP741107, respectively. Lemon and pomegranate-mediated silver nanoparticles [Ag-NPs] were characterized by UV spectroscopy, FTIR, XRD, and TEM with average size 32 and 28 nm, respectively. Lemon and pomegranate-mediated silver nanoparticles [Ag-NPs] showed an inhibitory effect on the selected five MDR isolates at MIC 50 and 30 µg/mL, respectively. These common bacterial isolates were also genetically examined using ISSR PCR, and their total protein level was evaluated using SDS-PAGE, showing the presence of distinct genetic and protein bands for each bacterial species and emphasizing their general and protein composition as a crucial and essential tool in understanding and overcoming MDR behavior in UTI patients.

CONCLUSIONS

Lemon and pomegranate-mediated silver nanoparticles [Ag-NPs] were found to have an inhibitory effect on MDR isolates. Therefore, the study suggests that [Ag-NPs] could be a potential treatment for MDR UTI infections caused by the identified bacterial species.

Distribution of multidrug-resistant bacterial infections in diabetic foot ulcers and risk factors for drug resistance: a retrospective analysis

Objective

To investigate the distribution, drug resistance and risk factors of multi-drug resistant bacterias (MDROs) in patients with Type 2 diabetic foot ulcers (DFU).

Method

The clinical data, foot secretions, pathogenic microorganisms and drug sensitivity tests of 147 patients with type 2 diabetes admitted to our department from January 2018 to December 2021 were analyzed. Patients were divided into two groups according to whether they had been infected with MDROs or not. Seventy-one cases were infected with MDROs as the case group, and the remaining 76 cases were the control group. Chi-square test and t-test were used to analyze the results of MDROs infection and DFU, and logistic multivariate regression was used to evaluate the risk factors of MDROs infection.

Results

A total of 71 strains were isolated from the MDROs-positive group, with the top three being Staphylococcus aureus (46.48%), Escherichia coli (22.53%), and Pseudomonas aeruginosa (18.31%), respectively. Logistic multifactorial regression analysis showed that history of previous antimicrobial exposure, neuroischemic wound, Wagner grade 3-5, and combined osteomyelitis were associated with Type 2 diabetic foot infection MDROs (P < 0.05).

Conclusion

Previous history of antimicrobial exposure, neuroischemic wounds, Wagner grade 3-5, and combined osteomyelitis are independent risk factors for MDROs, which can identify the risk factors for MDROs at an early stage and help to identify people at high risk of MDROs infection and take relevant comprehensive treatment in time to slow down the development of the disease.

Antimicrobial polymer-loaded hydrogels for the topical treatment of multidrug-resistant wound biofilm infections

Integration of antimicrobial polymeric nanoparticles into hydrogel materials presents a promising strategy to address multidrug-resistant biofilm infections. Here we report an injectable hydrogel loaded with engineered cationic antimicrobial polymeric nanoparticles (PNPs) for the effective topical treatment of severe wound biofilm infections. The PNPs demonstrated biofilm penetration and disruption, resulting in the eradication of resistant and persister cells that reside within the biofilm. Significantly, PNPs did not elicit resistance development even after multiple exposures to sub-therapeutic doses. In vitro studies showed PNPs significantly reduced prolonged inflammation due to infection and promoted fibroblast migration. These PNPs were then incorporated into Poloxamer 407 (P407) hydrogels and utilized as an inert carrier for PNPs to provide a controlled and sustained topical release of the antimicrobial nanoparticles at the wound area. In vivo studies using a mature (4-day) wound biofilm infection in a murine model mimicking severe human wound infections demonstrated provided 99% bacterial biofilm clearance and significantly enhanced wound healing. Overall, this work demonstrated the efficacy and selectivity of the antimicrobial polymer-loaded hydrogel platform as a topical treatment for difficult-to-treat wound biofilm infections.

Empiric antimicrobial therapy in the intensive care unit based on the risk of multidrug-resistant bacterial infection: a single-centre case‒control study of blood culture results in Japan

BACKGROUND

Infections and sepsis are the leading causes of death in intensive care units (ICUs). Antimicrobial agent selection is challenging because the intervention is directly related to the outcome, and the problem of antimicrobial resistance (AMR) must be considered. Therefore, in this study, we aimed to clarify the epidemiological data and examine whether the detection rate of multidrug-resistant (MDR) bacteria differed depending on the presence or absence of the risk of MDR bacterial infections to establish guidance regarding the choice of antimicrobial therapy for ICU patients.

METHODS

This retrospective case‒control study was performed in a single ICU in Japan. Patients admitted to the ICU who underwent blood culture (BC) analysis were considered for inclusion in this study; patients were at risk of MDR bacterial infections, and controls were not. The primary outcome measure was the detection rate of MDR bacteria in BCs collected from patients and controls. The secondary outcome measure was the selection rate of anti-Pseudomonas and anti-methicillin-resistant Staphylococcus aureus (MRSA) drugs for patients and controls.

RESULTS

Among the 1,730 patients admitted to the ICU during the study period, BCs were obtained from 186 patients, and 173 samples were finally included in the analysis (n = 129 cases; n = 44 controls). No MDR bacteria or Pseudomonas aeruginosa were detected in the controls (14 (11%) vs. 0 (0%)) (P = 0.014) However, there was no difference in empiric antimicrobials, including anti-MRSA (30 (23%) vs. 12 (27%)) (P = 0.592) and anti-Pseudomonas aeruginosa (61 (47%) vs. 16 (36%)) (P = 0.208) drugs, that were administered to the two groups.

CONCLUSIONS

Even in critically ill patients in the ICU, MDR bacteria are unlikely to be detected in patients without the risk of MDR bacterial infections. Therefore, for such patients, a strategy of starting empiric narrow-spectrum antimicrobial therapy rather than empiric broad-spectrum therapy should be considered. This strategy, in conjunction with daily updates of clinical and epidemiological data at each facility, will promote the appropriate use of antimicrobials and reduce the emergence of MDR bacteria in the ICU.

TRIAL REGISTRATION

None.

Antimicrobial Resistance in Organ Transplant Recipients

The overall burden of the main clinically relevant bacterial multidrug-resistant organisms (MDROs) (eg, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum β-lactamase producing or extended-spectrum cephalosporin-resistant Enterobacterales, carbapenem-resistant or carbapenemase-producing Enterobacterales, MDR Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii) in solid organ transplant (SOT) populations is summarized showing prevalence/incidence, risk factors, and impact on graft/patient outcome according to the type of SOT. The role of such bacteria in donor-derived infections is also reviewed. As for the management, the main prevention strategies and treatment options are discussed. Finally, nonantibiotic-based strategies are considered as future directions for the management of MDRO in SOT setting.

Update on Epidemiology and Outcomes of Infection in Pediatric Organ Transplant Recipients

Pediatric solid organ transplant (SOT) recipients are at risk for infection following transplantation. Data from adult SOT recipients are often used to guide prevention and treatment of infections associated with organ transplantation in children. This article highlights key recent pediatric SOT-specific publications for an array of infectious complications of organ transplantation. Attention is given to areas of need for future study.

Bacteriophage genome engineering for phage therapy to combat bacterial antimicrobial resistance as an alternative to antibiotics

Bacteriophages (phages) are viruses that mainly infect bacteria and are ubiquitously distributed in nature, especially to their host. Phage engineering involves nucleic acids manipulation of phage genome for antimicrobial activity directed against pathogens through the applications of molecular biology techniques such as synthetic biology methods, homologous recombination, CRISPY-BRED and CRISPY-BRIP recombineering, rebooting phage-based engineering, and targeted nucleases including CRISPR/Cas9, zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs). Management of bacteria is widely achieved using antibiotics whose mechanism of action has been shown to target both the genetic dogma and the metabolism of pathogens. However, the overuse of antibiotics has caused the emergence of multidrug-resistant (MDR) bacteria which account for nearly 5 million deaths as of 2019 thereby posing threats to the public health sector, particularly by 2050. Lytic phages have drawn attention as a strong alternative to antibiotics owing to the promising efficacy and safety of phage therapy in various models in vivo and human studies. Therefore, harnessing phage genome engineering methods, particularly CRISPR/Cas9 to overcome the limitations such as phage narrow host range, phage resistance or any potential eukaryotic immune response for phage-based enzymes/proteins therapy may designate phage therapy as a strong alternative to antibiotics for combatting bacterial antimicrobial resistance (AMR). Here, the current trends and progress in phage genome engineering techniques and phage therapy are reviewed.

Binary CuO\CoO nanoparticles inhibit biofilm formation and reduce the expression of papC and fimH genes in multidrug-resistant Klebsiella oxytoca

BACKGROUND AND AIM

Binary copper-cobalt oxide nanoparticles (CuO\CoO NPs) are modern kinds of antimicrobials, which may get a lot of interest in clinical application. This study aimed to detect the effect of the binary CuO\CoO NPs on the expression of papC and fimH genes in multidrug-resistant (MDR) isolates of Klebsiella oxytoca to reduce medication time and improve outcomes.

METHODS

Ten isolates of K. oxytoca were collected and identified by different conventional tests besides PCR. Antibiotic sensitivity and biofilm-forming ability were carried out. The harboring of papC and fimH genes was also detected. The effect of binary CuO\CoO nanoparticles on the expression of papC and fimH genes was investigated.

RESULTS

Bacterial resistance against cefotaxime and gentamicin was the highest (100%), while the lowest percentage of resistance was to amikacin (30%). Nine of the ten bacterial isolates had the ability to form a biofilm with different capacities. MIC for binary CuO\CoO NPs was 2.5 µg/mL. Gene expression of papC and fimH was 8.5- and 9-fold lower using the NPs.

CONCLUSION

Binary CuO\CoO NPs have a potential therapeutic effect against infections triggered by MDR K. oxytoca strains due to the NPs-related downregulation ability on the virulence genes of K. oxytoca.

Carbapenemase-producing Gram-negative bacteria in hospital wastewater, wastewater treatment plants and surface waters in a metropolitan area in Germany, 2020

Carbapenemase-producing bacteria (CPB) such as Klebsiella pneumoniae and Escherichia coli are causing hospital outbreaks worldwide. An important transfer route into the aquatic environment is the urban water cycle. We aimed to determine the presence of CPB in hospital wastewater, wastewater treatment plants (WWTPs) and surface waters in a German metropolitan area and to characterise these bacteria by whole-genome comparisons. During two periods in 2020, 366 samples were collected and cultivated on chromogenic screening media. Bacterial colonies were selected for species identification and PCR-based carbapenemase gene screening. Genomes of all detected CPB were sequenced and analysed for resistance gene content, followed by multilocus sequence typing (MLST) and core genome MLST (cgMLST) for K. pneumoniae and E. coli isolates. Carbapenemase genes were detected in 243 isolates, most of which belonged to genera/species Citrobacter spp. (n = 70), Klebsiella spp. (n = 57), Enterobacter spp. (n = 52) and E. coli (n = 42). Genes encoding KPC-2 carbapenemase were detected in 124 of 243 isolates. K. pneumoniae produced mainly KPC-2 and OXA-232 whereas E. coli harboured various enzymes (KPC-2, VIM-1, OXA-48, NDM-5, KPC-2 + OXA-232, GES-5, GES-5 + VIM-1, IMP-8 + OXA-48). Eight and twelve sequence types (STs) were identified for K. pneumoniae and E. coli, respectively, forming different clusters. The detection of numerous CPB species in hospital wastewater, WWTPs and river water is of concern. Genome data highlight a hospital-specific presence of distinct carbapenemase-producing K. pneumoniae and E. coli strains belonging to "global epidemic clones" in wastewater samples representing local epidemiology. The various detected CPB species including E. coli ST635, which is not known to cause human infections, could serve as reservoirs/vectors for the spread of carbapenemase genes in the environment. Therefore, effective pretreatment of hospital wastewater prior to discharge into the municipal wastewater system may be required, although swimming lakes do not appear to be a relevant risk factor for CPB ingestion and infection.

Phage and phage cocktails formulations

Antibiotic-resistant bacterial infection is a major global problem and can be life-threatening. Bacteriophages or phages can be substituted choice over traditional antibiotics treatments. Phages are natural obligate parasites viruses of bacteria, and they can infect and kill antibiotic-sensitive and -resistant bacteria. Further, phages can be utilised as antibacterial agents against various kinds of bacterial infectious diseases. As compared to antibiotics, phages can show a more variety of modes of action and can also be safe in several cases. Phages as a mixture (cocktail) of viral strains are usually used in clinical practices. Generally, to propagate phage cocktails, the individual phage is grown and then mixed to prepare phage cocktails. Antibiotic resistance and biofilm formation can be controlled through formulating phage cocktails that comprise phages infecting single species or by combining phages with non-phages (antibiotics), which may result in a broad spectrum of activity. This chapter briefly highlights the formulations and application of phage cocktails, which are being used to treat various bacterial infections.

Infection prevention and control programme and COVID-19 measures: Effects on hospital-acquired infections in patients with cirrhosis

Background & Aims

Bacterial infections affect survival of patients with cirrhosis. Hospital-acquired bacterial infections present a growing healthcare problem because of the increasing prevalence of multidrug-resistant organisms. This study aimed to investigate the impact of an infection prevention and control programme and coronavirus disease 2019 (COVID-19) measures on the incidence of hospital-acquired infections and a set of secondary outcomes, including the prevalence of multidrug-resistant organisms, empiric antibiotic treatment failure, and development of septic states in patients with cirrhosis.

Methods

The infection prevention and control programme was a complex strategy based on antimicrobial stewardship and the reduction of patient's exposure to risk factors. The COVID-19 measures presented further behavioural and hygiene restrictions imposed by the Hospital and Health Italian Sanitary System recommendations. We performed a combined retrospective and prospective study in which we compared the impact of extra measures against the hospital standard.

Results

We analysed data from 941 patients. The infection prevention and control programme was associated with a reduction in the incidence of hospital-acquired infections (17 vs. 8.9%, p <0.01). No further reduction was present after the COVID-19 measures had been imposed. The impact of the infection prevention and control programme remained significant even after controlling for the effects of confounding variables (odds ratio 0.44, 95% CI 0.26-0.73, p = 0.002). Furthermore, the adoption of the programme reduced the prevalence of multidrug-resistant organisms and decreased rates of empiric antibiotic treatment failure and the development of septic states.

Conclusions

The infection prevention and control programme decreased the incidence of hospital-acquired infections by nearly 50%. Furthermore, the programme also reduced the prevalence of most of the secondary outcomes. Based on the results of this study, we encourage other liver centres to adopt infection prevention and control programmes.

Impact and implications

Infections are a life-threatening problem for patients with liver cirrhosis. Moreover, hospital-acquired infections are even more alarming owing to the high prevalence of multidrug-resistant bacteria. This study analysed a large cohort of hospitalised patients with cirrhosis from three different periods. Unlike in the first period, an infection prevention programme was applied in the second period, reducing the number of hospital-acquired infections and containing multidrug-resistant bacteria. In the third period, we imposed even more stringent measures to minimise the impact of the COVID-19 outbreak. However, these measures did not result in a further reduction in hospital-acquired infections.

Hospital sanitary facilities on wards with high antibiotic exposure play an important role in maintaining a reservoir of resistant pathogens, even over many years

BACKGROUND

Hospitals with their high antimicrobial selection pressure represent the presumably most important reservoir of multidrug-resistant human pathogens. Antibiotics administered in the course of treatment are excreted and discharged into the wastewater system. Not only in patients, but also in the sewers, antimicrobial substances exert selection pressure on existing bacteria and promote the emergence and dissemination of multidrug-resistant clones. In previous studies, two main clusters were identified in all sections of the hospital wastewater network that was investigated, one K. pneumoniae ST147 cluster encoding NDM- and OXA-48 carbapenemases and one VIM-encoding P. aeruginosa ST823 cluster. In the current study, we investigated if NDM- and OXA-48-encoding K. pneumoniae and VIM-encoding P. aeruginosa isolates recovered between 2014 and 2021 from oncological patients belonged to those same clusters.

METHODS

The 32 isolates were re-cultured, whole-genome sequenced, phenotypically tested for their antimicrobial susceptibility, and analyzed for clonality and resistance genes in silico.

RESULTS

Among these strains, 25 belonged to the two clusters that had been predominant in the wastewater, while two others belonged to a sequence-type less prominently detected in the drains of the patient rooms.

CONCLUSION

Patients constantly exposed to antibiotics can, in interaction with their persistently antibiotic-exposed sanitary facilities, form a niche that might be supportive for the emergence, the development, the dissemination, and the maintenance of certain nosocomial pathogen populations in the hospital, due to antibiotic-induced selection pressure. Technical and infection control solutions might help preventing transmission of microorganisms from the wastewater system to the patient and vice versa, particularly concerning the shower and toilet drainage. However, a major driving force might also be antibiotic induced selection pressure and parallel antimicrobial stewardship efforts could be essential.

A graphene-oxide-based fluorometric assay for norA gene transcription in MRSA using Nb.BbvCI-assisted target recycling and T7 exonuclease-triggered cascade dual recycling signal amplification

We describe a graphene oxide (GO)-based bioassay for the fluorometric determination of norA gene transcription (mRNA) in methicillin-resistant Staphylococcus aureus (MRSA). This approach is based on Nb.BbvCI-assisted target recycling (NATR) and T7 exonuclease (T7 Exo)-triggered cascade dual-recycling signal amplification (TTCDRSA). The system included GO, a capture probe (CP), an assistant probe (AP), two carboxyfluorescein (FAM)-labeled hairpins (HP1 and HP2), endonuclease Nb.BbvcI, and exonuclease T7. In the presence of a target, AP, together with the target RNA, can hybridise with CP via partial complementarity to one another and open its hairpin structure to form a triple complex that is recognised by Nb.BbvCI. Once the CP is cleaved, the released AP and target RNA can walk on the carboxylated graphene oxide (CGO) surface to bind with another CP which induces the next round of cleavage, accumulating many trigger probes (TPs). The TPs then activate TTCDRSA with the assistance of T7 Exo, HP1, and HP2 to produce large amounts of free FAMs. These free FAMs are repelled by GO and exhibit enhanced fluorescence signals at excitation/emission wavelengths of 480/514 nm. The limit of detection (LOD) of the bioassay was calculated to be 0.37 fM, and the linear range of the method ranged from 1 fM to 1 nM. More importantly, the bioassay also exhibited high sensitivity and selectivity for target RNA detection in real samples, which may open a new promising avenue for monitoring drug efflux and studying the mechanisms of drug actions.

Characterization of a broad-spectrum endolysin rLysJNwz and its utility against Salmonella in foods

Salmonella is a common foodborne pathogen worldwide. The use of bacteriophage-encoded endolysins as antimicrobial agents is a promising approach for controlling pathogenic contamination. In this context, a recombinant endolysin named rLysJNwz, consisting of a single domain falling with the L-alanogyl-D-glutamate peptidase-like family, was cloned, expressed, and characterized. The yield of rLysJNwz was about 25 mg/L. Synergy between 7.5 μg/mL rLysJNwz and 0.5 mmol/L EDTA could decrease the viable counts of Salmonella NCTC 8271 by 93.28%. A synergistic effect between rLysJNwz and polymyxin B was demonstrated, exhibiting the MIC of polymyxin B decreased by twofold. Specifically, rlysJNwz had strong thermostability at temperatures (4-95 °C) and maintained high activity at pHs from 5.0 to 11.0. rlysJNwz was a metal ion-dependent peptidase, which activated by divalent metal ions such as Zn²⁺, Mn²⁺, or Ca²⁺. Moreover, it was also found that the synergism of rlysJNwz and EDTA had bactericidal activities against a broad range of Gram-negative bacteria, including several multidrug-resistant bacteria. The application of rLysJNwz combined with EDTA was evaluated on contaminated eggs and lettuce for 60 min, displaying more than 86.7% and 86.5% reduction of viable Salmonella, respectively. Hence, these results suggest that rLysJNwz is a potential antibacterial agent to control Salmonella, especially antibiotic-resistant pathogen contamination in the field of food safety. KEY POINTS: • rLysJNwz shows lytic activities against a broad range of Gram-negative bacteria. • Endolysin rLysJNwz is a stable metalloenzyme and has high thermostability. • rLysJNwz and 0.5 mmol/L EDTA synergistically inactivate Salmonella on eggs and lettuce.

Association Between Multidrug-Resistant Bacteria and Mortality in Critically Ill Patients

INTRODUCTION

Multidrug-resistant bacteria (MDRB) carriage may impact the outcomes of intensive care unit (ICU) patients. In this study, we aimed to assess the effect of MDRB-related infection and colonization on the day 60 mortality rate.

METHODS

We conducted a retrospective, observational study in a single university hospital ICU. From January 2017 to December 2018, we screened all patients admitted to the ICU for at least 48 h for MDRB carriage. The primary outcome was the mortality rate on day 60 after MDRB-related infection. The secondary outcome was the mortality rate on day 60 of non-infected but colonized patients with MDRB. We considered the effect of potential confounders, such as the occurrence of septic shock, inadequate antibiotic therapy, Charlson score, and life-sustaining limitation order.

RESULTS

We included 719 patients during the aforementioned period; of this number, 281 (39%) had a microbiologically documented infection. MDRB was found in 40 (14%) patients. The crude mortality rate in the MDRB-related infection group was 35% vs. 32% in the non-MDRB-related infection group (p = 0.1). Logistic regression showed that MDRB-related infection was not associated with excess mortality, with an odds ratio of 0.52 and a 95% confidence interval from 0.17 to 1.39 (p = 0.2). Charlson score, septic shock, and life-sustaining limitation order were significantly associated with an increased mortality rate on day 60. No effect of MDRB colonization on mortality rate on day 60 was highlighted.

CONCLUSION

MDRB-related infection or colonization was not associated with an increased mortality rate on day 60. Other confounders, such as comorbidities, may account for a higher mortality rate.

A novel antimicrobial peptide YS12 isolated from Bacillus velezensis CBSYS12 exerts anti-biofilm properties against drug-resistant bacteria

Nowadays, the abuse of antibiotics has led to the rise of multi-drug-resistant bacteria. Antimicrobial peptides (AMPs), with broad-spectrum antimicrobial activity have attracted considerable attention as possible alternatives to traditional antibiotics. In this work, we aimed to evaluate the antimicrobial and anti-biofilm activity of an antimicrobial peptide designed as YS12 derived from Bacillus velezensis CBSYS12. The strain CBSYS12 was isolated from Korean food kimchi and purified followed by ultrafiltration and sequential chromatographic methodology. Hereafter, Tricine SDS-PAGE revealed a single protein band of around 3.3 kDa that was further confirmed in situ inhibitory activity of the gel. A similar molecular weight (~ 3348.4 Da) protein also appeared in MALDI-TOF confirming the purity and homogeneity of peptide YS12. Intriguingly, YS12 revealed a strong antimicrobial activity with a minimum inhibitory concentration (MIC) value ranging from 6 to 12 μg/ml for both Gram-positive and Gram-negative bacteria, such as E. coli, P. aeruginosa, MRSA 4-5, VRE 82, and M. smegmatis. We also determined the mode of action of the peptide against pathogenic microorganisms using different fluorescent dyes. In addition, the anti-biofilm assay demonstrated that peptide YS12 was able to inhibit biofilm formation  around 80% for both bacterial strains E. coli and P. aeruginosa at 80 µg/ml. Notably, YS12 exhibited a greater biofilm eradication activity than commercial antibiotics. In summary, our study proposed that peptide YS12 may be used as a promising therapeutic agent to overcome drug and biofilm-related infections.

Impact of the "Zero Resistance" program on acquisition of multidrug-resistant bacteria in patients admitted to Intensive Care Units in Spain. A prospective, intervention, multimodal, multicenter study

OBJECTIVE

To assess the impact of a multimodal interventional project ("Zero Resistance") on the acquisition of multidrug-resistant bacteria (MDR-B) during the patient's ICU stay.

DESIGN

Prospective, open-label, interventional, multicenter study.

SETTING

103 ICUs.

PATIENTS

Critically ill patients admitted to the ICUs over a 27-month period.

INTERVENTIONS

Implementation of a bundle of 10 recommendations to prevent emergence and spread of MDR-B in the ICU.

MAIN VARIABLE OF INTEREST

Rate of patients acquiring MDR-B during their ICU stay, with differentiation between colonization and infection.

RESULTS

A total of 139,505 patients were included. In 5409 (3.9%) patients, 6020 MDR-B on ICU admission were identified, and in 3648 (2.6%) patients, 4269 new MDR-B during ICU stay were isolated. The rate of patients with MDR-B detected on admission increased significantly (IRR 1.43, 95% CI 1.31-1.56) (p<0.001) during the study period, with an increase of 32.2% between the initial and final monthly rates. On the contrary, the rate of patients with MDR-B during ICU stay decreased non-significantly (IRR 0.93, 95% CI 0.83-1.03) (p=0.174), with a 24.9% decrease between initial and final monthly rates. According to the classification into colonization or infection, there was a highly significant increase of MDR-B colonizations detected on admission (IRR 1.69, 95% CI 1.52-1.83; p<0.0001) and a very significant decrease of MDR-B-infections during ICU stay (IRR 0.67, 95% CI 0.57-0.80, p<0.0001).

CONCLUSIONS

The implementation of ZR project-recommendations was associated with a significantly reduction an infection produced by MDR-B acquired during the patient's ICU stay.

Strategic insight into enhanced photocatalytic remediation of pharmaceutical contaminants using spherical CdO nanoparticles in visible light region

The sustainable control of pharmaceutical micropollutants in water and wastewater environments is a great challenge in the 21st century. To address these issues, unique CdO nanoparticles (NPs) were synthesized using a facile hydrothermal approach and investigated for photocatalytic control of the antibiotic tetracycline, multidrug-resistant bacteria (MDRB), and total coliform in the wastewater effluent. The NPs were characterized using a range of techniques and it exhibited a spherical-like crystal structure with a mean size of 40 nm. The vibrational stretching mode of 1419 cm^-1 confirmed the formation of Cd-O (M - O). The synthesis protocol formed smoother surfaces and 1.88 eV band gap energy of CdO NPs, inducing excellent photocatalytic activity under visible LED light (blue and white) irradiation. The optimal catalyst dose and pH were 100 mg/L and 8-9, respectively. Blue light proved more effective than white light, resulting in 28% higher efficiency (93 ± 0.47%) in tetracycline degradation than white light under an identical intensity (20 mW/cm²). White light required a four-fold higher light intensity (80 mW/cm²) than blue light to induce comparable photocatalytic MDRB inactivation. Bacterial cell lysis by the photocatalytic treatment was confirmed by transmission electron microscopy (TEM). The used catalyst was easily recovered by 5 min of centrifugation and re-used without any noticeable change in the photocatalytic decomposition. The trapping experiment revealed that the CdO-based NPs contributed primarily to the generation of •O₂^- and •OH radicals (Type I), but the •O₂^- radicals were the dominant reactive oxygen species (ROS) in the photocatalytic process.

Myconanoparticles Break Antibiotic Resistance in Staphylococcus aureus and Acinetobacter baumannii

In this current study, the extracts of endophytic fungi (Aspergillus niger) were utilized to synthesize the silver nanoparticles (AnNps). In silico screening was carried out by docking secondary metabolites of Aspergillus niger with drug-resistant proteins such as penicillin-binding protein (pbp2a) and clumping factor A of Staphylococcus aureus, penicillin-binding protein (PBP3), and outer membrane protein of Acinetobacter baumannii. The molecular docking analysis revealed the interaction between secondary metabolites of Aspergillus niger with virulence factors of the pathogenic bacteria. AnNps are characterized by various physicochemical methods to determine the size, shape, and stability. Antibacterial efficacy of synthesized nanoparticles (AnNps) was screened in clinical pathogens. AnNp treatment significantly reduced the growth of MDR pathogens. The results suggested that AnNps can be incorporated to produce antimicrobial agents to control drug resistant pathogenic bacteria.

Incorporation of plasma Vitamin C levels to modified nutritional risk in critically ill score as the novel Vitamin C nutritional risk in critically ill score in sepsis subjects as an early predictor of multidrug-resistant bacteria: A prospective observational study

Background

On intensive care unit (ICU) admission, it is difficult to predict which patient may harbor multidrug-resistant (MDR) bacteria. MDR is the nonsusceptibility of bacteria to at least one antibiotic in three or more antimicrobial categories. Vitamin C inhibits bacterial biofilms, and its incorporation into the modified nutritional risk in critically ill (mNUTRIC) scores may help predict MDR bacterial sepsis early.

Methods

A prospective observational study was conducted on adult subjects with sepsis. Plasma Vitamin C level was estimated within 24 h of ICU admission, and it was incorporated into the mNUTRIC score (designated as Vitamin C nutritional risk in critically ill [vNUTRIC]). Multivariable logistic regression was performed to determine if vNUTRIC was an independent predictor of MDR bacterial culture in sepsis subjects. The receiver operating characteristic curve was plotted to determine the vNUTRIC cutoff score for predicting MDR bacterial culture.

Results

A total of 103 patients were recruited. The bacterial culture-positive sepsis subjects were 58/103, with 49/58 culture-positive subjects having MDR. The vNUTRIC score on ICU admission in the MDR bacteria group was 6.71 ± 1.92 versus 5.42 ± 2.2 in the non-MDR bacteria group (P = 0.003, Independent Student's t-test). High vNUTRIC score ≥6 on admission is associated with MDR bacteria (P = 0.042 Chi-Square test), and is a predictor of MDR bacteria (P = 0.003, AUC 0.671, 95% confidence interval [0.568-0.775], sensitivity 71%, specificity 48%). Logistic regression showed that the vNUTRIC score is an independent predictor of MDR bacteria.

CONCLUSION

High vNUTRIC score (≥6) on ICU admission in sepsis subjects is associated with MDR bacteria.

Cocrystallizing and Codelivering Complementary Drugs to Multidrugresistant Tuberculosis Bacteria in Perfecting Multidrug Therapy

Bacteria cells exhibit multidrug resistance in one of two ways: by raising the genetic expression of multidrug efflux pumps or by accumulating several drug-resistant components in many genes. Multidrug-resistive tuberculosis bacteria are treated by multidrug therapy, where a few certain antibacterial drugs are administered together to kill a bacterium jointly. A major drawback of conventional multidrug therapy is that the administration never ensures the reaching of different drug molecules to a particular bacterium cell at the same time, which promotes growing drug resistivity step-wise. As a result, it enhances the treatment time. With additional tabletability and plasticity, the formation of a cocrystal of multidrug can ensure administrating the multidrug chemically together to a target bacterium cell. With properly maintaining the basic philosophy of multidrug therapy here, the synergistic effects of drug molecules can ensure killing the bacteria, even before getting the option to raise the drug resistance against them. This can minimize the treatment span, expenditure and drug resistance. A potential threat of epidemic from tuberculosis has appeared after the Covid-19 outbreak. An unwanted loop of finding molecules with the potential to kill tuberculosis, getting their corresponding drug approvals, and abandoning the drug after facing drug resistance can be suppressed here. This perspective aims to develop the universal drug regimen by postulating the principles of drug molecule selection, cocrystallization, and subsequent harmonisation within a short period to address multidrug-resistant bacteria.