The central role of the gut in intensive care

Critically ill patients undergo early impairment of their gut microbiota (GM) due to routine antibiotic therapies and other environmental factors leading to intestinal dysbiosis. The GM establishes connections with the rest of the human body along several axes representing critical inter-organ crosstalks that, once disrupted, play a major role in the pathophysiology of numerous diseases and their complications. Key players in this communication are GM metabolites such as short-chain fatty acids and bile acids, neurotransmitters, hormones, interleukins, and toxins. Intensivists juggle at the crossroad of multiple connections between the intestine and the rest of the body. Harnessing the GM in ICU could improve the management of several challenges, such as infections, traumatic brain injury, heart failure, kidney injury, and liver dysfunction. The study of molecular pathways affected by the GM in different clinical conditions is still at an early stage, and evidence in critically ill patients is lacking. This review aims to describe dysbiosis in critical illness and provide intensivists with a perspective on the potential as adjuvant strategies (e.g., nutrition, probiotics, prebiotics and synbiotics supplementation, adsorbent charcoal, beta-lactamase, and fecal microbiota transplantation) to modulate the GM in ICU patients and attempt to restore eubiosis.

Application of antimicrobial photodynamic therapy to treat subgingival multidrug-resistant bacterial infections in ICU patients

BACKGROUND

Drug-resistant bacterial infections have received much attention in recent years. Antimicrobial photodynamic therapy (aPDT) is an effective antimicrobial strategy. This study aimed to evaluate the therapeutic effect of methylene blue (MB)-mediated aPDT against subgingival multidrug-resistant (MDR) bacterial infections in intensive care unit (ICU) patients.

METHODS

Eighty-three patients who were hospitalized in the ICU of the Second Affiliated Hospital of Nanchang University from July 2019 to June 2021 were selected. The intraoral partitioned control test was conducted. Teeth that met the criteria were selected from different quadrants of the same patient, randomly divided into three groups, namely, A, B, and C, and treated with aPDT, chlorhexidine gargle, or normal saline. The counts of MDR bacteria in the gingival crevicular fluid were assessed in the different groups at different time points before and after treatment.

RESULTS

The MDR bacterial count decreased immediately after aPDT and was significantly different from that in the chlorhexidine gargle rinse group and the normal saline rinse group (P<0.05). There was no significant difference among the three groups at 6, 12, and 24 hours after treatment (P>0.05).

CONCLUSION

aPDT can be used to treat subgingival MDR bacterial infections, but the long-term effects of treatment need to be further studied.

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

Background

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

Methods

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

Results

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

Conclusions

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

Gallium-Based Nanoplatform for Combating Multidrug-Resistant Pseudomonas aeruginosa and Postoperative Inflammation in Endophthalmitis Secondary to Cataract Surgery

Postcataract endophthalmitis (PCE), a devastating complication following cataract surgeries, is one of the most crucial diseases causing irreversible eye blindness. Pseudomonas aeruginosa (PA), a multiple-drug-resistance (MDR) pathogen, always leads to uncontrolled infection and severe inflammation in PCE that can be difficult to treat by antibiotics. Therefore, it is urgent to develop new feasible strategies composed of both antibacterial and anti-inflammatory capabilities. Here, we report a multifunctional non-antibiotic nanoplatform (Ga-mSiO₂-BFN) comprised of clinically approved gallium, mesoporous silica, and bromfenac (BFN) as a co-modified release system to simultaneously eradicate MDR-PA infection and cure inflammation for PCE. The released gallium ions can disrupt bacterial iron metabolism. Meanwhile, the simultaneously released BFN can suppresses the inflammation both postoperation and postinfection of PCE. In the PCE rabbit model, the slit-lamp dispersion and retro-illumination micrograph, ophthalmic clinical grading, and etiological histopathology analysis demonstrated that Ga-mSiO₂-BFN could eradicate the MDR infection and alleviate the secondary inflammation from MDR-PA infection. Moreover, both cellular biocompatibility and in vivo animal model application verified the biocompatibility. A potential antibacterial mechanism implicated in the antibacterial action was demonstrated by comprehensive assays of iron antagonism evolutionary curve, colony autofluorescence, polymerase chain reaction, and electron microscopy, showing a repressing siderophore peptide pyoverdine, pyoverdine synthetase D, and interfering with bacterial DNA synthesis. All composites of our nanoplatform were FDA approved, making the Ga-mSiO₂-BFN as a potentially promising therapeutic approach for treating MDR-PA in PCE accompanying satisfactory prognosis and prospects for clinical translations.

Photodynamic inactivation of multidrug-resistant bacteria in wastewater effluent using green phytochemicals as a natural photosensitizer

The control of multidrug-resistant bacteria (MDRB) is a great challenge in the 21st century. Photodynamic treatment (PDT) is one of the promising approaches to control MDRB. In the process, powerful oxidants such as reactive oxygen species (ROS) are produced, which cause cytotoxic damage and cell death of bacteria. This study examined a new and environment-friendly strategy for the photodynamic inactivation of two MDRB (Escherichia coli and Staphylococcus aureus) and total coliform (TC) in wastewater effluent using two phytochemicals, pyrogallol (PGL) and terpinolene (TPN), along with white and blue light-emitting diode (LED) light. Fourier-transform infrared spectroscopy (FTIR) of the phytochemicals confirmed the presence of different phenolic and aromatic compounds, which can enhance the generation of ROS alongside inactivating the bacterial cells. In the PDT process, white LED light was more active in controlling MDRB than blue LED light. After 80 min irradiation with white LED light (17 mW/cm²), the MDRB bacteria were eradicated completely at a minimum inhibitory concentration (MIC) dose (0.156 mg/mL for E. coli and 0.078 mg/mL for S. aureus) of PGL. In addition, light intensity was an important parameter in photodynamic disinfection. The TC in the secondary effluent was inactivated completely by both phytochemicals after 60 min of exposure to white LED light with an intensity of 80 mW/cm². The photosensitizing activity of phytochemicals was analyzed by a bactericidal and imidazole-RNO assay. These assays showed that PGL contributed to the generation of •OH radicals, whereas TPN produced ¹O₂ in the PDT process. Transmission electron microscopy (TEM) confirmed bacterial cell disruption after treatment. Overall, PDT using the phytochemicals as PS is a sustainable approach to control the MDRB and TC in wastewater successfully.

Characteristics of bacterial infections and prevalence of multidrug-resistant bacteria in hospitalized patients with liver cirrhosis in Germany

INTRODUCTION AND OBJECTIVES

Bacterial infections are associated with a dismal prognosis in patients with liver cirrhosis. Data on their prevalence and the associated pathogen spectra in Germany are scarce. This study aimed to evaluate the impact of bacterial infections on mortality in hospitalized patients with liver cirrhosis and to analyze the prevalence of multidrug-resistant (MDR) bacteria in a German tertiary care center.

PATIENTS AND METHODS

Consecutive, non-electively hospitalized patients with liver cirrhosis were enrolled in this study between 03/2019-06/2021. All patients underwent clinical, laboratory and microbiological testing to detect potential bacterial infections. Patients were followed for 30 days regarding the composite endpoint of death or liver transplantation (mortality).

RESULTS

In total, 239 patients were recruited (median MELD 18). Bacterial infection was detected in 81 patients (33.9%) at study inclusion. A total of 70 patients (29.3%) developed a hospital-acquired infection. When comparing community-acquired and hospital-acquired infections, the pathogen pattern shifted from a gram-negative to a more gram-positive spectrum and showed an increase of Staphylococcus spp.. MDR bacteria were detected in seven infected patients (5.8%). 34 patients reached the composite endpoint during 30-days follow-up. In multivariable logistic regression analysis, the presence of infection during hospitalization remained independently associated with higher mortality (OR 2.522, 95% CI 1.044 - 6.091, p = 0.040).

CONCLUSIONS

This study demonstrates that bacterial infections are common in hospitalized patients with liver cirrhosis in Germany and are a major determinant of short-term mortality. Our data highlight the importance of regional differences in MDR bacteria and may guide physicians' decision-making regarding calculated antibiotic treatment.

Treatment of severe multi-drug resistant Pseudomonas aeruginosa infections

Pseudomonas aeruginosa is the microorganism most frequently involved in the main ICU-acquired infections, with special importance in ventilator associated pneumonia. Its importance lies, in addition to its high incidence in critically ill patients, in the severity of the infections it causes and in the difficulty of its antimicrobial treatment, directly related to the high percentage of resistance to antibiotics classically considered first-line. New active antibiotics have recently been developed against Pseudomonas aeruginosa, even against multi-drug resistant strains. This review analyzes both the differential characteristics of Pseudomonas aeruginosa infections and the new therapeutic options, focusing on multi-drug resistant Pseudomonas aeruginosa.

A New Saharan Strain of Streptomyces sp. GSB-11 Produces Maculosin and N-acetyltyramine Active Against Multidrug-Resistant Pathogenic Bacteria

Multi-resistant bacterial pathogens are a major public health problem for treating nosocomial infections owing to their high resistance to antibiotics. The objective of this research was to characterize the bioactive molecules secreted by a novel moderately halophilic actinobacterium strain, designated GSB-11, exhibiting a strong antagonistic activity against several multidrug-resistant pathogenic bacteria. This potential strain was identified by phenotypic, genotypic (16S rRNA), and phylogenetic analyses. GSB-11 was related to "Streptomyces acrimycini" NBRC 12736 ^T with 99.59% similarity. Molecular screening by PCR assay demonstrated that the strain possesses two biosynthetic genes coding for NRPS and PKS-II. Two active compounds GSB11-6 and GSB11-7 were extracted from the cell-free culture supernatant of Bennett medium and purified using reversed-phase HPLC. According to spectrometric (mass spectrum) and spectroscopic (¹H NMR, ¹³C NMR, ¹H-¹H COSY, and ¹H-¹³C HMBC) spectra analyses, the compounds GSB11-6 and GSB11-7 were identified to be maculosin and N-acetyltyramine, respectively. Their minimum inhibitory concentrations (MIC) revealed interesting values against certain multidrug-resistant pathogenic bacteria. They were between 5 and 15 mg/mL for GSB11-6, 10 and 30 mg/mL for GSB11-7. To our best knowledge, this is the first study of these active substances isolated from "Streptomyces acrimycini" showing an interesting antibacterial activity. Therefore, these essential compounds could be candidates for future research against multidrug-resistant bacteria.

Cytotoxic screening and antibacterial activity of Withaferin A

Cancer and bacterial infections are among the leading causes of death worldwide. Plant-derived bioactive compounds constitute promising alternatives for development of new therapeutics. This study aimed at evaluating the biological activity of Withaferin A using 6 tumor cell lines: A549 (lung cancer), U87MG (glioblastoma), SH-SY5Y (neuroblastoma), B16-F10 (mouse melanoma), HeLa (uterine colon cancer) and K562 (chronic myeloid leukemia). In addition, 17 other standard bacterial strains and several multidrug resistant bacteria (MDR) clinical isolates were examined. Cell viability was assessed using the following assays: MTT, neutral red, and dsDNA PicoGreen®. Further, oxidative stress was measured by quantification of reactive oxygen species (ROS) production. The activity against bacteria was determined by the minimum inhibitory concentration (MIC), minimum bacterial concentration (CBM) and antibiofilm activity in the production of strains. Withaferin A was effective, as evidenced by its cytotoxic activity in tumor cell lines, enhanced ROS production in tumor cells and bactericidal and antibiofilm activity. Data demonstrated that Withaferin A may be therapeutically considered as an antitumor and antibacterial agent.

Causative agents of bloodstream infections in two Croatian hospitals and their resistance mechanisms

Blood samples were collected alongside with routine blood cultures (BC) from patients with suspected sepsis, to evaluate the prevalence of different causative agents in patients with bacteraemia. Among 667 blood samples, there were 122 positive BC (18%). Haemoglobin content, platelet number, and systolic blood pressure values were significantly lower in patients with positive BC, whereas serum lactate levels, CRP, creatinine and urea content were significantly higher in patients with positive BC. The rate of multidrug (MDR) or extensively drug resistant (XDR) bacteria was 24% (n = 29): Klebsiella pneumoniae (9), Pseudomonas aeruginosa (9), Acinetobacter baumannii (4), Escherichia coli (1), vancomycin resistant Enterococcus spp (VRE) (3), and methicillin-resistant Staphylococcus aureus MRSA (3). The dominant resistance mechanisms were the production of extended-spectrum β-lactamases, OXA-48 carbapenemase, and colistin resistance in K. pneumoniae, VIM metallo-β-lactamases in P. aeruginosa and OXA-23-like oxacillinases in A. baumannii. The study revealed high rate of MDR strains among positive BCs in Zagreb, Croatia.

Anti-inflammatory effect, antibiotic potentiating activity against multidrug-resistant strains of Escherichia coli and Staphylococcus aureus, and evaluation of antibiotic resistance mechanisms by the ibuprofen derivative methyl 2-(-4-isobutylphenyl)propanoate

The prevalence of multidrug-resistant (MDR) bacteria and the limited efficacy of current available antibiotics cause every year approximately 700 000 deaths per year. This study aimed to evaluate the anti-inflammatory effect and antibacterial potential of the ibuprofen derivative Methyl 2-(-4-isobutylphenyl)propanoate (MET-IBU). The molecular structure of MET-IBU was confirmed by Nuclear Magnetic Resonance (NMR) and, Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) spectroscopy. Our in vivo study using adult zebrafish model demonstrated that the ibuprofen derivative MET-IBU also possesses anti-inflammatory effect, and in vitro antibacterial activity assays showed that in the association of ampicillin, norfloxacin, and gentamicin with MET-IBU occurred reduction in the minimum inhibitory concentration (MIC) for MDR bacterial strains of Escherichia coli 06 and Staphylococcus aureus 10, indicating a potentiating in the growth inhibition of these pathogenic bacteria. Regarding the strain of Staphylococcus aureus K2068 (overexpressing mepA gene), a potentiation of ethidium bromide was found in the association with MET-IBU, indicating the action of this compound on the efflux pump mechanism present in this strains. This result corroborates the molecular docking study that indicated a high affinity of the MET-IBU with the MepA efflux pump. It was also noticed an antibiotic potentiating activity in the association MET-IBU with norfloxacin against strains of Staphylococcus aureus 1199B (overexpressing norA gene) when compared to the norfloxacin control. This enhanced antibiotic effect of MET-IBU is associated with a second resistance mechanism, which is due to the modification in the topoisomerase enzyme. These results bring attention to the ibuprofen derivative MET-IBU as possible candidate for the development of new options for the treatment of bacterial infections with protective anti-inflammatory action.

Dual antimicrobial-loaded biodegradable nanoemulsions for synergistic treatment of wound biofilms

Wound biofilm infections caused by multidrug-resistant (MDR) bacteria constitute a major threat to public health; acquired resistance combined with resistance associated with the biofilm phenotype makes combatting these infections challenging. Biodegradable polymeric nanoemulsions that encapsulate two hydrophobic antimicrobial agents (eugenol and triclosan) (TE-BNEs) as a strategy to combat chronic wound infections are reported here. The cationic nanoemulsions efficiently penetrate and accumulate in biofilms, synergistically eradicating MDR bacterial biofilms, including persister cells. Notably, the nanoemulsion platform displays excellent biocompatibility and delays emergence of resistance to triclosan. The TE-BNEs are active in an in vivo murine model of mature MDR wound biofilm infections, with 99% bacterial elimination. The efficacy of this system coupled with prevention of emergence of bacterial resistance highlight the potential of this combination platform to treat MDR wound biofilm infections.

Phage-mimicking nanoagents for rapid depolymerase specificity screening against multidrug resistant bacteria

With the rise of drug resistance, bacteriophages and bacteriophage-derived proteins may become an efficient successor to traditional antibiotics. While the enormous natural diversity of the phages allows matching virtually any bacteria, identification of the potentially life-saving phage is currently a tedious and time-consuming challenge that often cannot be performed within a reasonable time. Here we show a rapid 1-min bacteriophage screening assay based on specially constructed phage-mimicking nanoagents and surface plasmon resonance effect. Within the assay, a panel of phage-mimicking gold nanoparticles, possessing the specificity and enzymatic activity of a particular phage, is mixed with a suspension of the bacteria of interest. The spectral behaviour of the assay mix allows measurement of two critical parameters of the nanoagents and the corresponding bacteriophages: 1) direct assessment of their specificity due to convergence of the particles on the cell walls, and more importantly, 2) real-time evaluation of their enzymatic activity for the destruction of the cell capsule via detection of nanoagent detachment from the surface of bacteria. The proposed assay overcomes the current time limitations of the phage-bacteria matching procedures and thereby can facilitate faster development and adoption of phage-based therapies as a much-needed alternative to traditional antibiotics.

Green phytoextracts as natural photosensitizers in LED-based photodynamic disinfection of multidrug-resistant bacteria in wastewater effluent

The photodynamic treatment (PDT) process is a promising technology to control emerging pollutants and antimicrobial resistance problems in the water environment. The reactive oxygen species (ROS) produced when natural and nontoxic photosensitizers (PS) are exposed to light are the key functional components of the PDT process that can effectively achieve microbial inactivation with minimal negative impact. This study examined the application of green phytoextracts from two plants, Chamaecyparis obtusa and Moringa oleifera, as natural photosensitizers for the white light-emitting diode (LED) based photodynamic disinfection of multidrug-resistant (MDR) and total coliforms (TC) from secondary effluent in full-scale municipal wastewater treatment plants. Gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy showed that the phytoextracts contained 57 compounds, particularly aromatic and phenolic hydroxyl compounds. The phytoextracts showed an excellent activity as a PS compared to the intrinsic antibacterial effect. Under a light intensity of 17 mW/cm², the complete inactivation (6.55 Log CFU/mL) was observed at an irradiation time of 100 min for Escherichia coli ART-2 and 80 min for Staphylococcus aureus, meaning that E. coli was resistant. The light intensity was an important factor influencing photodynamic disinfection. For the complete disinfection of TC satisfying the water reclamation regulation, the irradiation time requirement was 20 min under a light intensity of 80 mW/cm². During the photodynamic reaction, a significant amount of ROS was generated from the phytoextracts as the light irradiation time was increased. The major ROS was singlet oxygen (¹O₂, Type II) during the initial 40 min of reaction time and hydroxyl radical (•OH, Type I) after 40 min until complete inactivation.

The Tagetes lucida Cav. essential oil and the mixture of its main compounds are antibacterial and modulate antibiotic resistance in multi-resistant pathogenic bacteria

We evaluated an essential oil (EO) of Tagetes lucida Cav. and the mixture of its main compounds against multi-drug resistant bacteria. We found that EO and the partially reconstituted blend of its main components have antibacterial activity and inhibit antibiotic resistance (ampicillin, chloramphenicol, nalidixic acid, vancomycin, and imipenem) in strains of Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa HIM-MR01. The T. lucida EO alone or added to the antibiotics showed antimicrobial activity against S. aureus and P. aeruginosa. The EO main bioactive compounds were methyl eugenol (46.15%), estragole (32.93%), linalool (2.48%), and geraniol (0.33%). The mixture (PREO) of those compounds at those proportions inhibited the growth of P. aeruginosa in 45% at 683.62 µg mL^-1 and that of S. aureus in 51.7% at 39.04 µg mL^-1 . The PREO had higher antibacterial and modulatory activities than the original EO. In conclusion, we overcame the unpredictability of EO activity (due to their natural variability) by determining which EO components inhibited bacteria and then producing a PREO to generate a reproducible mixture with predictable antibacterial and modulation of resistance activities. Thus, the PREO, and its components, show potential as alternatives to manage multidrug-resistant pathogens.

The efficiency of cleaning in intensive care units: A systematic review

OBJECTIVES

This review aims to analyze the studies on cleaning practices and the efficiency of the cleaning carried out in environments that have a great risk of resistant microorganism infection, such as intensive care units.

METHODS

In this study, a retrospective literature review was undertaken of the relevant publications between the years 2005 and 2020, using the keywords "Cross Infection, Infection Control, Multidrug-Resistant Bacteria, Intensive Care, Room Cleaning, Environmental Cleaning, Hospital-Associated Infection"; using the international databases Pubmed, CINAHL and EBSCO and domestic database ULAKBIM on search engines. Titles and abstracts of all relevant articles found on electronic searches were reviewed by the researchers independently. The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guideline and Patient, Intervention, Comparison, Outcomes, Study design model were used in analysing the studies.

RESULTS

The selected studies were reviewed in four main categories: Materials used in cleaning, the period between taking environmental samples, cleaning methods, and the efficiency of cleaning. Among the studies included herein, eight were randomized controlled trials, three were retrospective intervention studies, two were case-control studies and one was a retrospective cohort study.

CONCLUSIONS

Today, the assessment of cleaning in environments can be evaluated by different methods, but there are advantages and disadvantages of these methods. Therefore, in the relevant literature, it is suggested that cleaning must be evaluated by several methods, not only one. Also, training the staff that carries out the cleaning and rewarding correct behavior by giving feedback are important approaches to increase the efficiency of cleaning. It is suggested that cleaning must be carried out every day, regularly with effective methods and equipment; frequency of cleaning during epidemics must be increased, institutions must prepare cleaning manuals according to evidence-based guidelines that are recognized at an international level.

Synergistic effects of antimicrobial peptide dendrimer-chitosan polymer conjugates against Pseudomonas aeruginosa

We report herein a new chemical platform for coupling chitosan derivatives to antimicrobial peptide dendrimers (AMPDs) with different degrees of ramification and molecular weights via thiol-maleimide reactions. Previous studies showed that simple incorporation of AMPDs to polymeric hydrogels resulted in a loss of antibacterial activity and augmented cytotoxicity to mammalian cells. We have shown that coupling AMPDs to chitosan derivatives enabled the two compounds to act synergistically. We showed that the antimicrobial activity was preserved when incorporating AMPD conjugates into various biopolymer formulations, including nanoparticles, gels, and foams. Investigating their mechanism of action using electron and time-lapse microscopy, we showed that the AMPD-chitosan conjugates were internalized after damaging outer and inner Gram-negative bacterial membranes. We also showed the absence of AMPD conjugates toxicity to mammalian cells. This chemical technological platform could be used for the development of new membrane disruptive therapeutics to eradicate pathogens present in acute and chronic wounds.

Occurrence of antibiotic resistance genes and multidrug-resistant bacteria during wastewater treatment processes

Wastewater treatment plants (WWTPs) constantly receive a wide variety of contaminants, including pharmaceuticals, and are potential reservoirs of antibiotic resistance genes (ARGs). This favors the development of multidrug-resistant bacteria (MRB) through horizontal gene transfer. Samples from five different WWTP processes were collected in September 2020 and January 2021 to monitor ARG resistomes and culturable MRB in the presence of eight different antibiotics. Nanopore-based ARG abundance and bacterial community analyses suggested that ARG accumulation favors the generation of MRB. Activated and mixed sludges tended to have lower bacterial diversity and ARG abundance because of selective forces that favored the growth of specific microorganisms during aeration processes. Escherichia strains enriched in WWTPs (up to 71%) were dominant in all the samples, whereas Cloacamonas species were highly abundant only in anaerobically digested sludge samples (60%-79%). Two ARG types [sulfonamide resistance genes (sul1) and aminoglycoside resistance genes (aadA1, aadA13, and aadA2)] were prevalent in all the processes. The total counts of culturable MRB, such as Niabella, Enterococcus, Bacillus, and Chryseobacterium species, gradually increased during aerobic WWTP processes. Genomic analyses of all MRB isolated from the samples revealed that the resistome of Enterococcus species harbored the highest number of ARGs (7-18 ARGs), commonly encoding ant(6)-la, lnu(B), erm(B), and tet(S/M). On the other hand, Niablella strains possibly had intrinsic resistant phenotypes without ARGs. All MRB possessed ARGs originating from the same mobile genetic elements, suggesting that WWTPs are hotspots for the migration of ARGs and emergence of MRB.

Analysis of risk factors for multidrug-resistant organisms in diabetic foot infection

BACKGROUND

To study the bacteriological characteristics, risk factors, and treatment of multi-drug resistance (MDR) organisms in patients with diabetic foot infection.

METHODS

Patients with diabetic foot ulcer admitted to hospital from June 2018 to December 2019 (n = 180) were selected as clinical subjects. Demographic information, routine blood test, wound culture and sensitivity were collected. Risk factors of MDR bacteria were analyzed.

RESULTS

Among 180 patients with diabetic foot ulcer, 146 were positive in bacterial culture, with 84 positive in MDR bacteria. A total of 182 strains were isolated, with 104 strains being multi-drug resistant. Body mass index, glycosylated hemoglobin, fasting blood glucose, triglyceride, course of ulcer, size of ulcer, peripheral neuropathy, peripheral vascular disease, osteomyelitis, peripheral blood leukocyte count, percentage of neutrophils, and previous use of antibiotics were the related factors of infection of MDR bacteria in diabetic foot ulcer patients (P < 0.05). The leukocyte count and neutrophil ratio of MDR-bacilli were lower than those of non MDR-bacilli (P < 0.05).

CONCLUSION

The risk of MDR bacteria in diabetic foot infection is high. It is necessary to evaluate the risk of multidrug-resistant bacteria by characterizing the course of disease, metabolic control, local ulcer and other aspects in order to formulate an effective treatment plan. The decrease of leukocyte count and neutrophil ratio may be related to damage of the host immune response.

Klebsiella-induced infections in domestic species: a case-series study in 697 animals (1997-2019)

Klebsiella species, particularly K. pneumoniae, are well-known opportunistic enterobacteria related to complexity of clinical infections in humans and animals, commonly refractory to conventional therapy. The domestic animals may represent a source of the pathogenic and multidrug-resistant Klebsiella species to humans. Nevertheless, most studies involving Klebsiella-induced infections in domestic animals are restricted to case reports or outbreaks. We retrospectively investigated selected epidemiological data, clinical aspects, and in vitro susceptibility pattern of 697 non-repetitive Klebsiella infections in livestock and companion species (1997-2019). The isolates were obtained from different clinical disorders from dogs (n = 393), cattle (n = 149), horses (n = 98), cats (n = 27), pigs (n = 22), sheep (n = 5), goats (n = 2), and buffalo (n = 1), except four isolates from subclinical bovine mastitis. Urinary (223/697 = 32%), enteric (117/697 = 16.8%), mammary (85/697 = 12.2%), reproductive (85/697 = 12.2%), and respiratory disorders (67/697 = 9.6%) were the most common clinical manifestations. Other miscellaneous clinical pictures (116/697 = 16.6%) included abscesses, otitis, hepatitis, conjunctivitis, pyodermitis, sepsis, and encephalitis. Norfloxacin (183/245 = 74.7%) and gentamicin (226/330 = 68.5%) were the most effective antimicrobials. High in vitro resistance of the isolates was seen to ampicillin (326/355 = 91.8%), amoxicillin/clavulanic acid (25/62 = 40.3%), and trimethoprim/sulfamethoxazole (100/252 = 39.7), and multidrug resistance to ≥ 3 classes of antimicrobials was found in 20.4% (142/697) isolates. Wide variety of clinical manifestations of Klebsiella-induced infections was observed, with a predominance of urinary, enteric, mammary, reproductive, and respiratory tract disorders, reinforcing opportunistic behavior of agent. Poor in vitro efficacy was observed to some conventional antimicrobials and ~ 20% of isolates exhibited resistance pattern, reinforcing the need for proper use of drugs on therapy approaches in domestic animals to avoid multidrug-resistant bacteria, an emergent global concern.

The role of the microbiota in the management of intensive care patients

The composition of the gut microbiota is highly dynamic and changes according to various conditions. The gut microbiota mainly includes difficult-to-cultivate anaerobic bacteria, hence knowledge about its composition has significantly arisen from culture-independent methods based on next-generation sequencing (NGS) such as 16S profiling and shotgun metagenomics. The gut microbiota of patients hospitalized in intensive care units (ICU) undergoes many alterations because of critical illness, antibiotics, and other ICU-specific medications. It is then characterized by lower richness and diversity, and dominated by opportunistic pathogens such as Clostridioides difficile and multidrug-resistant bacteria. These alterations are associated with an increased risk of infectious complications or death. Specifically, at the time of writing, it appears possible to identify distinct microbiota patterns associated with severity or infectivity in COVID-19 patients, paving the way for the potential use of dysbiosis markers to predict patient outcomes. Correcting the microbiota disturbances to avoid their consequences is now possible. Fecal microbiota transplantation is recommended in recurrent C. difficile infections and microbiota-protecting treatments such as antibiotic inactivators are currently being developed. The growing interest in the microbiota and microbiota-associated therapies suggests that the control of the dysbiosis could be a key factor in the management of critically ill patients. The present narrative review aims to provide a synthetic overview of microbiota, from healthy individuals to critically ill patients. After an introduction to the different techniques used for studying the microbiota, we review the determinants involved in the alteration of the microbiota in ICU patients and the latter's consequences. Last, we assess the means to prevent or correct microbiota alteration.

Advances in the development of antimicrobial peptides and proteins for inhaled therapy

Antimicrobial peptides and proteins (APPs) are becoming increasingly important in targeting multidrug-resistant (MDR) bacteria. APPs is a rapidly emerging area with novel molecules being produced and further optimised to enhance antimicrobial efficacy, while overcoming issues associated with biologics such as potential toxicity and low bioavailability resulting from short half-life. Inhalation delivery of these agents can be an effective treatment of respiratory infections owing to the high local drug concentration in the lungs with lower exposure to systemic circulation hence reducing systemic toxicity. This review describes the recent studies on inhaled APPs, including in vitro and in vivo antimicrobial activities, toxicity assessments, and formulation strategies whenever available. The review also includes studies on combination of APPs with other antimicrobial agents to achieve enhanced synergistic antimicrobial effect. Since different APPs have different biological and chemical stabilities, a targeted formulation strategy should be considered for developing stable and inhalable antimicrobial peptides and proteins. These strategies include the use of sodium chloride to reduce electrostatic interaction between APP and extracellular DNA in sputum, the use of D-enantiomers or dendrimers to minimise protease-mediated degradation and or the use of prodrugs to reduce toxicity. Although great effort has been put towards optimising the biological functions of APPs, studies assessing biological stability in inhalable aerosols are scarce, particularly for novel molecules. As such, formulation and manufacture of inhalable liquid and powder formulations of APPs are underexplored, yet they are crucial areas of research for clinical translation.

What is the role of Achromobacter species in patients with cystic fibrosis?

In recent years, advances in diagnosis and treatment have significantly modified the short- and long-term prognosis of cystic fibrosis (CF) patients. However, as in the past, the most important health problem that has significantly reduced the quality of life in CF patients is the progressive deterioration of lung structure and function. In recent years, Achromobacter species have emerged with increasing incidence in the respiratory secretions of CF subjects. The significance of this detection remains debated. In this review article, the characteristics of these pathogens, the importance of their presence in CF patients, and possible antibiotic treatment of treatments for colonization and infection are discussed. Literature analysis shows that Achromobacter species, mainly A. xylosoxidans, are pathogens with intrinsic characteristics that favour persistent lung colonization and several virulence factors and secretion systems that significantly interfere with respiratory cell survival. However, although it seems undebatable that Achromobacterspecies detection is a marker of CF severity, the role of these pathogens as a cause of lung structure and functional deterioration is not definitively established. Nonetheless, there is general agreement about the need for antibiotic therapy to eradicate these pathogens when they are detected in CF patients. Unfortunately, eradication is difficult, and no standard treatment is recommended by scientific societies. New possibilities are potentially offered by some recently developed drugs, such as cefiderocol, but further studies on the dosage, treatment duration and efficacy and safety of this new antibiotic in CF patients of different ages are urgently needed.

Infection microenvironment-related antibacterial nanotherapeutic strategies

The emergence and spread of antibiotic resistance is one of the biggest challenges in public health. There is an urgent need to discover novel agents against the occurrence of multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. The drug-resistant pathogens are able to grow and persist in infected sites, including biofilms, phagosomes, or phagolysosomes, which are more difficult to eradicate than planktonic ones and also foster the development of drug resistance. For years, various nano-antibacterial agents have been developed in the forms of antibiotic nanocarriers. Inorganic nanoparticles with intrinsic antibacterial activity and inert nanoparticles assisted by external stimuli, including heat, photon, magnetism, or sound, have also been discovered. Many of these strategies are designed to target the unique microenvironment of bacterial infections, which have shown potent antibacterial effects in vitro and in vivo. This review summarizes ongoing efforts on antibacterial nanotherapeutic strategies related to bacterial infection microenvironments, including targeted antibacterial therapy and responsive antibiotic delivery systems. Several grand challenges and future directions for the development and translation of effective nano-antibacterial agents are also discussed. The development of innovative nano-antibacterial agents could provide powerful weapons against drug-resistant bacteria in systemic or local bacterial infections in the foreseeable future.