Aerosolized Amikacin as Adjunctive Therapy of Ventilator-associated Pneumonia Caused by Multidrug-resistant Gram-negative Bacteria： A Single-center Randomized Controlled Trial

Background： Aerosolized amikacin （AA） is a current option for the management of ventilator-associated pneumonia （VAP） caused by multidrug-resistant Gram-negative bacteria （MDR-GNB）, as it is reported that AA could increase the alveolar level of the drug without increasing systemic toxicity. This study aimed to evaluate the efficacy and safety of AA as an adjunctive therapy for VAP caused by MDR-GNB. Methods： In this single-center, double-blind study conducted in a 36-bed general Intensive Care Unit （ICU） in a tertiary hospital from June 2014 to June 2016, 52 ICU patients with confirmed MDR-GNB VAP were randomized to two groups （AA group, n - 27 and placebo group, n = 25）. Amikacin （400 rag, q8h） or saline placebo （4 ml, q8h） was aerosolized for 7 days. The attending physician determined the administration of systemic antibiotics for VAP. Patients were tbllowed up for 28 days. Bacteriological eradication, clinical pulmonary infection score （CP1S）, and serum creatinine were assessed on day 7 of therapy. New resistance to amikacin, cure rate of VAP, weaning rate, and mortality were assessed on day 28. Results： The baseline characteristics of patients in both groups were similar. At the end of the treatment, 13 of the 32 initially detected bacterial isolates were eradicated in AA group, compared to 4 of 28 in placebo group （41% vs. 14%, P - 0.024）. As for patients, 11 of 27 patients treated with AA and 4 of 25 patients treated with placebo have eradication （41% vs. 16%, P = 0.049）. The adjunction of AA reduced CPIS （4.2 ± 1.6 vs. 5.8 ± 2.1, P = 0.007）. New drug resistance to amikacin and the change in serum creatinine were not detected in AA group. No significant differences in the clinical cure rate in survivors （48% vs. 35%, P = 0.444）, weaning rate （48% vs. 32%, P = 0.236）, and mortality （22% vs. 32%, P = 0.427） were detected between the two groups on day 28. Conclusions： As an adjunctive therapy of MDR-GNB VAP, AA successfully eradicated existing MDR organisms without inducing new resistance to amikacin or change in serum creatinine. However, the improvement of mortality was not found.

Low-Level Antibiotic Resistance among Staphylococcus aureus and Gram-Negative Pathogens from Infected Skin and Soft Tissues in Rural Kenya

Introduction: Bacterial skin and soft tissue infections (SSTIs) are a cause of frequent inpatient and outpatient care visits whose causative agents are associated with a high antimicrobial resistance burden. For insights on antimicrobial susceptibilities in a rural setting, we examined specimens from suspected SSTIs from two public health facilities in Kenya. We additionally assessed antibiotic use, appropriateness of empiric therapy and risk factors for SSTI. Methodology: Between 2021 and 2023, 265 patients at Kisii and Nyamira County Referral hospitals were enrolled. Wound swabs/aspirates were collected and processed following standard microbiological procedures. Identification and antimicrobial susceptibility were performed using the VITEK 2 Compact platform. Demographic, clinical, and microbiological data were analyzed with R Statistical software. Results: S. aureus was isolated in 16.2% (43/265) of patients with a methicillin resistance (MRSA) proportion of 14% (6/43). While 13/15 drugs elicited susceptibilities ranging from 84% - 100%, penicillin (16%) and trimethoprim-sulfamethoxazole [TMP-SXT] (23%) yielded the lowest susceptibilities. Escherichia coli (n = 33), Klebsiella pneumoniae (n = 8), Pseudomonas aeruginosa (n = 8), and Citrobacter species (n = 4) were the most commonly isolated gram-negative species. Gram-negative strains showed high susceptibilities to most of the tested drugs (71% - 100%) with the exception of ampicillin (18%), TMP-SXT (33%), and first and second generation cephalosporins. Conclusions: The low MRSA prevalence and generally high antibiotic susceptibilities for S. aureus and gram-negative bacteria present opportunities for antibiotic stewardship in the study setting. Diminished susceptibilities against penicillin/ampicillin and TMP-SXT accord with prevailing local data and add a layer of evidence for their cautious empiric use.

In vitro study on the transmission of multidrug-resistant bacteria from textiles to pig skin

BACKGROUND The survival of microorganisms on textiles and specifically on healthcare profes-sionals’(HCP)attire has been demonstrated in several studies.The ability of microorganisms to adhere and remain on textiles for up to hours or days raises questions as to their possible role in transmission from textile to skin via HCP to patients.AIM To evaluate the presence,survival and transmission of different multidrug-resistant bacteria(MDRB)from HCP attire onto skin.METHODS Three MDRB[methicillin-resistant Staphylococcus aureus(MRSA);vancomycin-resistant Enterococcus faecium(VRE);carbapenem-resistant Klebsiella pneumoniae,(CRKP)]were inoculated on textiles from scrubs(60%cotton-40%polyester)and white coat(100%cotton)at concentrations of 108 colony-forming units(CFU),105 CFU,and 103 CFU per mL.The inoculation of swatches was divided in time intervals of 1 min,5 min,15 min,30 min,1 h,2 h,3 h,4 h,5 h,and 6 h.At the end of each period,textiles were imprinted onto pig skins and each skin square was inverted onto three different selective chromogenic media.Growth from the pig skin squares was recorded for the 3 MDRB at the three above concentrations,for the whole length of the 6-h experiment.RESULTS MRSA was recovered from pig skins at all concentrations for the whole duration of the 6-h study.VRE was recovered from the concentration of 108 CFU/mL for 6 h and from 105 CFU/mL for up to 3 h,while showing no growth at 103 CFU/mL.CRKP was recovered from 108 CFU/mL for 6 h,up to 30 min from 105 CFU/mL and for 1 min from the concentration of 103 CFU/mL.CONCLUSION Evidence from the current study shows that MRSA can persist on textiles and transmit to skin for 6 h even at low concentrations.The fact that all MDRB can be sustained and transferred to skin even at lower concentrations,supports that textiles are implicated as vectors of bacterial spread.

A photoactivatable and phenylboronic acid-functionalized nanoassembly for combating multidrug-resistant gram-negative bacteria and their biofilms

Background:Multidrug-resistant(MDR)gram-negative bacteria-related infectious diseases have caused an increase in the public health burden and mortality.Moreover,the formation of biofilms makes these bacteria difficult to control.Therefore,developing novel interventions to combat MDR gram-negative bacteria and their biofilms-related infections are urgently needed.The purpose of this study was to develop a multifunctional nanoassembly(IRNB)based on IR-780 and N,N-di-sec-butyl-N,N-dinitroso-1,4-phenylenediamine(BNN6)for synergistic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria.Methods:The characterization and bacteria-targeting ability of IRNB were investigated.The bac-tericidal efficacy of IRNB against gram-negative bacteria and their biofilms was demonstrated by crystal violet staining assay,plate counting method and live/dead staining in vitro.The antibacterial efficiency of IRNB was examined on a subcutaneous abscess and cutaneous infected wound model in vivo.A cell counting kit-8 assay,Calcein/PI cytotoxicity assay,hemolysis assay and intravenous injection assay were performed to detect the biocompatibility of IRNB in vitro and in vivo.Results:Herein,we successfully developed a multifunctional nanoassembly IRNB based on IR-780 and BNN6 for synergistic photothermal therapy(PTT),photodynamic therapy(PDT)and nitric oxide(NO)effect triggered by an 808 nm laser.This nanoassembly could accumulate specifically at the infected sites of MDR gram-negative bacteria and their biofilms via the covalent coupling effect.Upon irradiation with an 808 nm laser,IRNB was activated and produced both reactive oxygen species(ROS)and hyperthermia.The local hyperthermia could induce NO generation,which further reacted with ROS to generate ONOO−,leading to the enhancement of bactericidal efficacy.Furthermore,NO and ONOO−could disrupt the cell membrane,which converts bacteria to an extremely susceptible state and further enhances the photothermal effect.In this study,IRNB showed a superior photothermal-photodynamic-chemo(NO)synergistic therapeutic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria.This resulted in effective control of associated infections,relief of inflammation,promotion of re-epithelization and collagen deposition,and regulation of angiogenesis during wound healing.Moreover,IRNB exhibited excellent biocompatibility,both in vitro and in vivo.Conclusions:The present research suggests that IRNB can be considered a promising alternative for treating infections caused by MDR gram-negative bacteria and their biofilms.

High mortality associated with gram-negative bacterial bloodstream infection in liver transplant recipients undergoing immunosuppression reduction

BACKGROUND Immunosuppression is an important factor in the incidence of infections in transplant recipient.Few studies are available on the management of immunosuppression(IS)treatment in the liver transplant(LT)recipients complicated with infection.The aim of this study is to describe our experience in the management of IS treatment during bacterial bloodstream infection(BSI)in LT recipients and assess the effect of temporary IS withdrawal on 30 d mortality of recipients presenting with severe infection.AIM To assess the effect of temporary IS withdrawal on 30 d mortality of LT recipients presenting with severe infection.METHODS A retrospective study was conducted with patients diagnosed with BSI after LT in the Department of Liver Surgery,Renji Hospital from January 1,2016 through December 31,2017.All recipients diagnosed with BSI after LT were included.Univariate and multivariate Cox regression analysis of risk factors for 30 d mortality was conducted in the LT recipients with Gram-negative bacterial(GNB)infection.RESULTS Seventy-four episodes of BSI were identified in 70 LT recipients,including 45 episodes of Gram-positive bacterial(GPB)infections in 42 patients and 29 episodes of GNB infections in 28 patients.Overall,IS reduction(at least 50%dose reduction or cessation of one or more immunosuppressive agent)was made in 28(41.2%)cases,specifically,in 5(11.9%)cases with GPB infections and 23(82.1%)cases with GNB infections.The 180 d all-cause mortality rate was 18.5%(13/70).The mortality rate in GNB group(39.3%,11/28)was significantly higher than that in GPB group(4.8%,2/42)(P=0.001).All the deaths in GNB group were attributed to worsening infection secondary to IS withdrawal,but the deaths in GPB group were all due to graft-versus-host disease.GNB group was associated with significantly higher incidence of intra-abdominal infection,IS reduction,and complete IS withdrawal than GPB group(P<0.05).Cox regression showed that rejection(adjusted hazard ratio 7.021,P=0.001)and complete IS withdrawal(adjusted hazard ratio 12.65,P=0.019)were independent risk factors for 30 d mortality in patients with GNB infections after LT.CONCLUSION IS reduction is more frequently associated with GNB infection than GPB infection in LT recipients.Complete IS withdrawal should be cautious due to increased risk of mortality in LT recipients complicated with BSI.

Seafood as a Reservoir of Gram-negative Bacteria Carrying Integrons and Antimicrobial Resistance Genes in Japan

PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim

Impact of Polymyxin Resistance on Virulence and Fitness among Clinically Important Gram-Negative Bacteria

Humanity is facing an enormous and growing worldwide threat from the emergence of multi-drug-resistant(MDR)Gram-negative bacteria such as Escherichia coli,Klebsiella pneumoniae,and Acinetobacter baumannii.Polymyxin B and E(colistin)constitute the last-line therapies for treating MDR Gram-negative bacteria.Polymyxin is a cationic antibacterial peptide that can destroy the outer membrane of Gram-negative bacteria.With the increasing clinical application of polymyxin,however,there have been many reports of the occurrence of polymyxin-resistant Gram-negative bacteria.This resistance is mainly mediated by the modification or complete loss of lipopolysaccharide(LPS).LPS is also a virulence factor of Gram-negative bacteria,and alterations of LPS may correlate with virulence.Although it is generally believed that the biological costs associated with drug resistance may enable benign susceptible bacteria to overcome resistant bacteria when antibiotic pressure is reduced,some studies have shown that polymyxin-resistant bacteria are associated with higher virulence and greater fitness compared with their susceptible counterparts.To predict the development of polymyxin resis-tance and evaluate interventions for its mitigation,it is important to understand the relative biological cost of polymyxin resistance compared with susceptibility.The impact of polymyxin resistance mecha-nisms on the virulence and fitness of these three Gram-negative bacteria are summarized in this review.

An Improved Approach for Rapidly Identifying Different Types of Gram-Negative Bacterial Secreted Proteins

Protein secretion plays an important role in bacterial lifestyles. In Gram-negative bacteria, a wide range of proteins are secreted to modulate the interactions of bacteria with their environments and other bacteria via various secretion systems. These proteins are essential for the virulence of bacteria, so it is crucial to study them for the pathogenesis of diseases and the development of drugs. Using amino acid composition (AAC), position-specific scoring matrix (PSSM) and N-terminal signal peptides, two different substitution models are firstly constructed to transform protein sequences into numerical vectors. Then, based on support vector machine (SVM) and the “one to one”?algorithm, a hybrid multi-classifier named SecretP v.2.2 is proposed to rapidly and accurately?distinguish different types of Gram-negative?bacterial secreted proteins. When performed on the same test set for a comparison with other methods, SecretP v.2.2 gets the highest total sensitivity of 93.60%. A public independent dataset is used to further test the power of SecretP v.2.2 for predicting NCSPs, it also yields satisfactory results.

Antibacterial activities of ethanol extracts of Philippine medicinal plants against multidrug-resistant bacteria

Objective: To investigate the antibacterial activities of crude ethanol extracts of 12 Philippine medicinal plants.Methods: Crude ethanol extracts from 12 Philippine medicinal plants were evaluated for their antibacterial activity against methicillin-resistant Staphylococcus aureus, vancomycinresistant Enterococcus, extended spectrum β-lactamase-producing, carbapenem-resistant Enterobacteriaceae and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii. Results: The leaf extracts of Psidium guajava, Phyllanthus niruri, Ehretia microphylla and Piper betle(P. betle) showed antibacterial activity against the Gram-positive methicillinresistant Staphylococcus aureus and vancomycin-resistant Enterococcus. P. betle showed the highest antibacterial activity for these bacteria in the disk diffusion(16-33 mm inhibition diameter), minimum inhibitory concentration(19-156 μg/m L) and minimum bactericidal concentration(312 μg/m L) assays. P. betle leaf extracts only showed remarkable antibacterial activity for all the Gram-negative multidrug-resistant bacteria(extended spectrum β-lactamaseproducing, carbapenem-resistant Enterobacteriaceae and metallo-β-lactamase-producing) in the disk diffusion(17-21 mm inhibition diameter), minimum inhibitory concentration(312-625 μg/m L) and minimum bactericidal concentration(312-625 μg/m L) assays. Conclusions: P. betle had the greatest potential value against both Gram-negative and Grampositive multidrug-resistant bacteria. Favorable antagonistic activities were also exhibited by the ethanol extracts of Psidium guajava, Phyllanthus niruri and Ehretia microphylla.

Epidemiological Characteristics, Resistance Patterns and Spread of Gram-Negative Bacteria Related to Colonization of Patients in Intensive Care Units

Our aim was to determine the epidemiological characteristics, the resistance patterns and the spread of Gram negative bacteria related to colonization of patients in adult Intensive Care Units. Methods: A prospective cohort of patients colonized and/or infected with Gram negative bacteria was conducted at two adult ICUs from hospitals in Brazil (April 2012 to February 2013). Nasal, groin and perineum swabs were performed. Samples were incubated on MacConkey and cetrimide agar (48 h at 37℃) and identification tests (Vitek-BioMérieux), antibiogram (Bauer-Kirby method), Carba NP test, Polymerase Chain Reaction (PCR) and sequencing were performed. The patterns of resistant microorganisms were compared by rep-PCR (Diversilab). Results: There were 53 cases of colonization. In these cases, we identified imipenem-resistant Acinetobacter baumannii (51%), Pseudomonas aeruginosa (32%), Klebsiella pneumoniae ESBL (38%) or imipenem resistant (5.6%). The use of antimicrobials and medical devices were related to colonization (p The resistance patterns expressed by Klebsiella pneumoniae were ESBL (CTX-M, SHV e TEM) and KPC2. A verified profile of Acinetobacter baumannii was related to OXA-23 and OXA-253 (OXA-143 variant). The profiles ESBL and KPC2 expressed by Klebsiella pneumoniae were distributed between the both ICUs. The distribution of OXA-23 and OXA-253 was verified only in one ICU. The similarity of strains ranged from 80% to 95%, highlighting the horizontal transference of these microorganisms.

Prevalence and Antimicrobial Resistance of Gram-Negative Bacteria Isolates in Shellfish Samples from Two River Estuaries in South-South Nigeria

Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the antibiotic resistance patterns of Gram-negative bacteria from shellfish. We analyzed a total of 540 shellfish (117 clams, 88 oysters, and 136 periwinkles) samples collected from different vendors at Iko and Douglas Creeks in Akwa Ibom State, South-South Nigeria. Conventional cultural techniques, morphological, biochemical characteristics, and PCR amplification were used to identify the bacterial isolates. Antibiotic susceptibility tests (Kirby-Bauer disk diffusion method) and ESBL phenotype (disk) of the isolates were performed. One hundred and thirty-five (135) Gram-negative bacteria comprising 5 genera and 14 species were detected at a prevalence of: Alcaligenes faecalis TRB-7 38 (28.2%), Pseudomonas oryzihabitans strain KCB005 16 (11.9%), Paenalcaligenes retgerii strain B5 12 (8.9%) Pseudomonas aeruginosa JB2 10 (7.4%), Providencia stuartii DMC-28b 9 (6.7%), Alcaligenes species TLT151 8 (5.9%), Pseudomonas aeruginosa CIFRI DTSB1 7 (5.2%), Paenalcaligenes species UN24 7 (5.2%), Alcaligenes faecalis BT10 7 (5.2%), Vibrio species strain PrVy108 6 (4.4%), Pseudomonas xiamenensis C10-2 5 (3.7%), Providencia vemicola Bu15_38 4 (2.9%), Pseudomonas anguillisceptica 4029 3 (2.2%), and Pseudomonas aeruginosa N15-01092 3 (2.2%). All tested isolates showed various degrees of resistance to the thirteen antimicrobials evaluated. High levels of resistance (100%) to cefepime and imipenem were expressed by all isolates except the Providencia species. For the EBSL indicators, all isolates apart from Alcaligenes species were resistant (100%) to ceftriaxone. All Vibrio species were susceptible to norfloxacin, nalidixic acid, and ceftazidime. The identification of antibiotic resistant Gram-negative bacteria (GNARB) from shellfish in this study highlights the risk of disseminated multi-drug resistance—a serious public health concern.

Comparison of the serum contents of inflammatory mediators and oxidative stress mediators between patients with gram-positive bacteria and gram-negative bacteria infection

Objective: To compare the serum contents of inflammatory mediators and oxidative stress mediators between patients with gram-positive bacteria and gram-negative bacteria infection. Methods: Patients who were diagnosed with bloodstream bacterial infection in Zigong Third People's Hospital between March 2015 and April 2017 were selected as the research subjects and divided into gram-positive group and gram-negative group according to the results of blood culture and strain identification, and serum levels of inflammatory mediators PCT, IL-1β, IL-6, sTREM-1, TNF-α, NGAL, SAA, HPT and hs-CRP as well as oxidative stress mediators MDA, AOPP, TAC, CAT and SOD were determined. Results: Serum PCT, IL-1β, IL-6, sTREM-1, TNF-α, NGAL, SAA, HPT, hs-CRP, MDA and AOPP levels of gram-negative group were greatly higher than those of gram-positive group while TAC, CAT and SOD levels were greatly lower than those of gram-positive group. Conclusion: The changes of inflammatory mediators and oxidative stress mediators in the serum of patients with gram-negative bacteria infection are more significant than those of patients with gram-positive bacteria infection.

Analysis and control of multidrug-resistant bacteria in hospital

Objective:To investigate the status of multidrug-resistant bacteria and the prevention and control measures of nosocomial in-fection in our hospital.Methods:The annual monitoring of multidrug-resistant bacteria infection was measured to summarize the bacteria species,statistical distribution and antibiotic resistance.Identification of multidrug-resistant bacteria infection in patients infected or hospital acquired infections was taken to analyze the reasons of multidrug-resistant bacteria strain and put forward the relevant measures.Results:The top five of multidrug-resistant strains infections were:Gram-positive bacteria including methicillin-resistant Staphylococcus aureus,Staphylococcus aureus;Gram-negative bacteria including Escherichia coli,Acinetobacter bauman-nii,Klebsiella pneumoniae.Conclusions:The occurrence of multidrug-resistant hospital infections could be prevented by rational use of antibiotics,hand hygiene and disinfection management,and reinforced monitoring of multidrug-resistant bacteria.

De novo design of highly efficient type-Ⅰphotosensitizer based onπ-conjugated oligomer for photodynamic eradication of multidrug-resistant bacterial infections

Traditional photosensitizers show limited singlet oxygen generation in hypoxic infection lesions,which greatly suppress their performance in antibacterial therapy.Meanwhile,there still is lack of feasible design strategy for developing hypoxia-overcoming photosensitizers agents.Herein,radical generation ofπ-conjugated small molecules is efficiently manipulated by an individual selenium(Se)substituent.With this strategy,the first proof-of-concept study of a Se-anchored oligo(thienyl ethynylene)(OT-Se)with high-performance superoxide radical(O_(2)^(·-))and hydroxyl radical(·OH)generation capability is present,and achieves efficient antibacterial activities towards the clinically extracted multidrug-resistant bacteria methicillin-resistant S.aureus(MRSA)and carbapenem-resistant E.coli(CREC)at sub-micromolar concentration under a low white light irradiation(30 mW/cm^(2)).The water-dispersible OT-Se shows a good bacteria-anchoring capability,biocompatibility,and complete elimination of multidrug-resistant bacteria wound infection in vivo.This work offers a strategy to boost type-I photodynamic therapy(PDT)performance for efficient antibacterial treatments,advancing the development of antibacterial agents.

Risk factors and mortality rates of carbapenem-resistant Gram-negative bacterial infections in intensive care units

Background The prevalence of hospital-acquired infections caused by carbapenem-resistant gram-negative bacteria(CRGNB)is increasing worldwide.Several risk factors have been associated with such infections.The present study aimed to identify risk factors and determine the mortality rates associated with CRGNB infections in intensive care units.Methods This retrospective case-control study was conducted at Erciyes University Hospital(Kayseri,Turkey)between January 2017 and December 2021.Demographic and laboratory data were obtained from the Infection Control Committee data and record system.Patients who had CRGNB infection 48–72 h after hospitalization were assigned to the case group,while those who were not infected with CRGNB during hospitalization formed the control group.Risk factors,comorbidity,demographic data,and mortality rates were compared between the two groups.Results Approximately 1449 patients(8.97%)were monitored during the active follow-up period;of those,1171 patients were included in this analysis.CRGNB infection developed in 14 patients(70.00%)who had CRGNB colonization at admission;in 162(78.26%)were colonized during hospitalization,whereas 515(54.56%)were not colonized.There was no significant difference in age,sex(male/female)or comorbidities.The total length of hospital stay was statistically significantly longer(P=0.001)in the case group(median:24[interquartile range:3–378]days)than the control group(median:16[interquartile range:3–135]days).The rates of colonization at admission(25.5%;vs.10.6%,P=0.001)and mortality(64.4%vs.45.8%,P=0.001)were also significantly higher in the cases than in the control group,respectively.In the univariate analysis,prolonged hospitalization,the time from intensive care unit admission to the development of infection,presence of CRGNB colonization at admission,transfer from other hospitals,previous antibiotic use,enteral nutrition,transfusion,hemodialysis,mechanical ventilation,tracheostomy,reintubation,central venous catheter,arterial catheterization,chest tube,total parenteral nutrition,nasogastric tube use,and bronchoscopy procedures were significantly associated with CRGNB infections(P<0.05).Multivariate analysis identified the total length of stay in the hospital(odds ratio[OR]=1.02;95%confidence interval[CI]:1.01 to 1.03;P=0.001),colonization(OR=2.19;95%CI:1.53 to 3.13;P=0.001),previous antibiotic use(OR=2.36;95%CI:1.53 to 3.62;P=0.001),intubation(OR=1.59;95%CI:1.14 to 2.20;P=0.006),tracheostomy(OR=1.42;95%CI:1.01 to 1.99;P=0.047),and central venous catheter use(OR=1.62;95%CI:1.20 to 2.19;P=0.002)as the most important risk factors for CRGNB infection.Conclusions Colonization,previous use of antibiotics,and invasive interventions were recognized as the most important risk factors for infections.Future research should focus on measures for the control of these parameters.

Immunogenomics for identification of disease resistance genes in pigs: a review focusing on Gram-negative bacilli

Over the past years, infectious disease has caused enormous economic loss in pig industry. Among the pathogens, gram negative bacteria not only cause inflammation, but also cause different diseases and make the pigs more susceptible to virus infection. Vaccination, medication and elimination of sick pigs are major strategies of controlling disease. Genetic methods, such as selection of disease resistance in the pig, have not been widely used. Recently, the completion of the porcine whole genome sequencing has provided powerful tools to identify the genome regions that harboring genes controlling disease or immunity. Immunogenornics, which combines DNA variations, transcriptorne, immune response, and QTL mapping data to illustrate the interactions between pathogen and host immune system, will be an effective genomics tool for identification of disease resistance genes in pigs. These genes will be potential targets for disease resistance in breeding programs. This paper reviewed the progress of disease resistance study in the pig focusing on Gram-negative bacilli. Major porcine Gram-negative bacilli and diseases, suggested candidate genes/pathways against porcine Gram-negative bacilli, and distributions of QTLs for immune capacity on pig chromosomes were summarized. Some tools for immunogenomics research were described. We conclude that integration of sequencing, whole genome associations, functional genomics studies, and immune response information is necessary to illustrate molecular mechanisms and key genes in disease resistance.

Control of multidrug-resistant planktonic Acinetobacter baumannii:biocidal efficacy study by atmospheric-pressure air plasma

In this research,an atmospheric-pressure air plasma is used to inactivate the multidrug-resistant Acinetobacter baumannii in liquid.The efficacy of the air plasma on bacterial deactivation and the cytobiological variations after the plasma treatment are investigated.According to colony forming units,nearly all the bacteria（6-log） are inactivated after 10 min of air plasma treatment.However,7% of the bacteria enter a viable but non-culturable state detected by the resazurin based assay during the same period of plasma exposure.Meanwhile,86% of the bacteria lose their membrane integrity in the light of SYTO 9/PI staining assay.The morphological changes in the cells are examined by scanning electron microscopy and bacteria with morphological changes are rare after plasma exposure in the liquid.The concentrations of the long-living RS,such as H2O2,NO3^- and O3,in liquid induced by plasma treatment are measured,and they increase with plasma treatment time.The changes of the intracellular ROS may be related to cell death,which may be attributed to oxidative stress and other damage effects induced by RS plasma generated in liquid.The rapid and effective bacteria inactivation may stem from the RS in the liquid generated by plasma and air plasmas may become a valuable therapy in the treatment of infected wounds.

Detection of the Production of Klebsiella Pneumoniae Carbapenemase, New Delhi Metallo-Beta-Lactamase and Oxacillinase-48-Type Carbapenemases by Gram-Negative Bacilli in Resource-Limited Setting

Background: The increasing resistance of bacteria to various antibiotics is a worldwide public health issue. Carbapenems that have elicited great hope in treating infections caused by multidrug-resistant germs have seen their efficacy narrowed over time with the emergence of other novel resistance mechanisms, notably the production of Carbapenemases. Methods: A prospective cross-sectional study was conducted from May 2017 to May 2018 in Douala (Cameroon) to detect carbapenemase-producing Gram-negative bacilli. Isolated strains were identified using the Vitek2TM system. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method on agar plates with 20 selected commercially available antibiotic discs. The bacterial strains were tested for the production of three Carbapenemases (OXA-48, NDM, KPC), using an immuno-chromatographic technique, with the “RESIST-3 O.K.N. K-SeT” rapid detection kit. Results: During the study period, 1687 strains of Gram-negative bacilli were isolated in selected laboratories with a total of 200 multi-resistant strains identified (11.9%). Among the multi-resistant strains, E. coli was the species most represented in Enterobacteriaceae (27.5%) followed by K. pneumoniae (15.5%) and the non-fermenting Gram-negative bacilli were predominantly P. aeruginosa (20.5%). These strains mainly came from urine and pus, i.e. 41% and 32% respectively. Thirty-two (16%) strains produced one of the Carbapenemases with a higher frequency at the General Hospital (84%). NDM-type carbapenemase was the most frequently identified (8.5%), OXA-48 type 7.5%, and no KPC production was observed. Among the Enterobacteriaceae 22.9% produced Carbapenemases and only 5.1% of the non-fermenting bacilli produced these enzymes. The isolates strains were completely resistant to all antibiotics except Amikacin and Fosfomycin. The strains producing the NDM-type carbapenemase showed higher rates of resistance to almost all of the antibiotics tested. Conclusion: Multidrug-resistant strains are experiencing an increase in evolution. The apparition of strains producing Carbapenemases prominently, the NDM and OXA-48 favor this increase. The activities of antibiotics with high efficacies on these strains are low.

A nanoplatform with oxygen self-supplying and heat-sensitizing capabilities enhances the efficacy of photodynamic therapy in eradicating multidrug-resistant biofilms

Bacterial biofilms,especially those caused by multidrug-resistant bacteria,have emerged as one of the greatest dangers to global public health.The acceleration of antimicrobial resistance to conventional an-tibiotics and the severe lack of new drugs necessitates the development of novel agents for biofilm eradication.Photodynamic therapy(PDT)is a promising non-antibiotic method for treating bacterial infections.However,its application in biofilm eradication is hampered by the hypoxic microenvironment of biofilms and the physical protection of extracellular polymeric substances.In this study,we develop a composite nanoplatform with oxygen(O_(2))self-supplying and heat-sensitizing capabilities to improve the PDT efficacy against biofilms.CaO_(2)/ICG@PDA nanoparticles(CIP NPs)are fabricated by combining calcium peroxide(CaO_(2))with the photosensitizer indocyanine green(ICG)via electrostatic interactions,followed by coating with polydopamine(PDA).The CIP NPs can gradually generate O_(2)in response to the acidic microenvironment of the biofilm,thereby alleviating its hypoxic state.Under near-infrared(NIR)irradiation,the nanoplatform converts O_(2)into a significant amount of singlet oxygen(^(1)O_(2))and heat to eradicate biofilm.The generated heat enhances the release of O_(2),accelerates the generation of^(1)O_(2)in PDT,increases cell membrane permeability,and increases bacterial sensitivity to^(1)O_(2).This nanoplatform significantly improves the efficacy of PDT in eradicating biofilm-dwelling bacteria without fostering drug resistance.Experiments on biofilm eradication demonstrate that this nanoplatform can eradicate over 99.9999%of methicillin-resistant Staphylococcus aureus(MRSA)biofilms under 5-min NIR irradiation.Notably,these integrated advantages enable the system to promote the healing of MRSA biofilm-infected wounds with negligible toxicity in vivo,indicating great promise for overcoming the obstacles associated with bacterial biofilm eradication.

Evolution and development of potent monobactam sulfonate candidate IMBZ18g as a dual inhibitor against MDR Gram-negative bacteria producing ESBLs

A series of new monobactam sulfonates is continuously synthesized and evaluated for their antimicrobial efficacies against Gram-negative bacteria.Compound 33a(IMBZ18G)is highly effective in vitro and in vivo against clinically intractable multi-drug-resistant(MDR)Gram-negative strains,with a highly druglike nature.The checkerboard assay reveals its significant synergistic effect withβ-lactamase inhibitor avibactam,and the MIC values against MDR enterobacteria were reduced up to 4—512folds.X-ray co-crystal and chemoproteomic assays indicate that the anti-MDR bacteria effect of 33a results from the dual inhibition of the common PBP3 and some class A and Cβ-lactamases.Accordingly,preclinical studies of 33a alone and 33a-avibactam combination as potential innovative candidates are actively going on,in the treatment ofβ-lactamase-producing MDR Gram-negative bacterial infections.