Microglia in Ischemic Stroke: Pathogenesis Insights and Therapeutic Challenges.

Ischemic stroke is the most common type of stroke, which is the main cause of death and disability on a global scale. As the primary immune cells in the brain that are crucial for preserving homeostasis of the central nervous system microenvironment, microglia have been found to exhibit dual or even multiple effects at different stages of ischemic stroke. The anti-inflammatory polarization of microglia and release of neurotrophic factors may provide benefits by promoting neurological recovery at the lesion in the early phase after ischemic stroke. However, the pro-inflammatory polarization of microglia and secretion of inflammatory factors in the later phase of injury may exacerbate the ischemic lesion, suggesting the therapeutic potential of modulating the balance of microglial polarization to predispose them to anti-inflammatory transformation in ischemic stroke. Microglia-mediated signaling crosstalk with other cells may also be key to improving functional outcomes following ischemic stroke. Thus, this review provides an overview of microglial functions and responses under physiological and ischemic stroke conditions, including microglial activation, polarization, and interactions with other cells. We focus on approaches that promote anti-inflammatory polarization of microglia, inhibit microglial activation, and enhance beneficial cell-to-cell interactions. These targets may hold promise for the creation of innovative therapeutic strategies.

Advancing Understanding of Childhood Asthma: Lessons Learned from Birth Cohort Studies.

Asthma and allergies are some of the most common chronic disorders affecting children, the prevalence of which has been increasing in countries and regions undergoing rapid development like China. To curb the rising tide of allergies and safeguard the health of future generations, it is of critical importance to understand how asthma inception is influenced by factors acting at different life stages. Birth cohorts represent a powerful tool to investigate the temporal sequence of exposures along the natural course of asthma. We examined recent evidence on birth cohort studies of asthma and allergic diseases and evaluated their strengths and weaknesses. Essential elements for a successful birth cohort are proposed to further elucidate asthma etiology and pathogenies. Initiating new cohorts in understudied populations with the application of advanced analytical approaches will be needed. Moreover, fostering collaborative networks using standardized methodologies should be prioritized to enable integration of findings across diverse cohorts. There remains an urgent and unmet need to further translate the seminal findings from asthma birth cohort studies into targeted primary prevention strategies to eradicate the disease.

Antibacterial Activity of Surfactin and Synergistic Effect with Conventional Antibiotics Against Methicillin-Resistant Staphylococcus aureus Isolated from Patients with Diabetic Foot Ulcers.

Introduction: The prevalence of diabetic foot ulcers (DFUs) is increasing, leading to a huge financial burden and human suffering. Furthermore, antibiotic resistance is an urgent problem in the realm of clinical practice. Antimicrobial peptides are an effective and feasible strategy for combating infections caused by drug-resistant bacteria. Therefore, we investigated the in vitro antimicrobial ability of the lipopeptide surfactin, either alone or in combination with conventional antibiotics, against the standard and clinical strains of Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), isolated from patients with DFUs. Methods: The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of surfactin on the selected strains were evaluated by a microbroth dilution technique. The growth curves of the selected strains with and without surfactin were measured, and transmission electron microscopy was used to observe the structure of surfactin-treated bacterial cells. The biofilm inhibitory abilities of surfactin were assessed by crystal violet staining. The antimicrobial interactions between surfactin and conventional antibiotics were established using a checkerboard assay, as well as determining the mutant prevention concentration. The inhibitory effect of surfactin on penicillinase was tested by iodometry. Results: The MIC and MBC values of surfactin ranged from 512 to 1024 µg/mL and 1024 to 2048 µg/mL, respectively. Moreover, surfactin significantly prevented the S. aureus biofilm formation and displayed limited toxicity on human red blood cells. The synergies between surfactin and ampicillin, oxacillin, and tetracycline against S. aureus were revealed. In vitro resistance was not readily produced by surfactin. The action of surfactin may be by disrupting bacterial cell membranes and inhibiting penicillinase. Conclusion: Surfactin appears to be a potential option for the treatment of DFUs infected with MRSA, as it is capable of improving antimicrobial activities and can be used alone or in combination with conventional antibiotics to prevent or postpone the emergence of resistance.

Risk Factors, Outcomes, and Predictions of Extensively Drug-Resistant Acinetobacter baumannii Nosocomial Infections in Patients with Nervous System Diseases.

Purpose: Acinetobacter baumannii has evolved to become a major pathogen of nosocomial infections, resulting in increased morbidity and mortality. This study aimed to investigate the risk factors, outcomes, and predictions of extensively drug-resistant (XDR)-A. baumannii nosocomial infections in patients with nervous system diseases (NSDs). Methods: A retrospective study of patients infected with XDR-A. baumannii admitted to the Affiliated Hospital of Southwest Medical University (Luzhou, China) from January 2021 to December 2022 was conducted. Three multivariate regression models were used to assess the risk factors and predictive value for specific diagnostic and prognostic subgroups. Results: A total of 190 patients were included, of which 84 were diagnosed with NSDs and 80% of those were due to stroke. The overall rates of all-cause mortality for XDR-A. baumannii nosocomial infections and those in NSDs were 38.9% and 40.5%, respectively. Firstly, hypertension, indwelling gastric tube, tracheotomy, deep puncture, bladder irrigation, and pulmonary infections were independent risk factors for XDR-A. baumannii nosocomial infections in patients with NSDs. Moreover, pulmonary infections, the aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio, and the neutrophil-to-lymphocyte ratio (NLR) were significantly associated with increased mortality rates in patients with nosocomial infections caused by XDR-A. baumannii. Thirdly, NLR and cardiovascular diseases accounted for a high risk of mortality for XDR-A. baumannii nosocomial infections in patients with NSDs. The area under the curves of results from each multivariate regression model were 0.827, 0.811, and 0.853, respectively. Conclusion: This study reveals the risk factors of XDR-A. baumannii nosocomial infections in patients with NSDs, and proves their reliable predictive value. Early recognition of patients at high risk, sterilizing medical tools, and regular blood monitoring are all critical aspects for minimizing the nosocomial spread and mortality of A. baumannii infections.

Antibiotic susceptibility pattern, risk factors, and prediction of carbapenem-resistant Pseudomonas aeruginosa in patients with nosocomial pneumonia.

Objectives: This study was aimed at describing antibiotic susceptibility patterns and developing a predictive model by assessing risk factors for carbapenem-resistant Pseudomonas aeruginosa (CRPA). Methods: A retrospective case-control study was conducted at a teaching hospital in China from May 2019 to July 2021. Patients were divided into the carbapenem-susceptible P. aeruginosa (CSPA) group and the CRPA group. Medical records were reviewed to find an antibiotic susceptibility pattern. Multivariate analysis results were used to identify risk factors and build a predictive model. Results: A total of 61 among 292 patients with nosocomial pneumonia were infected with CRPA. In the CSPA and CRPA groups, amikacin was identified as the most effective antibiotic, with susceptibility of 89.7%. The CRPA group showed considerably higher rates of resistance to the tested antibiotics. Based on the results of mCIM and eCIM, 28 (45.9%) of 61 isolates might be carbapenemase producers. Independent risk factors related to CRPA nosocomial pneumonia were craniocerebral injury, pulmonary fungus infection, prior use of carbapenems, prior use of cefoperazone-sulbactam, and time at risk (≥15 d). In the predictive model, a score >1 point indicated the best predictive ability. Conclusions: CRPA nosocomial pneumonia could be predicted by risk factor assessment particularly based on the underlying disease, antimicrobial exposure, and time at risk, which could help prevent nosocomial pneumonia.

Cigarette Smoking and Peripheral Vascular Disease are Associated with Increasing Risk of ESKAPE Pathogen Infection in Diabetic Foot Ulcers.

Objective: Diabetic foot ulcers (DFUs) and ESKAPE pathogens have attracted attention globally, but the role of ESKAPE pathogens in diabetic foot infection is not well described. The purpose of this study was to evaluate the clinical features, antimicrobial resistance, and risk factors for ESKAPE infection in patients with DFUs. Methods: A retrospective study was conducted on 180 patients with diabetic foot infection admitted to The Affiliated Hospital of Southwest Medical University (Luzhou, China), from January 2017 to April 2021. Antimicrobial susceptibilities of all isolates were determined. Multivariate logistic regression analysis was performed to analyze the independent risk factors for ESKAPE infection, multidrug-resistant (MDR)-ESKAPE infection, MDR-pathogen infection, and severe group in patients with DFUs. Results: A total of 206 isolates were collected, of which 42.2% were ESKAPE pathogens. The independent risk factors for ESKAPE infection were cigarette smoking (OR = 1.958; 95% CI, 1.015-3.777) and peripheral vascular disease (OR = 2.096; 95% CI, 1.100-3.992), while alcohol consumption (OR = 2.172; 95% CI, 1.104-4.272) was the independent risk factor for MDR-pathogen infection. Additionally, the independent risk factors for severe DFU group were invasive treatment (OR = 326.642; 95% CI, 76.644-1392.08), the duration of systemic antibiotic treatment (OR = 0.918; 95% CI, 0.849-0.992), and length of hospital stay (OR = 1.145; 95% CI, 1.043-1.256). No independent risk factors for MDR-ESKAPE infection were found. Conclusion: Our data established the microbiological features of ESKAPE pathogens and clinical manifestations of diabetic foot infection, and provide support for monitoring and management of ESKAPE infection in patients with DFUs in southwest China.

An outbreak of extensively drug-resistant and hypervirulent Klebsiella pneumoniae in an intensive care unit of a teaching hospital in Southwest China.

Extensively drug-resistant and hypervirulent Klebsiella pneumoniae (XDR-hvKp) is a new problem for patients in Intensive Care Unit (ICU) and can become an even more severe threat if resistant to tigecycline, considered one of the 'last lines of defense' drugs. This study collected seven non-replicated tigecycline-resistant XDR-hvKp from seven patients and performed genome analysis and epidemiological investigation using whole genome equencing (WGS) and other methods. All strains in this study were identified as ST11-KL64 and showed high resistance to antibiotics such as ß-lactams, aminoglycosides, quinolones, and tigecycline, and one strain was also resistant to colistin. All strains were determined to be hvKp by the results of serum resistance assay and Galleria mellonella infection models. All strains had resistance genes bla CTX-M-65,bla KPC-2,bla LAP-2,bla TEM-1B, rmtB, and qnrS1 and virulence factors such as rmpA, rmpA2, and aerobactin (iucABCD, iutA). The expression of the AcrAB-TolC efflux pump was upregulated in all strains, and the expression levels of the gene pmrK was significantly upregulated in colistin-resistant strain DP compared to colistin-sensitive strain WT in this study. In conclusion, we described an outbreak caused by tigecycline-resistant XDR-hvKp in the ICU of a teaching hospital in southwest China. The spread of these superbugs poses a great threat to patients and therefore requires us to closely monitor these XDR-hvKp and develop relevant strategies to combat them.

Phenotypic and Genotypic Characteristics of a Tigecycline-Resistant Acinetobacter pittii Isolate Carrying bla NDM-1 and the Novel bla OXA Allelic Variant bla OXA-1045.

A tigecycline-resistant Acinetobacter pittii clinical strain from pleural fluid carrying a bla NDM-1 gene and a novel bla OXA gene, bla OXA-1045, was isolated and characterized. The AP2044 strain acquired two copies of the bla NDM-1 gene and six antibiotic resistance genes (ARGs) from other pathogens. According to the whole-genome investigation, the GC ratios of ARGs (50-60%) were greater than those of the chromosomal backbone (39.46%), indicating that ARGs were horizontally transferred. OXA-1045 belonged to the OXA-213 subfamily and the amino acid sequence of OXA-1045 showed 89% similarity to the amino acid sequences of OXA-213. Then, bla OXA-1045 and bla OXA-213 were cloned and the minimum inhibitory concentrations (MICs) of ß-lactams in the transformants were determined using the broth microdilution method. OXA-1045 was able to confer a reduced susceptibility to piperacillin and piperacillin-tazobactam compared to OXA-213. AP2044 strain exhibited low pathogenicity in Galleria mellonella infection models. The observation of condensed biofilm using the crystal violet staining method and scanning electron microscopy (SEM) suggested that the AP2044 strain was a weak biofilm producer. Quantitative reverse transcription-PCR (qRT-PCR) was used to detect the expression of resistance-nodulation-cell division (RND) efflux pump-related genes. The transcription level of adeB and adeJ genes increased significantly and was correlated with tigecycline resistance. Therefore, our genomic and phenotypic investigations revealed that the AP2044 strain had significant genome plasticity and natural transformation potential, and the emergence of antibiotic resistance in these unusual bacteria should be a concern for future investigations.

The molecular characteristics, clinical manifestations, and risk factors of hypervirulent Klebsiella pneumoniae infections in a large teaching hospital in southwest China.

Hypervirulent Klebsiella pneumoniae (hvKp) has been globally disseminated recently, especially in Asia. The purpose of this study was to identify the molecular characteristics, clinical manifestations, and clinical risk factors of hvKp infections among patients in a large teaching hospital. A retrospective study was conducted in 123 patients infected with K. pneumoniae at the Affiliated Hospital of Southwest Medical University (Luzhou, China) from October 2016 to November 2018. An isolate that positive for both PCR amplification of aerobactin gene and Galleria mellonella infection model was defined as hvKp. Overall, 43.1% (53/123) of K. pneumoniae isolates were hvKp. String tests were performed on all isolates, and MLSTs of all hvKp were conducted. The K1 ST23 isolates were the dominant clone of hvKp (35.8%). Univariate analysis revealed the following risk factors for hvKp: hepatic abscess (OR = 41.818 [95% CI, 5.379-335.086]), bacteremia (OR = 19.94 [95% CI, 5.565-71.446]), metastatic spread (OR = 19.938 [95% CI, 6.344-62.654]), CRP (OR = 1.008 [95% CI, 1.001-1.015]), nitroimidazole treatment (OR = 7.907 [95% CI, 1.652-37.843]), diabetes (OR = 3.067 [95% CI, 1.38-6.817]), and admission to positive culture interval (OR = 3.636 [95% CI, 1.524-8.678]). Moreover, Multivariate analysis implicated hepatic abscess (OR = 74.332 [95% CI, 3.121-1769.588]), bacteremia (OR = 28.388 [95% CI, 3.039-264.200]), and metastatic spread (OR = 19.391 [95% CI, 3.633-103.498]) as independent risk factors for hvKp infections. Thirteen of twenty-one tested antibiotics were founded resistant to non-hvKp, which is significantly greater than hvKp. Importantly, the ESBL-hvKp and MDR-hvKp were responsible for 7.5% and 15.1% in the hvKp group, respectively.

Pathogenic Characteristics and Risk Factors for ESKAPE Pathogens Infection in Burn Patients.

OBJECTIVE: This study aimed to determine the clinical manifestations, antimicrobial resistance, molecular characteristics, and risk factors for ESKAPE pathogens infection in burn patients. METHODS: A retrospective study of 187 burn patients infected with ESKAPE pathogens was conducted at the Department of Plastic and Burn Surgery of the Affiliated Hospital of Southwest Medical University (Luzhou, China) from October 2018 to June 2021. All strains were identified using a MicroScan WalkAway 96 Plus System, and antimicrobial susceptibilities were determined using the VITEK system or the disk diffusion method. The antimicrobial resistance genes of multi-drug resistant ESKAPE (MDR-ESKAPE) were detected by polymerase chain reaction (PCR). The multivariable logistic regression analysis was used to estimate the risk factors for ESKAPE infection and MDR-ESKAPE infection. RESULTS: A total of 255 strains were isolated in various types of clinical specimens from 187 burn patients, of which 47.5% were ESKAPE pathogens (121/255). Among these, MDR-ESKAPE pathogens accounted for 55% (67/121). Additionally, aph3'III, mecA, bla SHV, bla TEM, bla PDC, and bla SHV were the most prevalent genes detected in Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp., respectively. The independent risk factors for ESKAPE infection were total body surface area (TBSA) >30-50% (odds ratio [OR] = 10.428; 95% confidence interval [CI], 2.047 to 53.108), TBSA >50% (OR = 15.534; 95% CI, 1.489 to 162.021), and parenteral nutrition (OR = 3.597; 95% CI, 1.098 to 11.787). No independent risk factors were found for MDR-ESKAPE infection. CONCLUSION: Clinical staff should be alert to the risk of nosocomial infection with ESKAPE pathogens in burn patients receiving parenteral nutrition and under TBSA >30%. Full attention should also be paid to the ESKAPE resistance, strict adherence to infection control protocols for the rational use of antimicrobial agents, and enhanced clinical standardization of antimicrobial agents management.

Carbapenem-Resistant Klebsiella pneumoniae in Southwest China: Molecular Characteristics and Risk Factors Caused by KPC and NDM Producers.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has attracted worldwide concern and became a serious challenge for clinical treatment. The aims of this study were to evaluate the molecular characteristics and risk factors for CRKP infection. METHODS: All the CRKP strains were screened for antimicrobial resistance genes, virulence genes, and integron by polymerase chain reaction (PCR). Plasmid typing was performed by plasmid conjugation assay and PCR-based replicon typing (PBRT). The genetic environments of bla KPC-2 and bla NDM-1 were analyzed by using overlapping PCR and molecular typing was performed by multi-locus sequence typing (MLST). Risk factors for CRKP infection were analyzed by logistic regression model. RESULTS: All the 66 CRKP isolates were multidrug-resistant, but all of them were susceptible to tigecycline and polymyxin B. Among the CRKP isolates, 42 bla KPC-2-positive strains were identified carrying IncFII plasmids. Meanwhile, 24 bla NDM-positive strains were found on lncX3 plasmids, including 20 bla NDM-1 isolates and 4 bla NDM-5 isolates. Most of CRKP isolates contained several virulence genes and the class I integron (intl1). The genetic environments of bla KPC-2 and bla NDM-1 revealed that the conserved regions (tnpA-tnpR-ISkpn8-bla KPC-2) and (bla NDM-1-ble MBL -trpF-tat) were associated with the dissemination of KPC-2 and NDM-1. ST11 was the most common type in this work. Hematological disease, tracheal cannula, and use of ß-lactams and ß-lactamase inhibitor combination were identified as independent risk factors for CRKP infection. CONCLUSION: This study established the resistance pattern, molecular characteristics, clonal relatedness, and risk factors of CRKP infection. The findings of the novel strain that co-harboring bla NDM-5 and bla IMP-4, and the novel ST4495 indicated that the brand-new types have spread in Southwest China, emphasizing the prevent and control the further dissemination of CRKP isolates are highly needed.

Antioxidant and antibacterial study of 10 flavonoids revealed rutin as a potential antibiofilm agent in Klebsiella pneumoniae strains isolated from hospitalized patients.

The emergence of multidrug resistance (MDR) and extensive drug resistance (XDR) in Klebsiella pneumoniae strains has posed great threats to conventional antibiotics. Previous studies have shown that plant-derived flavonoids have inhibitory functions against pathogens. However, in K. pneumoniae, the antibacterial activity of different flavonoids against growth and biofilm formation remains a mystery. The aim of the present study was to evaluate the antioxidant abilities of different flavonoids, to screen active ingredients and to identify their inhibitory effects on K. pneumoniae growth and biofilm formation. In total, 10 flavonoids representing 4 major categories were screened and used in this study. The antioxidant capacity of each flavonoid was evaluated through a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. Rutin showed the highest level of free radical scavenging capacity, followed by kaempferol, luteolin, quercetin, apigenin, hesperidin, sinensetin, naringenin, naringin and 3,5,6,7,8,3',4'-heptamethoxyflavone. The inhibitory effects of rutin and naringin on bacterial growth were also compared. The lowest MICs of rutin were found against K. pneumoniae ATCC700603 (1024 µg/mL) and E. coli ATCC25922 (512 µg/mL). However, the MBICs were not found. Rutin showed strong inhibitory ability against both the growth curve and biofilm production. The expression profiles of 15 biofilm-related genes were analyzed in biofilm cells both with and without rutin treatment. The luxS gene and wabG gene were downregulated significantly by rutin treatment. Correlation analysis showed that mrkA gene expression was positively correlated with biofilm biomass accumulation. Our study indicated that biofilm production is correlated with the expression of several genes rather than one. MrkA gene expression was positively correlated with biofilm biomass accumulation. Our study screened rutin as a potential agent to inhibit K. pneumoniae biofilm formation.

Phenotypic and Genotypic Characteristics of Biofilm Formation in Clinical Isolates of Acinetobacter baumannii.

BACKGROUND: Acinetobacter baumannii is an important pathogen in clinical infections, and biofilm formation is an effective way for A. baumannii to survive under external pressures. In this study, the aims were to examine the antimicrobial resistance, biofilm formation, and biofilm-specific resistance in clinical isolates of A. baumannii. MATERIALS AND METHODS: A total of 104 clinical A. baumannii isolates were collected from a large teaching hospital in Southwest China. The antibiotics susceptibilities were tested, and biofilm-forming ability was evaluated by crystal violet staining by confocal laser scanning microscopy (CLSM). Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) of ciprofloxacin, meropenem, and ceftazidime were tested on selected strains by broth microdilution method. Biofilm-associated genes were detected by polymerase chain reaction (PCR), and expression of genes at planktonic stage and biofilm stage were analyzed by real-time reverse transcription PCR (RT-PCR). RESULTS: Multidrug-resistant (MDR) isolates accounted for 65.4%, but no strain was resistant to tigecycline and polymyxin B. Moreover, non-MDR strains tended to form stronger biofilms than MDR strains, and a negative correlation between biofilm-forming ability and resistance profiles to each of tested antimicrobials were observed. The MBECs and MBICs of ciprofloxacin, ceftazidime, and meropenem were evidently increased compared with MICs and MBCs among all tested strains. Additionally, the biofilm formation ability of the csuD-positive strains was stronger than that of the csuD-negative strains. The strains in MDR group had higher carrying rate of csuA and csuD genes than non-MDR group, while non-MDR strains possessed more ompA gene than MDR group. Finally, abaI gene was significantly up-regulated after biofilm formation. CONCLUSION: These results revealed valuable data for the negative correlation between antimicrobial resistance and biofilm formation, as well as phenotypic and genotypic characteristics of biofilm formation in A. baumannii.