OBJECTIVE: To compare the efficacy and safety of intravenous colistin sulfate combined with nebulized inhalation versus intravenous monotherapy for pulmonary infections caused by carbapenem-resistant organism (CRO). METHODS: A multicenter retrospective cohort study was conducted. Clinical data were collected from patients admitted to the intensive care unit (ICU) of 10 tertiary class-A hospitals in Henan Province between July 2021 and May 2023, who received colistin sulfate for CRO pulmonary infections. Data included baseline characteristics, inflammatory markers [white blood cell count (WBC), neutrophil count (NEU), procalcitonin (PCT), C-reactive protein (CRP)], renal function indicators [serum creatinine (SCr), blood urea nitrogen (BUN)], life support measures, anti-infection regimens, clinical efficacy, microbiological clearance rate, and prognostic outcomes. Patients were divided into two groups: intravenous group (colistin sulfate monotherapy via intravenous infusion) and combination group ((intravenous infusion combined with nebulized inhalation of colistin sulfate). Changes in parameters before and after treatment were analyzed. RESULTS: A total of 137 patients with CRO pulmonary infections were enrolled, including 89 in the intravenous group and 48 in the combination group. Baseline characteristics, life support measures, daily colistin dose, and combination regimens (most commonly colistin sulfate plus carbapenems in both groups) showed no significant differences between two groups. The combination group exhibited higher clinical efficacy [77.1% (37/48) vs. 59.6% (52/89)] and microbiological clearance rate [60.4% (29/48) vs. 39.3% (35/89)], both P < 0.05. Pre-treatment inflammatory and renal parameters showed no significant differences between two groups. Post-treatment, the combination group showed significantly lower WBC and CRP [WBC (×10⁹/L): 8.2±0.5 vs. 10.9±0.6, CRP (mg/L): 14.0 (5.7, 26.6) vs. 52.1 (24.4, 109.6), both P < 0.05], whereas NEU, PCT, SCr, and BUN levels showed no significant between two groups. ICU length of stay was shorter in the combination group [days: 16 (10, 25) vs. 21 (14, 29), P < 0.05], although mechanical ventilation duration and total hospitalization showed no significant differences between two groups. CONCLUSIONS Intravenous colistin sulfate combined with nebulized inhalation improved clinical efficacy and microbiological clearance in CRO pulmonary infections with an acceptable safety profile.
Humans ; Colistin/therapeutic use* ; Retrospective Studies ; Administration, Inhalation ; Anti-Bacterial Agents/therapeutic use* ; Carbapenems/pharmacology* ; Male ; Female ; Middle Aged ; Gram-Negative Bacteria/drug effects* ; Aged ; Treatment Outcome ; Respiratory Tract Infections/drug therapy*

Membrane vesicles (MVs) are non-replicating spherical nanoparticles produced by bacteria. The MVs actively released from Gram-negative bacteria are termed outer membrane vesicles (OMVs). OMVs carry various biomolecules, such as lipopolysaccharides, peptidoglycans, proteins, and nucleic acids for material exchange between cells and perform component-dependent physiological functions. In recent years, OMVs have been developed into various biological products, such as vaccines, adjuvants, drug delivery carriers, and cancer immunotherapy agents because of their unique structures and functions. This review describes the biogenesis, composition, and physiological functions of OMVs of Gram-negative bacteria, summarizes the recent research progress of OMVs in product development and cell modifications or engineering, highlights new methods for OMV preparation and characterization, and provides an outlook on the future research directions, with the aim to provide a good reference for study and development of the application of OMVs in the biomedical field.
Gram-Negative Bacteria/metabolism* ; Bacterial Outer Membrane/metabolism* ; Bacterial Outer Membrane Proteins/metabolism* ; Lipopolysaccharides/metabolism*

N-dodecanoyl-l-homoserine lactone (C12-HSL) is a signaling molecule that mediates bacterial quorum sensing, regulating bacterial population behaviors. This study investigated the effects of C12-HSL on the isolation and cultivation of gut microbiota, with the goal of enriching the diversity and number of cultivable bacterial strains from the mouse gut microbiota. Using a culture medium supplemented with C12-HSL, we isolated and cultivated bacterial strains from mouse intestinal contents, obtaining a total of 235 isolates. Preliminary identification based on the 16S rRNA gene revealed 54 bacterial species, including 4 potential new species, 4 potential new genera and 1 potential new family. Compared with the previously established mouse gut microbial biobank (mGMB), this study newly identified 42 bacterial species, enhancing the diversity of the strain library. Statistical analysis showed that the proportion of Gram-negative bacteria, particularly those belonging to Proteobacteria, isolated by this method was significantly higher than that obtained by conventional isolation and cultivation methods without the addition of C12-HSL. Subsequent cultivation experiments with one of the newly discovered bacterial species indicated that exogenous C12-HSL at 20-200 μmol/L significantly promoted the growth of this species, while higher concentrations of C12-HSL significantly reduced the cell density of this bacterium. This work confirms that quorum sensing molecules, such as C12-HSL, can enhance the growth, isolation, and cultivation of Gram-negative bacteria in the gut within a specific concentration range. Although the mechanism by which C12-HSL promotes the growth of gut bacterial strains requires further investigation, the findings of this study provide new insights into the targeted isolation, cultivation, and regulation of gut microbiota using bacterial quorum sensing signal molecules.
Animals ; Mice ; Acyl-Butyrolactones/pharmacology* ; Gastrointestinal Microbiome/drug effects* ; Quorum Sensing ; Gram-Negative Bacteria/classification* ; Intestines/microbiology* ; RNA, Ribosomal, 16S/genetics* ; Culture Media

OBJECTIVES: Bloodstream infections in emergency patients have a high incidence, severe disease progression, and rapid deterioration. Early administration of appropriate antimicrobial agents is crucial for improving patient outcomes. This study aims to investigate the incidence, pathogen distribution, and antimicrobial resistance patterns of bloodstream infections in emergency patients, providing a reference for rational antibiotic use in clinical practice. METHODS: Medical records of patients diagnosed with bloodstream infections in the emergency department of a hospital in Hunan Province between January 2018 and October 2022 were retrospectively collected. Clinical characteristics of bloodstream infection patients were analyzed, and the distribution trends and antimicrobial susceptibility of clinical isolates were examined. RESULTS: During the study period, 2 215 blood culture samples were submitted from the emergency department, with a positivity rate of 13.27%. After excluding eight cases with missing data or suspected contamination, 286 patients with bloodstream infections were included, with community-acquired infections accounting for the majority (85.66%). The most common primary infection site was the urinary tract (24.48%), followed by respiratory tract infections (20.28%) and biliary and intra-abdominal infections (17.13%). The 30-day mortality rate of bloodstream infections was 16.08%. A total of 286 pathogens were isolated, including 181 (63.29%) Gram-negative bacteria, primarily Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa; 101 (35.31%) Gram-positive bacteria, mainly Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pneumoniae; and only 4 (1.40%) fungal isolates. Antimicrobial susceptibility testing showed that the key Enterobacteriaceae strains exhibited resistance rates of 2.4% to carbapenems, 16.3% to piperacillin sodium and tazobactam sodium, and 15.3% to ceftazidime, with no detected resistance to tigecycline or polymyxins. The main non-fermentative bacteria showed resistance rates of 29.6% to piperacillin sodium and tazobactam sodium, 13.3% to cefoperazone sodium and sulbactam sodium, and 27.1% to quinolones. Among Gram-negative bacteria, multidrug-resistant strains accounted for 40.9% (74/181), with carbapenem-resistant Escherichia coli and Klebsiella pneumoniae detected in 5.4% (5/92) and 13.6% (6/44) of cases, respectively. No carbapenem-resistant Pseudomonas aeruginosa was identified. Among Gram-positive bacteria, resistance rates to penicillin G, rifampicin, and cefoxitin were 74.7%, 4.2%, and 50%, respectively, with only 3 cases of resistant to glycopeptide antibiotics. CONCLUSIONS Bloodstream infections in emergency patients are predominantly community-acquired, with Gram-negative bacteria being the most common pathogens. The isolated pathogens exhibited relatively low resistance rates to commonly used clinical antibiotics.
Retrospective Studies ; Emergency Service, Hospital/statistics & numerical data* ; Drug Resistance, Bacterial ; Anti-Bacterial Agents/therapeutic use* ; Incidence ; Microbial Sensitivity Tests/statistics & numerical data* ; Bacteremia/microbiology* ; Community-Acquired Infections/microbiology* ; Gram-Negative Bacteria/isolation & purification* ; Blood Culture/statistics & numerical data* ; Humans ; Male ; Female ; Adolescent ; Young Adult ; Adult ; Middle Aged ; Aged ; Aged, 80 and over ; China/epidemiology*

Objective: To study the incidence of bloodstream infections, pathogen distribution, and antibiotic resistance profile in patients with hematological malignancies. Methods: From January 2018 to December 2021, we retrospectively analyzed the clinical characteristics, pathogen distribution, and antibiotic resistance profiles of patients with malignant hematological diseases and bloodstream infections in the Department of Hematology, Nanfang Hospital, Southern Medical University. Results: A total of 582 incidences of bloodstream infections occurred in 22,717 inpatients. From 2018 to 2021, the incidence rates of bloodstream infections were 2.79%, 2.99%, 2.79%, and 2.02%, respectively. Five hundred ninety-nine types of bacteria were recovered from blood cultures, with 487 (81.3%) gram-negative bacteria, such as Klebsiella pneumonia, Escherichia coli, and Pseudomonas aeruginosa. Eighty-one (13.5%) were gram-positive bacteria, primarily Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecium, whereas the remaining 31 (5.2%) were fungi. Enterobacteriaceae resistance to carbapenems, piperacillin/tazobactam, cefoperazone sodium/sulbactam, and tigecycline were 11.0%, 15.3%, 15.4%, and 3.3%, with a descending trend year on year. Non-fermenters tolerated piperacillin/tazobactam, cefoperazone sodium/sulbactam, and quinolones at 29.6%, 13.3%, and 21.7%, respectively. However, only two gram-positive bacteria isolates were shown to be resistant to glycopeptide antibiotics. Conclusions: Bloodstream pathogens in hematological malignancies were broadly dispersed, most of which were gram-negative bacteria. Antibiotic resistance rates vary greatly between species. Our research serves as a valuable resource for the selection of empirical antibiotics.
Humans ; Bacteremia/epidemiology* ; Cefoperazone ; Sulbactam ; Retrospective Studies ; Drug Resistance, Bacterial ; Microbial Sensitivity Tests ; Hematologic Neoplasms ; Sepsis ; Anti-Bacterial Agents/pharmacology* ; Gram-Negative Bacteria ; Gram-Positive Bacteria ; Piperacillin, Tazobactam Drug Combination ; Escherichia coli

OBJECTIVE: To analyze the distribution and drug resistance of pathogens in oral mucositis associated with chemotherapy in hospitalized patients with malignant hematopathy, so as to provide scientific evidences for rational selection of antibiotics and infection prevention and control. METHODS: From July 2020 to June 2022, 167 patients with malignant hematopathy were treated with chemical drugs in the Department of Hematology, Hainan Hospital, and secretions from oral mucosal infected wounds were collected. VITEK2 COMPECT automatic microbial identification system (BioMerieux, France) and bacterial susceptibility card (BioMerieux) were used for bacterial identification and drug susceptibility tests. RESULTS: A total of 352 strains of pathogens were isolated from 167 patients, among which 220 strains of Gram-positive bacteria, 118 strains of Gram-negative bacteria and 14 strains of fungi, accounted for 62.50%, 33.52% and 3.98%, respectively. The Gram-positive bacteria was mainly Staphylococcus and Streptococcus, while Gram-negative bacteria was mainly Klebsiella and Proteus. The resistance of main Gram-positive bacteria to vancomycin, ciprofloxacin and gentamicin was low, and the resistance to penicillin, cefuroxime, ampicillin, cefotaxime, erythromycin and levofloxacin was high. The main Gram-negative bacteria had low resistance to gentamicin, imipenem and penicillin, but high resistance to levofloxacin, cefotaxime, cefuroxime, ampicillin and vancomycin. The clinical data of oral mucositis patients with oral ulcer (severe) and without oral ulcer (mild) were compared, and it was found that there were statistically significant differences in poor oral hygiene, diabetes, sleep duration less than 8 hours per night between two groups (P<0.05). CONCLUSION Gram-positive bacteria is the main pathogen of oral mucositis in patients with malignant hematopathy after chemotherapy. It is sensitive to glycopeptide antibiotics and aminoglycosides antibiotics. Poor oral hygiene, diabetes and sleep duration less than 8 hours per night are risk factors for oral mucositis with oral ulcer (severe).
Humans ; Vancomycin/therapeutic use* ; Cefuroxime ; Levofloxacin ; Oral Ulcer/drug therapy* ; Drug Resistance, Bacterial ; Anti-Bacterial Agents/adverse effects* ; Ampicillin ; Penicillins ; Cefotaxime ; Gram-Positive Bacteria ; Gram-Negative Bacteria ; Gentamicins ; Stomatitis/drug therapy*

Stenotrophomonas species are non-fermentative Gram-negative bacteria that are widely distributed in environment and are highly resistant to numerous antibiotics. Thus, Stenotrophomonas serves as a reservoir of genes encoding antimicrobial resistance (AMR). The detection rate of Stenotrophomonas is rapidly increasing alongside their strengthening intrinsic ability to tolerate a variety of clinical antibiotics. This review illustrated the current genomics advances of antibiotic resistant Stenotrophomonas, highlighting the importance of precise identification and sequence editing. In addition, AMR diversity and transferability have been assessed by the developed bioinformatics tools. However, the working models of AMR in Stenotrophomonas are cryptic and urgently required to be determined. Comparative genomics is envisioned to facilitate the prevention and control of AMR, as well as to gain insights into bacterial adaptability and drug development.
Stenotrophomonas/genetics* ; Drug Resistance, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Gram-Negative Bacteria ; Genomics ; Microbial Sensitivity Tests

OBJECTIVE: To investigate the distribution and drug sensitivity of pathogenic bacteria isolated from patients in hematology department, in order to provide evidence for rational use of antibiotics in clinic. METHODS: The distribution of pathogenic bacteria and drug sensitivity data of patients in the hematology department of The First Affiliated Hospital of Nanjing Medical University from 2015 to 2020 were retrospectively analyzed, and the pathogens isolated from different specimen types were compared. RESULTS: A total of 2 029 strains of pathogenic bacteria were isolated from 1 501 patients in the hematology department from 2015 to 2020, and 62.2% of which were Gram-negative bacilli, mainly Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Acinetobacter baumannii. Gram-positive coccus accounted for 18.8%, mainly Coagulase-negative staphylococcus (CoNS) and Staphylococcus aureus. Fungi (17.4%) were mainly candida. The 2 029 strains were mainly isolated from respiratory tract (35.1%), blood (31.8%) and urine (19.2%) specimens. Gram-negative bacilli were the main pathogenic bacteria in different specimen types (>60%). K. pneumoniae, S. maltophilia and A. baumannii were the most common pathogens in respiratory specimens, E. coli, CoNS, K. pneumoniae and P. aeruginosa were common in blood samples, and E. coli and Enterococcus were most common in urine samples. Enterobacteriaceae had the highest susceptibility to amikacin and carbapenems (>90.0%), followed by piperacillin/tazobactam. P. aeruginosa strains had high sensitivity to antibiotics except aztreonam (<50.0%). The susceptibility of A. baumannii to multiple antibiotics was less than 70.0%. The antimicrobial resistance rates of E. coli and K. pneumoniae in respiratory tract specimens were higher than those in blood specimens and urine specimens. CONCLUSION Gram-negative bacilli are the main pathogenic bacteria isolated from patients in hematology department. The distribution of pathogens is different in different types of specimens, and the sensitivity of each strain to antibiotics is different. The rational use of antibiotics should be based on different parts of infection to prevent the occurrence of drug resistance.
Humans ; Escherichia coli ; Retrospective Studies ; Bacteria ; Anti-Bacterial Agents/therapeutic use* ; Gram-Negative Bacteria ; Drug Resistance ; Pseudomonas aeruginosa ; Hematology

OBJECTIVE: To investigate the efficacy and safety of colistin sulfate in the treatment of hematonosis patients infected by multidrug-resistant (MDR) gram-negative bacteria (GNB), and discuss the possible factors that affect the efficacy of colistin sulfate. METHODS: The clinical data of 85 hematologic patients infected with MDR GNB in the Soochow Hopes Hematonosis Hospital from April 2022 to November 2022 were collected and divided into clinically effective group with 71 cases and ineffective group with 14 cases according to the therapeutic efficacy of colistin sulfate. The age, gender, type of hematologic disease, status of hematopoietic stem cell transplantation, infection sites, type of pathogen, timing of administration, daily dose and duration of colistin sulfate, and combination with other antibacterial agents of patients in two groups were compared. Logistic regression was used to analyze on the meaningful variables to study the influencing factors of colistin sulfate. The adverse reactions of colistin sulfate were also evaluated. RESULTS: There were no significant differences in age, gender, type of hematologic disease, hematopoietic stem cell transplantation status, infection sites and pathogen type between the effective group and the ineffective group (P>0.05). Compared with the medication time more than 7 days, meropenem used within 7 days in the clinical effective group, and timely replacement with colistin sulfate could obtain better efficacy, the difference was statistically significant (P=0.018). The duration of tigacycline before colistin sulfate did not affect the efficacy, and there was no significant difference in efficacy between the effective and ineffective groups. The therapeutic effect of colistin sulfate at daily dose of 500 000 U q8h was better than that of 500 000 U q12h, the difference was statistically significant (P=0.035). The time of colistin sulfate use in the clinically effective group was longer than that in the ineffective group, which had a statistical difference (P=0.003). Compared with the clinical ineffective group, the efficacy of combination regimens with colistin sulfate was better than that of colistin sulfate monotherapy, and the difference was statistically significant (P=0.013). Multivariate logistic regression analysis was performed on the indicators with statistical differences in the two groups of patients, which suggested that the use time of colistin sulfate (B: 2.358; OR: 10.573; CI: 1.567-71.361; P=0.015) and the combination of colistin sulfate (B: 1.720; OR: 5.586; CI: 1.210-25.787; P=0.028) were influential factors in the efficacy of colistin sulfate. During the treatment, the incidence of nephrotoxicity, hepatotoxicity and peripheral neurotoxicity were 5.9%, 1.2% and 1.2%, respectively. CONCLUSION The use of colistin sulfate improves the clinical efficacy of MDR GNB infections in hematological patients, and the timing of colistin sulfate administration and the combination of drugs are independent factors affecting its clinical efficacy, and the safety during treatment is high.
Humans ; Colistin/adverse effects* ; Anti-Bacterial Agents/therapeutic use* ; Meropenem/adverse effects* ; Treatment Outcome ; Gram-Negative Bacteria ; Hematologic Diseases

Objective: To understand the characteristics of bacterial meningitis after pediatric neurosurgical procedures. Methods: This was a retrospective observational study. From January 2016 to December 2022, 64 children diagnosed with post-neurosurgical bacterial meningitis based on positive cerebrospinal fluid (CSF) culture in Department of Neurosurgery of Shanghai Children's Medical Center were selected as the study population. The clinical characteristics, onset time, routine biochemical indexes of cerebrospinal fluid before anti infection treatment, bacteriology characteristics and sensitivity to antibiotics of bacteria cultured from cerebrospinal fluid were analyzed. Based on the CSF culture results, the patients were divided into the Gram-positive bacteria infection group and the Gram-negative bacteria infection group. The clinical characteristics of the two groups were compared using t-tests or Wilcoxon rank-sum tests, and chi-square tests. Results: There were 64 children,42 boys and 22 girls, with onset age of 0.83 (0.50, 1.75) years. Seventy cases of post-neurosurgical bacterial meningitis occurred in the 64 children, of which 15 cases (21%) in spring, 23 cases (33%) in summer, 19 cases (27%) in autumn, and 13 cases (19%) in winter. The time of onset was 3.5 (1.0, 10.0) months after surgery; 15 cases (21%) occurred within the first month after the surgery, and 55 cases (79%) occurred after the first month. There were 38 cases (59%) showing obvious abnormal clinical manifestations, fever 36 cases (56%), vomiting 11 cases (17%). Forty-eight cases (69%) were caused by Gram-positive bacteria, with Staphylococcus epidermidis 24 cases; 22 cases (31%) were caused by Gram-negative bacteria, with Acinetobacter baumannii the prominent pathogen 7 cases. The Gram-positive bacterial infection was more common in summer than the Gram-negative bacterial infection (20 cases (42%) vs. 3 cases (14%), χ²=5.37, P=0.020), while the Gram-negative bacterial infection was more in autumn and within the first month after surgery than the Gram-positive bacterial infection (11 cases (50%) vs. 8 cases (17%), 15 cases (67%) vs. 5 cases (33%), χ²=8.48, 9.02; P=0.004, 0.003). Gram-positive bacteria resistant to vancomycin and Acinetobacter baumannii resistant to polymyxin were not found. However, Acinetobacter baumannii showed only 45% (10/22) susceptibility to carbapenem antibiotics. Conclusions: The clinical presentation of post-neurosurgical bacterial meningitis in children is atypical. Gram-positive bacteria are the main pathogens causing post-neurosurgical bacterial meningitis; Gram-negative bacterial meningitis are more likely to occur in autumn and within the first month after surgery. Acinetobacter baumannii has a high resistance rate to carbapenem antibiotics, which should be taken seriously.
Male ; Female ; Humans ; Child ; China/epidemiology* ; Anti-Bacterial Agents/pharmacology* ; Meningitis, Bacterial/diagnosis* ; Gram-Negative Bacterial Infections/drug therapy* ; Gram-Positive Bacteria ; Gram-Positive Bacterial Infections/drug therapy* ; Carbapenems ; Retrospective Studies ; Microbial Sensitivity Tests ; Drug Resistance, Bacterial