BACKGROUND

Infections of the central nervous system may develop in patients with traumatic brain injury after the implant of external ventricular drainage catheters or after neurological surgeries.

We report the case of a woman in her 50s who was admitted with a subarachnoid hemorrhage secondary to a ruptured aneurysm, for which she underwent a tube ventriculostomy with an external ventricular drain attached and developed neurosurgical meningitis. The cerebrospinal fluid culture showed the presence of multidrug-resistant Acinetobacter baumannii. Intrathecal delivery of 65,000 units of colistin methyl sodium twice daily with a clamp drain for 15 to 60 min after administration was used as treatment. After 72 hours of treatment, the patient's infection improved, and repeat cerebrospinal fluid culture showed no microbial growth.

Intrathecal colistin can be used as a treatment for multidrug-resistant A. baumannii meningitis.

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*

Bacillus is a class of spore-producing Gram-positive bacteria that produce a variety of antimicrobial substances with different structures and functions. The application of the antimicrobial substances produced by Bacillus can effectively inhibit the activity of harmful bacteria and fungi and promote the sustainable development of green agriculture. The antimicrobial substances produced by Bacillus mainly include proteins, lipopeptides, polyketones, and polypeptides. This paper reviews the synthesis gene clusters, synthesis pathways, structures, and mechanisms of various antimicrobial substances produced by Bacillus and discusses the challenges in the industrial application of these antimicrobial substances. Furthermore, this paper clarifies the future research and development focuses and prospects the application prospects, and provides comprehensive theoretical support for the in-depth research and wide application of the antimicrobial substances produced by Bacillus.
Bacillus/genetics* ; Anti-Infective Agents/metabolism* ; Bacterial Proteins/genetics* ; Antimicrobial Peptides/biosynthesis* ; Lipopeptides/biosynthesis*

Background: Multidrug-resistant gram-negative (MDR GN) infections pose a significant threat to pediatric health. One of the treatment options in resource-limited settings is polymyxin-based combination therapy. However, evidence on the safety and clinical effectiveness of polymyxin B in children is scarce. Objectives: This study described the outcomes of mortality, bacteriologic cure and clinical response in pediatric patients with MDR GN infections treated with polymyxin-B-based combination therapy. Adverse drug events (ADE) are likewise described. Methodology: This is a retrospective descriptive study conducted at the Philippine General Hospital (PGH) among pediatric inpatients from December 2020 to June 2023 with MDR GN infections treated with polymyxin B (PmB), combined with at least one other antibiotic with gram-negative coverage for at least 48 hours. Frequency and rates of the outcomes were measured and analyzed, in relation to the bacterial groups (Enterobacterales, Acinetobacter spp., Pseudomonas aeruginosa) and combination antibiotic regimens used, i.e., meropenem- and fluoroquinolone-containing regimen (PmB+MEM vs PmB+FQ). Frequency of ADEs were measured. Results: A total of 172 cases in 136 patients were reviewed. The rates for 14-day mortality, failure in bacteriologic cure, and failure in clinical response were 26%, 15%, and 19%, respectively. In Enterobacterales infections, PmB+FQ demonstrated lower rates of mortality, failure in bacteriologic cure, and failure in clinical responses. On the other hand, in Acinetobacter infections, PmB+MEM numerically had lower rates for the same outcomes. The Pseudomonas group had conflicting data on which regimen is numerically more favorable overall. No statistically significant differences were found in the outcomes. ADEs noted were tubulopathy (5 cases), anaphylaxis (2 cases), and neurotoxicity (1 case). Conclusion Polymyxin-B-based combination therapy appears to be an acceptable treatment option for MDR GN infections in children, especially in settings where novel antibiotics are not accessible. Safety profiles indicate common but manageable adverse effects.
Polymyxin B ; Child

Lysobacter harbors a plethora of cryptic biosynthetic gene clusters (BGCs), albeit only a limited number have been analyzed to date. In this study, we described the activation of a cryptic polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) gene cluster (lsh) in Lysobacter sp. DSM 3655 through promoter engineering and heterologous expression in Streptomyces sp. S001. As a result of this methodology, we were able to isolate two novel linear lipopeptides, lysohexaenetides A (1) and B (2), from the recombinant strain S001-lsh. Furthermore, we proposed the biosynthetic pathway for lysohexaenetides and identified LshA as another example of entirely iterative bacterial PKSs. This study highlights the potential of heterologous expression systems in uncovering cryptic biosynthetic pathways in Lysobacter genomes, particularly in the absence of genetic manipulation tools.
Lysobacter/metabolism* ; Streptomyces/metabolism* ; Lipopeptides/metabolism* ; Polyketide Synthases/genetics* ; Multigene Family

Objective:b> To assess the efficacy and safety of polymyxin B in neutropenic patients with hematologic disorders who had refractory gram-negative bacterial bloodstream infection. Methods:b> From August 2021 to July 2022, we retrospectively analyzed neutropenic patients with refractory gram-negative bacterial bloodstream infection who were treated with polymyxin B in the Department of Hematology of the First Affiliated Hospital of the Soochow University between August 2021 to July 2022. The cumulative response rate was then computed. Results:b> The study included 27 neutropenic patients with refractory gram-negative bacterial bloodstream infections. Polymyxin B therapy was effective in 22 of 27 patients. The median time between the onset of fever and the delivery of polymyxin B was 3 days [interquartile range (IQR) : 2-5]. The median duration of polymyxin B treatment was 7 days (IQR: 5-11). Polymyxin B therapy had a median antipyretic time of 37 h (IQR: 32-70). The incidence of acute renal dysfunction was 14.8% (four out of 27 cases), all classified as "injury" according to RIFLE criteria. The incidence of hyperpigmentation was 59.3%. Conclusion:b> Polymyxin B is a viable treatment option for granulocytopenia patients with refractory gram-negative bacterial bloodstream infections.
Humans ; Polymyxin B/adverse effects* ; Retrospective Studies ; Gram-Negative Bacterial Infections/complications* ; Fever/drug therapy* ; Sepsis/drug therapy* ; Anti-Bacterial Agents/therapeutic use* ; Bacteremia/complications*

OBJECTIVES: Gram-positive cocci is the main pathogen responsible for early infection after liver transplantation (LT), posing a huge threat to the prognosis of liver transplant recipients. This study aims to analyze the distribution and drug resistance of Gram-positive cocci, the risk factors for infections and efficacy of antibiotics within 2 months after LT, and to guide the prevention and treatment of these infections. METHODS: In this study, data of pathogenic bacteria distribution, drug resistance and therapeutic efficacy were collected from 39 Gram-positive cocci infections among 256 patients who received liver transplantation from donation after citizens' death in the Third Xiangya Hospital of Central South University from January 2019 to July 2022, and risk factors for Gram-positive cocci infection were analyzed. RESULTS: Enterococcus faecium was the dominant pathogenic bacteria (33/51, 64.7%), followed by Enterococcus faecalis (11/51, 21.6%). The most common sites of infection were abdominal cavity/biliary tract (13/256, 5.1%) and urinary tract (10/256, 3.9%). Fifty (98%) of the 51 Gram-positive cocci infections occurred within 1 month after LT. The most sensitive drugs to Gram-positive cocci were teicoplanin, tigecycline, linezolid and vancomycin. Vancomycin was not used in all patients, considering its nephrotoxicity. Vancomycin was not administered to all patients in view of its nephrotoxicity.There was no significant difference between the efficacy of daptomycin and teicoplanin in the prevention of cocci infection (P>0.05). Univariate analysis indicated that preoperative Model for End-Stage Liver Disease (MELD) score >25 (P=0.005), intraoperative red blood cell infusion ≥12 U (P=0.013) and exposure to more than 2 intravenous antibiotics post-LT (P=0.003) were related to Gram-positive cocci infections. Multivariate logistic regression analysis revealed that preoperative MELD score >25 (OR=2.378, 95% CI 1.124 to 5.032, P=0.024) and intraoperative red blood cell transfusion ≥ 12 U (OR=2.757, 95% CI 1.227 to 6.195, P=0.014) were independent risk factors for Gram-positive cocci infections after LT. Postoperative Gram-positive cocci infections were reduced in LT recipients exposing to more than two intravenous antibiotics post-LT (OR=0.269, 95% CI 0.121 to 0.598, P=0.001). CONCLUSIONS Gram-positive cocci infections occurring early after liver transplantation were dominated by Enterococcus faecalis infections at the abdominal/biliary tract and urinary tract. Teicoplanin, tigecycline and linezolid were anti-cocci sensitive drugs. Daptomycin and teicoplanin were equally effective in preventing cocci infections due to Gram-positive cocci. Patients with high preoperative MELD score and massive intraoperative red blood cell transfusion were more likely to suffer Gram-positive cocci infection after surgery. Postoperative Gram-positive cocci infections were reduced in recipients exposing to more than two intravenous antibiotics post-LT.
Humans ; Daptomycin/therapeutic use* ; Linezolid/therapeutic use* ; Teicoplanin/therapeutic use* ; Gram-Positive Cocci ; Liver Transplantation/adverse effects* ; Tigecycline/therapeutic use* ; End Stage Liver Disease/drug therapy* ; Gram-Positive Bacterial Infections/microbiology* ; Severity of Illness Index ; Anti-Bacterial Agents/pharmacology* ; Vancomycin/therapeutic use* ; Microbial Sensitivity Tests

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:b> To investigate the antimicrobial resistance of food-borne diarrheagenic Escherichia coli (DEC) and the prevalence of mcr genes that mediates mobile colistin resistance in parts of China, 2020. Methods:b> For 91 DEC isolates recovered from food sources collected from Fujian province, Hebei province, Inner Mongolia Autonomous Region and Shanghai city in 2020, Vitek2 Compact biochemical identification and antimicrobial susceptibility testing platform was used for the detection of antimicrobial susceptibility testing (AST) against to 18 kinds of antimicrobial compounds belonging to 9 categories, and multi-polymerase chain reaction (mPCR) was used to detect the mcr-1-mcr-9 genes, then a further AST, whole genome sequencing (WGS) and bioinformatics analysis were platformed for these DEC isolates which were PCR positive for mcr genes. Results:b> Seventy in 91 isolates showed different antimicrobial resistance levels to the drugs tested with a resistance rate of 76.92%. The isolates showed the highest antimicrobial resistance rates to ampicillin (69.23%, 63/91) and trimethoprim-sulfamethoxazole (59.34%, 54/91), respectively. The multiple drug-resistant rate was 47.25% (43/91). Two mcr-1 gene and ESBL (extended-spectrum beta-lactamase) positive EAEC (enteroaggregative Escherichia coli) strains were detected. One of them was identified as serotype of O11:H6, which showed a resistance profile to 25 tested drugs referring to 10 classes, and 38 drug resistance genes were predicted by genome analysis. The other one was O16:H48 serotype, which was resistant to 21 tested drugs belonging to 7 classes and carried a new variant of mcr-1 gene (mcr-1.35). Conclusion:b> An overall high-level antimicrobial resistance was found among foodborne DEC isolates recovered from parts of China in 2020, and so was the MDR (multi-drug resistance) condition. MDR strains carrying multiple resistance genes such as mcr-1 gene were detected, and a new variant of mcr-1 gene was also found. It is necessary to continue with a dynamic monitoring on DEC contamination and an ongoing research into antimicrobial resistance mechanisms.
Humans ; Colistin/pharmacology* ; Anti-Bacterial Agents/pharmacology* ; Escherichia coli Infections/epidemiology* ; Escherichia coli Proteins/genetics* ; Drug Resistance, Bacterial/genetics* ; China/epidemiology* ; Escherichia coli ; Plasmids/genetics* ; Microbial Sensitivity Tests

Objective:b> Analysis and investigation of pathogenic characteristics of polymyxin-and carbapenem-resistant Klebsiella pneumoniae (PR-CRKP). Methods:b> A total of 23 PR-CRKP strains isolated from clinical specimens from the General Hospital of Southern Theater Command from March 2019 to July 2021 were retrospectively collected, Whole-genome sequencing was performed on 23 PR-CRKP strains, resistance genes were identified by comparison of the CARD and the ResFinder database, high-resolution typing of PR-CRKP strains was analyzed by core genomic multilocus sequencing (cgMLST) and single nucleotide polymorphism (SNP); polymyxin resistance genes were determined by PCR and sequencing. Results:b> All PR-CRKP strains were KPC-2 producing ST11 types. cgMLST results showed that the evolutionary distance between the PR-CRKP strains and Klebsiella pneumoniae in mainland China was 66.44 on average, which is more closely related than foreign strains; the 23 PR-CRKP strains were divided into 3 main subclusters based on SNP phylogenetic trees, with some aggregation among Clade 2-1 in the isolation department and date. The two-component negative regulatory gene mgrB has seven mutation types including point mutations, different insertion fragments and different insertion positions. Conclusion:b> The close affinity of PR-CRKP strains indicate the possibility of nosocomial clonal transmission and the need to strengthen surveillance of PR-CRKP strains to prevent epidemic transmission of PR-CRKP.
Humans ; Carbapenems/pharmacology* ; Anti-Bacterial Agents/therapeutic use* ; Klebsiella pneumoniae/genetics* ; Polymyxins/pharmacology* ; beta-Lactamases ; Phylogeny ; Retrospective Studies ; Multilocus Sequence Typing ; Microbial Sensitivity Tests