Objective To investigate and analyze the epidemiological characteristics and the causes of a suspected outbreak of carbapenem-resistant Acinetobacter baumannii(CRAB)infection,and provide basis for healthcare-asso-ciated infection(HAI)prevention and control.Methods Information of 3 patients with CRAB positive culture from the respiratory intensive care unit(RICU)of a hospital in May 2024 was collected.Microbiological sampling was performed in patients' ward environment,and the specimens were cultured and strains were identified.CRAB strains detected from the environment and patients were performed whole genome sequencing(WGS).Multiple de-partments jointly formulated and implemented comprehensive infection control measures,and the effectiveness were evaluated.Results CRAB was cultured from specimens of sputum and bedside office mice of 3 patients.WGS de-tection showed that ST2158 and ST1791 resistance genes were detected from both sputum and bedside office mice of 2 patients.After comprehensive assessment,2 patients were confirmed with HAI and 1 patient was confirmed with colonization,ruling out an outbreak of HAI.A total of 24 environmental specimens were taken for environmental hygiene monitoring,with a CRAB detection rate of 58.33％.CRAB detected from bedside mice and patients' spu-tum specimen had consistent CRAB drug susceptibility testing results.After implementing measures such as in-creasing the frequency of cleaning and disinfection of ward environment,strengthening the implementation of hand hygiene,and enhancing the supervision of department personnel as well as HAI prevention and control training,HAI was effectively controlled.Conclusion The possible transmission route of this suspected CRAB outbreak in RICU is the contamination of office mice,which caused healthcare workers carrying CRAB in their hands,leading to cross infection due to poor hand hygiene implementation of healthcare workers.Strengthening the cleaning and dis-infection of environmental surface and the management of hand hygiene of healthcare workers are key measures to prevent CRAB HAI.

Objective To investigate and analyze the epidemiological characteristics and the causes of a suspected outbreak of carbapenem-resistant Acinetobacter baumannii(CRAB)infection,and provide basis for healthcare-asso-ciated infection(HAI)prevention and control.Methods Information of 3 patients with CRAB positive culture from the respiratory intensive care unit(RICU)of a hospital in May 2024 was collected.Microbiological sampling was performed in patients' ward environment,and the specimens were cultured and strains were identified.CRAB strains detected from the environment and patients were performed whole genome sequencing(WGS).Multiple de-partments jointly formulated and implemented comprehensive infection control measures,and the effectiveness were evaluated.Results CRAB was cultured from specimens of sputum and bedside office mice of 3 patients.WGS de-tection showed that ST2158 and ST1791 resistance genes were detected from both sputum and bedside office mice of 2 patients.After comprehensive assessment,2 patients were confirmed with HAI and 1 patient was confirmed with colonization,ruling out an outbreak of HAI.A total of 24 environmental specimens were taken for environmental hygiene monitoring,with a CRAB detection rate of 58.33％.CRAB detected from bedside mice and patients' spu-tum specimen had consistent CRAB drug susceptibility testing results.After implementing measures such as in-creasing the frequency of cleaning and disinfection of ward environment,strengthening the implementation of hand hygiene,and enhancing the supervision of department personnel as well as HAI prevention and control training,HAI was effectively controlled.Conclusion The possible transmission route of this suspected CRAB outbreak in RICU is the contamination of office mice,which caused healthcare workers carrying CRAB in their hands,leading to cross infection due to poor hand hygiene implementation of healthcare workers.Strengthening the cleaning and dis-infection of environmental surface and the management of hand hygiene of healthcare workers are key measures to prevent CRAB HAI.

Objective:To analyze the molecular characteristics and antibiotic susceptibility of two strains of Nocardia farcinica isolated from patients with joint infection using whole genome sequencing. Methods:Two strains of Nocardia farcinica causing knee-joint infections in two elderly patients were collected in January 2020. Whole genome sequencing was used to determine the nocardia species. Drug sensitivity test was performed using the micro-broth dilution and E-test method according to CLSI M24 guideline. ABRicate was used to analyze drug resistance and virulence genes. Snippy and other bioinformatic tools were used for genomic comparison, and to construct SNP homologous tree. Results:The clinical isolates in this study were both Nocardia farcinica. Antimicrobial susceptibility test showed the isolates were resistant to ceftriaxone, cefepime, cefotaxime and trimethoprim/sulfamethoxazole (TMP/SMX). Imipenem, linezolid and amoxicillin-clavulanic acid showed good activity. Four antibiotic resistance genes including class A β-lactamase gene far-1, RNA polymerase binding protein gene RbpA, multi-drug resistance efflux pump transcription activator gene MtrA and regulatory transcription factor gene vanR-O were identified in the Nocardia farcinica genomes, which conferred resistance to beta-lactams, rifampicin, macrolides and vancomycin respectively. No acquired TMP/SMX resistance genes were identified. There are multiple missense mutations in the dihydrofolate reductase family genes. Four virulence genes of icl, mbtH, phoP,and relAthat are homologous to Mycobacterium tuberculosis were found. SNP homologous tree analysis showed the two Nocardia strains were closely related, and there were only ten SNP sites, six compound substitutions and one deletion mutation between them. Conclusions:Whole genome sequencing technology is helpful to explore the molecular characteristics and resistance mechanisms of Nocardia species. Nocardia farcinica has a trend of spreading in China. Resistance to TMP/SMX is worthy of attention. The mutation of genes involved in the metabolic pathway of dihydrofolate might be one of multiple TMP/SMX resistance mechanisms.

Objective:To analyze the molecular characteristics and antibiotic susceptibility of two strains of Nocardia farcinica isolated from patients with joint infection using whole genome sequencing. Methods:Two strains of Nocardia farcinica causing knee-joint infections in two elderly patients were collected in January 2020. Whole genome sequencing was used to determine the nocardia species. Drug sensitivity test was performed using the micro-broth dilution and E-test method according to CLSI M24 guideline. ABRicate was used to analyze drug resistance and virulence genes. Snippy and other bioinformatic tools were used for genomic comparison, and to construct SNP homologous tree. Results:The clinical isolates in this study were both Nocardia farcinica. Antimicrobial susceptibility test showed the isolates were resistant to ceftriaxone, cefepime, cefotaxime and trimethoprim/sulfamethoxazole (TMP/SMX). Imipenem, linezolid and amoxicillin-clavulanic acid showed good activity. Four antibiotic resistance genes including class A β-lactamase gene far-1, RNA polymerase binding protein gene RbpA, multi-drug resistance efflux pump transcription activator gene MtrA and regulatory transcription factor gene vanR-O were identified in the Nocardia farcinica genomes, which conferred resistance to beta-lactams, rifampicin, macrolides and vancomycin respectively. No acquired TMP/SMX resistance genes were identified. There are multiple missense mutations in the dihydrofolate reductase family genes. Four virulence genes of icl, mbtH, phoP,and relAthat are homologous to Mycobacterium tuberculosis were found. SNP homologous tree analysis showed the two Nocardia strains were closely related, and there were only ten SNP sites, six compound substitutions and one deletion mutation between them. Conclusions:Whole genome sequencing technology is helpful to explore the molecular characteristics and resistance mechanisms of Nocardia species. Nocardia farcinica has a trend of spreading in China. Resistance to TMP/SMX is worthy of attention. The mutation of genes involved in the metabolic pathway of dihydrofolate might be one of multiple TMP/SMX resistance mechanisms.

In a one-step fermentation system of vitamin C production with Gluconobacter oxydans and Ketogulonicigenium vulgare, a functional module of α-lipoic acid biosynthesis was constructed in G. oxydans. The engineered G. oxydans was co-cultured with K. vulgare to enhance the growth and 2-keto-L-gulonic acid (2-KGA) production of K. vulgare. This one-step fermentation system alleviated the growth inhibition during the mono-culture of K. vulgare and strengthened the interaction between the two bacteria. Moreover, the yield of vitamin C precursor (2-KGA) increased to 73.34 g/L (the control group was 59.09 g/L), and the conversion of D-sorbitol to 2-KGA increased to 86.0%. This study provides a new idea for further optimizing the one-step fermentation system of vitamin C production.
Ascorbic Acid ; Fermentation ; Gluconobacter oxydans ; Rhodobacteraceae ; Thioctic Acid ; biosynthesis