Clinical Efficacy, Antibiotic Resistance Genes, Virulence Factors and Outcome of Hospital-Acquired Pneumonia Induced by Klebsiella pneumoniae Carbapenemase 2-Producing with Tigecycline Treatment in the ICU.

Purpose: Tigecycline is an agent for carbapenemase-producing Klebsiella pneumonia (KPC-KP), given its penetration into lung tissues. Our study focused on the molecular and clinical efficacy of tigecycline for hospital-acquired pneumonia (HAP) in the ICU. Patients and Methods: A retrospective cohort study of 52 adult KPC-KP HAP patients by searching hospital medical records from January 2018 to December 2020 was established to investigate the epidemiology of KPC-KP infections for tigecycline treatment and the associated clinical efficacy of tigecycline. The KPC-KP isolates underwent multilocus sequence typing. Molecular typing, antimicrobial resistance, and virulence profiling were also analyzed by whole-genome sequencing of KPC-KP. Results: Among 52 patients with KPC-KP, the ICU mortality rate was 14/52 (27%), and there was no significant statistical difference in mortality between the effective group and failure group (p = 0.754). However, the duration of tigecycline was statistically different between the two groups of patients (14.4 vs 10 days, p=0.046). The total bacterial clearance rate was 6/52 (11.5%). There was no significant statistical difference in both groups (p=0.416). Antibiotic resistance genes (aac3iia) and virulence gene (AREO-iutA, Capsule-wzc) were negatively correlated with clinical efficacy (p = 0.011, OR = 1.237). Conclusions: Blakpc was the main carbapenemase in all K. pneumoniae strains. ST11-KL64 KPC-KP was the most common virulence factors in KPC-KP isolates. This study suggested that antibiotic resistance genes (aac3iia) and virulence gene (AREO-iutA, Capsule-wzc) were independent mortality risk factors for patients with Klebsiella pneumoniae carbapenemase-2 producing K. pneumoniae infections, when during the tigecycline treatment. Molecular analysis of K. pneumoniae may provide an option when choosing the antimicrobial treatment.

Voltage-Gated Membranes Incorporating Cucurbit[n]uril Molecular Containers for Molecular Nanofiltration.

Smart voltage-gated nanofiltration membranes have enormous potential for on-demand and precise separation of similar molecules, which is an essential element of sustainable water purification and resource recovery. However, the existing voltage-gated membranes are hampered by limited selectivity, stability, and scalability due to electroactive monomer dimerization. Here, for the first time, the host-guest recognition properties of cucurbit[7]uril (CB[7]) are used to protect the viologen derivatives and promote their assembly into the membrane by interfacial polymerization. Viologen functions as a voltage switch, whereas CB[7] complexation prevents its dimerization and improves its redox stability. The inhibited diffusion of the CB[7]-viologen complex enables the precise patterning of the surface structure. The resultant voltage-gated membrane displays 80% improved rejection performance, excellent recovery accuracy for similar molecules, and anti-fouling properties. This work not only provides an innovative strategy for the preparation of voltage-gated smart nanofiltration membranes but also opens up new avenues for ion-selective transmission in water treatment, bionic ion channels, and energy conversion.

Vaginal microbiome analysis of healthy women during different periods of gestation.

To assess the vaginal microbiome throughout full-term uncomplicated pregnancy, a longitudinal study was designed for 12 healthy women who had prepared to become pregnant and then delivered at term (38-42 weeks) without complications. The vaginal microbial community was studied at pre-pregnancy, 8-12, 24-28, 37-38 weeks of gestation, and puerperium, using hypervariable tag sequencing of the V3-V4 region of the 16S rRNA gene. Sequencing produced approximately 10 million reads on the Illumina MiSeq. Members of the Firmicutes phyla were prevailing before and during pregnancy periods, and the proportion was quite as Proteobacteria until puerperium. Lactobacillus genus was abundant before and during pregnancy, but post-delivery vaginal microflora variety turned diverse. The species-level analysis revealed that a healthy vaginal microbiome before or during pregnancy was prominently dominated by Lactobacillus crispatus. Furthermore, PCoA analysis revealed for differences in the bacterial community composition between the two levels of Lactobacillus species in pre-pregnancy and pregnancy period (PC1 contribution of 58.46%, PC3 contribution of 8.64%). Based on the taxonomic and PCoA analysis, we found that L. crispatus was dominant in the vaginal microflora of healthy women before or during pregnancy, but at the puerperium, the status changed leading to decreased abundance of protective Lactobacillus species that made vaginal micro-ecological barrier vulnerable to diseases. Additionally, vaginal pH was an important environmental property affecting the vaginal microbial community.

Clinical and microbiological characteristics of Cryptococcus gattii isolated from 7 hospitals in China.

BACKGROUND: Infection, even outbreak, caused by Cryptococcus gattii (C. gattii) has been reported in Canada and the United States, but there were sparsely-reported cases of C. gattii in China. Our interest in occurrence, clinical manifestation, laboratory identification and molecular characterization of Chinese C. gattii strains leads us to this research. RESULTS: Out of 254 clinical isolates, initially identified as Cryptococcus neoformans (C. neoformans), eight strains were re-identified as C. gattii. Multi-locus sequence typing (MLST) showed genotype VGI accounted for the most (6 / 8), the other two strains were genotype VGII (VGIIa and VGIIb respectively) with 3 specific spectra of molecular weight about 4342, 8686, 9611 Da by MALDI-TOF MS. The minimal inhibitory concentrations (MICs) of Fluconazole with Yeast one was 2~4 times higher than that with ATB fungus 3 and MICs of antifungal agents against VGII strains were higher than against VGI strains. Comparative proteome analysis showed that 329 and 180 proteins were highly expressed by C. gattii VGI and VGII respectively. The enrichment of differentially expressed proteins was directed to Golgi complex. CONCLUSIONS: Infection by C. gattii in China occurred sparsely. Genotype VGI was predominant but VGII was more resistant to antifungal agents. There was significant difference in protein expression profile between isolates of VGI and VGII C. gattii.

Susceptibility patterns and molecular epidemiology of multidrug-resistant Acinetobacter baumannii strains from three military hospitals in China.

To date, little has been reported on the susceptibility patterns and molecular characterisation of multidrug-resistant Acinetobacter baumannii (MDRAB) clinical isolates from different Chinese military hospitals. In this study, 49 MDRAB strains were collected from three military hospitals during 2007. The minimum inhibitory concentrations (MICs) of 13 antibiotics were determined for each strain. Genotyping and dendrogram analysis of MDRAB strains were performed using the repetitive sequence-based polymerase chain reaction (rep-PCR) DiversiLab Microbial Typing System. PCR screening was carried out to investigate the distribution of various genes contributing to each resistance phenotype in the main clonal types. The rates of resistance to the majority of antibiotics tested varied between 75.5% and 100%, with the exception of polymyxin B. Two DiversiLab rep-PCR clones (A and B) were widespread in three hospitals in different cities, one clone (D) existed only in two hospitals located in the same city (Beijing), and the other two clones (C and E) were present in only one hospital. In addition, this study shows a high distribution of intI1, ISAba1, bla(OXA-23), bla(ADC), adeB, adeJ, abeM and tet(B) genes, which mediate resistance to structurally unrelated antimicrobials in MDRAB isolates. These results suggest that all isolates were resistant to at least three classes of antibiotics. In addition, clonal dissemination among the three hospitals located in two different cities in China, previously documented in many regions of Europe and Asia-Pacific nations, emphasises the epidemic potential of these MDRAB isolates.

[Study on the molecular characteristics of multidrug-resistant Acinetobacter baumannii].

OBJECTIVE: To investigate antibiotic resistance, carbapenemase genotype and the molecular epidemiology of multidrug-resistant Acinetobacter baumannii (Aba) collected from 3 military hospitals in China. METHODS: The minimum inhibitory concentrations (MIC) were examined by ager dilution method. Genotypes of carbapenemases were amplified by multiplex PCR and its products were sequenced. PCR was used to detect per gene. Homology of the resistant isolates was analyzed by pulse-field gel electrophoresis (PFGE). RESULTS: Among the 64 MDRA strains, 78.1% (50) strains possessed bla(OXA-23) gene, 89.1% (57) carried Class 1 integrase gene, 39.1% (25) with bla(PER-1) gene, and 1 strain with bla(OXA-58-like) gene. PFGE showed that 13 (A, B, C, D, E genotype) different clones were identified in these strains. A, B, and U clones were the predominant clones in three hospitals, respectitively. CONCLUSION: Outbreaks of multidrug-resistant Aba occurred at 3 military hospitals with the most prevalent carbapenemase as OXA-23 enzyme. OXA-58 type of carbapenemase and per-1 in Aba were also isolated.

[Transmission and molecular characteristics of carbapenem-resistant Acinetobacter baumannii].

OBJECTIVE: To study the mode of transmission and molecular characteristics on carbapenem-resistant Acinetobacter baumannii strain. Strains were isolated from different parts of samples in various patients. METHODS: Clinical information of carbapenem-resistant Acinetobacter baumannii isolates were stored and analyzed by WHONET 5.4 software. The transmission and pathopoiesis of the strains were learned through case file review. Genotypes of isolates were identified by pulse-field gel electrophoresis (PFGE) and genes of carbapenemase were detected by multiple PCR, in order to find molecular characteristics and relatedness between strains. RESULTS: 29 stains of Acinetobacter baumannii resistant to carbapenem were isolated from 2 or more kinds of samples among 13 patients'. Two genotypes were identified by PFGE: genotype A was obtained from 22 isolates in 11 patients and genotype B was obtained from 7 isolates in 4 patients. PCR amplification showed that all strains possessed OXA-23 gene except 1, and all strains possessed Integrase gene I except 3. CONCLUSION: There were 2 different genotypes from 29 strains of carbapenem-resistant Acinetobacter baumannii with Genotype A as the main type. OXA-23 carbapenemase gene and integrase gene I were detected from most of the isolates. All the strains could be easily transmitted in the body of the patients and among patients, hence becoming the epidemic pathogen of iatrogenic infection.