Background: The emergence of multidrug resistance (MDR) and extensively drug-resistance (XDR) of Klebsiella pneumoniae strain has brought great threaten to traditional antibiotics. Previous studies showed that plant-derived avonoids have inhibitory functions on pathogens. However, In K. pneumoniae, the antibacterial activities of different avonoids on the growth and bio lm formation remains a mystery. The aim of the present study is to evaluate the antioxidant abilities of different avonoids and to identify their inhibitory effects on K. pneumoniae growth and bio lm formation.Results: Totally 10 avonoids representing 4 major categories were screened and used in this study. The antioxidant capacity of each avonoid was evaluated through a DPPH assay. Rutin showed highest free radical scavenging capacity, followed by kaempferol, luteolin, quercetin, apigenin, hesperidin, sinensetin, naringenin, naringin and 3,5,6,7,8,3',4'-heptamethoxy avone. The inhibitory effect of rutin and naringin on bacteria growth were compared. The antibacterial activity of avonoid is highly correlated with the antioxidant capacity. Among these avonoids, rutin showed the best inhibitory capacity against both the growth curve and bio lm production. The lowest value of MIC was found in rutin against K. pneumoniae ATCC700603 (1024μg/mL) and E.coli ATCC25922 (512μg/mL). The MBIC were not found. The expression pro les of 15 genes were analyzed in bio lm cells both with and without rutin treatment. The correlation analysis showed the mrkA gene expression was positively correlated with the bio lm biomass accumulation.Conclusions: Our study indicated that avonols showed stronger antibacterial activities. The bio lm production is correlated with several gene expression rather than one. Rutin is a potential agent to inhibit the K. pneumoniae bio lm formation.

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.

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 csuDpositive 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.

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 -IS kpn8-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 β-lactams and β-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.

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