Effect of chlorogenic acid on the quorum-sensing system of clinically isolated multidrug-resistant Pseudomonas aeruginosa.

AIMS: Quorum sensing (QS) is the intercellular communication used by bacteria to regulate collective behaviour. QS regulates the production of virulence factors in many bacterial species and is considered to be an attractive target for reducing bacterial pathogenicity. Chlorogenic acid (CA) is abundant in vegetables, fruits, and traditional Chinese medicine, and has multiple activities. This study aimed to investigate the QS quenching activity of CA against clinically isolated multidrug-resistant Pseudomonas aeruginosa. METHODS AND RESULTS: The results showed that CA inhibited the mobility of bacteria, reduced the production of pyocyanin, and inhibited the activity of elastase. Furthermore, crystal violet staining and scanning electron microscope experiments showed that CA inhibited the formation of multidrug-resistant P. aeruginosa biofilm. CA at or below the concentration of 2560 µg/mL exerted negligible cytotoxicity to RAW264.7 cells. The study also examined the expression of QS-related genes, including lasI, lasR, rhlI, rhlR, pqsA, and pqsR in P. aeruginosa and found that the expression of these genes was down-regulated under CA treatment. CONCLUSIONS: The study showed that CA could be used as an anti-virulence factor for treating clinical P. aeruginosa infection. SIGNIFICANCE AND IMPACT OF STUDY: For the first time, this study took clinically isolated multidrug-resistant P. aeruginosa as the experimental object, and suggested that CA might be an effective antimicrobial compound targeting QS in treating P. aeruginosa infection, thus providing a new therapeutic direction for treating bacterial infection and effectively alleviating bacterial resistance.

Antibacterial and Anti-biofilm Efficacy of Chinese Dragon's Blood Against Staphylococcus aureus Isolated From Infected Wounds.

Chinese dragon's blood (CDB), a characteristic red resin, is an important traditional Chinese medicine (TCM), and empiric therapy of infected wounds with CDB is performed in clinical settings. For the first time, we herein report the antibacterial and anti-biofilm efficacy of CDB against Staphylococcus aureus (S. aureus). Antimicrobial susceptibility testing, growth curve assay, time-kill curve assay, crystal violet biofilm assay, scanning electron microscope (SEM) analysis, cell membrane tests, and quantitative real-time polymerase chain reaction (qRT-PCR) were used for this purpose. The results suggested that the minimum inhibitory concentration (MIC) values of CDB against S. aureus ranged from 32 to 128 µg/mL. Growth curves and time-kill curves confirmed that CDB could inhibit the growth of S. aureus. The biofilm formation ability and the expression levels of saeR, saeS, and hla of S. aureus in the presence and absence of CDB were statistically significant (P < 0.01). The results of SEM analysis and cell membrane tests revealed that exposure to CDB had some destructive effects on S. aureus cells. In conclusion, CDB exhibits positive antibacterial activity against S. aureus. Moreover, CDB could reduce the biofilm formation and the virulence factors of S. aureus by downregulating the expression levels of saeR, saeS, and hla genes. These findings indicated that CDB has immense potential to serve as a viable alternative for the treatment of infected wounds caused by S. aureus in clinical settings.

Bloodstream infections caused by ST2 Acinetobacter baumannii: risk factors, antibiotic regimens, and virulence over 6 years period in China.

BACKGROUND: Bloodstream infection (BSI) caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) has been increasingly observed among hospitalized patients. The following study analyzed the epidemiology and microbiological characteristics of MDR-AB, as well as the clinical features, antimicrobial treatments, and outcomes in patients over a six years period in China. METHODS: This retrospective study was conducted in a large tertiary hospital in China between January 2013 and December 2018. The clinical and microbiological data of all consecutive hospitalized patients with MDR-AB induced bloodstream infection were included and analyzed. RESULTS: A total of 108 BSI episodes were analyzed. All MDR isolates belonged to ST2, a sequence type that has spread all over the world. Overall, ST2 strains showed strong biofilm formation ability, high serum resistance, and high pathogenicity. As for the clinical characteristics of the patient, 30-day mortality was 69.4% (75/108). The three main risk factors included mechanical ventilation, intensive care unit (ICU) stay, and thrombocytopenia; three protective factors included a change of antimicrobial regimen within 48 h after positive blood culture, use of the antibacterial agent combination, and more inpatient days. The most effective antibacterial regimen was the combination of cefoperazone/sulbactam and tigecycline. CONCLUSIONS: BSI caused by ST2 A.baumannii represents a difficult challenge for physicians, considering the high mortality associated with this infection. The combination of cefoperazone/sulbactam and tigecycline may be an effective treatment option.

Protective roles of Pyracantha fortuneana extract on acute renal toxicity induced by cadmium chloride in rats.

PURPOSE: To investigate the protective roles of pyracantha fortune fruit extract (PFE) on acute renal toxicity induced by cadmium chloride (CdCl2) in rats. METHODS: Rats were pretreated with PFE and consecutively injected with CdCl2 (6.5 mg/kg) for 5 days. RESULTS: The concentration of Cd, kidney weight, malondialdehyde (MDA), and nitric oxide (NO) production were remarkably increased in CdCl2 group as well as the levels of plasma uric acid, urea, and creatinine (P < 0.001). However, the body weight and glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione peroxidase (GR) levels were markedly reduced by CdCl2 treatment (P < 0.001). Histological manifestations of renal tissue showed severely adverse changes. Moreover, CdCl2 treatment significantly decreased the B-cell lymphoma-2 (Bcl-2) expression while increased the Bcl-2-Associated X Protein (Bax), tumor necrosis factor-α (TNF-α) expression (P < 0.001). Additionally, the expression of Nrf2/Keap 1 related proteins Keap-1 gained a significant increase (P < 0.001), whereas the Nrf2, HO-1, γ-GCS, GSH-Px and NQO1 expression decreased by CdCl2 treatment (P < 0.05). These rats were pretreated with PFE to improve the changes caused by CdCl2 treatment. CONCLUSION: PFE could protect the kidney against acute renal toxicity induced by CdCl2.

Protective roles of Pyracantha fortuneana extract on acute renal toxicity induced by cadmium chloride in rats

Abstract Purpose: To investigate the protective roles of pyracantha fortune fruit extract (PFE) on acute renal toxicity induced by cadmium chloride (CdCl2) in rats. Methods: Rats were pretreated with PFE and consecutively injected with CdCl2 (6.5 mg/kg) for 5 days. Results: The concentration of Cd, kidney weight, malondialdehyde (MDA), and nitric oxide (NO) production were remarkably increased in CdCl2 group as well as the levels of plasma uric acid, urea, and creatinine (P < 0.001). However, the body weight and glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione peroxidase (GR) levels were markedly reduced by CdCl2 treatment (P < 0.001). Histological manifestations of renal tissue showed severely adverse changes. Moreover, CdCl2 treatment significantly decreased the B-cell lymphoma-2 (Bcl-2) expression while increased the Bcl-2-Associated X Protein (Bax), tumor necrosis factor-α (TNF-α) expression (P < 0.001). Additionally, the expression of Nrf2/Keap 1 related proteins Keap-1 gained a significant increase (P < 0.001), whereas the Nrf2, HO-1, γ-GCS, GSH-Px and NQO1 expression decreased by CdCl2 treatment (P < 0.05). These rats were pretreated with PFE to improve the changes caused by CdCl2 treatment. Conclusion: PFE could protect the kidney against acute renal toxicity induced by CdCl2.