Staphylococcus aureus causes a broad range of life-threatening diseases in humans. This bacterium produces a large number of extracellular virulence factors that are closely associated with specific diseases which are controlled by quorum sensing. In this study, we show that azithromycin was active against methicillin-resistant Staphylococcus aureus (MRSA) strains with MICs ranged from 32 to 64 lg/mL. Azithromycin at subinhibitory concentration, markedly reduced the production of a-hemolysin at (1/16MIC, 1/8MIC) and biofilm formation at (1/16MIC, 1/8MIC), respectively. The results indicated that sub-inhibitory concentrations of azithromycin decreased the production of a-hemolysin and biofilm formation in MRSA in a dose-dependent manner. Therefore, azithromycin may be useful in the treatment of a-hemolysin producing and biofilm formation MRSA infections.Staphylococcus aureus is found among the normal human skin flora and it is an important pathogen of humans, causing diseases ranging from superficial skin and wound infections to severe illnesses such as septicaemia, endocarditis and toxic shock syndrome [1]. S. aureus is particularly a problem in hospitals because it spreads easily in these environments and causes potentially fatal infections in immunocompromised hospital patients. S. aureus cause disease through the production of virulence factors. These factors include adhesins, exotoxins, enterotoxins, hemolysins, and leukocidin, as well as proteases that enable the bacteria to spread within the host [2,3]. Quorum sensing (QS) regulates expression of genes encoding these virulence factors and biofilm formation. Strains defective in their ability to form a biofilm or produce toxins show diminished virulence [4], suggesting that a novel approach for therapy development would be to interfere with the production of virulence factors [5][6][7]. Azithromycin (AZM) is one of the macrolides antibiotics, and it is a broad-spectrum macrolide antibiotic effective against Gram-positive, Gram-negative, and atypical bacteria and has anti-inflammatory characteristics [8]. The purpose of this study is to assess the effect of azithromycin, used as a quorum-sensing inhibitor, for decrease the production of QS associated virulence factors and biofilm formation in Staphylococcus aureus.Two different clinical bacterial strains of methicillinresistant Staphylococcus aureus (MRSA) 10 and 21 were collected from different patients hospitalized at Lishui People's Hospital, Zhejiang province. S. aureus strains was identified biochemically from routinely obtained specimens by means of the Vitek ATB Expression System, version 2.7.8 (BioMe'rieux Deutschland GmbH, Nürtin-gen, Germany), which uses 32 biochemical reactions. Bacterial isolates were stored as suspensions in LB medium containing 12.5 % (vol/vol) glycerol at -70°C until tests were performed. S. aureus MRSA 10, 21 single colony was inoculated into LB media and cultured overnight at 37. Overnight culture was subcultured (1:100) into test tubes with fresh LB medium in tripl...

Pseudomonas aeruginosa produces multiple virulence factors that have been associated with quorum sensing. The aim of this study was to evaluate the prevalence of drug resistant profiles and quorum sensing related virulence factors. Pseudomonas aeruginosa were collected from different patients hospitalized in China, the isolates were tested for their susceptibility to different common antimicrobial drugs and detected QS-related virulence factors. We identified 170 isolates displaying impaired phenotypic activity, approximately 80 % of the isolates were found to exhibit the QS-dependent phenotypes, among them, 12 isolates were defective in AHLs production, and therefore considered QS-deficient strains. Resistance was most often observed to Cefazolin (81.2 %), followed by trimethoprim-sulfamethoxazole (73.5 %), ceftriaxone (62.4 %) and Cefotaxime, Levofloxacin, Ciprofloxacin (58.8 %), and to a lesser extent Meropenem (20.0 %), Cefepime (18.8 %), and Cefoperazone/sulbactam (2.4 %) The QS-deficient isolates that were negative for virulence factor production were generally less susceptible to the antimicrobials. The results showed a high incidences of antibiotic resistance and virulence properties in P. aeruginosa, and indicate that the clinical use of QS-inhibitory drugs that appear superior to conventional antimicrobials by not exerting any selective pressure on resistant strains.

No abstract

AbstractThe aim of this meta-analysis was to evaluate the clinical efficacy and safety of tripterygium glycosides in treatment of stage IV diabetic nephropathy. Methods Through searching the PubMed and CNKI databases, the open published clinically controlled trials related to efficacy and safety of tripterygium glycosides in the treatment of stage IV diabetic nephropathy were collected. The pooled total efficacy, 24h urinary protein, serum creatinine and tripterygium glycosides related toxicity were calculated using Stata 11.0 software. Results Fourteen publications including 992 subjects (512 in the experimental group and 480 in the control group) were included in this study. Eight studies reported the total clinical efficacy comparing the experiment and control groups. No significant statistical heterogeneity was found in total efficacy (I2=24.9%, p>0.05). Thus, the combined odds ratio (OR) was pooled by fixed effect model. The pooled OR=4.16 with its 95% CI 2.71~6.37 (p<0.05), which indicated the total efficacy in the experiment group, was significant higher than that of control group (p<0.05); Thirteen studies reported the post-treatment 24h urinary protein value. Statistical heterogeneity analysis indicated significant heterogeneity across studies (I2=91.1%, p<0.05); that data was pooled by a random effects model. The combined standardized mean difference (SMD) was -1.55 with its 95% I -2.06~1.03, (p<0.05). The results indicated that post-treatment 24h urinary protein in the experiment group was significant lower than that in control group (p<0.05); Ten studies reported the post-treatment serum creatinine. Significant heterogeneity existed across those studies (I2=82.3%, p<0.05). Thereafter, the data was pooled by a random effect model. The combined standardized mean difference (SMD) was −0.24 with its 95%CI −0.40~0.09, (p<0.05). The results indicated that the post-treatment serum creatinine in experiment group was significant lower than that of control group (p<0.05); Eight studies reported tripterygium glycoside-associated toxicity such as liver function damage, gastrointestinal reactions and menstrual disorders. With no statistical heterogeneity among the studies, the data was pooled by fixed effect model. The pooled OR=6.42 (95%CI 2.23~18.48, p<0.05). The pooled results showed the tripterygium glycoside- associated toxicity incidence rate was significant higher in the experiment group than that of the control group (p<0.05); There were no publication bias for effect size of total efficacy, 24h urinary protein, and serum creatinine. However, for tripterygium glycoside-related toxicity, the publication bias was significant (t=-3.55, p<0.05). Conclusion The present evidence shows that tripterygium glycosides can improve clinical efficacy, reduce the 24h urinary protein and serum creatinine, but that they increase the tripterygium glycoside-related toxicity in treatment of stage IV diabetic nephropathy.