Glabridin Functions as a Quorum Sensing Inhibitor to Inhibit Biofilm Formation and Swarming Motility of Multidrug-Resistant Acinetobacter baumannii.

Objective: Acinetobacter baumannii is a hazardous bacterium that causes hospital-acquired nosocomial infections, and the advent of multidrug-resistant A. baumannii (MDR-AB) strains is concerning. Novel antibacterial therapeutic strategies must be developed. The biological effects of glabridin on MDR-AB were investigated in this study. Methods: The minimum inhibitory concentrations (MICs) of glabridin against eight clinical MDR-AB strains were determined using the broth microdilution technique. Crystal violet staining was used to assess biofilm development, which has significant contribution to bacterial resistance. Swarming motility was measured according to surface growth zone of MDR-AB on LB agar medium. qRT-PCR was used to evaluate the expression of quorum sensing genes abaI and abaR. Glabridin and routinely used therapeutic antimicrobial agents were tested for synergistic action using the checkerboard method. Results: According to our findings, glabridin suppressed MDR-AB growth at high doses (512-1024 µg/mL). The 1/4 MIC of glabridin significantly decreased MDR-AB biofilm formation by 19.98% (P < 0.05), inhibited MDR-AB motility by 44.27% (P < 0.05), whereas the 1/2 MIC of glabridin dramatically reduced MDR-AB biofilm development by 27.43% (P < 0.01), suppressed MDR-AB motility by 50.64% (P < 0.05). Mechanistically, glabridin substantially downregulated the expression of quorum sensing-related genes abaI and abaR by up to 39.12% (P < 0.001) and 25.19% (P < 0.01), respectively. However, no synergistic effect between glabridin and antibacterial drugs was found. Conclusion: Glabridin might be a quorum sensing inhibitor that inhibits MDR-AB biofilm development and swarming motility.

Skin and soft tissue infection caused by Cysteiniphilum litorale in an immunocompetent patient: A case report.

Cysteiniphilum litorale is a Gram-negative coccobacillus first isolated from the seawater of Wailingding Island near the estuary of Pearl River in southern China. This organism was previously not considered to cause disease in animals or humans. We report a case of a 19-year-old female patient infected with abscess caused by C. litorale in the middle digit of her right hand after minor trauma during the handling of estuarine shrimps at home. C. litorale was cultured from the wound exudate of the patient and identified by 16S rRNA gene sequencing. Whether C. litorale may be transmitted to humans via other channels requires further exploration.

Acquisition of Tigecycline Resistance by Carbapenem-Resistant Klebsiella pneumoniae Confers Collateral Hypersensitivity to Aminoglycosides.

Tigecycline is a last-resort antibiotic for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to broaden our understanding of the acquisition of collateral hypersensitivity by CRKP, as an evolutionary trade-off of developing resistance to tigecycline. Experimental induction of tigecycline resistance was conducted with tigecycline-sensitive CRKP clinical isolates. Antimicrobial susceptibility testing, microbial fitness assessment, genotypic analysis and full-genome sequencing were carried out for these clinical isolates and their resistance-induced descendants. We found that tigecycline resistance was successfully induced after exposing CRKP clinical isolates to tigecycline at gradually increased concentrations, at a minor fitness cost of bacterial cells. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) found higher expression of the efflux pump gene acrB (5.3-64.5-fold) and its regulatory gene ramA (7.4-65.8-fold) in resistance-induced strains compared to that in the tigecycline-sensitive clinical isolates. Stable hypersensitivities to aminoglycosides and other antibiotics were noticed in resistance-induced strains, showing significantly lowered MICs (X 4 - >500 times). Full genome sequencing and plasmid analysis suggested the induced collateral hypersensitivity might be multifaceted, with the loss of an antimicrobial resistance (AMR) plasmid being a possible major player. This study rationalized the sequential combination of tigecycline with aminoglycosides for the treatment of CRKP infections.

[A gene related to inhibition of sperm mobility in Staphylococcus aureus from the sperm of infertile men].

OBJECTIVE: To analyze the whole genome sequences of Staphylococcus aureus strains from the sperm of infertile males and identify the gene which may induce the inhibition of sperm motility (ISM). METHODS: Twenty-two Staphylococcus aureus strains were isolated from the sperm of infertile males in the First Hospital Affiliated to Wenzhou Medical University and, according to the ability of ISM, divided into an ISM and a non-ISM group. Two strains most representative of the biological function of each group were selected, namely MJ015 from the ISM and MJ163 from the non-ISM group, and DNA extracted from them for whole genome sequencing. The data obtained were subjected to whole-genome sequence assembly and submitted to NCBI for annotation, with the accession number of CP038183 for MJ015 and CP038229 for MJ163. The whole genome sequences of MJ015 and MJ163 were compared in full detail using BRIG and Artemis software suite to identify the target gene. RESULTS: The whole genome sequence of MJ015 was 2 784 836 bp in length, containing 2 plasmids, and that of MJ163 was 2 746 673, containing 1 plasmid, each with a 32.13%, 32.08% content of guanine-cytosine (GC), and annotated with 2 921 and 2 844 genes respectively. Comparison between the whole genome sequences of MJ015 and MJ163 revealed an almost 130 kb gap, in which a gene named sak was found to express a potential serum inhibition factor, whose transcription product was proved to be a differentially expressed protein in the two strains. CONCLUSIONS: The gene sak in MJ015 may play a key role in the inhibition of sperm mobility, but the inhibition intensity of its transcription product staphylococcus kinase has to be further studied.

Investigation of mechanisms and molecular epidemiology of linezolid nonsusceptible Enterococcus faecalis isolated from a teaching hospital in China.

The epidemiological and molecular characteristics of eight linezolid nonsusceptible Enterococcus faecalis isolated from a teaching hospital in China (January to July 2014) were investigated. The target site modifications and cfr gene associated with linezolid resistance were not found. Results of the epidemiological investigation indicated that linezolid resistance possibly occurred on several independent occasions and was often not related to linezolid administration.

[Study on the Effects of Ginsenoside Rb1 on DPPC Bilayers by Using Thermo-Raman Spectrum and DSC].

The research on the interactions between Ginsenosides and biomembranes plays a crucial role in thorough understanding the pharmacological activity and biologyical effect of Chinese medicine Panax ginseng. With the bilayer structure, DPPC often serves as an simulation model of the cell membrane to study the role of drug molecules and cell membranes. Ginsenoside Rb1, one of the most important components of Panaxginseng, playing the significant roles of pharmacological effects and biological properties. Raman and differential scanning calorimetry (DSC) are respectively a powerful tool for discussing the molecular interaction, and a kind of general technology by which researching the bilayer monomer structures and its interactions with drug molecules. However, rarely research reports on the interactions between drug molecules and biomembranes by means of both technologies above. In this paper, the influence of ginsenoside monomer Rb1 on DPPC membrane bilayers was investigated by thermo-Raman and DSC. In Raman spectra, the changes of DPPC molecule have been observed before and after interacted with ginsenoside Rb1, the data analysis indicates three aspects: the O-C-C-N+ polar head group skeleton, C-C stretching vibration area, and the C-H bond stretching vibrarion in terminated methyl group of alkyl chains. The results showed that ginsenoside Rb1 molecule with certain concentration has not changed the gauche conformation of the polar head backbone group in DPPC bilayers, the order of the internal molecular chain and the lateral chain-chain packing have been decreased as the temperature increased, the lateral disposed disorder has been increased. The changes of some thermodynamic constants obtained by DSC experiment such as phase transition temperature (Tm), the temperature at which the transition is half completed (ΔT1/2), and the transition enthalpy normalized per mol of DPPC (AH) have been showed further results of the thermo Raman experiments, with increasing the concentration of ginsenoside Rb1, the pre-transition temperature of DPPC bilayers dropped immediately with small amount of the Rb1 drug when the containtion was only 5 mol% and the whole system has been destructed at the same time, the main phase transition peak showed as a new little shoulder seam, however, both pre- and main transition peak disappeared completely until the drug concentration increased to 20 mol%, the phase transition temperature of DPPC has been reduced significantly, and the fluidity of bilayers has been increased. Both experiments indicated that the strong effects of ginsenoside Rb1 on DPPC.

[Spermatozoal immobilization ability and virulence genes of Staphylococcus aureus isolated from the semen of infertile men].

OBJECTIVE: To investigate the impact of Staphylococcus aureus from infertile men on sperm motility and the relationship between virulence genes and the activity of spermatozoal immobilization. METHODS: We collected 60 strains of non-repeated Staphylococcus aureus from the semen of 589 infertile males and analyzed the influence of Staphylococcus aureus on sperm motility using the computer-aided sperm analysis system. We selected the strains that apparently decreased sperm motility and detected their virulence genes by PCR. RESULTS: Sperm motility was significantly decreased in 17 of the 60 strains of Staphylococcus aureus (P < 0.05). The main virulence genes in these strains were hlg (33.3%), scn (23.3%), cna (20%), hlb (20%), and clfA (18.3%), others including icaA, fnbA, tst, seb, hld, eta and sea. The scn gene carriers accounted for 47.1% in the spermatozal immobilization positive group, significantly higher than 14% in the negative group (P < 0.05). No statistically significant differences were found in the percentages of the carriers of the other virulence genes between the two groups (P > 0.05). CONCLUSION: Infections of Staphylococcus aureus in male reproductive system can lead to the decrease of sperm motility, which may be associated with the Staphylococcus complement inhibitor encoding gene scn.

[Antimicrobial resistance characteristics of and disinfectant-resistant gene distribution in Staphylococcus aureus isolates from male urogenital tract infection].

OBJECTIVE: To study the antibiotic- and disinfectant-resistance features of and disinfectant-resistant gene distribution in Staphylococcus aureus (Sa) isolated from the urogenital tract of male patients with urogenital tract infection (UTI). total of 152 Sa isolates were collected from the urethral discharge specimens from male UTI patients. The minimum inhibition concentration (MIC) of antimicrobial agents and disinfectants commonly used against Sa were tested by standard ager dilution; the methicillin-resistant Sa (MRSA) isolates detected by cefoxitin disk diffusion and mecA gene amplification; Staphylococcal cassette chromosome mec (SCCmec) genotyping performed by multiplex PCR; the disinfectants gene qac (quaternary ammonium compound) amplified by PCR; and the clonal relatedness of qacA/B-positive MRSA isolates investigated by pulsed-field gel electrophoresis (PFGE). RESULTS: Out of the 152 Sa isolates, 91 (59.9%) were found to be MRSA. SCCmec genotyping showed SCCmec V to be the main type, accounting for 63.7% (58/91), with 8 (8.8%) isolates of SCCmec I, 2 (2.2%) isolates of SCCmec II, 19 (20.9%) isolates of SCCmec III, and 4 (4. 4%) isolates of SCCmec IV. The Sa isolates exhibited high rates of non-susceptibility to penicillin (95.4%) , erythromycin (72.4% ) , ciprofloxacin (42. 8%), and levofloxacin (44.7%), and a fairly high sensitivity to nitrofurantoin, teicoplanin, linezolid, and vancomycin. The MIC in the Sa isolates was 0. 25 -16 microg/ml for chlorhexidine; MIC50 and MIC90 were 2.0 and 4.0 microg/ml respectively for MRSA strains and both 1.0 microg/ml for MSSA strains. Out of the 152 Sa isolates, 72 (47.4%) harbored the qacA/B gene, 6 (3.9%) the smar (qacC + qacD) gene, 9 (5.9%) the qacE delta 1 gene, and 2 (1.3%) the qacH gene, but no qacG and qacJ genes were detected. PFGE analysis showed that the qacA/B-positive MRSA isolates were distributed CONCLUSION: Clinical Sa isolates exhibited varied degrees of resistance to commonly used antibiotics, and in a polyclonal manner. some showed a robust tolerance to chlorhexidine. The main disinfectant-resistant gene is qacA/B. Antimicrobial agents and disinfectants should be used rationally according to clinicians.

Isolation of both Pseudozyma aphidis and Nocardia otitidiscaviarum from a mycetoma on the leg.

We describe a case of mycetoma which typified the classic presentation of the disease: a male farmer with affection of the lower limbs and a history of trauma. The patient presented with a swollen right lower limb showing multiple discharging sinuses for 25 years. Histopathologically, grains were found by HE stain, and clustered yeast-like cells were observed by PAS stain. The distinctive 'dot-in-circle' sign was found through MRI. Besides Nocardia otitidiscaviarum, Pseudozyma aphidis was isolated from deep tissue culture, and the identification of the etiologic species was ascertained by DNA sequencing. Generally speaking, Nocardia otitidiscaviarum is an infrequent cause of mycetoma, and Pseudozyma species are usually isolated from plant material rather than clinical specimens. This is the first case of mycetoma from which both Nocardia otitidiscaviarum and Pseudozyma aphidis were isolated.

Prevalence of plasmid-mediated quinolone resistance in Escherichia coli isolates in Wenzhou, Southern China, 2002-2008.

A total of 514 consecutive clinical Escherichia coli isolates, irrespective of resistance background, were collected in the period 2002-2008 in Wenzhou, southern China, to investigate the prevalence of plasmid-mediated quinolone resistance (PMQR). The dominant PMQR gene was aac(6')-Ib-cr, followed by qnr, whereas qepA was absent. A total of 253 (49.2%) of these isolates were aac(6')-Ib-positive. Subsequently, 134 of these isolates were sequenced and 42 (31.3%) found to harbor aac(6')-Ib-cr, 18 to harbor new aac(6')-Ib mutants, and 74 to harbor wild-type aac(6')-Ib. The genes qnrA, qnrB, and qnrS were found in 2 (0.4%), 6 (1.2%), and 14 (2.7%) of 514 isolates, respectively, with 2 isolates co-harboring qnrB and qnrS genes. Sequencing allowed us to identify qnrA1, qnrB4, qnrB6, and qnrS1 in 20 qnr-positive isolates, with qnrS1 being the most prevalent allele. The genes qnrC and qnrD were not found in any isolates. Interestingly, 35% of qnr-positive isolates and 16.7% of aac(6')-Ib-cr-positive isolates were susceptible to ciprofloxacin. PMQR genes are therefore present in both quinolone-resistant and -susceptible isolates and can also be transferred by conjugation experiments, thus suggesting a likely future increase in quinolone resistance.

Effect of antimicrobial agents on the toll-like receptors and inflammatory cytokines in liver tissue of the alcohol-induced liver disease in rats with Vibrio vulnificus sepsis.

BACKGROUND: Septicemia and inflammation-mediated septic shock caused by Vibrio vulnificus (VV) is strongly associated with chronic liver disease. This study examined the effects of antimicrobial therapy on expression of hepatic toll-like receptors and inflammatory cytokines in rats with alcohol-induced liver disease complicated by VV sepsis. METHODS: Male Sprague-Dawley rats were assigned to the following treatment groups: normal control (N), alcoholic liver disease control (A), antimicrobial-treated alcoholic liver disease control (AA), alcoholic liver disease with VV sepsis (AV), and antimicrobial-treated alcoholic liver disease with VV sepsis (AVA). Alcohol-induced liver disease was observed in all groups except N. Expression of mRNAs encoding hepatic toll-like receptors 2 and 4, myeloid differentiation protein-2, tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6 and IL-10 was determined by RT-PCR. RESULTS: mRNAs encoding toll-like receptors 2 and 4 and myeloid differentiation protein-2 were significantly up-regulated in group AV as compared to control groups at 2 - 24 hours of sepsis; peak expression occurred at 12 hours. These mRNAs were also up-regulated in group AVA but to lesser degrees than in group AV at comparable time post-infection. mRNAs encoding TNF-alpha, IL-1beta and IL-6 were significantly elevated in group AV as a function of infection. In group AVA as compared to AV, expression of TNF-alpha and IL-1beta mRNAs was lower at 12 - 24 hours post-infection and expression of IL-6 mRNA was lower at 24 hours post-infection. Compared with control groups, IL-10 mRNA expression in group AV was markedly higher at 12 - 24 hours of sepsis. Expression of IL-10 mRNA was lower in group AVA as compared to AV at 24 hours of sepsis. CONCLUSIONS: Antimicrobial therapy reduces expression of toll-like receptors and cytokines in rats with alcohol-induced liver disease complicated by VV sepsis. Monitoring hepatic toll-like receptor and cytokine expression during antibiotic therapy may be valuable for determining the course of VV sepsis in subjects with liver disease.

[Effects of antimicrobial agents on the Toll like receptors and myeloid differentiation protein-2 in liver tissue of alcohol-induced liver disease: experiment with rats].

OBJECTIVE: To investigate the effects of antimicrobial agents on the Toll like receptors (TLRs) and myeloid differentiation protein (MD)-2 in liver tissue of alcohol-induced liver disease with Vibrio vulnificus (VV) sepsis. METHODS: Eighty SD rats were randomly divided into 2 groups: alcohol gastric lavage group (n = 74) undergoing alcohol gastric perfusion once a day for 10 weeks and normal control group (Group N, n = 6). 66 surviving rats in the gastric perfusion group were randomly divided into 6 equal subgroups: Subgroup A was alcohol-induced liver disease control subgroup. Subgroup AA, alcohol-induced liver disease and antibacterial drug control subgroup, underwent intraperitoneal injection of cefoperazone sodium and levofloxacin (LVFX). The other 9 subgroups underwent subcutaneous injection of VV to establish animal model of VV sepsis, the rats of 4 of which were killed 2, 6, 12, and 24 h later respectively with their livers taken out (Subgroups AV), and the rats of 5 of which underwent intraperitoneal injection of cefoperazone sodium and LVFX 4 h after VV injection twice a day (Subgroups AVA) and were killed 6, 12 , 24 , 36 h, and 1 week later with their livers taken out. The behavioral changed were observed. PCR was used to detect the mRNA expression of TLR2, TLR4, and MD-2. RESULTS: The mRNA expression levels of TLR2, TLR4, and MD-2 in liver 2, 6, 12, and 24 h after in Subgroups AV were all significantly higher than those of Group N (P < 0.05 or P < 0.01) with the maximum level in the AV-12 h subgroup. The mRNA expression levels of TLR2, TLR4, and MD-2 in liver 6 h, 12 h, and 24 h after the VV injection of Subgroup AVA were all significantly lower than those of Group AV (P < 0.05 or P < 0.01). CONCLUSION: The mRNA expression levels of TLR2, TLR4, and MD-2 in liver tissue of alcohol-induced liver disease with VV sepsis, which may be reduced by treatment of cefoperazone sodium and LVFX, are associated with the development of VV sepsis. This treatment is effective on this disease. Dynamic monitoring of the mRNA expression levels of TLR2, TLR4, and MD-2 in liver tissue benefits observation of the VV sepsis progress and treatment.

[Changes of toll-like receptor, TNF-alpha and IL-10 in liver tissue of rats before and after intragastric infusion with alcohol with vibrio vulnificus sepsis].

OBJECTIVE: To detect the effects of antimicrobial agents on the toll-like receptor (TLR) and so on in liver tissue of rats after intragastric infusion with alcohol with vibrio vulnificus (VV) sepsis. METHODS: Sprague-Dawley rats were randomly divided into normal control group (N group, n = 6), rats after intragastric infusion with alcohol control group (group A, n = 6), drug intervention on rats after intragastric infusion with alcohol control group (group AA, n = 6), rats after intragastric infusion with alcohol with VV sepsis group (group AV, n = 24, killed at 2, 6, 12, 24 hours after injecting VV respectively, six rats per group), as well as drug intervention on rats after intragastric infusion with alcohol with vibrio vulnificus sepsis group (group AVA, n = 30, killed at 6, 12, 24 hours and one week after injecting VV respectively, six rats per group). The expressions and dynamic changes of TLR4 mRNA and so on by RT-PCR in liver tissue of each group were measured. RESULTS: The expressions of TLR4 mRNA in AV-6 hours group was 0.775 +/- 0.101, the expressions of TLR4 mRNA in AVA-6 hours group was 0.600 +/- 0.064; the expressions of TLR4 mRNA in AV-12 hours group was 0.918 +/- 0.133, the expressions of TLR4 mRNA in AVA-12 hours group was 0.583 +/- 0.112; the expressions of TLR4 mRNA in AV-24 hours group was 0.732 +/- 0.110, the expressions of TLR4 mRNA in AVA-24 hours group was 0.512 +/- 0.118. Compared with AV group, the expressions of TLR4 mRNA in liver diminished greatly in AVA group at 6, 12 and 24 hours after being injected with VV (AVA-6 hours group compare with AV-6 hours group, t = -3.573, P < 0.01; AVA-12 hours group compared with AV-12 hours group, t = - 4.722, P < 0.01; AVA-24 hours group compare with AV-24 hours group, t = - 3.340, P < 0.01). CONCLUSION: The treatment with antibacterial agents may reduced the expression of TLR and so on in liver of rats after intragastric infusion with alcohol with VV sepsis. The treatment with antibacterial agents may regulate the balance of the inflammatory response in VV sepsis and generate the visible therapeutical effect for VV sepsis.