OBJECTIVETo investigate the relationship among oxygen concentration, quorum sensing system, type secretion system, and biofilm production of Pseudomonas aeruginosa.

METHODSA total of 23 clinical strains of Pseudomonas aeruginosa were cultured at different levels of environmental oxygen for three days. Then biofilm mass and alginate were quantified. The expression levels of LasI and RhlI were detected by real time polymerase chain reaction (PCR). The secretion of exoenzyme S was examined by Western blot.

RESULTSBoth the biofilm mass (R=0.455, P=0.000) and alginate (R=0.367, P=0.000) were positively correlated with oxygen concentration. Real time PCR showed that the expression levels of LasI and RhlI were not significantly correlated with oxygen concentration (R=0.025, P=0.794; R=-0.044, P=0.653), the production of biofilm (R=0.001, P=0.990; R=0.011, P=0.909), or alginate(R=0.029, P=0.770; R=0.193, P=0.064). Western blot showed that the optimal oxygen concentration range for exoenzyme S secretion of Pseudomonas aeruginosa ranged 10% to 30%.

CONCLUSIONSHyperoxia can promote the production of biofilm and alginate by Pseudomonas aeruginosa. Las/Rhl system may not participate in biofilm production at the early stage due to the low bacteria amount. The increased production of biofilm may inhibit the expression of Type Secretion system and thus inhibit bacterial virulence.

Alginates ; metabolism ; Biofilms ; drug effects ; Oxygen ; metabolism ; Pseudomonas aeruginosa ; metabolism ; physiology ; Quorum Sensing ; drug effects ; physiology

BACKGROUNDImplanted medical catheter-related infections are increasing, hence a need for developing catheter polymers bonded to antimicrobials. We evaluated preventive effects of levofloxacin-impregnated catheters in catheter-related Psuedomonas aeruginosa (strain PAO1) infection.

METHODSDrug release from levofloxacin-impregnated catheters was measured in vitro. Levofloxacin-impregnated catheters and polyvinyl chloride (PVC) catheters were immersed in 5 ml 50% Luria Bertani medium containing 10(8) CFU/ml Pseudomonas aeruginosa then incubated for 6, 12, 24 or 48 hours at 37°C when bacteria adhering to the catheters and bacteria in the growth culture medium were determined. Impregnated and PVC catheters were singly implanted subcutaneously in mice, 50 µl (10(7)CFU) of PAO1 was injected into catheters. After the first and fifth days challenge, bacterial counts on implanted catheters and in surrounding tissues were determined microbiologically. Bacterial colonization and biofilm formation on implanted catheters were assessed by scanning electron microscopy.

RESULTSDrug release from levofloxacin-impregnated catheters was rapid. Levofloxacin-impregnated catheters had significantly fewer bacteria compared to PVC in vitro. After first and fifth day of challenge, no or significantly fewer bacteria adhered to impregnated catheters or in surrounding tissues compared to PVC. Scanning electron microscopical images after first day displayed from none to significantly fewer bacteria adhering to impregnated implanted catheters, compared to bacteria and microcolonies adhering to PVC catheters. After the fifth day, no bacteria were found on impregnated catheters, compared to clusters surrounding mucus-like substance and coral-shaped biofilms with polymorphonuclear leukocyte on PVC catheters. After the first day of challenge, secretion occurred in all implanted catheters with surrounding tissues mildly hyperaemic and swollen. After the fifth day, minute secretions inside impregnated catheters and no inflammation in tissues, whereas purulent secretion inside PVC catheters and abscesses in surrounding tissues.

CONCLUSIONLevofloxacin-impregnated catheter is a promising new strategy for prevention of catheter-related Psuedomonas aeruginosa infection.

Animals ; Biofilms ; drug effects ; Catheters, Indwelling ; microbiology ; Female ; Levofloxacin ; therapeutic use ; Mice ; Pseudomonas Infections ; prevention & control ; Pseudomonas aeruginosa ; pathogenicity

Antibacterial effect of tetracaine hydrochloride was studied. Tetracaine hydrochloride (preservative free) were incubated with Staphylococcus aureus, coagulase negative staphylococcus and Pseudomonas aeruginosa respectively, for 18 hours and for 2 minutes. Then it was diluted and cultured on nutrient agar plate. Colony counts were done after 18 hours. In case of 18 hours incubation, there was no growth of microbials in 0.5%, 0.1% tetracaine hydrochloride, but there was no inhibitory effect of 0.02% tetracaine hydrochloride on growth of microbials, irrespective of inoculum amount. In case of 2 minutes incubation with 0.5% tetracaine hydrochloride, there was no difference between the amount of microbial inoculum and colony count. Above indicates that tetracaine hydrochloride has no inhibitory effect on bacterial growth after short exposure of less than 2 minutes.
Anti-Bacterial Agents/*pharmacology ; Colony Count, Microbial ; Pseudomonas aeruginosa/*drug effects ; Staphylococcus aureus/*drug effects ; Tetracaine/*pharmacology ; Time Factors

OBJECTIVETo study MIC value of 7 boron derivatives namely [Boric acid (H(3)BO(3)), Anhydrous Borax (Na(2)B(4)O(7)), Sodium Borate (NaBO(2)), Diammonium Tetraborate (NH(4))(2)B(4)O(7), Sodium Perborate (NaBO(3)), Boron Trioxide (B(2)O(3)), Potassium Tetraborate (K(2)B(4)O(7))] on E. coli and P. aeruginosa and their effects on survival of bacteria in lake water and resistance against kanamycin antibiotic.

METHODSMIC values of Boron derivatives and antibiotic were studied by broth microdilution method. The effect of boron derivatives on survival of bacteria in lake water were also determined with plate count.

RESULTSSodium perborate was determined as the most effective substance among the studied substances. Effectiveness increased as temperature increased. E. coli was more affected from P. aeruginosa in 8 mg/mL sodium perborate concentration in lake water. Moreover, it was determined that MIC value of kanamycin antibiotic decreased 200 times by especially treating P. aeruginosa with sodium perborate in lake water. However, it can be stated that this change in resistance did not arise from microorganisms.

CONCLUSIONSodium perborate solution can be used supportedly in kanamycin antibiotic applications for P. aeruginosa. Future studies are necessary to explore the relation between sodium perborate and kanamycin which is effective on P. aeruginosa in lake water.

Borates ; pharmacology ; Escherichia coli ; drug effects ; Kanamycin Resistance ; Lakes ; microbiology ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects

OBJECTIVE: To observe the effect of biyuanshu oral liquid on the formation of pseudomonas aeruginosa biofilms in vitro. METHOD: Pseudomonas aeruginosa biofilm was established by plate culture and detected by Scanning electron microscopy and AgNO3 staining. After treated with different dosages of biyuanshu oral liquid and erythromycin, the pseudomonas aeruginosa biofilms were observed by AgNO3 staining and the number of viable bacteria were measured by serial dilution. RESULT: The pseudomonas aeruginosa biofilms could be detected by SEM at the seventh culture day and it was consistent with the detection of AgNO3 staining. The biyuanshu oral liquid and erythromycin have the effect on inhibiting the formation of pseudomonas aeruginosa biofilms. But with the already formed pseudomonas aeruginosa biofilms the inhibition was not significant. The serial dilution method showed that the viable counts of bacteria of biyuanshu oral liquid and erythromycin treated groups were significantly lower than those untreated groups (P < 0.05). CONCLUSION The biyuanshu oral liquid and erythromycin can inhibit the formation of pseudomonas aeruginosa biofilms in vitro.
Anti-Bacterial Agents ; pharmacology ; Biofilms ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Erythromycin ; pharmacology ; Pseudomonas aeruginosa ; drug effects ; growth & development

OBJECTIVETo investigate the inhibitory effects of Pseudomonas aeruginosa vaccine (PA-MSHA) on the proliferation of human nasopharyngeal cancer cells and explore the possible mechanism.

METHODSMTT assay was used to determine the cell growth of human nasopharyngeal cancer cell line 5-8F and 6-10B in vitro treated with the vaccine. The cell cycle distribution of the cells was detected by flow cytometry, and the expression levels of apoptosis and cycle-related proteins were evaluated by Western blotting.

RESULTSPA-MSHA treatment significantly suppressed the proliferation of 5-8F and 6-10B cells in a time- and concentration-dependent manner compared with the control group (P<0.05). The cells with PA-MSHA treatment exhibited a decreased percentage of cells entering S phase and a corresponding increase in G(1) phase cells in FACS analysis. The expression of cyclin D(1), CDK4, and CDK6 was significantly up-regulated, Bax protein up-regulated, and the anti-apoptosis protein Bcl-2 down-regulated in PA-MSHA-treated cells.

CONCLUSIONPA-MSHA can suppress the proliferation of nasopharyngeal carcinoma cell in vitro by affecting the cell cycle and promoting cell apoptosis.

Apoptosis ; drug effects ; Cancer Vaccines ; immunology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Nasopharyngeal Neoplasms ; pathology ; Pseudomonas aeruginosa ; immunology

OBJECTIVETo study the clinical characteristics of Pseudomonas aeruginosa (PA)-positive children in the pediatric intensive care unit, and to provide a basis for early diagnosis and reasonable treatment of PA infection.

METHODSThe clinical data of 62 children infected with PA in the pediatric intensive care unit were retrospectively reviewed,including age, affected organs, fever duration, hospital stay duration, mechanical ventilation duration, prognosis, underlying diseases, mortality, culture results and drug sensitivity test results.

RESULTSOf the 62 PA-positive children, 25 (40%) were aged under 6 months and 47 (76%) under 2 years, with a median age of 28.8 months. Twenty-seven showed one positive result for sputum culture or endotracheal tube aspirates culture, 3 showed one positive result for blood culture, and 32 showed more than two positive results for blood, sputum or endotracheal tube aspirates cultures. On average, 2.8 organs were affected in each patient, with the respiratory system involved most frequently (58 patients, 94%). The mean fever duration was 7.3 days and the mean hospital stay duration was 34.2 days. In the 62 patients, 35 (57%) were cured and 17 (27%) died. Mechanical ventilation was administered to 51 patients (82%) for a mean duration of 13.4 days. Fifty-one patients (82%) had underlying diseases. The 17 (27%) children who died had a mean age of 17.4 months and a mean CRP level of 52.6 mg/L; 14 of them had increased or normal white blood cell count, and 3 had a decreased white blood cell count.The antibiotic sensitivity of PA was 72.6% for cefoperazone/sulbactam, 70.8% for meropenem, 49.1% for imipenem, 65.1% for ceftazidime, and 44.3% for piperacillin/tazobactam. There was complete resistance to cephazolin, cefuroxime and cefotaxime.

CONCLUSIONSThe children under 2 years are prone to PA infection. Respiratory system involvements are common. Most of children infected with PA suffer from underlying diseases.The sensitivity of PA to common antibiotics is not high.

Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Humans ; Infant ; Intensive Care Units, Pediatric ; Male ; Microbial Sensitivity Tests ; Pseudomonas Infections ; blood ; drug therapy ; Pseudomonas aeruginosa ; drug effects ; Retrospective Studies

OBJECTIVETo analyze the isolation and the in vitro susceptibility of P. aeruginosa to antibiotics in our burn ward.

METHODSFive hundred and thirty six burn patients admitted to our ward from 1997 to 2003 were enrolled in the study, and the wound excretion, the tips of the venous catheter, the subeschar tissue samples, and the blood samples were collected for bacterial identification and antibiotic susceptibility test with VITEK-AMS system.

RESULTSThe isolation rate of P. aeruginosa from 1997 to 2003 was 24.51%, 23.94%, 21.01%, 40.06%, 36.17%, 46.76% and 55.72%, respectively. The antibiotic effect of the third generation of Cephalosporins against the said bacteria showed a tendency to decline. The susceptibility rate to Cefoperazone, Ceftazidime and Cefotaxime were respectively 71%, 66% and 79% in 1997; 47%, 25%, 39% in 1998; 22%, 16%, 25% in 2002; The third generation cephalosporins had almost lost their antibiotic activity against P. aeruginosa in 2003, with the susceptibility rate to Cefotaxime lowered to 2%. The susceptibility rate to Imipenem from 1997 to 2003 was 76%, 33%, 45%, 11%, 41%, 31%and 4%, respectively.

CONCLUSIONThe isolation rates of P. aeruginosa were steady during the period from 1997 to 1999, and they began to increase in 2000. The bacterial resistance to antibiotics increased gradually in recent years, and the strains of P. aeruginosa had become multi-drug resistant.

Anti-Bacterial Agents ; pharmacology ; Burn Units ; Burns ; microbiology ; Drug Resistance, Multiple, Bacterial ; Humans ; In Vitro Techniques ; Microbial Sensitivity Tests ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; drug effects ; isolation & purification

OBJECTIVETo investigate the resistant effect of houttuyfonate sodium (SH) combined with imipenem (IMP) against Pseudomonas aeruginosa (Pa) biofilms.

METHODThe two-fold dilution method was used to examine the minimum inhibitory concentration (MIC) of the tested drug. The crystal violet staining was applied to detect the effect of the combination of 1/2MIC, 1MIC, 2MIC of SH, single IMP, 1/2MIC of SH and IMP of various concentrations on the clearance rate of adherent bacteria, growth of biofilms and alginate production. Fluorescein diacetate (FDA)-propidium iodide (PI) doubling staining assay was employed to observe the bacterial viability and morphological changes after membrane dispersion of each drug group.

RESULTSodium houttuyfonate could enhance the effect of IMP against pseudomonas aeruginosa biofilms. Particularly, the combination group with the concentration of 2MIC showed the highest effect, with P < 0.001 compared with the negative control group. The above results were proved by the bacterial viability and biofilm morphology under fluorescence microscope.

CONCLUSIONAfter being combined with imipenem, sodium houttuyfonate shows a higher effect against biofilms. It is expected that the combination of the two drugs could improve the clinical efficacy of associated infections.

Alkanes ; pharmacology ; Biofilms ; drug effects ; growth & development ; Drug Synergism ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Microbial Viability ; drug effects ; Pseudomonas aeruginosa ; drug effects ; physiology ; Sulfites ; pharmacology

We designed and constructed an antibiotic screening system by using antibiotic responsive genes as reporters. Plasmid pCS26 carrying a promoterless luminescence reporter, luxCDABE, was used as the vector and the promoter regions of antibiotic responsive genes/operons from Escherichia coli were cloned upstream of the lux reporter to form the first part of the screening reporter array. Random promoter library of Salmonella enterica and Pseudomonas aeruginosa were screened for antibiotic responsive clones which consist of the second part of the screening array. The selected final reporter array responded to different antibiotics in distinct patterns and enabled in vivo high-throughput screening for antibiotics. Unknown antibiotics could, in general, be classified by analyzing the response patterns. This screening system is both sensitive and efficient and should prove to be a useful tool for screening new antibiotic compounds.
Anti-Bacterial Agents ; pharmacology ; Drug Evaluation, Preclinical ; methods ; Gene Expression Regulation, Bacterial ; drug effects ; Promoter Regions, Genetic ; genetics ; Pseudomonas aeruginosa ; drug effects ; genetics ; Salmonella enterica ; drug effects ; genetics