Pre-treatment of central venous catheters with the cathelicidin BMAP-28 enhances the efficacy of antistaphylococcal agents in the treatment of experimental catheter-related infection

An in vitro antibiotic susceptibility assay for Staphylococcus aureus biofilms developed on 96-well polystyrene tissue culture plates was performed to elucidate the activity of the 27 residues cathelicidin peptide BMAP-28, quinupristin/dalfopristin (Q/D), linezolid, and vancomycin. Efficacy studies were performed in a rat model of staphylococcal CVC infection. Silastic catheters were implanted into the superior cava. Twenty-four hours after implantation the catheters were filled with BMAP-28. Thirty minutes later rats were challenged via the CVC with 1.0x10(6) CFU of S. aureus strain Smith diffuse. Administration of antibiotics into the CVC at a concentration equal to the MBC observed using adherent cells, or at a much higher concentration (1024 microg/mL) began 24 h later. The inhibition activities of all antibiotics against adherent bacteria were at least two-four-fold lower that against freely growing cells. When antibiotics were used in BMAP-28 pre-treated wells, they showed higher activities. The in vivo studies showed that when CVCs were pre-treated with BMAP-28 or with a high dose of antibiotics, biofilm bacterial load was reduced from 10(7) to 10(3) CFU/mL and bacteremia reduced from 10(3) to 10(1) CFU/mL. When CVCs were treated with both BMAP-28 and antibiotics, biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. These results suggest that CVC pre-treated with BMAP-28 represents an attractive choice for the treatment of device-related infections caused by staphylococci.     

Model of Staphylococcus aureus central venous catheter-associated infection in rats.

BACKGROUND AND PURPOSE: Staphylococcus aureus is an important cause of intravascular catheter-associated bacteremia. We developed a rat central venous catheter (CVC)-associated infection model to study pathogenesis and treatment. METHODS: A silastic lumen-within-lumen catheter and rodent-restraint jacket were designed. Subcutaneously tunneled catheters were inserted in the jugular vein of 20 male Sprague Dawley rats. Twelve rats (group 1) were inoculated with S. aureus via the CVC; three rats (group 2) were inoculated with S. aureus via the tail vein, five rats (group 3) served as uninfected controls; and three rats (group 4) were inoculated with S. aureus via the tail vein but did not undergo CVC insertion. Five to eight days after inoculation, animals were euthanized, CVCs were aseptically removed, and quantitative culture was done. Quantitative culture also was performed on blood, heart, liver, lungs, and kidneys. RESULTS: Infection, characterized by bacteremia and metastatic disease, was observed in all rats inoculated via the CVC with as few as 100 colony-forming units (CFU) of S. aureus. Rats of group 2 were not as likely to develop CVC-associated infection, and none of the animals of groups 3 or 4 developed infection. CONCLUSIONS: This model of CVC-associated infection should prove suitable for studying pathogenesis and treatment of the condition.     

RNAIII-inhibiting peptide improves efficacy of clinically used antibiotics in a murine model of staphylococcal sepsis

RNAIII-inhibiting peptide (RIP, YSPWTNF-NH2) is a quorum-sensing peptide inhibitor that prevents Staphylococcus aureus toxin production and biofilm formation. A mouse sepsis model was used to test the efficacy of RIP alone or in combination with conventional antibiotics in suppressing S. aureus-induced sepsis. Mice were injected intravenously with 3.0x10(6)CFU of S. aureus ATCC 25923 or with 3.0x10(6)CFU of S. aureus strain Smith diffuse. All animals were randomized to receive intravenously isotonic sodium chloride solution as a control, or 20 mg/kg RIP alone or combined with 20 mg/kg cefazolin, 10 mg/kg imipenem, or 10 mg/kg vancomycin immediately or 6 h after bacterial challenge. Main outcome measures were bacteremia and lethality. All compounds reduced lethality when compared to controls. Although, in general combined-treated groups had significant lower bacterial counts when associated to singly-treated groups only the combination between RIP and vancomycin with respect to cefazolin gave a statistically significant decrease in the lethality rate. Lowest lethality rates (10%) and bacteremia (<10(2)CFU/ml) were obtained when RIP was administered in combination with vancomycin. Because RIP can be synergistic with current antibiotic therapies and help to reduce S. aureus exotoxins production, it can be considered a promising agent to associate with antibiotics for further clinical research into treatment of sepsis.     

Eradication of biofilm cells of Staphylococcus aureus with tobramycin and cephalexin.

The kinetics of growth and formation of biofilm by Staphylococcus aureus were investigated under iron-limited conditions in the chemostat. The population of planktonic cells reached 5.5 x 10(9) cells/mL 24 h after inoculation (D = 0.05 h-1) and remained constant throughout. The number of biofilm cells of S. aureus colonizing the silicone tubing increased exponentially from 6 x 10(4) to 2.7 x 10(7) cells/cm2 (6 days later) and continued to increase at a reduced rate to 2.7 x 10(8) cells/cm2 on day 13. Planktonic cells of S. aureus were susceptible to tobramycin and cephalexin. The planktonic cells could be successfully eradicated with a combination of 5 micrograms tobramycin plus 100 micrograms cephalexin per millilitre. Exposure of young biofilm cells of S. aureus to 5 micrograms tobramycin plus 100 micrograms cephalexin per millilitre resulted in a rapid loss of cell viability. The percentage of survival dropped to less than 0.0001% after exposure to these concentrations of antibiotics for 3 h. Old biofilm cells of S. aureus were found to be extremely resistant to these antibiotics. The cell viability was reduced to 0.09% after exposure to 10 micrograms tobramycin plus 100 micrograms cephalexin per millilitre. The results suggest that it is possible to eradicate S. aureus infection at the early stage with tobramycin plus cephalexin. Any delay in implementing antibiotic therapy is likely to result in the failure of the treatment. It is important to note that the concentrations of antibiotics required for the eradication of young biofilm cells must be determined for the treatment of device-associated infections.     

Catheter lock technique: in vitro efficacy of ethanol for eradication of methicillin-resistant staphylococcal biofilm compared with other agents

Biofilm formation in central venous catheters (CVC) is a prerequisite for catheter-related bloodstream infection (CRBSI). The catheter lock technique has been used to treat biofilm infection, but the ideal agent, concentration and the minimum exposure time necessary to eradicate the biofilms are not clearly known. In this study, biofilm-producing strains of staphylococci were used to find out the minimum biofilm eradication concentration of ethanol compared with three other conventional antibacterial agents. Eight representative methicillin-resistant staphylococci, from colonized CVCs, were studied. The biofilms were exposed to 1, 5 and 10?mg?mL(-1) of gentamicin, ciprofloxacin and vancomycin. The ethanol concentrations used were 20%, 40% and 80%. Biofilms were examined for the presence of live organisms after exposure to these agents from 30?min to 24?h. The three antibiotics were unable to eradicate the biofilms even after 24?h, while ethanol at 40% concentration could do so for all the isolates in 1?h. Our study highlights the efficacy and rationale of using 40% ethanol for a short period as catheter lock solution to eradicate biofilms and thus to prevent CRBSI, instead of using high concentrations of antibiotics for extended periods.     

Mini-review: Antimicrobial central venous catheters – recent advances and strategies

Central venous catheters (CVCs) nowadays constitute critical devices used in medical care, namely in intensive care units. However, CVCs also represent one of the indwelling medical devices with enhanced risk of nosocomial device-related infection. Catheter-related infections (CRIs) are a major cause of patient morbidity and mortality, often justifying premature catheter removal and an increase in costs and use of resources. Adhesion and subsequent biofilm formation on the surfaces of indwelling catheters is elemental to the onset of pathogenesis. Seeking the prevention of CVC colonisation and CRI, a variety of approaches have been studied, tested and, in some cases, already applied in clinical practice. This review looks at the current preventive strategies often used to decrease the risk of CRIs due to colonization and biofilm formation on catheter surfaces, as well as at the more recent approaches under investigation.     

Mini-review: Antimicrobial central venous catheters--recent advances and strategies

Central venous catheters (CVCs) nowadays constitute critical devices used in medical care, namely in intensive care units. However, CVCs also represent one of the indwelling medical devices with enhanced risk of nosocomial device-related infection. Catheter-related infections (CRIs) are a major cause of patient morbidity and mortality, often justifying premature catheter removal and an increase in costs and use of resources. Adhesion and subsequent biofilm formation on the surfaces of indwelling catheters is elemental to the onset of pathogenesis. Seeking the prevention of CVC colonisation and CRI, a variety of approaches have been studied, tested and, in some cases, already applied in clinical practice. This review looks at the current preventive strategies often used to decrease the risk of CRIs due to colonization and biofilm formation on catheter surfaces, as well as at the more recent approaches under investigation.     

Increased tolerance of Staphylococcus aureus to vancomycin in viscous media

The increased viscosity observed in biofilms, adherent communities of bacterial cells embedded in a polymeric matrix, was hypothesized to induce increased tolerance of bacteria to antibiotics. To test this concept, planktonic Staphylococcus aureus cells were grown and exposed to vancomycin in media brought to specific viscosities in order to mimic the biofilm extracellular polymeric matrix. A viscous environment was observed to decrease the vancomycin susceptibility of planktonic S. aureus to levels seen for biofilms. Both planktonic S. aureus at a viscosity of 100 mPa s and staphylococcal biofilms were able to survive at >500 times the levels of the antibiotic effective against planktonic populations in standard medium. Time-dependent and dose-dependent viability curves revealed that more than one mechanism was involved in high S. aureus tolerance to vancomycin in viscous media. Increased viscosity affects antibiotic susceptibility by reducing diffusion and the mass transfer rate; this mechanism alone, however, cannot explain the increased tolerance demonstrated by S. aureus in viscous media, suggesting that viscosity may also alter the phenotype of the planktonic bacteria to one more resistant to antimicrobials, as seen in biofilms. However, these latter changes are not yet understood and will require further study.     

Staphylococcus aureus in Continuous Culture: A Tool for the Rational Design of Antibiotic Treatment Protocols

In vitro measures of the pharmacodynamics of antibiotics that account for the factors anticipated for bacteria in infected patients are central to the rational design of antibiotic treatment protocols. We consider whether or not continuous culture devices are a way to obtain these measures. Staphylococcus aureus PS80 in high-density continuous cultures were exposed to oxacillin, ciprofloxacin, vancomycin, gentamicin, daptomycin and linezolid. Contrary to results from low density retentostats as well as to predictions of traditional PK/MIC ratios, daily dosing with up to 100× MIC did not clear these cultures. The densities of S. aureus in these cultures oscillated with constant amplitude and never fell below 10(5) CFU per ml. Save for daptomycin "treated" populations, the densities of bacteria in these cultures remained significantly below that of similar antibiotic-free cultures. Although these antibiotics varied in their pharmacodynamic properties there were only modest differences in their mean densities. Mathematical models and experiments suggest that the dominant factor preventing clearance was wall-adhering subpopulations reseeding the planktonic population which can be estimated and corrected for. Continuous cultures provide a way to evaluate the potential efficacy of antibiotic treatment regimes in vitro under conditions that are more clinically realistic and comprehensive than traditional in vitro PK/PD indices.     

Planktonic aggregates of Staphylococcus aureus protect against common antibiotics

Bacterial cells are mostly studied during planktonic growth although in their natural habitats they are often found in communities such as biofilms with dramatically different physiological properties. We have examined another type of community namely cellular aggregates observed in strains of the human pathogen Staphylococcus aureus. By laser-diffraction particle-size analysis (LDA) we show, for strains forming visible aggregates, that the aggregation starts already in the early exponential growth phase and proceeds until post-exponential phase where more than 90% of the population is part of the aggregate community. Similar to some types of biofilm, the structural component of S. aureus aggregates is the polysaccharide intercellular adhesin (PIA). Importantly, PIA production correlates with the level of aggregation whether altered through mutations or exposure to sub-inhibitory concentrations of selected antibiotics. While some properties of aggregates resemble those of biofilms including increased mutation frequency and survival during antibiotic treatment, aggregated cells displayed higher metabolic activity than planktonic cells or cells in biofilm. Thus, our data indicate that the properties of cells in aggregates differ in some aspects from those in biofilms. It is generally accepted that the biofilm life style protects pathogens against antibiotics and the hostile environment of the host. We speculate that in aggregate communities S. aureus increases its tolerance to hazardous environments and that the combination of a biofilm-like environment with mobility has substantial practical and clinical importance.     

In vitro activity of amphibian peptides alone and in combination with antimicrobial agents against multidrug-resistant pathogens isolated from surgical wound infection

The in vitro activities of three amphibian peptides magainin II amide, citropin 1.1 and temporin A alone and in combination with eight clinically used antimicrobial agents (imipenem, ceftazidime, clarithromycin, vancomycin, amikacin, polymyxin E, ciprofloxacin and linezolid) were investigated against several multidrug-resistant Pseudomonas aeruginosa and Staphylococcus aureus strains isolated from surgical wound infections. Antimicrobial activities were measured by MIC, MBC and time-kill studies. P. aeruginosa strains were more susceptible to magainin II amide and less susceptible to temporin A. S. aureus isolates were highly susceptible to temporin A and citropin 1.1. The combination studies showed synergy between citropin 1.1 and clarithromycin. Magainin II amide and temporin A showed synergism with imipenem and ceftazidime. Finally, all peptides showed synergistic effects with polymyxin E. These results provide evidence for the potential use of these antimicrobial peptides in the topical or systemic treatment of surgical wound infections.     

Biofilm susceptibility to metal toxicity

This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.     

Application of a bacteriophage lysin to disrupt biofilms formed by the animal pathogen Streptococcus suis

Bacterial biofilms are crucial to the pathogenesis of many important infections and are difficult to eradicate. Streptococcus suis is an important pathogen of pigs, and here the biofilm-forming ability of 32 strains of this species was determined. Significant biofilms were completely formed by 10 of the strains after 60 h of incubation, with exopolysaccharide production in the biofilm significantly higher than that in the corresponding planktonic cultures. S. suis strain SS2-4 formed a dense biofilm, as revealed by scanning electron microscopy, and in this state exhibited increased resistance to a number of antibiotics (ampicillin, amoxicillin, ciprofloxacin, kanamycin, and rifampin) compared to that of planktonic cultures. A bacteriophage lysin, designated LySMP, was used to attack biofilms alone and in combination with antibiotics and bacteriophage. The results demonstrated that the biofilms formed by S. suis, especially strains SS2-4 and SS2-H, could be dispersed by LySMP and with >80% removal compared to a biofilm reduction by treatment with either antibiotics or bacteriophage alone of less than 20%; in addition to disruption of the biofilm structure, the S. suis cells themselves were inactivated by LySMP. The efficacy of LySMP was not dose dependent, and in combination with antibiotics, it acted synergistically to maximize dispersal of the S. suis biofilm and inactivate the released cells. These data suggest that bacteriophage lysin could form part of an effective strategy to treat S. suis infections and represents a new class of antibiofilm agents.     

The lipopeptides Pal-Lys-Lys-NH(2) and Pal-Lys-Lys soaking alone and in combination with intraperitoneal vancomycin prevent vascular graft biofilm in a subcutaneous rat pouch model of staphylococcal infection

Staphylococcal infections are often associated with the use of implantable medical devices. Such infections are difficult to treat because of biofilm resistance to antibiotics and are common causes of morbidity and mortality. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2x10(7) colony-forming units of bacterial strains. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis and five contaminated groups that received intraperitoneal vancomycin, Pal-Lys-Lys-NH(2) and Pal-Lys-Lys-soacked graft, and vancomycin plus Pal-Lys-Lys-NH(2) or Pal-Lys-Lys-soacked graft, respectively. The infection was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro antibiotic susceptibility assay for Staphylococcus aureus biofilms was performed to elucidate the same activity. When tested alone, vancomycin and lipopeptides showed comparable efficacies. All combinations showed efficacies significantly higher than that of each single compound. Vancomycin combined to Pal-Lys-Lys-NH(2) exerted the strongest anti-staphylococcal efficacies. The in vitro studies showed, that MIC and MBC values for vancomycin were lower in presence of lipopeptides. They reduce the bacterial load and to enhance the effect of vancomycin in the prevention of vascular graft staphylococcal infections.     

BioTimer Assay, a new method for counting Staphylococcus spp. in biofilm without sample manipulation applied to evaluate antibiotic susceptibility of biofilm

The medical device-related infections are frequently a consequence of Staphylococcus biofilm, a lifestyle enhancing bacterial resistance to antibiotics. Antibiotic susceptibility tests are usually performed on planktonic forms of clinical isolates. Some methods have been developed to perform antibiotic susceptibility tests on biofilm. However, none of them counts bacterial inoculum. As antibiotic susceptibility is related to bacterial inoculum, the test results could be mistaken. Here, a new method, BioTimer Assay (BTA), able to count bacteria in biofilm without any manipulation of samples, is presented. Moreover, the BTA method is applied to analyze antibiotic susceptibility of six Staphylococcus strains in biofilm and to determine the number of viable bacteria in the presence of sub-inhibitory doses of four different antibiotics. To validate BTA, the new method was compared to reference methods both for counting and antibiotic susceptibility tests. A high agreement between BTA and reference methods is found on planktonic forms. Therefore, BTA was employed to count bacteria in biofilm and to analyze biofilm antibiotic susceptibility. Results confirm the high resistance to antibiotics of Staphylococcus biofilm. Moreover, BTA counts the number of viable bacteria in the presence of sub-inhibitory doses of antibiotics. The results show that the number of viable bacteria depends on sub-inhibitory doses, age of biofilm and type of antibiotic. In particular, differently to gentamicin and ampicillin, sub-inhibitory doses of ofloxacin and azithromycin reduce the number of viable bacteria at lower extent in young than in old biofilm. In conclusion, BTA is a reliable, rapid, easy-to-perform, and versatile method, and it can be considered a useful tool to analyze antibiotic susceptibility of Staphylococcus spp. in biofilm.     

220D-F2 from Rubus ulmifolius Kills Streptococcus pneumoniae Planktonic Cells and Pneumococcal Biofilms

Streptococcus pneumoniae (pneumococcus) forms organized biofilms to persist in the human nasopharynx. This persistence allows the pneumococcus to produce severe diseases such as pneumonia, otitis media, bacteremia and meningitis that kill nearly a million children every year. While bacteremia and meningitis are mediated by planktonic pneumococci, biofilm structures are present during pneumonia and otitis media. The global emergence of S. pneumoniae strains resistant to most commonly prescribed antibiotics warrants further discovery of alternative therapeutics. The present study assessed the antimicrobial potential of a plant extract, 220D-F2, rich in ellagic acid, and ellagic acid derivatives, against S. pneumoniae planktonic cells and biofilm structures. Our studies first demonstrate that, when inoculated together with planktonic cultures, 220D-F2 inhibited the formation of pneumococcal biofilms in a dose-dependent manner. As measured by bacterial counts and a LIVE/DEAD bacterial viability assay, 100 and 200 µg/ml of 220D-F2 had significant bactericidal activity against pneumococcal planktonic cultures as early as 3 h post-inoculation. Quantitative MIC’s, whether quantified by qPCR or dilution and plating, showed that 80 µg/ml of 220D-F2 completely eradicated overnight cultures of planktonic pneumococci, including antibiotic resistant strains. When preformed pneumococcal biofilms were challenged with 220D-F2, it significantly reduced the population of biofilms 3 h post-inoculation. Minimum biofilm inhibitory concentration (MBIC)₅₀ was obtained incubating biofilms with 100 µg/ml of 220D-F2 for 3 h and 6 h of incubation. 220D-F2 also significantly reduced the population of pneumococcal biofilms formed on human pharyngeal cells. Our results demonstrate potential therapeutic applications of 220D-F2 to both kill planktonic pneumococcal cells and disrupt pneumococcal biofilms.     

Phage release from biofilm and planktonic Staphylococcus aureus cells

The ability of pathogenic staphylococci to form biofilms facilitates colonization and the development of chronic infections. Therapy is hampered by the high tolerance of biofilms towards antibiotic treatment and the immune system. We found evidence that lysogenic Staphylococcus aureus cells in a biofilm and in planktonic cultures spontaneously release phages into their surroundings. Phages were detected over a much longer period in biofilm cultures than in planktonic supernatants because the latter were degraded by secreted proteases. Phage release in planktonic and biofilm cultures was artificially increased by adding mitomycin C. Two morphologically distinct phages in the S. aureus strain used in this work were observed by electron microscopy. We postulate that phage-release is a frequent event in biofilms. The resulting lysis of cells in a biofilm might promote the persistence and survival of the remaining cells, as they gain a nutrient reservoir from their dead and lysed neighboring cells. This might therefore be an early differentiation and apoptotic mechanism.     

Detachment characteristics and oxacillin resistance of Staphyloccocus aureus biofilm emboli in an in vitro catheter infection model

Catheter-related bloodstream infections due to Staphylococcus aureus are of increasing clinical importance. The pathophysiological steps leading to colonization and infection, however, are still incompletely defined. We observed growth and detachment of S. aureus biofilms in an in vitro catheter-infection model by using time-lapse microscopy. Biofilm emboli were characterized by their size and their susceptibility for oxacillin. Biofilm dispersal was found to be a dynamic process in which clumps of a wide range of diameters detach. Large detached clumps were highly tolerant to oxacillin compared with exponential-phase planktonic cultures. Interestingly, the degree of antibiotic tolerance in stationary-phase planktonic cultures was equal to that in the large clumps. The mechanical disruption of large clumps reduced the minimal bactericidal concentration (MBC) by more than 1,000 times. The MBC for whole biofilm effluent, consisting of particles with an average number of 20 bacteria was 3.5 times higher than the MBC for planktonic cultures. We conclude that the antibiotic resistance of detached biofilm particles depends on the embolus size and could be attributed to nutrient-limited stationary-phase physiology of cells within the clumps. We hypothesize that the detachment of multicellular clumps may explain the high rate of symptomatic metastatic infections seen with S. aureus.     

Tetracycline and Chloramphenicol Efficiency Against Selected Biofilm Forming Bacteria

Despite the constantly increasing need for new antimicrobial agents, antibiotic drug discovery and development seem to have greatly decelerated in recent years. Presented with the significant problem of advancing antimicrobial resistance, the global scientific community has attempted to find alternative solutions; one of the most promising ones is the evaluation and use of old antibiotic compounds. A number of old antibiotic compounds, such as aminoglycosides, chloramphenicol, and tetracycline, are re-emerging as valuable alternatives for the treatment of difficult-to-treat infections. This study examined the in vitro potency for biofilm formation of five isolates (Klebsiella sp., Pseudomonas aeruginosa, Achromobacter sp., Klebsiella pneumoniae, and Bacillus pumilis) and the effects of antibiotics on these biofilms. Furthermore the quantitative analysis of planktonic, loosely attached cells, and their susceptibility to antibiotics was also determined. Twitching motility was observed to determine any effect in the biofilm forming capability of the isolates. All the isolates tested were efficient biofilm-forming strains in the polypropylene and borosilicate test tubes. Standard bacterial enumeration technique and CV staining produced equivalent results both in biofilm and planktonic assays. The biofilm formation of all the strains was affected in the presence of tetracycline or chloramphenicol. Highly significant decrease (P < 0.01) in biofilm formation was observed by treatment with chloramphenicol compared to tetracycline. In addition, the two antibiotics also affected adversely the planktonic and loosely attached cells of all isolates. Thus, testing the effects of older antibiotics on biofilms may supply useful information in addition to standard in vitro testing, particularly in diseases where biofilm formation is involved in the pathogenesis.     

左氧氟沙星浸涂导管对铜绿假单胞菌生物膜的影响

目的评估左氧氟沙星（levofloxacin,LFX）浸涂导管抑制铜绿假单胞菌粘附、定植,防止生物膜形成的能力。方法体外部分：制备LFX浸涂导管。LFX浸涂导管、PVC导管分别浸没在5 mL 50%LB培养液中（含PAO1 108CFU/mL）,37℃孵育6、12、24和48 h,在各时间点,予导管表面和导管培养液进行细菌计数。体内部分：小鼠皮下植入LFX浸涂导管或PVC导管,沿着导管注射PAO1菌液50μL（107CFU）。第1、5天,对植入导管及导管周围组织进行细菌计数及扫描电镜（SEM）观察。结果 （1）LFX浸涂导管显示药物的快速释放。（2）在各孵育时间点,LFX浸涂导管及导管培养液的细菌数较PVC导管均明显减少（P〈0.05）。（3）小鼠感染第1、5天,LFX浸涂植入导管表面没有或很少细菌;LFX浸涂导管较PVC导管能明显减少植入导管周围组织的细菌量（P〈0.05）。（4）SEM观察：感染第1、5天,LFX浸涂导管表面散在单个细菌或者没有细菌;而第1天,PVC导管表面大量细菌分散存在。第5天,导管表面＂珊瑚状＂生物膜形成。结论 LFX浸涂导管能抑制铜绿假单胞菌粘附、定植,防止生物膜形成,从而有效降低导管生物膜相关感染的发生。