In vitro bacterial adherence to teicoplanin and calcium sulfate-soaked bone cement

The aim of this study was to assess in vitro the improvement in release kinetics for teicoplanin and the inhibition of bacterial adhesion on calcium sulfate-soaked PMMA discs. Calcium sulfate has been used in vivo and shown to be biocompatible, and prevention of bacterial adhesion may be expected with calcium sulfate-soaked polymethylmethacrylate (PMMA). Discs were made by adding teicoplanin and calcium sulfate in powder form to PMMA powder. The antibiotic concentration eluted from PMMA discs was assayed by agar diffusion assay. Nonadherent bacteria were removed by washing and adherent bacteria were detached by sonication. The suspension including nonadherent bacteria was seeded on sheep blood agar plate and incubated for 24 h at 37 degrees C for the growth of microorganisms. The teicoplanin released from discs containing calcium sulfate was higher than that released from discs which had not been soaked with calcium sulfate. The count of bacteria adhering to the calcium sulfate-soaked discs was lower than that from the discs without calcium sulfate. In conclusion, the addition of calcium sulfate to teicoplanin-loaded PMMA bone cement may provide local antibiotic concentrations higher than MIC values due to increased antibiotic release. Furthermore, calcium sulfate was found to be effective in reducing bacterial adherence to treated discs.     

Release of Antibiotics from Polymethylmethacrylate Cement

Abstract

The increase in resistance rates to antibiotics of bacteria isolated from infected hip joints, particularly staphylococci, prompted us to investigate the usefulness of antibiotic combinations such as gentamicin plus vancomycin. Cylinder test specimens of polymethylmethacrylate (PMMA) cement (Cemex^®, Tecres) containing gentamicin alone, vancomycin alone and both drugs in combination, were studied. The antibiotic concentrations were determined using a microbiological method and fluorescence polarization immunoassay (FPIA). The release of gentamicin alone, vancomycin alone and in combination from PMMA cement was prompt. The combination revealed synergistic antimicrobial activity against Escherichia coli and Enterococcus faecalis. FPIA showed that gentamicin and vancomycin delivery rates from PMMA cement were different. Gentamicin alone and in combination with vancomycin presented similar release rates from PMMA cement (1.50%). Vancomycin release from PMMA cylinders impregnated with the combination was lower (0.51%) than that from cylinders with vancomycin alone (1.16%). Vancomycin showed a 34.1% loss of microbiological activity at 37°C after 10 days of incubation; the reduction corresponded to 15.0% when measured by FPIA. Results obtained with test specimens are indicative for the preparation of antibiotic-impregnated cements for different human prostheses.     

In- Vitro Sensitivity of Amoxicillin/Clavulanic Acid (Augmentin®) to Isolated Beta-Lactamases and In- Vitro Antibacterial Activity

Summary

The in vitro sensitivity of amoxicillin alone and combined with clavulanic acid (ratio 4:1) as been studied by a spectrophotometric method utilizing crude extract of the following enzymes: TEMI, TEM2, SHV1, SHV2, TLE1, HMS1, LXA, P99, ENT208. The in-vitro antibacterial activity of ampicillin, amoxicillin alone and associated with clavulanic acid was also determined by an agar dilution method.

Clavulanate protects amoxicillin from the hydrolytic activity of plasmid mediated beta-lactamase, conferring a stability on the beta-lactam comparable with that of cefotaxime.

The protection of amoxicillin by means of clavulanic acid reduces the minimal concentration of antibiotic necessary to inhibit most bacterial species and allows bacteria to remain sensitive to the drug which might otherwise be resistant.     

Interference on Helicobacter pylori Growth and Adhesion by Omeprazole and Other Drugs

Abstract

Helicobacter pylori is the causative agent of gastritis and a co-agent in other gastroduodenal diseases. Gastroduodenal ulcer and MALT-lymphoma in particular, regress when patients are administered antimicrobial agents to eradicate infection. Sometimes eradication is not definitive and is difficult to check. The aim of our study was to test the antimicrobial activity of omeprazole on H. pylori in comparison with ampicillin and other anti-H₂ drugs (ranitidine and famotidine), and to evaluate their interference with bacterial adhesion of H. pylori. We also compared results of the agar dilution antibacterial sensitivity test on H. pylori to those obtained using a bacteria adherence to cell monolayers model, to see if drug activity was different against adhered bacteria. We evaluated omeprazole and ampicillin MIC90s (minimum inhibitory concentrations) against 20 H. pylori isolates by traditional agar dilution method and by exposing previously adhered bacteria to an Hep-2 monolayer to different drug concentrations. The activity against bacteria adhered to cell lines was evaluated by counting viable adhered bacteria after 1, 6, 12 hours of contact with drug. Interference with adherence to Hep-2 cells was also tested. Omeprazole and ampicillin MICs were comparable to other findings (omeprazole MIC90 was 12.5 μg/ml and ampicillin MIC90 was 0.016 μg/ml), while higher concentrations were necessary (4 × MIC90) against adhered bacteria. These findings suggest that MICs evaluated with traditional assays can have different predictivity than tests on adhered H. pylori.     

Efficacy of Teicoplanin,Administered in Two Different Regimens,in the Treatment of Experimental Endocarditis Due to Enterococcus faecalis

Abstract

Using a rabbit model of endocarditis, we studied the efficacy of teicoplanin against a strain of Enterococcus faecalis resistant to ampicillin. Rabbits were randomly assigned to receive no antibiotics, teicoplanin 12 or 18 mg/kg of body weight every 12h, for 9 days. The effect of treatment on bacterial counts of vegetations and survival of the animals was evaluated at the end of treatment and 10 days thereafter. The two treatment regimens of teicoplanin produced peak serum levels 18.51±1.84 and 34.66±4.19 μg/ml, and trough levels above 10×MIC of teicoplanin for the infecting organism. Both regimens resulted in significant bacterial reduction in the vegetations as compared to the control group (p<0.001). The drug prevented relapse of the infection 10 days after discontinuation of treatment. By increasing the teicoplanin dosage no additional therapeutic benefit was observed in terms of bacterial killing, sterilization of the vegetations, and survival of the animals, although the higher doses gave numerically superior results. These findings may have meaning for the optimum use of teicoplanin in the treatment of enterococcal endocarditis.     

Teicoplanin with Other Drugs: Possible Pharmacological Interactions

Summary

The contemporaneous employment of two or more drugs may present the risk of modifying the required therapeutic effect or producing adverse reactions. These interactions are of a pharmacokinetic and pharmacodynamic type. Teicoplanin is an antibiotic with a glycopeptide structure, produced by Actinoplanes teichomyceticus, active against both anaerobic and aerobic Gram-positive bacteria that are resistant to various chemotherapic drugs (β-lactam and macrolide antibiotics, tetracyclines, co-trimoxazole).

Then the aim of this work was to verify experimentally the possible pharmacological interactions between teicoplanin and oral hypoglycemic (phenformin and glibenclamide), or oral anticoagulant (warfarin) or bronchodilator (theophylline) drugs. Teicoplanin (3-15 mg/kg/die i.p. for 4 days) administration to the rat did not significantly (p > 0.05) modify the glycemia, prothrombin and partial thromboplastin times, the hypoglycemic effect of phenformin (2.5 mg/kg/die os for 4 days) and glibenclamide (0.5 mg/kg/die os for 4 days) or the anticoagulant effect of warfarin (0.5 mg/kg/die os for 4 days); moreover it did not significantly (p > 0.05) modify the pharmacokinetics of aminophylline (5 mg/kg i.v.) on the rabbit. In conclusion our results documented that teicoplanin does not interfere with phenformin, glibenclamide, or sodium warfarin activities nor with aminophylline pharmacokinetics.     

An Open Study of Teicoplanin in the Treatment of Gram-Positive Infections

Summary

Teicoplanin, a new glycopeptide antibiotic similar to vancomycin, was evaluated in treating 36 hospitalized patients suffering from various Gram-positive infections. The 36 patients received teicoplanin once daily as a mean intravenous injection of 550 mg/day (range 200-800 mg/day). Previous antimicrobial therapy was used in 28% of patients. The mean duration of therapy was 7.5 days (range 3-38 days). The overall clinical success rate was 94%. 24/36 patients (66%) had positive microbiology. Elimination of the pathogens was seen in 75% of all evaluable cases. Four patients with early prosthetic valve endocarditis due to coagulase negative Staphylococcus (3 patients) and Proptontbacterium acnes (1 patient) had a favorable clinical and microbiological outcome. No adverse drug reactions were observed. Teicoplanin is safe and effective in the therapy of many different infections caused by Gram-positive bacteria.     

Effect of Slime Production on the Antibiotic Susceptibility of Isolates from Prosthetic Infections

Summary

The antibacterial activity of 6 antibiotics towards 10 gram-positive and 6 gram-negative glycocalyx-producing strains, has been evaluated by employing a method which partially simulates the in vivo colonization of prosthetic devices.

The results showed that routine antibiotic sensitivity tests are not predictive about the response of the glycocalyx-embedded bacteria, and that prophylaxis may be useful with ofloxacin and clindamycin, before placing a prosthetic device. Once bacterial colonization had already occurred, however, none of the tested antibiotics was able to eradicate the sessile bacterial form. The minimum bactericidal concentration (MBC) values, indeed, were much higher than those determined on the planktonic form, and were much higher than serum and tissue levels that can be reached in vivo.     

Influence of In-Vivo Endotoxin Liberation on Anti-Anaerobic Antimicrobial Efficacy

Abstract

The ability of cefoxitin, clindamycin, imipenem, meropenem, metronidazole and piperacillin-tazobactam to cause Gram-negative anaerobic bacteria to release endotoxin and the influence of such liberated endotoxin on antibiotic efficacy were investigated in In-Vivo experiments in animal models. Experimental infections in various animal models (mice, hamster and infant rats) with cultures of wild and reference strains of Bacteroides fragilis group and Fusobacterium spp. were carried out by injecting these animals with different inocula (10⁶, 10⁷ and 10⁸ cfu/ml) of the bacterial suspension. Appropriate doses of the test antibiotics were then injected and the plasma lipopolysaccharide (endotoxin) release measured by the Limulus Amoebocyte Lysate (LAL) Assay. Evidence of worsening of the outcome of the infections post-therapy was assessed, including histopathological changes in the internal organs. Infection with generalized septicemia was established with F. nuclea-tum in the mice and hamster models while with the B. fragilis group, infections only led to intra-abdominal abscess formation. Plasma endotoxin release was higher in animals infected with F. nucleatum than B. fragilis and was unrelated to the bacterial inoculum. Imipenem, meropenem and cefoxitin, in that order, induced the highest levels of endotoxin activities in the animal model, particularly following F. nucleatum infection. Histological examination of the internal organs of various animals showed variation in the pattern of histopathological changes; grades 3-4 inflammatory changes in the liver were observed in the Fusobacterium-infected animals that were treated with the car-bapenems and cefoxitin. Therapy with the other antibiotics did not exacerbate anaerobic sepsis. In this study, bacteremia did not lead to massive endotoxin release and antibiotic therapy appeared not to have negatively influenced the outcome of most of the Gram-negative anaerobic infections, except for infections caused by Fusobacterium spp. However, it is conceivable that if the gastrointestinal tract is the source of the endotoxin in patients with systemic inflammatory response syndrome, then the obligate anaerobes like Bacteroides and Fusobacterium species, which are members of the gut flora, may play a major role in the unfavorable outcome of antibiotic therapy in some of these infections.     

Modulation of intracellular calcium in human neutrophils by peripheral benzodiazepine receptor ligands

Abstract

From January 1991 to June 1997 217 patients undergoing monolateral or bilateral total knee replacement (TKR) were consecutively enrolled in a prospective study on the incidence of postoperative infections and related risk factors. Regional antimicrobial prophylaxis (teicoplanin 400 mg) was used in 263 (95%) prostheses implanted; in the remaining 14 implants (5%) periopera-tive antibiotic prophylaxis (teicoplanin 800 mg) was administered as usual by systemic route. None of the patients experienced local or systemic adverse effects. Over the 2-year follow-up period, 8 (2.9%) primary site infectious complications were recorded, i.e. 4 superficial infections, which were cured without involvement of the prostheses, and 4 deep infections, which required prosthesis removal. Six infections occurred in patients who had undergone previous surgery of the same knee joint, and 2 in patients undergoing primary TKR (p=0.0005); diabetic patients had infections (13%) more frequently than non-diabetic patients (1.9%, p=0.01). Staphylococci were the leading organisms isolated from infections; however 3 strains of Escherichia coli were isolated from patients who had undergone a previous prosthesis implantation at the same knee joint. Regional administration of teicoplanin appears to be a safe and valuable prophylactic technique; however, in patients at risk of infection a prophylactic regimen which is also active against Gram-negative bacteria should probably be considered.     

In Vitro and In Vivo Antimicrobial Action of Fluphenazine

Abstract

The antipsychotic drug fluphenazine was obtained in a dry powder form and was screened with respect to 482 strains of bacteria, which included 170 Gram-positive and 326 Gram-negative strains. Nutrient agar plates containing increasing concentrations of fluphenazine (0-200 μg/ml) were used for the determination of the minimum inhibitory concentration (MIC) which was demonstrated by inoculating a loopful of an overnight peptone water culture of the organism on nutrient agar plates and determining the MIC against a control. Fluphenazine was detected to possess pronounced action against both Gram-positive and Gram-negative bacteria at 20-100 μg/ml. In the In Vivo studies it was seen that when fluphenazine was used at a concentration of 1.5 μg/g and 3 μg/g mouse body weight both the levels offered significant protection to Swiss strain of white mice when challenged with 50 minimum lethal dose (MLD) of a virulent strain of Salmonella typhimurium 74. The In Vivo data with fluphenazine were highly significant (p <0.001) according to the chi-square test.     

Combined Therapy of Teicoplanin and Caffeic Acid Phenethyl Ester (CAPE) in the Treatment of Experimental Mediastinitis in the Rat

Abstract

Post-sternotomy mediastinitis affects 1-3% of patients undergoing cardiac surgery and is lethal in 10-47% of these patients.

We investigated the effect of an antioxidant/anti-inflammatory agent, caffeic acid phenethyl ester (CAPE), in the attenuation of inflammatory response induced by methicillin-resistant Staphylococcus aureus (MRSA) infection in a rat experimental mediastinitis model. Rats, divided into six equal groups, received MRSA precolonized stainless steel wire pieces implanted into their mediastinal spaces. Control group and CAPE control group received saline and CAPE 10 μmol/kg.day^?1 respectively, where Group A received a single dose of teicoplanin 24 mg/kg i.m. for the first day and then 12 mg/kg.day^?1. Group B received teicoplanin as in Group A plus CAPE 10 μmol/kg. day^?1 intra-peritoneally. Group C received teicoplanin 60 mg/kg i.m. for the first day and then 30 mg/kg.day^?1 and Group D received teicoplanin as in Group C plus CAPE 10 μmol/kg.day^?1. By the end of 14 days rats were sacrificed and serum malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NO), urea and creatinine levels were evaluated. Mediastinal organ tissues were collected for histopathological analysis.

Infection rates in all the drug-treated groups were lower than the control groups (P = 0.002) but statistical significance was attained only between the groups A and D (P = 0.018). In connective tissues and the peribronchial area polymorphonuclear leukocytic (PNL) infiltration in the treatment groups, although becoming very close, did not reach statistical significance (P = 0.053, P = 0.075, respectively). PNL infiltration especially in the peribronchial tissues of the Group B animals was found to be significantly less than the Control and CAPE Control groups with P values of 0.013 and 0.010, respectively. MDA and MPO levels were significantly lower in the treatment groups (P < 0.001 and P < 0.001 respectively). Levels of the degradation products of NO were lower in treatment groups compared to two control groups (P = 0.003, P = 0.005). NO levels in Group D were lowest among all treatment groups (P = 0.001).

It has been demonstrated that although bacterial colonization can be controlled in mediastinitis, the inflammatory response persists. The combination of an antioxidant / anti-inflammatory agent, CAPE, added to standard antibiotic therapy might be effective in the treatment of post-sternotomy mediastinitis due to MRSA.     

Ciprofloxacin as Treatment for Conjunctivitis

Abstract

The authors studied the bactericidal action and therapeutic effectiveness of ciprofloxacin in treating external ocular infections (bacterial conjunctivitis and bac-terial blepharoconjunctivitis). 108 ambulatory patients with clinical signs of con-junctivitis and blepharoconjunctivitis were enrolled in the study. All subjects under-went a conjunctival swab before starting therapy and at 10 days, to identify the causative bacteria and their susceptibility to ciprofloxacin, following routine micro-biological methods. The reported therapeutic success rate (95%) and bacteriological analysis confirmed the effectiveness of ciprofloxacin in subjects with bacterial con-junctivitis and bacterial blepharoconjunctivitis. In vitro tests conducted 10 days after treatment confirmed the in vivo therapeutic effectiveness, even for those infections characterized by a difficult etiological identification which interferes with specific antibiotic therapy.     

Oral Ciprofloxacin for Treatment of Acute Bacterial Pharyngotonsillitis

Summary

The clinical efficacy and tolerability of ciprofloxacin orally administered at the dosage of 250 mg twice a day was evaluated in 25 patients affected by acute bacterial pharyngotonsillitis. All patients were non-responders to previous conventional antibiotic therapies due to in vitro resistance of the responsible bacteria, or possibly the low antibiotic concentration at the infection site. None of the patients had infections caused by group A β-haemolyticus streptococcus. Treatment with ciprofloxacin lasted for 5-10 days (mean 6.7). A favorable clinical response was observed in 92% of patients (15 resolutions and 7 improvements) at the end of the therapy and two weeks later (follow-up). One patient was not evaluable because of the unfortunate onset of glossitis that caused the interruption of the treatment. No other side-effects were recorded in the other 24 patients. The bacteriological response was excellent: 83% bacteriological eradication, 13% persistence and superinfection in only one patient (4%).

Ciprofloxacin administered orally at low dosages is highly effective in the treatment of bacterial pharyngotonsillitis and is also well tolerated.     

A Comparison of the E-Test and Proportion Methods for Susceptibility Testing of Mycobacterium tuberculosis

Abstract

The aim of this study was to investigate the correlation between three antibiotic susceptibility methods, the proportion method on Löwenstein Jensen medium (LJ medium), the proportion method on Middlebrook 7H11 agar (7H11 agar), and the E-test for Mycobacterium tuberculosis.

Fifty M. tuberculosis isolates were tested in vitro against isoniazid, rifampicin, streptomycin, and ethambutol according to the E-test, the proportion methods on 7H11 agar and LJ medium and then compared with a reference test which was the proportion method on 7H11 agar. The correlations between proportion method on 7H11 agar and proportion method on LJ medium for isoniazid, rifampicin, streptomycin, and ethambutol were 93.9%, 85.1%, 85.4% and 78.7% respectively. The correlations between the proportion method on 7H11 agar and the E-test were 83.1%, 78.8%, 84.7% and 80.5% respectively. There were no significant differences observed between the E-test and LJ medium compared to 7H11 agar. The average times to obtain susceptibility test results were 7 and 21 days for the E-test and agar proportion methods, respectively. The E-test may be suitable for replacing the proportion methods (7H11 agar and LJ medium) in routine practice due to its fast and easy application.     

Infection of the Pancreatic Duct Following Pancreas Transplantation with Bladder Drainage

Abstract

Combined kidney-pancreas transplantation represents a widely accepted therapy for endstage diabetic nephropathy. Drainage of the pancreatic juice into the urinary bladder is the preferred surgical technique in most centers. Between January 1987 and December 1994 a total of 85 pancreas transplantations with pancreatocys-tostomy were performed at the Innsbruck University Hospital. In all cases a polyvinylcatheter was placed into the pancreatic duct and drained transvesically to the exterior. During several weeks after transplantation pure pancreatic juice was harvested for immunological and microbiological monitoring. Whenever a patient required antibiotic treatment, antibiotic concentrations in pancreatic juice, urine or serum were determined by means of a biological test system using Bacillus subtilis. Nine different ATCC bacterial strains were incubated in pancreatic juice collected from transplant recipients and tested for their multiplication rate. Thirteen patients acquired an infection of the pancreatic duct. Non-fermentative bacteria, gram-negative rods, Enterococcus spp. and Candida spp. were the most often isolated organisms. The in vitro tests revealed that Pseudomonas aeruginosa, Adnetobacter calcoaceticus and Escherichia coli grew very well whereas Streptococcus agalactiae was unable to multiply in pancreatic juice. Ampicillin/sulbactam was found to be excreted in high concentrations into the pancreatic juice. Many other tested antibiotics (cephalosporins, carboxypeni-cillins and aminoglycosides) achieved levels below the minimum inhibitory concentrations (MICs) for most bacteria. Antibiotic treatment was required for up to 5 weeks to eliminate the pathogens from the pancreas but was successful in 11 out of the 13 patients at the end. The results of this study led to changes in our antibiotic policy and helped to improve the results after pancreatic transplantation.     

Renal Tolerability of Teicoplanin in a Case of Neonatal Overdose

Abstract

The literature does not contain reports regarding teicoplanin overdose in newborns. In a neonate with a history of recent postasphyctic acute renal failure which recovered within 7 days of life, antibiotic therapy with teicoplanin was started for sepsis due to Staphylococcus hominis. However, for 5 days the dosage was excessive (20 mg/kg twice daily instead of an initial dose of 16 mg/kg and then doses of 8 mg/kg once daily). Once this error had been noted, therapy was immediately suspended. Clinically the newborn had improved and blood culture at the end of the therapy was negative. Biohumoral tests revealed constantly normal levels of serum creatinine, serum cystatin C and blood nitrogen. Urinary parameters of tubulotoxicity were also within normal values. Urinary epidermal growth factor was increased. Teicoplanin was well tolerated at the renal level in the newborn even in this case of excessive dosage.     

Versatility of targeted antibiotic-loaded gold nanoconstructs for the treatment of biofilm-associated bacterial infections

Abstract

Background: We previously demonstrated that a photoactivatable therapeutic approach employing antibiotic-loaded, antibody-conjugated, polydopamine (PDA)-coated gold nanocages (AuNCs) could be used for the synergistic killing of bacterial cells within a biofilm. The approach was validated with a focus on Staphylococcus aureus using an antibody specific for staphylococcal protein A (Spa) and an antibiotic (daptomycin) active against Gram-positive cocci including methicillin-resistant S. aureus (MRSA). However, an important aspect of this approach is its potential therapeutic versatility.

Methods: In this report, we evaluated this versatility by examining the efficacy of AuNC formulations generated with alternative antibodies and antibiotics targeting S. aureus and alternative combinations targeting the Gram-negative pathogen Pseudomonas aeruginosa.

Results: The results confirmed that daptomycin-loaded AuNCs conjugated to antibodies targeting two different S. aureus lipoproteins (SACOL0486 and SACOL0688) also effectively kill MRSA in the context of a biofilm. However, our results also demonstrate that antibiotic choice is critical. Specifically, ceftaroline and vancomycin-loaded AuNCs conjugated to anti-Spa antibodies were found to exhibit reduced efficacy relative to daptomycin-loaded AuNCs conjugated to the same antibody. In contrast, gentamicin-loaded AuNCs conjugated to an antibody targeting a conserved outer membrane protein were highly effective against P. aeruginosa biofilms.

Conclusions: These results confirm the therapeutic versatility of our approach. However, to the extent that its synergistic efficacy is dependent on the ability to achieve both a lethal photothermal effect and the thermally controlled release of a sufficient amount of antibiotic, they also demonstrate the importance of carefully designing appropriate antibody and antibiotic combinations to achieve the desired therapeutic synergy.     

Comparison of teicoplanin and vancomycin in vitro activity on clinical isolates of Staphylococcus aureus

Abstract

Ninety-one clinical isolates of Staphylococcus aureus have been tested with the Kirby Bauer and the Etest® method to determine the susceptibility to glycopeptides in the 2007–2010 period. Five strains (5·5%) were resistant to vancomycin and nine (9·9%) to teicoplanin. Teicoplanin showed a median minimal inhibitory concentration (MIC) of 1 mg/l (range 0·125–24 mg/l), an MIC50 of 1 mg/l, and an MIC90 of 2 mg/l; vancomycin had a median MIC of 1·5 mg/l (range 0·38–4 mg/l), an MIC50 of 1·5 mg/l, and an MIC90 of 2 mg/l. More isolates were distributed on higher values of MIC for vancomycin. Inhibition halos induced by vancomycin-impregnated paper diskettes were slightly larger than those by teicoplanin. Glycopeptide resistance among methicillin-resistant Staphylococcus aureus in Italy is an underestimated phenomenon, possibly due to the described underestimation of glycopeptides MICs by the automatic broth microdilution method, when compared to agar MIC assays. A teicoplanin MIC creep, as reported for vancomycin, cannot be assumed.     

Temperature-sensitive liposomal ciprofloxacin for the treatment of biofilm on infected metal implants using alternating magnetic fields

Abstract

Implants are commonly used as a replacement for damaged tissue. Many implants, such as pacemakers, chronic electrode implants, bone screws, and prosthetic joints, are made of or contain metal. Infections are one of the difficult to treat complications associated with metal implants due to the formation of biofilm, a thick aggregate of extracellular polymeric substances (EPS) produced by the bacteria. In this study, we treated a metal prosthesis infection model using a combination of ciprofloxacin-loaded temperature-sensitive liposomes (TSL) and alternating magnetic fields (AMF). AMF heating is used to disrupt the biofilm and release the ciprofloxacin-loaded TSL. The three main objectives of this study were to (1) investigate low- and high-temperature-sensitive liposomes (LTSLs and HTSLs) containing the antimicrobial agent ciprofloxacin for temperature-mediated antibiotic release, (2) characterise in vitro ciprofloxacin release and stability and (3) study the efficacy of combining liposomal ciprofloxacin with AMF against Pseudomonas aeruginosa biofilms grown on metal washers. The release of ciprofloxacin from LTSL and HTSL was assessed in physiological buffers. Results demonstrated a lower transition temperature for both LTSL and HTSL formulations when incubated in serum as compared with PBS, with a more pronounced impact on the HTSLs. Upon combining AMF with temperature-sensitive liposomal ciprofloxacin, a 3 log reduction in CFU of Pseudomonas aeruginosa in biofilm was observed. Our initial studies suggest that AMF exposure on metal implants can trigger release of antibiotic from temperature sensitive liposomes for a potent bactericidal effect on biofilm.