Antimicrobial activity of ropivacaine and other local anaesthetics:

Approved drugs successfully repurposed against Leishmania based on machine learning predictions

Drug repurposing is a promising approach towards the discovery of novel treatments against Neglected Tropical Diseases, such as Leishmaniases, presenting the advantage of reducing both costs and duration of the drug discovery process. In previous work, our group developed a Machine Learning pipeline for the repurposing of FDA-approved drugs against Leishmania parasites. The present study is focused on an in vitro validation of this approach by assessing the antileishmanial effects of 10 predicted drug candidates. First, we evaluated the drugs' activity against promastigotes from two strains of L. infantum and one of L. major, which caused distinct clinical manifestations, using an MTT assay. The standard anti-Leishmania drug Amphotericin B was used as a positive control. Five molecules demonstrated anti-Leishmania effects, out of which Acebutolol, Prilocaine and Phenylephrine are described herein for the first time. When tested on promastigote growth, Acebutolol displayed IC50 values ranging from 69.28 to 145.53 µg/mL. Prilocaine exhibited IC50 values between 33.10 and 45.81 µg/mL. Phenylephrine, on the other hand, presented IC50 values >200 µg/mL. The two remaining drugs, Dibucaine and Domperidone, exhibited significantly low IC50 values varying between 0.58 and 1.05 µg/mL, and 6.30 and 8.17 µg/mL, respectively. Both compounds were previously described as anti-Leishmania agents in vivo. All five compounds demonstrated no notable cytotoxic effects on THP-1-derived macrophages at the IC50 concentrations, allowing for their testing on the intracellular form of L. major and L. infantum parasites. Interestingly, all compounds exhibited antileishmanial activity on amastigotes with enhanced IC50 values compared to the corresponding promastigotes. Noticeably, Dibucaine and Domperidone displayed IC50 values of at most 1.99 µg/mL. Acebutolol, Prilocaine and Phenylephrine showed IC50 values ranging from 13.84 to 66.81 µg/mL. Our previously published Computer-Aided repositioning pipelines of FDA-approved drugs as antileishmanial agents identified Dibucaine and Domperidone as candidates in support of previous in vivo studies. This study consolidates such findings through the in vitro validation against 2 Leishmania species, highly prevalent in Africa and Middle East, and reveals Acebutolol, Prilocaine, and Phenylephrine as novel anti-Leishmania effectors, confirming the relevance of our approach and calling for further investigations.

Does local infiltration analgesia in total joint arthroplasty offer any protection from prosthetic joint infections? An invitro experimental study

Many local anaesthetic agents are now reported to have anti-microbial properties in various studies, and this ability to inhibit microbial growth is not uniform. As local anaesthetics are commonly infiltrated into the surgical field for perioperative pain management, it is very important to know if this practice offers any protection against surgical site infections.

METHODS

In this study, three of the most common prosthetic joint infection-causing organisms, namely, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, were chosen and tested against the commonly used local anaesthetics. The suspension of each organism was inoculated onto three different Mueller-Hinton agar plates and a drop of an undiluted solution of each local anaesthetic agent is inoculated onto one of the three culture plates; vancomycin and gentamicin discs were used as controls.

RESULTS

The local anaesthetic agents tested could not inhibit the growth of any of the microorganisms. As there was no inhibition of bacterial growth in the experiment with the above three agents, further experiment with a diluted mixture was not performed.

CONCLUSIONS

It can be concluded that local infiltration of anaesthetic agents is less likely to provide any perioperative protection against prosthetic joint infections but may interfere with some diagnostic tests for microbiology.

The concentration of lidocaine and mepivacaine measured in synovial fluid of different joints of horses after single intra-articular injection

Objective

To determine the synovial fluid (SF) concentrations of lidocaine and mepivacaine after intra-articular injection with clinically relevant doses to the distal interphalangeal (DIP), metacarpophalangeal (MCP), middle carpal (MC), and tarsocrural (TC) joint at two different time points after injection in order to be able to compare concentrations with previously established concentrations associated with cytotoxicity and antimicrobial activity.

Procedures

In the first of two experiments, 20 joints (5 MC, 5 MCP, 10 DIP joints) of five horses under general anesthesia were injected with clinically referenced doses of 2% lidocaine. Simultaneously, the horses had 19 joints (5 MC, 5 MCP, 9 DIP joints) injected with clinically referenced doses of 2% mepivacaine. Synovial fluid samples were collected ~7 min after injection. In experiment 2, 23 joints of seven horses under standing sedation were injected with clinically referenced doses of 2% lidocaine. Similarly, the horses had 21 joints injected with 2% mepivacaine. Synovial fluid samples were collected ~23 min after injection. The concentration of mepivacaine and lidocaine in the obtained SF samples was assessed using high-performance-liquid-chromatography with mass spectrometry detection (HPLC MS).

Results

Synovial fluid was obtained 6.8 ± 1.5 (experiment 1) and 23 ± 4.3 (experiment 2) min following intra-articular injection of mepivacaine and lidocaine. Synovial fluid concentrations of experiment 1 for lidocaine and mepivaciane were 6.46–19.62 mg/mL (mean 11.96 ± SD 3.89 mg/mL) and 5.01–13.38 mg/mL (mean 8.18 ± SD 1.76 mg/mL), respectively. In experiment 2, concentrations were 2.94–10.40 mg/mL (mean 6.31± SD 2.23 mg/mL) for lidocaine and 2.10–8.70 mg/mL (mean 4.97 ± SD 1.77 mg/mL) for mepivacaine.

Conclusions and clinical relevance

Intra-articular LA injections in horses resulted in SF concentrations above those previously associated with cytotoxic effects in vitro but also above those associated with beneficial antimicrobial activities. Local anesthetic concentration was 33–60% lower after 23 min (experiment 2) than after 7 min (experiment 1).

Bacterial Nosocomial Infections: Multidrug Resistance as a Trigger for the Development of Novel Antimicrobials

Nosocomial bacterial infections are associated with high morbidity and mortality, posing a huge burden to healthcare systems worldwide. The ongoing COVID-19 pandemic, with the raised hospitalization of patients and the increased use of antimicrobial agents, boosted the emergence of difficult-to-treat multidrug-resistant (MDR) bacteria in hospital settings. Therefore, current available antibiotic treatments often have limited or no efficacy against nosocomial bacterial infections, and novel therapeutic approaches need to be considered. In this review, we analyze current antibacterial alternatives under investigation, focusing on metal-based complexes, antimicrobial peptides, and antisense antimicrobial therapeutics. The association of new compounds with older, commercially available antibiotics and the repurposing of existing drugs are also revised in this work.

Comparative Analysis of Different Local Anesthetic Solutions Available in Market: An In Vitro and Clinical Study

OBJECTIVES

 The study aimed to evaluate and compare various commercially available local anesthetic solutions.

MATERIALS AND METHODS

 A total of 150 commercially available local anesthetic cartridges of similar composition (2% lidocaine with epinephrine 1:100,000) were randomly collected and divided into 3 groups. The designations of groups were selected from their product names such that each group consisted of 60 cartridges. Group S (Septodont, France) Group M (Medicaine, Korea) and Group H (HD-Caine, Pakistan). The samples were divided into five sub-groups, each consisting of 10 cartridges from each group to investigate each parameter.

RESULTS

 The acquired data was statistically analyzed and compared (using SPSS version 12). Compositional analysis revealed a non-significant (P>0.05) difference when the three Groups were compared with standard lidocaine and epinephrine solutions. The mean pH values of samples from group S, M and H respectively fell within the range of pH values of commercially available solutions. Non-significant difference in EPT values of Group S and H was found when efficacy was compared (p = 0.3), however a significant difference (p < 0.01) was observed in contrast to Group M. Anti-bacterial activity was observed in all the group and a non-significant difference in cell viability values of Group S and M was found (p = 0.6), while the difference was significant in comparison to Group H.

CONCLUSION

 Within the limitations of these investigations, it appears that the properties of different manufacturers fall within the recommended ranges as mentioned in literature and do not appear to be statistically different in the variables we have tested.

[Antimicrobial effects of fentanyl and bupivacaine]

STUDY OBJECTIVE

In this study, we aimed to compare the antimicrobial effects of bupivacaine and fentanyl citrate and to reveal the impact on antimicrobial effect potential in the case of combined use.

DESIGN

In vitro prospective study.

SETTING

University Clinical Microbiology Laboratory.

MEASUREMENTS

In our study, in vitro antimicrobial effect of 0.05 mg.mL^-1 fentanyl citrate, 5 mg.mL^-1 bupivacaine were tested against Staphylococcus aureus American Type Culture Collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231 as Group F (Fentanyl Citrate) and Group B (Bupivacaine), respectively. S. aureus ATCC 29213, P. aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883 and Escherichia coli ATCC 25922 were cultured onto Mueller Hinton agar (Oxoid, UK) plates and Candida albicans ATCC 10231 were cultured onto Sabouraud dextrose agar (Oxoid, UK) plates for 18-24 hours at 37°C.

MAIN RESULTS

In terms of inhibition zone diameters, S. Aureus ATCC 29213, P. aeruginosa ATCC 27853, and C. albicans ATCC10231 values obtained after 12 and 24 hours of incubation were significantly higher in Group F than Group B (p < 0.001). In terms of inhibition zone diameters, E. coli ATCC 25922, and K. pneumomiae ATCC 13883 values obtained after 12 and 24hours of incubation were significantly higher in Group B than Group F (p < 0.001, E. coli 12ª hour p = 0.005).

CONCLUSIONS

Addition of fentanyl to Local Anesthetics (LAs) is often preferred in regional anesthesia applications in today's practice owing especially to its effect on decreasing the local anesthetic dose and increasing analgesia quality and patient satisfaction. However, when the fact that fentanyl antagonized the antimicrobial effects of LAs in the studies is taken into account, it might be though that it contributes to an increase in infection complications. When the fact that fentanyl citrate, which was used in our study and included hydrochloric acid and sodium hydroxide as protective agents, broadened the antimicrobial effect spectrum of LAs, had no antagonistic effect and showed a synergistic antimicrobial effect against E. Coli is considered, we are of the opinion that the addition of fentanyl to LAs would contribute significantly in preventing the increasing regional anesthesia infection complications.

[Antimicrobial effects of fentanyl and bupivacaine]

STUDY OBJECTIVE

In this study, we aimed to compare the antimicrobial effects of bupivacaine and fentanyl citrate and to reveal the impact on antimicrobial effect potential in the case of combined use.

DESIGN

In vitro prospective study.

SETTING

University Clinical Microbiology Laboratory.

MEASUREMENTS

In our study, in vitro antimicrobial effect of 0.05 mg.mL-1 fentanyl citrate, 5 mg.mL-1 bupivacaine were tested against Staphylococcus aureus American Type Culture Collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231 as Group F (Fentanyl Citrate) and Group B (Bupivacaine), respectively. S. aureus ATCC 29213, P. aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883 and Escherichia coli ATCC 25922 were cultured onto Mueller Hinton agar (Oxoid, UK) plates and Candida albicans ATCC 10231 were cultured onto Sabouraud dextrose agar (Oxoid, UK) plates for 18−24 hours at 37 °C.

MAIN RESULTS

In terms of inhibition zone diameters, S. Aureus ATCC 29213, P. aeruginosa ATCC 27853, and C. albicans ATCC10231 values obtained after 12 and 24 hours of incubation ​​were significantly higher in Group F than Group B (p <  0.001). In terms of inhibition zone diameters, E. coli ATCC 25922, and K. pneumomiae ATCC 13883 values obtained after 12 and 24 hours of incubation ​​were significantly higher in Group B than Group F (p <  0.001, E. coli 12ª hour p  = 0.005).

CONCLUSIONS

Addition of fentanyl to Local Anesthetics (LAs) is often preferred in regional anesthesia applications in today's practice owing especially to its effect on decreasing the local anesthetic dose and increasing analgesia quality and patient satisfaction. However, when the fact that fentanyl antagonized the antimicrobial effects of LAs in the studies is taken into account, it might be though that it contributes to an increase in infection complications. When the fact that fentanyl citrate which was used in our study and included hydrochloric acid and sodium hydroxide as protective agents, broadened the antimicrobial effect spectrum of LAs, had no antagonistic effect and showed a synergistic antimicrobial effect against E. Coli is considered, we are of the opinion that the addition of fentanyl to LAs would contribute significantly in preventing the increasing regional anesthesia infection complications.

Dibasic Derivatives of Phenylcarbamic Acid as Prospective Antibacterial Agents Interacting with Cytoplasmic Membrane

1-[2-[({[2-/3-(Alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium/azepan- ium oxalates or dichlorides (alkoxy = butoxy to heptyloxy) were recently described as very promising antimycobacterial agents. These compounds were tested in vitro against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 (reference and control strains), three methicillin-resistant isolates of S. aureus, and three isolates of vancomycin-resistant E. faecalis. 1-[3-(Dipropylammonio)-2-({[3-(pentyloxy-/hexyloxy-/heptyloxy)phenyl]carbamoyl}oxy)propyl]pyrrolidinium dichlorides showed high activity against staphylococci and enterococci comparable with or higher than that of used controls (clinically used antibiotics and antiseptics). The screening of the cytotoxicity of the compounds as well as the used controls was performed using human monocytic leukemia cells. IC50 values of the most effective compounds ranged from ca. 3.5 to 6.3 µM, thus, it can be stated that the antimicrobial effect is closely connected with their cytotoxicity. The antibacterial activity is based on the surface activity of the compounds that are influenced by the length of their alkoxy side chain, the size of the azacyclic system, and hydro-lipophilic properties, as proven by in vitro experiments and chemometric principal component analyses. Synergistic studies showed the increased activity of oxacillin, gentamicin, and vancomycin, which could be explained by the direct activity of the compounds against the bacterial cell wall. All these compounds demonstrate excellent antibiofilm activity, when they inhibit and disrupt the biofilm of S. aureus in concentrations close to minimum inhibitory concentrations against planktonic cells. Expected interactions of the compounds with the cytoplasmic membrane are proven by in vitro crystal violet uptake assays.

Synergistic antibacterial effects of analgesics and antibiotics against Staphylococcus aureus

The local use of analgesics and antibiotics is common during the treatment of periprosthetic joint infection (PJI). The effect of nonantimicrobial drugs on antibacterial activity is underappreciated in clinical practice. This study focuses on the novel assessment of the combined antibacterial effects of commonly used analgesics and antibiotics against methicillin-sensitive Staphylococcus aureus (MSSA)-pathogen associated with most PJIs. We identified that bupivacaine/lidocaine and ketorolac/gentamicin combinations yielded fractional inhibitory concentration indices below 0.4, indicative of synergistic antibacterial effect. Time-kill curves were used for in-depth characterization of the synergy, and the obtained results demonstrated pronounced synergistic effects of bupivacaine/lidocaine and ketorolac/gentamicin combinations against MSSA.

Synergistic anticandidal activity of etomidate and azoles against clinical fluconazole-resistant Candida isolates

Aim: The purpose of this study was to evaluate the effect of etomidate alone and in combination with azoles on resistant strains of Candida spp. in both planktonic cells and biofilms. Materials & methods: The antifungal activity of etomidate was assessed by the broth microdilution test; flow cytometric procedures to measure fungal viability, mitochondrial transmembrane potential, free radical generation and cell death; as well detection of DNA damage using the comet assay. The interaction between etomidate and antifungal drugs (itraconazole and fluconazole) was evaluated by the checkerboard assay. Results: Etomidate showed antifungal activity against resistant strains of Candida spp. in planktonic cells and biofilms. Etomidate also presented synergism with fluconazole and itraconazole in planktonic cells and biofilms. Conclusion: Etomidate showed antifungal activity against Candida spp., indicating that it is a possible therapeutic alternative.

Delivery of bupivacaine from UHMWPE and its implications for managing pain after joint arthroplasty

Total joint replacement is a widely used and successful surgical approach. Approximately 7 million US adults are currently living with a hip or knee replacement. However, the surgical procedures for total joint replacement are associated with significant postoperative pain, and current strategies do not adequately address this pain, which leads to patient dissatisfaction, reduced mobility, and increased risk of opioid addiction. We hypothesized that the ultra-high-molecular-weight polyethylene (UHMWPE) bearing surfaces used in total joint prosthetics could provide sustained release of the local anesthetic bupivacaine to provide relief from joint pain for an extended period of time after surgery. In this paper, we describe the production of bupivacaine-loaded UHMWPE (BPE) and measure the in vitro bupivacaine release kinetics of BPE. We found that bupivacaine could be released from BPE at clinically relevant rates for up to several days and that BPE possesses antibacterial effects. Therefore, bupivacaine-loaded UHMWPE is a promising material for joint replacement prostheses, and future studies will evaluate its safety and efficacy in in vivo models. STATEMENT OF SIGNIFICANCE: Total joint replacement is associated with significant pain and risk of infection. In our paper, we introduce bupivacaine-loaded ultra-high-molecular-weight polyethylene (BPE), which releases bupivacaine, a pain-treating drug, at doses comparable to currently used doses. Additionally, BPE inhibits the growth of infection-causing bacteria. Therefore, BPE may be able to reduce both postsurgical pain and risk of infection, potentially treating two of the most prominent complications associated with total joint replacement. To our knowledge, this is the first development of a material that can address both complications, and devices incorporating BPE would represent a significant advancement in joint arthroplasty prosthetics. More generally, the incorporation of therapeutic agents into ultra-high-molecular-weight polyethylene could impact many orthopedic procedures owing to its ubiquity.

Antimicrobial effects of local anaesthetics

After the introduction of cocaine to the medical practice, local anaesthetics (LA) became essential in pain control. LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. This study aimed to compare the antimicrobial effects of the topical antimicrobial agent mupirocine with those of the LA lidocaine and the combination of lidocaine and adrenalin. In our study, the in vitro antimicrobial effects of 1 mL sterile saline, 20 mg/mL mupirocine, 20 mg/mL Lidocaine, and 20 mg/mL Lidocaine and Adrenaline were tested against Staphylococcus aureus American type culture collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922 as Group C (Control), Group M (Mupirocine), Group L (Lidocaine), and Group LA (Lidocaine + adrenaline), respectively. S aureus ATCC 29213, P aeruginosa ATCC 27853, and E coli ATCC 25922 were cultured onto Mueller-Hinton agar (Oxoid, UK) plates for 18 to 24 hours at 37°C. Colonies from these plates were suspended in sterile saline and a 0.5 McFarland turbidity standard suspension (corresponding to 1.5 × 10⁸  CFU/mL) of each isolate was prepared. S Aureus ATCC 29213 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared with the group C (P ˂ 0.05). P aeruginosa ATCC 27853 inhibition zone diameter values of Group M and Group LA were significantly higher compared with the group C (P ˂ 0.05). E coli ATCC 25922 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared to the group C (P ˂ 0.05). LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. Considering that LAs show antimicrobial effects besides their analgesic effects, they may contribute to preventing the development and reducing the rate of surgical infections, decreasing the requirement to administer antibiotics. However, caution should be exercised not to antagonise the effective treatment of surgical infections, remembering that controversy on the antimicrobial effects of LAs remains in the literature. Therefore, further comprehensive studies with larger patient populations are warranted to demonstrate the antimicrobial effects of LAs.

A review and new insights to antimicrobial action of local anesthetics

Local anesthetics (LAs) are medications which can provide analgesia in distinct body regions through the blockade of voltage-gated sodium channels. Besides pain management, the supplemental role of LAs as antimicrobial agents has been documented in several studies. Different databases including PubMed, Scopus, and Web of Science with the name of different local anesthetics and related names for antimicrobial keywords were searched without time limitation. This review summarized different in vitro and in vivo studies regarding antimicrobial effects of different LAs with focuses on antimicrobial applications of most studied LAs, interaction with different agents which combined with LAs, and mechanisms of action and structural dependence of LAs antibacterial effects. Among different LAs, lidocaine is the most studied preparation. Reduction of the incidence of endophthalmitis after intravitreal injection, prophylaxis for surgical wound infections, prevention of the incidence of catheter-associated infections, oral biofilm reduction on the buccal mucosa, and prevention against bacteria that produced nosocomial infection are some examples of lidocaine antimicrobial application. Studies showed that different factors including structure, concentration, duration of exposure, type of microorganism tested, and temperature affect the degree of LA antimicrobial activity. In addition, various agents such as antibiotics, preservatives, opioids, epinephrine, and propofol can combine with LAs and affect their antimicrobial properties through synergistic or antagonistic action. Due to antibacterial activities, LAs could be applied in a clinic for prophylaxis of surgical site infection. In the application of LAs prior to diagnostic procedures caution should be needed; otherwise, when culturing the specimen, they could lead to false negative results.

The efficiency of topical anesthetics as antimicrobial agents: A review of use in dentistry

Topical anesthetics are commonly used in oral & maxillofacial surgery to control pain in the oral cavity mucosa before local anesthetic injection. These anesthetic agents come in many forms, developed for different usages, to minimize adverse reactions, and for optimal anesthetic efficiency. Earlier studies have revealed that these agents may also limit the growth of microorganisms in the area of anesthetic application. Many topical anesthetic agents show different levels of antimicrobial activity against various bacterial strains and Candida. The dosage of local anesthetic agent used in some clinical preparations is too low to show a significant effect on microbial activity. Efficiency of antimicrobial activity depends on the local anesthetic agent's properties of diffusion within the bloodstream and binding efficiency with cytoplasmic membrane, which is followed by disruption of the bacterial cell membrane. The antimicrobial properties of these agents may extend their usage in patients to both control pain and infection. To develop the topical local anesthetic optimal usage and antimicrobial effect, a collaborating antiseptic agent may be used to benefit the local anesthetic. However, more research is required regarding minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of topical local anesthetic agents with drug interaction between anesthetics and antiseptic agents.

The IMPROVE Guidelines (Ischaemia Models: Procedural Refinements Of in Vivo Experiments)

Most in vivo models of ischaemic stroke target the middle cerebral artery and a spectrum of stroke severities, from mild to substantial, can be achieved. This review describes opportunities to improve the in vivo modelling of ischaemic stroke and animal welfare. It provides a number of recommendations to minimise the level of severity in the most common rodent models of middle cerebral artery occlusion, while sustaining or improving the scientific outcomes. The recommendations cover basic requirements pre-surgery, selecting the most appropriate anaesthetic and analgesic regimen, as well as intraoperative and post-operative care. The aim is to provide support for researchers and animal care staff to refine their procedures and practices, and implement small incremental changes to improve the welfare of the animals used and to answer the scientific question under investigation. All recommendations are recapitulated in a summary poster (see supplementary information).

Local infiltration analgesia with ropivacaine in acute fracture of thoracolumbar junction surgery

STUDY DESIGN

Retrospective study.

INTRODUCTION

Local infiltration analgesia is effective in many surgeries as knee arthroplasty, but the analgesic efficacy of local infiltration analgesia with ropivacaine in trauma spine surgery in T10 to L2 has not been clarified. We conducted a trial to assess the analgesic efficacy of intraoperative local infiltration analgesia (LIA) with ropivacaine.

OBJECTIVE

The aim of the present study was to clarify the effect of intraoperative local infiltration analgesia with ropivacaine on postoperative pain for patients undergoing thoracolumbar junction fracture surgery.

METHODS

In a retrospective study, in 76 patients undergoing spine surgery for thoracolumbar junction fracture, 20ml of ropivacaine 7.5% (n R group=38) was infiltrated using a systematic technique, or no infiltration was realized (n M group=38). We assessed postoperative pain with Visual Analogue Scale (VAS) and morphine consumption in the 24 first hours.

RESULTS

VAS pain score upon awakening and at 2hours postoperatively were significantly lower in the ropivacaine group (P=0.01 and P=0.002). Rescue opioid requirement during the 24 first hours were about 50% lower in the ropivacaine group (P=0.01). No local or systemic side effects were observed.

CONCLUSION

Intraoperative LIA with ropivacaine in thoracolumbar junction fracture surgery may have an analgesic effect in postoperative pain control (24hours) with a reduction of VAS and morphine consumption.

Screening a repurposing library for potentiators of antibiotics against Staphylococcus aureus biofilms

Staphylococcus aureus biofilms are involved in a wide range of infections that are extremely difficult to treat with conventional antibiotic therapy. We aimed to identify potentiators of antibiotics against mature biofilms of S. aureus Mu50, a methicillin-resistant and vancomycin-intermediate-resistant strain. Over 700 off-patent drugs from a repurposing library were screened in combination with vancomycin in a microtitre plate (MTP)-based biofilm model system. This led to the identification of 25 hit compounds, including four phenothiazines among which thioridazine was the most potent. Their activity was evaluated in combination with other antibiotics both against planktonic and biofilm-grown S. aureus cells. The most promising combinations were subsequently tested in an in vitro chronic wound biofilm infection model. Although no synergistic activity was observed against planktonic cells, thioridazine potentiated the activity of tobramycin, linezolid and flucloxacillin against S. aureus biofilm cells. However, this effect was only observed in a general biofilm model and not in a chronic wound model of biofilm infection. Several drug compounds were identified that potentiated the activity of vancomycin against biofilms formed in a MTP-based biofilm model. A selected hit compound lost its potentiating activity in a model that mimics specific aspects of wound biofilms. This study provides a platform for discovering and evaluating potentiators against bacterial biofilms and highlights the necessity of using relevant in vitro biofilm model systems.

The stability and microbial contamination of bupivacaine, lidocaine and mepivacaine used for lameness diagnostics in horses

Local anaesthetics (LAs) are frequently used for diagnostic procedures in equine veterinary practice. The objective of this study was to investigate the physico-chemical stability and bacterial contamination of bupivacaine, lidocaine and mepivacaine used for lameness examinations in horses. The LAs were stored in 12 different groups at different temperatures (-18 °C to 70 °C), light intensities and in common veterinary field conditions for up to 16 months. The pH, presence of bacterial contamination and concentrations of LAs and methylparaben (a preservative present in lidocaine) were determined serially in both new and repeatedly punctured (RP) vials. Mepivacaine remained chemically stable. A 1.9% increase in bupivacaine concentration was evident in one group, whereas a 1.9-3.7% decrease was noted in six groups. Risk factors associated with a change in concentration were light and RP vials. Lidocaine concentration decreased 6.3% in one group and increased 5.3-7.2% in two groups. Risk factors for degradation were heat and RP vials whereas storage in practice vehicles was a risk factor for increased concentrations. Methylparaben decreased 8.3-75.0% in seven groups, and RP vials, heat and storage in practice vehicles were risk factors for degradation. No contamination was present in any of the LAs and pH remained stable. Commercially available solutions of lidocaine, mepivacaine and bupivacaine stored under common veterinary field conditions are extremely stable and sterile for extended periods. The minor changes in concentration documented in this study are unlikely to affect anaesthetic efficacy during equine lameness examinations. When using products containing methylparaben, degradation of the preservative over time is to be expected.

Antimicrobial effect of topical local anesthetic spray on oral microflora

BACKGROUND

To evaluate the antimicrobial activity of lidocaine (LD) topical anesthetic spray against oral microflora.

METHODS

Antimicrobial effects of 10% LD spray were assessed against six bacterial cultures obtained from volunteers: Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, Streptococcus salivarius, Streptococcus pyogenes, and Streptococcus sanguinis. The filter papers contained 50-µl LD, brain heart infusion (BHI) broth, or 0.2% chlorhexidine. Papers were placed on the cultured blood plates for 1-3 min. After the papers were removed, plates were incubated for 24 h. Bacterial growth on the contact areas was recorded as the antimicrobial score. The split mouth technique was use in for sample collection in clinical study. Filter papers soaked with either BHI broth or LD were placed on the right or left buccal mucosa for 1 min, and replaced with other papers to imprint biofilms onto the contact areas. Papers were placed on blood plates, incubated for 24 h, and antimicrobial scores were determined. Experiments were conducted for 2- and 3-min exposure times with a 1-day washout period.

RESULTS

LD exhibited bactericidal effects against E. coli, S. sanguinis, and S. salivarius within 1 min but displayed no effect against S. aureus, E. faecalis, and S. pyogenes. The antimicrobial effect of LD on oral microflora depended upon exposure time, similar to the results obtained from the clinical study (P < 0.05). LD showed 60-95% biofilm reduction on buccal mucosa.

CONCLUSIONS

Antimicrobial activity of 10% LD topical anesthetic spray was increased by exposure time. The 3 min application reduced oral microflora in the buccal mucosa.

Antibacterial properties of 2% lidocaine and reduced rate of endophthalmitis after intravitreal injection

PURPOSE

To determine whether the application of subconjunctival 2% lidocaine/0.1% methylparaben for anesthesia may reduce rates of endophthalmitis after intravitreal (IVT) injection.

METHODS

We performed in vitro experiments to determine the antibacterial properties of 2% lidocaine/0.1% methylparaben (lidocaine) against causative organisms of endophthalmitis. Isolates of Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus viridans from patients with endophthalmitis were incubated with or without lidocaine. Aliquots (100 µL) were plated on Mueller-Hinton (S. aureus and S. epidermidis) or blood agar plates (S. viridans) at 0, 10, 30, 120, and 240 minutes, and colonies were counted after 24 hours. A retrospective review of 15,042 IVT injections was performed from January 2004 to February 2011 to determine the rate of endophthalmitis with or without application of subconjunctival lidocaine for anesthesia.

RESULTS

Lidocaine demonstrated rapid bactericidal effects against all 3 organisms. After 10 minutes of exposure, there was approximately a 90% (P < 0.01), 95% (P < 0.001), and 92% (P < 0.001) reduction in colony forming units when compared with time 0 for S. aureus, S. epidermidis, and S. viridans, respectively. Complete elimination of colony forming units occurred at subsequent time points for each organism in contrast to logarithmic increase for control plates. There were a total of 0 cases of endophthalmitis of 6,853 IVT injections performed with subconjunctival lidocaine and 8 cases of endophthalmitis of 8,189 (0.1%) IVT injections performed with other methods of anesthesia (P = 0.03).

CONCLUSION

Application of subconjunctival 2% lidocaine/0.1% methylparaben for anesthesia may reduce the incidence of endophthalmitis after IVT injection.

Drug-loaded electrospun polylactide bundles

Bundle membranes were made by electrospinning poly(L-lactide) (PLLA) and PLLA/poly(ethylene glycol) (PEG) using the ionic properties of diclofenac sodium (DS), lidocaine hydrochloride (LHC), benzalkonium chloride (BC), and combinations thereof. The self-bundling of the fibers was initiated by using a designed grounded multi-needle electrode. Computer simulations on the electrostatic field distribution depended on the multi-needle position with respect to a grounded rotating drum collector which allowed the optimal arrangement of the electrospinning component set-up to obtain bundles. The combination of the ionization of the drugs as well as the utilization of the multi-needle electrode allowed the successful preparation of a series of mono-(DS, LHC, or BC), bi-(DS/LHC), and three-(DS/LHC/BC) drug(s)-loaded bundle membranes. Based on the Fourier transform infrared spectra, the drug systems were incorporated into the fibrous materials. The microbiological tests confirmed that the PLLA/ PEG bundle membranes containing BC (10 wt%), DS (30 wt%), DS/LHC (DS, 30 wt%; LHC, 30 wt%), and DS/LHC/BC (DS, 15 wt%; LHC, 15 wt%; and BC, 10 wt%) exhibited antibacterial activity against the pathogenic microorganism Staphylococcus aureus.

Effects of peritoneal lavage with lidocaine on survival of rats with fecal peritonitis

PURPOSE

To study the effects of peritoneal lavage with a 2% lidocaine solution, on the survival of the rats submitted to peritonitis caused by their own feces.

METHODS

Forty-eight Wistar rats, weighting between 300 g and 330 g (mean, 311,45 +/-9,67 g), were submitted to laparotomy 6 hours following induction of fecal peritonitis. Animals were randomly divided into four groups of 12 each as follows: 1- Control, no therapy; 2- Drying of the abdominal cavity; 3- Peritoneal lavage with saline and drying; 4- Peritoneal lavage with a 2% lidocaine solution and drying. Animals that died were submitted to necropsy and the time of their death recorded; survivors were killed on the post-operation 11th day and necropsied.

RESULTS

Death occurred within 52 h in all animals of group 1; within 126 h in 100% of those of group 2; within 50 h in 50% of those of group 3. All animals of group 4 survived. Survival on the 11 th day was higher in groups 3 and 4 than in groups 1 and 2 (p<0.001), and higher in group 4 than in group 3 (p<0.01).

CONCLUSION

Peritoneal lavage with a 2% lidocaine saline solution without adrenaline, prevented the mortality of all animals with fecal peritonitis.

In vitro antibacterial effects of topical local anesthetics

BACKGROUND

The antibacterial activities of local anesthetics are recognized.

OBJECTIVE

To investigate in vitro the activity of topical local anesthetic ointments at clinical doses.

METHODS

The activity of two different local anesthetic ointments including lidocaine 5% and lidocaine/prilocaine 2.5% was tested against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Streptococcus pyogenes and Enterococcus faecalis by the disc-diffusion method. Sterile discs containing topical local anesthetic drugs were prepared taking into account the doses of ointments used in clinical practice. The validity of the methodology was confirmed using topical antibacterial mupirocin. The inhibition zones of the discs were measured.

RESULTS

Mupirocin inhibited all the bacteria. Both local anesthetic ointments were found to be most effective on E. coli, whereas they had no effects on P. aeruginosa. Lidocaine 5% revealed antibacterial activity against S. aureus, S. epidermidis, E. coli, S. pyogenes and E. faecalis, but lidocaine/prilocaine 2.5% showed no activity on E. faecalis and inhibited S. pyogenes only at double doses. It was also observed that the antibacterial activity was in a dose-dependent manner.

CONCLUSION

In the light of these findings, it might be concluded that topical local anesthetic ointments in routine settings may have a preventive role against some bacteria.

The Antibacterial Activity of Tramadol Against Bacteria Associated with Infectious Complications After Local or Regional Anesthesia

BACKGROUND

Tramadol is a synthetic analog of codeine with opioid and local anesthetic properties. It is used as a central-acting analgesic, and recently, in subcutaneous or intradermal injections, as a local anesthetic. We investigated in vitro the antibacterial activity of tramadol in the absence of any local anesthetics against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa pathogens that can cause infectious complications after local or regional anesthesia.

METHODS

Bacterial cultures were grown for 18 h, diluted in sterile physiological saline, and incubated for 6 or 24 h at 37 degrees C with 6.25, 12.5, or 25 mg/mL tramadol. The mixtures were then plated onto blood agar and colony counts were recorded after 24 h incubation at 37 degrees C.

RESULTS

Tramadol had bactericidal activity against E. coli and S. epidermidis compared with controls: at 25 mg/mL for 6 h or at 12.5 mg/mL for 24 h, tramadol decreased by approximately 7 log(10) (P < 0.001) the colony counts of E. coli (100% kill). Similar results were obtained with S. epidermidis, with approximately 6 log(10) reduction (100% kill) when tramadol was used at 25 mg/mL for 24 h (P < 0.001). The antibacterial effect of 25 mg/mL tramadol was lower against S. aureus and P. aeruginosa, reducing the growth of these strains by approximately 3log(10) after 24 h (P < 0.001).

CONCLUSIONS

Tramadol has dose- and time-dependent bactericidal activity against E. coli and S. epidermidis, as well as antibacterial activity against S. aureus and P. aeruginosa. The antibacterial properties of tramadol may be useful for reducing the risk of bacterial infection after local or regional anesthesia.

Ipsilateral shoulder pain after thoracotomy surgery: a prospective, randomized, double-blind, placebo-controlled evaluation of the efficacy of infiltrating the phrenic nerve with 0.2%wt/vol ropivacaine

BACKGROUND

The aim of this prospective, randomized, double-blind, placebo-controlled study was to evaluate the efficacy of phrenic nerve infiltration with ropivacaine 0.2% on the incidence and severity of ipsilateral shoulder pain after thoracotomy in patients receiving continuous thoracic epidural analgesia.

METHODS

Fifty ASA physical status II-III patients, receiving thoracic epidural analgesia for post-thoracotomy pain, were randomly allocated to receive infiltration of the ipsilateral phrenic nerve with either ropivacaine 0.2% 10 mL (ropivacaine, n = 25), or saline 0.9% (control, n = 25) just before lung expansion and chest closure. A blinded observer recorded the incidence and severity of ipsilateral shoulder pain 6, 12, 24, 36 and 48 h after surgery. Postoperative respiratory function was also evaluated with blood gas analyses.

RESULTS

The cumulative incidences of ipsilateral shoulder pain during the first 24 h after surgery were 8/25 in the ropivacaine and 16/25 in the control groups (P = 0.047), with median (range) onset times for shoulder pain of 2 (2-24) h with ropivacaine and 0.5 (0.5-24) h in controls (P = 0.005). No differences were reported on the second postoperative day. The areas under the curves of the amount of pain over time were 0 (0-2760) mm h for the ropivacaine and 350 (0-1900) mm h for the control groups (P = 0.06). Postoperatively, similar reductions in indices of oxygenation were observed in both groups.

CONCLUSIONS

Phrenic nerve infiltration with ropivacaine 0.2% 10 mL reduced the incidence and delayed the onset of ipsilateral shoulder pain during the first 24 h after open lung resection, with no clinically relevant effects on respiratory function.

Evaluation of a local anesthetic delivery system for the postoperative analgesic management of canine total ear canal ablation--a randomized, controlled, double-blinded study

OBJECTIVE

To determine if a constant rate local anesthetic delivery system is more effective than continuous intravenous (IV) morphine infusion for postoperative analgesia.

ANIMALS

Twenty client-owned dogs undergoing total ear canal ablation.

METHODS

Dogs were randomly assigned to the lidocaine group (LID) or the morphine group (MOR). The LID group received a constant rate infusion of lidocaine locally and a continuous IV infusion of saline, while the MOR group received a constant rate infusion of saline locally and a continuous IV infusion of morphine. The primary investigator evaluated each patient and determined a hospital behavior score, anesthesia recovery score, preoperative pain score, and serial postoperative pain and sedation scores over 38 hours. Pain and sedation observations were videotaped and scored by three additional evaluators. Evaluators were blinded to treatment assignments.

RESULTS

There were no significant differences in age, weight, hospital behavior scores or anesthesia recovery scores. The primary investigator's pain scores were not significantly different, but sedation scores were significantly lower for the LID group. Sedation and pain scores by the video evaluators were not significantly different between groups. Kappa agreement between observers was poor, but better agreement was noted between sedation scores than pain scores. Drug-related complications were significantly lower in the LID group (n = 0) compared with the MOR group (n = 5). Wound complications were not significantly different (LID = 4, MOR = 4). Intravenous delivery complications occurred in 12 (60%) patients. Local delivery complications occurred in five (25%) dogs. Delivery complications were not significantly different between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Continuous incisional lidocaine delivery was an equipotent and viable method of providing postoperative analgesia compared with IV morphine. Lidocaine delivery resulted in a trend toward lower pain scores, significantly lower sedation scores, and no dogs requiring analgesic rescue. Wound complications secondary to local infusion were minor and self-limiting. Drug-related complications occurred only in the MOR group.

Detection of Neisseria meningitidis DNA from skin lesion biopsy using real-time PCR: usefulness in the aetiological diagnosis of purpura fulminans

OBJECTIVE

The present study evaluated the usefulness of a real-time polymerase chain reaction (rtPCR) assay for the detection of Neisseria meningitidis (Nm) and genogrouping on skin lesion biopsies in patients with purpura fulminans (PF).

DESIGN

Retrospective single-centre study.

SETTING

Adult and paediatric intensive care units at the University Hospital of Rouen.

PATIENTS

All patients admitted between January 2000 and January 2006, with a final diagnosis of PF and for which a skin biopsy and blood cultures were performed, were included.

INTERVENTIONS

Skin biopsy and blood cultures were used for culture and rtPCR.

MEASUREMENTS AND MAIN RESULTS

Thirty-four patients fulfilled the criteria (27 children and 7 adults). Nm rtPCR performed on skin biopsy was positive in 100% (34/34) of cases, compared with only 14.7% (5/34) for skin culture (p=0.0001). rtPCR genogrouping on skin biopsy was positive in 58.8% (20/34) of the cases compared with 14.7% (5/34) for skin culture (p=0.0013). For patients (n=17) in whom rtPCR was performed both on blood and skin biopsy, skin biopsy gave a significantly higher rate of Nm detection [100% (17/17) vs. 58.8% (10/17); p=0.023] and genogroup characterisation [76.5% (13/17) vs. 35.3% (6/17); p=0.045] than blood. We encountered no specimen with culture-positive and rtPCR-negative results (negative predictive value of rtPCR 100%).

CONCLUSION

In suspected PF cases, skin biopsy is more reliable to identify Nm and its genogroup than blood or, probably, CSF, especially when PCR methods are used. This could help the implementation of public health interventions, especially concerning a vaccination policy.

Antibacterial Activity of Clonidine and Neostigmine In Vitro

We conducted an in vitro study to investigate the antibacterial activity of clonidine and neostigmine on common microorganisms encountered during infectious complications after regional anesthesia. Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated during 1, 3, 6, and 24 h at 37 degrees C with concentrations of 37.5, 75, and 150 microg/mL of clonidine and 125, 250, and 500 microg/mL of neostigmine. After 24 h incubation at 37 degrees C, the colony counts were compared by two-way analysis of variance. The mean colony counts for S. aureus decreased significantly from control as the exposure to clonidine increased (P < 0.05), with a approximately 100% kill at 6 h for the largest concentration (150 microg/mL) and at 24 h for the intermediate concentration (75 microg/mL). Similar results were observed for S. epidermidis, with a approximately 100% kill at 6 h for the largest concentrations (75 and 150 microg/mL). No bactericidal activity of clonidine was observed for E. coli and no bactericidal activity of neostigmine was observed for any of the tested strains. In the conditions of this experiment, clonidine, but not neostigmine, exhibited a concentration-dependent and time-dependent bactericidal activity in vitro on the microorganisms most frequently encountered in infectious complications after regional anesthesia.

Risk factors for bacterial catheter colonization in regional anaesthesia

Background

Although several potential risk factors have been discussed, risk factors associated with bacterial colonization or even infection of catheters used for regional anaesthesia are not very well investigated.

Methods

In this prospective observational trial, 198 catheters at several anatomical sites where placed using a standardized technique. The site of insertion was then monitored daily for signs of infection (secretion at the insertion site, redness, swelling, or local pain). The catheters were removed when clinically indicated (no or moderate postoperative pain) or when signs of potential infection occurred. After sterile removal they were prospectively analyzed for colonization, defined as > 15 colony forming units.

Results

33 (16.7%) of all catheters were colonized, and 18 (9.1%) of these with additional signs of local inflammation. Two of these patients required antibiotic treatment due to superficial infections. Stepwise logistic regression analysis was used to identify factors associated with catheter colonization. Out of 26 potential factors, three came out as statistically significant. Catheter placement in the groin (odds-ratio and 95%-confidence interval: 3.4; 1.5–7.8), and repeated changing of the catheter dressing (odds-ratio: 2.1; 1.4–3.3 per removal) increased the risk for colonization, whereas systemic antibiotics administered postoperatively decreased it (odds ratio: 0.41; 0.12–1.0).

Conclusion

Colonization of peripheral and epidural nerve catheter can only in part be predicted at the time of catheter insertion since two out of three relevant variables that significantly influence the risk can only be recorded postoperatively. Catheter localisation in the groin, removal of the dressing and omission of postoperative antibiotics were associated with, but were not necessarily causal for bacterial colonization. These factors might help to identify patients who are at increased risk for catheter colonization.

Local Anesthetic Infusion Pumps Improve Postoperative Pain after Inguinal Hernia Repair: A Randomized Trial

Pain after an open inguinal hernia repair may be significant. In fact, some surgeons feel that the pain after open repair justifies a laparoscopic approach. The purpose of this study was to determine if the use of local anesthetic infusion pumps would reduce postoperative pain after open inguinal hernia repair. We performed a prospective, double-blind randomized study of 45 open plug and patch inguinal hernia repairs. Patients were randomized to receive either 0.25 per cent bupivicaine or saline solution via an elastomeric infusion pump (ON-Q) for 48 hours, at 2 cc/h. The catheters were placed in the subcutaneous tissue and removed on postoperative day 3. Both groups were prescribed hydrocodone to use in the postoperative period at the prescribed dosage as needed for pain. Interviews were conducted on postoperative days 3 and 7, and patient's questionnaires, including pain scores, amount of pain medicine used, and any complications, were collected accordingly. During the first 5 postoperative days, postoperative pain was assessed using a visual analog scale. Twenty-three repairs were randomized to the bupivicaine group and 22 repairs randomized to the placebo group. In the bupivicaine group, there was a significant decrease in postoperative pain on postoperative days 2 through 5 with P values <0.05. This significant difference continued through postoperative day 5, 2 days after the infusion pumps were removed. Patients who had bupivicaine instilled in their infusion pump had statistically significant lower subjective pain scores on postoperative days 2 through 5. This significant difference continued even after the infusion pumps were removed. Local anesthetic infusion pumps significantly decreased the amount of early postoperative pain. Pain relief persisted for 2 days after catheter and pump removal.

Evolving spinal analgesia practice in palliative care

Intraspinal analgesia can be helpful in some patients with intractable pain. Over 15 years palliative care professionals evolved their spinals policy through a repeated series of evaluations, discussions and literature reviews. One hundred intraspinal lines were then reviewed. Notable changes in policy were the switch from epidurals to intrathecals, and the insertion of lines during working hours rather than as emergencies. Our efficacy, and frequency of adverse effects, is equal or better to published studies. Key issues in reducing adverse effects were the improved care of the spinal line exit site, a change from bolus administration to continuous infusions, and modifying line insertion techniques. Current policy is to use continuous infusions of diamorphine and bupivacaine in a 1:5 ratio through externalized intrathecal lines. The lines are effective in approximately two thirds of patients and can be kept in place for up to 18 months. The policy continues to be updated and common documentation is now in place.

Lumbar spondylodiscitis caused by Propionibacterium acnes after epidural obstetric analgesia

IMPLICATIONS

We report a case of Propionibacterium acnes spondylodiscitis after the placement of an epidural catheter for obstetric analgesia. This observation should alert the anesthesiologist to the fact that infection, although rare, may occur after uneventful epidural analgesia in the healthy parturient and reinforces the importance of aseptic technique during epidural catheter insertion.