Bacterial growth in ropivacaine hydrochloride

Pharmacological Insights of Ropivacaine and Clinical Applications: A Narrative Review

This review focuses on ropivacaine, a long-acting amide local anaesthetic, detailing its pharmacology and clinical applications. The article highlights its applications in providing analgesia, prolonging pain relief, and improving recovery outcomes in surgical settings. Ropivacaine is particularly effective for epidural labor analgesia in obstetrics, promoting stable hemodynamics and rapid onset when used with adjuvants. Its prolonged anesthetic effects reduce the need for postoperative opioids in peripheral nerve blocks. Intrathecal administration may enhance functional recovery and postoperative analgesia in various surgical procedures. While effective in treating acute pain, its role in chronic pain management remains unclear, indicating a need for further research. The review underscores the versatility and efficacy of ropivacaine in acute pain management and the importance of exploring its potential in chronic pain treatment.

Local anesthetics as a tool for Staphylococcus spp. control: a systematic review

The objective of this work was to carry out a systematic review on the effectiveness of local anesthetics as antimicrobial agents against Staphylococcus spp. Searches were performed in the PubMed, Web of science, Scopus, Embase and Lilacs databases. As inclusion criteria, complete original articles, with in vitro experimental tests with the application of selected anesthetics and bacteria of the genus Staphylococcus spp. This review followed the methodological checklist for writing papers reporting systematic reviews by the PRISMA statement. The risk of bias was assessed according to the JBI critical appraisal checklist. Analysis was performed using an anesthetic-moderated simple linear regression model. This systematic review was registered by the Open Science Framework-OSF ( https://doi.org/10.17605/OSF.IO/C5JM7 ). Initially, 1141 articles were found, of which, after careful selection, 52 articles were analyzed. Lidocaine was the most commonly used anesthetic, being evaluated in 35 of the articles. S. aureus ATCC 25923 was the standard microorganism in 17 articles. The impact of the anesthetic concentration in relation to the antimicrobial effect was evaluated and the results showed that there was no statistically significant difference. (F [5, 12] = 0.688 p = 0.642), even when taking into account the moderator effect of anesthetics individually. Therefore, although the antimicrobial effect of local anesthetics was demonstrated in 82.7% of the studies evaluated, great heterogeneity of the results was found, which made it impossible to carry out a meta-analysis and make recommendations based on the evidence.

LC-MS/MS assisted biomonitoring of ropivacaine and 3-OH-ropivacaine after plane block anesthesia for cardiac device implantation

Introduction: Ropivacaine is a popular local anesthetic used for regional anesthesia or for pain management. Although designed as an enantiomerically pure drug, an aspect that reduces the adverse effects, its toxicological effects are still a risk. As such, biomonitoring to assure appropriate dosage and bioavailability are essential to avoid complications during or post-surgery. Methods: The study focused on developing a sensitive, selective, and accurate liquid chromatography-mass spectrometry (LCMS/MS) method which facilitates the biomonitoring of ropivacaine and its main metabolite in plasma after regional anesthesia using ropivacaine. Results and Discussion: The method was validated with regards to all relevant parameters, such as sensitivity, selectivity, accuracy, precision, and the effect of sample matrix. The method was successfully used in a pilot study, which included one patient undergoing plane block anesthesia for cardiac device implantation. The results showed the method is appropriate for its intended purpose and could even be used in other, similar applications.

Ropivacaine: A Novel Local Anaesthetic Drug to Use in Otorhinolaryngology Practice

Ropivacaine is a long-acting amide local anaesthetic agent which has a significant vasoconstrictive property, long duration of action, least central nervous system and cardiac complications due to the pure (S)-enantiomer property by reversible inhibition of sodium ion influx in nerve fibres. By using additives the duration of analgesia may be prolonged. Ropivacaine has been used routinely in our otorhinolaryngology procedures since 2010 (10 years). The present article details the clinical applications of ropivacaine and its current place as a local anaesthetic in otorhinolaryngology practice.

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.

Fully Awake Breast Reduction

The authors present 25 cases and an in-depth 4-minute video of fully awake aesthetic breast reduction, which was made possible by thoracic epidural anesthesia. There are obvious and important advantages to this technique. Not only does this allow for intraoperative patient cooperation (i.e., patient self-positioning and opinion for comparison of breasts), meaning a shorter and more efficient intraoperative time, there also is a reduction in postoperative pain, complications, recovery, and discharge times. The authors have also enjoyed great success and no complications with this technique in over 150 awake abdominoplasty/total body lift patients. The authors feel that the elimination of the need for general anesthesia by thoracic epidural sensorial-only anesthesia is a highly effective and efficient technique, with very few disadvantages/complications, providing advantages to both patients and surgeons.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Doubtful effect of continuous intraarticular analgesia after total knee arthroplasty: a randomized double-blind study of 200 patients

BACKGROUND AND PURPOSE

Local infiltration analgesia (LIA) is well established for effective postoperative pain relief in total knee arthroplasty (TKA). To prolong the effect of LIA, infusion pumps with local intraarticular analgesia can be used. We evaluated the effect of such an infusion pump for the first 48 h postoperatively regarding pain, knee function, length of stay (LOS) in hospital, and complications.

PATIENTS AND METHODS

200 patients received peroperative LIA and a continuous intraarticular elastomeric infusion pump set at 2 mL/h. The patients were randomized either to ropivacaine (7.5 mg/mL) or to NaCl (9 mg/mL) in the pump. Visual analog scale (VAS) pain (0-100 mm), analgesic consumption, side effects of medicine, range of motion (ROM), leg-raising ability, LOS, and complications during the first 3 months were recorded.

RESULTS

On the first postoperative day, the ropivacaine group had lower VAS pain (33 vs. 40 at 12 noon and 36 vs. 43 at 8 p.m.; p = 0.02 and 0.03, respectively), but after that all recorded variables were similar between the groups. During the first 3 months, the ropivacaine group had a greater number of superficial and deep surgical wound infections (11 patients vs. 2 patients, p = 0.02). There were no other statistically significant differences between the groups.

INTERPRETATION

Continuous intraarticular analgesia (CIAA) with ropivacaine after TKA has no relevant clinical effect on VAS pain and does not affect LOS, analgesic consumption, ROM, or leg-raising ability. There may, however, be a higher risk of wound-healing complications including deep infections.

Sufentanil modifies the antibacterial activity of bupivacaine and ropivacaine

PURPOSE

The purpose of our study was to investigate the effect on the growth of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Enterococcus faecalis (E. faecalis) of bupivacaine at a final concentration of 0.77 mg.mL(-1), ropivacaine at 1.2 mg.mL(-1), and sufentanil at 0.38 and 0.5 microg.mL(-1) (alone or in combination with bupivacaine and ropivacaine).

METHODS

The strains were diluted to approximately 3 x 10(4) cfu.mL(-1) in Mueller-Hinton broth. The anesthetics (0.5 mL) were incubated with the bacterial suspensions (0.5 mL) for 24 hr at 37 degrees C.

RESULTS

Bupivacaine inhibited the growth of E. coli (59 +/- 0.8%; P < 0.05) and S. aureus (22 +/- 3.6%; P < 0.05). Ropivacaine also inhibited the growth of E. coli (41 +/- 1.2%; P < 0.05) and S. aureus (25.5 +/- 4.1%; P < 0.05). Both anesthetics were ineffective against E. faecalis. Sufentanil only inhibited S. aureus (13.8 +/- 3.1%; P < 0.05) at a concentration of 0.5 microg.mL(-1). Sufentanil modified the antibacterial activity of bupivacaine and ropivacaine. It increased the inhibitory effect of bupivacaine on E. faecalis and S. aureus by 10 +/- 2.1% (P < 0.05) and on E. coli by 7% (P < 0.05). Sufentanil did not increase the inhibitory effect of ropivacaine on the growth of S. aureus. On the other hand, sufentanil reduced the inhibitory effect of ropivacaine on E. coli by 11% (P < 0.05).

CONCLUSION

Both bupivacaine and ropivacaine alone or combined with sufentanil inhibited the growth of E. coli and S. aureus. E. faecalis was partially sensitive to a bupivacaine + sufentanil mixture. Sufentanil had a partial synergistic effect on bupivacaine and a partial antagonistic effect on ropivacaine's antibacterial activity.

Comparison of the antibacterial activity of lidocaine 1% versus alkalinized lidocaine in vitro

BACKGROUND

Infections after epidural and spinal blocks are rare. The topical anesthetic liclocaine used in these procedures has been found to have antibacterial effects on various microorganisms.

OBJECTIVE

The aim of this study was to assess the antibacterial effects of alkalinized liclocaine on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

METHODS

Lidocaine 2%, alkalinized lidocaine, and physiologic saline (as a control solution) were added to standard bacterial preparations. The final concentration of the lidocaine was 10 mg/mL (1%). At baseline and 3 and 6 hours after incubation at 37°C, 3-mL aliquots were vortexed and pipetted into sterile polystyrene spectrophotometer cuvettes. Baseline referred to the end of the period of preparation of the solution (≤20 minutes). Growth was measured as the optical density at a wavelength of 540 nm.

RESULTS

Compared with the control, lidocaine significantly inhibited the growth of S aureus, E coli, and P aeruginosa at baseline and 3 and 6 hours after incubation (all, P < 0.05). Alkalinized lidocaine significantly inhibited the growth of S aureus at baseline and 3 and 6 hours (all, P < 0.05), while it significantly inhibited the growth of E coli and P aeruginosa only at 6 hours (both, P < 0.05). The growth of E coli was significantly less in lidocaine than in alkalinized lidocaine at 0 and 3 hours (both, P < 0.05).

CONCLUSION

The antibacterial effect of lidocaine 1% on S aureus was not changed after alkalinization. The effect of alkalinized lidocaine on E coli and P aeruginosa was significant only at 6 hours. Lidocaine significantly inhibited the growth of these 3 microorganisms at all study periods.

A prospective, randomized, blinded study of continuous ropivacaine infusion in the median sternotomy incision following cardiac surgery

OBJECTIVE

The aim of this prospective, randomized, double-blind, placebo controlled trial was to evaluate the safety and efficacy of continuous ropivacaine infusion of into the sternal wound.

METHODS

We planned to enroll 200 patients scheduled for various cardiac surgical procedures into the study. Patients, in a double-blind randomized fashion, were given either normal saline or 0.3% ropivacaine through 2 subcutaneous multiport catheters placed on either side of the sternal split at an infusion rate of 4 mL/h for 64 hours. The efficacy outcomes measured were time to extubation of the trachea, intensive care unit and hospital stay duration, pain scores, and narcotic usage. The safety outcomes measured were systemic local anesthetic toxicity, major cardiac complications, and wound infection.

MEASUREMENTS AND MAIN RESULTS

The data safety monitoring board stopped the study after enrolling 85 patients because of excessive sternal wound infections (9%, n = 44) in the ropivacaine group. This rate of infection was not statistically different from the control group (0%, n = 41, P = 0.12), but it was statistically different from our historical incidence of sternal wound infection (1.9%, no = 6381, P = 0.002). There was also a lack of evidence of efficacy for time to extubation of the trachea, narcotic usage, and pain control.

CONCLUSIONS

The phase III trial did not show improvement in time to extubation of the trachea or pain control in the 0.3% ropivacaine group, but it was stopped early by the data safety monitoring board.

Ropivacaine: A review of its pharmacology and clinical use

Ropivacaine is a long-acting amide local anaesthetic agent and first produced as a pure enantiomer. It produces effects similar to other local anaesthetics via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is less lipophilic than bupivacaine and is less likely to penetrate large myelinated motor fibres, resulting in a relatively reduced motor blockade. Thus, ropivacaine has a greater degree of motor sensory differentiation, which could be useful when motor blockade is undesirable. The reduced lipophilicity is also associated with decreased potential for central nervous system toxicity and cardiotoxicity. The drug displays linear and dose proportional pharmacokinetics (up to 80 mg administered intravenously). It is metabolised extensively in the liver and excreted in urine. The present article details the clinical applications of ropivacaine and its current place as a local anaesthetic in the group.

Local anesthetics as antimicrobial agents: a review

BACKGROUND

Since the introduction of cocaine in 1884, local anesthetics have been used as a mainstay of pain management. However, numerous studies over the past several decades have elucidated the supplemental role of local anesthetics as antimicrobial agents. In addition to their anesthetic properties, medications such as bupivacaine and lidocaine have been shown to exhibit bacteriostatic, bactericidal, fungistatic, and fungicidal properties against a wide spectrum of microorganisms.

METHODS

A comprehensive literature search was conducted using MEDLINE 1950-present for in vitro and in vivo studies pertaining to the antimicrobial activity of various local anesthetics on a broad range of bacterial and fungal pathogens. Studies testing the effect on microbial growth inhibition of local anesthetics alone and in combination with other agents, such as preservatives and other medications, as well as the effect of conditions such as concentration and temperature, were included for review. Outcome measures included colony counts, area-under-the-curve and time-kill curve calculations, minimum inhibitory concentrations, and post-antibiotic effect.

RESULTS

Evidence suggests that local anesthetics as a class possess inherent antimicrobial properties against a wide spectrum of human pathogens. Multiple local anesthetics at concentrations typically used in the clinical setting (e.g., bupivacaine 0.125%-0.75%; lidocaine 1%-3%) inhibit the growth of numerous bacteria and fungi under various conditions. Different local anesthetics showed various degrees of antimicrobial capacity; bupivacaine and lidocaine, for example, inhibit growth to a significantly greater extent than does ropivacaine. Greater concentrations, longer exposure, and higher temperature each correlate with a proportional increase in microbial growth inhibition. Addition of other agents to the anesthetic solutions, such as preservatives, opioids, or intravenous anesthetics such as propofol, modify the antimicrobial activity via either synergistic or antagonistic action. Limited studies attribute the mechanism of action of antimicrobial activity of local anesthetics to a disruption of microbial cell membrane permeability, leading to leakage of cellular components and subsequent cell lysis.

CONCLUSIONS

Local anesthetics not only serve as agents for pain control, but possess antimicrobial activity as well. In such a capacity, local anesthetics can be considered as an adjunct to traditional antimicrobial use in the clinical or laboratory setting. Additionally, caution should be exercised when administering local anesthetics prior to diagnostic procedures in which culture specimens are to be obtained, as the antimicrobial activity of the local anesthetic could lead to false-negative results or suboptimal culture yields.

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.

Ropivacaine: a review of its use in regional anaesthesia and acute pain management

Ropivacaine (Naropin) is the pure S(-)-enantiomer of propivacaine, and is a long-acting amide local anaesthetic agent, eliciting nerve block via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is a well tolerated regional anaesthetic effective for surgical anaesthesia as well as the relief of postoperative and labour pain. The efficacy of ropivacaine is similar to that of bupivacaine and levobupivacaine for peripheral nerve blocks and, although it may be slightly less potent than bupivacaine when administered epidurally or intrathecally, equi-effective doses have been established. Clinically adequate doses of ropivacaine appear to be associated with a lower incidence or grade of motor block than bupivacaine. Thus ropivacaine, with its efficacy, lower propensity for motor block and reduced potential for CNS toxicity and cardiotoxicity, appears to be an important option for regional anaesthesia and for the management of postoperative and labour pain.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.

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.

Regional anaesthesia, local anaesthetics and the surgical stress response

Epidural anaesthesia has the potential to improve patients' outcome after major surgical procedures by reducing postoperative morbidity and duration of recovery. Possible benefits include the attenuation of cardiac complications, an earlier return of gastrointestinal function associated with an increase in patients' comfort overall, decreased incidence of pulmonary dysfunction, beneficial effects on the coagulation system and a reduction in the inflammatory response. The underlying mechanisms, however, remain unclear. Since local anaesthetics (LAs), reabsorbed from the epidural space, seem to contribute to these effects, it is not easy to differentiate between the systemic effects of LAs and the effects of neuraxial blockade by epidural anaesthesia. Thus, in patients not able or willing to receive intra- and/or postoperative epidural analgesia, systemic administration of LAs may be considered to be a new therapeutic approach for the prevention of postoperative disorders by modulation of the peri- and postoperative inflammatory.

["Alternative" effects of local anesthetic agents]

The following article summarizes different aspects of local anesthetic effects that cannot be explained purely by a sodium channel blockade. Particularly remarkable is hereby their antiinflammatory activity, e.g. the inhibition of pathological changes such as excessive stimulation of the inflammatory system, without compromising the host defense system. In contrast to other immunosuppressive drugs commonly used for treating such conditions, local anesthetics look promising for the future as a new therapeutic option. Besides general anesthetic activity, local anesthetics exert cerebroprotective effects and are furthermore, in consideration of their cardiovascular stability, of interest during neuroanesthetic procedures. In addition, local anesthetics are known for their potency to minimize bronchial hyperreactivity, although details of the underlying mechanisms are not yet elucidated. These effects of local anesthetics may represent interesting prospects for which their relevance has to be determined.

Ropivacaine 0.1% with sufentanil 1 microg/mL inhibits in vitro growth of Pseudomonas aeruginosa and does not promote multiplication of Staphylococcus aureus

We investigated the effect of ropivacaine combined with sufentanil, a mixture frequently used for postoperative epidural analgesia, on the growth of Staphylococcus aureus and Pseudomonas aeruginosa at room temperature. Aliquots of suspension of S. aureus and P. aeruginosa in saline were transferred into test tubes containing either a mixture of ropivacaine 0.1% and sufentanil 1 microg/mL (R+S) or saline (SA), with the latter serving as control. At 0, 3, 6, 24, and 48 h after inoculation, 1 mL of each solution was spread over standard blood agar. The plates were incubated at 22 degrees C for 48 h, and the numbers of colony-forming units (cfu) were counted. The growth ratio for both bacterial strains was calculated as cfu time (t(n))/cfu baseline (t(0)). The primary efficacy variable was the area under the curve (AUC) in (cfu t(n)/cfu t(0)) x time, based on the growth ratios. The AUC for P. aeruginosa was significantly less in R+S than in SA (P = 0.028). Multiplication of P. aeruginosa (growth ratio >1) was observed for at least 6 h after inoculation in SA. Growth of P. aeruginosa was significantly less in R+S than in SA at 3 h (P = 0.043) and 24 h (P = 0.012) after inoculation. The AUC for S. aureus did not differ significantly between R+S and SA (P = 0.74). Neither R+S nor SA promoted multiplication of S. aureus. Forty-eight hours after inoculation, growth of S. aureus was significantly less in R+S than in SA (P < 0.0001). We conclude that R+S inhibited growth of P. aeruginosa and did not promote multiplication of S. aureus when compared with SA.

IMPLICATIONS

This laboratory study demonstrated that compared with saline, ropivacaine 0.1% with 1 microg/mL of sufentanil inhibited growth of Pseudomonas aeruginosa and did not promote multiplication of Staphylococcus aureus at room temperature. With respect to bacterial infection with these two strains, the mixture seems to be safe for continuous epidural administration if prepared under aseptic conditions and after alcohol hand rub.