Clinically significant concentrations of local anesthetics inhibit Staphylococcus aureus in vitro

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.

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.

Neurological infections after neuraxial anesthesia

Infection is the commonest cause of serious neurologic sequelae of neuraxial anesthesia. The incidence depends on operator skill and patient population. Meningitis, a complication of dural puncture, is usually caused by viridans streptococci. The risk factors are dural puncture during labor, no mask and poor aseptic technique, vaginal infection and bacteremia. Epidural abscess is a complication of epidural catheterization, route of entry the catheter track and the organism usually the staphylococcus. Principal risk factors are prolonged catheterization, poor aseptic technique and traumatic insertion. Prevention includes wearing a mask, using a full sterile technique, avoiding prolonged catheterization and prescribing antibiotics in a high-risk situation.

Intrathecal baclofen does not inhibit the growth of different bacterial species and Candida albicans

BACKGROUND

The antimicrobial activity of intrathecal baclofen was investigated. Several different microorganisms were used: Staphylococcus aureus (beta-lactamase-positive and beta-lactamase-negative strains); S epidermidis; Enterococcus faecalis; Klebsiella pneumoniae; Escherichia coli; Pseudomonas aeruginosa; and Candida albicans.

METHODS

Three experimental approaches were used to assess baclofen antimicrobial activity: (1) determination of the MIC; (2) determination of the MBC; and (3) kinetic time-kill assay. Experiments were performed according to current methods of the NCCLS.

RESULTS

As compared with control organisms exposed to physiologic saline, organisms exposed to baclofen over a 10-day period failed to reduce the number of viable cells by at least 3 log(10), as requested by NCCLS criteria.

CONCLUSIONS

Because the viability of the investigated organisms was not reduced over that of microbial suspensions exposed to physiologic saline, we conclude that intrathecal baclofen has no measurable activity against different bacterial species and C albicans.

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.