Local Anesthetic anti-bacterial activity
(Ropivacaine has a Poor antibacterial effect in comparison with Bupivacaine)
Joseph Eldor, MD
is a long-acting local anaesthetic and analgesic,
used for surgical anaesthesia and acute pain management (post-operative pain management and labour pain). First launched in 1996, Naropin
is the world's first enantiomerically pure local anaesthetic (an S-form enantiomer),
and is now available in over 30 countries, including the
Naropin® solution for injection is a sterile, isotonic, aqueous solution. The pH of the solution is adjusted with sodium hydroxide or hydrochloric acid and the solution is free from preservatives.
At the AstraZeneca Prescribing Information under “Undesirable effects” is written:
The adverse event profile of Naropin® is similar to that of other long-acting local anesthetics of the amide-type.
Adverse reactions to local anesthetics are very rare in the absence of overdose or inadvertent intravascular injection. They should be distinguished from the physiological effects of the nerve block itself, e.g. a decrease in blood pressure and bradycardia during epidural anaesthesia. The effects of systemic overdose and inadvertent intravascular injections can be serious (see "Overdosage").”
However, it seems that the statement “The adverse event profile of Naropin® is similar to that of other long-acting local anesthetics of the amide-type.” has to be rewritten related to the anti-bacterial activity of Ropivacaine Vs. Bupivacaine.
Based on the following survey it is concluded that : Ropivacaine has a Poor antibacterial effect in comparison with Bupivacaine.
Since Ropivacaine is now frequently used for epidural anesthesia and analgesia as well as for wound analgesia infiltration and peripheral nerve blocks this “unrecognized” poor antibacterial effect has a very important implication on its use.
Rosenberg PH and Renkonen OV (1) examined the antimicrobial activity of bupivacaine and morphine against 10 microbial strains with an agar dilution method. The strains tested were Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), and one of each of the clinical isolates of Staphylococcus epidermidis (a multiresistant strain), Staphylococcus epidermidis (a sensitive strain), Streptococcus pneumoniae, Streptococcus pyogenes (A), Streptococcus faecalis, Bacillus cereus, and Candida albicans. The antimicrobial effect of bupivacaine was tested at concentrations of 0.5, 1.25, 2.5, and 5 mg/ml (0.05% 0.125%, 0.25%, and 0.5%). Bupivacaine at a concentration of 2.5 mg/ml inhibited the growth of the sensitive S. epidermidis strain, S. pyogenes, and S. pneumoniae, and all of the others except P. aeruginosa at a concentration of 5 mg/ml. Morphine 0.2 and 2 mg/ml (0.02 and 0.2%) did not inhibit any of the strains.
James FM et al. (2) studied the incidence of contamination of catheters and syringes used during epidural analgesia for parturients and the effectiveness of bacterial filters. The effect of bupivacaine on bacterial viability and growth was also studied. Syringes in 5/101 cases were contaminated, while catheter tips located in the epidural space were sterile. Organisms isolated were skin commensals and probably originated on the hands of anesthetic personnel. Bupivacaine (0.25%) was bacteriocidal to S epidermidis and Corynebacterium spp at 37C but not at room temperature. These findings illustrate the efficacy of using bacterial filters during continuous epidural analgesia. New syringes should be used for each epidural injection as insurance against seeding of bacteria in the presence of a defective filter.
Noda H et al. (3) studied the antibacterial activity of local anesthetics quantitatively, by procuring their minimum inhibitory concentration (MIC), killing curves and postantibiotic effect (PAE), using the standard colony of Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 14990 and Pseudomonas aeruginosa NCTC 10490. Both bupivacaine and lidocaine had bactericidal activity at a clinical concentration. MIC of the former was lower than that of the latter, and it means that bupivacaine has a greater antibacterial activity than lidocaine. At the same concentration, the commercial solutions, such as Xylocaine and Marcain, which contain preservatives, showed a greater antibacterial activity than the pure anesthetic solutions which contain no preservatives. However, the preservatives had no bactericidal activity, but weak bacteriostatic activity.
Grimmond TR and Brownridge P (4) studied the antimicrobial activity of bupivacaine and pethidine in concentrations commonly used in epidural practice by an agar dilution method against ten common micro-organisms. Both drugs showed increasing microbe inhibition with increasing drug concentrations. Bupivacaine at common epidural concentrations inhibited eight of the ten organisms and pethidine inhibited six. These findings confirm previous reports of microbe inhibition by bupivacaine, and in addition demonstrate a similar but slightly lesser activity by pethidine.
Feldman JM et al. (5) found that local anesthetics inhibit bacteria growth in culture although this effect diminishes as the concentration of the drug is reduced. Potential bacteria pathogens were cultured in agar media containing: agar alone, 2%, 1.5%, and 1% lidocaine, 0.5%, 0.25%, and 0.125% bupivacaine, 0.125% bupivacaine + fentanyl 2 mcgs/mL, 0.125% bupivacaine + sufentanil 0.3 mcgs/mL, and fentanyl 5 mcgs/mL, fentanyl 2 mcgs/mL or sufentanil 0.3 mcgs/mL. Organisms were deemed sensitive to the study agent if no growth was apparent after incubation for 24 hours. Both lidocaine and bupivacaine significantly reduced bacteria growth at all concentrations studied compared to the growth observed in agar alone (P < .0001). This growth inhibition diminished as the concentration of local anesthetic was reduced especially for certain bacteria species for example. Staphylococcus aureus (P < .0001). Neither fentanyl nor sufentanil inhibited any bacterial growth in culture.
Fariss BL et al. (6) studied the toxicity and anesthetic properties of two anesthetic agents, bupivacaine and lidocaine. These anesthetic agents did not damage tissue defenses or invite infection in experimental animals. In addition, the pain of subdermal injection, the onset of anesthesia, and the frequency of satisfactory anesthesia in human volunteers were remarkably similar.
Sakuragi T et al. (7) investigated the rate and potency of the antimicrobial activity of 0.125%, 0.25%, and 0.5% bupivacaine, 2.0% mepivacaine and 2.0% lidocaine with preservatives, and 2.0% lidocaine without preservatives on two strains of methicillin-resistant Staphylococcus aureus. The pathogen was exposed to each local anesthetic for 1, 3, 6, 12, and 24 hours at room temperature. The inocula from these suspensions were diluted to 1:1,000 with physiological saline to inactivate the antimicrobial activity of the local anesthetics and then were cultured for 24 hours at 37 degrees C on agar plates. Lower colony counts were observed with a 3-hour or longer exposure to 0.5% bupivacaine in both strains of S. aureus (P < .05). The 3-hour exposure reduced the count by approximately 60%, the 6-hour exposure by 70%, and the 24-hour exposure by more than 99%. The bactericidal activity was lowest with 0.125% bupivacaine and 2.0% mepivacaine. Antimicrobial activity was observed shortly after exposure of S. aureus to local anesthetics and appeared to be bactericidal rather than bacteriostatic.
Pina-Vaz C et al. (8) evaluated the activity of benzydamine, lidocaine, and bupivacaine, three drugs with local anesthetic activity, against Candida albicans and non-albicans strains The minimal inhibitory concentration (MIC) was determined for 20 Candida strains (18 clinical isolates and two American Type Culture Collection strains). The fungistatic activity was studied with the fluorescent probe FUN-1 and observation under epifluorescence microscopy and flow cytometry. The fungicidal activity of the three drugs was assayed by viability counts. Membrane alterations induced in the yeast cells were evaluated by staining with propidium iodide, by quantitation of intracellular K+ leakage and by transmission electron microscopy of intact yeast cells and prepared spheroplasts. The MIC ranged from 12.5-50.0 microg/mL, 5.0-40.0 mg/mL, and 2.5-10.0 mg/mL for benzydamine, lidocaine, and bupivacaine, respectively. The inhibitory activity of these concentrations could be detected with the fluorescent probe FUN-1 after incubation for 60 minutes. A very fast fungicidal activity was shown by 0.2, 50, and 30 mg/mL of benzydamine, lidocaine, and bupivacaine, respectively. At lower concentrations, the tested drugs had a fungistatic activity, due to yeast metabolic impairment, while at higher concentrations they were fungicidal, due to direct damage to the cytoplasmic membrane.
Sakuragi T et al (9) studied the bactericidal activity of preservative-free bupivacaine on two strains of methicillin-resistant Staphylococcus aureus (MRSA), two strains of methicillin-susceptible S. aureus (MSSA), and each of Staphylococcus epidermidis and Escherichia coli. The pathogen was exposed to 0.5% bupivacaine for 1, 3, 6, 12, and 24 h at 37 degrees C and room temperature. In addition, each strain of MRSA, MSSA, and S. epidermidis was exposed to distilled water, and 0.125%, 0.25%, 0.5%, and 0.75% bupivacaine at 37 degrees C. The inocula from the suspensions were cultured for 48 h at 37 degrees C. The 1- through 24-h exposures of 4 strains of S. aureus to 0.5% bupivacaine at room temperature reduced the colony count by 21.7%, 34.7%, 51.1%, 65.6%, and 81.1%, respectively, and the exposure at 37 degrees C reduced the count by 34.1%, 50.8%, 66.3%, 94.5%, and 96.0%, respectively. The differences were significant at all exposure times (P < 0.001, respectively). No organisms grew in the strain of E. coli after 24-h exposure and in the strain of S. epidermidis after 12- and 24-h exposures at 37 degrees C. The percent change from controls in the strains of E. coli and S. epidermidis was significantly higher than that in the strains of S. aureus at all exposure times at room temperature and 37 degrees C (P < 0.0001, respectively). Higher concentrations of bupivacaine were associated with lower colony count. The preservative-free bupivacaine possessed a temperature- and concentration-dependent bactericidal activity, and S. aureus was more resistant to the bactericidal activity of bupivacaine than were S. epidermidis and E. coli.
Hodson M et al. (10) compared the antibacterial activity of bupivacaine with levobupivacaine against a range of bacteria implicated in epidural infection to determine whether any differences existed between the two drugs. Concentrations of 0.125%, 0.25% and 0.5% bupivacaine and levobupivacaine were inoculated with suspensions of either Staphylococcus epidermidis, Staphylococcus aureus or Enterococcus faecalis. After incubation, the mixtures were plated onto blood agar and colony counts were recorded after a further period of incubation. The minimum bactericidal concentration of local anaesthetic against the three bacteria studied was found to be 0.25% for bupivacaine and 0.5% for levobupivacaine showing racemic bupivacaine to have a more potent antibacterial action than levobupivacaine. This finding suggests that the dextrobupivacaine isomer of racemic bupivacaine has a more potent antibacterial action than the levobupivacaine isomer.
Sakuragi T et al. (11) studied the bactericidal activity of 0.5% bupivacaine with 0.08% methyl para-oxybenzoate and 0.02% propyl para-aminobenzoate as preservatives and of the preservatives alone at 37 degrees C and at room temperature on two strains of methicillin-resistant Staphylococcus aureus, two strains of methicillin-susceptible S. aureus, and one strain each of Staphylococcus epidermidis and Escherichia coli. The pathogen was exposed to 0.5% bupivacaine with preservatives or to the preservatives alone for 1, 3, 6, 12, and 24 hours at 37 degrees C and at room temperature. The inocula from these suspensions were cultured for 48 hours at 37 degrees C after the antimicrobial activity of bupivacaine was inactivated by 1:1,000 dilution with physiological saline. The 1- through 12-hour exposures of four strains of S. aureus to 0.5% bupivacaine with preservatives at room temperature reduced the mean colony count by 24.2%, 49.2%, 71.3%, and 89.6%, respectively, and the exposure at 37 degrees C reduced the count by 74.1%, 95.2%, 99.9%, and 99.8%, respectively. The differences for 1- through 12-hour exposures were significant (P < .001). The percentage kill in the strains of E. coli and S. epidermidis was significantly higher than that in the strains of S. aureus at all exposure times at room temperature (E. coli, P < .001; S. epidermidis, P < .0001) and at 1- and 3-hour exposures at 37 degrees C (E. coli, P < .001; S. epidermidis, P < .0001). The bactericidal activity of the preservatives was markedly lower that that of 0.5% bupivacaine with preservatives (P < .0001). It was concluded that the bactericidal activity of 0.5% bupivacaine with preservatives is stronger at body temperature than at room temperature; the bactericidal activity may be due, to a large extent, to bupivacaine rather than to the preservatives; and S. aureus is more resistant to the bactericidal activity of bupivacaine than are S. epidermidis and E. coli.
Welters ID et al. (12) studied the influence of racemic bupivacaine and its enantiomers on neutrophil phagocytic activity, oxidative burst as well as surface expression of complement and Fcgamma receptors. Venous blood was pre-incubated with different concentrations of either racemic bupivacaine, R-(+) or S-(-) bupivacaine. Fluoresceine isothiocyanate (FITC)-labeled antibodies against Fcgamma receptor III (CD16), complement receptor 1 (CD35) and complement receptor 3 (CD11b) were used to determine surface receptor expression. Phagocytic activity was measured by ingestion of FITC-labeled vital Staphylococcus aureus. Oxidative burst was determined by conversion of nonfluorescent dihydrorhodamine 123 into fluorescent rhodamine 123. Fluorescent intensity of each sample was determined by flow cytometry. Racemic bupivacaine inhibited surface receptor expression, phagocytosis, and oxidative burst in a time- and concentration-dependent manner. Although the S-(-) enantiomer exerted significantly less inhibitory action on neutrophil function compared to R-(+) and racemic bupivacaine, these effects were small compared to the overall changes. These findings suggest that bupivacaine impairs surface receptor expression and may thereby contribute to reduced phagocytic activity and oxidative burst. Enantiomer-specific effects of bupivacaine may play a minor role in the inhibition of these leukocyte functions.
Batai I et al. (14) found that Ropivacaine 10 mg/mL killed Staphylococcus aureus and Escherichia coli; however, ropivacaine 2 mg/mL supported the growth of E. coli.
Pere P et al. (15) found Poor antibacterial effect of ropivacaine in comparison with bupivacaine.
Rodrigues AA et al (16) found that the novel drug ropivacaine was less potent than the former two drugs (lidocaine and bupivacaine) related to the formation of germ tubes by Candida albicans that has been assumed as a putative virulence factor.
The study suggested that the inhibitory effect of Local Anesthetics (LAs) on germ tube formation by C. albicans is due to blockade of ionic channels, particularly calcium channels. Therefore, LAs can affect morphology and probably also the pathogenesis of C. albicans.
Morris W et al. (17) aseptically collected 201 antibacterial filters that had been used for top-ups with ropivacaine +/- sufentanil for epidural analgesia during labour. They flushed them first with 2 mL of saline and then with 2 mL of a solution containing 1.5 x 10(6) Staphylococcus epidermidis/mL. The filtrates were incubated at 37 degrees C for 72 h. Number of top-ups and duration of epidural analgesia were expressed as median (extremes). 3 (1-10) top-ups were performed for labour analgesia over a period of 6.5 h (1.8-18). After filtering, all the solutions were found to be sterile. Especially, when using Staphylococcus epidermidis solutions, bacteria were not found beyond any filter. These results suggested the integrity of the filter membrane after several boluses. No infection related to epidural analgesia was reported. They concluded that antibacterial filters provide a good protection against a potentially contaminated procedure during epidural top-ups.
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