domingo, septiembre 12, 2010
Finalmente ha salido publicado el estudio irlandes que compara el Ulmo chileno y la Manuka neozelandeza, con un desafio antimicrobial con bacterias resistentes al methicillin, la conclusión es que el Ulmo sería más efectivo que la Manuka en el control de Staphylococcus aureus, Escherichia coli y Pseudomonas aeruginosa.
From the results contained in this report we conclude that, due to its high antimicrobial activity, Ulmo 90 may warrant further investigation into its use as a possible alternative therapy for wound healing.
Pero lo bonito no esta ahí. Lo bonito está en lo relativo y en lo cosmético.
La miel de manuka se clasifica de acuerdo al factor UMF. La manuka utilizada en el estudio era de mediana concentración con +25.
El Ulmo no está sujeto a esta clasificación ya que no contiene el UMF, que de acuerdo a la información publicada sería methylglyoxal, no obstante la controversia y desvinculación del Dr. Molan con el UMF/MGO.
Me imagino a nivel cosmético señalan los doctores irlandeses al Ulmo como 90. Lo primero que viene a la mente es que ambos, el +25 y el 90, serían unidades de la misma escala.
Asi no sería de extrañar que el 90 le gane al +25, por un factor de cerca de 4.
El 90 del Ulmo proviene del estudio polínico realizado por la PUC, indicando que al menos el 90% del polen que contenía la muestra analizada era de Eucriptia cordifolia (Ulmo).
También por "acto de fé", asignamos la misma distribución a la composición de la miel. 90% sería néctar de Ulmo.
En el caso de la manuka el MGO aumenta con el tiempo.
The in vitro antibacterial activity of Ulmo 90 and manuka honey was evaluated
and compared. Data obtained from the agar diffusion and spectrometric assays has
demonstrated, for the first time, that Ulmo 90 honey exhibits a stronger peroxide
attributable antimicrobial effect against five out of seven bacterial isolates tested
compared with manuka honey. Using the agar diffusion method, on average, Ulmo honey
displayed larger zones of inhibition against all MRSA strains. However, in some cases,
large standard deviations were observed (Table 1). This may be accounted for by the
method used to inoculate the bacteria on to the surface of the agar. Although this method
has been used in previous studies , a more precise method may be to seed the agar
with the test organism as described by Allen et al. (1991) .
A lower MIC was observed for Ulmo 90 honey (3.1% - 6.3% v/v) in comparison
to manuka (12.5% v/v) for all five MRSA strains. Although this difference, which is one
dilution, may not be significant. A previous report , showed that the MBC from
Medihoney (contains manuka honey) against MRSA was 3% while ours was 3.1% v/v for
Ulmo 90 for 3 of the 5 strains and 6.3% v/v for the other two. That previous report  proposed that there are differences in the susceptibility of strains of the same species,
which we have confirmed for MRSA isolates. The MIC values for manuka honey may
seem high (12.5%), especially when compared to Patton et al. (2006) , where the same spectrophotometric assay was used. That study used a less potent manuka honey
(UMF 18+) with a resulting MIC of 6.25% v/v. However, the differences observed
between that study and the current study may explain this anomaly, e.g. a different strain
of S. aureus was used in that study.
The removal of hydrogen peroxide activity from Ulmo 90 was shown to have
reduced its antimicrobial activity. A 25% v/v solution of the Ulmo 90 had no detectable
antibacterial activity when tested in the presence of catalase, where previously a 3.1% v/v
solution of Ulmo honey was both the MIC and MBC for MRSA strain 0791. This would
suggest that bacterial inhibition in the previous experiments was mainly due to hydrogen
peroxide generation. Although some activity was observed in Ulmo 90 at 50% v/v
concentration, the same activity was seen in the laboratory synthesised honey, which may
indicate that activity at this concentration may be due to other factors such as osmotic
pressure or high sugar content. In contrast, while the MIC and MBC was affected, a 25%
v/v solution of manuka displayed antibacterial activity in the presence of catalase i.e. this
was the dilution at which both MIC and MBC was observed on the removal of peroxide
activity. This finding was expected for manuka as it has been previously shown that its
antibacterial activity is attributed to non-peroxide components such as MGO . As
catalase is present in body tissues, this may have an effect on the in vivo activity of
hydrogen peroxide-dependent honeys. However the extent of this effect is not known.
Similar to other studies, this paper presents the findings of in vitro antibacterial
activity of a honey against planktonic bacteria and therefore results cannot be
extrapolated to the chronic wound environment. The chronic wound harbours up to four
different wound pathogens  and indeed the presence of bacterial wound biofilms compound the difficulties in understanding and managing such an environment .
Within the biofilm, the characteristics of the bacteria change, so that biofilm-embedded
bacteria are up to 1000 times more resistant to antibiotics than the ‘planktonic’ bacteria
that are used to test antibiotic sensitivity . The antibacterial nature of honey is
dependent on various factors working either singularly or synergistically, the most salient
of which are; hydrogen peroxide (produced by the glucose oxidase added to honey by
bees), phenolic compounds, wound pH, pH of honey; osmotic pressure exerted by the
honey, cleansing of the wound bed by the honey, level of exudate and the frequency of
application. The degree to which any one of these contribute to in vivo antimicrobial
efficacy has yet to be determined. However, a recent study examining the antimicrobial
properties of honey in vitro found that hydrogen peroxide, MGO and an antimicrobial
peptide, bee defensin-1, were distinct mechanisms involved in the bactericidal activity of
honey . In addition to its antimicrobial properties, the effects of honey on host cells
may also play an important role in wound healing [17, 18]. Therefore to focus solely on
peroxide in honey limits our understanding of how honey may contribute to managing the
bacterial wound bioburden.