The increase of the antimycotic effect of nystatin on Aspergillus species due to microbial exoenzymes

Ref ID: 19584

Author:

NP Sachivkina1*

Author address:

1Microbology, People’s Friendship University of Russia, Moscow, Russia

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
While previously rarely considered to be the cause of infections, Aspergillus species are now known
to be the major cause of disease and mortality in immunocompromised patients. Most clinical strains
of fungi are able to demonstrate resistance to antimycotic medications. Given the significance of
invasive aspergillosis in healthcare, this study aims to assess the effects of lyticase on fungi of
Aspergillus fumigatus species in combination with antifungal medication.
Methods:
Lyticase is an exoenzyme produced by soil bacteria that is able to cleave the mannoprotein complex of
fungal cell walls. Previously we had shown that lyticase successfully causes cell wall lysis of Candida
and enhances the effects of various antifungal agents by several times [ Sachivkina et al., 2013 ]. In
this investigation, the object of study is the pathogenic strain of fungi Aspergillus fumigatus, isolated
from the lung of a dead animal (dog) in the veterinary clinic, as well as widely known antimycotic
drug nystatin 25,000 units. The enzyme lyticase was obtained from culture broth of Cellulomonas
cellulans AS- 870 strain, which is stored in the National Collection of Microorganisms of the State
Research Institute of Genetics and Selection of Industrial Microorganisms. The already-ready
enzyme Lyticase 20,000 units («Sigma», Germany) could have also been used in the experiment,
but the product yielded by our technology exceeded the specific activity of commercial drug.
Aspergillus sp. grow well on standard nutrient media, which is why the liquid medium Saburo was
used. Titration of the antimycotic drug Nystatin was carried out on a microplate in liquid medium
at different concentrations, decreasing by two times from well to well. Equal concentrations of
Aspergillus was seeded in row A, which initially contained the concentration of 2500 IU of nystatin.
Lyticase was added to row B in a concetration ratio of 1:1, containing the same nystatin titer.
Analougus with this set-up, row C contained 250 units of nystatin, and row D contained 250 unitis
of nystatin with the addition of 250 IU of the enzyme lyticase in a 1:1 ratio. Aspergillus was seeded
in all rows equally. After 5 days, the results were obtained. A seeding was carried out onto a dense
Saburo medium from the microplate.
Results:
On the fifth day the following results were obtained from the microplate: row A had no growth in
the 4th well (at a concentration of 156,25 IU of nystatin), growth retardation was noted in well A5
(78,125 units). Row B (with the addition of lyticase) showed a full halt in growth in well 6 (39.06
IU of nystatin), growth retardation was observed from B7 (19,53 IU) to B11 (1,22 IU). In row C
with the intitial concentration of 250 units, a full stop was observed in well C1 (125 IU), stunted
growth was noted in wells from C2 (62,5 IU) to C3 (31,3 IU). A halt of growth was observed in
row D starting from well D3 (31,3 IU), growth retardation was seen in wells D4 (15 , 6 IU) to D10
(0,24 IU). Moreover, the prevelance of mycelial growth over the growth of the sporangium in rows
with lyticase was noted. After seeding on the solid medium, an offset of fungal growth was noted.
Complete cessation of growth occurred in wells A3 (312.5 IU), B5 (78,125 IU), D2 (62,5 IU). Based
on these results, we found that the enzyme lyticase increases the effect of the antimycotic medication
by four times.
Conclusion:
The results obtained in this study could shape future treatment plans of patients suffering from fungal
infections, by potentially untilizing combined therapy with lyticase as to significantly reduce the risk
of side effects, which are a substantial drawback of almost all modern antifungal medications. Such
combined therapy would considerably improve the treatment of patients at risk of an Aspergillus
infection.

Abstract Number: 109

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

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