Novel Chemotherapy Targeted at Candida glabrata

1
Novel Chemotherapy Targeted at Candida glabrata
Brenda Ormesher, MD Richard Calderone, PhD
Department of Medicine, Georgetown University
Hospital, Washington, DC Georgetown University
Medical Center, Washington, DC
Georgetown University
Abstract
Results
Approximately 60 compounds had MIC testing done
against Candida glabrata wild type strain. From
the panel seven compounds demonstrated good
activity against wild type glabrata. Based on a
molecular weight of 300 an MIC50 of 50 mmol
equates to 15 mg/L and 10 umol equates to 3mg/L.
Although 90 of the agents tested did not
demonstrate high inhibitory activity at 24 or
48hrs the 7 agents with MIC of less than 50mmol
did show some promise. In the figures to the
right graphical representation of the promising
compounds is demonstrated compared to a control
of fluconazole.
Figures
Introduction Recently Candida glabrata has
become an important pathogen in our healthcare
system especially in the immunocompromised
patients. Given its decreased sensitivity to
azoles more chemotherapeutic agents are needed to
treat these infections. Methods Candida
glabrata wild type BG2 was tested using NCCLS
guidelines for MIC to novel chemotherapeutic
drugs provided by Dr. Groteus laboratory. Results
Approximately 60 compounds from Dr. Bill Groteus
laboratory had MIC testing done on C. glabrata
BG2. Seven of these compounds had MIC values of
50mL at 24 hours with potential for further
studies. Conclusions Early results for MIC
testing of the panel compounds demonstrate that
with additional manipulation of these drugs new
agents may be available to use in our clinics.
B
A
Fig. 1(A-B). Sample results from MIC testing at
24 hrs. Plates were read at 630nm with
spectrometer.
Fig. 2. MIC50 of sample chemotherapeutic agents.
Introduction
C. glabrata is an important pathogen affecting
our immunocompromised patients including those
with HIV and cancer patients currently on
chemotherapy. Most common sites of infection
include corneal, cardiac (endocarditis), vaginal,
oral and disseminated forms. Glabrata is the
second most common form of disseminated
candidiasis only after C. albicans. Candida
glabrata is known for its decreased sensitivity
to azoles thought to be related to increased drug
efflux. This makes treatment of glabrata more
difficult. Given the high MIC patterns of most
chemotherapeutic to C. glabrata, Amphotericin B
is currently the gold standard.
Fig. 3. Sample structure representations of
compounds tested.
Conclusions
Given the increased prevalence of Candida
glabrata in our patient population it is
important to continue to develop chemotherapeutic
agents to combat this growing problem. More
research is needed to further develop new drugs
and improve treatment of fungal infections.
Discussion
Initial results demonstrated some potential
compounds that may be further used to develop
novel chemotherapeutic agents. These agents need
further testing on various glabrata subspecies
and other candidial species. These compounds can
also be used to determine structure- function
capabilities to further our understanding of
drug- microbe interaction. Although the initial
compounds did not demonstrate the same activity
against C. glabrata as the current gold standard
for treatment of Amphotericin B (MIC50 at 24hrs
was reported to be 0.5-4 mg/L) the potential for
further chemical manipulation to increase
activity is a viable option. Further studies
need to be done to continue to develop our
arsenal of treatments available to combat Candida
infections.
Methods
Isolates Wild type isolates for MIC testing were
obtained from stock culture from Dr. Calderones
laboratory. Originally BG14 strain was selected
for use in MIC testing but did not grow
adequately in 96 well plates and BG2 was
substituted. Antimicrobial Susceptibility
Testing MICs were measured by the NCCLS broth
microdilution method. C. glabrata BG2 isolates
were grown overnight in tryptone soya broth
supplemented with 0.5 yeast extract (TSBYE).
Inoculum size was 5x104 cfu and the volume per
well was 100 mL. Each well was mixed with 100 ml
of a set dilution of novel drug. Plates were
covered and incubated at 38oC in 5 CO2
incubator. Plates were read at 24 and 48 hours
incubation at 630nm spectrometer for data
collection. Novel compounds used in MIC testing
were supplied by Bill Grouteas, PhD (Wichita
State University).
References

• National Committee for Clinical Laboratory
  Standards. (2000). Methods for Dilution
  Antimicrobial Susceptibility Tests for Bacteria
  That Grow AerobicallyFifth Edition Approved
  Standard M7-A5. NCCLS, Wayne, PA, USA.
• Parkinson, T Falconer, DJ Hitchcock, CA.
  Fluconazole resistance due to energy-dependent
  drug efflux in Candida glabrata. Antimicrobial
  Agents and Chemotherapy, Aug 1995, 1696-1699, Vol
  39, No. 8.
• Huseyin, A. Sancak, B. Arikan, S. In vitro
  activity of amphotericin B, fluconazole and
  itraconazole against Candida glabrata strains
  isolated from clinical samples. Mikrobiyol Bul.
  2007 Apr 41 (2) 235-44.

Acknowledgments Thank you to Dr. Calderones lab
including Neeraj Deepu