Ira Sigar

Assistant Professor

Midwestern University
Chicago College of Osteopathic Medicine
College of Dental Medicine - Illinois
Department of Microbiology and Immunology
Science Hall 323-H
555 31st St.
Downers Grove, IL 60515
Office: (630) 515-6149


B.S. Biology University of Indonesia 1991
M.S. Biology Illinois Institute of Technology 1994
Ph.D. Biology Illinois Institute of Technology 2005


Comparison of in vitro Chlamydial infection under aerobic and anaerobic conditions

Chlamydiaceae are obligate intracellular bacteria that cause ocular, urogenital and respiratory infection. The course of diseases is determined by local inflammatory immune responses and the requirement of the pathogen to replicate within infected host cells. Some experiments have shown that Chlamydia adapt well to hypoxic conditions, but none have been explore under strict/obligate anaerobic condition. Therefore I am interested in characterizing the effects of anaerobic conditions on in vitro chlamydial cultures to mimic in vivo conditions during chlamydial infections.

Project I: To characterize and optimize growth of different type of cell lines under anaerobic condition that could support grow of Chlamydia. Currently we have been able to grow five types of cell lines (HeLa, Hep-2, L929, Cho and Vero) under anaerobic condition. We are comparing which cells that survive the best under the anaerobic.

Project II: To characterize Chlamydia growth under anaerobic condition. To this point we have been successfully grow three different species of Chlamydia (C. muridarum, C. trachomatis and C. pneumonia) under anaerobic condition. Further study need to be done to see if the minimum inhibition concentration and minimum bactericidal concentration is the same for Chlamydia grow under aerobic condition.

Graviola extract efficacy on oral microbes
(Collaborators:  Drs. Balbina Plotkin and Ashlesh Murthy)

The graviola fruit is found from the tropical tree Annona muricata commonly found in Brazil. Recently, studies demonstrated that graviola fruit extract (GFE) exhibits anti-cancer, anti-inflammatory, and anti-microbial properties. The oral cavity is the habitat of hundreds of different species of microbes that directly or indirectly contribute to dental caries, gingivitis, and periodontitis. Because GFE shows promise of a combined action against dental pathology, this may be a significantly important naturally occurring substance.

Project I: To determine the anti-microbial efficacy of graviola extracts on common periodontal pathogens and oral microbes. We are currently try different extraction of graviola (fruit and stem/leaf) against Streptococcus mutans, S. sobrinus, S. sanguinis, Lactobacillus acidophilus, L. casei using disk diffusion method, minimum inhibition concentration and minimum bactericidal concentration (MBC). The MBC is being validated using Time-kill studies to determine how fast the killing effect of the graviola.

Project II: To investigate the anti-microbial efficacy of graviola extracts on multidrug resistant Gram-positive and Gram-negative clinical isolates.

Selected Publications (see full PubMed results)

Plotkin, B.J., I.M.Sigar, V. Tiwari, S. and Halkyard. Herpes Simplex Virus (HSV) Modulation of Staphylococcus aureus and Candida albicans Initiation of HeLa 299 Cell-Associated Biofilm. Curr Microbiol., 72(5):529-37. 2016. 

Jasper, D., I.M.Sigar, J. Schripsema, C. Sainvil, C. Smith, V. Yeruva, R. Roger; A. Murthy,  J.  Widder and K.H. Ramsey. Genomic variant representation in a Chlamydia population is dynamic and adaptive with dependence on in vitro and in vivo passage. Pathog  Dis. 2015., 73(1):1-12. 2015.  

Sigar, I.M., J.H. Schripsema, Y. Wang, I.N. Clarke, L.T. Cutcliffe, H. M.B. Seth-Smith, N.R. Thomson, C. Bjartling, M. Unemo, K. Persson and K.H. Ramsey. Plasmid deficiency in urogenital isolates of Chlamydia trachomatis reduces infectivity and virulence in a mouse model. Pathog Dis., 70(1):61-9. 2014.

Tiwari V., E. Maus, I.M. Sigar, K.H. Ramsey and D. Shukla. Role of heparan sulfate in sexually transmitted infections. Glycobiology, 22 (11): 1402-1412. 2012.

Lee, H Y., J.H. Schripsema, I.M. Sigar, S.R. Lacy, J.N., Kasimos, C.M. Murray and K.H. Ramsey. A role for CXC chemokine receptor-2 in the pathogenesis of urogenital Chlamydia muridarum infection in mice. FEMS Immunology & Medical Microbiology. 60 (1): 49-56. 2010.