Initial study of three different pathogenic microorganisms by gas chromatography-mass spectrometry.

Background: Diagnoses  of  respiratory  tract  infections  usually happen  in the  late  phase  of  the  disease  and  usually  result  in  reduction  of  the pathogen  load after broad-spectrum  antibiotic  therapy,  but  not  in eradication of the pathogen.  The  development  of a  non-invasive,  fast,  and accurate  method  to  detect  pathogens  has  always  been  of  interest  to researchers  and  clinicians  alike.  Previous studies have shown that bacteria produce organic gases.  The  current  study  aimed  to  identify  the  volatile organic  compounds  (VOCs)  produced  by three  respiratory  tract  pathogens, including  Staphylococcus  aureus,  Escherichia  coli  and  Candida albicans.Methods: The  VOCs  produced  were identified by gas chromatography-mass spectrometry (GC-MS), with  prior  collection  of  microbial  volatile compounds  using  solid  phase  microextraction  (SPME)  fiber.  The volatile compounds were collected by obtaining bacterial headspace samples. Results: Results  showed  that  these  three  organisms  have  various  VOCs,  which were  analyzed  under  different  conditions.  By ignoring common VOCs, some species-specific VOCs could be detected.  The most important VOC of E. coli was indole, also some important VOCs produced by S. aureus  were 2,3-pentandione, cis-dihydro-α-terpinyl  acetate,  1-decyne,  1,3-heptadiene,  2,5-dimethyl pyrazine,  ethyl  butanoate  and  cyclohexene,4-ethenyl. Furthermore,  most  of the identified  compounds  by  C.  albicans are  alcohols. Conclusions: The  detection  of  VOCs  produced  by  infectious  agents  maybe  the  key  to make   a  rapid  and  precise  diagnosis  of  infection,  but  more comprehensive  studies  must  be  conducted  in this  regard.