The Evaluation of Chromogenic CPS ID2 Medium in the Identification of Bacterial Isolates
Flora Infeksiyon Hastalıkları ve Klinik Mikrobiyoloji Dergisi
CPS ID2 is a chromogenic medium defined for the urinary specimens. The final products with different colours produced by the bacterial enzymatic degradation of the chromogenic substrates within the medium make it possible for bacterial colonies to be identified in terms of colony colour. In this study we aimed to evaluate the use of CPS ID2 medium in defining pre-identified, clinical bacterial isolates in terms of the colony colour they produce in the media. Suspensions in sterile physiological
... saline corresponding to a colony count of 108 CFU/mL of bacteriae were prepared with a total of 423 bacterial isolates from various clinical specimens all of which were inoculated to blood agar or EMB and CPS ID2 media. Bacterial identification using colony colour on chromogenic media was compared with the identification made by conventional tests. The quality control of the media was performed using Escherichia coli ATCC 27853 and Enterococcus faecalis ATCC 29212. A total of 79 (95.2%) E. coli out of 83 created typical pink-dark red coloured colonies whereas 4 (4.8%) grew as transparent without creating any colour. Proteus (n: 11), Morganella (n: 4), Providencia (n: 1) (PMP) produced translucent colonies with a brown hue around. Klebsiella (n: 60), Enterobacter (n: 43), Serratia (n:10) (KES) were recognised as metallic, blue-green, large colonies, also defined as having a turquoise colour. Yet a small number of tests needed to be planned in order for bacteria included in PMP and KES groups to be defined in species level. All enterococci (n: 55) were readily identified by the small, blue-green, turquoise colonies. In the rest of the bacterial groups colony colour did not provide adequate information for bacterial identification. Except for one group A and one group C streptococci no failure of isolation was observed with the media under test.