الفهرس 
Gram Negative BacilliOnly 14 pages are availabe for public view
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Abstract
The role of the microbiology laboratory in the diagnosis and monitoring of infections is extensive and comprises a significant part of the daily workload. The gold standard for the diagnosis is the conventional culture of samples on solid media. Presumptive identification of pathogens and detection of mixed cultures on such media can be difficult, time consuming and requires experience. The development of media which utilize various chromogenic substrates has made the process of interpreting urine cultures easier and faster (Sekikawa et al., 2011).
Chromogenic media incorporate chromogenic enzyme substrates which allow for the detection of bacterial enzymes glucosidase (GLU), galactosidase (GAL) and tryptophan deaminase (TDA). Utilization of these substrates results in the development of unique coloured colonies (Sekikawa et al., 2011).
The aim of the present study is to evaluate the performance of two chromogenic media; chrOMagar Orientation and Uriselect4 media; compared with conventional culture media.
The study was carried out on 100 gram negative bacilli specimens from 37 urine and 63 pus specimens (excluding contaminated specimens, Candida and those yielding no growth or yielding pure gram positive organisms) referred to Microbiology Laboratory of the Main Laboratories of Ain Shams University Hospitals for routine culture and sensitivity.
1) All specimens were subjected to:
a) Culture on conventional media (blood &MacConkey agar).
b) Culture on chrOMagar Orientation medium (CHROMagar
Company, Paris, France®).
c) Culture on Uriselect4 medium (US, Bio Rad laboratories®).
2) All culture plates were incubated and evaluated for bacterial growth.
3) All growth was identified by Conventional methods.
4) All data were tabulated and statistically analyzed.
The study included 100 specimens of which 37 urine and 63 pus that were cultured on conventional media (BA/MAC) and chromogenic media (CO & US) and the confirmation was done by conventional biochemical reactions and API 20 E system.
A total of 210 clinically significant organisms were isolated. The number of organisms which were isolated and identified correctly by BA/MA, CO and US was 144 (68.57%), 206 (98%) and 188 (89.52%) respectively.
The number of gram negative bacilli which were isolated and identified by BA/MAC, CO and US was 133 (78.43%) 174 (100%) and 157 (90.22%) respectively.
The chromogenic media (CO & US) were able to identify gram negative isolates on first day compared to conventional media.
CHROMagar was better in detection of mixed growth, US in detection of two isolate growths and BA/MAC was better in detection of pure growth.