At least 174 O and 53 H antigen types have been described however only a small subset of subset of O H combinations are associated with human disease (Table 1).

The O:H combination is referred to as a serotype. coli is typed using the O and H antigens( 18).

Classic serotyping is based on the Kauffman classification scheme where E. coli can be typed according to their somatic lipopolysaccharide (O), capsular (K), and flagellar (H ) antigens. The adoption of several molecular techniques has allowed for more rapid detection and identification of the different pathotypes ( 13).Į. It is oxidase negative, produces indole, does not ferment citrate, and demonstrates a positive methyl red test and a negative Voges-Proskauer reaction. coli is typically first identified in the microbiology laboratory as a lactose-fermenting gram-negative rod that can grow both aerobically and anaerobically, preferably at 37✬, and can be either non motile oo motile. The organism is Gram-negative bacillus from the family Enterobacteriaceae that grows readily on simple culture media with minimal nutrients glucose or glycerol is often sufficient. MICROBIOLOGY, LABORATORY DIAGNOSIS AND TYPING coli is also leading cause of neonatal meningitis ( 45). The systemic infections include bacteremia, nosocomial pneumonia, cholecystitis, cholangitis, peritonitis, cellulitis, osteomyelitis, and infectious arthritis. coli is the most common cause of urinary tract infections (UTIs) in humans ( 27), and is a leading cause of enteric infections and systemic infections ( 44). coli) while other pathotypes cause infections outside the gastrointestinal system (i.e. coli have been described that cause infections of the gastrointestinal system (i.e. The organism is also found in soil and water, usually as a result of fecal contamination. Several variants or pathotypes of E. coli comprises of non-pathogenic commensal isolates that forms part of the normal flora of humans and various animals ( 96). In humans, they are the major aerobic organism residing in the intestine, typically with around 106 to 109 colony forming units per gram of stool (96). Nine years later he noted its role as a human pathogen, and postulated that the organism was responsible for ascending urinary tract infections in young women ( 94). coli and named the organism Bacterium coli commune. In 1885 Theodor von Escherich described E.

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