Determination of extended-spectrum beta-lactamase (ESBL) enzyme types in ESBL positive E. coli strains which were isolated from urine samples, by using Isoelectric focusing method and Polymerase chain reaction

Extended-spectrum beta-lactamase (ESBL) enzymes are increasing through the world, commonly found in clinical isolates, easily spread out by plasmids, cause serious clinical problems and difficult to determine by routine antimicrobial susceptibility tests; these enzymes must be detected by the special tests. The aim of this study is to determine ESBL enzyme types during the period of April 2004-March 2005 at Akdeniz University Hospital Central Laboratory by using isoelectric focusing method and polymerase chain reaction (PCR) in 56 E. coli strains which were isolated from urine samples and determined as GSBL positive with the phenotypic screening tests. By the isoelectric focusing results, the transconjugant enzyme extracts produced 1 to 3 different bands, mostly at the isoelectric points of 8.0-8.4 (78.5%) and 5.0-5.4 (50%). Using PCR, it is found that of the isolates 92.8% included CTX-M, 64.2% included TEM, 10.7% included SHV and 51.7% both of the CTX-M and TEM genes. By using IEF method, 43 isolates having CTX-M, TEM and SHV enzyme bands and 11 isolates having no enzyme bands, include one or more enzyme genes with PCR methods. Genes encoding ESBL's are usually located on transferable plasmids that may also carry other resistance determinants. Therefore; detection of beta-lactamase enzyme types in ESBL positive bacteria, is important for choosing the appropriate antimicrobial agents.