Clonal relationships among avian Escherichia coli isolates determined by enterobacterial repetitive intergenic consensus (ERIC)–PCR

Forty-nine avian Escherichia coli isolates isolated from different outbreak cases of septicemia (24 isolates), swollen head syndrome (14 isolates) and omphalitis (11 isolates), and 30 commensal isolates isolated from poultry with no signs of illness were characterized by enterobacterial repetitive intergenic consensus (ERIC)–PCR technique and their serotypes were determined. The ERIC–PCR profile allowed the typing of the 79 isolates into 68 ERIC-types and grouped the isolates into four main clusters (A–D), with the omphalitis isolates being grouped with the commensals and separated from the septicaemia and swollen head syndrome. These results indicate that ERIC–PCR is a technique that could replace other molecular characterization techniques such as random amplification of polymorphic DNA (RAPD)–PCR and restriction fragment length polymorphism (RFLP), reinforce previous observations that omphalitis isolates are just opportunistic agents, and are consistent with many reports that specific genotypes are responsible for causing specific diseases. Most of the isolates were either nontypable or rough, supporting the need for alternative methods for typing these isolates.