Methods to detect the occurrence of various indicator bacteria on the surface of retail poultry in Spain

Contamination levels (cfu/g and cfu/cm(2)) of indicator microorganisms in retail broiler chicken carcasses in Leon (Spain) were investigated. Counts (log(10) cfu/g) were 5.19, 3.04, 2.73, 3.38, and 3.16 for total aerobic counts (TAC), Enterobacteriaceae, coliforms determined by the standard VRBA method (coliforms-VRBA), coliforms determined by the Hydrophobic Grid Membrane Filter method (coliforms-HGMF), and Escherichia coli (HGMF method), respectively. These values fit into the microbiological criteria for poultry meat consulted. A low correlation coefficient was found between TAC and Enterobacteriaceae counts (r = 0.308; P = 0.053) and between coliforms-VRBA and coliforms-HGMF counts (r = 0.398; P = 0.048). The determination method had a significant influence on the coliform counts obtained. All broiler chicken carcasses harbored E coli biotype I. E. coli biotype 11 was detected in 20% of the samples. The HGMF method was not completely specific for detecting E. coli since 11.25% of false positive colonies were found.