High incidence of hydrogen sulphide producing and citrate utilizing variants of Escherichia coli in meat

In the present investigation, the hydrogen sulphide producing and citrate utilizing variants of Escherichia coli was found in commercial beef and mutton samples. Out of the 106 beef and mutton samples, 55 E. coli was isolated and 20% of these organisms was found as hydrogen sulphide producer and 3.63% of them was found as both hydrogen sulphide producer and citrate utilizer. Serological examination revealed 11 different serotypes of E. coli. The reason for emerging high per cent of variants of E. coli in meat is not clear. However, acridine orange curing followed by isolation of plasmid and conjugal study showed that the production of hydrogen sulphide and capability of utilizing citrate are mediated by transferable plasmid. During the conjugal study, they were transferred with tetracycline and chloramphenicol resistance. Therefore, it may be considered that the genes mediating hydrogen sulphide production, citrate utilization and antibiotic resistance are positioned in R + plasmid. Transfer of the R + plasmid is the main cause for the emergence of hydrogen sulphide producing, citrate utilizing and antibiotic resistant E. coli. These coupled transfer of hydrogen sulphide producer as marker for emerging Multiple Antibiotic Resistance (MAR) organisms.