Pyelonephritis caused by multiple clones of Escherichia coli, susceptible and resistant to co-amoxiclav, after a 45 day course of co-amoxiclav

Objectives: We studied the clonal relatedness, in terms of phylogenetic group, virulence factors and co-amoxiclav resistance, of different Escherichia coli isolates obtained from blood and urine of a patient who had taken a 45 day course of co-amoxiclav. Patients and methods: The isolates were typed by molecular methods, and the virulence and resistance genes studied by PCR. Results: The four phenotypically different E. coli isolates were classified into four clones and two phylogenetic groups (B2 and A), and displayed different virulence gene patterns. The two isolates resistant to co-amoxiclav were phylogenetically and clonally different, and harboured two different bla(TEM) genes. Conclusion: These two bla(TEM) genes did not derive from each other following a mutant selection process in vivo.