Septicemia caused by cysteine-dependent Escherichia coli

First report of brain abscess caused by a satelliting phenotypic variant of Helcococcus kunzii

Helcococcus kunzii was isolated from a brain abscess in a diabetic patient with cholesteatoma and demonstrated satellitism around Staphylococcus aureus in culture. This is the first reported case of severe central nervous system infection due to H. kunzii and the first description of a satelliting phenotypic variant of this organism.

Highly resistant metabolically deficient dwarf mutant of Escherichia coli is the cause of a chronic urinary tract infection

We present the case of a 68-year-old diabetic woman who has been suffering from chronic urinary tract infections, recurring over a period of at least 5 years, caused by a slowly growing metabolically deficient dwarf mutant (MDD) of Escherichia coli. This MDD strain was auxotrophic for histidine, was resistant to multiple antibiotics, and showed atypical growth behavior. Colonies were tiny on routine media but were able to revert to normal growth after extended incubation. This strain was identified as E. coli by 16S ribosomal DNA sequencing, and virulence factor profiles were determined by PCR. Seven MDD isolates collected over the 5-year period were grown from midstream urine to significant colony counts and shown to belong to the same clonal group by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus PCR. These MDDs were repeatedly misidentified by biochemical methods due to their slow growth and atypical colony morphology. This case highlights the importance of recognizing MDDs of Enterobacteriaceae in patients with chronic infections. To our knowledge this is the first report of an MDD of E. coli causing a chronic urinary tract infection.