Biofilm formation in Gardnerella vaginalis

Gardnerella vaginalis is the causative agent of bacterial vaginosis, the most common vaginal infection. Biofilm formation by G. vaginalis is necessary for the pathogenesis of the infection. MADELINE and colleagues conducted an evolve and re-sequence experiment in the laboratory, selecting for biofilm formation by G. vaginalis by serial passaging. They observed increased biofilm formation and increased cell aggregation. Short-read sequencing of populations at intervals throughout the experiment was conducted in order to measure changes in allele frequency. MADELINE observed convergent adaptation at a number of loci which may be important for biofilm formation in Gardnerella.

Antibiotic resistance in C. difficile

Clostridiodes difficile causes severe enteric infection. There has been emergent spread of a new clone that is resistant to metronidazole antibiotics. MADELINE conducted a genome-wide association study to determine the genetic basis of metronidazole resistance and found that a SNP in the promotor of nimB was strongly associated with resistance. Interestingly, the presence of this SNP strongly correlated with the presence of another SNP in gyrA, previously shown to confer fluroquinolone resistance.