Date of Award


Degree Type


Degree Name

Master of Science (MS)


Microbiology and Immunology


As many as 1 in 2 women will have at least one urinary tract infection (UTI) in their lifetime. UTIs can cause complications in pregnancy and decrease quality of life, and their treatment and prevention are expensive. Uropathogenic E. coli (UPEC) is the primary cause of UTI. The probiotic and bactericidal capacities of gut and vaginal Lactobacillus isolates have been studied, but the same attention has not been paid to urinary strains. These urinary isolates of L. crispatus appear to have a greater killing capacity against UPEC and this bactericidal activity does not depend on the cells themselves, consistent with the hypothesis that they secrete a molecule with anti-UPEC activity. In the future, this bacterium could be useful as a probiotic and molecules it produces could be used as antibacterial compounds.

The SCS of one urinary isolate of L. crispatus killed several logs of UPEC within 2 hours of exposure. This isolate creates a more acidic environment than isolates of other Lactobacillus species, but the killing of UPEC was not due to low pH alone, as buffered of the SCS delayed but did not eliminate the bactericidal effect. This effect became stronger after the SCS was left to sit for 24 hours. The molecule was not heat sensitive.

A urinary L. crispatus isolate produces a unique soluble molecule that can kill up to 9 logs of UPEC within 24 hours. The molecule may be an antimicrobial peptide or bacteriocin. Further experiments are required.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Included in

Microbiology Commons