Please cite this software:
"Multilocus sequence typing by blast from de novo assemblies against PubMLST", Andrew J. Page, Ben Taylor, Jacqueline A. Keane, The Journal of Open Source Software, (2016). doi: http://dx.doi.org/10.21105/joss.00118
All of the data is downloaded from PubMLST, so please cite it:
"BIGSdb: Scalable analysis of bacterial genome variation at the population level", Jolley & Maiden 2010, BMC Bioinformatics 11:595. http://dx.doi.org/10.1186/1471-2105-11-595
Please also consider citing the individual MLST databases, since it takes a lot of time an effort to curate and maintain them. A full list is here: http://pubmlst.org/databases/