1. Department of Chemistry, University of Nairobi, P.O. Box 30197, 00100 Nairobi, Kenya
2. Department of Physical and Biological Sciences, Kabarak University, Private Bag-20157, Nakuru, Kenya
3. Department of Chemistry and Molecular Biology, University of Gothenburg, and Centre for Antibiotic Resistance Research (CARe) at the University of Gothenburg, SE-405 30 Gothenburg, Sweden
4. Department of Chemistry - Ångström, Uppsala University, SE-751 20 Uppsala, Sweden
5. Department of Chemistry - BMC, Uppsala University, SE-752 37 Uppsala, Sweden