Drug-resistant bacterial contamination and efficacy of selected herbal medicines sold in Kampala city, Uganda (MakIR) (Unpublished PhD Thesis) Makerere University Kampala Uganda

A thesis submitted to the Directorate Of Research And Graduate Training for the award of the degree of Doctor of Philosophy of Makerere University

Background: Antimicrobial resistance (AMR), is when pathogens such as bacteria evade activities of drugs to which they were once susceptible, causing treatment failure. The AMR is escalating and is among the leading causes of global mortality, projected at 10 million annual deaths by 2050. Transmission of resistant bacteria to humans may occur through the food chain, the environment, or direct interactions with animals and plants such as herbal medicines. Effective redress needs thwarting the evolution and spread of resistant bugs, and discovery of effective drug substitutes. With the proliferation of herbal medicines (HM) trade in Kampala city where this study was carried out, it is unclear whether these HM are drivers of resistant bugs, or are possible drug candidates to resolve AMR. The aim of this study was to examine the drug-resistance traits of bacteria isolated from HM, and antibacterial activities of some medicinal plants in Kampala, to inform and support the safe use of HM in counteracting AMR. Methods: The prevalence of bacterial strains in 140 HM was examined using conventional culture, following the guidelines of World Health Organization. Drug resistance traits were tested using Kirby Bauer disc diffusion methods and Polymerase Chain Reaction. Plants species frequently used in treating ailments potentially caused by bacteria were identified ethnopharmacologically and their in-vitro antibacterial potency was evaluated using agar-well diffusion method. The potential enablers of HM bacterial contamination were examined with semi-structured questionnaires, key Iinformant Iinterviews, and field observations. Data were analysed using D'Agostino-Pearson test, Chi-square, and Mann-Whitney U tests (P≤ 0.05), with STATA version-15.0. Graphs were plotted using GraphPad Prism® version 9.0.0. Results: Fifty-nine bacterial strains were isolated from 45 (32.1%) samples, that is, Klebsiella pneumoniae: n=34; 57.6%, Escherichia coli: 12; 20.3%, Staphylococcus aureus: 7; 11.9%, Klebsiella oxytoca: 3; 5.1%, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. (1; 1.7% each). Salmonella spp. and Shigella spp. were not encountered. The bacteria were mostly resistant to: Penicillins (n = 45; 76.2%), Fluroquinolones (32; 54.2%), Carbapenems (18; 10.2%), 3rd and 4th generation cephalosporins (18; 15.3%), and (8; 30.5%) respectively. Majority of the bacteria (43; 72.9%) resisted more than three antibiotics (multidrug resistant/MDR strains), and comprised mostly; K. pneumoniae (28 out of 34; 82.4%), E. coli (6 out of 12; 50%), and S. aureus (7 out of 12; 58.3%). Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus had average AMR indices above the critical value (0.2), indicating high risk to the community. The MDR genes: Extended spectrum β-lactamases and Carbapenemases were found in eight and five out of 20 isolates respectively, while AmpC, and MecA were not detected. Novel evidence was generated for the high potency of Citrus limon leaf extracts against MDR S. pneumoniae NCTC 12977, K. pneumoniae ATCC 700606, and clinical isolates of K. pneumoniae and S. pneumoniae. C. limon fruit juice was equally strong against S. pneumoniae. Momordica foetida leaves were weak, narrow spectrum antibacterial agents with bacteriostatic effects only on S. pneumoniae, while Conyza pyrrhopappa leaves had no activity. E. coli was resistant to all the plant extracts. Policy, environmental, and herbalist related factors were among the major potential barriers to HM microbial safety. Conclusion: Though this research highlighted quality and efficacy limitations, it has generated novel evidence supporting the possible usefulness of HM in developing powerful bio-therapeutics, to manage bacterial diseases which have become incurable with clinical drugs.

Islamic Development Bank