| dc.description.abstract | Centred on the current rate of antibiotics production and approvals, it is anticipated that by 2050 up to 10 million people could die annually due to multidrug-resistant (MDR) pathogens. One of the notable examples of antibiotic resistance is the evolution of carbapenem-resistant Enterobacteriaceae. The development of carbapenem-resistance (CR) is of great concern to the healthcare systems as there is no apparent next line of antibiotics to use against carbapenemase-producing (CP) Enterobacteriaceae. Among the Enterobacteriaceae, a high prevalence of carbapenem-resistance has been reported in Escherichia coli and Klebsiella pneumoniae. Indeed, the WHO expert committee on antimicrobial resistance included carbapenem-resistant Klebsiella pneumoniae and Escherichia coli associated with the severe urinary tract, bloodstream and lower respiratory tract infections as critical priority species. The ability to cause diseases is potentiated by the presence of virulence factors. The virulence factors influence the capacity of E. coli and K. pnuemoniae to infect and colonize different body systems. The coexistence of virulence and beta-lactamase encoding genes complicates treatment outcomes. To this effect, this study investigated the carbapenem resistance profiles of pathogenic E. coli and K. pnuemoniae in Uganda. Furthermore, nanomaterials and bacteriophages as alternative approaches to treat bacterial infections were evaluated.
A retrospective cross-sectional study was conducted using 421 E. coli and 227 K. pnuemoniae archived clinical isolates collected from four Uganda tertiary hospitals between January and December 2019. The isolates were subjected to antibiotics sensitivity assays to determine phenotypic resistance. Five sets of multiplex PCR were performed to detect Carbapenem-resistance genes; DEC pathotypes virulence genes; ExPEC PAI; E. coli phylogenetic groups; and K. pnuemoniae capsular pathotypes. Silver and copper oxide nanoparticles were green synthesized using plant extracts. Chitosan was isolated from the banana weevils, mushrooms and Nile perch scales by demineralization, deproteination and deacetylation. Chitosan nanoparticles were prepared using the ionic gelation method. The AgNPs, CuONPs, Chitosan, and its derivatives were characterized by UV Vis spectroscopy, XRD, FTIR, DLS, SEM, EDX and TEM. Assessment of the antimicrobial activity of AgNPs, CuONPs and chitosan was done by the agar well diffusion method. Furthermore, E. coli phages were isolated from sewage by the enrichment method. The phage host range was determined by the spotting assay. Synergism of phages and nanomaterials in the elimination of biofilms was performed on a 24 well plate. Morphological and molecular characterization of phages were conducted.
E. coli and K. pnuemoniae registered statistically similar phenotypic resistance (p-value = 0.9999). Molecular screening detected carbapenem-resistance determinants in 36.6% of the MDR isolates. K. pnuemoniae isolates recorded a genotypic prevalence of 43.2%, whereas E. coli scored 33.0%. Therefore, the prevalence of the carbapenem resistance genes was significantly higher in K. pnuemoniae (p-value < 0.0001). A significant variation between phenotypic and genotypic resistance was observed; however, the presence of resistance genes highly correlated with phenotypic resistance. A high-level carbapenem-resistance carriage was observed among pathogenic E. coli and K. pnuemoniae isolates. Among the 249 pathogenic E. coli, phenotypic resistance was found in 31.7% (79) isolates. For K. pnuemoniae capsular types, 34.9% (37/106) exhibited phenotypic resistance. Accordingly, compared to E. coli pathotypes, virulence factors and carbapenem resistance co-occurrence was significantly higher in K. pnuemoniae capsular types (p-value < 0.0049). Thus, the present study reinforces that carbapenem resistance is still a significant threat in Uganda as the phenotypic and genotypic resistance observed are statistically similar to those reported by earlier studies.
Two novel phages (named UGKSEcP1 and UGKSEcP2) without any undesirable genes belonging to the Myoviridae phage family, Tequatrovirus genus, exhibited lytic activity against all the detected carbapenem-resistant E. coli pathotypes and four uncharacterized carbapenem-resistant K. pnuemoniae clinical isolates with extensive clear plaques. Furthermore, chitosan isolated from locally available materials exhibited antibacterial activity at extremely high concentrations (>3000 µg/ml), whereas the biosynthesized silver and copper nanoparticles had potent antibacterial activity at low MICs. Silver nanoparticles and silver-chitosan nanohybrid significantly reduced the phage viability but did not completely inactivate. A combination of phages and nanomaterials significantly reduced the planktonic and biofilm bacterial population density than the individual components. Furthermore, we found that the cocktail of phages and nanomaterials was more effective in preventing biofilm formation than treating. As the combinatory effect of phages and the nanomaterials was significantly higher than the individual components against carbapenem-resistant E. coli planktons and biofilms, therapeutic formulations containing phages and nanoparticles should be considered as alternatives to combat antimicrobial resistance. | en_US |
