Abstract
Multidrug resistance (MDR) exhibited by some strains of Escherichia coli may be due to acquiring mobile genetic element (R-plasmid) by the bacteria, or intrinsically induced by inappropriate use of antibiotics by the hosts. Infection by such strains may result to prolonged illness and greater risk of death. The study evaluated the impact of curing on antibiotic resistance on selected clinical isolates of E. coli. Twenty clinical isolates of E. coli from our previous studies were re-characterized using conventional microbiological techniques. Antibiotic sensitivity testing was determined by disk diffusion method, MDR selected based on resistance to ≥ 2 classes of antibiotics. Multiple antibiotic resistance (MAR) index was determined as ratio of the number of antibiotic resisted to the total number of antibiotics tested and considered significant if ≥. 0.2. The isolates that showed significant MAR index were subjected to plasmid curing using acridine orange, thereafter, profiled for plasmid and the cured ones were re-tested against the antibiotics they initially resisted. Out of the 20 isolates, 19 (95%) were confirmed as E. coli, all (100%) of which were MDRs, which was highest against augmentin (78.9%) followed by amoxacillin (52.6%). However, after the plasmid curing only 6 (31.6%) out of the 19 isolates cured retained significant MAR index and the level of the significance had reduced drastically in 16 (84.2%) isolates. Conclusively, curing assay can completely eliminate R-plasmid acquired resistance. More studied on plasmid curing agents for possible augmentation of the agents into antibiotics may see the rise of successful antibiotic era again.
Highlights
There is an emergence of a new trend of antibacterial resistance against commonly used antibiotics (Giwa et al, 2019; Abdullahi et al, 2016)
From our findings, highest level of antibiotic efficacy was observed to stereptomycin, gentamicin and trimethoprim/sulfamethoxazole; perhaps, because both stereptomycin and gentamicin are administered by injection and trimethoprim sulfamethoxazole has not been commonly administered in treatment of infections cause by Gram negative bacteria
The role of the curing on reverting the antibiotic multidrug resistance depends on whether the resistance is acquired or induced (Duedu et al, 2017), The complete elimination of resistance against gentamycin and streptomycin by curing, suggests that the resistance is acquired, confirming further that the efficacy of antibiotics administered by injection is conserved (Sulaiman and Rufa’I, 2019; Guillermo et al, 2012), perhaps why the curing did not show a significant impact on resistance against the antibiotics administered orally as trimethoprim/sulfamethoxazole and amoxiciiln, as such the resistance observed against them may be due to inappropriate use of the antibiotics (DeSmet et al, 2011)
Summary
There is an emergence of a new trend of antibacterial resistance against commonly used antibiotics (Giwa et al, 2019; Abdullahi et al, 2016). Resistance plasmids (R plasmids) have been reported to be the most frequent cause of antibiotic resistance in most bacteria including the E. coli which have exhibited resistance to different antibiotics such as beta lactam antibiotics, aminoglycosides and fluoroquinolone (Carattoli, 2013; Zhang et al, 2014). They allow the movement of genetic materials including antimicrobial resistant genes between bacterial species and genera through gene exchange processes thereby causing a rapid spread of the antibiotic resistance (Carattoli, 2013; Daneman et al, 2013). The study aimed at determining the impact of curing on eliminating antibiotic resistance on selected clinical isolates of E. coli
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