The transmutation of Escherichia coli ATCC 25922 to small colony variants (SCVs) E. coli strain as a result of exposure to gentamicin

Background: Small colony variants (SCVs) are biotypes of bacteria that have a size of approximately one-tenth or less of the wild types and has distinct characteristics comparing to the wild type strains. Clinical SCVs are usually associated with persistent infection and require a long-term treatment program with antibiotics. In Saudi Arabia, there are few studies about SCVs Escherichia coli for this reason, this study is aimed to investigate the ability of gentamicin to mutate E. coli ATCC 25922 to produce small SCVs and investigate the genotypes and phenotypes changes and stress tolerance comparing to clinical SCVs E. coli and normal clinical E. coli Isolated from blood samples. Methods: In this investigation, four clinical blood samples were collected ted from patients and the cultivation and isolation were carried out in KFMC between December 2019 and February 2021. The identification of positive blood culture samples was done using phoenix MD. Non-SCV E. coli ATCC25922 were mutated to SCV using exposure to increasing gradual concentrations of gentamicin at 100-generation intervals. Biochemical features and susceptibility to standard antibiotics using automated Phoenix MD 50 and. The survival assays were done using several stresses including heat shock, low pH, high osmotic pressure, and oxidative pressure. Virulence genes screening included the detection of genes that encoded to α-haemolysin, CS12 fimbriae, F17-like fimbrial adhesion, P-related fimbriae, yersiniabactin siderophore system, P-fimbriae, aerobactin, iron-regulated genes using PCR and gel electrophoresis. Results: The data from the mutating E. coli ATCC 25922 small colony test with gentamicin revealed that the first emergence of the multidrug resistance (MDR) SCV E. coli strain occurred at generation number 250, corresponding to a gentamicin concentration of 57 g/ml. Pathogenicity islands detection revealed that all tested E. coli strains have PAI IV 536 genes on their chromosomes furthermore, mutated SCV E. coli ATCC 25922 acquired PAII CFT073 and PAI IV 536. Survival tests showed no significant differences changes in tolerance of mutated SCVs comparing to parental strain. Conclusion: The present work concluded that gentamicin sub-MIC concentration gradual exposure can induce mutation responsible for SCV formation and evolving of MDR E. coli strains. The mutated SCVs evolved high-level aminoglycoside resistance for gentamicin and resistance to amikacin, it also developed resistance to 2 cephalosporin antibiotics cefuroxime, and cephalothin and a resistance to aztreonam

Distribution of Candida infections in patients and evaluation of the synergic interactions of some drugs against emerging fluconazole- and caspofungin-resistant C. auris

Pathogenic multidrug-resistant Candida species are considered some of the most important health risks. This work aimed to evaluate and monitor the prevalence of the human pathogenic Candida strains isolated from patients in King Fahd Medical City (KFMD), Riyadh, Saudi Arabia, and to evaluate the synergy of some antimicrobial agents against Candida species’ resistance to antifungal drugs. The retrospective analysis, identification using biochemical tests, minimal inhibitory concentrations using E-tests, determination of the fraction inhibitory concentration index value for synergic testing, and simulation of 100 experiments using Monte Carlo simulation methods were performed according to standard protocols. The findings showed that all age groups of males and females can be infected by Candida species; furthermore, human pathogenic Candida species can be isolated from several clinical samples and different human body sites. The minimal inhibitory concentration results showed that many multidrug-resistant Candida strains, such as C. albicans, emerged in 2020 compared to 2018. Candida albicans remains the most important pathogen among all Candia species, found in 51.7 % and 42.4 % of the isolates in 2018 and 2020, respectively. In 2018, many isolates of C albicans showed resistance to itraconazole, fluconazole, anidulafungin, amphotericin B, ketoconazole, voriconazole, caspofungin, and flucytosine. In 2018, all C. auris isolates (N = 94) were resistant to fluconazole, and more than 85 % (N = 76) of C. albicans isolates were resistant to itraconazole, while only 5.9 % (N = 2) were resistant in 2018. The study concluded that the resistance to antifungal drugs among pathogenic yeasts is increasing and constantly changing and that surveillance of these pathogens must continue. Also, the synergy between drugs remains an appropriate option for confronting this risk, especially between natural extracts and drugs. Despite the lack of evidence for any antifungal and antibacterial drug's ability to synergistically suppress the fluconazole- and caspofungin-resistant C. auris strains diagnosed in this study, the surveillance and synergic tactics continue to be viable options for dealing with these human pathogenic yeasts