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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.

Background: The upgrowth and rapid prevalence of pandrug-resistant Acinetobacter baumannii strains that have a pathogenic activity to cause several infections are of considerable influence on the health of communities worldwide. No infections by these bacterial strains were recorded before 1998, and currently, the numbers are on the rise. Methods: The A. baumannii strains were isolated from male and female patients in Medical Microbiology Department, King Fahd Medical City (KFMC) in Riyadh, Saudi Arabia between 1/1/2020 to 29/12/2020. The statistical analysis was performed base on sex, age, source of samples, and response to commercially available antibiotics. The A. baumannii strains that resisted all the antibiotics including colistin and imipenem were selected for the synergic test. Results: The data showed that 62.28%, 77.07% of 342 A. baumannii strains were isolated from males and patients over 35 years of age. A. baumannii strains (pandrug-A. baumannii) that can resist all tested antibiotics were 8.19%. The major source of the A. baumannii isolates was the respiratory system (>50%). Among all isolates (N = 342), azidothymidine-resistant A. baumannii strains were more than 85%. There is a statistically significant difference (P < 0.05) in the number of colistin-resistant A. baumannii strains isolated from males comparing with the female. The combinations of colistin and silver nanoparticles or imipenem and silver nanoparticles resulted in synergistic action led to reduction of MICs of colistin, imipenem, and silver nanoparticles (more than four-fold reduction). Also, the combinations of colistin and imipenem had high synergistic action. Conclusion: The pandrug-resistant A. baumannii strains may represent a current and future threat that must be fought, and the synergy action of antibiotics and nanoparticles may be one of the available, rapid, and easy strategies to confront this global problem.