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The high frequency of infectious diseases has spurred research into effective tactics to combat microorganisms that are resistant to several drugs. The overproduction of the transmembrane efflux pump protein NorA, which may export hydrophilic fluoroquinolones, is a common mechanism of resistance in S. aureus strains. This work evaluated the antimicrobial activity of the ethanolic extract from the leaves of Croton heliotropiifolius (EECH) against different bacterial and fungal strains, as well as investigating its modulating effect on the resistance to norfloxacin in a Staphylococcus aureus SA1199B overproducing the NorA efflux pump. Microdilution assays were used to assess the EECH’s antibacterial efficacy. The MIC of norfloxacin or ethidium bromide (EtBr) against the SA1199B strain was determined in the presence or absence of the EECH in order to assess the modifying influence on drug resistance. The EECH showed no activity against the Gram-positive and Gram-negative bacterial strains tested. The EECH also showed no antifungal activity against Candida albicans ATCC 10231. On the other hand, the extract reduced the MIC values for norfloxacin against SA1199B at subinhibitory concentrations. In addition, the EECH also reduced the MIC values of EtBr at subinhibitory concentrations, suggesting the occurrence of phytochemicals that inhibit efflux pumps. Molecular docking showed that retusin, a flavonoid found in the extract, could compete with norfloxacin at the orthosteric site of the NorA, indicating that it could be a potential efflux pump inhibitor. However, isolated retusin did not enhance the activity of norfloxacin or EtBr and it did not inhibit the EtBr efflux, showing that it is not a NorA inhibitor. Even though C. heliotropiifolius is a source of phytochemicals that function as adjuvants for norfloxacin, isolated retusin cannot be used in conjunction with norfloxacin to treat infections brought on by S. aureus that overproduces NorA. Full article

Fungi are one of the most important and diverse groups of organisms on the planet, having a dual impact on humanity. They adversely impact human and animal health and can be a scourge to agriculture, while in turn serving as a beneficial source for foods and beverages, new medications, and biocontrol. There are approximately 1.5 million different species of fungi on Earth, which largely reside in soil and plant. They are also readily found on human skin and within the gastrointestinal and genitourinary tract, yet only about 300 species are known to make people sick [1,2]. Fungi are bountiful in the environment and we encounter them everyday, usually in the form of freely dispersed spores and hyphal fragments that we breath-in. Typically, encounters with fungi are harmless, as the human immune systems is well poised to handle such interactions. However, some fungal species pose significant health risks, such as endemic mycoses or those producing toxins like mycotoxins. Most importantly, immune dysfunction can lead to serious life-threatening diseases or severe fungal-induced allergic diseases such as asthma or other chronic conditions [3]. In fact, most invasive fungal diseases are associated with changes in the host such as immunosuppression, antibiotic-mediated disruption of microflora, or other immunosuppressing conditions resulting from HIV/AIDS and hematologic malignancies [3,4]. Such diseases require therapy with antifungal agents. Yet, there are only limited classes available to treat invasive fungal infection, and emerging drug resistance further restricts treatment options. In some cases, agents used to control agriculturally important moulds are the same class as those used to treat humans, and de novo resistance can emerge from the environment [5]. Fungi are not always easy to detect and cryptic chronic infections in the form of unculturable organisms can confound diagnosis [6]. [...] Full article

A new series of salicylanilide acetates was synthesized and evaluated for their in vitro antifungal and antituberculotic activity. Some of the evaluated compounds possessed comparable or better antifungal activity than a fluconazole standard. All these compounds exhibited very good potential and their in vitro activity against drug resistant and sensitive clinical isolates of Mycobacteria were found to be equivalent or better than a standard of isoniazide, a well-known first-line drug for tuberculosis treatment. Full article