ß-lactam antibiotics & vancomycin increase the growth & virulence of Candida spp.

AIM: To investigate the direct effect of antibiotics on growth and virulence of the major Candida species associated with invasive infections. MATERIALS & METHODS: Cefepime, imipenem, meropenem, amoxicillin and vancomycin were tested at twofold the peak plasma concentration (2× PP) and the peak plasma concentration (PP). The effects of antibiotics on Candida albicans, Candida parapsilosis, Candida krusei and Candida tropicalis were investigated by colony counting, flow cytometry, proteolytic activity and virulence in Caenorhabditis elegans. RESULTS: Antibiotics increase growth and proteolytic activity of Candida spp; In addition, amoxicillin potentiates virulence of C. krusei and C. tropicalis against Caenorhabditis elegans. CONCLUSION: These results suggest that antimicrobial therapy may have a direct effect on the pathophysiology of invasive fungal infections in patients at risk.

Bipolaris hawaiiensis as an emerging cause of cutaneous phaeohyphomycosis in an Antillean manatee Trichechus manatus manatus.

Phaeohyphomycoses are emerging and opportunistic diseases caused by dematiaceous fungi that infect many animal species. This paper describes a case of cutaneous phaeohyphomycosis in an Antillean manatee Trichechus manatus manatus caused by Bipolaris hawaiiensis. Blackish skin lesions were observed in an Antillean manatee calf held captive in Brazil. Direct examination of skin scraping from the affected areas revealed the presence of dematious hyphae. Culture of skin fragments led to the isolation and subsequent identification of B. hawaiiensis as the etiologic agent. Treatment with itraconazole for 14 d was effective. Infections by Bipolaris spp. are rare in animals, and this is the first report of B. hawaiiensis in veterinary medicine.

Synthesis and antifungal activity in vitro of isoniazid derivatives against histoplasma capsulatum var. capsulatum.

Histoplasmosis is a severe infection that affects millions of patients worldwide and is endemic in the Americas. Amphotericin B (AMB) and itraconazole are highly effective for the treatment of severe and milder forms of the disease, but AMB is toxic, and the bioavailability of itraconazole is erratic. Therefore, it is important to investigate new classes of drugs for histoplasmosis treatment. In this study, a series of nine isoniazid hydrazone derivatives were synthesized and evaluated for their antifungal activities in vitro against the dimorphic fungus Histoplasma capsulatum var. capsulatum. The drugs were tested by microdilution in accordance with CLSI guidelines. The compound N'-(1-phenylethylidene)isonicotinohydrazide had the lowest MIC range of all the compounds for the yeast and filamentous forms of H. capsulatum. The in vitro synergy of this compound with AMB against the planktonic and biofilm forms of H. capsulatum cells was assessed by the checkerboard method. The effects of this hydrazone on cellular ergosterol content and membrane integrity were also investigated. The study showed that the compound alone is able to reduce the ergosterol content of planktonic cells and can alter the membrane permeability of the fungus. Furthermore, the compound alone or in combination with AMB showed inhibitory effects against mature biofilms of H. capsulatum. N'-(1-Phenylethylidene)isonicotinohydrazide alone or combined with AMB might be of interest in the management of histoplasmosis.

Antifungal susceptibility of emerging opportunistic yeasts and yeast-like fungi from Rhea americana.

Opportunistic yeasts and yeast-like fungi have been recognized as important pathogens in high-risk patients. This study aimed to evaluate the presence of these microorganisms in the microbiota of captive rheas and to investigate the antifungal susceptibility of the isolated strains. Isolates representing Magnusiomyces capitatus (Geotrichum capitatum, n = 11), Trichosporon mucoides (n = 11), Trichosporon asteroides (n = 5), Rhodotorula mucilaginosa (n = 4), Trichosporon asahii (n = 3), Trichosporon cutaneum (n = 3), and Trichosporon ovoides (n = 3) were obtained from the oropharynx, cloaca, and feces of 58 animals. Most of the isolates were susceptible to antifungals in vitro; however, resistance against fluconazole (n = 1) and itraconazole (n = 2) was detected among T. mucoides. This study indicates that healthy rheas can be reservoirs of opportunistic pathogens. Primary resistance to azoles in T. mucoides obtained from these animals demonstrates the potential risk to humans.