In Vitro Susceptibility of Pythium insidiosum to Macrolides and Tetracycline Antibiotics

Abstract

We describe the in vitro activity of macrolides and tetracycline antibiotics against Pythium insidiosum. The MICs were determined according to CLSI procedures (visual MIC) and by a colorimetric method [3-(4,5-dimethyl-2-thiazyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT)]. The lowest geometric mean (GM) MIC (MICs in g/ml) (0.39 and 0.7 by visual reading and colorimetric method, respectively) and MIC ranges (0.125 to 2.0) were obtained for minocycline, while the highest MICs were shown for erythromycin (GM of 7.58 and 12.25 by visual reading and colorimetric method, respectively, and MIC ranged from 2 to 32). This significant in vitro activity makes these classes of antibiotics good candidates for experimental treatment of pythiosis.

In Vitro Synergism between Azithromycin or Terbinafine and Topical Antimicrobial Agents against Pythium insidiosum

“…Previous studies demonstrated the in vitro and in vivo susceptibility of P. insidiosum to azithromycin, mupirocin, and terbinafine (8,(13)(14)(15)(16)(17)(18)(19) with in vitro results similar to those of our study. Although all other evaluated antimicrobials have a wide range of known antimicrobial activities against bacteria, some fungi, and parasites (20,21), this study was the first to evaluate the antimicrobial activities of benzalkonium, cetrimide, cetylpyridinium, potassium permanganate, and triclosan against clinically isolated P. insidiosum based on broth microdilution susceptibility tests.…”

Pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Parte 1. Caracterización clínica

“…State-of-the-art antimycotics such as carposfungin (an inhibitor of β-glucan synthesis) showed a reduction in lesions, but when the treatment was stopped the growth of the lesions restarted (21); combinations of itraconazole and terbinafine or voriconazole and terbinafine showed some degree of success in comparison with isolates of P. insidiosum (22,24). Likewise, Loreto et al (26) reported the in vitro susceptibility of P. insidiosum to macrolide antibiotics and tetracyclines by reducing the incorporation of amino acids into proteins.…”

“…These molecules include proinflammatory cytokines, such as IL-1, IL-6 and alpha tumor necrosis factor (TNF-α), clonal expansion and IL-2, subset of auxiliary T lymphocytes (Th1), IL-12 and gamma interferon (IFN-γ) and, to a lesser extent, the Th2, IL-4 and IL-5 subset, colony-stimulating factors such as granulocyte and macrophage (GM-CSF), chemokines such as RANTES and MIP-1α, adhesion molecules such as ICAM1, ELAM-1 and E-selectin, inflammatory mediators such as bradykinin, histamine, eicosanoids and nitric oxide, as well as molecules involved in the presentation of antigen and class II major histocompatibility complex (MHC). The entire spectrum of molecular albs explains pleiotropy and the anti-inflammatory and immunomodulatory Loréto et al (26), reportaron susceptibilidad in vitro de P. insidiosum a los antibióticos macrólidos y tetraciclinas por la reducción de la incorporación de aminoacidos a las proteínas.…”

Combat-Related Pythium aphanidermatum Invasive Wound Infection: Case Report and Discussion of Utility of Molecular Diagnostics

“…Several antibacterial agents and the squalene oxidase inhibitor terbinafine have been shown to have some in vitro synergistic activity, but these have been published only for P. insidiosum. In these studies, a wide range of synergistic effects was noted among the 17 isolates tested, suggesting that different strains may have different susceptibilities (4,9). In an in vivo rabbit model of P. insidiosum infection, a combination of terbinafine, itraconazole, and fluvastatin was associated with the smallest amount of hyphae relative to other combinations (8).…”