Unusual clinical presentation of Mycobacterium fortuitum infection in an immunocompetent woman.

The Mycobacterium fortuitum group of rapidly growing nontuberculous mycobacteria is an uncommon cause of renal infection, particularly in otherwise healthy hosts. We describe a case of nephritis due to M. fortuitum in an immunocompetent woman with a clinical and radiological diagnosis of renal tuberculosis.

In vitro activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole compared with those of amphotericin B and fluconazole against clinical isolates of Candida spp. and fluconazole-resistant Candida albicans.

OBJECTIVES: The aim of this study was to investigate the in vitro antifungal activity of an isothiosemicarbazone cyclic analogue against isolates of Candida spp. including fluconazole-resistant Candida albicans. METHODS: We investigated the activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole (EM-01D2) against 114 clinical isolates of Candida spp., representing five different species, by microdilution, according to the NCCLS method 27-A. The activity against C. albicans biofilms was also investigated. Toxicity in vitro was evaluated by MTT reduction assay. RESULTS: EM-01D2 demonstrated low toxicity, broad spectrum, fungicidal activity and was active against C. albicans and Candida krusei at concentrations lower than those shown by amphotericin B and fluconazole (P < 0.05). It maintained potent in vitro activity against fluconazole-resistant C. albicans isolates. Fungicidal activity occurred at concentrations 1-2 doubling dilutions greater than the corresponding MICs, and time-kill analysis indicated that a 99.9% loss of C. albicans viability occurred after 6 h of incubation in the presence of EM-01D2 at concentrations equal to four times the MIC. EM-01D2 was also active in inhibiting the growth of C. albicans ATCC 10231 biofilms, even though such inhibition occurred at concentrations higher than the MICs determined under planktonic growth conditions. However, when C. albicans biofilms were pre-exposed to subinhibitory concentrations of EM-01D2, a reduction of MIC50 of amphotericin B was observed. CONCLUSIONS: Based on these results, EM-01D2 could represent a template for the development of novel fungicidal agents.

The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay as rapid colorimetric method for determination of antibiotic susceptibility of clinical Mycobacterium tuberculosis isolates in liquid medium.

We investigated the usefulness of a colorimetric method based on the reduction of a tetrazolium salt (XTT) for the susceptibility testing of clinical isolates of Mycobacterium tuberculosis to isoniazid, rifampin, rifabutin, ethambutol hydrochloride, ethionamide and streptomycin. The isolates and the ATCC reference strains reported as susceptible according to the agar dilution method approved by the National Committee for Clinical Laboratory Standards were found to be susceptible by the XTT colorimetric assay after times of incubation ranging between three days for rifampin and rifabutin to eight days for isoniazid. In comparison with other colorimetric methods reviewed in this article, the proposed assay is suitable for determining the susceptibility or resistance to most antituberculous drugs and, as a consequence of the water-solubility of the formazan yielded by reduction of XTT, additional steps such as the addition of extraction buffer and further incubation before the spectrophotometric analysis are not needed. The XTT reduction assay is an inexpensive, rapid and reliable screening method for the detection of susceptible, resistant and multidrug-resistant strains of M. tuberculosis and is an alternative to the costly performance of molecular or radiometric methods.

Comparison of the susceptibility testing of clinical isolates of Mycobacterium tuberculosis by the XTT colorimetric method and the NCCLS standards method.

The susceptibility or resistance of clinical isolates of Mycobacterium tuberculosis were determined by a method incorporating the 2,3-bis(2-methoxy-4-nitro-5-sulphophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and compared with results obtained by the National Committee for Clinical Laboratory Standards approved standard method (M24-T2). One hundred percent of all isolates demonstrated agreement between the susceptibility and resistance to isoniazid, rifampicin, and ethambutol obtained by the two methods, suggesting that the XTT-based method could provide a useful means for the rapid determination of antimycobacterial susceptibility of clinical isolates of M. tuberculosis.

Activity of a new class of isonicotinoylhydrazones used alone and in combination with isoniazid, rifampicin, ethambutol, para-aminosalicylic acid and clofazimine against Mycobacterium tuberculosis.

The activities of six derivatives of a new class of isonicotinoylhydrazones were investigated in vitro against Mycobacterium tuberculosis H37Rv ATCC 27294, isoniazid-resistant M. tuberculosis ATCC 35822, rifampicin-resistant ATCC 35838, pyrazinamide-resistant ATCC 35828, streptomycin-resistant ATCC 35820 and 16 clinical isolates of M. tuberculosis. Several compounds showed interesting antimycobacterial activity against both ATCC strains and clinical isolates, but were less active against isoniazid-resistant M. tuberculosis. Combinations of five isonicotinoylhydrazone derivatives and rifampicin, ethambutol, para-aminosalicylic acid, isoniazid and clofazimine were also investigated against M. tuberculosis H37Rv ATCC 27294 and against ATCC drug-resistant strains. Addition of sub-MICs of some isonicotinoylhydrazone derivatives resulted in a four- to 16-fold reduction in MICs of ethambutol, para-aminosalicylic acid and rifampicin with fractional inhibitory concentrations (FICs) ranging between 0.17 and 0.37, suggesting a synergic interaction against M. tuberculosis H37Rv. Increased activity was also observed with other combinations (FICs 0.53-0.75), including isoniazid, and a synergic interaction between one of the isonicotinoylhydrazone derivatives and isoniazid (FIC 0.26) was shown against isoniazid-resistant M. tuberculosis ATCC 35822, whereas no effects were observed on combining the isonicotinoylhydrazones with clofazimine. The ability of isonicotinoylhydrazones to inhibit specifically the growth of M. tuberculosis, the high selectivity index and their ability to enhance the activity of standard antituberculous drugs in vitro indicate that they may serve as promising lead compounds for future drug development for the treatment of M. tuberculosis infections.