Novel hydroxamates potentiated in vitro activity of fluconazole against Candida albicans.

A set of 12 novel hydroxamate compounds (NHCs), structurally designed as inhibitors of histone deacetylase (HDAC) enzyme, were synthesized at our facility. These were adamantane derivatives with N-hydroxyacetamide as pharmacophore, and each of these compounds was tested for potentiating activity on fluconazole. The concentration of fluconazole which completely inhibited (concentration of complete inhibition [CCI]) the growth of Candida albicans ATCC 90028 and C. albicans ATCC 64550 was determined by micro-dilution method in the absence and presence of NHCs. The CCI of fluconazole without the NHC combination was 64 µg/ml and 1024 µg/ml against C. albicans ATCC 90028 and C. albicans ATCC 64550, respectively. The majority of the NHCs potentiated the fluconazole activity markedly as CCI of fluconazole against C. albicans ATCC 90028 reduced to 0.25 µg/ml. Similarly, CCI of fluconazole against C. albicans ATCC 64550 reduced to 4-8 µg/ml in combination with majority of NHCs while the best activity was displayed by the compound 1 with a reduction of CCI to 0.5 µg/ml. The study results revealed the potential usage of hydroxamate derivatives, structurally designed as HDAC inhibitors to enhance the activity of fluconazole against C. albicans.

Antibiotic susceptibility pattern of Enterobacteriaceae and non-fermenter Gram-negative clinical isolates of microbial resource orchid.

BACKGROUND: Microbial resource orchid is a collection of Gram-positive and Gram-negative clinical isolates sourced from different hospitals and diagnostic laboratories in India. We determined the antibiotic susceptibility of a set of Gram-negative Enterobacteriaceae and non-fermenter clinical isolates from microbial resource orchid, collected during the period of 2002-2012 against commonly used antibiotics. MATERIALS AND METHODS: A total of 247 Gram negative strains consisting of 142 Enterobacteriaceae and 105 non-fermenters from microbial resource orchid were selected for determining minimum inhibitory concentration against ß-lactams, aminoglycosides, quinolone, and tetracycline by agar dilution method as per clinical and laboratory standards institute guidelines. RESULTS: All the isolates had high resistance to ampicillin, piperacillin, ceftazidime, gentamicin, tetracycline, and ciprofloxacin. Pseudomonas aeruginosa showed moderate resistance to carbapenems. CONCLUSION: This study demonstrated the high level of antibiotic resistance among the strains collected under microbial resource orchid and further, such data and the strains can be used in new chemical entities profiling.

In vitro antibacterial activities of a novel oxazolidinone, OCID0050.

OBJECTIVES: In the pursuit of developing a second-generation oxazolidinone, we have identified OCID0050 as a novel oxazolidinone with enhanced activity against bacterial strains resistant to methicillin, vancomycin and linezolid. METHODS: MIC and MBC determinations were performed according to CLSI guidelines. Linezolid-resistant bacterial strains were generated in-house; inoculum effect, pH effect and kill kinetics experiments were performed as per standard protocols. RESULTS AND CONCLUSIONS: OCID0050 demonstrated better inhibitory potency against many of the tested clinically significant strains by generally showing 2-4-fold lower MICs than linezolid. In addition, it has higher inhibitory activity against linezolid-resistant strains.