Antifungal susceptibility testing of Candida tropicalis biofilms against fluconazole using calorimetric indicator resazurin.

Background: C.tropicalis is an important cause of nosocomial infections particularly in immunocompromised patients. Infections caused by Candida spp. are often associated with biofilm formation on implanted medical devices or on epithelial cell surfaces. Phenotypic characteristics of sessile cells in biofilms are known to be different from those of their free-living, planktonic counterparts. Biofilm forming strains often show increased resistance to antimicrobial agents. Materials and Methods : We measured susceptibility to fluconazole of fifty C.tropicalis isolates from immunocompromised (29) and immunocompetent (21) patients by minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC) assays. MBIC was done using the calorimetric indicator resazurin, to measure the metabolically active cells. Results : Biofilm forming cells showed increased resistance to fluconazole. Conclusion : The resazurin dye test was found to be a good method for determining MBIC.

Infective endocarditis due to Acinetobacter baumannii complex--a case report.

We report a case of infective endocarditis caused by Acinetobacter baumannii complex in a 27-year-old male patient. The patient presented with fever of five days duration, palpitation, dyspnea, cough and chest pain. He had undergone a surgical repair of ruptured aneurysm of sinus of valsalva a month before. The transthoracic echocardiogram revealed a large vegetation on the aortic valve. Three samples of blood for culture grew gram-negative pleomorphic coccobacilli within 24 hours which were identified by cultural and biochemical characteristics to be Acinetobacter baumannii complex. Antimicrobial susceptibility was performed by Kirby-Bauer method and the isolate were found to be resistant to ampicillin, Ciprofloxacin, Ceftriaxone, Gentamicin, Amikacin, Augmentin, Levofloxacin, Piperacillin-Tazobactam, Netilimicin and sensitive to Imipenem. Patient was initially treated with Ceftraixone and Gentamicin and subsequently with Ampicillin and Amikacin but did not respond to treatment and died of sepsis before therapy with Imipenem could be started.