Purpose: The purpose of this study was to evaluate three methods for detection of biofilm formation in staphylococci. Methods: For detection of biofilm formation, 152 clinical isolates of Staphylococcus spp. were screened by tissue culture plate (TCP), Tube method (TM) and Congo red agar (CRA) method. Results: Of the 152 Staphylococcus spp. 88(57.8%) displayed a biofilm-positive phenotype under the optimized conditions in the TCP method and strains were further classified as high 22 (14.47 %) and moderate 60 (39.4 %) while in 70 (46.0 %) isolates weak or no biofilm was detected. Though TM correlated well with the TCP test for 18 (11.8 %) strongly biofilm producing strains, weak producers were difficult to discriminate from biofilm negative isolates. Screening on CRA does not correlate well with either of the two methods for detecting biofilm formation in staphylococci. Conclusion: The TCP method was found to be most sensitive, accurate and reproducible screening method for detection of biofilm formation by staphylococci and has the advantage of being a quantitative model to study the adherence of staphylococci on biomedical devices. Key words: Staphylococci, adherence, biofilm, tissue culture plate, Congo red agarStaphylococci are most often associated with chronic difficult to eradicate and are often resistant to systemic infections of implanted medical devices.1-3 The use of antibiotic therapy and removal of infected device becomes indwelling medical devices is important in the treatment of necessary.9-11 The differentiation of staphylococci with respect critically and chronically ill patients, however bacterial to its biofilm phenotype might help to elucidate the impact colonization of implanted foreign material can cause major of staphylococci in diagnosis of infections related to medical and economic sequel. The increased use of indwelling biomedical devices and these observations may have utility medical devices has had considerable impact on the role of in the prevention of device related infections. 12 staphylococci in clinical medicine. The predominant species isolated in these infections are Staphylococcus epidermidis A number of tests are available to detect slime production and Staphylococcus aureus,their major pathogenic factor being by staphylococci; methods include tissue culture plate (TCP), ability to form biofilm on polymeric surfaces. 4 Biofilm 13 tube method (TM), 14 Congo red agar (CRA), 15,17 consists of multilayered cell clusters embedded in a matrix bioluminescent assay 18 and light or fluorescence microscopic of extracellular polysaccharide (slime), which facilitates the examination. 19,20 These methods are often subject to severe adherence of these microorganisms to biomedical surfaces and analytical limitations and are unable to detect bacterial protect them from host immune system and antimicrobial adherence accurately. In this study, we simultaneously therapy.5 screened 152 clinical isolates of Staphylococcus spp. by TCP (standard and modified), TM and CRA methods for Biofil...

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The present study tracks the development of low-level azole resistance in in vitro fluconazole-adapted strains of Candida albicans, which were obtained by serially passaging a fluconazole-susceptible dose-dependent strain, YO1-16 (fluconazole MIC, 16 g ml ؊1 ) in increasing concentrations of fluconazole, resulting in strains YO1-32 (fluconazole MIC, 32 g ml ؊1 ) and YO1-64 (MIC, 64 g ml ؊1 ). We show that acquired resistance to fluconazole in this series of isolates is not a random process but is a gradually evolved complex phenomenon that involves multiple changes, which included the overexpression of ABC transporter genes, e.g., CDR1 and CDR2, and the azole target enzyme, ERG11. The sequential rise in fluconazole MICs in these isolates was also accompanied by cross-resistance to other azoles and terbinafine. Interestingly, fluorescent polarization measurements performed by using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene revealed that there was a gradual increase in membrane fluidity of adapted strains. The increase in fluidity was reflected by observed change in membrane order, which was considerably decreased (decrease in fluorescence polarization values, P value) in the adapted strain (P value of 0.1 in YO1-64, compared to 0.19 in the YO1-16 strain). The phospholipid composition of the adapted strain was not significantly altered; however, ergosterol content was reduced in YO1-64 from that in the YO1-16 strain. The asymmetrical distribution of phosphatidylethanolamine (PE) between two monolayers of plasma membrane was also changed, with PE becoming more exposed to the outer monolayer in the YO1-64 strain. The results of the present study suggest for the first time that changes in the status of membrane lipid phase and asymmetry could contribute to azole resistance in C. albicans.

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For 260 pneumococcal and 266 staphylococcal strains, ranbezolid MICs ranged from <0.06 to 4 g/ml. The MICs for pneumococci were similar irrespective of the strains' ␤-lactam, macrolide, or quinolone susceptibilities, and ranbezolid MICs for coagulase-negative staphylococci were lower than those for Staphylococcus aureus. Ranbezolid was bacteriostatic against pneumococci. Ranbezolid MICs were similar to or lower than those of linezolid. Vancomycin and quinupristin-dalfopristin were also very active.The incidence of pneumococci being resistant to penicillin G and other ␤-lactams and non-␤-lactams has increased worldwide at an alarming rate, including in the United States (1, 5, 9). There is an urgent need for oral compounds for outpatient treatment of respiratory tract infections caused by resistant pneumococci (1,5,8). The emergence of methicillin-and quinolone-intermediate, and recently glycopeptide-intermediate, staphylococci, as well as the propensity of these organisms to cause serious systemic infections in immunocompromised hosts, also necessitates other therapeutic modalities (7,12,21).The MICs of linezolid, an oxazolidinone which has been available clinically for the past few years, for pneumococci and staphylococci range between 0.5 and 4 g/ml, irrespective of the organisms' resistance to other agents (2-4, 6, 10, 15, 18). Ranbezolid (RBX 7644; Ranbaxy Research Laboratories, New Delhi, India) is a new parenteral oxazolidinone with enhanced activity against gram-positive aerobes and gram-positive and gram-negative anaerobes.The present study compared (i) the antipneumococcal activity of ranbezolid with those of linezolid, vancomycin, teicoplanin, quinupristin-dalfopristin, amoxicillin-clavulanate, ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, and erythromycin by using MIC and time-kill studies and (ii) the antistaphylococcal activity of ranbezolid with those of linezolid, vancomycin, teicoplanin, and quinupristin-dalfopristin by using an MIC study.The pneumococci tested comprised 89 penicillin-susceptible, 89 penicillin-intermediate, and 82 penicillin-resistant strains. Of these, 107 were erythromycin resistant. Twenty-six strains were quinolone resistant (levofloxacin MICs of Ն8 g/ml). For time-kill studies, 12 penicillin-susceptible, -intermediate, and -resistant strains (four of each), including six macrolide-resistant and two quinolone-resistant strains, were tested. Sixtyeight methicillin-resistant and 65 methicillin-susceptible Staphylococcus aureus strains and 69 methicillin-resistant and 64 methicillin-susceptible coagulase-negative staphylococci were examined.Ranbezolid susceptibility powder was obtained from Ranbaxy Research Laboratories. Other antimicrobials were obtained from their respective manufacturers. For testing with pneumococci, agar dilution was performed by using MuellerHinton agar (BBL Microbiology Systems, Cockeysville, Md.) supplemented with 5% sheep blood (11). Methicillin MIC plates for staphylococci were incubated for a full 24 h (11).For time-kill studies, tubes con...

Decreased susceptibility of Neisseria meningitidis isolates to ciprofloxacin emerged from an outbreak in Delhi, India. Results of antimicrobial susceptibility testing of the meningococcal isolates to ciprofloxacin and further sequencing of DNA gyrase A quinolone-resistance–determining region confirmed the emergence of ciprofloxacin resistance in the outbreak.

The observed MIC data warrant continued surveillance of susceptibility values of clinical cryptococcal isolates in India.

Oxazolidinones are known to inhibit protein biosynthesis and act against a wide spectrum of gram-positive bacteria. A new investigational oxazolidinone, ranbezolid, inhibited bacterial protein synthesis in Staphylococcus aureus and Staphylococcus epidermidis. In S. epidermidis, ranbezolid showed inhibition of cell wall and lipid synthesis and a dose-dependent effect on membrane integrity. A kill-kinetics study showed that ranbezolid was bactericidal against S. epidermidis. In vitro translation of the luciferase gene done using bacterial and mammalian ribosomes indicated that ranbezolid specifically inhibited the bacterial ribosome. Molecular modeling studies revealed that both linezolid and ranbezolid fit in similar manners the active site of ribosomes, with total scores, i.e., theoretical binding affinities after consensus, of 5.2 and 6.9, respectively. The nitrofuran ring in ranbezolid is extended toward C2507, G2583, and U2584, and the nitro group forms a hydrogen bond from the base of G2583. The interaction of ranbezolid with the bacterial ribosomes clearly helps to elucidate its potent activity against the target pathogen.