| 2018 | Nanoplasmonics for Real-Time and Label-Free Monitoring of Microbial Biofilm Formation. | ACS Sens | Microbial biofilms possess intrinsic resistance against conventional antibiotics and cleaning procedures; thus, a better understanding of their complex biological structures is crucial in both medical and industrial applications. Existing laboratory methodologies have focused on macroscopic and mostly indirect characterization of mechanical and microbiological properties of biofilms adhered on a given substrate. However, the kinetics underlying the biofilm formation is not well understood, while such information is critical to understanding how drugs and chemicals influence the biofilm formation. Herein, we report the use of localized surface plasmon resonance (LSPR) for real-time, label-free monitoring of E. coli biofilm assembly on a nanoplasmonic substrate consisting of gold mushroom-like structures. Our LSPR sensor is able to capture the signatures of biofilm formation in real-time by measuring the wavelength shift in the LSPR resonance peak with high temporal resolution. We employ this sensor feature to elucidate how biofilm formation is affected by different drugs, including conventional antibiotics (kanamycin and Ampicillin) as well as rifapentine, a molecule preventing cell adhesion yet barely affecting bacterial viability and vitality. Due to its flexibility and simplicity, our LSPR based platform can be used on a wide variety of clinically relevant bacteria, thus representing a valuable tool in biofilm characterization and drug screening. |
| 1991 | Effect of various antibiotics on Listeria monocytogenes multiplying in L 929 cells. | Infection | Various antibiotics were evaluated as to their effect on Listeria monocytogenes SLCC 4013 multiplying within L 929 mouse fibroblast cells. Antibiotics were employed in concentrations above the MIC value. However, there was no measurable effect of some drugs on intracellular listeriae (azlocillin, mezlocillin, cephalothin, ciprofloxacin, chloramphenicol). With other drugs an inhibition of intracellular growth was observed (penicillin, Ampicillin, rifampicin, rifapentine, erythromycin, doxycycline, co-trimoxazole, coumermycin). Notably, with none of the antibiotics a complete eradication of the listeriae was achieved. There is a good correlation of these results with animal experiments. Therefore, the cell culture system might be useful for the screening of new antibiotics. |
| 1987 | Comparative in vitro activity of CI934, a new fluoroquinolone, alone and in combination with coumermycin, against gram-positive bacteria. | Drugs Exp Clin Res | The in vitro activity of Cl934, a new quinolone antimicrobial agent, was studied against 314 strains of Gram-positive bacteria representing 6 genera: Staphylococcus aureus, Streptococcus faecalis, S. agalactiae, S. pyogenes, S. pneumoniae, S. milleri, viridans streptococci, Listeria monocytogenes, Corynebacterium JK, Mycobacterium fortuitum and Bacillus spp.; and compared with that of enoxacin, ciprofloxacin, penicillin G, Ampicillin, coumermycin, oxacillin, vancomycin, teicoplanin, rifampin, rifapentine, LM 427, erythromycin, minocycline, tetracycline and clindamycin. The agar dilution method was used. Cl934 was very active in vitro, with MIC90 less than or equal to 0.5 mg/l against most species tested, except for S. faecalis and M. fortuitum. It was usually 2 to 8-fold more active than ciprofloxacin. Cl934 was also tested by the killing curve method, alone and in combination with coumermycin. It was rapidly bactericidal against most species tested, including S. faecalis. A synergistic interaction was observed with coumermycin against S. aureus, S. agalactiae, S. milleri and S. faecalis. The only antagonistic interaction occurred against L. monocytogenes exposed to 8 X MIC of Cl934 with 2 X MIC of coumermycin. |
| 1984 | Rifampicin and rifapentine in treatment of experimental listeriosis in normal mice and athymic (nude) mice. | Chemotherapy | Rifampicin and rifapentine were used in the treatment of Listeria monocytogenes infections in normal mice and congenitally athymic (nude) mice. Results were compared with untreated controls and with the results obtained from a previous study of Ampicillin in which this model was used. Low doses of rifampicin or rifapentine were adequate to cure normal mice. The efficacy of these antibiotic treatment schedules was lost in nude mice. Prolonged antibiotic treatment schedules with increased dosages were also unsuccessful. These studies show that rifampicin and rifapentine , two antimicrobial agents being capable of destroying intracellular bacteria, were not effective in curing the Listeria infection in mice with impaired host defenses. |