In vitro antimicrobial activity of the new antibiotic vermisporin

The antimicrobial activity of vermisporin, a new antibiotic produced by fermentation of the fungusOphiobolus vermisporis, was tested in vitro. Vermisporin inhibited 90 % ofBacteroides fragilis and otherBacteroides spp. at 1 µg/ml (range 0.25–1 µg/ml).Clostridium perfringens were inhibited by 1 µg/ml (range 0.25–2 µg/ml). Vermisporin inhibited 90 % ofStaphylococcus aureus, including methicillin-resistantStaphylococcus aureus, at 0.5 µg/ml (range 0.12–0.5 µg/ml). Vermisporin MICs for group A, B, C, F and G streptococci were < 1 µg/ml when tested in Haemophilus Test Medium but 8 µg/ml in the presence of blood. Vermisporin MICs forEnterobacteriaceae, Pseudomonas aeruginosa andHaemophilus influenzae exceeded 64 µg/ml. Inhibited organisms had MBCs 16- to 32-fold above the MICs.     

In vitro activity of aztreonam--a new monocyclic beta-lactam antibiotic

The in vitro antibacterial activity of aztreonam (SQ 26776), a new beta-lactam antibiotic, was measured by the agar dilution technique. Aztreonam is known to have a narrow spectrum with activity only against Gram negative bacteria. The strains tested were 223 clinical isolates from blood cultures obtained at Rigshospitalet, Copenhagen, Denmark. Its activity against E. coli, Klebsiella spp., Proteus spp., Enterobacter spp., Citrobacter, Salmonella typhimurium and Serratia marcescens was satisfactory with MIC values normally below 0.5 mg/l. However, six out of 135 strains of E. coli showed surprisingly high MIC values of eight and 16 mg/l. The activity against Pseudomonas spp. and Acinetobacter spp. were limited, but the majority were inhibited by concentrations of aztreonam between 2.0 and 8.0 mg/l. The MIC values for the tested anaeobic bacteria were high, ranging from 8.0 to above 512 mg/l. With its narrow spectrum of activity, aztreonam seems to be a valuable addition to the antibiotic arsenal. Clinical studies will determine its real value.     

In vitro evaluation of E-4695, a new fluoro-naphthyridine

Compound E-4695, a C-7 azetidinyl fluoro-naphthyridine, was compared to six structurally related quinolones and was generally two- to four-fold more active than ciprofloxacin. E-4695 was particularly active againstStaphylococcus aureus (MIC90 0.06 mg/l),Staphylococcus haemolyticus (MIC90 0.5 mg/l),Klebsiella spp. (MIC900.015 mg/l),Serratia marcescens (MIC90 0.06 mg/l),Acinetobacter spp. (MIC900.015 mg/l),Pseudomonas aeruginosa (MIC90 0.5 mg/l),Xanthomonas maltophilia (MIC90 0.5 mg/l), andNeisseria gonorrhoeae (MIC900.001 mg/l). This new quinolone-like drug requires further investigations to confirm these promising in vitro findings.     

In vitro antibacterial activity of clarithromycin, a new macrolide antibiotic, and regression curve

This study was set up to establish the regression curve for clarithromycin inhibition zone diameters (disks 15 micrograms) and MIC to create a strain distribution plot, in order to allow accurate interpretation of the disk diffusion method for testing susceptibility to clarithromycin. 430 bacterial strains were studied in three university hospital. Clarithromycin was active against erythromycin sensitive Staphylococcus aureus and coagulase negative Staphylococci at concentrations of 0.12 to 0.25 microgram/ml (mode 0.25). Erythromycin resistant strains were also resistant to clarithromycin. Enterococci could be divided into two populations, one resistant (MIC greater than 128 micrograms/ml) and the other with MIC of 0.06 to 2 (mode 0.25). This was also the case for Streptococci and Pneumococci with MIC lower for susceptible strains (mode 0.03 to 0.06). Clarithromycin was active on Haemophilus at concentrations of 4 to 64 micrograms/ml (mode 16); MICs for beta-lactamase producing strains were comparable to those of strains not producing. MICs for Neisseria were 0.12 to 16 and for B. catarrhalis 0.016 to 0.5. MIC were 0.5 and 1 (mode 1) for Clostridium perfringens; Bacteroides fragilis strains were inhibited by 0.12 to 8 micrograms/ml (mode 0.5-1). So, antibacterial activity of C was similar to that of E; it was sometimes slightly superior, particularly on Gram positive cocci. For MIC breakpoints of 1 and 4 micrograms/ml, zone size breakpoints should be 23 and 17 mm and for 2 and 8 micrograms/ml, 20 and 15 mm.     

In vitro evaluation of the clastogenicity of fumagillin

Fumagillin, an antibiotic compound produced by Aspergillus fumigatus, is effective against microsporidia and various Amoeba species, but is also toxic when administered systemically to mammals. Furthermore, a recent in vivo study by Stanimirovic Z et al. 2007: (Mutat Res 628:1-10) indicated genotoxic effects of fumagillin. The aim of the present study was to investigate and explain the clastogenic effects of fumagillin (in the form of fumagillin dicyclohexylamine salt) on human peripheral blood lymphocytes in vitro by sister-chromatid exchanges (SCE), chromosome aberrations (CA), and micronucleus (MN) tests. The mitotic index (MI), proliferation index (PI), and nuclear division index (NDI) were calculated to evaluate the cytotoxic potential of fumagillin. Five concentrations of fumagillin (0.34, 0.68, 1.02, 3.07, and 9.20 microg/ml) were applied to lymphocyte cultures. All the tested concentrations of fumagillin increased the frequency of SCE per cell significantly (P < 0.001 or P < 0.01) compared with the negative control. A significant (P < 0.001) increase in frequency of structural CA was observed at the three highest concentrations in comparison with the negative control. In addition, the three highest test concentrations increased MN formation and decreased MI, PI, and NDI significantly compared with the negative control. The present results indicate that fumagillin is clastogenic and cytotoxic to cultured human lymphocytes.     

In vitro evaluation of antibiotic release from and bacteria growth inhibition by antibiotic-loaded acrylic bone cement spacers

The antibiotic release from and the bacteria growth inhibition by antibiotic-loaded acrylic bone cement hip spacers were studied. The cement used was Palacos R, and it was loaded with either one antibiotic powder (gentamicin, vancomycin, teicoplanin, or synercid) [monoantibiotic case] or two antibiotic powders (gentamicin + vancomycin or gentamicin + teicoplanin) [biantibiotic case] and then tested against Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus (MRSA). Antibiotic elution and bacteria growth were measured every 24 h simultaneously by fluorescence polarization immunoassay and photometrically, respectively. The gentamicin + vancomycin combination achieved the longest growth inhibition on S. epidermidis and MRSA (mean of 20 and 14 days, respectively). Gentamicin + teicoplanin-loaded spacers were capable of inhibiting growth on E. faecalis and S. aureus for the longest period (11 and 16 days, respectively). The highest concentrations of gentamicin and vancomycin could be assayed during the first 4 days. Teicoplanin concentrations could be detected only during the first 72 h, synercid was not detected at all, possibly because of the limitation of the detection technique used. A greater percentage of the gentamicin was released than of the vancomycin. The aminoglycosid-glycopeptid combination showed a synergistic effect on the release of gentamicin, but not on vancomycin or teicoplanin. Biantibiotic-impregnated hip spacers proved to be superior to monoantibiotic ones. Because of important differences between the conditions used for the present tests and the in vivo environment, any recommendation with regard to the use of monoantibiotic- and biantibiotic-loaded acrylic bone cement spacers must await the results of further investigations.     

新型抗钙化牛颈静脉管道材料的体外细胞毒性评价

背景：Triton X-100、环氧氯丙烷联合改性处理戊二醛固定的牛颈静脉管道是一种新型抗钙化右心管道材料,其生物相容性方面的研究较少。 目的：评价新型抗钙化牛颈静脉管道的体外细胞毒性。 方法：通过CCK-8法检测新型抗钙化牛颈静脉管道(实验组)及单纯戊二醛处理牛颈静脉管道材料浸提液(对照组)对L-929小鼠成纤维细胞的毒性作用,以第2,4天为检测时间点,计算细胞相对增殖率、对材料毒性进行分级。 结果与结论：CCK-8法细胞毒性试验显示新型抗钙化牛颈静脉管道材料浸提液第2,4天L-929细胞增殖率均在85%以上,毒性分级为1级,无细胞毒性,且显著优于对照组(P < 0.05)。提示经戊二醛、Triton X-100、环氧氯丙烷联合处理制备的新型抗钙化牛颈静脉管道材料无细胞毒性。     

In vitro antibacterial activity of rokitamycin, a new macrolide antibiotic. Results of a multicenter study

Minimal inhibitory concentrations (MIC) of rokitamycin (R) were evaluated by agar dilution for 914 bacterial strain isolated in 4 hospitals and classed as a function of susceptibility and resistance to Macrolides-Lincosamides-Streptogramines group (MLS). MICs of R ranged from 0.06 to 1 microgram/ml (mode MIC 0.25-0.5) on Staphylococci susceptible to MLS and on MLSB inducible strains; R was inactive on MLSB constitutive strains. MICs of R ranged from 0.008 to 0.5 microgram/ml (mode MIC 0.06 to 0.25) for Streptococci and Pneumococci susceptible to erythromycin (E) and from 0.06 to greater than 128 for strains resistant to E. Enterococci susceptible to E were inhibited by 0.06 to 0.5 microgram/ml (mode MIC 0.5) and strains resistant to E by 0.25 to greater than 128. Haemophilus were inhibited by 0.5 to 0.65 microgram/ml (mode MICs of R ranged generally from 0.016 to 0.5 microgram/ml (mode MIC 0.12) for C. perfringens and from 0.016 to 1 (mode MIC 0.06) for B. fragilis. Thus, R was shown to be among macrolide antibiotics of resistance strains. Its activity was superior to that of other products of this group spiramycin, josamycin, miokamycin, particularly on Gram positive cocci. R had a good activity on Neisseria, Branhamella, anaerobes and, as others macrolides, was poorly active on Haemophilus.     

In vitro evaluation of CENTA, a new beta-lactamase-susceptible chromogenic cephalosporin reagent.

CENTA is a newly synthesized, beta-lactamase-labile, chromogenic cephalosporin reagent which changes color from light yellow (lambda maximum ca. 340 nm) to chrome yellow (lambda maximum ca. 405 nm) concomitant with hydrolysis of the beta-lactam ring. This compound offers promise as a diagnostic reagent comparable to other chromogens (PADAC and nitrocefin) for the early detection of beta-lactamase-producing clinical isolates, while retaining some antimicrobial effect against Escherichia coli, Klebsiella spp., Proteus mirabilis, Staphylococcus aureus, and non-enterococcal Streptococcus spp. CENTA is relatively unaffected by commonly used microbiological media and human serum.     

In vitro activity of the new glycopeptide decaplanin

The activity of decaplanin, a new glycopeptide, was compared to that of vancomycin, teicoplanin and daptomycin. Decaplanin was two- to four-fold less active than vancomycin, teicoplanin and daptomycin againstStaphylococcus aureus andStaphylococcus epidermidis, with an MIC90 of 2 µg/ml for methicillin-susceptible and 4 µg/ml for methicillin-resistant isolates. Decaplanin had activity similar to that of vancomycin againstStreptococcus pyogenes, Streptococcus agalactiae, group C and G streptococci, with an MIC90 of 0.12 µg/ml. It was less active than the other agents against the viridans group streptococci (MIC90 4 µg/ml). The activity of decaplanin against enterococci (MIC90 4 µg/ml) was similar to that of vancomycin.Clostridium spp. were inhibited by 0.5 µg/ml, peptostreptococci and peptococci by 0.25 µg/ml. Decaplanin was active from pH 5.5 to 7.5. Inoculum size had a minimal effect on MICs, and increased concentrations of Ca²⁺ and Mg²⁺ and 50 % serum did not alter MICs or MBCs.     

In vitro evaluation of the PUCA II intra-arterial LVAD

The "pulsatile catheter" (PUCA) pump is a minimally invasive intra-arterial left ventricular assist device intended for acute support of critically ill heart failure patients. To assess the hydrodynamic performance of the PUCA II, driven by an Arrow AutoCat IABP driver, we used a (static) mock circulatory system in which the PUCA II was tested at different loading conditions. The PUCA II was subsequently introduced in a (dynamic) cardiovascular simulator (CVS) to mimic actual in vivo operating conditions, with different heart rates and 2 levels of left ventricular (LV) contractility. Mock circulation data shows that PUCA II pump performance is sensitive to afterload, pump rate and preload. CVS data demonstrate that PUCA II provides effective LV unloading and augments diastolic aortic pressure. The contribution of PUCA II to total flow is inversely related to LV contractility and is higher at high heart rates. We conclude that, with the current IABP driver, the PUCA II is most effective in 1:1 mode in left ventricles with low contractility.     

In vitro evaluation of the TandemHeart pediatric centrifugal pump

The pediatric TandemHeart pump is being developed for short-term circulatory support of patients varying in size from 2 to 40 kg. The pump withdraws blood from the left atrium via cannula inserted percutaneously, either through the right internal jugular vein or transhepatically, and pumps the blood back into the arterial system via the carotid or femoral artery. High resolution stereolithography (SLA) was used to create an upper housing and impeller design, which were assembled into a functional pump prototype. Pressure-flow characteristics of the pump were determined in a blood analogue solution and compared with the pressure-flow requirements of the intended cannulation. At 5,500 rpm, the pump was able to generate 0.4 L/min of flow with a pressure rise of 325 mm Hg and 2.0 L/min with a pressure rise of 250 mm Hg. The hydraulic performance of the pump will enable at least 50% of cardiac output when the arterial cannula is placed in the carotid artery. The hemolysis of the TandemHeart pediatric pump at 5,500 rpm was compared with the BP-50 pediatric centrifugal pump in vitro using bovine blood flowing at 0.4 L/min against 250 mm Hg. The TandemHeart pump produced a similar increase in plasma free hemoglobin levels during the duration of the 6 hour test.     

In vitro antibiotic removal and bacterial recovery from blood with an antibiotic removal device.

The antibiotic removal device manufactured by Marion Laboratories (Kansas City., Mo.) is intended for treatment, before culture, of blood specimens from hospital patients being treated with antibiotics. Measurement of 13 antibiotics showed that the antibiotic removal device removed amikacin, ampicillin, carbenicillin, cefazolin, cephalothin, chloramphenicol, gentamicin, nafcillin, tetracycline, tobramycin, and vancomycin and reduced cefoxitin and ticarcillin to extremely low levels. Three combinations of antibiotics were similarly removed or reduced. Five species of anaerobic bacteria, one yeast species, and six species of facultative or aerobic bacteria were used to challenge the possibility that the antibiotic removal device would trap or inhibit microorganisms. All were recovered from the device in the same numbers as were inoculated.     

In vitro evaluation of a new drug combination against clinical isolates belonging to the Mycobacterium abscessus complex

The in vitro susceptibility profile to amikacin, linezolid, clarithromycin, imipenem, cefoxitin, clofazimine and tigecycline was established for 67 strains belonging to the Mycobacterium abscessus complex. Clofazimine and tigecycline were among the most effective drugs, prompting us to assess the effect of a clofazimine and tigecycline combination. Synergistic activity was found in 42% of the 19 isolates tested. The clinical impact of this new drug combination against the M. abscessus complex, as an alternative or sequential medication for the treatment of drug-resistant strains, remains to be addressed.     

In vitro evaluation of the hydraulic permeability of polysulfone dialysers

An in vitro set-up has been designed to study the hydraulic permeability of hollow fiber dialysers. Forward and reverse dialysate ultrafiltration were determined using both sterile dialysers and samples with a protein layer settled on the membrane (Fresenius F6, F8, F60 and F80). The ultrafiltration coefficient KUF (ml/h.mmHg) was calculated as the ratio of volumetrical flow (QUF) and transmembrane pressure (TMP) measurements. The protein layer on the membrane was induced either by recirculating human plasma through the dialysers (in vitro) or by a standard hemodialysis session (in vivo). KUF is largely independent of TMP up to 600mmHg (low flux) and 60mmHg (high flux) for forward and reverse flow In sterile dialysers, backfiltration yields a significantly different KUF except for the F80. An in vitro induced protein layer on the membrane decreases KUF15-30% (forward) and 4-12% (backward) in low flux and 45-70% (forward) and 65-73% (backward) in high flux dialysers.     

In vitro evaluation of antibiotic lock technique for the treatment of Candida albicans, C. glabrata, and C. tropicalis biofilms

Candidaemia associated with intravascular catheter-associated infections is of great concern due to the resulting high morbidity and mortality. The antibiotic lock technique (ALT) was previously introduced to treat catheter-associated bacterial infections without removal of catheter. So far, the efficacy of ALT against Candida infections has not been rigorously evaluated. We investigated in vitro activity of ALT against Candida biofilms formed by C. albicans, C. glabrata, and C. tropicalis using five antifungal agents (caspofungin, amphotericin B, itraconazole, fluconazole, and voriconazole). The effectiveness of antifungal treatment was assayed by monitoring viable cell counts after exposure to 1 mg/mL solutions of each antibiotic. Fluconazole, itraconazole, and voriconazole eliminated detectable viability in the biofilms of all Candida species within 7, 10, and 14 days, respectively, while caspofungin and amphotericin B did not completely kill fungi in C. albicans and C. glabrata biofilms within 14 days. For C. tropicalis biofilm, caspofungin lock achieved eradication more rapidly than amphotericin B and three azoles. Our study suggests that azoles may be useful ALT agents in the treatment of catheter-related candidemia.     

Comparative in vitro activity of biapenem,a new carbapenem antibiotic

Biapenem is a new carbapenem antibiotic with high stability to human renal dehydropeptidase I. Its in vitro activity was compared with that of imipenem, meropenem, ceftazidime, ceftriaxone, piperacillin and gentamicin against a total of 650 recent clinical isolates. MICs were determined by a standard agar dilution procedure and all isolates were tested at two inocula (10⁴ and 10⁶ cfu). Biapenem inhibited 90 % of isolates ofEscherichia coli, Klebsiella spp.,Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia stuartii, Enterobacter spp.,Citrobacter freundii, Serratia marcescens, Salmonella typhi, Shigella sonnei andYersinia enterocolitica at 2 mg/l and was as active as or two- to four-fold more active than imipenem against all these species, with the exception ofSerratia marcescens, against which imipenem was two-fold more active. Biapenem was two-fold more active than imipenem againstPseudomonas aeruginosa (MIC90 4 mg/l) and had activity similar to that of imipenem against theBacteroides fragilis group (MIC90 0.5 mg/l) but was two-fold less active than imipenem against methicillin-susceptibleStaphylococcus aureus (MIC90 0.06 mg/l) and was, like imipenem, inactive against methicillin-resistantStaphylococcus aureus.     

In vitro and in vivo evaluation of new PRP antibacterial moisturizing dressings for infectious wound repair

In this study, a solution chitosan fibroin emulsion with added Silver Nanoparticles (AgNPs) was freeze-dried to be the scaffold, and an asymmetric coating was formed on one side. PRP was loaded onto the composite scaffold using a secondary lyophilization technology to prepare the tissue engineering dressings. AgNPs were characterized using a transmission electron microscope. The morphologies of the composite dressing were examined under a scanning electron microscope. The silver content of the dressing was measured by inductively coupled plasma mass spectrometry. The asymmetric wettability of the composite dressing was demonstrated by water contact angle measurement. Relatively high porosity, favourable moisture retention capability and appropriate tensile strength were observed by measuring the physical and mechanical properties. Satisfactory antibacterial properties against various bacteria and microbial isolation performance were observed by the antibacterial effect analysis in vitro. The total protein slow-release property was measured using the BCA assay. Good biocompatibility and lower sensitization were examined both in vitro and in vivo. In addition, the healing effciency of the composite dressing on infected wound were examined in mice infected wound models. Analysis of wound healing rates, bacterial cultures of wound exudate, whole blood cell analysis and histological examination all showed satisfactory results. These results are demonstrated to provide a potential and possible pathway to promote wound tissue repair and regeneration.