Antimicrobial Activity of Cefamandole Against Salmonella typhi

A patient with Salmonella typhi bacteremia was sucessfully treated with cefamandole, a new cephalosporin derivative. Infection has not recurred during 6 months of follow-up observation. Minimum inhibitory concentrations and minimum bactericidal concentrations of cefamandole, cephalothin, ampicillin, and chloramphenicol were compared against 26 strains of S. typhi. All the strains were susceptible to cefamandole in vitro. Seven of the strains were resistant to chloramphenicol, and another seven were resistant to both chloramphenicol and ampicillin. Cefamandole appears to warrant further clinical trial for the treatment of typhoid fever.     

In Vitro Activity of Rosamicin Against Neisseria and Haemophilus, Including Penicillinase-Producing Strains

Rosamicin was significantly more active against Haemophilus and Neisseria than are many antibiotics currently used to treat or prevent infection caused by these organisms. This enhanced activity was also observed against penicillinase-producing strains.     

Comparative In Vitro Activity of Five Cephalosporins Against Lactobacilli

Of five parenteral cephalosporins tested against 43 lactobacilli, cephaloridine, cefazolin, and cefamandole were the most active inhibitory and bactericidal agents. Timed-kill analysis revealed a slow bactericidal effect, with significant declines in mean minimal bactericidal concentration values at 48 h versus 24 h.     

Comparative In Vitro Activity of Five Cephalosporin Antibiotics Against Salmonellae

The in vitro activities of five cephalosporin antibiotics against 121 strains of salmonellae were compared. Cefamandole and cefaclor were more potent than cefazolin, and these three drugs were more active than cephalothin and cephalexin.     

Comparative In Vitro Activity of Newer Cephalosporins Against Anaerobic Bacteria

The in vitro susceptibilities of 408 recent clinical isolates of anaerobic bacteria against cefaclor, cephalexin, cephalothin, cefazolin, cefamandole, and cefoxitin were compared by an agar dilution technique. Against gram-positive bacteria, especially peptococci, peptostreptococci, and propionibacteria, cephalexin and cefaclor were significantly less active than cephalothin (P < 0.05). Cephalexin was also less active than cephalothin against clostridia and lactobacillus (P < 0.05). Against gram-negative bacteria, major differences were observed primarily with Bacteroides fragilis, against which cephalexin, cefazolin and cefoxitin were all significantly more active than cephalothin (P < 0.001). At concentrations of 16 μg per ml, however, all cephalosporins showed high in vitro activity, except against Lactobacillus species and B. fragilis. Cephalothin, cefazolin and cefamandole were considerably more active against the former, whereas cefoxitin was distinctly more active against the latter.     

In Vitro Activity of Cinoxacin, Ampicillin, and Chloramphenicol Against Shigella and Nontyphoid Salmonella

The in vitro antibacterial activity of cinoxacin was compared with that of ampicillin and chloramphenicol against 26 strains of nontyphoid Salmonella and 44 strains of Shigella. Cinoxacin was found to have a lower minimal inhibitory concentration than ampicillin and chloramphenicol against all Salmonella and Shigella sonnei strains. Cinoxacin had minimal inhibitory concentrations similar to those of chloramphenicol but lower than those of ampicillin against Shigella flexneri and S. boydii strains.     

Comparative In Vitro Activity of Pirbenicillin, Ticarcillin, and Carbenicillin Against Pseudomonas aeruginosa

Pirbenicillin, a semisynthetic penicillin, showed greater in vitro activity against 68 recent isolates of Pseudomonas aeruginosa than did ticarcillin or carbenicillin. The median minimum inhibitory concentration of each of these three compounds, respectively, was 3.1, 12.5, and 25 mug/ml when a 10(-4) dilution of an overnight culture (about 10(5) colony-forming units [CFU]/ml) was used as inoculum, but these differences were less striking when larger inocula were used: at 10(7) CFU/ml these values were 6.25, 12.5, and 50 mug/ml, and at 10(8) to 10(9) CFU/ml these values were 50, 50, and 100 mug/ml. All three compounds showed greater inhibitory activity at pH 6 than at pH 8. This pH effect was greatest with pirbenicillin, for 6.25 mug of pirbenicillin per ml inhibited 7, 11, and 57% of the strains at pH 6, 7, and 8, respectively; these values were 4, 4, and 11% with ticarcillin and 0, 0, and 7% with carbenicillin. At sufficient inhibitory concentrations, the rates of bacterial killing of the three compounds were similar. The observed differences in anti-pseudomonad activity were not due to differences in stability to pseudomonad beta-lactamases, but all three compounds were more stable than were cefazolin, cephaloridine, and benzylpenicillin.     

Comparative In Vitro Activity of New Beta-Lactam Antibiotics Against Anaerobic Bacteria

Several new beta-lactam antimicrobial agents have been introduced in the last few years. In this investigation, the in vitro activities of several recently introduced cephalosporins (cefoperazone, cefotaxime, ceftazidime, and ceftizoxime), moxalactam, and N-formimidoyl thienamycin were compared with those of cefoxitin, clindamycin, and metronidazole against 203 strains of anaerobic bacteria. At achievable serum levels, all of the antimicrobial agents were active against essentially 100% of the strains of anaerobic gram-positive cocci, Clostridium perfringens, Leptotrichia buccalis, and species of Selenomonas, Veillonella, and Eubacterium. Clindamycin, metronidazole, and N-formimidoyl thienamycin were the most active agents against the Bacteroides fragilis group, inhibiting all strains at concentrations which can be achieved in serum. Of the remaining agents tested against the B. fragilis group, cefoxitin (which required 64 μg/ml to inhibit 90% of the strains) was the most active, followed by cefoperazone (128 μg/ml), cefotaxime (128 μg/ml), moxalactam (128 μg/ml), ceftizoxime (256 μg/ml), and ceftazidime (>256 μg/ml). Important differences in cephalosporin susceptibility among species of the B. fragilis group were observed. Metronidazole and N-formimidoyl thienamycin were the most active drugs against species of clostridia other than C. perfringens; the other antibiotics displayed poor activity, although this is partly due to inclusion of a relatively large number of strains of Clostridium difficile which were very resistant to several of the cephalosporins. Only metronidazole was active against all species of Fusobacterium. Clindamycin and N-formimidoyl thienamycin displayed excellent activity against gram-positive, non-spore-forming bacilli, requiring ≤8 μg/ml to inhibit 100% of the strains. Ceftazidime, cefoperazone, and moxalactam were bactericidal for 25 strains of B. fragilis at concentrations equal or close to those required for inhibition. On the basis of its activity in vitro, N-formimidoyl thienamycin appears to be the most promising of the new beta-lactam antibiotics for the treatment of infections involving anaerobic bacteria.     

Comparative In Vitro and Bactericidal Activity of Oxazolidinone Antibiotics Against Multidrug-Resistant Enterococci

Increasing resistance among enterococci poses a considerable therapeutic problem. In this study, we evaluated the comparative in vitro activity of two investigational oxazolidinone antibiotics, eperezolid and linezolid, versus clinical isolates of multidrug-resistant enterococci. One hundred isolates (16 Enterococcus faecalis, 69 E. faecium, 10 E. gallinarum, 2 E. casseliflavus, 1 E. avium, 1 E. hirae, and 1 E. raffinosus) evaluated were collected from diverse geographic areas in North America and Europe from 1991 to 1995. Eperezolid MIC₅₀ and MIC₉₀ were 1.0 μg/mL and 2.0 μg/mL (1.0–2.0 μg/mL range). Linezolid MIC₅₀ and MIC₉₀ were 2.0 μg/mL and 2.0 μg/mL (0.5–2.0 μg/mL range), respectively. MICs were the same at 10³ CFU/mL and 10⁸ CFU/mL initial inoculum. In time-kill experiments using 10 strains and concentrations of 4 μg/mL, 8 μg/mL, and 16 μg/mL (achievable serum concentrations) of eperezolid and linezolid, there was a 2 log₁₀ reduction of growth for 2 of 10 isolates tested using eperezolid and a 1 log₁₀ reduction for 50% of isolates with both agents. There was indifferent bactericidal killing when either oxazolidinone was combined with gentamicin, ampicillin, or streptomycin for isolates lacking these resistances. This study demonstrates these oxazolidinone agents to have excellent in vitro activity versus multidrug-resistant enterococci.     

In Vitro Activity of Penicillins Against Anaerobes

The in vitro susceptibility of 162 anaerobic isolates from clinical material were tested to pencillin G, BL-P1654, and carbenicillin. Penicillin G and BL-P1654 showed good activity against Bacteroides fragilis, but only 60% of strains were susceptible to carbenicillin at achievable blood levels (128 μg/ml).     

Piperacillin: In Vitro Evaluation

The in vitro activity of a new semisynthetic penicillin, piperacillin, was determined against 577 clinical isolates of gram-positive cocci and gram-negative bacilli. A concentration of 12.5 mug/ml inhibited 92% of isolates of Pseudomonas aeruginosa, 82% of Serratia marcescens, 73% of Escherichia coli, 61% of Klebsiella spp., and 42% of Enterobacter spp. Most Proteus spp. were extremely susceptible; over 85% were inhibited by 0.10 mug/ml. Piperacillin failed to inhibit the growth of gram-negative bacilli when large inocula were used. The type of media and pH had variable effects on the activity of piperacillin, depending upon the organism. Piperacillin was generally less active than PC-904 against gram-negative bacilli, but was consistently more active than carbenicillin and ticarcillin.     

Comparative Evaluation of Piperacillin in Vitro

The minimal inhibitory concentrations of piperacillin and seven other betalactam antibiotics were determined against 407 bacterial isolates. Piperacillin was found to be more active than ampicillin against susceptible gram-negative bacilli and more active than either carbenicillin or ticarcillin against Pseudomonas aeruginosa and streptococci. Although piperacillin was active against Klebsiella pneumoniae, this activity was less than that of the cephalosporins. Piperacillin was not active against penicillin-resistant Staphylococcus aureus and Enterobacteriaceae that were resistant to the other test antibiotics.     

In Vitro Activity of Piperacillin Compared with That of Carbenicillin, Ticarcillin, Ampicillin, Cephalothin, and Cefamandole Against Pseudomonas aeruginosa and Enterobacteriaceae

Piperacillin (T-1220), a semisynthetic derivative of aminobenzylpenicillin, was more active than either carbenicillin or ticarcillin against Pseudomonas aeruginosa; over 60% of isolates were inhibited at a concentration of 6.3 mug/ml. Piperacillin was bactericidal for 84% of Pseudomonas strains at 100 mug/ml, carbenicillin killed 60%, and ticarcillin killed 68% at that concentration. Piperacillin was also more active than the other penicillins against isolates of Escherichia coli, Enterobacter, and Proteus mirabilis. The combination of piperacillin and tobramycin, demonstrating synergistic inhibition of 87% of strains of P. aeruginosa, was the most active of the penicillin-aminoglycoside combinations tested for synergism.     

In Vitro Activity of Voriconazole Against Candida Species

The in vitro activity of voriconazole was compared with that of itraconazole and fluconazole against 181 isolates of Candida albicans, 124 isolates of Candida glabrata, and 20 isolates of Candida krusei obtained from the early 1980s through the mid-1990s. Voriconazole had greater intrinsic activity than fluconazole or itraconazole against all three Candida species. For C. glabrata, C. krusei, and C. albicans, the MIC₅₀ values for voriconazole were 1 μg/mL, 0.5 μg/mL, and 0.01 μg/mL, respectively, compared with fluconazole MIC₅₀ values of 8 μg/mL, 64 μg/mL, and 0.25 μg/mL, respectively. If isolates from AIDS patients were excluded, MIC values for isolates from the 1990s were no higher than those noted for isolates from the 1980s. Voriconazole, a new triazole antifungal agent, appears to have enhanced activity against these three species of Candida; the clinical relevance of these findings should be studied in treatment trials.     

Comparative In Vitro Activity of Azlocillin, Ampicillin, Mezlocillin, Piperacillin, and Ticarcillin, Alone and in Combination with an Aminoglycoside

The in vitro activities of the newer semisynthetic penicillins azlocillin, mezlocillin, and piperacillin were compared with those of ampicillin and ticarcillin by using 290 clinical laboratory isolates. Piperacillin and mezlocillin were the most active against Escherichia coli, Proteus mirabilis, Klebsiella spp., and Enterobacter spp. When Pseudomonas aeruginosa was tested, piperacillin and azlocillin were more active than either mezlocillin or ticarcillin. Streptococcus pneumoniae and Haemophilus influenzae species were highly susceptible to all of the penicillins tested. Ticarcillin had relatively poor activity against enterococci. The rate of bacterial killing with multiples of the minimal inhibitory concentration of azlocillin, ampicillin, or ticarcillin was tested for E. coli, P. mirabilis, P. aeruginosa, and Klebsiella spp. Increasing concentrations increased the bactericidal effect. The effect of combining azlocillin, ampicillin, or ticarcillin with an aminoglycoside was studied by using both killing curves and checkerboards. The isobolograms constructed from the checkerboards showed a synergistic pattern for the organisms tested, which included E. coli, P. aeruginosa, Klebsiella spp., P. mirabilis, and enterococci. However, the rate of killing was increased by the combination only for P. aeruginosa and enterococci.     

In Vitro Activity of Rosaramicin Against Chlamydia trachomatis

In vitro, rosaramicin was highly active against Chlamydia trachomatis when added to the culture system 1 or 48 h after inoculation with the chlamydia.     

DC-CIK细胞的生物学活性及体外抗白血病作用的研究

本研究探讨树突状细胞（DC）对细胞因子诱导的杀伤细胞（CIK）增殖能力、免疫表型、分泌细胞因子水平及抗白血病细胞的作用。健康人外周血单个核细胞诱导DC和CIK，将DC与CIK共培养，以CIK细胞单独培养为对照。用台盼蓝活细胞计数计算细胞扩增倍数，MTT法测定杀伤活性，流式细胞术分析免疫表型，ELISA双抗体夹心法测定干扰素-γ（IFN-γ）、白介素-12（IL—12）的水平。结果表明：DC—CIK细胞增殖能力明显高于CIK细胞（P〈0．05）；DC、CIK细胞共培养后，CD3^＋CD8^＋、CD3^＋CD56^＋细胞比率较相同条件下CIK细胞组显著增多（P〈0．05）；共培养3天，DC—CIK细胞上清液中IL-12、IFN-γ水平均比CIK细胞单独培养的水平高（P〈0．01，P〈0．05）；在5：1—40：1的效靶比范围内，DC—CIK细胞对白血病细胞的杀伤率显著高于CIK细胞（P〈0．05），且杀伤率与效靶比呈正相关。结论：DC增加CIK细胞的增殖能力和抗白血病活性，有可能作为一种临床有效的抗白血病免疫治疗手段。     

白藜芦醇体外抗白假丝酵母菌生物膜作用的初步研究

目的 研究白藜芦醇对体外白假丝酵母菌生物膜的影响.方法 采用XTT减低法评价白藜芦醇对白假丝酵母菌生物膜的影响;通过倒置显微镜、扫描显微镜观察该药对白假丝酵母菌生物膜的形态学影响.结果 白藜芦醇对白假丝酵母菌生物膜的SMIC50,SMIC80分别为128,256 μg/ml;当白藜芦醇浓度为256 μg/ml时对白假丝酵母菌的早期黏附及菌丝生长有抑制作用.结论 白藜芦醇对体外白假丝酵母菌生物膜有显著的抑制作用.     

In Vitro Activity of Cefotaxime Against Cephalothin-Resistant Clinical Isolates

Cefotaxime is more active than six other cephalosporins against 150 cephalothin-resistant Enterobacteriaceae strains and is the only drug which is more active than ampicillin against Haemophilus. It shows a potentially useful activity against Pseudomonas.