耐甲氧西林金黄色葡萄球菌体外抗菌活性研究

为给临床合理选用抗生素和有效控制耐甲氧西林金黄色葡萄球菌（ＭＲＳＡ）的感染提供依据，对ＭＲＳＡ的耐药特点进行了研究。测定了１７种抗生素对临床分离的７５株金黄色葡萄球菌的最低抑菌浓度和β－内酰胺酶。结果表明，临床分离菌的６６．７％为ＭＲＳＡ，ＭＲＳＡ中产β－内酰胺酶菌株占９２％。所有ＭＲＳＡ对青霉素Ｇ、氨苄青霉素和洁霉素耐药，但皆对万古霉素敏感，对丁胺卡那霉素、氟哌酸、氟嗪酸、环丙氟哌酸、头孢哌酮等敏感率大于５５％。ＭＲＳＡ耐抗生素种类数为５到１６种不等。对苯唑青霉素耐药水平越高，则耐抗生素种类数也越多，二者呈显著正相关（ｒ＝０．９３５３，Ｐ＜０．００５）。建议治疗ＭＲＳＡ感染首选万古霉素。     

Moxifloxacin: a comparison with other antimicrobial agents of in-vitro activity against Streptococcus pneumoniae

Two hundred representative isolates, including 26 strains of Streptococcus pneumoniae with intermediate resistance to penicillin, were selected from a collection obtained from blood cultures of patients with bacteraemic pneumococcal pneumonia. The MICs of moxifloxacin (BAY 12-8039), grepafloxacin, sparfloxacin, levofloxacin, ofloxacin, ciprofloxacin, erythromycin, tetracycline and penicillin G were determined by a standard agar dilution technique. Moxifloxacin had the highest in-vitro activity against S. pneumoniae (MIC90 = 0.25 mg/L; MIC range 0.06-0.25 mg/L). The MIC90 values were one dilution lower than those obtained with sparfloxacin and grepafloxacin, three dilutions lower than those obtained with levofloxacin, and four dilutions lower than those of ofloxacin and ciprofloxacin.     

Comparative in-vitro activity of four peptide antibiotics against penicillin-resistant Streptococcus pneumoniae isolated from cerebrospinal fluid (CSF).

The in-vitro activity of four peptide antibiotics against 43 penicillin-resistant Streptococcus pneumoniae isolated from cerebrospinal fluid (CSF) was evaluated. The activity of SKF104662 was slightly greater to that of vancomycin, teicoplanin and daptomycin (MICs for 90% of the isolates tested 0.06, 0.25, 0.12 and 0.25 mg/L, respectively) and superior to the other 15 drugs tested. The serotype of these penicillin-resistant strains was also determined. The strains that belonged to the predominant serotype 9 were resistant only to penicillin. All six erythromycin- and clindamycin-resistant strains belonged to serotype 6 and three of them were also resistant to chloramphenicol and tetracycline (plus penicillin).     

Penicillin-netilmicin synergism against Streptococcus faecalis.

The combination of penicillin plus netilmicin was synergistic in vitro against 28 strains of Streptococcus faecalis and compared favorably with penicillin in combination with gentamicin. Similarly, penicillin plus netilmicin was as effective as penicillin plus gentamicin in the therapy of 67 rabbits with enterococcal endocarditis produced with a streptomycin-susceptible (S) or a streptomycin-resistant (R) strain of S. faecalis. After 5 days of infection, control rabbits had bacterial titers of 10(10) colony-forming units (CFU)/g of vegetation. Those treated with penicillin plus netilmicin had mean titers of 10(5.2) and 10(5.1) CFU/g for S and R strains, respectively, and those treated with penicillin plus gentamicin had mean valve titers of 10(5.8) CFU/g for both strains. After 10 days of therapy, mean valve titers with penicillin plus netilmicin were 10(3.8) and 10(4.7) CFU/g, and with penicillin plus gentamicin they were 10(4.5) and 10(5.4) CFU/g for S and R strains, respectively. Thus, if netilmicin proves to be less toxic than other aminoglycoside antibiotics, it may have potential usefulness in the therapy of enterococcal endocarditis.     

A comparison of the in-vitro activity of some 5-nitroimidazoles and other compounds against Giardia intestinalis

The activities of 11 5-nitroimidazole compounds have been compared against Giardia intestinalis in vitro using a 3H-thymidine incorporation assay. All the compounds were at least equipotent to, or more active than metronidazole with the exception of panidazole. Satranidazole, ronidazole and S75 0400 A were all about five times more active than metronidazole and warrant further study as potential chemotherapeutic agents for man. No major differences in the response to these compounds was found between two stocks of Giard. intestinalis with the exception of flunidazole. Several other antiprotozoal drugs showed activity against Giard. intestinalis. Berberine sulphate, paromomycin sulphate, erythromycin estolate and sulphasalazine, all of which have been used to treat human patients, showed no activity in vitro.     

Comparative in-vitro activity of carbapenem antibiotics against respiratory pathogens isolated between 1999 and 2000

We investigated the antibacterial activity of 12 antibiotics, inclusive of four carbapenems, against 167 strains of respiratory pathogens isolated between 1999 and 2000. Thirty strains of methicillin-susceptible Staphylococcus aureus (MSSA), 28 strains of methicillin-resistant S. aureus (MRSA), 11 strains of penicillin-susceptible Streptococcus pneumoniae (PSSP), 29 strains of penicillin-resistant S. pneumoniae (PRSP), 30 strains of Pseudomonas aeruginosa, 14 strains of Moraxella catarrhalis, and 25 strains of Haemophilus influenzae were examined. The minimum inhibitory concentration (MICs)_50/90 (μg/ml) of imipenem, panipenem, meropenem, and biapenem against the clinical isolates obtained between 1999 and 2000 were: 0.06/0.25, 0.12/0.25, 0.12/0.25, and 0.12/0.25, respectively, against MSSA; 16/32, 16/32, 16/32, and 8/32 against MRSA; ≦0.015/0.06, ≦0.015/0.03, 0.03/0.12, and ≦0.015/0.06 against PSSP; 0.12/0.25, 0.03/0.06, 0.25/0.5, and 0.12/0.25 against PRSP; 1/8, 2/8, 0.5/2, and 2/16 against P. aeruginosa; 0.06/0.06, 0.03/0.06, ≦0.015/0.06, and 0.06/0.12 against M. catarrhalis; and 1/4, 1/4, 0.12/0.25, and 2/4 against H. influenzae. A comparison of the antibacterial activity of the four carbapenems with that found in our previous studies showed no significant difference in the susceptibility of clinical isolates, except for a slight decrease in the susceptibility of MSSA. Carbapenems have remained effective for severe infections. The MIC data showed that imipenem and panipenem were more active than meropenem and biapenem against gram-positive bacteria, and that meropenem and biapenem were more active than imipenem and panipenem against gram-negative bacteria. As only meropenem had an MIC₉₀ below the breakpoint of pneumonia against all species except MRSA, meropenem was considered to be the most potent of the four carbapenems studied. Received: February 8, 2001 / Accepted : June 5, 2001     

Comparative in-vitro activity of LY146032 and eight other antibiotics against gram-positive bacteria isolated from children

LY146032, a cyclic peptide antibiotic active against many Gram-positive bacteria, was compared to methicillin, vancomycin, clindamycin, cefuroxime and gentamicin against methicillin-resistant and methicillin-susceptible strains of Staphylococcus aureus and Staph. epidermidis. LY146032 was uniformly active against clinical isolates of staphylococci, inhibiting 90% of strains of Staph. aureus and Staph. epidermidis at a concentration of 0.5 mg/l. Vancomycin was slightly less active than LY146032 against Staph. aureus and Staph. epidermidis, inhibiting 90% of strains at concentrations of 1.0 and 2.0 mg/l, respectively. All other antibiotics tested were less active than LY146032 or vancomycin against staphylococci. LY146032 was compared to penicillin, ampicillin, vancomycin and chloramphenicol against strains of Streptococcus pneumoniae, group B streptococcus, group D streptococcus (enterococcus) and Listeria monocytogenes and was found to inhibit 90% of the strains at concentrations of 0.25, 1.0, 32.0 and 16.0 mg/l respectively. The combination of LY146032 and chloramphenicol was antagonistic in vitro for one strain each of Staph. aureus and group D streptococcus and showed indifference against other strains of Staph. aureus(2), Staph. epidermidis(2), group D streptococcus(1) and L. monocytogenes(2). LY146032 in combination with gentamicin showed indifference against the same bacteria. On the basis of its in-vitro activity, LY146032 appears to be a promising agent for the treatment of serious community- and hospital-acquired staphylococcal infections.     

A comparison of the in-vitro activity of antimicrobials against Chlamydia trachomatis examined by Giemsa and a fluorescent antibody stain

Minimum concentrations for the inhibition of normal chlamydial inclusions (MICN) and abnormal inclusions (MICA) were obtained for a range of antimicrobials titrated against Chlamydia trachomatis in McCoy cell cultures. Each antibiotic titrated produced an MICN which was the same whether examined by Giemsa or fluorescent antibody staining methods (rifampicin 0.007 mg/l, tetracycline, erythromycin and penicillin 0.062 mg/l, chloramphenicol and spiramycin 0.25 mg/l, ciprofloxacin 1.0 mg/l, and cycloserine 250 mg/l). With the exception of penicillin the MICA (Giemsa) was between two- and four-fold higher than the MICN, and the MICA (fluorescent antibody) a further two-fold higher. Penicillin was alone in the wide concentration range over which abnormal inclusions were detected (0.0062 mg/l to 5 g/l).     

A comparison of the activity of tigecycline against multiresistant clinical isolates of Staphylococcus aureus and Streptococcus agalactiae

We evaluated the activity of several antibiotics against 225 clinical isolates of Staphylococcus aureus and 252 isolates of Streptococcus agalactiae. Only tigecycline, glycopeptides, and linezolid were active against all the isolates of S. aureus, whereas the beta-lactams were also active against S. agalactiae. Tigecycline could be a good alternative to ampicillin in the treatment of group B Streptococcus infections in patients allergic to beta-lactam.     

Binding of beta-lactam antibiotics to penicillin-binding proteins of Staphylococcus aureus and Streptococcus faecalis: relation to antibacterial activity.

The binding of 14 structurally diverse beta-lactam antibiotics to penicillin-binding proteins of Staphylococcus aureus and Streptococcus faecalis was studied, and the results were examined in the context of the antibacterial activity of the compounds. Penicillin-binding proteins 1 (molecular weight, 87,000) and 3 (molecular weight, 75,000) of S. aureus and penicillin-binding proteins 1 (molecular weight, 105,000) and 3 (molecular weight, 79,000) of S. faecalis bound beta-lactam antibiotics at concentrations comparable to minimum inhibitory concentrations and might therefore be essential. The low affinity of S. faecalis penicillin-binding proteins, relative to that of S. aureus penicillin-binding proteins, toward most beta-lactam antibiotics is probably responsible for the resistance of the former organism to most of these compounds.     

Comparative in-vitro activity of ciprofloxacin against non-fermenters

The in-vitro activity of ciprofloxacin, a quinolone-carboxylic acid derivative, was compared with those of carbenicillin, azlocillin, cefsulodin, ceftazidime, tobramycin and amikacin against 187 non-fermenters. Only one of the 131 strains of Pseudomonas spp. was not inhibited by 1 mg/l of ciprofloxacin, while these isolates appeared highly resistant to carbenicillin, azlocillin and cefsulodin. Ciprofloxacin was also the best agent against Flavobacterium, Alcaligenes faecalis and Acinetobacter calcoaceticus with MIC90's respectively of 0.5, 4 and 8 mg/l. This new compound appeared bactericidal, and we found a small or no inoculum effect with ciprofloxacin.     

Comparative in-vitro activity of antibiotics incorporated in acrylic bone cement

We compared the persistence of antibacterial activity around antibiotic-impregnated acrylic bone cement discs which were serially transferred on seeded agar plates. On plates inoculated with Staphylococcus aureus ATCC 25923, CMW1 discs containing 2.5% by dry weight of cephalothin, coumermycin or fusidic acid (as diethanolamine fusidate) produced zones of inhibition for four to eight weeks when transferred daily. In contrast, ceftriaxone, cotrimoxazole, rifampicin and vancomycin ceased to be inhibitory within a week. Discs made of 'Palacos-R with Garamycin,' which contains gentamicin 1.25%, had an intermediate duration of activity. When Escherichia coli ATCC 25922 was used as the test organism, ceftriaxone and 'Palacos-R with Garamycin' showed activity for almost three weeks, cephalothin and cotrimoxazole were briefly inhibitory and the remainder not at all. When discs were transferred each week instead of daily, the ranking of antibiotics was similar but antibacterial activity persisted for longer. A combination of gentamicin plus fusidic acid in CMW1 was active for a much shorter time than either fusidic acid alone or 'Palacos-R with Garamycin'. We conclude that coumermycin is a promising new agent for incorporation in acrylic cement.     

In vitro activity of telithromycin against Streptococcus pneumoniae resistant to other antibiotics, including cefotaxime

A total of 407 isolates of Streptococcus pneumoniae, most of which were resistant to one or more antibiotics, were tested for susceptibility to telithromycin and four other agents. Telithromycin was the most active agent tested, with 98% of isolates susceptible to < or = 1.0 mg/L. For strains resistant to the other antibiotics, susceptibility to telithromycin ranged from 98.6% for strains resistant to trimethoprim/sulfamethoxazole to 94.4% for strains resistant to cefotaxime.     

In-vitro activity of seventeen antimicrobial compounds against seven species of mycobacteria

Within attainable serum concentrations, quinolones, especially ciprofloxacin, inhibited strains of Mycobacterium tuberculosis, M. xenopi, M. kansasii, M. fortuitum and M. marinum; vancomycin inhibited M. tuberculosis, the M. avium-intracellulare-scrofulaceum complex. M. kansasii, M. xenopi and M. chelonei; erythromycin was active against M. kansasii, M. xenopi and M. fortuitum, minocycline against M. kansasii and M. marinum and netilmicin and cefuroxime against M. xenopi. Aztreonam showed some activity against M. tuberculosis but little or no effect was shown by five cephalosporins or imipenem.     

Comparative in-vitro activity of five fluoroquinolones against mycobacteria

Fifty distinct strains of mycobacteria were investigated to determine their in-vitro susceptibility to five new fluoroquinolones (norfloxacin, pefloxacin, ofloxacin, enoxacin and ciprofloxacin). Ofloxacin and ciprofloxacin were found to be the most active, with minimum inhibitory concentrations (MIC) of 1.25 mg/l or less to all strains of Mycobacterium tuberculosis, M. bovis, M. xenopi, M. kansasii and BCG tested. All agents showed little activity against M. malmoense and M. avium-intracellulare complex with MIC values of greater than 2.5 mg/l.