In vitro activity of ramoplanin against vancomycin-resistant gram-positive organisms.

In vitro activity of ramoplanin, a cyclic lipoglycopeptide, against 92 vancomycin-resistant gram-positive organisms was evaluated. Ramoplanin demonstrated potent activity against many highly vancomycin-resistant organisms including enterococci (MICs for 90% of strains tested of 0.5 micrograms/ml) and against Lactobacillus spp., Leuconostoc spp., and Pediococcus spp., all of which were inhibited at concentrations of < or = 0.25 micrograms/ml. This drug or a derivative compound merits further investigation as a potential therapeutic agent for infections due to vancomycin-resistant enterococci.     

利奈唑胺对革兰阳性球菌的体外抗菌活性研究

目的 检测利奈唑胺对临床分离的金黄色葡萄球菌、表皮葡萄球菌、溶血葡萄球菌、粪肠球菌、屎肠球菌等革兰阳性球菌的体外扰菌活性.为临床合理使用抗生素提供依据.方法 采用VITEK-32全自动微生物分析仪和ATB自动微生物分析仪鉴定和药敏系统对临床分离的常见革兰阳性球菌267株进行鉴定和药敏试验.根据其药敏结果 比较8种抗菌药物对葡萄球菌、肠球菌的抗菌活性.结果 在临床分离的267株菌中金黄色葡萄球菌111株,MRSA 74株(占66.7%).凝同酶阴性葡萄球菌96株(表皮葡萄球菌57株、溶血葡萄球菌39株),MRCNS有80株(占86.0%),粪肠球菌45株,屎肠球菌13株.利奈唑胺对207株葡萄球菌、58株肠球菌体外抗菌活性分别为100%、93.1%,与万古霉素相当,明显高于其他常用的抗生索(如红霉素、头孢唑林、环丙沙星等).其对金黄色葡萄球菌、凝同酶阴性葡萄球菌、肠球菌的MIC50和MIC90分别为1,1mg/L;1,1mg/L;2,4mg/L.结论 耐甲氧西林葡萄球菌发生率高,多重耐药严重,利奈唑胺对葡萄球菌的抗菌活性与万占霉索相当,对肠球菌也有较强的抗菌活性.葡萄球菌、肠球菌对左氧氟沙星、四环素、红霉素均产生了不同程度的耐药性.     

利奈唑胺对革兰阳性球菌的体外抗菌活性研究

目的检测利奈唑胺对临床分离的金黄色葡萄球菌、表皮葡萄球菌、溶血葡萄球菌、粪肠球菌、屎肠球菌等革兰阳性球菌的体外抗菌活性,为临床合理使用抗生素提供依据。方法采用VITEK-32全自动微生物分析仪和ATB自动微生物分析仪鉴定和药敏系统对临床分离的常见革兰阳性球菌267株进行鉴定和药敏试验．根据其药敏结果比较8种抗菌药物对葡萄球菌、肠球菌的抗菌活性。结果在临床分离的267株菌中金黄色葡萄球闺111株,MRSA74株（占66．7％）,凝同酶阴性葡萄球菌96株（表皮葡萄球菌57株、溶血葡萄球菌39株）,MRCNS有80株（占86．0％）,粪肠球菌45株、屎肠球菌13株。利奈唑胺对207株葡萄球菌、58株肠球菌体外抗菌活性分别为100％,93．1％,与万古霉素相当,明显高于其他常用的抗生素（如红霉素、头孢唑林、环丙沙星等）。其对金黄色葡萄球菌、凝固酶阴性葡萄球菌、肠球菌的MIC50和MIC90分别为1．1mg／L;1.1mg／L：2.4mg／L。结论耐甲氧西林葡萄球菌发生率高,多重耐药严重,利奈唑胺对葡萄球菌的抗菌活性与万古霉素相当．对肠球菌也有较强的抗菌活性。葡萄球菌、肠球菌对左氧氟沙星、四环素、红霉素均产生了不同程度的耐药性。     

In vitro activity of the trinem sanfetrinem (GV104326) against gram-positive organisms.

The in vitro activity of the trinem sanfetrinem (formerly GV104326) (GV) was compared with that of vancomycin, ampicillin, and/or nafcillin against 287 gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and multiresistant enterococci, by the agar and microbroth dilution methods. GV demonstrated 2 to 16 times more activity than ampicillin and nafcillin against the majority of these organisms. The MIC range of GV was 16 to 64 micrograms/ml for 19 Enterococcus faecium strains that were highly resistant to ampicillin (ampicillin MIC range, 64 to 512 micrograms/ml) and vancomycin resistant and 0.25 to 32 micrograms/ml for resistant Rhodococcus spp. Similar activities (+/-1 dilution) were observed by either the agar or the broth microdilution method. GV demonstrated bactericidal activity against a beta-lactamase-producing Enterococcus faecalis strain and against two methicillin-susceptible Staphylococcus aureus strains in 10(5)-CFU/ml inocula. Synergy between GV and gentamicin was observed against an E. faecalis strain that lacked high-level gentamicin resistance. The activity of GV suggests this compound warrants further study.     

In vitro activity of linezolid against Clostridium difficile

We examined the in vitro activity of linezolid against Clostridium difficile, including isolates with reduced susceptibility to metronidazole or vancomycin. The MIC at which 50% of the isolates were inhibited (MIC50) and MIC90 were 0.5 and 2 microg/ml, respectively (range, 0.03 to 4 microg/ml). MICs were always 相似文献   

In vitro activity of levofloxacin against gram-positive bacteria

The in vitro activity of levofloxacin was investigated against 256 clinical strains of four gram-positive genera (Staphylococcus, Streptococcus, Enterococcus, and Listeria). Ofloxacin and ciprofloxacin were used as comparators. Uniform susceptibility to levofloxacin was recorded among methicillin-susceptible staphylococci, streptococci other than Streptococcus agalactiae, regardless of their being susceptible, intermediate, or resistant to penicillin (S. pneumoniae) or erythromycin (S. pyogenes and S. pneumoniae), in enterococci other than Enterococcus faecalis and E. faecium, and in Listeria monocytogenes isolates. Moreover, 1 of 22 S. agalactiae isolates and 1 of 19 E. faecium isolates was resistant, and 2 of 19 were intermediate. Resistances to levofloxacin with MIC90s in the resistance range were only observed in methicillin-resistant staphylococci and E. faecalis isolates. In any case, the MICs of ofloxacin and ciprofloxacin were usually 2-4 times higher than those of levofloxacin. In time-kill assays using three test strains (a methicillin-susceptible Staphylococcus aureus isolate, a penicillin-susceptible Streptococcus pneumoniae isolate, and an E. faecalis isolate), the bactericidal activity of levofloxacin was greater than that of ciprofloxacin. Copyright Copyright 1999 S. Karger AG, Basel.     

Activity of linezolid against 3,251 strains of uncommonly isolated gram-positive organisms: report from the SENTRY Antimicrobial Surveillance Program

Linezolid was tested against 32 species of uncommonly isolated gram-positive organisms (3,251 strains) by reference MIC methods and found to be highly active (MIC50 range, 0.25 to 2 microg/ml; MIC90 range, 0.25 to 2 microg/ml). Only one isolate (viridans group streptococcus; 0.03% of tested strains) was resistant to linezolid.     

LEADER surveillance program results for 2006: an activity and spectrum analysis of linezolid using clinical isolates from the United States (50 medical centers)

Surveillance for emerging linezolid resistance among commonly occurring Gram-positive pathogens in the United States began with the 2002 ZAAPS program and more recently (2004) expanded as the LEADER program. The 2006 LEADER program processed 5374 strains from 50 medical centers (100 per site) located within the 9 US census regions; species and number tested by broth microdilution (% linezolid susceptible) included Staphylococcus aureus (2913, >99.9), coagulase-negative staphylococci (CoNSs) (808, 98.4), enterococci (547, 97.4), Streptococcus pneumoniae (546, 100.0), viridans group streptococci (189, 100.0), and beta-hemolytic streptococci (371, 100.0). In addition to 1 linezolid-nonsusceptible S. aureus, 3 strains were daptomycin-nonsusceptible, 4 were quinupristin/dalfopristin-intermediate, 2 were vancomycin-intermediate (vancomycin MIC values, 4 mug/mL), and all were methicillin-resistant S. aureus. Among the linezolid-resistant isolates (1 S. aureus, 13 CoNSs, 3 Enterococcus faecalis, and 10 Enterococcus faecium isolates), all but 3 Staphylococcus epidermidis isolates had the G2567T mutation. Overall, 99.55% of the tested 2006 LEADER program isolates remained susceptible to linezolid at current Clinical and Laboratory Standards Institute breakpoints.     

In vitro activity of LY146032 against gram-positive bacteria

The activity of LY146032 (LY) was evaluated against 269 clinical isolates: 150 Staphylococcus spp. (Staph), 45 enterococci, 51 Clostridium spp., and 23 peptostreptococci. LY was compared to penicillin, metronidazole, imipenem, clindamycin, oxacillin, ciprofloxacin, vancomycin, and ampicillin. LY and oxacillin were tested against Staph by microdilution in cation-supplemented Mueller-Hinton broth (CSMHB), and in unsupplemented Mueller-Hinton broth (MHB). For LY, the MIC 90s in CSMHB were 16-32 dilutions lower. Among the Staph, the MIC 90s for LY, vancomycin, and ciprofloxacin were 4 micrograms/ml, 4 micrograms/ml, and 2 micrograms/ml respectively. The MIC 90s for enterococci by agar dilution were as follows: LY 8 micrograms/ml; ampicillin 4 micrograms/ml; imipenem 4 micrograms/ml; vancomycin 4 micrograms/ml; and ciprofloxacin 2 micrograms/ml. Clindamycin and penicillin were the most effective drugs against peptostreptococci and Clostridia spp., but LY was the most active drug against Clostridium difficile. The bactericidal activity of LY was determined by 24-hr time-kill curves in MHB. These showed a bactericidal effect against enterococci, and a bacteriostatic effect against three of four strains of Staph. Synergy was demonstrated against enterococci and Staph when LY was tested with aztreonam, ceftriaxone, or tobramycin. LY is a promising new agent against gram-positive bacteria, including methicillin resistant strains of staphylococci and enterococci.     

In vitro activity of telavancin against resistant gram-positive bacteria

The in vitro activity of telavancin was tested against 743 predominantly antimicrobial-resistant, gram-positive isolates. Telavancin was highly active against methicillin-resistant staphylococci (MIC(90), 0.5 to 1 microg/ml), streptococci (all MICs, < or =0.12 microg/ml), and VanB-type enterococci (all MICs, < or =2 microg/ml). Time-kill studies demonstrated the potent bactericidal activity of telavancin.     

In vitro activities of linezolid against important gram-positive bacterial pathogens including vancomycin-resistant enterococci.

The emergence of resistance in gram-positive bacteria has necessitated a search for new antimicrobial agents. Linezolid is an oxazolidinone, a new class of antibacterial agents with enhanced activity against pathogens. We compared the activity of linezolid to those of other antimicrobial agents against 3,945 clinical isolates. Linezolid demonstrated potent activity against all isolates tested. For all vancomycin-susceptible enterococci, staphylococci, and streptococci, the activity of linezolid was comparable to that of vancomycin. Against oxacillin-resistant staphylococci and vancomycin-resistant enterococci, linezolid was the most active agent tested. In summary, linezolid appears to be a promising new antimicrobial agent for the treatment of gram-positive infections.     

In vitro activity of RP59500, an injectable streptogramin antibiotic, against vancomycin-resistant gram-positive organisms.

The in vitro activity of RP59500, a streptogramin antibiotic, against 146 clinical isolates of vancomycin-resistant gram-positive bacteria was examined. Five strains of the species Enterococcus casseliflavus and Enterococcus gallinarum, for which the MIC of vancomycin was 8 micrograms/ml, were also studied. Twenty-eight vancomycin-susceptible strains of Enterococcus faecalis and Enterococcus faecium were included for comparison. The drug was highly active against Leuconostoc spp., Lactobacillus spp., and Pediococcus spp. (MICs, < or = 2 micrograms/ml). RP59500 was more active against vancomycin-susceptible strains of E. faecium than E. faecalis (MICs for 90% of the strains [MIC90s], 1.0 versus 32 micrograms/ml). Vancomycin-resistant strains of E. faecalis were as resistant to RP59500 as vancomycin-susceptible strains (MIC90, 32 micrograms/ml), but some vancomycin-resistant E. faecium strains were relatively more resistant to the new agent (MIC90, 16; MIC range, 0.5 to 32 micrograms/ml) than were vancomycin-susceptible organisms of this species.     

In vitro activity of linezolid against slowly growing nontuberculous Mycobacteria

MICs of linezolid in broth microdilutions were tested against 341 slowly growing nontuberculous mycobacteria (NTM) belonging to 15 species. The proposed linezolid susceptibility MICs for all Mycobacterium marinum, Mycobacterium szulgai, Mycobacterium kansasii, Mycobacterium malmoense, and Mycobacterium xenopi isolates and for 90% of Mycobacterium gordonae and Mycobacterium triplex isolates were 相似文献   

In vitro activity of linezolid against Staphylococcus aureus: a population study

In our study, we aim to determine the existence of microorganisms that are heteroresistant to linezolid among Staphylococcus aureus clinical isolates in our setting between 1996 and 2002; during this period, linezolid was not used in clinical practice. There was no resistant subpopulation to 4 mg/l of linezolid in 99.4% of the strains. On the other hand, 16.46% of the strains exhibited resistant subpopulations to 4 microg/ml of vancomycin. However, the emergence of strains resistant to this drug has been described and the emergence of resistant strains should be monitored.     

In vitro activity of teichomycin against isolates of gram-positive bacteria

The in vitro activity of teichomycin has been evaluated against 189 clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis and group D streptococci. Teichomycin was as active as vancomycin, a chemically related antibiotic, on staphylococci and inhibited the in vitro growth of methicillin-resistant strains at the same concentration necessary to inhibit the sensitive ones. Against group D streptococci teichomycin was about three times more active than vancomycin (MIC50 = 0.125 mg/l, MIC90 = 0.4 mg/l). MBC:MIC ratios of both drugs against staphylococci were comparable, but teichomycin had higher bactericidal activity against group D streptococci, as shown also by killing curves. The activity of teichomycin was not significantly affected by variation of pH, even if the maximum activity was achieved at neutral pH, or by different methods of MIC evaluation. The antibiotic seemed more active when tested with a low inoculum (10(3)-10(5)/ml): a two- to threefold increase in MIC was observed at an inoculum of 10(7)/ml. A reduction of the in vitro activity could be shown when Penassay broth was used as culture medium.     

In vitro activity of daptomycin versus linezolid and vancomycin against gram-positive uropathogens and ampicillin against enterococci, causing complicated urinary tract infections

OBJECTIVES: The existing therapeutic options for complicated urinary tract infections (UTI) caused by gram-positive uropathogens are not always optimal. Therefore, newer antimicrobials have to be assessed. METHODS: The antimicrobial activity of daptomycin was tested versus linezolid, vancomycin, and ampicillin (enterococci on ly), against pathogens from three different collections: (1) Uropathogens from hospitalized urological patients with complicated and/or hospital-acquired UTIs of the Urologic Clinic, Hospital St. Elisabeth, Straubing. (2) Uropathogens from a multicenter study comprising 37 urological centers throughout Germany. (3) Methicillin-resistant Staphylococcus aureus (MRSA) isolates of patients and staff within the Hospital St. Elisabeth, Straubing. Genotyping of the latter isolates was performed by pulsed-field gel electrophoresis. The minimal inhibitory concentrations (MIC) of daptomycin, linezolid, vancomycin, and ampicillin (only tested against enterococci) were determined by an agar dilution method using a multipointer with an inoculum of 10(4) CFU per point. RESULTS: For all methicillin-susceptible Staphylococcus aureus (n = 25), MRSA (n = 49), methicillin-susceptible coagulase-negative staphylococci (n = 129), methicillin-resistant coagulase-negative staphylococci (n = 33), for Enterococcus faecalis (n = 289), and for Enterococcus faecium (n = 4) the MICs ranged up to 2 mg/l (daptomycin, linezolid), up to 4 mg/l (vancomycin), and up to 8 mg/l (ampicillin, enterococci only) indicating that all strains were susceptible to the antibiotics tested. CONCLUSIONS: According to the in vitro activity daptomycin may be considered a promising antibacterial agent for the treatment of complicated UTI caused by gram-positive uropathogens. Thus, daptomycin should be evaluated in a clinical study.     

In vitro activity and killing effect of uperin 3.6 against gram-positive cocci isolated from immunocompromised patients

The in vitro activity of uperin 3.6, alone or combined with six antibiotics, against gram-positive cocci, including Rhodococcus equi, methicillin-resistant staphylococci, and vancomycin-resistant enterococci, was investigated. All isolates were inhibited at concentrations of 1 to 16 mg/liter. Synergy was demonstrated when uperin 3.6 was combined with clarithromycin and doxycycline.     

In vitro activity of linezolid against multiply resistant Gram-positive clinical isolates

The in vitro activity of the oxazolidinone linezolid was compared with the activities of vancomycin and teicoplanin against 450 Gram-positive clinical isolates, including a variety of multiply resistant strains. Linezolid inhibited all microorganisms tested at < or = 4 mg/L, including methicillin- and teicoplanin-resistant staphylococci, glycopeptide-resistant enterococci, penicillin- and multiply resistant pneumococci and viridans streptococci, and erythromycin-resistant beta-haemolytic streptococci. The MIC(90) of linezolid for all isolates was 2 mg/L.