In vitro activities of norfloxacin and ciprofloxacin against Mycobacterium tuberculosis, M. avium complex, M. chelonei, M. fortuitum, and M. kansasii

The activities of ciprofloxacin and norfloxacin against 100 mycobacteria isolates were studied in vitro by the 1% standard proportion method. Ciprofloxacin was more active against M. tuberculosis and M. fortuitum with MICs of 1.0 and 0.25 microgram/ml, respectively, against 90% of isolates; norfloxacin had MICs of 8.0 and 2.0 micrograms/ml, respectively, against 90% of isolates.     

In vitro activity of ciprofloxacin, levofloxacin, and trovafloxacin, alone and in combination with beta-lactams, against clinical isolates of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Burkholderia cepacia

We tested three fluoroquinolones (ciprofloxacin, levofloxacin, and trovafloxacin), each combined with each of four beta-lactams (cefoperazone, ceftriaxone, imipenem, and meropenem) for synergy against clinical isolates of nosocomial strains of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Burkholderia cepacia. The ciprofloxacin-beta-lactam combinations showed synergy against none or only a small fraction (7 to 10%) of the P. aeruginosa and B. cepacia isolates. Ciprofloxacin-cefoperazone, -ceftriaxone, and -meropenem were synergic against 50%, 25%, and 30% of the S. maltophilia isolates, respectively. Among the levofloxacin combinations, only those with cefoperazone and imipenem showed significant synergy, and this only against B. cepacia (50% and 30%, respectively). Trovafloxacin-cefoperazone and -imipenem showed modest synergy against P. aeruginosa (23% and 27%, respectively), as did trovafloxacin-cefoperazone and -ceftriaxone against B. cepacia (30%). The trovafloxacin-imipenem combination was synergic against all isolates of B. cepacia. Because of their synergy, the following combinations may be useful in the nosocomial setting: trovafloxacin-cefoperazone or -imipenem against P. aeruginosa; ciprofloxacin-cefoperazone, -ceftriaxone, or -meropenem against S. maltophilia; levofloxacin-cefoperazone and trovafloxacin-imipenem against B. cepacia.     

Activity of doripenem with and without levofloxacin,amikacin, and colistin against Pseudomonas aeruginosa and Acinetobacter baumannii

At 24 h, sub-MIC doripenem and levofloxacin showed synergy against 21 of 25 Pseudomonas aeruginosa strains, sub-MIC doripenem and amikacin against 22 isolates, and sub-MIC doripenem and colistin against 19 isolates. Of 25 Acinetobacter baumannii strains, sub-MIC doripenem and levofloxacin showed synergy against 11 strains at 24 h, sub-MIC doripenem and amikacin against 24 strains, and sub-MIC doripenem and colistin against all isolates.     

Activities of a new fluoroketolide, HMR 3787, and its (des)-fluor derivative RU 64399 compared to those of telithromycin, erythromycin A, azithromycin, clarithromycin, and clindamycin against macrolide-susceptible or -resistant Streptococcus pneumoniae and S. pyogenes

Activities of HMR 3787 and RU 64399 were compared to those of three macrolides, telithromycin, and clindamycin against 175 Streptococcus pneumoniae isolates and 121 Streptococcus pyogenes isolates. HMR3787 and telithromycin were the most active compounds tested against pneumococci. Telithromycin and RU 64399 were equally active against macrolide-susceptible (MICs, 0.008 to 0.06 microg/ml) and -resistant S. pyogenes isolates, but HMR 3787 had lower MICs for ermB strains.     

Comparative Activity of Tobramycin, Amikacin, and Gentamicin Alone and with Carbenicillin Against Pseudomonas aeruginosa

The effect of gentamicin against 130 clinical isolates of Pseudomonas aeruginosa was compared with that of two investigational aminoglycoside antibiotics, tobramycin and amikacin. Minimal inhibitory concentration data indicated that, on a weight basis, tobramycin was two to four times as active as gentamicin against most isolates. However, 14 of 18 organisms highly resistant to gentamicin (>/=80 mug/ml) were also highly resistant to tobramycin. Amikacin was the least active aminoglycoside on a weight basis, but none of the isolates were highly resistant to this antibiotic. When therapeutically achievable concentrations were used, adding carbenicillin to gentamicin or to tobramycin enhanced inhibitory activity against those isolates susceptible (相似文献   

Comparative in vitro activities of azithromycin, Bay y 3118, levofloxacin, sparfloxacin, and 11 other oral antimicrobial agents against 194 aerobic and anaerobic bite wound isolates.

The activities of sparfloxacin, levofloxacin, Bay y 3118, azithromycin, cefprozil, loracarbef, and nine other oral antimicrobial agents against 194 aerobic and anaerobic clinical bite wound isolates were determined by the agar dilution method. Sparfloxacin, levofloxacin, and Bay y 3118 were active against all aerobic isolates (MICs at which 90% of the isolates are inhibited [MIC90], < or = 1.0 microgram/ml for sparfloxacin and levofloxacin and 0.1 microgram/ml for Bay y 3118) and many anaerobic isolates, with the exception of the fusobacteria. Azithromycin was more active than erythromycin by 1 to 2 dilutions against many aerobes, including Pasteurella multocida and Eikenella corrodens, and by 2 to 4 dilutions against anaerobic isolates. Cefprozil was more active (MIC90, < or = 1 microgram/ml) than loracarbef (MIC90, < or = 4 micrograms/ml) against aerobic gram-positive isolates, but both had poor activity (MIC90, > or = 16 micrograms/ml) against peptostreptococci. Both cefprozil and loracarbef had MIC90s of < or = 0.5 micrograms/ml against P. multocida.     

Rates and Extents of Antifungal Activities of Amphotericin B, Flucytosine, Fluconazole, and Voriconazole against Candida lusitaniae Determined by Microdilution, Etest, and Time-Kill Methods

Amphotericin B, flucytosine, fluconazole, and voriconazole alone and in combination were evaluated against isolates of Candida lusitaniae. MICs were determined by broth microdilution and Etest, and time-kill studies were conducted. Amphotericin B resulted in fungicidal activity against most isolates, whereas fluconazole, voriconazole, and flucytosine produced primarily fungistatic activities. The addition of flucytosine to amphotericin B resulted in a faster rate and greater extent of kill for isolates for which the MICs of amphotericin B were elevated.     

In vitro activities of ketolide HMR3647, macrolides, and other antibiotics against Lactobacillus, Leuconostoc, and Pediococcus isolates

Testing of susceptibility to 13 antibiotics was performed with 90 isolates of Lactobacillus, Leuconostoc, and Pediococcus. MICs at which 90% of the isolates tested were inhibited by HMR3647, erythromycin, and ciprofloxacin were 0.015, 0.125 and 32 microg/ml, respectively. The penicillin MIC was > or = 16 microg/ml against 26.2% of the studied Lactobacillus sp. isolates and 50% of Lactobacillus plantarum. HMR3647 showed excellent activity against these genera.     

In vitro activities of posaconazole, fluconazole, itraconazole, voriconazole, and amphotericin B against a large collection of clinically important molds and yeasts

The in vitro activity of the novel triazole antifungal agent posaconazole (Noxafil; SCH 56592) was assessed in 45 laboratories against approximately 19,000 clinically important strains of yeasts and molds. The activity of posaconazole was compared with those of itraconazole, fluconazole, voriconazole, and amphotericin B against subsets of the isolates. Strains were tested utilizing Clinical and Laboratory Standards Institute broth microdilution methods using RPMI 1640 medium (except for amphotericin B, which was frequently tested in antibiotic medium 3). MICs were determined at the recommended endpoints and time intervals. Against all fungi in the database (22,850 MICs), the MIC(50) and MIC(90) values for posaconazole were 0.063 microg/ml and 1 mug/ml, respectively. MIC(90) values against all yeasts (18,351 MICs) and molds (4,499 MICs) were both 1 mug/ml. In comparative studies against subsets of the isolates, posaconazole was more active than, or within 1 dilution of, the comparator drugs itraconazole, fluconazole, voriconazole, and amphotericin B against approximately 7,000 isolates of Candida and Cryptococcus spp. Against all molds (1,702 MICs, including 1,423 MICs for Aspergillus isolates), posaconazole was more active than or equal to the comparator drugs in almost every category. Posaconazole was active against isolates of Candida and Aspergillus spp. that exhibit resistance to fluconazole, voriconazole, and amphotericin B and was much more active than the other triazoles against zygomycetes. Posaconazole exhibited potent antifungal activity against a wide variety of clinically important fungal pathogens and was frequently more active than other azoles and amphotericin B.     

头孢米诺等抗菌药物对大肠埃希菌、肺炎克雷伯菌及拟杆菌属的体外抗菌活性

目的 比较头孢米诺等抗菌药物对临床分离大肠埃希菌、肺炎克雷伯菌、拟杆菌属的体外抗菌活性.方法 琼脂稀释法测定16种抗菌药物对来自全国15家教学医院的945株大肠埃希菌和588株肺炎克雷伯菌的MIC值以及4种抗菌药物对50株拟杆菌属的MIC值.WHONET 5.4软件进行药敏数据统计分析.结果 1 533株大肠埃希菌和肺炎克雷伯菌中,不产超广谱β内酰胺酶(extended spectrum beta lactamases,ESBLs)和AmpC 628株,837株仅产ESBLs,68株产AmpC.头孢米诺对不产ESBLs或单产ESBLs的大肠埃希菌和肺炎克雷伯菌敏感率均高于90%,其MIC50较头孢美唑低2～4倍,较头孢西丁低8～16倍;MIC90较头孢美唑低2～8倍,较头孢西丁低8～16倍.对单产ESBLs的菌株,头孢米诺体外抗菌活性优于第三、四代头孢菌素、头孢哌酮/舒巴坦、氨曲南、左氧氟沙星和阿米卡星,劣于碳青霉烯类药物,活性与哌拉丙林/三唑巴坦相仿.但对产AmpC的菌株,头孢米诺的敏感率低于20%.头孢米诺对拟杆菌属的敏感率为90%,高于头孢美唑(50%～70%)和青霉素(0%),活性与甲硝唑相仿.结论 头孢米诺对产ESBLs及非产ESBLs的大肠埃希菌和肺炎克雷伯菌以及拟杆菌属有良好的体外抗菌活性,提示头孢米诺可为临床治疗此类菌株感染提供一种选择.     

头孢米诺等抗菌药物对大肠埃希菌、肺炎克雷伯菌及拟杆菌属的体外抗菌活性

目的 比较头孢米诺等抗菌药物对临床分离大肠埃希菌、肺炎克雷伯菌、拟杆菌属的体外抗菌活性.方法 琼脂稀释法测定16种抗菌药物对来自全国15家教学医院的945株大肠埃希菌和588株肺炎克雷伯菌的MIC值以及4种抗菌药物对50株拟杆菌属的MIC值.WHONET 5.4软件进行药敏数据统计分析.结果 1 533株大肠埃希菌和肺炎克雷伯菌中,不产超广谱β内酰胺酶(extended spectrum beta lactamases,ESBLs)和AmpC 628株,837株仅产ESBLs,68株产AmpC.头孢米诺对不产ESBLs或单产ESBLs的大肠埃希菌和肺炎克雷伯菌敏感率均高于90%,其MIC_(50)较头孢美唑低2～4倍,较头孢西丁低8～16倍;MIC90较头孢美唑低2～8倍,较头孢西丁低8～16倍.对单产ESBLs的菌株,头孢米诺体外抗菌活性优于第三、四代头孢菌素、头孢哌酮/舒巴坦、氨曲南、左氧氟沙星和阿米卡星,劣于碳青霉烯类药物,活性与哌拉丙林/三唑巴坦相仿.但对产AmpC的菌株,头孢米诺的敏感率低于20%.头孢米诺对拟杆菌属的敏感率为90%,高于头孢美唑(50%～70%)和青霉素(0%),活性与甲硝唑相仿.结论 头孢米诺对产ESBLs及非产ESBLs的大肠埃希菌和肺炎克雷伯菌以及拟杆菌属有良好的体外抗菌活性,提示头孢米诺可为临床治疗此类菌株感染提供一种选择.     

Comparative in vitro activities of ciprofloxacin, gemifloxacin, grepafloxacin, moxifloxacin, ofloxacin, sparfloxacin, trovafloxacin, and other antimicrobial agents against bloodstream isolates of gram-positive cocci

The in vitro activity of gemifloxacin against 316 bloodstream isolates of staphylococci, pneumococci, and enterococci was compared with the activities of six fluoroquinolones and three other antimicrobial agents. Of the antimicrobial agents tested, gemifloxacin was the most potent against penicillin-intermediate and -resistant pneumococci, methicillin-susceptible and -resistant Staphylococcus epidermidis isolates, and coagulase-negative staphylococci.     

Susceptibility of Neisseria gonorrhoeae associated with pelvic inflammatory disease to cefoxitin, ceftriaxone, clindamycin, gentamicin, doxycycline, azithromycin, and other antimicrobial agents.

We determined the susceptibilities, by the agar dilution method, of 84 recent clinical isolates of Neisseria gonorrhoeae obtained from women with pelvic inflammatory disease in the United States to the following antimicrobial agents: penicillin, cefoxitin, cefotetan, ceftriaxone, ceftizoxime, cefixime, tetracycline, doxycycline, ciprofloxacin, ofloxacin, erythromycin, azithromycin, clindamycin, and gentamicin. Twenty-five percent of the isolates were resistant to penicillin and 20% were resistant to tetracycline. In comparison, doxycycline was more active than tetracycline and azithromycin was more active than erythromycin in vitro. Ceftriaxone, ceftizoxime, and cefixime were equally active against penicillin-susceptible isolates, but they had different in vitro activities against gonococcal isolates possessing chromosomally mediated resistance to penicillin. Overall, cefoxitin was slightly more active than cefotetan and ciprofloxacin was more active in vitro than ofloxacin, especially against N. gonorrhoeae with chromosomally mediated resistance. Criteria for the interpretation of susceptibility data for N. gonorrhoeae are not available for clindamycin or gentamicin, but for at least half of all isolates, including penicillin-susceptible isolates, at least 4 micrograms of clindamycin or gentamicin per ml was required to inhibit growth in vitro.     

In Vitro Activities of Linezolid, Meropenem, and Quinupristin-Dalfopristin against Group C and G Streptococci, Including Vancomycin-Tolerant Isolates

The in vitro activities of meropenem, linezolid, quinupristin-dalfopristin, vancomycin, and penicillin against 130 clinical isolates of group C and G streptococci, including vancomycin-tolerant isolates, were evaluated. Meropenem, linezolid, quinupristin-dalfopristin, vancomycin, and penicillin MICs at which 90% of the isolates were inhibited were 0.06, 2.0, 0.25, 0.5, and < or = 0.016 microg/ml, respectively. Meropenem, linezolid, quinupristin-dalfopristin, and penicillin were active against group C and G streptococci, including vancomycin-resistant strains.     

Combined activity of sulfamethoxazole, trimethoprim, and polymyxin B against gram-negative bacilli

The activity of the three two-drug combinations of sulfamethoxazole (SMX), trimethoprim (TMP), and polymyxin B (PB) against 52 clinical isolates of gram-negative bacilli was studied by a "checkerboard" agar dilution method. The organisms studied included strains of Enterobacter spp., Klebsiella pneumoniae, Serratia marcescens, Providence, Proteus, and Pseudomonas aeruginosa. The majority of these isolates were resistant to at least two of the three agents used in the combined studies and to the most commonly used antimicrobials. The TMP-PB combination demonstrated enhanced activity more frequently than the other two-drug combinations, showing synergism or addition in 85% of the combined studies; indifference or antagonism was also observed least frequently with TMP-PB. The great majority (83%) of Enterobacter-Klebsiella-Serratia isolates were susceptible to enhanced activity of all combinations. Proteus-Providence isolates were frequently susceptible (63%), but combined activity was indifferent or antagonistic against 60% of P. aeruginosa. Twelve isolates were selected for "killing-curve" assays in which an inoculum was incubated with SMX, TMP, and PB individually and in various two- and three-drug combinations. Surviving bacteria were counted at timed intervals over 24 h of incubation. The triple combination (SMX-TMP-PB) was synergistic against 9 of 12 isolates, whereas TMP-PB and SMX-PB showed synergism against 5 and 3 isolates, respectively. These data suggest that, although TMP-PB will often show enhanced activity against the gram-negative bacilli studied here, optimal antibacterial activity will be demonstrated when the three-drug combination is used.     

Susceptibility of Acinetobacter calcoaceticus to antimicrobial drugs, alone and combined, with and without defibrinated human blood

Twenty-five clinical isolates of Acinetobacter calcoaceticus were examined for susceptibility to 14 antimicrobial drugs. In terms of inhibitory and bactericidal activities, imipenem and polymyxin B were most active, followed by amikacin and ceftazidime. Four isolates were resistant against fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin). The isolates varied in susceptibility to aztreonam, cefotaxime, cotrimoxazole, gentamicin, mezlocillin, netilmicin and piperacillin. Fresh defibrinated human blood from 3 donors revealed similar killing kinetics against 8 selected isolates. In time-kill curve experiments, human blood enhanced the activity of amikacin more than that of ceftazidime, ciprofloxacin and imipenem against A. calcoaceticus. The combinations of amikacin + imipenem and amikacin + ceftazidime in the presence of human blood were effective against this microorganism. Human blood combined with ciprofloxacin + imipenem was more effective than blood with added ceftazidime + ciprofloxacin.     

In vitro activity of nitazoxanide and related compounds against isolates of Giardia intestinalis, Entamoeba histolytica and Trichomonas vaginalis.

The activities of the N-(nitrothiazolyl) salicylamide nitazoxanide and its metabolite tizoxanide were compared with metronidazole in vitro in microplates against six axenic isolates of Giardia intestinalis. Tizoxanide was eight times more active than metronidazole against metronidazole-susceptible isolates and twice as active against a resistant isolate. In 10 axenic isolates of Entamoeba histolytica, while tizoxanide was almost twice as active as metronidazole against more susceptible isolates, it was more than twice as active against less susceptible isolates. Fourteen metronidazole-susceptible isolates of Trichomonas vaginalis were 1.5 times more susceptible to tizoxanide, which was nearly five times as active against resistant isolates. Two highly metronidazole-resistant isolates retained complete susceptibility to tizoxanide, and one moderately resistant isolate showed reduced susceptibility. In all three organisms, nitazoxanide results paralleled those of tizoxanide. Analogues lacking the reducible nitro-group had similar low activities against susceptible G. intestinalis, E. histolytica and T. vaginalis, indicating that nitro-reduction and free radical production was a probable mode of action. Nitazoxanide and its metabolite tizoxanide are more active in vitro than metronidazole against G. intestinalis, E. histolytica and T. vaginalis. Although, like metronidazole, they depend on the presence of a nitro-group for activity, they retain some activity against metronidazole-resistant strains, particularly of T. vaginalis. The results suggest that resistance mechanisms for metronidazole can be bypassed by nitazoxanide and tizoxanide.     

In Vitro Activity of LY333328 Against Vancomycin-Resistant Enterococci,Methicillin-Resistant Staphylococcus aureus,and Penicillin-Resistant Streptococcus pneumoniae

We report the activity of LY333328 against 35 clinical isolates of vancomycin-resistant enterococci (including organisms carrying the vanA, vanB, vanC-1, and vanC-2/3 genes, as determined by PCR), 33 clinical isolates of methicillin-resistant S. aureus, and 29 clinical isolates of high-level penicillin-resistant S. pneumoniae. All isolates of vancomycin-resistant enterococci were inhibited by 2 μg/mL LY333328, and 8 μg/mL LY333328 was bactericidal against all isolates tested. All isolates of methicillin-resistant S. aureus were inhibited by 1 μg/mL LY333328, and 4 μg/mL LY333328 was bactericidal against all methicillin-resistant S. aureus isolates tested. All isolates of penicillin-resistant S. pneumoniae were inhibited by <0.125 μg/mL LY333328, and 0.25 μg/mL LY333328 was bactericidal against all S. pneumoniae isolates tested. LY333328 is a promising new glycopeptide antimicrobial agent.     

In-vitro activity of pefloxacin compared to enoxacin, norfloxacin, gentamicin and new beta-lactams

The in-vitro activity of pefloxacin was compared with that of norfloxacin, enoxacin, nalidixic acid, gentamicin, cefotaxime, ceftazidime and, where appropriate, other beta-lactams against a total of 363 recent clinical isolates. An agar dilution procedure was used to determine MICs and two inocula (10(4) and 10(6) cfu) were used throughout. Pefloxacin inhibited 90% of isolates of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, indole-positive Proteus spp., Enterobacter spp., Shigella sonnei, Salmonella typhi, Campylobacter jejuni, Staphylococcus aureus and Haemophilus influenzae at less than or equal to 0.5 mg/l. Serratia marcescens and Providencia stuartii were somewhat more resistant, 2 mg/l of pefloxacin being required to inhibit 90% of isolates of these species. Pefloxacin inhibited 90% of isolates of Pseudomonas aeruginosa at 4 mg/l and 90% of isolates of the Bacteroides fragilis group at 16 mg/l. The activity of enoxacin was similar to that of pefloxacin, with enoxacin being four-fold less active against Staph. aureus, two-fold less active against the Bacteroides fragilis group and most species of the Enterobacteriaceae, and two-fold more active against Ps. aeruginosa. Pefloxacin showed good activity against gentamicin-resistant Ps. aeruginosa and Enterobacteriaceae and against methicillin-resistant Staph. aureus. Strains with decreased susceptibility to norfloxacin tended to be less susceptible to both pefloxacin and enoxacin.     

Interactions of ciprofloxacin with clindamycin, metronidazole, cefoxitin, cefotaxime, and mezlocillin against gram-positive and gram-negative anaerobic bacteria.

A total of 598 clinical isolates of anaerobic bacteria were tested against ciprofloxacin by the agar dilution technique with 10(5) CFU on Wilkins-Chalgren medium. Selected strains representative of the six major genera of anaerobes relatively resistant to the quinolones were tested for interactions with ciprofloxacin in combination with clindamycin, metronidazole, cefoxitin, cefotaxime, or mezlocillin by using a checkerboard agar dilution technique. Cefotaxime-ciprofloxacin and clindamycin-ciprofloxacin were the most effective combinations, with 16% of all isolates and 44% of the Bacteroides fragilis group isolates responding synergistically to the former combination and 9% of all isolates and 37% of Peptostreptococcus isolates responding synergistically to the latter. Occasional synergy was seen with all other antibiotic combinations except for metronidazole-ciprofloxacin. Likewise, synergism was seen with all groups of anaerobes except for Fusobacterium species. Antagonistic interactions were observed only with a Peptostreptococcus intermedius strain tested against clindamycin-ciprofloxacin. These data suggest that combinations of ciprofloxacin with these agents may be useful for certain resistant anaerobic infections.