Quality control parameters for susceptibility tests of Haemophilus influenzae against three carbapenems.
Explore the source record for details and available documents.
Carbapenems↗
Biomedical subjects
A L Barry
Publications and source records attributed to A L Barry.
Bactericidal activity of quinupristin-dalfopristin against Staphylococcus aureus: clindamycin susceptibility as a surrogate indicator.
Of 516 Staphylococcus aureus strains tested, 97.1% were susceptible to quinupristin-dalfopristin, which was bactericidal for 22 (56%) of the 39 strains tested, comparable to vancomycin. All 17 clindamycin and macrolide-resistant strains were inhibited but not killed by quinupristin-dalfopristin, whereas all 22 clindamycin-susceptible strains (5 were macrolide resistant) were killed.
Anti-Bacterial Agents↗
Rapid automated antimicrobial susceptibility testing of Streptococcus pneumoniae by use of the bioMerieux VITEK 2.
The VITEK 2 is a new automated instrument for rapid organism identification and susceptibility testing. It has the capability of performing rapid susceptibility testing of Streptococcus pneumoniae with specially configured cards that contain enriched growth medium and antimicrobial agents relevant for this organism. The present study compared the results of testing of a group of 53 challenge strains of pneumococci with known resistance properties and a collection of clinical isolates examined in two study phases with a total of 402 and 416 isolates, respectively, with a prototype of the VITEK 2. Testing was conducted in three geographically separate laboratories; the challenge collection was tested by all three laboratories, and the unique clinical isolates were tested separately by the individual laboratories. The VITEK 2 results of tests with 10 antimicrobial agents were compared to the results generated by the National Committee for Clinical Laboratory Standards reference broth microdilution MIC test method. Excellent interlaboratory agreement was observed with the challenge strains. The overall agreement within a single twofold dilution of MICs defined by the VITEK 2 and reference method with the clinical isolates was 96.3%, although there were a number of off-scale MICs that could not be compared. The best agreement with the clinical isolates was achieved with ofloxacin and chloramphenicol (100%), and the lowest level of agreement among those drugs with sufficient on-scale MICs occurred with trimethoprim-sulfamethoxazole (89.7%). Overall there were 1.3% very major, 6.6% minor, and no major interpretive category errors encountered with the clinical isolates, although >80% of the minor interpretive errors involved only a single log(2) dilution difference. The mean time for generation of susceptibility results with the clinical isolates was 8.1 h. The VITEK 2 provided rapid, reliable susceptibility category determinations with both the challenge and clinical isolates examined in this study.
Anti-Bacterial Agents↗
Quality control limits for broth microdilution susceptibility tests of ten antifungal agents.
Broth microdilution susceptibility tests of Candida species have now been standardized by the National Committee for Clinical Laboratory Standards (NCCLS). An eight-laboratory collaborative study was carried out in order to document reproducibility of tests of Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258 by the NCCLS method. Replicate broth microdilution tests were used to define control limits for 24- and 48-h MICs of amphotericin B, flucytosine, fluconazole, voriconazole, ketoconazole, itraconazole, caspofungin (MK 0991), ravuconazole (BMS 207147), posaconazole (SCH 56592), and LY 303366.
Antifungal Agents↗
Antimicrobial resistance among clinical isolates of Streptococcus pneumoniae in North America.
From a historical perspective, the development of antibiotic resistance among Streptococcus pneumoniae isolates can be traced over the past 3 decades. In North America, penicillin-resistant pneumococci are now found in nearly all medical centers, but the prevalence of such strains varies by region and time period. In the United States, only approximately 75% of all pneumococci are fully susceptible to penicillin, 15% are intermediately susceptible, and approximately 10% are highly resistant. The latter are often multiply resistant to other unrelated drugs, which leaves few effective chemotherapeutic agents with which to treat serious infections caused by such strains. New approaches to therapy are needed to avoid further selection of antibiotic-resistant mutants; these include discontinuing inappropriate or unnecessary use of antibiotics.
Anti-Bacterial Agents↗
Antibacterial activity of moxifloxacin (Bay 12-8039) against aerobic clinical isolates, and provisional criteria for disk susceptibility tests.
Moxifloxacin (Bay 12-8039), ciprofloxacin, and levofloxacin were compared in vitro against 1074 clinical isolates gathered from different medical centers throughout North America during the winter months of 1997. Moxifloxacin E tests and broth microdilution tests gave comparable results. Moxifloxacin was particularly potent against respiratory pathogens such as Haemophilus influenzae and Streptococcus pneumoniae. Ciprofloxacin was the most potent study drug against the family of Enterobacteriaceae and Pseudomonas spp. For tests of 5 microg moxifloxacin disks, zone size criteria of < or = 17 mm for resistant (MIC > or = 8 microg/ml) and > or = 21 mm for susceptible (MIC < or = 2 microg/ml) are provisionally proposed for use while clinical trials are under way.
Anti-Infective Agents↗
Lack of effect of antibiotic resistance on susceptibility of microorganisms to chlorhexidine gluconate or povidone iodine.
Explore the source record for details and available documents.
Anti-Bacterial Agents↗
In vitro activity of trovafloxacin against ciprofloxacin-susceptible and -resistant clinical bacterial isolates and assessment of the trovafloxacin disk test.
A total of 4241 consecutive clinical bacterial isolates from 10 North American medical centers were tested for susceptibility to trovafloxacin. Trovafloxacin was significantly more active than ciprofloxacin against Gram-positive bacteria, Acinetobacter spp., and Stenotrophomonas maltophilia, and resistance to trovafloxacin occurred in these groups only among isolates with high-level resistance (MIC > or = 16 micrograms/mL) to ciprofloxacin. With other species, the two drugs had comparable activity. Concerns about staphylococci and Pseudomonas aeruginosa with trovafloxacin MICs of 2.0 micrograms/mL (the upper end of the susceptible category) are discussed. Results of trovafloxacin disk diffusion test on more than 3200 nonfastidious isolates supported the FDA-approved zone size interpretive criteria when the MIC breakpoint of < or = 2.0 micrograms/mL is used to define the trovafloxacin-susceptible category.
Anti-Infective Agents↗
Fosfomycin tromethamine susceptibility of outpatient urine isolates of Escherichia coli and Enterococcus faecalis from ten North American medical centres by three methods.
One hundred percent of 1097 Escherichia coli and 97.5% of 157 Enterococcus faecalis isolates from outpatient urine specimens at ten North American medical centres were susceptible to fosfomycin tromethamine. The Etest MICs correlated well with those of agar dilution. Disc diffusion zone diameters correlated well with MICs and supported the previously proposed zone diameter breakpoints for fosfomycin.
Anti-Bacterial Agents↗
Fluoroquinolone resistance among recent clinical isolates of Streptococcus pneumoniae.
Explore the source record for details and available documents.
Anti-Infective Agents↗
In-vitro antimicrobial activity of a carbapenem, MK-0826 (L-749,345) and provisional interpretive criteria for disc tests.
The in-vitro activity of MK-0826, a new oral carbapenem, was compared with that of imipenem by broth microdilution susceptibility tests against 545 bacterial isolates. MK-0826 had significantly greater activity against Enterobacteriaceae and poorer activity against Pseudomonas aeruginosa and many gram-positive species. MK-0826 disc diffusion tests were also performed according to the NCCLS procedure and tentative interpretive criteria were determined for possible susceptible MIC breakpoints of < or = 4.0 and < or = 2.0 mg/L.
Bacteria, Aerobic↗
In vitro activities of SCH27899 alone and in combination with 17 other antimicrobial agents.
SCH27899, an everninomicin antibiotic, was tested for its in vitro activity against 718 bacterial isolates representing 27 species. The Enterobacteriaceae and nonenteric gram-negative bacilli were resistant to > or = 8.0 microg/ml, but all others were inhibited by < or = 1.0 microg/ml. When tested in combination with 17 other antimicrobial agents against 110 strains, SCH27899 demonstrated no significant antagonism or synergy. Consequently, combination therapy is not contraindicated.
Aminoglycosides↗
Multicenter survey of the in vitro activity of four expanded-spectrum beta-lactams against consecutive contemporary clinical isolates.
A survey of the in vitro susceptibility of consecutive clinical bacterial isolates to cefotaxime, ceftazidime, cefpodoxime, and aztreonam was conducted at 10 North American medical centers during the first quarter of 1997. All four drugs had good activity against Enterobacteriaceae and fastidious Gram-negative bacteria and poor activity against enterococci and methicillin-resistant staphylococci. No significant trends in susceptibility to cefotaxime or ceftazidime were observed when compared with a previous similar survey. The use of cefpodoxime MIC > 2.0 micrograms/mL as a marker for extended-spectrum beta-lactamase production by Escherichia coli and Klebsiella spp. had good sensitivity, but the specificity was very poor for E. coli. Thus, at least for E. coli, this screening test seems to be of questionable value unless used to indicate the need for additional tests such as clavulanic acid inhibition. Disk diffusion zone diameters correlated well with the MICs for all four drugs and support the current interpretive criteria.
Anti-Bacterial Agents↗
Susceptibility to RPR 106,972, quinupristin/dalfopristin and erythromycin among recent clinical isolates of enterococci, staphylococci and streptococci from North American medical centres.
An orally administered streptogramin (RPR 106,972) and a parenteral streptogramin (quinupristin/dalfopristin) were evaluated against a collection of 2481 recent clinical isolates of gram-positive cocci. The isolates were gathered from ten North American medical centres during the winter months of 1996-1997. In spite of minor differences, both streptogramins had essentially identical spectra of activity which included many erythromycin-resistant isolates. Previously proposed interpretative criteria for quinupristin/dalfopristin disc diffusion susceptibility tests were confirmed.
Academic Medical Centers↗
PMX-622 (polymyxin B-dextran 70) does not alter in vitro activities of 11 antimicrobial agents.
Because of its capacity to neutralize the lethality of gram-negative bacterial endotoxic lipopolysaccharides, PMX-622 (polymyxin B bound to dextran 70) is being developed for possible adjunctive therapy of gram-negative sepsis. In this study, it was determined that the in vitro antimicrobial activity of PMX-622 was minimal and that it does not interfere with the in vitro antimicrobial activity of 11 antibiotics commonly used to treat gram-negative infections.
Anti-Bacterial Agents↗
Antipneumococcal activities of a ketolide (HMR 3647), a streptogramin (quinupristin-dalfopristin), a macrolide (erythromycin), and a lincosamide (clindamycin).
Four different compounds belonging to the macrolide-lincosamide-streptogramin B (MLSb) class of antimicrobial agents were tested against 611 Streptococcus pneumoniae strains. The ketolide (HMR 3647, previously RU66647) and the streptogramin (quinupristin-dalfopristin) were both active against pneumococci with high-level MLSb resistance (clindamycin-resistant strains) as well as those with low-level macrolide resistance (clindamycin-susceptible strains).
Anti-Bacterial Agents↗
In vitro antimicrobial activity of MSI-78, a magainin analog.
MSI-78 is a cationic peptide with broad-spectrum antimicrobial activity and is being developed as a topical agent. We compared the in vitro activity of MSI-78 with those of ofloxacin and other antibiotics against fresh clinical isolates. Based on MIC distribution statistics, strains for which the MSI-78 MIC was < or = 64 micro/ml were assumed to be susceptible for purposes of this report. Of 411 aerobic isolates tested, 91% were susceptible to MSI-78, compared to 91% for ofloxacin and 92% for ciprofloxacin. Only enterococci consistently required > or = 64 microg of MSI-78/ml for inhibition. MSI-78 demonstrated bactericidal activity equivalent to that of ofloxacin. Of 61 anaerobes, 97% were susceptible to MSI-78. Of 10 isolates of Candida albicans, 3 were inhibited by MSI-78 at 24 h. Further studies of this compound appear to be warranted.
Anti-Infective Agents↗
In vitro activities of clinafloxacin against contemporary clinical bacterial isolates from 10 North American centers.
Clinafloxacin was more active than ciprofloxacin against 4,213 aerobic and facultative anaerobic bacterial isolates from 10 medical centers, as tested by broth microdilution and disk diffusion methods. The percentage of 201 anaerobes susceptible to clinafloxacin by broth microdilution was comparable to cefoxitin. Our data support the proposed disk diffusion interpretive criteria for aerobic bacteria with 5-microg clinafloxacin disks.
Anti-Infective Agents↗