In vitro activity of CP-99,219, a new fluoroquinolone, against clinical isolates of gram-positive bacteria.

The in vitro activity of the fluoroquinolone CP-99,219 against gram-positive bacteria was compared with those of five other antimicrobial agents. Against ciprofloxacin-susceptible staphylococci and against streptococci, MICs were < or = 0.12 and < or = 0.5 microgram/ml, respectively. CP-99,219 was also more active than ciprofloxacin against ciprofloxacin-resistant staphylococci, most enterococci, Leuconostoc spp., and lactobacilli.

Comparison of Enterococcus raffinosus with Enterococcus avium on the basis of penicillin susceptibility, penicillin-binding protein analysis, and high-level aminoglycoside resistance.

We reidentified our laboratories' collections of 57 enterococcal isolates previously classified as Enterococcus avium by the API Rapid Strep identification system (Analytab Products, Plainview, N.Y.) with the identification criteria recommended by Facklam and Collins (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27: 731-734, 1989). Thirty isolates were identified as true E. avium, 25 isolates were identified as E. raffinosus, and 2 isolates were identified as E. pseudoavium. E. raffinosus could be differentiated from E. avium on the basis of penicillin susceptibility, as follows: MIC for 50% of E. raffinosus isolates tested (MIC50), 32 micrograms/ml; MIC90, 64 micrograms/ml (range, 4 to 64 micrograms/ml); E. avium MIC50, 1 microgram/ml; MIC90, 2 micrograms/ml (range, 0.5 to 2 micrograms/ml). No strains produced detectable beta-lactamase. Penicillin-binding protein (PBP) analysis of all E. raffinosus isolates demonstrated the unique pattern reported previously (M. D. Collins, R. R. Facklam, J. A. E. Farrow, and R. Williamson, FEMS Microbiol. Lett. 57:283-288, 1989); however, a number of newly identified PBPs were noted. Of 25 isolates, 13 had an additional PBP of 77 kDa (designated PBP 6*), while all isolates possessed a 52-kDa PBP (PBP 7) and a 46-kDa PBP (PBP 8). The presence or absence of PBP 6* did not correlate with penicillin susceptibility; however, PBP 7 demonstrated many features suggestive of low penicillin-binding affinity and may represent a possible mechanism for the relative resistance of this species to penicillin, although this hypothesis remains speculative since attempts to develop a penicillin-hypersusceptible E. raffinosus mutant were unsuccessful. E. raffinosus isolates were significantly more likely to exhibit high-level resistance to kanamycin than E. avium strains were (P < 0.001; chi-square); however, no strains demonstrated high-level resistance to gentamicin. No trend toward increasing penicillin resistance was noted among this collection of E. avium and E. raffinosus isolates collected over the past 35 and 14 years, respectively. Relative resistance to penicillin may be a helpful differentiating feature between E. avium and E. raffinosus when assessment of raffinose metabolism is not possible or is indeterminant.

Efficacy of different beta-lactams against an extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strain in the rat intra-abdominal abscess model.

Although standard-inoculum MICs were within the susceptible range for all compounds, cefoperazone, cefotaxime, and cefpirome were significantly less effective than imipenem or the combination of cefoperazone and sulbactam in the treatment of rat intra-abdominal abscesses due to an extended-spectrum beta-lactamase-producing strain of Klebsiella pneumoniae.

In vitro activity of BAY v 3522, a new cephalosporin for oral administration.

The activity of BAY v 3522 was tested against over 500 clinical bacterial isolates and compared with the activities of ampicillin, amoxicillin-clavulanate, cefaclor, cefixime, cefuroxime, cephalexin, and/or ciprofloxacin, erythromycin, and metronidazole. BAY v 3522 activity against staphylococci and streptococci equaled or exceeded those of the other agents. BAY v 3522 exhibited no significant advantage over cefaclor, cefuroxime, or cephalexin against gram-negative bacilli.

In vitro activity of sparfloxacin (AT-4140, CI-978, PD 131501), a new quinolone antimicrobial agent.

In vitro activity of sparfloxacin (AT-4140, CI-978, PD 131501) against clinical bacterial isolates was compared with those of ciprofloxacin and vancomycin or imipenem. Sparfloxacin was more active or equal to ciprofloxacin against most Gram-positive species and against Bacteroides fragilis, and it inhibited virtually all Enterobacteriaceae at 1.0 micrograms/ml or less.

Comparative in vitro activity of WIN 57273, a new fluoroquinolone antimicrobial agent.

The in vitro activity of WIN 57273, a new fluoroquinolone antimicrobial agent, was evaluated against approximately 600 bacterial isolates. The new drug was 4- to 128-fold more active than ciprofloxacin against a broad range of gram-positive organisms, with the new drug inhibiting 90% of strains of each species except Enterococcus faecium at concentrations of less than or equal to 0.25 microgram/ml. WIN 57273 was four- to eightfold less active than ciprofloxacin against many members of the family Enterobacteriaceae, but the MICs of the new drug for 90% of strains tested (MIC90s) were less than or equal to 8 micrograms/ml (range, 0.25 to 8 micrograms/ml) for all species. Branhamella catarrhalis, Haemophilus influenzae, Neisseria gonorrhoeae, and Legionella spp. were highly susceptible (MIC90s, less than or equal to 0.06 microgram/ml). WIN 57273 demonstrated excellent activity against anaerobes (MIC90s, less than or equal to 0.25 microgram/ml), and the drug was also more active than ciprofloxacin against 30 strains of Mycobacterium avium-M. intracellulare (MIC, 0.1 to 1.0 microgram/ml). The activity of WIN 57273 against gram-positive organisms was minimally affected by pH and increased at low pH (5.4) against gram-negative organisms. The bactericidal activity of WIN 57273 was demonstrated by time-kill techniques against selected organisms. The frequencies of spontaneous resistance to the new agent were low, but resistant colonies could be selected after serial passage of initially susceptible organisms through incremental concentrations of the drug.

Comparative in vitro activity of piperacillin combined with the beta-lactamase inhibitor tazobactam (YTR 830).

Combination with tazobactam substantially enhanced the activity of piperacillin against routine isolates of staphylococci, various Enterobacteriaceae, Acinetobacter anitratus, and Bacteroides fragilis. Tazobactam enhanced the activity of piperacillin more than fourfold against Pseudomonas aeruginosa spp. harboring eight of 12 plasmid-mediated beta-lactamases.

In vitro activity of cefoperazone-sulbactam combinations against cefoperazone-resistant clinical bacterial isolates.

From July 1987 to January 1988, 452 cefoperazone-resistant bacterial isolates were identified among strains subjected to routine susceptibility testing in a clinical microbiology laboratory. The 452 isolates were tested for susceptibility to cefoperazone, sulbactam, and a 2:1 combination of these drugs by agar dilution techniques. The greatest benefit of the cefoperazone-sulbactam combination was noted against Bacteroides spp. and Acinetobacter spp. The combination demonstrated clinically significant synergism against approximately 20% of strains of Pseudomonas aeruginosa.