Biomedical subjects
S D Allen
Publications and source records attributed to S D Allen.
The temperature optimum of the intestinal flora of the rat.
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Antimicrobial activity of cefpirome. An update compared to five third-generation cephalosporins against nearly 6000 recent clinical isolates from five medical centers.
Cefpirome, cefotaxime, ceftazidime, cefoperazone, ceftizoxime, and ceftriaxone were tested against approximately 6000 fresh clinical isolates from five medical centers. For 3031 strains of Enterobacteriaceae tested, cefpirome consistently had the lowest MIC50s and lowest percentage of resistant strains. Cefpirome was also the most active agent against the 2138 Gram-positive cocci tested; Staphylococcus haemolyticus was uniformly resistant to all agents tested. Against 791 nonenteric Gram-negative bacilli, the activity of cefpirome was most comparable to that of cefoperazone and slightly less active than ceftazidime. Among the current third-generation cephalosporins, cefotaxime and cefoperazone emerged as having better overall balanced activity. Ceftazidime displayed poorest coverage against Enterobacteriaceae and Gram-positive organisms. Ceftizoxime also provided compromised coverage of staphylococci and nonenteric Gram-negative bacilli. Cefpirome remains as active as originally described in 1984 and possesses a slightly wider spectrum of activity against contemporary aerobic pathogens compared to currently marketed third-generation cephalosporins.
Multicenter comparison of the high volume (10 ml) NR BACTEC PLUS system and the standard (5 ml) NR BACTEC system.
This multicenter study was designed to compare the new BACTEC PLUS system (nonradiometric), which utilizes an 8- to 10-ml blood inoculum in a resin-containing medium, to the standard BACTEC (nonradiometric) without resins and 5-ml blood inoculum. There were 12,341 compliant sets studied, yielding 1331 positives, with 1099 sets deemed clinically significant. Overall the BACTEC PLUS showed an enhanced recovery of 33% (p less than 0.001) over its standard counterpart, with significant yield increased in the staphylococci (p less than 0.001), streptococci (p less than 0.002), pseudomonads (p less than 0.002), Enterobacteriaceae (p less than 0.001), and other aerobic Gram negatives (p less than 0.02). The enhanced performance increased to 53% if the patient was receiving any antibiotics at the time the blood was cultured. In patients known to be free of antibiotics at the time of blood draw, there was still an increased yield of 18%. The new system detected positivity at least one reading sooner than twice as often as the converse, and confirmed septic episodes significantly more often (21% overall) (41% on antibiotics) (15% no antibiotics). The BACTEC PLUS has distinct advantages over its low blood volume, nonresin counterpart.
In vitro activity of cefpodoxime compared with other oral cephalosporins tested against 5556 recent clinical isolates from five medical centers.
A multicenter study was conducted in which the in vitro activity of cefpodoxime (the active metabolite of the prodrug ester cefpodoxime proxetil) was compared with those of cefixime, cefuroxime, cefaclor, cefadroxil, and clarithromycin against 5556 recent clinical isolates. Cefpodoxime demonstrated potent activity against members of the Enterobacteriaceae, in particular against species generally resistant to the established oral cephalosporins such as Proteus vulgaris [minimum inhibitory concentration (MIC)50, 0.12 microgram/ml], Providencia rettgeri (MIC50, 0.015 microgram/ml), and Serratia marcescens (MIC50, 2 micrograms/ml). Cefpodoxime was very effective against the fastidious organisms most frequently associated with respiratory infections, such as Streptococcus pneumoniae (MIC90, 0.12 microgram/ml), Haemophilus influenzae (MIC90, 0.12 microgram/ml), and Moraxella catarrhalis (MIC90, 1 microgram/ml). In contrast to other orally administrated third-generation cephalosporins (cefixime or ceftibuten), cefpodoxime demonstrated reasonable activity against oxacillin-susceptible staphylococci, with MIC50 ranging from 1 to 2 micrograms/ml. All cephalosporins tested demonstrated poor activity against Pseudomonas spp., Xanthomonas spp., Enterococcus spp., and oxacillin-resistant staphylococci. Cefpodoxime had the widest spectrum of activity of all tested oral cephalosporins.
In vitro comparison of E4868, a new trifluoroquinolone, with ciprofloxacin and temafloxacin tested against 5192 recent clinical isolates from five medical centers.
The in vitro activity of E4868 was compared with that of ciprofloxacin and temafloxacin in a multicenter study. More than 90% of Enterobacteriaceae and 82% of the 651 isolates of Pseudomonas aeruginosa, as well as > 95% of the oxacillin-susceptible staphylococci, 100% of the beta-hemolytic streptococci, and 76% of the enterococcal isolates were susceptible to E4868 (minimum inhibitory concentrations, < or = 2 micrograms/ml). E4868 was generally equivalent or slightly less active than ciprofloxacin against the Enterobacteriaceae and Pseudomonas and more active against staphylococci and beta-hemolytic streptococci. The activity of E4868 was generally equivalent to or slightly greater than that of temafloxacin against all major groups of organisms.
Multilaboratory evaluation of the in vitro activity of 13 beta-lactam antibiotics against 1474 clinical isolates of aerobic and anaerobic bacteria.
The in vitro activity of 13 beta-lactam antibiotics against 1474 recent clinical isolates was evaluated in a multilaboratory study. The most active antibiotic tested in this study was imipenem (98.5% of the strains were susceptible), followed by ticarcillin-clavulanate (91.4%), cefoperazone (90.0%), ceftazidime (87.9%), cefotaxime (87.7%), ceftriaxone (87.0%), ceftizoxime (86.3%), cefotetan (78.5%), ampicillin-sulbactam (77.9%), cefoxitin (73.5%), cefuroxime (70.9%), cefonicid (64.5%), and cefazolin (57.9%).
Multilaboratory evaluation of an agar diffusion disk susceptibility test for rapidly growing anaerobic bacteria.
A multilaboratory collaborative study was undertaken to determine whether the anaerobic disk diffusion test of Horn et al. could be performed reproducibly and accurately. Tests with nine different antimicrobial disks were evaluated. Reproducibility of the agar diffusion disk method was similar to that of the reference agar dilution test procedure. The anaerobic disk diffusion procedure was found to be a potentially useful method for testing some antimicrobial agents against rapidly growing anaerobes belonging to the Bacteroides fragilis group. These promising results warrant further investigations and validations.
Piperacillin/tazobactam (YTR 830) combination. Comparative antimicrobial activity against 5889 recent aerobic clinical isolates and 60 Bacteroides fragilis group strains.
Piperacillin combined with tazobactam (formerly YTR 830) was tested at a ratio of 8:1 against 5889 aerobic isolates and 50 strains from the Bacteroides fragilis group. Imipenem was the most active agent tested against Enterobacteriaceae (99.3% at less than or equal to 4 micrograms/ml), ceftazidime was most effective against nonenteric Gram-negative bacilli (80.7% at less than or equal to 8 micrograms/ml), and piperacillin/tazobactam possessed a superior spectrum against Gram-positive cocci (92.2% at less than or equal to 16/2 micrograms/ml). Against all aerobic strains, piperacillin/tazobactam had a spectrum (90.3% at less than or equal to 16/2 micrograms/ml) comparable to imipenem (93.6% at less than or equal to 4 micrograms/ml) and was distinctly greater than that of ticarcillin/clavulanic acid (73.3% at less than or equal to 16/2 micrograms/ml) and ceftazidime (75.5% at less than or equal to 8 micrograms/ml). Against the B. fragilis group isolates, all piperacillin/tazobactam MICs were less than or equal to 64/8 micrograms/ml. This activity was superior to piperacillin alone (MIC:50, 8-64 micrograms/ml) and cefoxitin (MIC50, 4-64 micrograms/ml). Piperacillin/tazobactam appears to be a promising parenteral antimicrobial combination, with a spectrum effective against a wide variety of clinical pathogens.