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Biomedical subjects

A L Barry

Publications and source records attributed to A L Barry.

At least 343 records · Page 19Linked to original sources
PubMed1982

Reliability of early identifications obtained with Enterobacteriaceae-plus biochemical cards in the automicrobic system.

The AutoMicrobic system (AMS) is capable of identifying most Enterobacteriaceae within 8 h and many glucose-nonfermenting, gram-negative bacilli after 13 h of incubation. Early preliminary results can be readily obtained from the computer as the tests incubate. Data with 1,023 bacterial isolates were reviewed to determine the relative accuracy of 4-, 6-, 8-, 10-, and 13-h identifications. All AutoMicrobic system identifications with probability (P) values of less than 0.80 were considered equivocal responses which needed supplementary tests before a final report could be issued. Analysis of our data suggests that early identifications of Morganella morganii, Acinetobacter sp., Yersinia spp., Salmonella spp. (other than Salmonella typhi), Shigella spp. (other than Shigella sonnei), Enterobacter agglomerans, Pseudomonas spp. (other than Pseudomonas aeruginosa or Pseudomonas maltophilia), Klebsiella spp. (other than Klebsiella pneumoniae or Klebsiella oxytoca), Citrobacter amalonauticus, Serratia liquefaciens, or Vibrio spp. Should be considered nonspecific responses, even when P greater than or equal to 0.80. Other identifications reported after 4 h were 96% accurate. At least half of our isolates (60% of our Enterobacteriaceae) could be identified reliably within 4 h, the remaining isolates required longer incubation.

Bacteria↗
PubMed1982

Comparison of six different criteria for judging the acceptability of sputum specimens.

A series of 391 unselected expectorated sputum specimens was examined microscopically, and six different published criteria for judging the acceptability of the specimens were applied. Of the 391 specimens, 234 were found to be acceptable or unacceptable by all six criteria; 157 specimens were discrepant. By the criteria of Murray and Washington and of Barry, 25 and 23% of the specimens, respectively, were rejected; only 19 of 143 specimens which contained potential pathogens as part of their predominant microbial flora were rejected by both sets of criteria. The criteria described by Geckler et al. and Bartlett missed fewer potential pathogens; only 9 or 17% of the specimens, respectively, were found unacceptable. The criteria of Heineman and Radano and of Van Scoy resulted in the greatest percentages of specimens judged unacceptable (28 and 29%, respectively), including 19 and 24% of specimens containing potential pathogens. The reproducibility of sputum screening results was also assessed, comparing the method of Murray and Washington with that of Barry. Six separate slides were prepared from each of 45 different specimens: three samples with purulent or bloody flecks and three samples in which the specimens had been mixed with an applicator swab. Satisfactory reproducibility was observed with both criteria and both sampling methods; no significant differences in reproducibility could be documented in this limited series.

Bacteria↗
PubMed1982

Quality control limits for the agar overlay disk diffusion antimicrobial susceptibility test.

Replicate control tests were performed with the agar overlay and Kirby-Bauer techniques, using two sources of Mueller-Hinton agar. Mean zones observed with the two methods differed by 1 to 3 mm. Despite the minor differences between methods, National Committee for Clinical Laboratory Standards quality control limits which were established for the Kirby-Bauer method could also be used for the agar overlay technique.

Anti-Bacterial Agents↗
PubMed1981

Gentamicin, tobramycin, and sisomicin disc susceptibility tests. Revised zone standards for interpretation.

Studies were undertaken to reevaluate interpretive zone standards for gentamicin and tobramycin disc tests. Disc tests with an investigational aminoglycoside, sisomicin, were also evaluated. The data suggest modification of zone standards for gentamicin disc tests to R (resistant) less than or equal to 12 mm and S (susceptible) greater than or equal to 16 mm. Currently recommended standards for tobramycin disc tests (R less than or equal to 12 mm and S greater than or equal to 15 mm) were found to be satisfactory. For 10-microgram sisomicin discs, zone standards of R less than or equal to 12 mm and S greater than or equal to 15 mm were also appropriate. Although gentamicin is structurally similar to sisomicin, it was less active against Pseudomonas aeruginosa. The activity spectrum of sisomicin against the collection of 470 bacterial isolates studied more nearly resembled that of tobramycin. Data analysis suggested that tobramycin disc tests might be used to predict susceptibility to sisomicin. However, these two drugs differ in their susceptibilities to aminoglycoside-inactivating enzymes produced by some resistant strains. In those institutions where such strains are endemic, the class concept of disc testing may not be applicable.

Anti-Bacterial Agents↗
PubMed1981

Antibacterial activity of fortimicin A compared with those of five other aminoglycosides, and factors affecting susceptibility tests.

Fortimicin A, a pseudodisaccharide aminoglycoside, was found to have broad-spectrum activity against most clinically important aerobic and facultatively anaerobic bacteria, except Pseudomonas aeruginosa, some other Pseudomonas species, and streptococci. It was comparable to amikacin in its level of activity (minimum inhibitory concentrations) and spectrum of activity (except for the lack of activity on P. aeruginosa). Fortimicin A was bactericidal and was affected by cations when tested against P. aeruginosa. Minimum inhibitory concentrations were affected by the inoculum used in the susceptibility test. The drug was resistant to most aminoglycoside-inactivating enzymes, but probably is not active against permeability mutants.

Aminoglycosides↗
PubMed1981

Mezlocillin: tentative interpretive standards for disk diffusion susceptibility testing.

The susceptibility of 447 clinical bacterial isolates to mezlocillin and carbenicillin was tested by standardized agar disk diffusion and reference broth micro-dilution methods. Tentative interpretive criteria for disk susceptibility testing by using 75 micrograms mezlocillin disks are proposed: susceptible, greater than or equal to 16 mm; indeterminate, 13 to 15 mm; and resistant, less than or equal to 12 mm. These would be applicable to both Pseudomonas species and the Enterobacteriaceae, but not to Staphylococcus aureus. For S. aureus, the breakpoints for susceptible, greater than or equal to 29 mm, and resistant, less than or equal to 28 mm, hold for mezlocillin as well as for the other penicillinase-susceptible penicillins.

Bacteria↗
PubMed1981

Cefsulodin: antibacterial activity and tentative interpretive zone standards for the disk susceptibility test.

Cefsulodin (SCE-129) is a cephalosporin with a spectrum of antibacterial activity largely limited to Pseudomonas aeruginosa and Staphylococcus aureus. Cefsulodin was compared with carbenicillin, ticarcillin, mezlocillin, and piperacillin against 779 nonenteric gram-negative bacilli and staphylococci collected from five geographically separate institutions. Against P. aeruginosa, cefsulodin was somewhat more active than piperacillin and much more active than other penicillins. In addition, cefsulodin was active against penicillinase-producing strains of S. aureus. Collaborative efforts in three laboratories led to the following tentative zone size breakpoints for 30-micrograms cefsulodin disks: susceptible greater than or equal to 18 mm (minimal inhibitory concentration) [MIC] less than or equal to 16 micrograms/ml) and resistant less than or equal to 14 mm (MIC greater than or equal to 64 micrograms/ml). These zone standards are still tentative since the dosage schedule has not yet been defined and sufficient clinical experience has not yet been gathered to support the validity of these MIC breakpoints.

Acinetobacter↗
PubMed1981

Cefmenoxime (SCE-1365), a new cephalosporin: in vitro activity, comparison with other antimicrobial agents, beta-lactamase stability, and disk diffusion testing with tentative interpretive criteria.

The in vitro activity of cefmenoxime (SCE-1365) was evaluated in a multiphased collaborative investigation. Over 7,500 consecutive clinical isolates were tested in five laboratories, and greater than 90% of the following organisms were inhibited by cefmenoxime at the following concentrations: Enterobacteriaceae and non-enterococcal streptococci, </=0.125 mug/ml; Staphylococcus aureus, </=2.0 mug/ml; and nonfermenting gram-negative bacilli and Bacteroides fragilis group, </=32 mug/ml. Both beta-lactamase-producing and -nonproducing Haemophilus influenzae and Neisseria gonorrhoeae were inhibited by cefmenoxime at </=0.03 mug/ml. The spectrum of cefmenoxime was similar to that of other, newer cephalosporins, particularly cefotaxime. A pronounced inoculum effect was found with some species upon increasing inocula from 10(5) to 10(7) colony-forming units per ml, resulting in an approximate eightfold increase in minimum inhibitory concentrations. Cefmenoxime was bactericidal when tested with inocula of 10(5) colonyforming units per ml, and mean differences between the minimum inhibitory concentration and the minimum lethal concentration were less than one log(2) dilution. No significant hydrolysis of cefmenoxime by five different beta-lactamases was detectable, and cefmenoxime exhibited marked inhibition of type I beta-lactamases. Regression and error rate-bounded analyses of results of disk diffusion and reference broth microdilution susceptibility tests were performed on 421 bacterial isolates, and the following tentative zone size breakpoints are proposed: >/=22 mm, susceptible; </=14 mm, resistant; and 15 to 21 mm, moderately susceptible (indeterminate). These data and cross-resistance studies with other newer cephalosporins indicate marked similarity of in vitro activity within this group of drugs, particularly between cefmenoxime, moxalactam, and cefotaxime. Any one of these could serve as the representative for the disk diffusion testing of this group of drugs if comparable minimum inhibitory concentration breakpoints were used for each drug.

Bacteria↗
PubMed1981

In vitro antimicrobial activity evaluation of cefodizime (HR221), a new semisynthetic cephalosporin.

Cefodizime (HR221) is a new alpha-methoxyimino cephalosporin developed by Hoechst-Roussel with a reported serum half-life of over 2 h. In vitro susceptibility studies showed that the cefodizime spectrum includes all those Enterobacteriaceae, staphylococci, Streptococcus spp., Haemophilus spp., and Neisseria spp. normally susceptible to cefotaxime (HR756) or ceftizoxime (FK749) or both. Cefodizime was less active (two- to eightfold) than cefotaxime or ceftizoxime against some enteric species, but was the most potent drug against some strains of Morganella spp. and Proteus vulgaris. Enterococci, methicillin-resistant Staphylococcus aureus, and most Pseudomonas spp. were resistant to cefodizime (median minimum inhibitory concentrations, greater than or equal to 64 microgram/ml). Acinetobacter spp. and Pseudomonas aeruginosa strains required cefodizime concentrations of 32 microgram/ml to inhibit 50% of tested strains. Cefodizime was very stable to hydrolysis by Richmond-Sykes type I, II, III, and IV beta-lactamases, as well as the enzyme derived from Bacillus cereus. The reference PADAC and nitrocefin substrate hydrolysis by a type I beta-lactamase was markedly inhibited (greater than 80%) by cefodizime at concentrations 0.4 to 4% of substrate concentration. Cefodizime was active against 43% of bacteria which were resistant to cephalothin and cefamandole and against 58% of those resistant to aminoglycosides.

Bacteria↗
PubMed1981

Evaluation of the Sceptor microdilution antibiotic susceptibility testing system: a collaborative investigation.

A multiwell, dried antimicrobial agent susceptibility test system, Sceptor (BBL Microbiology Systems, Cockeysville, Md.), was tested. The system was compared directly with a reference microdilution method by using two collections of stock cultures and 305 fresh clinical isolates. Sceptor was found to be in agreement (+/- log2 dilution) with the reference microdilution method in 96.9 to 98.3% of 9,840 minimal inhibitory concentration determinations performed on stock strains and 95.0% of 7,308 minimal inhibitory concentrations obtained from the clinical isolates. The intralaboratory and interlaboratory reproducibility on stock strains was 97.6 and 97.2%, respectively. The intralaboratory reproducibility for the clinical isolates was 96.9%. Sceptor accurately categorized representative challenge strains of methicillin-resistant staphylococci, beta-lactamase-producing bacteria, organisms producing other antimicrobial agent-inactivating enzymes, and permeability mutants as resistant. Only 0.2% very major errors (false-sensitive minimal inhibitory concentrations by Sceptor) were identified among the clinical isolate test results, the majority being clinically insignificant. The product is accurate and reliable, has a long shelf life, and seems applicable for routine use in clinical laboratories.

Anti-Bacterial Agents↗
PubMed1981

Gentamicin and amikacin disk susceptibility tests with Pseudomonas aeruginosa: definition of minimal inhibitory concentration correlates for susceptible and resistant categories.

With currently recommended disk susceptibility tests, minimal inhibitory concentration correlates for amikacin were greater than 16 micrograms/ml for resistance and less than or equal to 12 micrograms/ml (not less than or equal to 8 micrograms/ml) for susceptibility. For gentamicin, they were greater than 8 micrograms/ml for resistance and less than or equal to 6 micrograms/ml (not less than or equal to 4 micrograms/ml) for susceptibility. Minor discrepancies between disk tests and minimal inhibitory concentration determinations will occur if only doubling dilutions of drug are used for measuring minimal inhibitory concentration values.

Amikacin↗
PubMed1981

Quality control limits for ampicillin, carbenicillin, mezlocillin, and piperacillin disk diffusion susceptibility tests: a collaborative study.

A multilaboratory in vitro study was carried out to determine disk diffusion susceptibility testing quality control limits for two new semisynthetic penicillins, mezlocillin and piperacillin. Existing limits for carbenicillin and ampicillin were reevaluated. Multiple tests (which followed standards set by the National Committee for Clinical Laboratory Standards ASM-2 revised) were performed in nine laboratories by different technologists using disks and Mueller-Hinton agar from different manufacturers. Clinically significant differences between disks produced by different manufacturers were not noted. Inhibitory zone diameter measurements from all laboratories were analyzed, and upper and lower control limits were established by using the overall median +/-0.5 the median range of the individual laboratory measurements as determining parameters. Close agreement of the data in this study with the results of national proficiency testing and quality control programs for ampicillin and carbenicillin supports the validity of our approach to making initial recommendations for quality control guidelines for new antimicrobial agents.

Ampicillin↗
PubMed1980

Evaluation of the Sensititre system for quantitative antimicrobial drug susceptibility testing: a collaborative study.

This three-center collaborative study was conducted to evaluate samples of Sensititre antimicrobial microdilution panels (GIBCO/INVENEX). Sensititre minimum inhibitory concentrations of 27 bacterial isolates were compared with those obtained by a reference microdilution method. The Sensititre and microdilution minimum inhibitory concentrations were equivalent within +/- 1 dilution in 87.6% of the comparable test results. Intralaboratory reproducibilities of the Sensititre and microdilution endpoints were equivalent with 80.4 and 82.4%, respetively, of on-scale endpoints in absolute agreement. Sensititre was more reproducible among laboratories, with nearly a 10% greater agreement of triplicate results. The Sensititre microdilution test as evaluated gave results which were essentially equivalent to those obtained with a standardized microdilution method.

Aminoglycosides↗
PubMed1980

Cefoperazone (T-1551), a new semisynthetic cephalosporin: comparison with cephalothin and gentamicin.

The in vitro activity of cefoperazone (T-1551) against almost 9,000 recent clinical isolates at six institutions was tested and compared with that of cephalothin and gentamicin. The modal minimum inhibitory concentrations of cefoperazone were 16- and 4-fold less than those of cephalothin and gentamicin, respectively, against 5,503 strains of Enterobacteriaceae. Species normally resistant to cephalothin, such as indole-positive protease and enterobacters, were almost universally susceptible to cefoperazone. Cefoperazone demonstrated activity comparable to gentamicin against Pseudomonas aeruginosa and other pseudomonads.

Bacteria↗
PubMed1980

Moxalactam (LY127935), a new semisynthetic 1-oxa-beta-lactam antibiotic with remarkable antimicrobial activity: in vitro comparison with cefamandole and tobramycin.

Moxalactam (LY127935) exhibited greater in vitro activity than cefamandole and tobramycin against clinical isolates of Enterobacteriaceae, Aeromonas hydrophila, and Pseudomonas maltophilia. The activities of the three drugs against other microorganisms were as follows: for staphylococci, cefamandole = tobramycin greater than moxalactam; for streptococci, cefamandole greater than moxalactam greater than tobramycin; and for Pseudomonas aeruginosa, tobramycin greater than moxalactam greater than cefamandole. Moxalactam also demonstrated significant activity against the Bacteroides fragilis group and other anaerobes. Moxalactam was comparable to cefotaxime (HR756) in its inhibition of cephalothin-resistant and aminoglycoside-resistant clinical isolates.

Aminoglycosides↗
PubMed1980

Cefotaxime: in vitro activity and tentative interpretive standards for disk susceptibility testing.

Tested against 9,412 recent clinical isolates, cefotaxime exhibited 8 to 64 times greater activity against the Enterobacteriaceae than did cephalothin and two to four times greater activity against Pseudomonas aeruginosa, but only one-half to one-eighth the activity of cephalothin against staphylococci. Using 420 different clinical isolates, but with comparable minimal inhibitory concentration (MIC) distributions, disk diffusion-MIC regression analyses were performed, using 5- and 30-micrograms cefotaxime disks. Cefotaxime MIC susceptible and resistant breakpoints of less than or equal to 8 and greater than 32 micrograms/ml are tentatively proposed. Based on the MIC breakpoints, the data showed the best discrimination among the three susceptibility categories (susceptible, indeterminate, and resistant) when the 30-micrograms cefotaxime disk was used. The zone diameter breakpoints as determined by the error rate-bounded method and regression analysis were greater than or equal to 23 mm for susceptible, 15 to 22 mm for indeterminate, and less than or equal to 14 mm for resistant.

Bacteria↗