PubMed Health⌕ Search

Biomedical subjects

C O Quall

Publications and source records attributed to C O Quall.

18 recordsLinked to original sources
PubMed1985

Pasteurella multocida in an infected tiger bite.

We report an unusual case of Pasteurella multocida wound infection caused by a tiger bite. We investigated the normal fang flora of large zoo cats and found P multocida in cultures from seven tigers, three of four leopards, and one lynx. Sucrose fermentation was found to be highly media dependent and unpredictable. The literature relative to P multocida in bite-wound infections is reviewed with special reference to bites by animals other than cats and dogs. With the addition of the present case, the animals involved have been two rats, two opossums, two lions, one horse, one rabbit, one boar, one panther, and one tiger.

Adult↗
PubMed1984

Antimicrobial resistance in Haemophilus isolates: a Minnesota experience and literature review.

Annual ampicillin susceptibility rates for Haemophilus influenzae isolates at the St. Paul-Ramsey Medical Center gradually decreased from 100% in 1974 to 83.3% in 1980 and then remained stable at 88.90%. Penicillin susceptibility rates were similar to those for ampicillin. Ampicillin rates were source dependent: eye 95%, respiratory 90%, miscellaneous sources 82%, and blood and CSF 80%. Rates for Haemophilus parainfluenzae varied and showed no trend. H. parainfluenzae isolates were distinctly less susceptible to penicillin (70%) than to ampicillin (96%). H. influenzae isolates were highly susceptible to chloramphenicol (99.6%) and tetracycline (97.5%), with the latter also showing source dependency. Characterization of isolates for colony morphology and hemolysis showed no clinical relevancy. Ampicillin and penicillin MICs were determined for 128 clinical isolates saved in stock culture during 1978-1983. All 19 resistant isolates (MIC greater than or equal to 4 micrograms/mL) were resistant to both penicillin and ampicillin and produced beta-lactamase. Eight had penicillin MICs of 1 or 2 micrograms/mL and three had ampicillin MICs of 1 or 2 micrograms/mL. The significance of isolates with MICs of 1-2 micrograms/mL is discussed in relation to our findings and a review of the literature.

Ampicillin↗
PubMed1984

Evaluation of the automicrobic system for susceptibility testing of Pseudomonas aeruginosa to gentamicin, tobramycin, and amikacin.

The AutoMicrobic system (AMS; Vitek Systems, Inc., Hazelwood, Mo.) was studied for its ability to produce accurate and precise MIC interpretations for Pseudomonas aeruginosa susceptibility to gentamicin, tobramycin, and amikacin. MICs were determined in parallel on 200 selected P. aeruginosa isolates by using the AMS discrete-integer MIC program AMS p12.ROB for interpretation of the AMS Gram-Negative General Susceptibility Urinary Card, and a reference small-integer broth microdilution test. Parallel AMS and broth microdilution MICs were also replicated for three selected strains of P. aeruginosa for which MICs were representative of the dilution test ranges. For the 200 P. aeruginosa isolates, mean AMS MICs were significantly larger than the reference test mean MICs, coefficients of variation were approximately double those of the reference test, and correlation coefficients were unacceptably low for each antimicrobial agent. MIC replication studies for the three selected P. aeruginosa strains showed comparable AMS and reference mean MICs in the lower portions of the dilution ranges, significantly higher AMS mean MICs in the upper portions, and mean coefficients of variation of 63 and 9.6%, respectively, for replicated AMS and reference MICs. These results indicate that the AMS, in its present stage of development, does not produce acceptable MIC measurements for P. aeruginosa susceptibility to gentamicin, tobramycin, and amikacin.

Amikacin↗
PubMed1984

Evaluation of the AutoMicrobic system for identification and susceptibility testing of gram-negative bacilli.

The AutoMicrobic system (AMS) (Vitek Systems, Inc., Hazelwood, Mo.) was compared with the API-20E system for the identification of gram-negative bacilli by using 380 stock clinical isolates and 377 immediately encountered fresh clinical isolates. For the stock isolates, with Enterobacteriaceae-Plus Biochemical Cards and automated interpretation, 364 (95.8%) were in agreement to the species level. For the fresh clinical isolates, agreement at the genus and species levels was 89.7 and 85.9%, respectively, when Enterobacteriaceae-Plus Cards were interpreted by the AMS. Manual interpretation of Enterobacteriaceae-Plus Biochemical Cards improved species level agreement to 91.0%. Subsequent retesting of all discrepant isolates with the Gram-Negative Identification Card resulted in significant improvement of results, and for the stock and fresh clinical isolates, species level agreement was 98.7 and 97.3%, respectively. AMS susceptibility testing was evaluated by comparing ampicillin and cephalothin MICs determined in parallel by AMS and a reference broth microdilution test for stock isolates, and by comparison of AMS and standardized disk agar diffusion test results for fresh clinical isolates. For the stock isolates, AMS mean integer MICs approximated microdilution mean integer MICs with AMS, providing excellent MIC replicability. For ampicillin and cephalothin, 50 and 46.8%, respectively, of AMS integer MICs were within +/- 1 microgram/ml of the reference values, and 89.3 and 63.1% of AMS integer MICs were within +/- 2 micrograms/ml of the reference values. For the fresh clinical isolates, AMS and reference results were in disagreement for 4.5% of the antimicrobial agents tested, with 2.3% as a combination of "major" and "very major" errors.

Ampicillin↗
PubMed1983

Error rates associated with the use of recently proposed breakpoints for testing Pseudomonas aeruginosa versus gentamicin, tobramycin, and amikacin by the standardized disk agar diffusion test.

Two hundred fifteen Pseudomonas aeruginosa isolates were tested in parallel by the disk agar diffusion test, using a standardized agar preparation, and by a microbroth test, using dilutions differing by small arithmetic increments. For gentamicin, recently proposed breakpoints of resistance (R) less than or equal to 12 mm and susceptibility (S) greater than or equal to 16 mm produced error rates of 20 and 6.8%, respectively. Limiting the error rate for susceptible interpretations to less than or equal to 2% produced a widening of the intermediate zone to include 67.4% of the isolates tested. For tobramycin, the recently proposed breakpoints of R less than or equal to 12 mm and S greater than or equal to 15 mm were associated with error rates of 66.7 and 1.4%, respectively. Breakpoints of R less than or equal to 12 mm and S greater than or equal to 13 mm were demonstrated to be equally effective when the error rate for susceptible interpretations was limited to less than or equal to 2% by error rate-bound analysis. For amikacin, proposed breakpoints of R less than or equal to 14 mm and S greater than or equal to 17 mm were associated with error rates of 27.3 and 3.2%, respectively. Limiting the error rates for susceptible interpretations to less than or equal to 2% required breakpoints of R less than or equal to 14 mm and S greater than or equal to 18 mm. The ability to establish effective susceptibility breakpoints for tobramycin and amikacin appeared not to be related to the disk agar diffusion test process itself but rather to the high degree of susceptibility of the P. aeruginosa population. These findings severely limit the usefulness of the disk agar diffusion procedure for testing P. aeruginosa versus the aminoglycosides. For this purpose, we recommend dilution tests which employ small arithmetic increment schemes.

Amikacin↗
PubMed1983

Comparative evaluation of the micro-media system, sceptor, and MIC-2000 microdilution methods for testing Pseudomonas aeruginosa against gentamicin, tobramycin, and amikacin.

Minimum inhibitory concentrations (MICs) for selected strains of Pseudomonas aeruginosa versus gentamicin, tobramycin, and amikacin were replicated in parallel with MMS (Micro-Media Systems, Potomac, Md). Sceptor (BBL Microbiology Systems, Cockeysville, Md), and matching MIC-2000 (Dynatech Laboratories, Inc., Alexandria, Va.) twofold dilution panels and with MIC-2000 panels with dilutions differing by small arithmetic increments. The three microdilution systems produced comparable modal MICs. However, dispersion about modal values was greater for MMS than for either Sceptor or comparable MIC-2000 twofold panels. MICs were best define by MIC-2000 panels with dilutions differing by small arithmetic increments, for which 72.9% of MICs were modal, 95.4% were one small increment step or less from the modal value, and 100% were two small-increment steps or less form the modal value. The similarity of MIC replication for Sceptor and MIC-2000 twofold panels suggests the possibility of using small increment dilutions by Sceptor.

Amikacin↗
PubMed1983

Evaluation of the AutoSCAN-3 and Sceptor systems for Enterobacteriaceae identification.

To evaluate the accuracy and cost effectiveness of the AutoSCAN-3 (Micro-Scan Systems of America, Sacramento, Calif.) and Sceptor (BBL Microbiology Systems, Cockeysville, Md.) systems for identification of members of the Enterobacteriaceae, we performed parallel tests on 678 stock cultures of well-characterized clinical isolates of Enterobacteriaceae. Automated results by AutoSCAN-3 correctly identified 95.1% at the genus level and 94.9% at the species level. However, 15 of 42 Shigella isolates were misidentified as members of other genera. In contrast to the automated results, visual interpretation of panels produced 97.9% agreement at the genus level, missing only three Shigella isolates. Sceptor correctly identified 96.8% at the genus level and 93.4% at the species level. Of 42 Shigella isolates, 3 were missed and were designated as Salmonella spp. Although all Salmonella spp. were correctly identified, six other isolates were misidentified as Salmonella spp. Test costs were found to be comparable for each system, with the cost per test increasing markedly with fewer than 10 to 15 tests performed per day.

Bacteriological Techniques↗
PubMed1982

Broth microdilution testing of Pseudomonas aeruginosa and aminoglycosides: need for employing dilutions differing by small arithmetic increments.

The use of dilutions differing by small arithmetic increments was studied as a means for improving the definition and measurement of minimum inhibitory concentrations and precision parameters for testing Pseudomonas aeruginosa versus the aminoglycosides by the broth microdilution test. For five strains of P. aeruginosa versus gentamicin, tobramycin, and amikacin, comparisons were made of minimum inhibitory concentrations which were replicated in parallel by using three microdilution systems: small increment panels prepared by us, modified twofold dilution panels prepared by us, and similar modified twofold dilution panels obtained commercially. The small increment dilutions were prepared to differ by concentrations of 1.0 microgram/ml for gentamicin and tobramycin and by 2.0 micrograms/ml for amikacin. Use of the small increment dilutions resulted in the ability to measure minimum inhibitory concentrations at more closely spaced intervals than those dictated by modified twofold dilution schemes, and confidence limits were significantly improved. The average coefficient of variation for the small increment microdilution test results was 9.5%, with 99.5% of minimum inhibitory concentrations falling within +/- 2 small increment dilutions from their modal values.

Aminoglycosides↗
PubMed1981

Comparison of minimum inhibitory concentration values determined by three antimicrobic dilution methods for Pseudomonas aeruginosa.

This investigation compares minimum inhibitory concentration measurements by three antimicrobic dilution methods for Pseudomonas aeruginosa versus seven antimicrobics. Minimum inhibitory concentrations were measured for 650 P. aeruginosa clinical isolates and for repeated tests with P. aeruginosa ATCC 27853 versus gentamicin, tobramycin, amikacin, netilmicin, sisomicin, carbenicillin, and ticarcillin, using the macro-broth, micro-broth, and agar dilution methods. For all antimicrobics, it was found that the micro-broth and agar dilution methods produced comparable minimum inhibitory concentration measurements, which were found to lie 1 to 2 double dilution steps below those determined by the macro-broth method. Acceptably replicability was found for both the macro-broth and the agar dilution methods. The micro-broth method showed less replicability, with 4.7% of minimum inhibitory concentration values lying +/- 2 or more double dilution steps from the modal value. It is important to recognize such differences if micro-broth or agar dilution methods are substituted for the macro-broth method.

Aminoglycosides↗
PubMed1981

Inability of the API-20E system to speciate the fluorescent group of pseudomonads.

One thousand randomly selected clinical isolates of the fluorescent group of Pseudomonas were speciated in parallel by the API-20E system and by a classic microbiologic 17-test battery. The classic battery identified the isolates as 993 Pseudomonas aeruginosa, five Pseudomonas putida, and two Pseudomonas fluorescens. To augment the P. putida and P. fluorescens data, 52 reference isolates were also tested in parallel. API-20E was found to identify 99% of P. aeruginosa as P. aeruginosa. However, the 59 P. putida and P. fluorescens isolates were not accurately identified and were designated 58% P. aeruginosa, 24% P. stutzeri, 16% ambiguous categories, and only 2% in agreement with the classic designation. These findings indicated that the API-20E system does not accurately identify the non-P. aeruginosa fluorescent pseudomonads and that errors in P. aeruginosa designations will increase as the percentages of P. putida and P. fluorescens increase in the population sample.

Bacteriological Techniques↗
PubMed1981

An evaluation of burn wound quantitative microbiology. I. Quantitative eschar cultures.

The reliability of quantitative data from burn wound biopsy cultures was investigated. This was done by comparing the recovery of microorganisms from a series of burn wound eschar biopsy specimens that were each divided into two approximately equal portions and cultured in parallel. The results indicate that a microorganism present in the burn wound site in any quantity has at least a 25% chance of being missed by a single quantitative eschar culture. For recovery levels corresponding to quantitative breakpoints that have been proposed to be predictive of burn wound sepsis, only 38% of paired quantitative results agreed within the same log10 unit, and 44% differed by +/- 2 log10 units or more. These findings indicate that quantitative results derived from burn wound biopsy cultures are unreliable and may be significantly misleading when used for decision-making relative to patient care.

Bacteria↗
PubMed1981

An analysis of error rates for disc agar-diffusion testing of Pseudomonas aeruginosa versus aminoglycosides.

Five hundred thirty-five recent clinical isolates of Pseudomonas aeruginosa were tested in parallel by the standardized disc agar-diffusion test and a micro-broth dilution test to evaluate the error rates associated with the use of both fixed indeterminate-zone breakpoints and floating indeterminate-zone breakpoints for assessing susceptibility to amikacin, gentamicin, and tobramycin. Error rate-bound analysis showed that unacceptably high rates of error were associated with the use of all fixed breakpoints. Error rates were improved when the floating indeterminate-zone principle was used, but rates still remained unacceptably high. These findings indicate the disc agar-diffusion test should not be used for testing the susceptibility of P. aeruginosa to the aminoglycosides.

Amikacin↗
PubMed1981

Evaluation of the repliscan system for Enterobacteriaceae identification.

A total of 1,013 isolates of Enterobacteriaceae were identified in parallel by the Repliscan (Cathra International, Ontario, Canada) and API 20E (Analytab Products, Plainview, N.Y.) systems. There was a 62% agreement at the genus level between the two systems. Of the 38% discrepant results, Repliscan classified 22% as "biochemical pattern not on file," 8% as a multiple-genus group which included the API 20E identification, and 8% as a genus other than that designated by API 20E. Relative to the various genera, Repliscan agreed with API 20E as follows: Escherichia coli, 80%; Klebsiella spp., 76%; Citrobacter spp., 75%; Proteus spp., 69%; Providencia spp., 54%; Serratia spp., 49%; Enterobacter spp., 25%; Shigella spp., 4%; and Salmonella spp., 0%. Repliscan identified 35% of Enterobacter spp. isolates as Citrobacter spp., 91% of Shigella spp. isolates as a multiple-choice-genus group, and 67% of Salmonella spp. isolates as "biochemical pattern not on file." Repliscan agreed with API 20E at the species level as follows: E. coli, 80%; Klebsiella spp., 56%; Citrobacter spp., 66%; Proteus spp., 55%; Providencia spp., 46%; Serratia spp., 39%; Enterobacter spp., 18%; Shigella spp., 4%; and Salmonella spp., 0%. These findings indicate that the Repliscan system in its present stage of development does not reliably identify the Enterobacteriaceae.

Bacteriological Techniques↗
PubMed1981

Evaluation of the Repliscan II System for identification of Enterobacteriaceae.

In a precious report (Woolfrey et al., J Clin. Microbiol. 13:58-61, 1981), we indicated that the Repliscan system did not reliably identify Enterobacteriaceae. Recent improvements in the system prompted us to evaluate Repliscan II (Cathra International, Inc., St. Paul, Minn.) by using representative isolates of the population sample previously used to test the system. Isolates (692) representing eight genera were identified in parallel by the Repliscan II and API 20E (Analytab Products, Plainview, N.Y.) systems. Isolates given different identifications by the two systems were assigned reference identifications by using classical microbiological methods. Repliscan II identified 95.2% correctly, 4.0% incorrectly, and 0.7% as unknown. API 20E identified 99.4% correctly, 0.6% incorrectly, and none as unknown. Repliscan II correctly identified Salmonella and Shigella spp. to the genus level and isolates of six other genera to the species level as follows: Salmonella spp., 100%; Shigella spp., 97.7%; Escherichia spp., 95.2%; Citrobacter spp., 82.1%; Enterobacter spp., 85.2%; Klebsiella spp., 98.6%; Proteus spp., 97.2%; and Serratia spp., 97.9%. These findings indicate that Repliscan II is a significantly improved system and provides acceptable identification of Enterobacteriaceae.

Bacteriological Techniques↗
PubMed1980

Evaluation of a semiautomated micro-broth dilution system for determing minimum inhibitory concentrations of antimicrobics.

This study investigates the dispensing and inoculating characteristics of the MIC-2000 micro-broth dilution system and compares its ability to determine minimum inhibitory concentrations with that of the reference macro-broth dilution method. Micro-well filling showed a coefficient of variation of 6.8%, and micro-well inoculating showed a coefficient of variation of 6.1%. The reference macro-broth dilution method showed a coefficient of variation of 2.9% for dispensing and a coefficient of variation of 2.9% for inoculating. Ninety-three and eight tenths per cent of macro-broth minimum inhibitory concentrations duplicated the macro-broth modal value, with 100% falling within +/-1 double-dilution step. Eighty-five per cent of micro-broth minimum inhibitory concentrations duplicated the micro-broth modal value, with 99.8% falling within +/-1 double-dilution step. When the micro-broth results were evaluated using the macro-broth modal minimum inhibitory concentration value as a reference point, 55.8% duplicated the macro-broth modal value, with 4.7% falling above it and the remainder being skewed below it, with 6.2% at -2 double-dilution steps. These findings indicate that minimum inhibitory concentrations measured by the MIC-2000 system are somewhat lower than those of the reference macro-broth method. As a result, the micro-broth minimum inhibitory concentrations show a wider dispersion when referenced to the macro-broth modal minimum inhibitory concentration than when referenced to their own modal value.

Evaluation Studies as Topic↗
PubMed1979

Evaluation of the moving intermediate zone concept for determing susceptibility of pseudomonads to gentamicin by the standardized disk agar-diffusion test.

The usefulness of the moving intermediate zone concept for improving the performance of the standardized disk agar-diffusion test in measuring susceptibility of the fluorescent group of pseudomonads to gentamicin was studied. For this purpose, a 3-mm moving intermediate zone lying --3 mm and --6 mm below that measured for the quality control microorganism Pseudomonas aeruginosa, ATCC 27853, and a wider moving intermediate zone lying --2 mm and --7 mm below that for the quality control microorganism were investigated. Data from the authors' previous study of the usefulness of using fixed breakpoints and fixed zones for assessing susceptibility of the fluorescent pseudomonads to gentamicin were used for this analysis. The results indicate that both the 3-mm moving intermediate zone and the wider 5-mm moving intermediate zone produced unacceptably high rates of error for testing the susceptibility of the fluorescent group of pseudomonads to gentamicin by the standardized disk agar-diffusion test.

Fluorescence↗
PubMed1978

Inability of the standardized disk agar-diffusion test to measure susceptibility of the fluorescent group of pseudomonads to gentamicin.

Four hundred thirteen clinical isolates of fluorescent pseudomonads consisting of 286 Pseudomonas aeruginosa and 127 organisms of the Pseudomonas fluorescent group were tested for susceptibilities to gentamicin by the broth-dilution method and by the standardized disk agar-diffusion test, using Mueller-Hinton agar from three sources. Different regression lines and significantly different mean inhibition zone diameters were found for the three Mueller-Hinton agars. Single zone-diameter breakpoints of either 13 or 16 mm for the standardized disk agar-diffusion test produced unacceptable rates of false-sensitive and false-resistant interpretations. When error rates were limited by using zone-diameter breakpoints determined by the method of error rate-bound analysis, the percentage of indeterminate interpretations became so large as to make the standardized disk agar-diffusion test impractical. It is concluded that the standardized disk agar-diffusion test should not be used for testing susceptibility of the fluorescent pseudomonads to gentamicin, and presumably other aminoglycosides.

Agar↗