Biomedical subjects

M J Bale

Publications and source records attributed to M J Bale.

31 records · Page 2Linked to original sources

PubMed1990

Comparative in vitro activity of the new quinolone sparfloxacin (CI-978, AT-4140) against nosocomial gram-negative bloodstream isolates.

The in vitro activity of sparfloxacin (CI-978, AT-4140), a new quinolone which is active against gram-negative and gram-positive bacteria, and nine other broad-spectrum antibiotics was tested against 128 gram-negative nosocomial bloodstream isolates from separate patients. Sparfloxacin and ciprofloxacin were among the most potent antibiotics against Escherichia coli (n = 40), Enterobacter cloacae (n = 18), Klebsiella oxytoca (n = 13), and Klebsiella pneumoniae (n = 19), with MIC90 values of less than or equal to 0.25 microgram/ml. Ciprofloxacin was slightly more potent than sparfloxacin against Serratia marcescens (n = 14), the MIC90 values being 0.25 and 1.0 micrograms/ml respectively, although all strains were susceptible to both agents. Sparfloxacin was slightly less potent than ciprofloxacin against Pseudomonas aeruginosa (n = 24), the MIC90 values being 4.0 and 0.5 micrograms/ml respectively. Overall, the in vitro activity of sparfloxacin compared favorably with that of ciprofloxacin and the other broad spectrum agents tested against nosocomial gram-negative bloodstream isolates.

Amikacin↗

PubMed1988

Prospective evaluation of the Gen-Probe assay for detection of legionellae in respiratory specimens.

A prospective evaluation of a DNA probe assay for detection of Legionella species was performed on 427 consecutive respiratory specimens submitted over an 18-month period. The Gen-Probe assay utilizing both low (greater than or equal to 4.0) and high (greater than 7.0) ratio threshold values was compared to direct fluorescent antibody staining (DFA) as a predictor of isolation of Legionella on culture. The highest sensitivity (63%) was obtained with the lower threshold ratio, but was not significantly different from the result obtained with a threshold ratio of greater than 7.0 (50%, p = 0.722) or DFA results (44%, p = 0.479). The specificity of the DNA probe assay was improved with the high threshold (99%) compared either to the low threshold ratio (95%, p = 0.002) or DFA (97%, p = 0.055). When the DNA probe was compared to DFA and/or Legionella isolation on culture, a significantly lower specificity (97% versus 99%, p = 0.0006) and higher sensitivity (74% versus 37%, p = 0.013) was obtained with a threshold value of greater than or equal to 4.0 than greater than 7.0. Ten of 20 specimens with a DNA probe ratio between 4.0 and 7.0 were DFA positive, although only two were isolated on culture. The DFA assay and both probe threshold ratios have a high negative predictive value when compared to culture. However, only the threshold ratio of greater than 7.0 has a sufficiently high positive predictive value to be useful alone.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA Probes↗

PubMed1988

Novel method for studying plasmid transfer in undisturbed river epilithon.

A method for in situ mating experiments is described which involved overnight incorporation of donors containing the mercury resistance plasmid pQM1 and recipients into the epilithon on separate river stones. The stones were then joined to begin the mating. Transfer frequencies obtained were between 2.2 x 10(-1) and 2.5 x 10(-6) per recipient and appeared to depend on the donor-to-recipient ratio (489/1 to 0.0047/1) and not on the river temperature (12 to 19 degrees C). Controls showed that the low density of donors and recipients at the end of the experiment (3.4 x 10(2) to 7.0 x 10(5) cm-2) did not significantly affect the heterotrophic bacterial count (1.43 x 10(6) to 6.39 x 10(6) cm-2) nor the fluorescent-pseudomonad count (2.3 x 10(4) to 9.33 x 10(4) cm-2).

Bacteria↗

PubMed1988

Transfer and occurrence of large mercury resistance plasmids in river epilithon.

In situ mating experiments were done in the River Taff, South Wales, United Kingdom, by using a natural mercury resistance plasmid (pQM1) isolated from a mixture of epilithic bacteria in vitro. The river temperature from March to November was found to influence transfer frequencies strongly (6.8 x 10 to 1.5 x 10 per recipient). A linear relationship existed between log(10) transfer frequency and river temperature (6 to 21 degrees C), a 2.6 degrees C change in temperature giving a 10-fold change in transfer frequency. In vitro experiments showed that pQM1 transferred most efficiently between fluorescent pseudomonads and that one epilithic isolate (Pseudomonas fluorescens) was an efficient donor in situ. Experiments with a P. putida recipient showed that intact epilithic bacterial communities could transfer mercury resistance plasmids in situ at frequencies of up to 3.75 x 10 per recipient. Nineteen of the large (>250-kilobase) plasmids isolated by transfer into P. putida were studied in detail and grouped into seven types by restriction digests. Mercury resistance and UV resistance were found to be common linked phenotypes in 19 of the 23 plasmids tested.

Journal Article↗

PubMed1987

Plasmid transfer between strains of Pseudomonas aeruginosa on membrane filters attached to river stones.

A naturally occurring mercury-resistance, conjugative plasmid, designated pQM1, was isolated from a bacterial population on the surface of stones from a river using Pseudomonas aeruginosa as a recipient. This was a narrow-host-range plasmid [IncP-13; 165 MDa; Tra+, Hgr, fluorescein mercuric acetater, merbrominr, Phi(E79), UVr] confined to some Pseudomonas spp. It was used to demonstrate transfer between bacteria on stones in laboratory microcosm experiments and in situ. Transfer occurred (3.3 X 10(-1) to 6.8 X 10(-9) per recipient) at all the temperatures used (6-20 degrees C), although frequencies were lower in the cold. Nutrient status also affected transfer frequency, rich conditions promoting transfer. The presence of competing bacteria in the natural epilithon lowered transfer frequencies, but when unscrubbed stones were heat treated, transfer was enhanced, perhaps because of nutrient release from the heated epilithon.

Fresh Water↗

PubMed1986

Usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci.

The usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci and its implications for therapy were examined. Hospital records were reviewed for 59 patients from each of whom more than one isolate of coagulase-negative staphylococci was obtained. In patients with a prosthetic device, 81% of 59 infectious episodes were due to a slime-positive coagulase-negative staphylococci. In contrast, 22 noninfectious episodes (in which the organisms were contaminants) were equally distributed between episodes due to slime-positive or slime-negative isolates (P = .005). Only 32% of infections caused by slime-positive organisms, in contrast to 100% of infections caused by slime-negative organisms, were improved by treatment with antibiotics alone (P = .02). Prosthetic device removal in addition to antibiotic treatment significantly improved the outcome in patients with infections due to slime-positive organisms when compared with treatment with antibiotics alone (93% vs. 32% improvement; P = .00025).

Anti-Bacterial Agents↗

PubMed1986

An accurate method for estimating sizes of small and large plasmids and DNA fragments by gel electrophoresis.

Several regression methods were tested for estimating the sizes of a wide range of plasmids (1.37-312 MDa) and restriction fragments (2.2-14.2 MDa) by agarose gel electrophoresis. The most accurate and least variable method was the multiple regression of log10 molecular size against log10 relative mobility and the reciprocal square root of the relative mobility. This method gave a good fit to all the data with low percentage errors of the molecular size estimates (less than or equal to 3.0 +/- 1.5%). It is suggested that with this method the molecular size of unknown plasmids can be accurately estimated using the plasmids from Escherichia coli V517 and E. coli IR713 as standards.

Bacteriophage lambda↗

PubMed1986

Comparison of the Quantum II Bacterial Identification System and the AutoMicrobic System for the identification of gram-negative bacilli.

The Quantum II Bacterial Identification System (BID; Abbott Laboratories) is a microprocessor-based spectrophotometric system for identification within 4 to 5 h of both enteric and nonenteric gram-negative bacilli. We compared the BID with the AutoMicrobic System (AMS; Vitek Systems, Inc.), using the most recent gram-negative identification card and software (AMS-GNI), for the identification of 501 clinical isolates of gram-negative bacilli, including 382 belonging to the Enterobacteriaceae and 119 nonenteric organisms. The API 20E (Analytab Products) was used as the reference system. The BID correctly identified 375 (98.2%) of the Enterobacteriaceae isolates and 111 (93.2%) of the nonenteric isolates; the AMS-GNI correctly identified 374 (97.9%) and 115 (96.6%) isolates, respectively. The BID identified all isolates within 5 h, whereas the AMS-GNI identified only 35% within this time period. The BID performed comparably to the AMS-GNI for the identification of most gram-negative bacilli. Simplicity, speed, and relatively low reagent cost make the BID a competitive system for many clinical laboratories.

Acinetobacter↗

PubMed1985

The spot indole test for identification of swarming Proteus.

The authors evaluated the use of the spot indole test for rapid speciation of swarming Proteus from the primary isolation plate. One hundred seventy-two consecutive isolates of swarming Proteus were studied, 163 Proteus mirabilis and nine Proteus vulgaris. One hundred fifty-six isolates (95.7%) of Proteus mirabilis gave a negative spot indole. Seven (4.3%) gave a positive spot indole test, but all seven isolates were from cultures in which other indole-producing organisms also were present. If only isolates representing single gram-negative strains in the specimens were tested, the predictive value was greater than 99%. Eight of the nine (88.9%) Proteus vulgaris isolates gave a positive spot indole test; one (11.1%) gave a negative result. This isolate also failed to produce indole by conventional methods but was ornithine decarboxylase negative, and additional biochemical testing was consistent with the Proteus vulgaris identification. All Proteus vulgaris isolates were resistant to ampicillin, and 94.2% of the Proteus mirabilis tested were ampicillin susceptible. The spot indole test is a rapid, accurate, simple, and cost-effective means of speciating swarming Proteus strains isolated as the only gram-negative bacilli in a specimen. The spot indole test should be used in conjunction with an ampicillin susceptibility test result or other confirmatory test information if other gram-negative bacilli are present in the culture.

Ampicillin↗

PubMed1984

Use of and cost savings with morphologic criteria and the spot indole test as a routine means of identification of Escherichia coli.

The use of primary isolation plate colonial morphologic criteria (CMC) of a flat, nonmucoid, lactose-fermenting, gram-negative rod on MacConkey agar and the spot indole (SI) test from the sheep blood agar plate was evaluated as a means for identification of Escherichia coli in comparison to kit (Micro-ID, API-20E) and conventional biochemical testing. In this preliminary phase of comparison of accuracy, 427 isolates of E. coli (69.8%) from a total of 612 isolates of lactose-fermenting gram-negative rods were evaluated. Of these E. coli isolates, 357 (83.6%) fit the CMC and were SI positive; 3 (less than 1% error rate) were not E. coli. In the second phase of the evaluation, using CMC and SI alone as a means for identification of E. coli, 472 (57.6%) E. coli isolates from a total of 820 Enterobacteriaceae isolates were assessed. Of these E. coli isolates, 326 could be identified using only CMC and SI (69.1% of the E. coli isolates and 39.8% of all Enterobacteriaceae isolates); 146 (30.9%) required additional biochemical testing because of atypical colonial morphology, because of the investigator's inability to differentiate colony types on both media or lack of isolated colonies on either of the two required media, or because as isolates from sterile body sites they were processed directly to Micro-ID kits. A minimum of 40% savings on Enterobacteriaceae identification schemes without compromising accuracy was calculated. As of November 1983, a direct (labor and materials) cost savings of approximately +200.80 per 100 Enterobacteriaceae identifications was projected.

Agar↗

PubMed1981

Identification of Pseudomonas aeruginosa by pyocyanin production on Tech agar.

Pseudomonas aeruginosa is the only gram-negative bacillus capable of producing the very distinctive water-soluble pigment pyocyanin. We evaluated the reliability of this characteristic as a unique test for the identification of this organism by using Tech agar (BBL Microbiology Systems, Cockeysville, Md.) medium. A retrospective and prospective analysis was performed with a total of 835 strains of P. aeruginosa; 818 (98%) produced pigment within 48 h of incubation, and 96% of those which produced pigment were positive after overnight incubation. Seventeen strains (2.0%) failed to produce pigment; 15 were mucoid strains from patients with cystic fibrosis. Tech agar is an effective, simple, and inexpensive medium for P. aeruginosa identification and may be used as a unique test for all potential P. aeruginosa isolates (beta hemolytic on blood agar; lactose-negative, oxidase-positive colonies). Nonpigmented mucoid strains, as well as other nonpigmented organisms, will require additional testing to ensure proper identification.

Bacteriological Techniques↗

PubMed1981

Evidence against the practicality and cost-effectiveness of a gram-positive coccal selective plate for routine urine cultures.

A total of 899 urine cultures were evaluated to assess the need for and cost-effectiveness of using a gram-positive coccal selective plate in the initial plating of urine cultures. Of these cultures, 437 were examined retrospectively and 462 were examined prospectively. Urines were quantitatively plated to three media: sheep blood sugar, MacConkey agar, and phenyl ethyl alcohol agar. Of all urine samples in both studies, 52% yielded no growth on any of the three media. Of all 899 urine cultures, there were only 5 cultures (less than 1%) in which a significant count of a gram-positive organism was detected only on the phenyl ethyl alcohol agar plate and not recoverable on the sheep blood agar plate. In each of these five instances, the need for the use of the selective plate occurred when a Proteus mirabilis strain swarmed over an enterococcus. The inclusion of a selective gram-positive coccal medium for initial plating of urine cultures is unnecessary and not cost-effective. When Proteus swarms on sheep blood agar, a sweep should be made with an inoculating loop from the sheep blood agar and streaked to phenyl ethyl alcohol agar or a similar gram-positive coccal selective medium.

Bacterial Infections↗

PubMed1981

Time-motion and cost comparison study of micro-ID, API 20E, and conventional biochemical testing in identification of Enterobacteriaceae.

A total of 730 Enterobacteriaceae strains isolated from 567 cultures were evaluated by a rapid kit method (Micro-ID; General Diagnostics, Morris Plains, N.J.; 4 h), an overnight incubation kit method (API 20E; Analytab Products, Plainview, N.Y.), and conventional biochemical test methodology (mostly overnight incubation and some rapid methods) to compare the amount of laboratory effort required, timing, and cost parameters. We assessed the amount of technologist time expended, the time sequence of culture reporting to physicians, the number of isolates requiring repeat testing or additional biochemical testing, the number of cultures held due to the need for identification of other organisms, the cost of total work-up, etc. Cultures evaluated included urines, respiratory cultures, wound cultures, body fluids, genital cultures, and cultures from miscellaneous categories. A total of 64% of the Enterobacteriaceae strains processed by the Micro-ID method could be identified within 24 h of receipt of the specimens in the clinical laboratories, in contrast to the need for an additional day required by the API or conventional biochemical methods. The Micro-ID method also required less technologist time (4.5 min) for set-up and interpretation than did either the API method (6 min) or conventional methods (7 min). Total direct costs (June 1981) per organism identified were: Micro-ID, $4.30; API 20E, $4.96; conventional biochemicals with commercially prepared media, $5.66. An estimate of 80% technologist time efficiency was made in all procedures.

Bacteriological Techniques↗