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S F Dealler

Publications and source records attributed to S F Dealler.

At least 19 recordsLinked to original sources
PubMed1992

A rapid heat-resistant technique for presumptive identification of Salmonella on desoxycholate-citrate agar.

A caprylate esterase chromogenic test, which was considered to indicate positivity in 5 minutes if a bright colour appeared on the filter paper inoculum site to which one colony had been applied, was used to test 534 Salmonella, 535 other bacteria capable of growth on desoxycholate-citrate agar (DCA), and 517 non-lactose fermenting colonies from stool cultures on DCA. It was found to be 100% sensitive for Salmonella, 99% specific, and more accurate than either direct antiserum agglutination or a urease test in these respects. The test kit could be stored at room temperature.

Agar↗
PubMed1992

Pseudomonas aeruginosa is retained in the bronchi of cystic fibrotics by the increased transepithelial potential.

There is no hypothesis which satisfactorily unifies the abnormal secretions of electrolytes in cystic fibrosis (CF) with the thickened mucus and the retention of Pseudomonas aeruginosa (PA). We have shown that mucus becomes opaque and more viscous adjacent to a positive electrode and that PA derived from CF sputum electrophoreses much faster than control PA. We propose that the increased transepithelial potential in CF respiratory tract acts to thicken mucus polymers thereby increasing its viscosity. We also suggest that as the thicker mucus forms on the epithelial surface bacteria with a high electrophoretic mobility (EM) are drawn into it and are thereby selected.

Bronchi↗
PubMed1992

New rapid identification test for Clostridium difficile.

AIMS: A set of five tests were developed and tested for their ability to confirm the identity of C difficile colonies within 30 minutes. METHODS: The relevant substrates were incorporated into four filter paper squares attached to a plastic carrier (Diffstrip), five enzymes/products (prolyl aminopeptidase, galactosidase, leucine aminopeptidase, acid phosphatase and indole). The strips were inoculated, incubated for 20 minutes, and reagents added. RESULTS: 96.4% (212 of 220) strains of C difficile were immediately differentiated from 51 other Clostridium spp tested. The remaining 3.6% (eight of 220) of C difficile isolates produced a reaction pattern similar to some of the Clostridium sporogenes tested and required additional tests. None of the other Clostridium spp tested produced reaction patterns similar to C difficile. CONCLUSION: The Diffstrip allowed colonies of C difficile to be confirmed within 30 minutes for 96.4% of isolates, with less than 4% requiring any additional tests. No strains of C difficile were misidentified and no strains of other Clostridium spp tested were misidentified as C difficile.

Bacterial Typing Techniques↗
PubMed1992

Escherichia coli: rapid identification by chromogenic tests.

A system has been assessed for the identification of Esch. coli using a rapid triple chromogenic test which relies on the ability of the organism to produce a beta-galactosidase, a beta-glucuronidase, and indole. Coliforms which had been fully identified were tested by this system. Of 512 non-Esch. coli strains there were no false positives, whereas of 514 Esch. coli strains 486 (94.5%) were found to give positive results. Two hundred and twenty-one coliforms that had been isolated from blood cultures were also tested using the colistrip in advance of, or without knowledge of the API 20E result. The test was found to be 100% specific and 94% sensitive for the 105 Esch. coli strains. The test was rapid, simple to perform and economical.

Chromogenic Compounds↗
PubMed1991

Rapid screening of colonies from Listeria selective agar.

A rapid method ('Liststrip', Lab M) of screening aesculin-positive colonies from Oxford selective agar was evaluated. This method relies on the ability of all Listeria spp. to hydrolyse aesculin and to have a rapid phosphatase but neither a pyroglutamic acid beta-naphthylamide amidase nor produce indole. Of 198 Listeria spp., all gave identical results (as above) in 10 min (except four isolates of L. murrayi), whereas of 112 aesculin-positive colonies from Oxford agar that were not Listeria only one gave a similar result. The method was compared with Gram stain and oxidase as a screening procedure. This strip test method is simple enough to be used by relatively unskilled staff and provides a rapid and reliable method to screen colonies from Oxford selective agar.

Bacteriological Techniques↗
PubMed1991

Provisional identification of Haemophilus influenzae from sputum cultures within 1 h by rapid enzyme tests.

Possible Haemophilus influenzae colonies in cultures of sputum samples are currently identified by tests for dependence on X and V factors. This method requires further overnight culture and may give a relatively high number of false negative results. Identification of suspected H. influenzae colonies by a 5-min test for production of indole and beta-galactosidase followed by a 1-h porphyrin test was compared with tests for dependence on X and V factors. A commercially produced form of the rapid tests (Haemstrip, Lab M, Bury, Lancs) was used to test 252 potential haemophilus colonies from cultures of sputum samples on heated blood agar. Colonies that were beta-galactosidase-positive after 5 min were considered to be non-H. influenzae and those that were beta-galactosidase-negative but indole-positive were considered to be H. influenzae. At this stage the test had a sensitivity of 99.4% and a specificity of 90.9%. After 1 h, only colonies that were beta-galactosidase- and porphyrin-negative were considered to be H. influenzae, the sensitivity was then 99.5% and the specificity 100%. Similar results were found with colonies from sputum cultures on selective heated blood agar containing bacitracin. The X and V dependence and Haemstrip results were in 97.6% agreement in a double blind test. Of 100 non-haemophilus colonies tested by Haemstrip, two pseudomonads could have been identified as H. influenzae by this method. The high positive predictive value of Haemstrip results depends partly on the initial recognition of potential haemophilus colonies.

Bacteriological Techniques↗
PubMed1991

Candida albicans colony identification in 5 minutes in a general microbiology laboratory.

A total of 381 fully identified yeast isolates were tested by the germ tube (GT) and Albistrip (Lab M Ltd., Bury, United Kingdom) methods, and the results were compared. As a test system for the identification of Candida albicans, the Albistrip showed two false-positive and two false-negative results, whereas the GT showed seven false-negative and no false-positive results. With the same methods, 736 yeast isolates from clinical samples were tested in a laboratory that did not specialize in mycology. In this second experiment, when the results of the tests disagreed, further identification was carried out with the API 20C Yeast Identification System (API-Biomerieux Ltd., Vercieu, France). When the statistics of the first experiment were used to justify the results, this second experiment showed the Albistrip to be 98% sensitive and 98% specific, whereas the GT was 98% sensitive and 95% specific.

Candida albicans↗
PubMed1991

Identification of Neisseria gonorrhoeae using the Neisstrip rapid enzyme detection test.

A rapid enzyme activity strip test (Neisstrip, Lab M Ltd, Bury) was compared retrospectively with Phadebact Monoclonal GC coagglutination (Pharmacia Diagnostics, Uppsala, Sweden), cystine trypticase agar sugar utilisation (CTA), and Gonochek II (J W Turner, Liverpool) enzyme methods for identification of 95 Neisseria spp and related species. These had been previously identified using standard methods and included 29 that had given aberrant results. Neisstrip identified correctly all but two, including nine incorrectly identified by Phadebact and 18 erroneously identified using CTA sugars. Results were similar to those obtained with Gonochek II. After this a prospective study was performed testing 400 oxidase positive isolates derived from clinical samples cultured on gonococcal selective medium. Two organisms, both Moraxella spp, were incorrectly identified as N gonorrhoeae by the Neisstrip. The superoxol test, when used with either the Phadebact or Neisstrip tests, maintained 100% sensitivity and specificity. The Neisstrip is a rapid, economic test that is accurate and easy to interpret. It may be used alone or in conjunction with a superoxol test or a coagglutination test, which is relatively accurate but more expensive, and found by some technical staff to be more difficult to interpret.

Aminopeptidases↗
PubMed1991

Development of the transdermal potential of human skin.

The development of the transdermal electrical potential (TDP) with postnatal age was studied in neonates born at gestational ages of 25 to 42 wk. The TDP of neonates born at less than 28 wk gestational age was of similar magnitude over the whole skin surface when measured in the first 5 d of life (mean value -5.4 mV; skin surface negative with respect to s.c. tissues). The TDP increased progressively with increasing gestational and postnatal age. The rate of increase of the TDP with postmenstrual age was not accelerated in neonates born prematurely. TDP values of infants born at term were lower than those of adults, but the sites of high and low TDP were similar in both term infants and adults.

Adult↗
PubMed1989

Reliable five-minute test strip method for identification of Streptococcus pyogenes.

A novel and rapid method (Strep Strip, Lab M) for identification of Streptococcus pyogenes was evaluated. The method combines the established test for pyroglutamyl aminopeptidase (PYR) with a rapid chromogenic test for beta-glucosidase on a paper strip. The test was evaluated with 274 clinical isolates and 237 culture collection isolates of beta-haemolytic streptococci. Streptococcus pyogenes was identified with 100% specificity. Six isolates identified as Lancefield group A and which might therefore be assumed to be Streptococcus pyogenes were shown by the test strip method not to be this species. The beta-glucosidase test on the test strip allowed differentiation between enterococci and Streptococcus pyogenes (both PYR positive) in all cases. The test strip method represents an economical and accurate method for identification of Streptococcus pyogenes in clinical material.

Aminopeptidases↗
PubMed1989

Purple urine bags.

Purple urine drainage bags were found in 7 of 71 chronically catheterized elderly women. The purple staining of the bags is due to a violet discoloration (indirubin) of the plastic of the catheter bag and fine blue crystals of indigo in the urine. The colors are formed from the substrate indoxyl sulfate (indican) and all 7 patients had bacteria in the urine that would produce blue colonies on agar enriched with the urine (filter sterilized) of the patients involved. Organisms identified were Providencia or Klebsiella species. Indican excretion was higher in patients with purple urinary catheter bags than in controls.

Aged↗