Biomedical subjects

S T Aspinall

Publications and source records attributed to S T Aspinall.

4 recordsLinked to original sources

PubMed1992

Improved isolation of salmonellae from faeces using a semisolid Rappaport-Vassiliadis medium.

A modified semisolid Rappaport-Vassiliadis (MSRV) enrichment medium was evaluated as an alternative to Rappaport-Vassiliadis (RV) broth for culture of salmonellae from faeces. Faeces from 1544 subjects were cultured using MSRV medium, selective agars, and RV and selenite F enrichment broths. Of the 183 strains of Salmonella spp. isolated, 88% were recovered on MSRV medium, whilst only 59% were recovered using RV broth. When MSRV medium was combined with direct culture and selenite enrichment, 98.9% of salmonellae were recovered. The MSRV culture was found to be easy to read, and in most cases confirmation of organisms as Salmonella spp. could be made 24 hours after receipt of the faecal specimen.

Agar↗

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

New selective medium for isolating Clostridium difficile from faeces.

AIMS: To compare CCFA (cycloserine, cefoxitin fructose agar) with a new selective medium CDMN (containing cysteine hydrochloride, norfloxacin, and moxalactam) for the isolation of Clostridium difficile after direct faecal culture. METHODS: The minimum inhibitory concentration (MIC) of norfloxacin was determined for 64 strains of C difficile, 17 strains of other Clostridium sp, and 66 various isolates of faecal origin, together with MIC determinations of moxalactam against the 81 strains of Clostridium sp and 15 isolates of Bacteroides sp. Using C difficile agar base with 0.5 g/l of cysteine hydrochloride, norfloxacin and moxalactam were incorporated into the medium and compared with CCFA for the isolation of C difficile after direct faecal culture. RESULTS: Norfloxacin (12 mg/l) inhibited the growth of enterobacteriaceae and faecal streptococci; moxalactam (32 mg/l) inhibited the growth of most strains of Bacteroides sp tested, together with Clostridium sp other than C difficile. Using the antibiotics in combination (CDMN), the growth and colonial morphology of 64 strains of C difficile were unaffected. When CDMN medium was compared with CCFA for the isolation of C difficile from 832 faeces from inpatients with diarrhoea, the CDMN agar isolated 20% more strains and reduced the number of contaminating colonies by 30%. CONCLUSIONS: CDMN both improves the isolation rate of C difficile from faecal specimens and reduces the growth of other organisms compared with CCFA.

Clostridioides difficile↗

PubMed1989

Two sources of contamination of a hydrotherapy pool by environmental organisms.

As a result of occasional water discolouration, the hydrotherapy pool of a large teaching hospital was monitored for free and combined chlorine, alkalinity, calcium hardness, total dissolved solids and cyanuric acid levels together with bacteriological analysis. The hose pipe supplying the pool and the dual water pumps were also examined as potential sources of bacterial contamination. The pool water yielded high counts of Pseudomonas vesicularis, Pseudomonas aeruginosa, and CDC Group IV C2, even in the presence of adequate levels of free chlorine. This was found to be due to high concentrations of cyanuric acid which resulted in a 'chlorine lock'. The source of the P. vesicularis and CDC Group IV C2 was found to be the pool hose and this problem was alleviated by flushing it with water each day before use. The source of the P. aeruginosa was the pool pumps, and was eradicated by regularly shock dosing them with 6-8 ppm of free chlorine.

Bacterial Typing Techniques↗