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Biomedical subjects

P R Chadwick

Publications and source records attributed to P R Chadwick.

At least 37 records · Page 2Linked to original sources

Screening for bacterial vaginosis: a novel application of artificial nose technology.

The AromaScan system was used to analyse vaginal swabs from 68 women attending a genitourinary clinic. Using clinical criteria, subjects were assessed for bacterial vaginosis. After training the AromaScan system to recognise patterns generated from four patients with and four patients without bacterial vaginosis, 16 of the 17 (94%) remaining subjects were correctly identified as having the condition. The positive predictive value of the test was 61.5%. These results indicate that the AromaScan technology may be of value as a screening test for bacterial vaginosis.

Clinical Laboratory Techniques↗

Monitoring wound healing by odour.

A pilot study using electronic aroma detection was performed over a six-month period to assess the aroma of chronic non-healing venous leg ulcers and the effect of appropriate antibiotic therapy on modification of the aroma. Deep infection with pathogenic organisms was found on biopsy culture in 13 out of 15 patients. Odour analysis was performed at weekly intervals on the ulcer dressings using an AromaScan instrument. Data points on the aroma maps moved from their pre-treatment presentation. Alterations in aroma data correlated well with the progress of the ulcers. Aroma analysis is shown to be a potential tool in monitoring the progress towards healing of chronic venous ulcers.

Aged↗

Epidemiology of an outbreak due to glycopeptide-resistant Enterococcus faecium on a leukaemia unit.

The clinical and molecular epidemiology of two clusters of colonization and infection of patients by glycopeptide-resistant enterococci (GRE) on a leukaemia and bone marrow transplantation unit was studied over a two-and-a half-year period. Thirty-five patients became colonized, of whom six developed clinical infections. Of the 53 isolates of GRE, 49 were Enterococcus faecium, multiply-resistant to vancomycin and ampicillin. DNA fingerprinting of 48 E. faecium isolates by pulsed-field gel electrophoresis identified six DNA types. One strain of VanB phenotype E. faecium predominated during the initial outbreak, and an unrelated strain of the VanA phenotype was present in a second cluster. Environmental and patient isolates of E. faecium were indistinguishable by DNA typing. The VanA phenotype enterococci probably arose by transfer from the renal ward at a nearby hospital, and a patient with persistent diarrhoea may have contributed to contamination and cross-infection. GRE may cause significant infections in immunocompromised patients, and are readily transmitted between them. GRE were controlled, but not eradicated on the unit; infection control measures included improved environmental cleaning and modification of antibiotic use. In order to control GRE, it is necessary to educate healthcare workers and implement the traditional, effective values of good personal hygiene and environmental cleanliness.

Adult↗

Heat tolerance of vancomycin resistant Enterococcus faecium.

The heat tolerance of 27 Enterococcus faecium isolates in water was studied. Stationary phase cultures including vancomycin resistant and sensitive clinical and food isolates were exposed to heat at 60 degrees, 65 degrees, 71 degrees, and 80 degrees C for one, three, 10, and 30 minutes and the log10 reductions in bacterial counts were determined. Exposure at 71 degrees and 80 degrees C resulted in > 6 log10 reduction in viable counts for all isolates. Seven (24%) isolates survived (< 5 log10 reduction) heat at 65 degrees C for 10 minutes. The E faecium isolates were more resistant to heat than the two E faecalis reference strains. No differences in heat tolerance were observed between vancomycin sensitive and resistant strains or between isolates of human or food origin.

Drug Resistance, Microbial↗

Haemophilus paraphrophilus infection: a pitfall in laboratory diagnosis.

Many clinical laboratories have difficulty in identifying a group of organisms which are catalase negative, oxidase positive, Gram negative rods. We describe a case of purulent sacroiliitis due to Haemophilus paraphrophilus where the organism was initially misidentified as Eikenella corrodens leading to inappropriate antimicrobial chemotherapy. We review the strains of H. paraphrophilus and E. corrodens that were identified by the National Collection of Type Cultures over the last ten years. Only 21 of 100 strains identified as E. corrodens were submitted as E. corrodens. Seven strains submitted as possible E. corrodens were identified as H. paraphrophilus. Several different species of Gram negative rods may produce pitting on agar and this seems to be poorly recognised. However, further tests are available to facilitate correct identification of these strains.

Adult↗

Neomycin blood agar as a selective medium for vancomycin resistant Enterococcus faecium.

Neomycin blood agar is commonly used as a selective medium for the isolation of vancomycin resistant enterococci from faeces; however, not all isolates are recovered using this medium, perhaps because the neomycin concentrations are too high. To test this hypothesis, the neomycin minimum inhibitory concentration (MIC) was determined for 27 vancomycin resistant Enterococcus faecium isolates, 14 from patients with leukaemia and 13 from patients on the renal unit. A further eight isolates that had been recovered from the faeces of patients on the renal unit on neomycin agar were also studied. Eleven of the 14 isolates from the patients with leukaemia showed equal recovery on neomycin agar and blood agar and had MICs > 64 mg/l. In three other isolates there was a 4log10 reduction in recovery on neomycin agar and the MIC was 8 mg/l. Two of the non-selected isolates from the renal unit were recovered equally on the two media, the other 11 isolates showed a 4-5 log10 reduction in recovery. All eight faecal isolates recovered from patients on the renal unit on neomycin agar were highly resistant to neomycin (MIC > 64 mg/l). Comparative studies of screening media are urgently needed as vancomycin resistant enterococci become more prevalent nosocomial pathogens.

Agar↗

Leg ulcer odour detection identifies beta-haemolytic streptococcal infection.

beta-Haemolytic streptococci were identified in bacteriological cultures from 14 of 24 chronic venous leg ulcers in 21 patients. Multi-element odour detection (MEOD) analysis demonstrated a significant difference in odour in those ulcers from which beta-haemolytic streptococci were isolated (p < 0.01). MEOD has potential to detect pathogenic organisms instantaneously in the clinical setting.

Chronic Disease↗

Transmission of a small round structured virus by vomiting during a hospital outbreak of gastroenteritis.

An outbreak of gastroenteritis due to a small round structured virus (SRSV) (Norwalk-like virus) occurred in an elderly care unit, affecting a total of 126 patients and staff. The outbreak caused major disruption to the provision of health care services by the unit over a 3-week period. Following the outbreak a study was undertaken to explore risk factors for acquisition of SRSV infection by health care workers on the unit. Exposure to patients nearby who were vomiting and the number of close contacts with ill patients were significantly related to the risk of developing gastroenteritis (P < 0.05). No significant increase in risk of developing gastroenteritis was found in nurses who cleaned vomit or faeces from affected patients. The findings suggest that aerosolization of vomit was of major importance in transmission of infection during the outbreak; the implications for infection control are discussed.

Caliciviridae Infections↗