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Biomedical subjects

D E Healing

Publications and source records attributed to D E Healing.

15 recordsLinked to original sources

Improved recovery of antibiotic-stressed microorganisms on inclusion of saponin in aerobic blood culture media.

The recovery rates and times to detection of microorganisms isolated from two similar blood culture media, one containing saponin, were compared. A total of 2117 blood cultures were analysed in a prototype automated blood culture system. Significantly more gram-positive organisms (P<0.05) and gram-negative organisms (P<0.05), including Enterobacteriaceae (P<0.05) were recovered from the lytic medium. Average time to detection in the lytic medium was 15.8 h, compared to 22.7 h in the other medium (P<0.001). The improved recovery of microorganisms was most pronounced in blood samples obtained from patients being treated with antibiotics at the time of venesection. In vitro experiments on antibiotic affected bacteria confirmed the protective effect of saponin.

Anti-Bacterial Agents↗

Use of prototype automated blood culture system and gas-liquid chromatography for the analysis of continuous ambulatory peritoneal dialysis associated infection.

AIMS: (1) To compare the recovery of organisms from continuous ambulatory peritoneal dialysis (CAPD) effluent fluid obtained from patients with clinical evidence of peritonitis, with an automated system (AS) and the Septichek blood culture system; (2) to evaluate the times to detection of organisms with the two systems; (3) to identify anaerobes from CAPD samples by extended anaerobic culture and gas-liquid chromatography (GLC). METHODS: 168 CAPD effluent fluid samples were studied, representing 157 episodes of peritonitis in 97 patients. CAPD samples were inoculated into two AS bottles-one anaerobic, one aerobic-and a Septichek bottle; samples were also examined for cell count, Gram stain, and direct culture. Culture bottles were then subcultured onto various media, and any organisms isolated were identified. After routine culture, GLC was performed on culture fluid in the anaerobic AS and Septichek bottles. When volatile fatty acids were detected, the broths were cultured anaerobically on specialised medium for a further five days. RESULTS: 147 organisms were isolated from the 168 samples: 96 (57%) yielded growth of significant organisms by direct culture, as compared to 129 (76.8%) by both AS and Septichek. There was no significant difference in isolation rates between AS and Septichek, but time to detection was more rapid with the AS system (p < 0.002). GLC showed volatile fatty acid in 15 specimens; of these, 14 subsequently grew anaerobic organisms. CONCLUSIONS: AS was comparable to Septichek for numbers of isolations. Speed to detection was faster with the AS, which may be an advantage in management of patients with CAPD peritonitis. GLC showed anaerobes in several cases which would not have been detected without prolonged anaerobic culture; thus anaerobic cultures are recommended for patients who are unresponsive to antimicrobials or who have evidence of bowel perforation.

Bacteria↗

Development of o.a.s.i.s., a new automated blood culture system in which detection is based on measurement of bottle headspace pressure changes.

o.a.s.i.s. (Unipath Ltd., Basingstoke, United Kingdom) is a new automated blood culture system. The metabolism of microorganisms is detected by measuring changes in the pressure of the headspace of blood culture bottles. These changes are measured by monitoring the position of a flexible sealing septum, every 5 min, with a scanning laser sensor. This noninvasive system can detect both gas absorption and production and does not rely solely on measuring increasing carbon dioxide levels. A research prototype instrument was used to carry out an evaluation of the media, the detection system, and its associated detection algorithm. In simulated blood cultures, o.a.s.i.s. supported growth and detected a range of clinical isolates. Times to positivity were significantly shorter in o.a.s.i.s. than in the BACTEC 460 system. Results of a clinical feasibility study, with a manual blood culture system as a control, confirmed that o.a.s.i.s. was able to support the growth and detection of a variety of clinically significant organisms. On the basis of these findings, full-scale comparative clinical trials of o.a.s.i.s. with other automated blood culture systems are warranted.

Adolescent↗

Monitoring of hospital water supplies for Legionella.

In order to determine the value of regular surveillance for Legionella in the prevention of hospital-acquired (nosocomial) legionellosis, water samples were obtained over a three-year period from 17 hospitals located in England and Scotland. Prior to the study, all of the hospitals had in operation defined protocols and maintenance schedules which followed national guidelines for the prevention of legionellosis in health care premises. Six samples, from key locations in the water system of each hospital, were taken at six-monthly intervals. Total viable bacterial count (TVC), coliform count and legionella cultures were performed on all the samples. No coliforms were detected in any of the samples, whereas the TVC was variable. Legionella pneumophila was isolated from both the hot and cold water supplies of two hospitals. The TVC was not related to the isolation of Legionella. Confirmation of the presence of Legionella was subsequently attributed to defects in the equipment and water maintenance programmes. It was concluded that the microbiological examination of water is an effective approach to the audit of the maintenance of hospital water systems in order to prevent legionellosis.

Colony Count, Microbial↗

Evaluation of use of Signal system of blood culture in paediatrics.

A new method of blood culture, the Signal system (Oxoid), was assessed in paediatric practice. Isolation rates of pathogens, frequency of contamination (false positive results), and time taken to detect positive cultures were analysed. Four hundred and seventy nine organisms were isolated from 457 of 3000 cultures collected, of which 283 organisms were considered to be clinically important. The overall rate of positive cultures was 15.2%, and clinically important organisms were isolated from 9.1%, giving an overall contamination rate of 6.1%. The rate of contamination with Gram positive bacilli was 1.1% and coagulase negative staphylococci 4.2%. Over 51.6% of all isolates were detected within 24 hours, 81% within 48 hours, and 86% within three days: 91.1% of clinically important organisms were isolated within three days. Unimportant organisms tended to give a delayed signal, although this sometimes occurred with Candida spp, Klebsiella spp, Pseudomonas spp and a small number of other such organisms. Four hundred and forty nine of the 457 positive cultures gave a visible signal. Six of seven isolates of Haemophilus influenzae failed to give a signal, as did two coagulase negative staphylococci. The Signal system is a convenient and cost effective method of blood culture.

Adolescent↗

Single dose pharmacokinetics of trimethoprim.

Single oral dose trimethoprim pharmacokinetics were determined in 18 children aged 3 months to 13 years. Trimethoprim suspension was rapidly absorbed and quickly and widely distributed. The mean clearance was considerably faster and the elimination half life considerably shorter than values reported in adults. Only one third of the administered drug dose was recovered from the urine within 24 hours which is considerably less than in adults, suggesting that children may metabolise a greater proportion of the dose given. Urine trimethoprim concentrations greatly in excess of minimum inhibitory concentrations for common pathogens were rapidly achieved and sustained for at least 16 hours.

Adolescent↗

Gentamicin and tobramycin compared in the treatment of mucoid pseudomonas lung infections in cystic fibrosis.

18 children with cystic fibrosis and mucoid pseudomonas lung infection were treated with courses either of gentamicin plus carbenicillin, or tobramycin plus carbenicillin, with 2 children each receiving two courses. 10 courses of gentamicin at a dose of 9 mg/kg per day plus carbenicillin at 800 mg/kg per day, and 10 courses of tobramycin at 9 mg/kg per day plus carbenicillin at 800 mg/kg per day were given. There was clinical and x-ray improvement in both groups of children, but there was no difference between the therapeutic benefit of either regimen. Pseudomonas aeruginosa was not cultured at the end of treatment after 15 of the 20 courses, but it returned in all but one patient within 3 months. Neither ototoxicity nor renal damage with these high doses of aminoglycoside was detected. P. aeruginosa had not been eliminated when 9 of these patients earlier had received courses of gentamicin in a dose of 6 mg/kg per day plus carbenicillin at 800 mg/kg per day. The results show that P. aeruginosa can successfully be eliminated or suppressed with high-dose aminoglycoside plus carbenicillin, but such elimination is usually short lived.

Adolescent↗

An outbreak of infection caused by a gentamicin-resistant Staphylococcus aureus.

An outbreak of infection caused by a strain of Staphylococcus aureus resistant to gentamicin and tobramycin and other antibiotics occurred in two wards in a hospital. Eight patients were colonized, of whom six had clinical infections. Previous administration of gentamicin appeared to predispose the patients to infection with the strain. Restriction of the use of gentamicin and tobramycin is essential to preserve their value in serious infections.

Anti-Bacterial Agents↗

Blood for culture.

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Bacteremia↗