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Biomedical subjects

R E Warren

Publications and source records attributed to R E Warren.

At least 73 records · Page 4Linked to original sources
PubMed1986

Portable lung ventilators: the potential risk from bacterial colonisation.

Seven portable lung ventilators were investigated to assess the risk of bacterial colonization of the ventilator valve. One valve was deliberately contaminated with Serratia marcescens and the survival of organisms within the valve studied. Periods of colonization by Acinetobacter were found in all the hospital ventilators studied but none of those from the ambulance service. The potential risk to the patient from this organism is discussed and the importance of adequate storage and regular cleaning of the ventilator valve emphasised. Since humidification of the patients inspired gas during transfer is desirable, the use of a combined heat and moisture exchanger and microbiological filter would appear advisable.

Acinetobacter↗
PubMed1986

Removal of bacterial contaminants from semen for in vitro fertilization or artificial insemination by the use of buoyant density centrifugation.

Buoyant density centrifugation of semen produces the accumulation of populations of highly motile, morphologically normal spermatozoa in the lowermost 1 ml of Percoll (Pharmacia Fine Chemicals AB, Uppsala, Sweden) density gradients. In addition, the majority of bacteria present in semen are retained in the seminal plasma at the top of the gradients. Of 40 semen samples examined, 37 contained detectable bacteria, but after buoyant density centrifugation, the spermatozoal populations collected from the lowermost 1 ml of the Percoll columns were found to contain few or no bacteria. When preparations were collected using sterile technique (by boring a hole through the bottom of the centrifuge tube), 14 of the 20 preparations were found to be bacteria-free. When preparations were collected by passing a spinal needle from the surface through the seminal plasma to the bottom of the centrifuge tube, the sterility of the final spermatozoa preparations was not maintained, with only 5 of the 20 samples completely free of bacteria. The residual bacterial contamination of the remaining 15 samples was, however, very low (less than 5 colonies after a 48-hour culture period).

Bacteria↗
PubMed1985

Clostridium difficile in haematological malignancy.

Twenty patients with haematological malignancies who developed Clostridium difficile bowel infection or colonisation are described. All isolates of C difficile were toxigenic in vitro and faecal cytotoxin (toxin B) was detected in 20/26 episodes. Ten of 20 episodes with detectable faecal cytotoxin were associated with typical antibiotic associated diarrhoea. In the other 10 episodes (nine patients), there was a severe unusual illness which was associated with detection of C difficile. The unusual features of the illness were pronounced jaundice (total bilirubin greater than or equal to 44 mumol/l), abdominal pain and distension, and initial constipation followed either by diarrhoea or by large bowel stasis. Four of these patients died within seven days. Bacteraemia was often a presenting feature in neutropenic patients subsequently shown to have C difficile. This was not the case in non-neutropenic patients. Bacteraemia was commonly polymicrobial and in two cases C difficile was isolated from blood culture. The clinical implications of recognition of this atypical C difficile associated syndrome are discussed.

Adolescent↗
PubMed1985

IgG enzyme linked immunosorbent assay for diagnosis of invasive aspergillosis: retrospective study over 15 years of transplant recipients.

Four commercially available Aspergillus fumigatus antigens were compared in an IgG enzyme linked immunosorbent assay by testing multiple sera from 19 patients who had received renal and hepatic allografts and who had histologically confirmed invasive aspergillosis. Raised antibody levels were found in 16 of the 19 patients. More antibody responses were detected by culture filtrate antigens, but somatic antigens often detected antibodies sooner. When antibodies to Aspergillus antigens were present before transplantation the onset of fatal disseminated infection was earlier. Antibody levels often fell to within the normal range, even in cases of fulminant disseminated infection. Repeated serology was essential for detection of an antibody response.

Antibodies, Fungal↗
PubMed1984

Monocyte procoagulant activity in Whipple's disease.

We have studied the expression of procoagulant activity by the circulating mononuclear cells of four patients with Whipple's disease. There was a spontaneous expression of procoagulant activity in two patients with active untreated Whipple's disease. This activity was shown to originate in the monocyte fraction of the mononuclear cells and was demonstrated to cleave prothrombin directly. This prothrombinase activity was not Factor Xa, because it was not neutralized by anti-Factor X serum and was not inhibited by an established panel of Factor Xa inhibitors. The prothrombinase activity was not expressed by the monocytes of these patients following 8 weeks of antibiotic therapy, by which time the patients' symptoms resolved, and was not found in two patients previously treated for Whipple's disease who were in clinical remission or in normal subjects. Serial studies in one patient with active disease showed that monocytes failed to express increased prothrombinase within 2 weeks of antibiotic therapy. A second procoagulant activity was produced in response to endotoxin (LPS) by cells from controls and patients with Whipple's disease and was identified as thromboplastin. These observations suggest that circulating monocytes of patients with active Whipple's disease are endogenously stimulated to express prothrombinase activity, which may contribute, at least in part, to the pathophysiology of this condition.

Adult↗
PubMed1984

A review of Haemophilus influenzae infections in Cambridge 1975-1981.

Invasive Haemophilus influenzae infections diagnosed in Cambridge between January 1975 and December 1981 are reviewed. Altogether, 81 sites in 77 patients were infected. Of these patients, 41 had meningitis, 20 epiglottitis, 8 bone or joint infections (2 with concurrent meningitis), 4 cellulitis, 5 pneumonia (2 with concurrent epiglottitis) and 3 septicaemia in the absence of documented localised infection. Most patients (88%) were children less than 5 years of age. Only 8 adults with such infections were identified. Of these, 6 had an identifiable predisposing condition. The incidence of meningitis was 18 cases per 100 000 children less than 5 years of age. There were 3 deaths. Of the strains of H. influenzae isolated, 16% were ampicillin-resistant. The unusual age-specific incidence of epiglottitis and the incidence of deafness after meningitis are emphasised.

Adult↗
PubMed1984

Automated detection of micro-organisms in blood cultures by means of the Malthus Microbiological Growth Analyser.

A prototype Malthus Microbiological Growth Analyser was compared with conventional methods for examining blood cultures in a trial of 651 cultures mostly from patients with haematological malignancy or undergoing haemodialysis or renal transplantation. Of 100 significantly positive cultures, organisms from 82 grew in the conventional aerobic (+ CO2) bottle, 78 in the conventional anaerobic bottle and 71 in the Malthus bottle. The differences were not statistically significant (p greater than 0.05). The Malthus system detected 83.6% of significantly positive cultures earlier than the comparable conventional bottles while 7.3% positive cultures were detected earlier by the conventional system. When use of the Malthus system was restricted to the hours of 09.00 to 17.30 daily 27.3% positive cultures were detected earlier by the Malthus system and 16.4% were detected earlier by the conventional system. One of the organisms which grew in the Malthus bottle, a contaminating Staphylococcus epidermidis, was not detected by the Malthus system. Instability of electrodes resulted in 26.9% false positive cultures with the prototype Malthus system. Contamination rates in both the Malthus and conventional anaerobic bottles were lower than in the aerobic bottles.

Bacteria↗
PubMed1984

Neutropenic enterocolitis due to Clostridium septicum infection.

Three cases of neutropenic enterocolitis are described. This unusual condition occurs almost exclusively in neutropenic patients and has a fulminating course which is almost invariably fatal without surgical intervention. The lesion is centered on the caecum and hitherto its pathogenesis has been unclear, partly because most studies have been performed on material obtained at necropsy. In these three patients, all of whom were treated surgically, Clostridium septicum was identified by specific immunofluorescence in the bowel wall of the resected specimens. Two patients also had C septicum septicaemia. Various forms of mucosal damage can be identified which predispose towards invasion of the bowel wall by this organism. These cases provide further confirmation of a primary role for C septicum in the pathogenesis of neutropenic enterocolitis.

Adolescent↗
PubMed1984

Rectal organ culture as a model for the investigation of bacterial adhesion and invasion.

A system was developed for the in vitro culture of human rectal mucosa. Its viability was proved by histological appearances and by metabolic studies. Biopsy samples were cultured in the presence of appropriate bacteria isolated from the faeces of patients with ulcerative colitis or with dysenteric illnesses. Attempts to show adhesion of bacteria to the mucosa or invasion of the cultured tissue failed. Problems with the use of this model are discussed.

Adhesiveness↗
PubMed1983

Vertebral osteomyelitis due to coccobacilli of the HB group.

Three cases of pyogenic vertebral osteomyelitis occurred in which unusual, fastidious, Gram negative coccobacilli belonging to the "HB" group were isolated. The organisms were Haemophilus aphrophilus in case 1, intermediate between H aphrophilus and Actinobacillus actinomycetemcomitans in case 2, and Eikenella corrodens in case 3. All HB bacteria are sensitive to a wide range of antibiotics.

Actinobacillus↗