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Biomedical subjects

M Farrington

Publications and source records attributed to M Farrington.

At least 37 records · Page 2Linked to original sources
PubMed1997

Dispose of disposables?

We investigated the implications of a change from disposable to regular crockery and cutlery, and the installation of a dishwasher on a 12-bedded-infectious diseases ward. A limited microbiological study of used disposable cutlery revealed contamination by methicillin-resistant Staphylococcus aureus of one utensil out of 12. Changing to conventional utensils could be recommended if a dishwasher meeting DHSS requirements was installed and safe working practices introduced.

Cooking and Eating Utensils↗
PubMed1996

Bone graft contamination from a water de-ionizer during processing in a bone bank.

An organism resembling Burkholderia (formerly Pseudomonas) cepacia was isolated from cultures taken during processing of six bone grafts. The source of the contamination was traced to a water de-ionizer; the problem had begun when procedures had been changed, so that water from the de-ionizer had been used without sterilization. Cultures of bone for grafting not only protect recipients from infection, but act also as useful controls for processes involved in bone banking.

Bone Banks↗
PubMed1996

Bacterial contamination of peripheral blood progenitor cells for transplantation.

Peripheral blood progenitor cells (PBPC) were obtained from 128 apheresis harvests on 64 patients and were tested in duplicate for microbiological contamination (1) after collection and (2) after thawing, following processing and cryopreservation. In this study we have attempted to improve the monitoring of contamination in peripheral blood progenitor cell collections by identifying exogenous contamination that probably originated from the testing laboratory and is therefore not clinically significant. We found no contamination in 82% of harvests, 1.6% of harvests to be significantly contaminated and organisms were isolated from 16.4% that were assessed as clinically nonsignificant. Our experience indicates that the choice of microbiological methods will influence the results and their clinical relevance. No samples were positive by direct culture. We recommend that sampling should be performed at more than one stage during the procedure and that initially only the post-thaw samples be analysed. Testing should be performed by enrichment culture in duplicate only and if positive to aid interpretation the post-collection sample should then be cultured. No patient given nonsignificantly contaminated graft without antibiotic cover suffered infection from the identified organism. The incidence of significant contamination was low and we recommend that in these cases PBPC grafts can be infused safely provided prophylactic antibiotic cover is given.

Bacteriological Techniques↗
PubMed1995

'Fifteen percent of microbiology reports are wrong!': further experience with an internal quality assessment and audit scheme.

Infection control teams critically depend on the quality of the diagnostic microbiology laboratories with which they are associated. Internal quality assessment (IQA) by specimen resubmission measures the consistency of laboratory performance and can be adapted for medical audit, but few laboratories appear to include these techniques as part of their quality control procedures. We established an IQA scheme in our bacteriology laboratory in May 1989, and the mean discrepancy rate for the first two years was nearly 15%. During the next two years covered by this report, the scheme was extended to include audit of the consistency of medical microbiologists' comments on reports, and a standardized scoring scheme was introduced. Results from the scheme are collated and analysed thrice yearly, and laboratory techniques altered and extra staff training planned to reduce discrepancies. Four thousand four hundred and fourteen specimens (1.4% workload) were resubmitted, and 325 (7.4%) gave discrepant results. During the two years, the overall discrepancy rate fell consistently from 9.4 to 3.2%. Fifty-three discrepancies (1.2%) were in microscopy, and 243 (5.5%) were between culture results. Substantial decreases in technical discrepancies followed training initiatives in sputum bacteriology, and training in anaerobic recognition and improved illumination in the anaerobic cabinet. Problems of consistent recognition of staphylococci and of urine isolates in mixed culture, and of faecal microscopy have proved difficult to eradicate. There was a 20.3% discrepancy rate between medical comments, but only 0.4% would have been likely to result in different patient outcomes. The cost of running the scheme was 4474 pounds per annum, equating to a surcharge of 0.058 pounds to each of our routine diagnostic specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic Errors↗
PubMed1995

Patterns of Cryptosporidium antigen and oocyst excretion in calves studied by reverse passive haemagglutination and light microscopy.

A reverse passive haemagglutination (RPH) assay incorporating a monoclonal antibody against Cryptosporidium parvum oocysts was used to follow Cryptosporidium coproantigen excretion by calves. RPH detected soluble antigen that passed 0.22 micron filters. Non-specific reactions that occurred in some samples were markedly reduced by heat treatment of the faecal specimens and were abolished by filtration after heat treatment. Results were compared with oocyst counts performed by microscopy of modified Ziehl-Neelsen (MZN) stained faecal smears. Five hundred and thirty-two daily specimens were examined from 30 calves. The mean age at which positive results for both oocysts and antigen was detected was 9 days (range 5-15 days), and excretion lasted for 5-11 days with some cycling of positive reactions in some calves. The occasional cycling to a negative reaction demonstrates a need to take samples from consecutive days to ensure diagnosis. Two hundred and ninety-one (54.7%) specimens were negative in both tests, 178 (33.5%) were positive in both, 14 (2.6%) were positive only by microscopy, and 49 (9.2%) were positive only by RPH. By these criteria the kappa coefficient of agreement between the tests was good (0.753). Compared with MZN, the sensitivity of RPH is 92.7%, specificity 85.6%, positive predictive value 78.4% and negative predictive value 95.4%. The method is simple, objective, has ease of quality control, and either single samples or batches can be processed.

Aging↗
PubMed1995

A scale for identifying "Stockholm syndrome" reactions in young dating women: factor structure, reliability, and validity.

The factor structure, reliability, and validity of a 49-item scale designed to measure Stockholm Syndrome (also referred to as "traumatic bonding" and "terror bonding"), that is, bonding with an abusive partner, were assessed for college women in heterosexual dating relationships. Factor analysis identified three major factors: Core Stockholm Syndrome, characterized by cognitive distortions and other strategies for coping with abuse; Psychological Damage, marked by depression, low self-esteem, and loss of sense of self; and Love-Dependence, typified by the feeling that one cannot survive without one's partner's love. The scale and factors had excellent internal consistency and good test-retest reliabilities. They correlated negatively with the Marlowe-Crowne Social Desirability scale and positively with Horowitz, Wilner, & Alvarez' (1979) Impact of Event Scale, Hyler and Rieder's (1987) Borderline Personality Disorder Scale, Hatfield and Sprecher's (1986) Passionate Love Scale, and Straus' (1979) Verbal Aggression and Violence scales of the Conflict Tactics Scales.

Adaptation, Psychological↗
PubMed1995

Anaesthetic drugs and bacterial contamination.

We investigated the bacterial contamination of commonly used intravenous anaesthetic agents. Ten trainee anaesthetists drew up four syringes each of propofol, midazolam, thiopentone, 0.9% saline and a culture medium control using their normal practice. A set of syringes was cultured at the time of drawing up and at 2, 4 and 8 h afterwards. No anaesthetist washed his or her hands before drawing up the drugs. Six anaesthetists capped the syringes using sheathed needles. Eight syringes were contaminated with bacteria. Coagulase-negative staphylococci were isolated from six syringes (four sheathed and two unsheathed) and an Acinetobacter sp. from two syringes (one sheathed and one unsheathed). No bacteria were cultured from the midazolam syringes. However, two syringes from each of the other solutions were contaminated. This implies that one syringe was contaminated when it was drawn up, at 2 h a further two had detectable contamination, two more were contaminated at 4 h and three more at 8 h. We cannot recommend drawing up drugs at the start of a list for use later in the day. They should be used immediately after drawing up. Basic hand washing before drawing up drugs may reduce contamination.

Anesthetics, Intravenous↗
PubMed1994

The morphological development of the inferior colliculus in a marsupial, the Northern quoll (Dasyurus hallucatus).

As a part of a project concerning the development of hearing, some features of the morphological development of the inferior colliculus were studied in a marsupial, the Northern quoll or native cat (Dasyurus hallucatus). Marsupials are of particular interest in developmental studies because much embryonic development occurs outside the uterus, in the pouch. Nissl-stained material was prepared from pouch-young at various ages between 11 and 81 days, and for a number of adults. Four pouch-young were injected with tritiated thymidine and killed later during pouch life. The inferior colliculus is first recognizable in pouch-young aged 23 days, when it is bordered by a cell-sparse ring of tissue. By this time, the labelling patterns following injections of tritiated thymidine made on days 7-9 suggest that migration of cells to the inferior colliculus from the ventricular germinal zone has been largely completed. At 81 days, close to the time when the young move out of the pouch, the adult cytoarchitecture--a central nucleus flanked by dorsal and lateral cortical regions--is clear. Cell areas expand monotonically as a function of age. The period of days 45-50 is associated with a large expansion of cell volume and a concomitant decrease in packing density. It is likely that functional connections are forming during this period, which may herald the onset of hearing in the quoll. Total cell numbers increase to a peak at day 36, fall to a minimum at day 50, and rise again to the adult value. The second increase is likely to be a phase of glial proliferation, in part associated with the onset of myelination. This increase correlates with departure of the young from the pouch.

Aging↗
PubMed1994

CD40 ligand expression is defective in a subset of patients with common variable immunodeficiency.

Common variable immunodeficiency (CVI) is characterized by hypogammaglobulinemia and recurrent bacterial infections due to failure of CVI B cells to differentiate in vivo into immunoglobulin-secreting plasma cells. We hypothesized that T-cell dysfunction resulting in abnormal contact-mediated B-cell activation may play a prominent role in the failure of CVI B cells to produce specific antibody. We have previously shown that B-cell proliferation and IgE production after stimulation with anti-CD40 and interleukin (IL) 4 were normal in 22 CVI patients evaluated, indicating that CVI B cells respond to signals delivered via CD40. Here we report that CD40 ligand (gp39) mRNA expression by activated lymphocytes from CVI patients (n = 31) as a group was significantly depressed (P < 0.0001) compared with normal controls (n = 32). gp39 mRNA expression by activated lymphocytes from 13 CVI patients fell below the normal control range. T-cell surface expression of functional gp39 protein was correspondingly low in those patients with gp39 mRNA levels below normal control range and normal in patients with gp39 mRNA levels within normal control range. In CVI patients as a group, gp39 mRNA levels correlated with IL-2 mRNA levels (P < 0.002, r = 0.6) and production (P < 0.001, r = 0.7) but not with gene expression or production of other lymphokines evaluated, suggesting an as-yet-undetermined association between gp39 and IL-2 gene regulation. Of the 13 patients whose activated T cells exhibited gp39 mRNA expression below the normal control range, 2 had normal T-cell-derived lymphokine production, whereas the remaining 11 exhibited broader T-cell dysfunction, resulting in IL-2 deficiency, and in some patients deficient production of other lymphokines as well, reflecting a heterogeneity in the underlying mechanisms leading to depressed gp39 expression in these patients. The observation that both gene and surface expression of gp39 by activated T cells is depressed in a subgroup of CVI patients suggests that inefficient signaling via CD40 may be responsible, in part, for failure of B-cell differentiation in these patients.

Adolescent↗
PubMed1994

Infective endocarditis of the pulmonary valve following pulmonary artery catheterisation.

The risk of infective endocarditis following pulmonary artery catheterisation in patients with sepsis remains unquantified. Although catheter-induced endocardial and valvular injury are well recognised, valve infection is rare. A case of mixed pulmonary valve endocarditis associated with the use of a pulmonary artery catheter (PAC) in a patient with multisystem failure following liver trauma is described. This illustrates that diagnosis of infective endocarditis in critically ill patients can be difficult because concurrent illness and therapy may mimic or mask the usual presenting signs. The value of transoesophageal echocardiography in this context is emphasised.

Adult↗
PubMed1994

Antibiotic irrigation and conservative surgery for major aortic graft infection.

PURPOSE: Traditional surgical treatment for panprosthetic aortic graft infection entails radical excision of the graft, aortic stump closure, and extraanatomic revascularization of the lower limbs. This carries an early mortality rate of 24% to 45%. Amputation rates range from 11% to 37%. Multiple operations and prolonged hospital stay are usual. We have developed a more conservative management technique with the aim of improving outcome. METHODS: We describe an innovative method of treating the condition with prolonged, high-dose, local antibiotic irrigation therapy, systemic antibiotic treatment, surgical debridement, and graft conservation in a prospectively studied series of 10 patients. RESULTS: The actual 30-day patient survival rate is 90%, the 1-year survival rate is 80%, and the 4-year survival rate is 67%. Two patients died because of graft infection, and the third died, uninfected, of an unrelated cause. No limbs have been amputated. Only two patients required a second operation. Mean postoperative hospital stay was 32 days. The seven survivors have been closely followed up with regular computed tomography or indium scanning and clinical examination and appear to be free from infection at a mean of 61 months after cessation of irrigation therapy. CONCLUSION: The technique appears to represent a significant improvement in the management of this major complication of vascular surgery.

Adult↗
PubMed1994

Fatal melioidosis in a tourist returning from Thailand.

Severe infections with Pseudomonas pseudomallei, the causative agent of melioidosis, is a common cause of community acquired septicaemia in South East Asia and parts of Northern Australia, but infection in travellers returning to the United Kingdom is extremely rare. We describe the case of a tourist who acquired melioidosis in Thailand. Despite intensive intravenous therapy with antibiotics to which the organism was sensitive, the patient's infection proved fatal. Ps. pseudomallei was isolated from blood cultures at a late stage in his illness by use of a commercial blood culture system that included an antibiotic removal device (Bac/TAlert, Organon-Technica).

Anti-Bacterial Agents↗
PubMed1994

Do infusions of midazolam and propofol pose an infection risk to critically ill patients?

In order to investigate bacterial contamination of i.v. anaesthetic agents, given by infusion to critically ill patients, we have cultured residual infusion fluid from infusion syringes, 50 containing midazolam and 50 propofol. The infusions had been prepared with routine aseptic precautions and had been running for between 0.75 and 21.25 h. Only scanty growths of Staphylococcus epidermidis were isolated from seven syringes (four midazolam and three propofol). Small volume samples were more likely to produce bacterial growth than large volume specimens. Midazolam infusions made up in 5% glucose were more likely to be contaminated than those made up in 0.9% saline. Antibacterial activity was detected in 18 midazolam and one propofol filtrate. Midazolam infusions inhibited the growth of all seven of the S. epidermidis isolates, whereas propofol supported similar rates of multiplication to that obtained with control broth medium. The results of this study imply that contamination of the infusions probably occurred after they were disconnected from the patient. Despite the ability of propofol to support microbial multiplication, we have no evidence to suggest that this is clinically significant when infusions are prepared with conventional aseptic precautions.

Bacterial Infections↗
PubMed1994

Cryptosporidium antigen detection in human feces by reverse passive hemagglutination assay.

A reverse passive hemagglutination (RPH) assay was developed for Cryptosporidium oocyst antigen with an antioocyst monoclonal antibody (MAb; MAb-C1) coupled to stabilized sheep erythrocytes. RPH was compared with microscopy of auramine-phenol-stained smears of 56 oocyst-positive fecal samples, each of which was tested blindly by RPH with two oocyst-negative samples received on the same day (a total of 112 controls). Thirty-nine additional fecal samples from human immunodeficiency virus type 1 antibody-positive patients with diarrhea (10 of which were positive in auramine-phenol-stained smears) were stored at -20 degrees C before testing. Thirty specimens with a variety of other fecal pathogens (all negative for oocysts) were also tested. Of the 237 samples tested, 69 were positive by one or both methods: 65 by RPH and 66 by microscopy. The kappa coefficient of agreement between the methods was very high at 0.926. The sensitivity of RPH was 93.9%, the specificity was 98.2%, the positive predictive value was 95.4%, and the negative predictive value was 97.7%. Visible oocyst numbers and RPH titers were measured after storage of fecal samples and oocyst concentrates for 8 days at 4 degrees C. Oocyst morphology was generally poor in specimens from the human immunodeficiency virus type 1 antibody-positive group, and it degenerated during the 8-day storage experiments. MAb-C1-reactive antigen eluted from oocysts to give progressively higher reciprocal titers during storage, and it was partially removed from the oocysts by concentration. RPH is a promising technique for the detection of Cryptosporidium antigen in human feces and may be useful when specimens are stored before testing. Studies of the sensitivity of Cryptosporidium immunoassays should take into account the possible release of antigen from oocysts.

Adolescent↗