Biomedical subjects
Publications and source records attributed to D A McSwiggan.
In two outbreaks of diarrhoea and vomiting that were caused by a small round structured virus (SRSV) that affected over 275 people, epidemiological and laboratory evidence showed that certain foods were the vehicles of infection and suggest that one of the chefs who prepared them may have been excreting this virus for a long time.
Batches of pooled immune globulins and sera were tested by immune electron microscopy (IEM) for the presence of antibodies to a strain of human calicivirus (HCV, UK1). The results show that this strain of HCV is prevalent throughout many parts of the world and that the majority of the population experience infection by the age of 12 years. The survey carried out in the United Kingdom indicates that the presence of maternal antibody correlates with some degree of protection during the first few weeks of life; the peak incidence of cases and acquisition of antibody occur between 3 months and 6 years. Tests on sera from Japan show a similar pattern of acquisition of antibodies and demonstrate that infection with more than one strain of HCV commonly occurs during childhood.
Aplastic and hypoplastic crises are well recognised complications of sickle cell disease. Recent evidence has shown that most of these crises are caused by parvovirus infection. Five cases of aplastic or hypoplastic crises in patients born and living in this country were studied. Three patients had clear evidence of parvovirus infection, while in two evidence of parvovirus infection was lacking. One patient had evidence of concurrent parvovirus and Mycoplasma pneumoniae infection. Recurrent crises may occur, and reticulocyte monitoring during infection in patients with chronic haemolytic states is therefore important.
A large outbreak of viral gastroenteritis occurred in which oysters eaten raw were the vehicle of infection. Laboratory findings indicated that a small round structured virus was the infecting agent. Adults of all ages were equally susceptible to infection with the virus. Investigation cast doubt on the efficacy of depuration as a method for rendering oysters free of virus, and hence the public should be warned of the hazard of eating raw shellfish.
An assessment of the educational value of a series of courses intended to improve the clinical awareness of non-medical graduate microbiologists has been made. Objective and subjective data were collected by means of questionnaires, pre- and post-course multiple choice tests and informal discussion. The format of the courses are described. The increase in cognitive knowledge acquired during three of the courses is comparable with results from another study in clinical students. The anomalous results from one of the four courses may be explained in terms of the composition of that course. The data presented contribute to the information required for the evaluation and assessment of educational courses.
Ninety-eight patients were studied. Ninety were consecutive patients who were isolation-positive for adenovirus, and 8, who were associated with a hospital outbreak of adenovirus serotype 8 infection, developed characteristic features of infection but were isolation-negative. The ratio of males to females was 2 to 1, and most patients were aged 20 to 39. Adenovirus serotypes 3, 7, and 8 were isolated from 86% of patients, and serotypes 2, 4, 5, 11, 15, and 15/29 from the remaining 14%. Adenovirus serotype 7 was more commonly isolated from patients under the age of 19 and was Not isolated during winter. Sources of infection could be identified in 36% of patients and included contact with upper respiratory tract of ocular infections, a hospital outbreak, and a recent visit to a swimming pool. Associated systemic disease was detected in 47% of patients, most of whom had upper respiratory tract infection. The most severe and prolonged conjunctivitis was caused by serotypes 5 and 8. Most patients developed epithelial punctate keratitis. Subepithelial punctate keratitis, which was once-considered to be a characteristic feature of adenovirus serotype 8, developed in cases of serotype 3, 4, 5, 7, and 8 infection.
During the period 1973-8 700 adenoviruses were isolated from the eyes of patients presenting at Moorfields Eye Hospital. Of these, 678 were serotyped by a neutralisation test. Twenty-one different serotypes were identified. Serotype 3, 7, and 10 accounted for 68% of the isolates, 4, 8, 15 (15/29), and 19 for 25%, and the other 14 serotypes for 7%. Community outbreaks of ocular infections by adenovirus 3, 4, 7, 10, and 15 (15/29) were observed. Outbreaks with adenovirus 3, 7, and 10 appeared to continue for 2 years or more, whereas outbreaks with 4 and 15 (15/29) were restricted to one year or less. Hospital outbreaks by adenovirus 8 and 19 were also recorded. During the same period 18 of these 21 adenovirus serotypes were isolated from the nonocular sites (mainly respiratory tract) in 7804 cases. There was a close association in the distribution of adenovirus 1, 2, 3, 5, and 6 in the ocular and nonocular sites. No such association was observed for adenovirus serotypes 4, 8, 10, 15 (15/29), and 19.
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A 28 day survey of all antibiotic prescriptions in a district general hospital included a brief interview with the prescriber of each prescription. Fifty-nine antibiotic courses were stated by the prescriber to be for the treatment of urinary tract infection (UTI). Urine specimens from all patients treated for UTI were sent to the laboratory for bacteriological examination. 29 patients' treatment was started as the result of isolation of bacteria from the urine. 20 of the patients also had symptoms suggestive of UTI. 4 patients were treated solely because bacteria had been isolated from "routine" catheter stream urine specimens. 7 patients were treated for UTI despite the availability, at the time of prescription, of a laboratory report stating that bacteria had not been isolated from the urine. 19 patients' treatment was started before the results of bacteriological tests were available. By combining information about bacteriological examination of the urine specimens and clinical details recorded during the interview with the prescribed, it was considered that both initiation and continuation of antibiotic treatment was justified for 28/55 patients and that either initiation or continuation of treatment was unjustified for 27/55 patients.
A 28 day survey of all antibiotic prescriptions in a district general hospital included a brief interview with the prescriber of each prescription. One hundred and nineteen antibiotic courses were stated, by the prescriber, to be for the treatment of lower respiratory tract infection. By combining the prescriber's clinical evidence, laboratory data, and radiographic findings, an "index of infection" was produced for 94 patients. This index reflected features associated with bacterial infection of the lower respiratory tract and suggested that 49% of the antibiotic courses prescribed were justifiable, 11% were questionable, and 40% were unjustifiable. The choice of antibiotic was usually appropriate to the prescriber's diagnosis. Over 80% of the antibiotics used were of the penicillin group. Ampicillin, the single most frequently prescribed drug, accounted for 60% of the prescriptions. The frequency of diagnosis of chest infection increased with age. Almost 40% of patients over 81 years old who were admitted to hospital during the survey were prescribed antibiotics for chest infection. A higher proportion of older than of younger patients had low indices of infection.
In a survey of all antibiotic prescription in a district general hospital during November, 1978, the reason for each prescription was determined by a brief interview with the prescriber. 28% of all inpatients received antibiotics. Older patients were prescribed antibiotics more often than were younger patients. Ampicillin was the most frequently used antibiotic, accounting for over 40% of prescriptions. Over 70% of antibiotic courses were stated by the prescriber as being for the treatment of infection and the remainder were said to be prophylactic. Although 80% of the antibiotics were assessed as suitable treatment for the stated infection, most of the patients were treated without bacteriological evidence of the infecting agent and, for these patients, prescribers were unable to specify the pathogen against which treatment was intended in 50% of the courses they initiated. Only 7% of antibiotics prescribed for conventional surgical prophylaxis fulfilled all the criteria used to assess the suitability of choice of drug and the method and timing of its administration.
An outbreak of hospital-acquired klebsiella infection was investigated by means of six different typing schemes. Interpretation of the information generated by these schemes proved difficult and allowed only tentative conclusions to be reached concerning the origin of some strains. Consequently, the results were subjected to computer analysis by means of a numerical taxonomic programme adapted for the purpose. A dendrogram was constructed giving the percentage similarity between strains. It established the source of four atypical strains and showed that three of them were derived from the original clone. This form of numerical epidemiological analysis could have useful applications in the investigation of hospital-acquired infection.
A comparison has been made of the efficiency of 3 cell systems, human embryo kidney (HEK), Hep 2, and a continuous line of human embryo intestine (HEI), for the isolation of ophthalmic viruses. A total of 40 herpes simplex, 51 adenoviruses, and 2 vaccinia viruses were isolated from 323 specimens. HEK cells were found to be the optimal system, 85 out of 93 (91%) of the viruses being detected in these cells alone. However, HEK cells are difficult to obtain, and therefore the use of a combination of the continuous cell lines HEI and Hep 2 is recommended as an alternative. 89% of the viruses were detected by this combination. The use of either HEI or Hep 2 cells alone was unsatisfactory.
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A small outbreak of infection due to a calicivirus occurred in a mother and baby unit. All the infants showed evidence of infection but the clinical features varied. None of the staff or mothers showed evidence of illness, and antibody studies indicated past experience of this virus.
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