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Biomedical subjects

D J Waghorn

Publications and source records attributed to D J Waghorn.

At least 19 recordsLinked to original sources
PubMed2001

Overwhelming infection in asplenic patients: current best practice preventive measures are not being followed.

AIMS: Patients without spleens are at increased risk of overwhelming infection. Recently, greater efforts, including the publication of national guidelines, have been made to improve the management of asplenic individuals. In theory, risks of serious sepsis can be reduced by good advice, immunisation, and antibiotic prophylaxis. In practice, such preventive measures might not be followed or may fail. A study of recent cases of overwhelming postsplenectomy infection (OPSI) was undertaken to examine specific associated factors and to determine whether currently recommended preventive measures are being followed. METHODS: Cases of OPSI were identified and reported mainly by microbiologists across the country using a specifically designed proforma. Data including the nature of the infection and vaccination/ antibiotic prophylaxis history since splenectomy were obtained. RESULTS: Seventy seven cases were reported. The age range varied from 3 months (congenital asplenia) to 87 years. In those who had undergone surgical splenectomy, the time interval between surgery and OPSI varied from 24 days to 65 years. Overall mortality reached 50%, with underlying haematological malignancy associated with the highest death rate. Streptococcus pneumoniae caused approximately 90% episodes. Only 31% individuals had received pneumococcal vaccination before OPSI. Seven of 17 pneumococcal infections in immunised cases could be considered vaccine failures. Few patients had been adequately advised on antibiotic prophylaxis or other measures. CONCLUSIONS: Currently accepted best practice for managing asplenic patients is not being followed. Some OPSI cases may still be preventable but many asplenic individuals remain unrecognised. The compilation of asplenic patient registers might help to implement agreed policies with audit necessary to evaluate compliance. More is needed to ensure optimal management for this cohort of the population.

Adolescent↗
PubMed2000

The serodiagnosis of infection with Salmonella typhi.

BACKGROUND/AIMS: The serodiagnosis of infection with Salmonella typhi, using the Widal agglutination assay, relies on patients' antibodies to the O = 9,12 lipopolysaccharide (LPS) antigens, H = d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection with S typhi. In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens. METHODS: The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation of S typhi, ViI Bhatnagar variant strain (S typhi, ViI). Sera used in the study comprised 73 from patients who were culture positive for S typhi, 10 from patients who were culture positive for other species of Salmonella not expressing a Vi antigen (namely, S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly, or S mbandaka), and eight from healthy blood donors. RESULTS: Agglutination titres of > or = 1/40 were detected to S typhi ViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies to S. typhi ViI in all eight control sera and seven sera from patients infected with S bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley. CONCLUSIONS: Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections with S typhi should be based on the detection of antibodies to both the O = 9,12 LPS antigen and the H = d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.

Agglutination Tests↗
PubMed1998

Heterogeneous location of the mupA high-level mupirocin resistance gene in Staphylococcus aureus.

Epidemiologically unrelated clinical isolates of Staphylococcus aureus with high-level resistance to mupirocin (MIC > or = 512 mg/L) were studied to determine the location of the mupA resistance gene. The gene was carried on plasmids of variable size, some of which were transferable in vitro. DNA hybridisation of genomic DNA from 85 isolates showed that mupA was located on EcoRI fragments of seven different sizes; the most frequently observed fragments were 7 kb (46 isolates) or 4.1 kb (21 isolates). All isolates retained a 1.6-kb Nco I fragment that hybridised with mupA probes, but showed heterogeneous hybridisation patterns after digestion with Hinc II. These data suggested that mupA may be conserved, but that variation occurs in the flanking DNA proximal to it. Amplification of spacer regions between mupA and closest proximal copy of IS257 yielded products of variable size and was consistent with the presence of IS257 in either orientation. It is proposed that IS257-mediated events are responsible for the heterogeneity observed. The location of mupA varied between epidemiologically unrelated isolates of the same strain, including isolates of EMRSA-16 -- one of the two predominant methicillin-resistant strains in UK hospitals at the present time -- and this correlated with variations in the digestion patterns of the mupirocin resistance plasmids. The variable location of mupA should be evaluated further as a potential epidemiological tool with which to monitor the spread of high-level mupirocin resistance in EMRSA-16 or other strains of S. aureus.

Anti-Bacterial Agents↗
PubMed1998

Collaborative approach to improve the detection and management of trichomoniasis in a low prevalence district.

We describe a simple collaborative approach developed by the departments of cytology, microbiology and genitourinary (GU) medicine for the detection, diagnosis and management of microbiologically confirmed Trichomonas vaginalis (TV) infection. Over a 2-year period, 54 (0.1%) of 52,440 cervical smears were reported to show TV, but microbiological confirmation was made in only 76% of 34 patients from whom a vaginal swab was subsequently taken. Trichomoniasis should not be diagnosed by cytology alone and clinicians need further education on the role of cytology in diagnosing sexually transmitted diseases (STDs). Over the same period, from a total of 96 cases of TV identified in the district, only 12 (13%) were first diagnosed in the department of GU medicine. Forty per cent of the other 84 patients were subsequently seen in the GU clinic for test of cure, contact tracing and screening for other STDs. Collaborations between departments may improve the management of trichomoniasis and other conditions in the community and their development should be encouraged.

Animals↗
PubMed1997

A study of 42 episodes of overwhelming post-splenectomy infection: is current guidance for asplenic individuals being followed?

Individuals without a spleen have an increased risk of overwhelming post-splenectomy infection (OPSI). Improved awareness in recent years has stimulated increased efforts to prevent OPSI. Published guidelines have described policies for immunization, chemoprophylaxis and other measures considered beneficial to asplenic patients, yet OPSI episodes continue to occur. In an attempt to investigate why serious infections are still being seen, we have conducted a nationally based survey of recent OPSI episodes, using mainly a network of medical microbiologists. Data including clinical background to both splenectomy and OPSI episode, immunization and chemoprophylaxis history have been collated. Forty-two cases of overwhelming infection were reported by June 1996. Patients of all ages were affected with OPSI occurring up to 59 years after splenectomy. A mortality rate of 45% was seen. Pneumococcal infection caused at least 37 of 42 episodes, but only 12 patients had received pneumococcal vaccine. Four cases were possible vaccine failures. Only 22% of individuals had taken any chemoprophylaxis since splenectomy, and only one carried a medical alert card. Much more needs to be done to ensure that asplenic patients are warned of the risks of infection, and given at least pneumococcal vaccine. The role of antibiotics for either continual prophylaxis or as a reserve supply for self-prescription at appropriate times also needs greater discussion. Further work on improving pneumococcal vaccine response together with suitable programmes for revaccination are required. Surveillance should continue until the incidence of OPSI reaches an irreducible minimum.

Adult↗
PubMed1995

Management of asplenic patients in South Buckinghamshire: an audit of local practice.

People without spleens have an increased risk of pneumococcal and other infections. Immunisation is advised for this group of patients, but the role of prophylactic antibiotics remains unresolved. Since 1992, general practitioners in South Buckinghamshire have been encouraged to immunise all asplenic patients against infections with Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b (Hib). In addition, an 'alert' card, similar in principle to a medical warning bracelet, has been produced for general practitioners to issue to asplenic patients. General practitioners' clinical records of 293 asplenic patients were subsequently examined to evaluate this programme and assess the use of prophylactic antibiotics. Uptakes of 91%, 80%, and 79% were achieved for vaccines against pneumococcal, meningococcal, and Hib infections, respectively. Twenty-three per cent of patients had been advised immediately after splenectomy to take prophylactic antibiotics. Prophylaxis was advised for different periods of time, particularly in children. Thirty-four different antibiotic regimens had been recommended for adults. Clinical records suggested that 9% of patients were taking antibiotic prophylaxis at the time of the analysis. 'Alert' cards had been distributed to 88% of patients who were eligible. It is likely that most districts within the United Kingdom could set up similar immunisation and 'alert' card programmes. The wide variation in recommendations for antibiotic prophylaxis highlights the need for further research and the development of national guidelines.

Adolescent↗
PubMed1995

Serological testing in a microbiology laboratory of specimens from patients with suspected infectious disease.

AIMS: To determine how the microbiology laboratories of one region process serological requests from patients with suspected infectious illness, referred to as "clinical syndrome" type patients in this study; to consider areas where improvement in the associated serology service could be made. METHODS: A prospective two month collection of data on all serological requests from patients with suspected infectious illness was undertaken. A questionnaire on laboratory policies/procedures was also completed by the 10 departments taking part. RESULTS: Serology specimens from "clinical syndrome" patients accounted for 1-2% of total microbiology samples. There was significant variation in some of the policies/procedures carried out by the 10 laboratories when handling serological requests. Differences were seen in the use of laboratory protocols for test processing, range of tests performed, demand for second (convalescent) serum samples, storage of serum samples, and reporting of results. CONCLUSIONS: The laboratory management of "clinical syndrome" type requests is complex. Individual pathology departments vary in the way they handle serology specimens but this study highlighted areas which may contribute to improving the appropriateness of testing and the more efficient use of serology resources. These include improving (1) clinician education, (2) pathology request forms to encourage better clinical information, (3) appropriate laboratory protocols to aid decision making on test selection, (4) percentage of convalescent serum samples received together with longer serum sample storage, and (5) turnaround times of serology reports.

Clinical Protocols↗
PubMed1994

Intravascular device-associated systemic infections: a 2 year analysis of cases in a district general hospital.

The increasing use of intravascular devices (IVDs) throughout medicine has been accompanied by significant morbidity and mortality associated with catheter-related sepsis (CRS). Within the South Buckinghamshire district, 330 episodes of bacteraemia/fungaemia were recorded over the 2 year period 1992-1993. Thirty-nine episodes (12%), occurring in 37 patients, were associated with IVDs and these were divided into three groups according to the type and site of device. Six patients died with CRS contributing to mortality whilst one patient suffered serious morbidity, in the form of vertebral osteomyelitis. This analysis highlighted deficiencies in the management of IVDs which are likely to be found in similar district general hospitals in the UK. There is an urgent need for national guidelines on IVD care together with recommendations for the optimal treatment of IVD-associated infection.

Bacteremia↗