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Biomedical subjects

D W Crook

Publications and source records attributed to D W Crook.

At least 19 recordsLinked to original sources
PubMed2004

Thrombosis of a superior mesenteric vein aneurysm: transarterial thrombolysis and transhepatic aspiration thrombectomy.

We report the case of a 31-year-old woman presenting with abdominal pain due to acute thrombosis of a superior and inferior mesenteric vein aneurysm, which was treated by a combination of arterial thrombolysis and transhepatic thrombus aspiration. At the last follow-up CT, 21 months following this procedure, there was no evidence of rethrombosis, and the patient continues to do well under oral anticoagulation. The literature regarding these uncommon mesenteric vein aneurysms without portal vein involvement, as well as their treatment options, is reviewed.

Adult↗
PubMed2004

Retrospectively ECG-gated multi-detector row CT of the chest: does ECG-gating improve three-dimensional visualization of the bronchial tree?

PURPOSE: To determine the impact of retrospectively ECG-gated multi-detector row CT (MDCT) on three-dimensional (3D) visualization of the bronchial tree and virtual bronchoscopy (VB) as compared to non-ECG-gated data acquisition. MATERIALS AND METHODS: Contrast-enhanced retrospectively ECG-gated and non-ECG-gated MDCT of the chest was performed in 25 consecutive patients referred for assessment of coronary artery bypass grafts and pathology of the ascending aorta. ECG-gated MDCT data were reconstructed in diastole using an absolute reverse delay of - 400 msec in all patients. In 10 patients additional reconstructions at - 200 msec, - 300 msec, and - 500 msec prior to the R-wave were performed. Shaded surface display (SSD) and virtual bronchoscopy (VB) for visualization of the bronchial segments was performed with ECG-gated and non-ECG-gated MDCT data. The visualization of the bronchial tree underwent blinded scoring. Effective radiation dose and signal-to-noise ratio (SNR) for both techniques were compared. RESULTS: There was no significant difference in visualizing single bronchial segments using ECG-gated compared to non-ECG-gated MDCT data. However, the total sum of scores for all bronchial segments visualized with non-ECG-gated MDCT was significantly higher compared to ECG-gated MDCT (P < 0.05). The summary scores for visualization of bronchial segments for different diastolic reconstructions did not differ significantly. The effective radiation dose and the SNR were significantly higher with the ECG-gated acquisition technique (P < 0.05). CONCLUSION: The bronchial tree is significantly better visualized when using non-ECG-gated MDCT compared to ECG-gated MDCT. Additionally, non-ECG-gated techniques require less radiation exposure. Thus, the current retrospective ECG-gating technique does not provide any additional benefit for 3D visualization of the bronchial tree and VB.

Adult↗
PubMed2003

Invasive pneumococcal disease in Oxford, 1985-2001: a retrospective case series.

AIMS: To describe a series of children with invasive pneumococcal disease (IPD). METHODS: A review of patient records for children aged 0-18 years admitted to the John Radcliffe Hospital with IPD from 1985 to 2001. Social deprivation was measured by the Jarman index. The proportion of children with congenital abnormalities was compared with national data. RESULTS: We identified 140 children with IPD; complete data were available for 136 children. The median age at diagnosis was 1.5 years. The social deprivation score of households of children with IPD was higher than that of the average Oxfordshire household (-2.5 v -7.3, p < 0.001). Forty four per cent of cases had at least one preceding health problem. The children with preceding health problems were significantly older than those with no preceding problems (median age 2.67 years, interquartile range 1.21 to 6.20 versus 1.11 years, interquartile range 0.51 to 2.21; p < 0.001). There was an increased risk of IPD for children with central nervous system malformations (OR = 99, 95% CI 31 to 236), congenital heart disease (OR = 62, 95% CI 24 to 131), and chromosomal abnormalities (OR = 32, 95% CI 6.6 to 96). CONCLUSIONS: There is an increased risk of IPD associated with increased social deprivation; and also with central nervous system malformations, congenital heart disease, and chromosomal abnormalities.

Adolescent↗
PubMed2000

Invasive pneumococcal disease in England and Wales: vaccination implications.

Knowledge of the epidemiology of invasive pneumococcal disease (IPD) will aid in planning the use of pneumococcal vaccines. A United Kingdom (UK)-based surveillance in England and Wales (1995-1997) of 11,528 individuals with IPD and a local enhanced surveillance in the Oxford (UK) area (1995-1999) have been analyzed. IPD has a high attack rate in children, with 37.1-48.1 cases per 100,000 infants <1 year old per year, and in older persons, with 21.2-36.2 cases per 100,000 persons >65 years old per year, for England, Wales, and Oxford. The 7-valent conjugate vaccine includes serotypes causing < or =79% of IPD in children <5 years old, but only 66% in adults >65 years old. The data also indicate that IPD varies by serotype, age, and country, emphasizing that the epidemiology of IPD is heterogeneous and requires continued surveillance.

Adolescent↗
PubMed2000

Molecular typing of bacteria directly from cerebrospinal fluid.

Using Streptococcus pneumoniae as an example, the ability of multilocus sequence typing (MLST) to characterise isolates directly from cerebrospinal fluid (CSF) was investigated. A nested multiplex polymerase chain reaction method that amplifies the seven housekeeping gene fragments used for pneumococcal MLST was applied to 30 CSF samples from suspected cases of bacterial meningitis. The fragments were amplified from all 14 samples from which Streptococcus pneumoniae was cultured, and, after direct sequencing, the allelic profiles obtained from ten of the samples corresponded to those of clones previously associated with invasive pneumococcal disease. MLST could also predict the penicillin susceptibility and serotype of the CSF isolates.

Alleles↗
PubMed2000

Epidemiological studies of large resistance plasmids in Haemophilus.

The distribution of large conjugative Haemophilus influenzae plasmids in the nasopharyngeal haemophili of a group of people and in a large collection of 541 H. influenzae type b (Hib) isolates was studied. A newly developed PCR-based assay was used to detect the plasmids. The target sequences were chosen from sequence analysis of part of p1056, a large multiresistance plasmid isolated from a clinical Hib isolate, 1056. Fifty-nine per cent of people were found to carry beta-lactamase-positive (beta-lac(+)), ampicillin-resistant (ampR) haemophili with detectable plasmid sequences. Of these, 83% were in Haemophilus parainfluenzae and 17% were in H. influenzae. In the collection of 541 Hib, antibiotic resistance [beta-lac(+)ampR, beta-lac(+)ampR plus tetracycline resistance (tetR) or tetR] was highly correlated with large plasmids. It was found that 2.3% of the isolates contained large cryptic plasmids (i.e. these isolates were susceptible to antibiotics). The distribution of plasmids between invasive and carried Hib did not differ significantly (25 of 245 and 23 of 276, respectively). Isolates with large plasmids occur at high frequency in the nasopharynx of the normal human population and consist of two populations in Hib, one associated with specific antibiotic resistance traits and the other cryptic. These plasmids do not appear to influence the invasiveness of Hib.

Adult↗
PubMed1998

Positive intravenous line tip cultures as predictors of bacteraemia.

Intravenous line tip cultures provide valuable information when taken in conjunction with blood culture, but in practice are often performed in isolation. This retrospective study has evaluated: (1) the frequency of isolated line tip culture; and (2) whether the species of microorganism isolated from line tip culture, using the Maki semi-quantitative culture method, is predictive of bacteraemia. Of 2753 line tip culture episodes in 1659 patients between May 1993 and August 1995, 2230 were performed in isolation (81%). Evaluation of 792 positive line tip culture episodes in 654 patients where blood cultures were performed in the period from 48 h before, to 24 h after tip culture, identified 825 line tip isolates. Of these, 194 were associated with a blood culture positive for the same species. The rate of positive blood culture, according to species, ranged from 10-72%. The highest rate was seen for methicillin-susceptible Staphylococcus aureus where 70 of 97 line tip episodes (72%) were associated with positive blood culture. This compared with a rate of 17% for coagulase-negative staphylococci (P < 0.0001). Patients with line tip cultures positive for S. aureus should be considered to be at high risk of bacteraemia.

Bacteremia↗
PubMed1998

Multiple antibiotic resistance in Streptococcus pneumoniae.

Streptococcus pneumoniae remains a major pathogen responsible for high morbidity and mortality in both the developed and developing world. During the last few years there has been a dramatic increase in the incidence of penicillin-resistant and multiply antibiotic-resistant pneumococci, and the emergence of isolates with high-level resistance to extended-spectrum cephalosporins. In several countries, 50-80% of pneumococcal isolates, including the great majority of isolates of the serotypes associated with disease and carriage in children, are penicillin-resistant. Penicillin-resistant pneumococci are diverse, but in several countries successful highly penicillin-resistant clones (which in most cases are resistant also to tetracycline, chloramphenicol, and cotrimoxazole, and increasingly to erythromycin) have emerged, and some of these have spread globally. The effect of antibiotic resistance on the clinical outcome of otitis media, pneumonia and meningitis, and the potential of the new conjugate vaccines for controlling pneumococcal disease, are discussed.

Drug Resistance, Microbial↗
PubMed1998

Prospective evaluation of criteria for microbiological diagnosis of prosthetic-joint infection at revision arthroplasty. The OSIRIS Collaborative Study Group.

A prospective study was performed to establish criteria for the microbiological diagnosis of prosthetic joint infection at elective revision arthroplasty. Patients were treated in a multidisciplinary unit dedicated to the management and study of musculoskeletal infection. Standard multiple samples of periprosthetic tissue were obtained at surgery, Gram stained, and cultured by direct and enrichment methods. With reference to histology as the criterion standard, sensitivities, specificities, and likelihood ratios (LRs) were calculated by using different cutoffs for the diagnosis of infection. We performed revisions on 334 patients over a 17-month period, of whom 297 were evaluable. The remaining 37 were excluded because histology results were unavailable or could not be interpreted due to underlying inflammatory joint disease. There were 41 infections, with only 65% of all samples sent from infected patients being culture positive, suggesting low numbers of bacteria in the samples taken. The isolation of an indistinguishable microorganism from three or more independent specimens was highly predictive of infection (sensitivity, 65%; specificity, 99.6%; LR, 168.6), while Gram staining was less useful (sensitivity, 12%; specificity, 98%; LR, 10). A simple mathematical model was developed to predict the performance of the diagnostic test. We recommend that five or six specimens be sent, that the cutoff for a definite diagnosis of infection be three or more operative specimens that yield an indistinguishable organism, and that because of its low level of sensitivity, Gram staining should be abandoned as a diagnostic tool at elective revision arthroplasty.

Arthroplasty, Replacement, Hip↗
PubMed1997

Methicillin susceptibility testing of staphylococci by Etest and comparison with agar dilution and mecA detection.

The susceptibility to methicillin of 44 Staphylococcus aureus and 120 coagulase-negative staphylococci (CNS) was determined by Etest, agar dilution and presence of the mecA gene. There was agreement between the results of all methods when testing S. aureus. However, discrepancies occurred with CNS when cultural methods were compared with presence of the mecA gene. mecA-positive isolates tested as resistant more often with agar dilution on Columbia agar plus 5% NaCl than by Etest.

Bacterial Proteins↗
PubMed1997

A molecular analysis of Greek and UK Haemophilus influenzae conjugative resistance plasmids.

Antibiotic resistance in Haemophilus influenzae has been associated with the presence of large, chromosomally integrated, conjugative plasmids. The plasmids of 10 beta-lactamase-positive, ampicillin-resistant strains, two from the UK and eight from Greece, were investigated. Plasmids were detected and isolated after transfer to a rec-deficient recipient. Purified whole plasmid was used as probe. In addition a 12 kb PstI fragment containing the putative point of recircularization in one plasmid, p1056, was cloned and used as a probe. All plasmids shared a high degree of sequence homology suggesting that plasmids of diverse geographical origin are highly related. All plasmids also shared sequence homology with the 12 kb PstI fragment containing the point of recircularization, suggesting that the sequences involved in excision and recircularization are conserved.

Ampicillin Resistance↗
PubMed1997

Antibody persistence and Haemophilus influenzae type b carriage after infant immunisation with PRP-T.

OBJECTIVES: To assess the persistence of serum Haemophilus influenzae type b antibodies and the prevalence of H influenzae type b carriage in a group of preschool age children previously vaccinated in infancy. DESIGN: Names were randomly selected from immunisation records. Families were visited on five occasions over a period of 12 months and throat swabs were taken from all family members present, with blood obtained from children at the first and last visits. RESULTS: One hundred and fifty three children at a median age of 3.6 years had a geometric mean titre (GMT) of 1.06 micrograms/ml (95% CI 0.80 to 1.38). Eight per cent had an undetectable antibody concentration, received a booster dose of plain PRP vaccine, and responded with concentrations > 2 micrograms/ml. GMT at 4.5 years of age was 0.89 microgram/ml (0.69 to 1.16). Twelve children who had been exposed to H influenzae had a GMT of 4.7 v 0.8 micrograms/ml for those without exposure. CONCLUSIONS: Accelerated immunisation against H influenzae without a second year booster results in persistence of satisfactory serum concentrations of antibody to 4.5 years of age. In those with undetectable antibody, immunological memory may still be present.

Antibodies, Bacterial↗
PubMed1996

Safe intravenous antibiotic therapy at home: experience of a UK based programme.

Outpatient i.v. antibiotic therapy is well developed in the United States, largely because of pressures from third-party payers to reduce costs of medical care. We have developed an outpatient i.v. antibiotic programme in Oxford, that has evolved from a desire to provide high quality i.v. therapy to AIDS patients with cytomegalovirus retinitis. We describe the rationale of the service and report on our first two years' experience. We treated 67 consecutive patients (eight with HIV infection) at home with i.v. antibiotics. This resulted in a saving of 2275 hospital days for those patients without HIV infection. HIV positive patients received 69 months of home i.v. therapy. Minor intravascular catheter complications occurred in only five patients (7.5%). The only serious complications were three episodes of catheter-related sepsis (4.5%), all occurring in AIDS patients who had lines in for more than six months. We have shown that home i.v. antibiotic therapy can be delivered safely to patients with a wide variety of infectious problems using the existing network of community nurses in the National Health Service. Essential components to the programme include a multidisciplinary team working between the hospital and community and a written shared care protocol. Such a programme can result in reduced lengths of hospital stay and patient, community nurse and physician satisfaction.

Anti-Bacterial Agents↗
PubMed1996

Native-valve endocarditis caused by Staphylococcus lugdunensis.

Coagulase-negative staphylococci cause about 5% of native-valve endocarditis. Staphylococcus lugdunensis, a recently-described species of coagulase-negative staphylococci, has been reported to cause destructive native-valve endocarditis with a high mortality. We report four consecutive cases of definite Staphylococcus lugdunensis native-valve endocarditis by the Duke criteria over a 4-year period. All patients required urgent aortic valve replacement 1-5 days after admission, and recovered. An intriguing, aspect in the presentation of these patients was a history of vasectomy and inguinal skin breaks in the immediate period preceding the occurrence of endocarditis.

Adult↗