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Biomedical subjects

P G Flanagan

Publications and source records attributed to P G Flanagan.

At least 19 recordsLinked to original sources
PubMed2003

Evaluation of the Idaho Technology LightCycler PCR for the direct detection of Mycobacterium tuberculosis in respiratory specimens.

SETTING: The rapid detection of Mycobacterium tuberculosis (TB) in clinical samples is an important goal. The LightCycler heralds an advance in thermal cycle technology combining rapid cycle DNA amplification with fluorimetry, eliminating the need to perform amplification and product analysis separately. OBJECTIVES: To evaluate the LightCycler for direct detection of M. tuberculosis complex in respiratory specimens. To evaluate a DNA extraction method based on Chelex 100 resin, heating and ultrasonication for the prevention of endogenous inhibitions in respiratory samples. DESIGN: DNA was extracted from sputum samples using the Chelex method and polymerase chain reaction (PCR) for TB performed with the LightCycler. RESULTS: For 88 sputum samples positive by microscopy and culture for M. tuberculosis, 95% were PCR-positive. None of the five sputum samples that were smear-negative but culture-positive for M. tuberculosis, the 79 culture-negative sputum samples and the 29 sputum samples that were culture-positive for mycobacteria other than TB yielded positive PCR results. PCR inhibitors were not detected in any of the samples. CONCLUSION: The LightCycler proved a simple, reproducible and rapid system, reducing the time to result from weeks (culture) or days (conventional PCR) to hours. The Chelex 100 resin method produced good results for the smear-positive specimens. However, a larger study is required to determine the efficacy of the method with smear-negative specimens and for specimens known to contain endogenous inhibitors.

Fluorometry↗
PubMed2001

Diagnosis of gram negative, ventilator associated pneumonia by assaying endotoxin in bronchial lavage fluid.

AIM: To investigate the usefulness of assaying endotoxin in non-directed bronchial lavage fluid (NBL), bronchoscopic bronchoalveolar lavage fluid (BAL), and sera as a means of diagnosing Gram negative, ventilator associated pneumonia. METHODS: Samples from 64 patients were investigated. Fifty nine BALs and 92 NBLs were assayed in total including specimens taken during 28 episodes of clinical ventilator associated pneumonia (VAP). RESULTS: The concentration of endotoxin in BAL from patients with VAP developing within four days of commencing ventilation was significantly higher than in those without VAP (p = 0.015). There was no significant difference in endotoxin concentration in NBL or serum when comparing patients with and without VAP. A BAL endotoxin concentration of 6 EU/ml yielded the optimal operating characteristics (sensitivity, 81%; specificity, 87%; positive predictive value, 67%; negative predictive value, 95%). However, Gram stain of BAL provided the same information as quickly as the endotoxin assay and is considerably cheaper. CONCLUSIONS: Despite its accuracy and rapidity, the BAL endotoxin assay must be shown to alter clinical management and patient outcome to be cost effective.

Adult↗
PubMed2000

The diagnosis of ventilator-associated pneumonia using non-bronchoscopic, non-directed lung lavages.

OBJECTIVES: (1)To assess the diagnostic utility of quantitative cultures of non-bronchoscopic lung lavage (NBL) in ventilator-associated pneumonia and evaluate the role of the Bacterial Index; (2) To assess the predictive value of NBL surveillance quantitative cultures in ventilated patients; (3) To evaluate the Clinical Pulmonary Infection Score (CPIS) system in ventilated patients. DESIGN: A prospective comparison of NBL with bronchoscopic bronchoalveolar lavage and protected specimen brush. SETTING: Three intensive care units in academic tertiary care centres. PATIENTS: 145 adults ventilated for 72 h, with and without clinical signs of pneumonia. INTERVENTIONS: Sampling of lower airway secretions by NBL, bronchoalveolar lavage and protected specimen brush. MAIN OUTCOME MEASURES: Diagnostic reliability of quantitative cultures, Bacterial Index and CPIS. RESULTS: 34 episodes of clinical ventilator-associated pneumonia were documented in 32 patients. 9 episodes were confirmed by concordant blood/pleural culture or post-mortem lung examination. Qualitative concordance of the predominant pathogen between sequential NBL: bronchoalveolar lavage and protected specimen brush was 83 %. Sensitivity and specificity of non-directed bronchial lavage at a threshold of 10(4) CFU/ml were 68 % and 70 % respectively (p = 0. 003) and were comparable with the bronchoscopic methods. However, the low positive predictive value of NBL indicates that quantitation in the absence of clinical signs is unlikely to be useful. Bacterial Index did not improve discriminatory power of quantitation compared with bacterial load of predominant organism. Mean CPIS for confirmed pneumonia cases was 8.4 +/- 1.01, significantly higher than for non-pneumonia observations (p = < 0.0001). CONCLUSION: NBL is a simple, safe, cheap, readily-available method of diagnosing ventilator-associated pneumonia with comparable diagnostic accuracy to bronchoscopic techniques. Quantitation of respiratory tract cultures can exclude pneumonia in patients with equivocal clinical signs. The diagnostic threshold should vary depending on the length of ventilation, likelihood of pneumonia and antibiotic administration. The Bacterial Index is a flawed mathematical device that has no contributory role in pneumonia diagnosis. The CPIS has some diagnostic role in selected cohorts of ventilated patients.

APACHE↗
PubMed2000

Treatment of a vancomycin-resistant Enterococcus faecium ventricular drain infection with quinupristin/dalfopristin and review of the literature.

Central nervous system infections involving vancomycin-resistant Enterococcus faecium (VREF) are infrequently described and pose significant therapeutic difficulties, because these organisms are intrinsically resistant to many antibiotics. We describe the use of intrathecal quinupristin/dalfopristin to treat a VREF-associated infection in a neuro--surgical patient.

Acetamides↗
PubMed1999

Comparison of two automated systems for the isolation of mycobacteria from clinical specimens.

The Bactec MGIT 960 (Becton-Dickinson, UK) automated mycobacterial liquid culture system was compared with the Bactec 9000 MB (Becton-Dickinson) in order to assess ease of use, diagnostic reliability and safety features. One thousand twenty-nine clinical specimens were cultured in parallel, yielding a total of 125 (12.1%) mycobacterial isolates, including 71 Mycobacterium tuberculosis and 18 Mycobacterium avium. The Bactec MGIT 960 demonstrated a mycobacterial recovery rate and speed of detection equivalent to that of the Bactec 9000 MB for clinically important isolates. The Bactec MGIT 960 integrates smoothly into laboratory workflow, does not require needle inoculation and has a much larger capacity than the Bactec 9000 MB.

Bacteriological Techniques↗
PubMed1999

Diagnosis of ventilator-associated pneumonia.

The diagnosis of ventilator-associated pneumonia (VAP) is problematic despite numerous attempts at defining acceptable diagnostic criteria and the optimal technique for routine respiratory sampling. Clinical criteria have imperfect diagnostic reliability in ventilated patients, but remain crucial for defining those patients who may require respiratory sampling. Quantitative clinical scoring systems may improve the accuracy of clinical diagnosis in some ventilated patients. Review of published studies suggest that fibreoptic bronchoscopic techniques have greater diagnostic reliability than qualitative endotracheal aspirates, despite inconsistent results when comparing the same techniques in different centres. However, the cost and invasive nature of bronchoscopic methods precludes their use as first-line techniques in VAP. Non-bronchoscopic, non-directed techniques are cheaper, safer and more widely available alternatives to fibreoptic bronchoscopy techniques and have comparable accuracy. Quantitation of respiratory tract cultures is useful in excluding VAP in patients with equivocal signs of pneumonia. The diagnostic threshold of bacterial load that defines the presence of VAP should vary according to the pre-test probability of pneumonia, length of ventilation, antibiotic administration and immunocompetence of the patient.

Adult↗
PubMed1998

Fungal infection in the intensive care unit.

Fungal infection in critically ill patients is an increasingly prevalent problem. Candida spp. cause the majority of these infections in ICU. They occur most commonly in patients with severe underlying illness, multiple courses of antibiotics and intravascular catheters. Clinical diagnosis is difficult due to nonspecific signs and the frequent occurrence of widespread superficial colonization with Candida spp. in ventilated patients. Most patients are diagnosed using inferential evidence of infection, such as persistent pyrexia despite antibiotics, raised serum C-reactive protein and the presence of individual risk factors. Amphotericin B and fluconazole are the most commonly used anti-fungals dependent on the identity of the fungus. Most of these infections are endogenous; however, a proportion may be caused via the hands of healthcare staff or contaminated medical equipment.

Antifungal Agents↗
PubMed1998

Isolation of Burkholderia cepacia by enrichment.

Burkholderia cepacia is a recognised cause of respiratory failure in patients with cystic fibrosis. The value of routine use of selective enrichment broth to increase the yield of B cepacia from cystic fibrosis sputa was investigated. Two hundred sputa from 86 adult and paediatric patients were cultured onto B cepacia selective agar and also in enrichment broth. The enrichment broths were subcultured after incubation onto B cepacia selective agar. Fourteen sputa from eight patients yielded B cepacia. In all cases the isolate was recovered from the primary selective agar as well as the enrichment broth subcultures. The routine use of enrichment for cystic fibrosis sputa is of unproven benefit and increases laboratory costs.

Adolescent↗
PubMed1996

A novel simple method for quantifying bacteria from endotracheal aspirates.

A convenient dipstrip method (Bacteruritest; Mast Diagnostics) for bacterial quantification was evaluated with 42 endotracheal aspirates. For 31 specimens, the dipstrip method yielded counts within a 10-fold range of surface plate counts. Two specimens yielded counts by the dipstrip within a 100-fold range of plate counts. Six specimens yielded confluent growth at the greatest dilution tested by the dipstrip method, and counts > 10(10) cfu/ml in the surface plate method. Three specimens yielded no detectable growth by the dipstrip and surface plate counts < 10(2) cfu/ml. Dipstrips provide a cheap, convenient method for the routine quantification of the bacterial load in endotracheal aspirates.

Adult↗
PubMed1996

The occurrence of bacteraemia with skin surgery.

The need for chemoprophylaxis for bacterial endocarditis is partly dependent on the risk of bacteraemia associated with the procedure, which has not been adequately defined for skin surgery. The incidence of postoperative bacteraemia in 149 immunocompetent out-patients with non-infected lesions was 0.7% (95% CI 0.3-3.8%). Procedures included excisions, flaps, grafts and micrographically controlled surgery. Coagulase-negative staphylococcus was the most common skin isolate at the site of surgery, present in 68.5% of patients. The most effective chemoprophylaxis would be intravenous vancomycin, which is inconvenient and has an inherent risk of morbidity. Given the low incidence of bacteraemia and the disadvantages of the optimum chemoprophylaxis, surgery on non-infected lesions does not warrant prophylactic antibiotics to prevent the very low risk of bacterial endocarditis.

Adult↗
PubMed1994

Fulminant septicaemia due to Streptococcus milleri infection in a previously healthy adult.

A 59-year-old previously healthy female developed purulent pharyngitis leading rapidly to neck cellulitis, septicaemic shock and fatal cardiac arrest despite appropriate antibiotic therapy. Streptococcus milleri was isolated from a submandibular abscess, cellulitic neck tissue and blood cultures. Fulminant septicaemia due to this group of organisms is relatively uncommon and usually occurs in the immunocompromised or otherwise chronically unwell.

Anti-Bacterial Agents↗