Biomedical subjects

Brigid Lucey

Publications and source records attributed to Brigid Lucey.

4 recordsLinked to original sources

PubMed2006

Comparison of three stool antigen assays with the 13C- urea breath test for the primary diagnosis of Helicobacter pylori infection and monitoring treatment outcome.

BACKGROUND: The urea breath test (UBT) is the gold-standard non-invasive test for the detection of Helicobacter pylori infection, however, the lack of availability of the UBT due to the high cost of the test, and in particular the need for expensive analytical instrumentation, limits the usefulness of this method. Stool antigen assays may offer an alternative non-invasive method for the diagnosis of infection. OBJECTIVE: To compare the accuracy of three stool antigen assays (HpSA, IDEIA HpStAR, and ImmunoCard STAT) against the UBT for the primary diagnosis of H. pylori infection and for monitoring treatment outcome. METHODS: A total of 102 patients attending two gastroenterology day-case clinics for the investigation of dyspepsia were included. Each patient provided breath and stool samples for analysis. Patients who tested positive for H. pylori by the validated UBT were prescribed triple therapy and invited to return for repeat breath and stool sample analysis 6 weeks post-treatment. RESULTS: Of the 102 patients tested, 48 were diagnosed with H. pylori infection by the UBT. The HpSA assay interpreted 38 of these as positive (79% sensitive). Of the 54 UBT-negative patients the HpSA assay interpreted all 54 as negative (100% specific). The IDEIA HpStAR assay correctly identified 44 patients as positive (92% sensitive) and 50 as negative (92.5% specific). The ImmunoCard STAT assay interpreted 38 patients as positive (79% sensitive) and 52 as negative (96.3% specific). CONCLUSION: The findings indicate that the IDEIA HpStAR stool antigen kit is the most accurate assay of the three assays evaluated, and possibly represents a viable alternative to the UBT for the primary diagnosis of H. pylori infection and for monitoring treatment outcome.

Adult↗

PubMed2004

Molecular characterization of class 1 integrons from Irish thermophilic Campylobacter spp.

OBJECTIVES: In this study a large random collection (n = 378) of Irish thermophilic Campylobacter isolates were investigated for the presence of integrons, genetic elements associated with the dissemination of antimicrobial resistance. METHODS: Purified genomic DNA from each isolate was analysed by PCR for the presence of class 1 integrons. Four gene cassette-associated amplicons were completely characterized. RESULTS: Sixty-two of the isolates possessed a complete class 1 integron with a recombined gene cassette located within a 1.0 kb amplicon containing an aadA2 gene. This cassette was present in both Campylobacter jejuni and Campylobacter coli isolates and following sequence analysis was shown to be similar to sequences recently reported in Salmonella enterica Hadar and on an 85 kb plasmid conferring quinolone resistance in Escherichia coli. CONCLUSIONS: Aminoglycoside aadA2-encoding class 1 integrons were identified among unrelated Campylobacter spp. Amino acid sequence comparisons revealed identical structures in both Salmonella and E. coli. The presence of class 1 integrons in Campylobacter spp. may be significant should these organisms enter the food chain and especially when antimicrobial treatment for severe infections is being considered.

Animals↗

PubMed2004

Molecular-based identification and typing of Campylobacter jejuni and C. coli.

Thermophilic Campylobacter spp., mainly Campylobacter jejuni and to a lesser extent C. coli are recognized as the most common bacteriological causes of gastroenteritis in humans. As enteric infection with Campylobacter organisms cannot be distinguished from that caused by other enteric pathogens, a definitive diagnosis can only be made by isolating or detecting the organism from the feces. The epidemiology of Campylobacter enteritis has been complicated by the ubiquitous nature of the organism (commonly found as a commensal in the intestines of domestic animals, in milk, and in water). Furthermore, identification is carried out only to genus level by most clinical laboratories. Because of the biochemical similarity known to exist between C. jejuni and C. coli, the hippurate hydrolysis test is often used as the only phenotypic test capable of differentiating the two species. This test, however, has some acknowledged technical limitations and is dependent on inoculum size; results can be difficult to interpret accurately. Furthermore, almost all C. jejuni isolates possess the hippuricase gene, fewer C. jejuni isolates express the hippuricase gene. For this reason, certain polymerase chain reaction (PCR)-based species identification methods, for both C. jejuni and C. coli, and for the other thermophilic species, provide more reliable identification; they also help to highlight mixed species cultures, should they occur. However, even with these methods, false negatives or nonspecifically amplified product(s) can occur in a minority of isolates tested owing to genomic anomalies. Thus a second molecular identification method may be required in these circumstances. Gonzalez et al. developed a species-specific PCR assay for the identification of C. jejuni and C. coli based on the ceuE gene, which is involved in siderophore transport. Using this method two primer sets are employed in separate PCR amplification reactions. Another method, developed by Eyers et al., performs PCR amplification of 23S rRNA gene fragments, based on regions specific for C. jejuni, C. coli, C. lari, and C. upsaliensis. In addition, Hani and Chan developed a PCR assay that detected and amplified the hippuricase gene. This molecular approach may offer a more reliable means of identifying C. jejuni strains compared with the phenotypic hippurate hydrolysis test alone.

Bacterial Typing Techniques↗

PubMedDate not supplied

Campylobacter.

Species within the genus, Campylobacter, have emerged over the last three decades as significant clinical pathogens, particularly of human public health concern, where the majority of acute bacterial enteritis in the Western world is due to these organisms. Of particular concern are the species, C. jejuni and C. coli, which are responsible for most of these gastrointestinal-related infections. Although these organisms have already emerged as causative agents of zoonoses, several aspects of their epidemiology and pathophysiology are only beginning to emerge. Trends in increasing antibiotic resistance are beginning to emerge with oral antibiotics, which may be the drug of choice for when it is necessary to intervene chemotherapeutically. This review wishes to examine (i) emerging clinical aspects of the disease, such as Guillain Barre syndrome (GBS), (ii) the association between these organisms and poultry as a natural host, (iii) environmental aspects of Campylobacter epidemiology, (iv) the emergence of atypical campylobacters (v) emerging trends in antibiotic resistance, (vi) adoption of modern methods for the detection of campylobacters.

Animals↗