A real-time PCR approach to identify anthelmintic-resistant nematodes in sheep farms

Resistance to fenbendazole, ivermectin, and moxidectin was explored by a fecal egg count reduction test in four meat sheep flocks in southwestern France where anthelmintic resistance was suspected. The FECR test results of the present study confirmed the presence of benzimidazole resistance in three out of the four farms and the presence of ivermectin resistance in one flock. In addition, a suspicion of moxidectin resistance was shown in this latter farm. Both conventional morphological and molecular identifications were performed on larval cultures before and after the treatment in the studied farms. A high positive correlation was found between the number of larvae counted under binocular microscope and the number of larvae estimated by the qPCR analysis (R ² = 0.88) and a high Cohen's Kappa value (0.91) in the detection of strongylid larvae in larval cultures. According to qPCR results, Trichostrongylus species demonstrated high levels of BZ resistance and Teladorsagia circumcincta was involved in the IVM resistance in one farm. The molecular procedures used in this study have the potential to be beneficial for anthelmintic resistance surveillance in sheep industry.

The TDR Tuberculosis Strain Bank: a resource for basic science, tool development and diagnostic services

BACKGROUND

The Special Programme for Research and Training in Tropical Diseases recently launched a Mycobacterium tuberculosis strain bank (TDR-TB Strain Bank).

OBJECTIVE

To describe the TDR-TB Strain Bank, the characterisation of strains, bank management and the procedure for releasing materials.

RESULTS

The TDR-TB Strain Bank consists of 229 clinical M. tuberculosis isolates (single-colony derived cultures) plus five mycobacterial reference strains for purposes of identification. These are available as freeze-dried, viable strains or as heat-inactivated bacterial suspensions, quality controlled for purity, viability and authenticity. Isolates originated from diverse geographical settings and were selected for their resistance profiles against first- and second-line drugs. Low and high levels of resistance were determined by the minimum inhibitory concentrations of isoniazid, rifampicin, ethambutol, streptomycin, ofloxacin, kanamycin, capreomycin, ethionamide and para-aminosalicylic acid. Sequencing for drug resistance mutations was performed on the relevant sections of the rpoB, katG, inhA, embB, rpsL, rrs, gyrA and gyrB genes. Typing using lineage-defining loci of mycobacterial interspersed repetitive unit-variable number tandem repeats indicated that the most important genetic lineages were represented.

CONCLUSIONS

The TDR-TB Strain Bank is a high quality bioresource for basic science, supporting the development of new diagnostics and drug-resistant detection tools and providing reference materials for laboratory quality management programmes.

The TDR Tuberculosis Specimen Bank: a resource for diagnostic test developers

BACKGROUND

The Special Programme for Research and Training in Tropical Diseases established a specimen bank in 1999 to support the development and evaluation of new tuberculosis (TB) diagnostic tools.

OBJECTIVE

To provide a narrative of the bank's development and discuss lessons learned, the bank's limitations and potential future applications.

RESULTS

Collection sites were selected in high- and low-prevalence settings. Patients with TB symptoms, consenting to participate and to undergo human immunodeficiency virus testing were enrolled and diagnosed. Serum, sputum, saliva and urine samples were collected and sent to the bank's repositories. The bank has stocked 41,437 samples from 2524 patients at 11 sites worldwide. Ninety-five requests for specimens have been reviewed and 67 sets have been approved. Approved applicants have received sets of 20 or 200 samples. The bank allowed an evaluation of 19 commercial lateral flow tests and showed that none of them had broad global utility for TB diagnosis.

CONCLUSIONS

The establishment and development of the specimen bank have provided a wealth of experience. It is fulfilling a need to provide quality specimens, but the type and number of samples may not fulfil the demands of future end-users. Plans are underway to review the mechanisms of specimen collection and distribution to maximise their impact on product development.

High sensitivity and specificity of the Pastorex® latex agglutination test for Neisseria meningitidis serogroup A during a clinical trial in Niger

There is a great need for a rapid diagnostic test to guide vaccine choice during outbreaks of meningococcal meningitis in resource-poor countries. During a randomised clinical trial conducted during an epidemic of Neisseria meningitidis serogroup A in Niger in 2003, the sensitivity and specificity of the Pastorex latex agglutination test for this serogroup under optimal field conditions were assessed, using culture and/or PCR as the gold standard. Results from 484 samples showed a sensitivity of 88% (95% CI 85-91%) and a specificity of 93% (95% CI 90-95%). Pastorex could be a good alternative to current methods, as it can be performed in a local laboratory with rapid results and is highly specific. Sensitivity can be improved with prior microscopy where feasible. A study specifically to evaluate the Pastorex test under epidemic conditions, using laboratories with limited resources, is recommended.

Ceftriaxone as effective as long-acting chloramphenicol in short-course treatment of meningococcal meningitis during epidemics: a randomised non-inferiority study

BACKGROUND

In sub-Saharan Africa in the 1990s, more than 600,000 people had epidemic meningococcal meningitis, of whom 10% died. The current recommended treatment by WHO is short-course long-acting oily chloramphenicol. Continuation of the production of this drug is uncertain, so simple alternatives need to be found. We assessed whether the efficacy of single-dose treatment of ceftriaxone was non-inferior to that of oily chloramphenicol for epidemic meningococcal meningitis.

METHODS

In 2003, we undertook a randomised, open-label, non-inferiority trial in nine health-care facilities in Niger. Participants with suspected disease who were older than 2 months were randomly assigned to receive either chloramphenicol or ceftriaxone. Primary outcome was treatment failure (defined as death or clinical failure) at 72 h, measured with intention-to-treat and per-protocol analyses.

FINDINGS

Of 510 individuals with suspected disease, 247 received ceftriaxone, 256 received chloramphenicol, and seven were lost to follow-up. The treatment failure rate at 72 h for the intention-to-treat analysis was 9% (22 patients) for both drug groups (risk difference 0.3%, 90% CI -3.8 to 4.5). Case fatality rates and clinical failure rates were equivalent in both treatment groups (14 [6%] ceftriaxone vs 12 [5%] chloramphenicol). Results were also similar for both treatment groups in individuals with confirmed meningitis caused by Neisseria meningitidis. No adverse side-effects were reported.

INTERPRETATION

Single-dose ceftriaxone provides an alternative treatment for epidemic meningococcal meningitis--its efficacy, ease of use, and low cost favour its use. National and international health partners should consider ceftriaxone as an alternative first-line treatment to chloramphenicol for epidemic meningococcal meningitis.