Tuesday, February 22, 2011

Faster Test for Salmonella In Eggs Available

After last summers' Salmonella egg outbreak and recall, the value of accurate and quick testing methods for Salmonella should be obvious. A report today indicates progress is being made, and that a more rapid test is available. Where traditional tests might need 10 days to confirm the presence of Salmonella enteritidis (the strain commonly associated with eggs): "a collaboration between Penn’s School of Veterinary Medicine and a life science company based in California has led to the launch of a new, faster DNA-based detection kit that tests for salmonella in poultry eggs. The kit reaches accurate results in about 27 hours."

Shelley Rankin, associate professor of microbiology at Penn, was one of those responsible. Rankin says that "FDA approval of the kit was a dream more than 15 years in the making."

It does not appear, however, that the new test can assist with environmental sampling, as was done by the FDA at the Wright County/Quality Egg facility last summer once the outbreak was uncovered. "The FDA approval was for testing liquid eggs. A kit that could deliver fast and accurate results for samples taken from the environment where the birds are kept could help producers detect salmonella even sooner."

Monday, February 7, 2011

PCR-Mass Spec Rapid Method Used To Identify Plague in Afghanistan

Today, at the American Society for Microbiology Conference on Biodefense and Emerging Diseases, scientists from Abbott Molecular presented data showing the unique power of the company's Ibis technology to identify and further characterize unknown disease-causing pathogens to help aid in the bioforensic analysis of pandemic outbreaks.

In a presentation at the conference, Tim Motley, principal scientist, Ibis Biosciences, a subsidiary of Abbott, reported on genotypic characterization of Yersina pestis after a severe outbreak of an unknown disease in Afghanistan's Nimorz Province in December 2007. Eighty-three people experienced severe fever, vomiting and diarrhea, and 17 died. All had consumed camel meat. Due to the gastrointestinal symptoms and disease severity, anthrax was suspected.
Blood from a patient sample and several camel tissue specimens were analyzed using the Ibis T5000 biosensor, a precursor to the PLEX-ID™ system developed and marketed by Abbott. The analysis showed both the blood and camel tissue specimens tested positive for Yersina pestis, the causative agent for plague. This was the first reported case of plague in Afghanistan. Other test methods, including culture, had failed to identify the causative organism.

"With the PLEX-ID technology, we were able to genetically characterize the strain, identify its unique genetic structure and develop a microbial forensic marker that could be used to identify this strain should future outbreaks occur," said Motley. He added that the ability of PLEX-ID to combine polymerase chain reaction (PCR) and electrospray ionization mass spectrometry allows laboratories to identify an unknown organism and determine its specific genotype.

Motley explained that the Afghanistan case shows the broad applicability of PLEX-ID technology for use in identifying and characterizing infectious agents before they become widespread.

Tuesday, February 1, 2011

Biosensor May ID Antibiotic Susceptibility of Bacteria

A biosensor-based antimicrobial susceptibility test (b-AST) may enable the rapid determination of antibiotic susceptibility of urinary tract pathogens, according to a study published in the January issue of The Journal of Urology.

Kathleen E. Mach, from the Stanford University School of Medicine in California, and colleagues cultured bacteria from 252 urine samples from patients at the Veterans Affairs Palo Alto Health Care System. Bacterial growth with and without antibiotics was monitored by measuring viable counts, and by using a direct biosensor quantitation of bacterial 16S rRNA. Pathogen identification and antibiotic susceptibility were determined directly from patient samples and compared between the b-AST and standard microbiological analysis.

The researchers established that the quantitation of 16S rRNA can be used to measure bacterial growth directly from patient urine samples. In 368 pathogen-antibiotic tests, the b-AST was 94 percent accurate compared to standard microbiological analysis, and provided culture and susceptibility information within 3.5 hours. "b-AST uses an electrochemical biosensor to detect differential 16S rRNA levels after short-term pathogen culture in the presence and absence of antibiotics. In a pilot clinical validation study using infected urine samples the overall agreement of b-AST with the standard clinical microbiology AST was 94 percent," the authors write.