Bacterial pathogens detection

Bacterial pathogens are relatively large targets (> 1pm) and therefore, their presence can be detected directly with an optional amplification by secondary antibodies (sandwich assay). Examples of foodbome bacterial pathogens detected by SPR biosensors include Escherichia coli (detection limit 5x10 cfii/ml " " ), Listeria monocytogenes (detection limit 1 O cfii/ml " ) and Salmonella enteritidis (detection limit lO cfii/ml" ). 

Higgins, J.A., S. Nasarabadi, J.S. Karns, D.R. Shelton, M. Cooper, A. Gbakima, and R.P. Koopman. A handheld real time thermal cycler for bacterial pathogen detection. Biosens Bioelectron. 2003, 18(9), 1115-1123... 

Mai JDH, Gaster RS, Wu A, Gu W, Mach K, Liao JC (2007) A microfluidic system for rapid bacterial pathogen detection. In Proceedings of the 7th IEEE international conference on nanotechnology, IEEE, Hong Kong, 2-5 Aug 2007, pp 1330-1334... 

Call, D. R. Borucki, M. K. Loge, F. J. Detection of bacterial pathogens in environmental samples using DNA microarrays. J. Microbiol. Meth. 2003, 53, 235-243. 

Events involving deliberate or accidental distribution of bacterial pathogens into our everyday environment have clearly defined the need for a sensitive, specific, and rapid method of bacterial detection. Bioterrorism was first introduced in the United States in 1984 with the Salmonella typhimurium attack in The Dalles, Oregon, by a cult group attempting to affect a local election.1 As a result of this act 751 people contracted salmonellosis, which totally overwhelmed the hospitals and medical clinics with patients. Later our society became keenly aware of the potential of bioterrorism during the last four months of 2001 when Bacillus anthracis (anthrax) spores were sent through the US mail in an envelope to several locations. These events had... 

The objective of mastitis treatments is to cure the infected udders from the infection, but cure is defined in very different ways. For example, in economic terms, the farmer needs to achieve a level of udder health that allows expected milk yields and quality parameters specified by processors/ national regulations to be achieved. On the other hand, cure with respect to antibiotic treatments, is often defined in terms of absence of bacterial pathogens in milk (bacterial cure), with the proportion of cows without detectable pathogen presence following treatment being defined as the bacterial cure rate (BCR). The main problem with using BCR as the main indicator of cure is that it was frequently shown to include a proportion of cows with drastically elevated SCC values (indicative of sub-clinical mastitis) after treatment, but without clinical (sensory) symptoms. 

Large analytes targeted by affinity biosensor technology include bacterial pathogens such as Escherichia coli, Salmonella enteritidis, and Listeria monocytogenes. Salmonella enteritidis and Listeria monocytogenes were detected by an SPR sensor at concentrations down to 106 cfu/ml27. 

M.A. Hahn, J.S. Tabb, and T.D. Krauss, Detection of single bacterial pathogens with semiconductor quantum dots. Anal. Chem. 77, 4861 1869 (2005). 

Rapid methods to detect pathogenic bacteria in food products are important alternatives to laborious and time-consiuning culture procedures. Many investigators have pubUshed papers on the use of electrochemical immunosensors for the identification and quantification of bacterial pathogens Escherichia coli 0157, Staphylococcus aureus, and Salmonella spp., which are common contaminants of food or water. 

Tenover FC (2007) Rapid detection and identification of bacterial pathogens using novel molecular technologies infection control and beyond. CUn Infect Dis 44 418 23 Tenover FC, Vaughn RR, McDougal LK, Fosheim GE, McGowan JE Jr (2007) Multiple-locus variable-number tandem-repeat assay analysis of methidllin-resistant Staphylococcus aureus strains. J CUn Microbiol 45 2215-2219... 

Table 8 summarizes PCR applications in detecting bacterial pathogens. Most of these studies concern simple detection of the organism rather than diagnosis and await standardized procedures, simplified sample preparation methods, and colorimetric detection formats before they will be practical for clinical laboratories. 

---