Analysis of Bordetella pertussis clinical isolates circulating in European countries during the period 1998-2012.

Despite more than 50 years of vaccination, pertussis is still an endemic disease, with regular epidemic outbreaks. With the exception of Poland, European countries have replaced whole-cell vaccines (WCVs) by acellular vaccines (ACVs) in the 1990s. Worldwide, antigenic divergence in vaccine antigens has been found between vaccine strains and circulating strains.

Investigations into the emergence of pertactin-deficient Bordetella pertussis isolates in six European countries, 1996 to 2012.

Pathogen adaptation has been proposed to contribute to the resurgence of pertussis. A striking recent example is the emergence of isolates deficient in the vaccine component pertactin (Prn). This study explores the emergence of such Prn-deficient isolates in six European countries.

Pertussis disease burden in the household: how to protect young infants.

Background: We conducted a population-based, nation-wide, prospective study to identify who introduced pertussis into the household of infants aged 6 months admitted to the hospital for pertussis in the Netherlands.

Methods: During the period 2006-2008, a total of 560 household contacts of 164 hospitalized infants were tested by polymerase chain reaction, culture, and serological examination to establish Bordetella pertussis infection. Clinical symptoms and vaccination history were obtained by a questionnaire submitted during sample collection and 4-6 weeks afterwards.

Experimental studies on the infectivity of non-culturable forms of Campylobacter spp. in chicks and mice.

The significance of non-culturable forms of Campylobacter spp., especially with regard to the epidemiology of this organism in poultry flocks, was explored. Two different experiments were conducted to produce non-culturable Campylobacter spp.

Use of the polymerase chain reaction for direct detection of Listeria monocytogenes in soft cheese.

The polymerase chain reaction (PCR) amplification technique was investigated as a tool for direct detection of Listeria monocytogenes in soft cheeses. Different sets of oligonucleotide primers were used, and parts of the L. monocytogenes Dth 18-gene could be amplified specifically when either a plasmid vector carrying the cloned gene or chromosomal DNA was used a template.

The use of DNA probes for confirming enterotoxin production by Staphylococcus aureus and micrococci.

DNA-DNA colony hybridization was employed to evaluate the results obtained by different immunological methods for detection of staphylococcal enterotoxin. Staphylococcus aureus strains tested for staphylococcal enterotoxin production by immuno-assays and micrococci not previously tested for staphylococcal enterotoxin production were examined for presence of the genes encoding for staphylococcal enterotoxin A, B, C and E by using three corresponding DNA probes. The staphylococcal enterotoxin A probe also detected staphylococcal enterotoxin E gene because of 100% homology.

Detection of Mold in Food by Enzyme-Linked Immunosorbent Assay.

Evaluation of the enzyme-linked immunosorbent assay (ELISA) for detecting a mold-specific, heat-stable and water-soluble antigen demonstrated the potential of the method for detecting molds in food products. The mold antigen, as produced by Penicillium spp. and Aspergillus spp.

Evaluation of the ELISA as tool in diagnosing Clostridium perfringens enterotoxins.

Detecting Clostridium perfringens enterotoxin (CPE) using the enzyme linked linked immunosorbent assay (ELISA) was evaluated as a tool for diagnosing enterotoxicosis caused by C. perfringens. This method was assessed using a number of different food poisoning outbreaks with possible C.

The Salt Crystal Liquefaction Test - A Simple Method for Testing the Water Activity of Foods.

A simple method for testing the water activity (a) of foods has been developed. The test can be used to check the a of products which must comply with required a standards. The test is based on the property of salt crystals to attract water vapor and to liquefy when they are placed in a jar containing a product with an a above the specific a of the salt.