Seminested polymerase chain reaction (PCR) for detecting Helicobacter pylori DNA in carotid atheromas.

A polymerase chain reaction (PCR) method for the detection of the glmM gene, selected as Helicobacter pylori target sequence, was improved. While performing pathogenicity island cagA gene detection to discriminate pathogenic strains in atherosclerotic carotid samples, several cagA-positive but glmM-negative samples were found. Polymorphisms present in the region amplified in the nested PCR reaction could explain this result; primers were therefore designed to perform a seminested reaction; this modification optimized sensitivity while maintaining specificity. A real-time PCR for Helicobacter DNA detection was also setup. The combination of all 4 PCR reactions detected 83% of H. pylori DNA-positive samples in atherosclerotic carotid tissue, 64% of which were cagA gene positive.     

Physical mapping of the Coxiella burnetii genome.

Coxiella burnetii isolates from different genomic groups contain restriction fragment polymorphisms that were easily distinguishable using pulsed field gradient electrophoresis (PFGE). Conversely, isolates that belong to the same genomic group yield identical patterns indicating that PFGE can be used to identify the genomic grouping of new C. burnetii isolates. Intact C. burnetii cells were embedded in agarose and lysed in situ. The genomic DNA was digested with low-frequency cutting restriction endonucleases, and subjected to PFGE analysis. NotI and SfiI cut C. burnetii DNA least often and produced the largest fragments. ApaI, MluI, SalI, XbaI or XhoI produced only small DNA fragments (+/- 50 kbp). When PFGE was used to analyse C. burnetii genomes for the presence of plasmid-related sequences, all the plasmid sequences in Nine Mile and Priscilla were associated with their 36 kbp or 39 kbp plasmid bands, respectively. If these isolates contained plasmid sequences which had integrated into their chromosomes those sequences would have been visible as additional bands. These same studies also showed that plasmid sequences in the plasmidless-Ko isolate were completely contained within two NotI fragments, indicating that the integrated plasmid is localized to a concise region of the C. burnetii genome. Since it is difficult to conduct genetic analyses of obligate intracellular parasites using standard techniques, a physical map is being developed using PFGE. In addition to providing a means for determining gene loci, the physical maps provide a means for comparing genetic organization among the different strains of C. burnetii.     

Early recognition of newborn goat kids by their mother: II. Auditory recognition and evidence of an individual acoustic signature in the neonate

The vocal recognition of newborn kids by their mother at 2 days postpartum and the possible existence of interindividual differences in the voice structure of newborn kids were investigated in two separate studies. The ability of goats to discriminate between the bleats of their own versus an alien kid was tested at 2 days postpartum in mothers being prevented access to visual and olfactory cues from the young. Goats spent significantly more time on the side of the enclosure from which their own kid was bleating, looked in its direction for longer, and responded more frequently to the bleats of their own than to those of the alien kid (p < 0.05). In the second study, the sonograms of 13 kids, studied from Days 1 to 5, showed significant interindividual differences for the five variables taken into account and on each of the 5 days (duration of bleat, fundamental frequency, peak frequency, and numbers of segments and of harmonics). The potential for individual coding ranged between 1.1 and 4.1, indicating that for some variables variations between individuals were greater than intraindividual variations. Furthermore, when considering the five parameters together, the discriminating scores showed an average of 95% in the 78 combinations of any 2 kids for any given day. Finally, some significant intraindividual differences also were found between days, suggesting ontogenic changes in the characteristics of the kid's voice in early life. Therefore, mother goats are likely to recognize the vocalizations of their 48-hr-old kids, as they show sufficient interindividual variability to allow the existence of individual vocal signatures, even though some of the characteristics of the bleats change rapidly over time.     

Six-month multicenter study on invasive infections due to Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis in Argentina

During a 6-month period, 95 invasive infections due to Streptococcus pyogenes and group C or group G Streptococcus dysgalactiae subsp. equisimilis were recorded from 40 centers of 16 cities in Argentina. We describe here epidemiologic data available for 55 and 19 patients, respectively, associated with invasive infections due to S. pyogenes and S. dysgalactiae subsp. equisimilis. The associated isolates and 58 additional pharyngeal isolates were genotyped and subjected to serologic and/or antibiotic susceptibility testing. Group A streptococcal emm type distribution and strain association with toxic shock appeared to differ somewhat from results found within the United States; however, serologic characterization and sof sequence typing suggested that emm types found in both countries are reflective of shared clonal types.     

Presence of pili on the surface of Francisella tularensis

Francisella tularensis is a highly infectious gram-negative bacterium with potential for use as a bioweapon. Analysis of the F. tularensis live vaccine strain (LVS) ultrastructure by electron microscopy revealed the presence of long, thin fibers, similar in appearance to type 4 pili. The highly virulent F. tularensis Schu S4 strain was found to contain type 4 pilus genes, and we confirmed that these genes are present and expressed in the LVS.