Phylogenetic variation of Aggregatibacter actinomycetemcomitans serotype e reveals an aberrant distinct evolutionary stable lineage.

The periodontal pathogen Aggregatibacter actinomycetemcomitans that comprises six serotypes (a-f), is often identified by PCR-based techniques targeting the 16S rRNA gene. In this study, 16S rRNA gene sequence analysis revealed an aberrant cluster of 19 strains within serotype e, denoted as serotype e'. The 16S rRNA gene sequence similarities found between serotype e' strains ranged from 99.7% to 100.0%, whereas 96.8-97.5% sequence similarity was obtained with members of the other serotypes, indicating that the serotype e' strains might not be true members of A. actinomycetemcomitans. However, DNA-DNA hybridizations between a representative serotype e' strain and representative strains of serotypes b, d and e of A. actinomycetemcomitans revealed 68-75% DNA-DNA relatedness, demonstrating that the serotype e' strains do belong to the species A. actinomycetemcomitans. AFLP analysis of 33 A. actinomycetemcomitans strains, representing all serotypes (a-f), but mainly serotype e' strains, showed that the latter form a distinct cluster, demonstrating that these strains are also closely related on the whole genome level. Moreover, the serotype e' strains were unable to ferment starch and glycogen in contrast to almost all other A. actinomycetemcomitans strains tested. Overall, the data obtained in this study suggest that the serotype e' strains form an evolutionary relatively stable distinct subgroup within A. actinomycetemcomitans.

Characterisation of carbapenem-resistant Acinetobacter baumannii outbreak strains producing OXA-58 in Turkey.

The aim of this study was to characterise the molecular epidemiology and mechanisms of carbapenem resistance of nosocomial Acinetobacter baumannii isolates in a new university hospital in Turkey. A total of 145 carbapenem-resistant A. baumannii (CRAB) isolates were collected during the period 2003-2006. All isolates were typed by amplified fragment length polymorphism (AFLP) analysis. AFLP analysis showed three predominant clusters consisting of 72, 20 and 12 clinical strains as well as some smaller clusters and 23 unique strains. The three main clonal AFLP types corresponded to three major antibiotic susceptibility patterns. One environmental isolate was found related to the major outbreak clone. The reference type strains of European clones I, II and III were also typed by AFLP and analysed for clonal similarity. Polymerase chain reaction (PCR) analysis of different carbapenem resistance genes showed that strains from each of the three main clusters as well as 79% of the remaining strains harboured the bla(OXA-58) gene. No genes encoding the metallo-beta-lactamases GIM-1, SIM-1, SPM-1, IMP-like and VIM-like or the oxacillinases OXA-24-like and OXA-23-like were detected. In conclusion, multiple clones of CRAB strains producing OXA-58-type oxacillinase were responsible for a sustained CRAB outbreak occurring in a hospital in Turkey. These isolates were not associated with A. baumannii strains of the major European clones I, II or III.

Clonal stability of Porphyromonas gingivalis in untreated periodontitis.

OBJECTIVES: The objective of the present investigation was to study the clonal stability of Porphyromonas gingivalis in a population of Indonesian subjects, deprived of dental care and with varying degrees of periodontitis over a period of 8 years. MATERIAL AND METHODS: In 1994, 105 subjects and in 2002, 103 subjects were P. gingivalis culture positive. Multiple isolates from each of these subjects were used for amplified fragment length polymorphism (AFLP) typing. RESULTS: Sixty-six individuals were P. gingivalis culture positive at both time points. In 31 subjects (47%) an exact identical P. gingivalis genotype distribution was found in 1994 and in 2002. In 26 of these subjects one genotype, in eight subjects two identical genotypes were found at both time points. In 70% of the subjects at least one P. gingivalis genotype was found in 1994 and 2002, whereas other genotypes were either newly detected or were no longer detectable. Identical genotypes were found in 26% of the sibships. Clonal stability in siblings was 39%. Horizontal transmission of P. gingivalis was only found in 2002 and was low (11%). In total, 56 P. gingivalis genotypes were identified in 1994 and 61 in 2002. Twenty-four appeared unique, whereas other genotypes were found in multiple subjects within as well as without families. One genotype occurred in 11 different subjects. CONCLUSIONS: The clonal stability of P. gingivalis under natural conditions is high. Complete different genotype distribution was found in only 27% of the subjects. Transmission of P. gingivalis occurred frequently among siblings but not among spouses.

Extended-spectrum-beta-lactamase production in a Salmonella enterica serotype Typhi strain from the Philippines.

A Salmonella enterica serotype Typhi strain was cultured from blood and fecal samples from a 54-year-old man with fever and diarrhea. He had returned from travel to the Philippines a few days earlier. Phenotypic and genotypic analysis confirmed the production of the SHV-12 extended-spectrum beta-lactamase.