Relationship between nosocomial Acinetobacter species occurring in two geographical areas (Greece and the UK).

Fifty-two isolates of Acinetobacter spp. obtained from three Greek and one UK hospital, were studied using partial 16 S ribosomal DNA sequence analysis, repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR) mediated fingerprinting and DNA macro-restriction analysis. The aim was twofold: first, to discern the major differences in the population of Acinetobacter spp. between the two countries. Second, to compare a simple PCR-based typing scheme with pulsed-field gel electrophoresis (PFGE). The multi-resistant Greek isolates were within DNA groups 2 and TU13, and clustered into three types both by REP-PCR and PFGE. By contrast, the more susceptible Oxford isolates were heterogeneous on 16 S RNA sequence analysis and distinguishable on typing. The need for studies that elucidate the phylogeny of Acinetobacter spp. inside and outside hospitals are important, as this will help clarify the relationship between organisms that are increasingly recognized as causes of severe infections.

A molecular analysis of Greek and UK Haemophilus influenzae conjugative resistance plasmids.

Antibiotic resistance in Haemophilus influenzae has been associated with the presence of large, chromosomally integrated, conjugative plasmids. The plasmids of 10 beta-lactamase-positive, ampicillin-resistant strains, two from the UK and eight from Greece, were investigated. Plasmids were detected and isolated after transfer to a rec-deficient recipient. Purified whole plasmid was used as probe. In addition a 12 kb PstI fragment containing the putative point of recircularization in one plasmid, p1056, was cloned and used as a probe. All plasmids shared a high degree of sequence homology suggesting that plasmids of diverse geographical origin are highly related. All plasmids also shared sequence homology with the 12 kb PstI fragment containing the point of recircularization, suggesting that the sequences involved in excision and recircularization are conserved.

Molecular epidemiology of unrelated clusters of multiresistant strains of Haemophilus influenzae.

Three epidemiologically unrelated clusters of Haemophilus influenzae resistant to ampicillin, chloramphenicol, and tetracycline were studied. The biotypes and cell-envelope protein patterns were determined for 17 nonencapsulated strains, 6 from Dundee and 11 from Cheltenham, and for 6 type b encapsulated strains from Guildford. After mobilization by conjugation, large 32- to 36-MDa plasmids were purified from all the strains. The restriction fragment patterns of the plasmids were determined by ethidium bromide staining of digested purified plasmid or by Southern hybridization of digested total cellular DNA of the parent strains, probed with purified plasmid. Evidence is presented for a chromosomal location of the plasmids in the parent strains, the spread in nature of a plasmid between distinguishable strains of H. influenzae, the person-to-person spread of a strain within a cluster, and a high degree of sequence homology between distinguishable plasmids, implying their close relatedness.