Antibiotic sensitivity still prevails in Norwegian blood culture isolates.

We describe the antimicrobial susceptibility of bacteraemia isolates from Norway. From March 1998 to February 1999, four university hospitals covering all parts of Norway collected their first 10 isolates each month. Minimal inhibitory concentrations were determined for: Enterobacteriaceae (n=192), staphylococci (n=89) and Streptococcus pneumoniae (n=69) using the Etest. NCCLS breakpoints were used. About 20% of all blood culture isolates in Norway in this period were investigated. Compared with countries outside Scandinavia antibiotic sensitivity still prevails. Only minor differences in resistance were found between participating hospitals, between hospital departments and between hospital- and community-acquired pathogens. The prudent use of antibiotics in Norway may contribute to the fact that antibiotic resistance still remains low in the most common bacterial pathogens causing bloodstream infections.

Lipopolysaccharide heterogeneity and escape mechanisms of Neisseria meningitidis: possible consequences for vaccine development.

We wanted to compare the potential protective capacity of antibodies to meningococcal lipopolysaccharides (LPS). The frequency of occurrence and degree of expression of the epitopes recognized by murine monoclonal antibodies (MAbs) to immunotypes L3,7,9 (9-2-L379) and L8 (2-1-L8) and to the LPS inner core (216-Lc and 217-Lc), were determined among 77 consecutive Norwegian meningococcal patient isolates from 1995. The immunotype L3,7,9 was strongly expressed by 95% of the isolates, whereas L8 was weakly to moderately expressed by 9%. The inner core epitopes, were widely distributed among the serogroup B organisms, but were proved weakly expressed. The bactericidal activity of the four MAbs to various selected strains, was found to correlate positively with the quantity of the LPS epitopes recognized by these four MAbs in the bacteria. When tested in the serum bactericidal assay (SBA), often a few percent of the colonies of the inocula survived high concentrations of the MAbs. The results indicate that escape from the bactericidal action could be achieved through: (i) selection of variants not expressing the LPS-epitope of the actual MAb, (ii) a relative reduction in the density of the LPS-epitope achieved by dilution with another LPS structure or (iii) other factors, not yet understood. In conclusion, antibodies to the L3,7,9 epitope seem to be of importance for protection, whereas antibodies to the epitopes of the LPS inner core or immunotype L8, are not likely to offer protection alone. However, in order to prevent escape through alteration of the LPS pattern of the microbes, various LPS structures should probably be present in the OMV vaccine.