Lars Bevanger

Candidemia in Norway (1991 to 2003): Results from a Nationwide Study

ABSTRACT A long-term, nationwide prospective candidemia study has been ongoing in Norway since 1991. All medical microbiological laboratories in the country have participated. During the period 1991 to 2003 a total of 1,393 episodes of candidemia occurred in 1,348 patients. The incidence of candidemia episodes per 100,000 inhabitants increased from approximately 2 episodes in the early 1990s to 3 episodes in 2001 to 2003. The average annual incidences varied markedly between the age groups. The incidence was high in patients aged <1 year and in patients aged ≥70 years. In patients ≥80 years of age, the incidence has increased during the last 3 years from an annual average of 6.5 to 15.6 cases/100,000 inhabitants in 2003. Four Candida species (C. albicans [70%], C. glabrata [13%], C. tropicalis [7%], and C. parapsilosis [6%]) accounted for 95.5% of the isolates. The species distribution has been constant during the 13-year study period. The distribution of the most important species varied with the age of the patient. In patients <1 year of age, the majority of episodes were caused by C. albicans (91%). The occurrence of C. glabrata increased with age. In patients ≥80 years of age, approximately 1/3 of all episodes were due to this species. All C. albicans strains were susceptible to fluconazole. The percentage of yeast isolates with decreased susceptibility to fluconazole (MICs ≥ 16 μg/ml) was 10.7% during the first period of this study (1991 to 1996) and 11.7% during the second period (1997 to 2003).

Identification of Virulence Genes Linked with Diarrhea Due to Atypical Enteropathogenic Escherichia coli by DNA Microarray Analysis and PCR

ABSTRACT The role of atypical enteropathogenic Escherichia coli (EPEC) in childhood diarrhea is controversial. The aim of the present study was to search for genes linked with diarrhea in atypical EPEC strains from a case-control study among Norwegian children. Using DNA microarray analysis, genomic DNAs from strains isolated from children with (n = 37) and without (n = 20) diarrhea were hybridized against 242 different oligonucleotide probes specific for 182 virulence genes or markers from all known E. coli pathotypes. PCR was performed to test the strains for seven putative virulence genes not included in the microarray panel. The OI-122 gene efa1/lifA was the gene with the strongest statistical association with diarrhea (P = 0.0008). Other OI-122 genes (set/ent, nleB, and nleE) and genes with other locations (lpfA, paa, ehxA, and ureD) were also associated with diarrheal disease. The phylogenetic marker gene yjaA was negatively associated with diarrhea (P = 0.0004). Atypical EPEC strains could be classified in two main virulence groups based on their content of OI-122, lpfA, and yjaA genes. Among children with diarrhea, atypical EPEC isolates belonging to virulence group I (OI-122 and lpfA positive, yjaA negative) were the most common, while the majority of isolates from healthy children were classified as virulence group II strains (OI-122 negative, lpfA and yjaA positive; P < 0.001). In conclusion, using DNA microarray analysis to determine the virulence gene profile of atypical EPEC isolates, several genes were found to be significantly associated with diarrhea. Based on their composition of virulence genes, the majority of strains could be classified in two virulence groups, of which one was seen mainly in children with diarrhea.

A Streptococcus agalactiae R protein analysed by polyclonal and monoclonal antibodies

Unexpected cross‐reactivity between two Streptococcus agalactiae (GBS) isolates formed the basis for purification of a GBS protein called the Ra antigen, and raising of murine monoclonal antibody (MAb) against Ra. The Ra protein was resistant to trypsin digestion, susceptible to pepsin digestion, formed a ladder‐like pattern of lines with a periodicity of ˜8 kD on immunoblotting, was surface localized in GBS strains, and was variably expressed by GBS. These characteristics provided evidence that the Ra antigen belonged to the R proteins of GBS. By testing of reference GBS isolates and antiserum, including an anti‐R4 protein serum, cross‐reactivity was recorded consistent with the assumption that Ra is a R4 protein. The Ra/R4 protein also showed cross‐reactivity with a previously described GBS protein called protein Rib (J. Exp. Med. 177: 1593–1603, 1993). Several characteristics of the Ra/R4 protein were similar to those of the GBS protein cα, but the two proteins showed no cross‐reactivity. The anti‐Ra/R4 MAb has proved useful in serosubtype determination of GBS of known serotype and should be a valuable tool for studying the immunobiological function of antibodies targetting the surface‐localized Ra/R4 protein.

Low prevalence of Bartonella henselae infections in Norwegian domestic and feral cats.

Bartonella henselae is the causative agent of cat scratch disease (CSD). This clinical entity is very rarely encountered in human medical practice in Norway. B. henselae infections including bacteraemia in cats have been frequently reported. The objective of the present study was to investigate the seroprevalence rate and the degree of B. henselae bacteraemia in Norwegian domestic and feral cats. One hundred cats investigated at a small animal veterinary practice in the middle of Norway were included in the study. Blood collected in Isolator blood‐lysis tubes and lysates of erythrocytes after freezing and thawing were cultured. PCR analysis of whole blood was also performed. Serology was performed by indirect fluorescence assay (IFA) and enzyme immunoassay (EIA) using immobilised B. henselae Houston‐1 strain as antigen. None of the 100 cats investigated was found to be bacteraemic. All 100 cats were seronegative when analysed by IFA; one cat was positive by EIA. The discrepancy between IFA and EIA of this particular cat is probably due to cross‐reactive antibodies. Contrary to findings reported from several geographic regions, B. henselae infections in Norwegian cats appear to be virtually absent. This in turn may explain why CSD has not been reported in human medical practice in Norway.

Streptococcus Agalactiae β Gene And Gene Product Variations

Streptococcus agalactiae (group B streptococci; GBS) are serotyped on the basis of the capsular polysaccharide antigens and subtyped on the basis of the strain-variable and surface-localised c proteins c α , c β , and R proteins. This study compared c β protein detection and the polymerase chain reaction (PCR) for β gene detection, by examining 50 clinical GBS strains. The c β protein was detected by antibody-based immunofluorescence in a GBS whole-cell assay and Western blotting by probing with the anti-c β antibody or human IgA. Absorption experiments were performed to test for surface-anchoring of c β ; and bacterial supernates were examined to test for c β production. Primers for the PCR target regions resulted in a 620-bp product that included β gene-encoding IgA-binding domains. The results demonstrated four categories of GBS with respect to the β gene and the c β protein: (1) strains (16 of 50) that harboured the β gene and regularly expressed normal surface-localised c β with a M r of 120 kDa; (2) strains (5 of 50) that harboured the gene but did not express the protein; (3) strains (2 of 50) that harboured the gene but expressed a c β that was not surface-localised and had reduced M r ; (4) strains (27 of 50) without β gene and c β expression. One strain amongst the third group generated a PCR product of 1330 bp. These results demonstrate considerable strain variability of the β gene of GBS and of its product the c β protein.

Moraxella lacunata isolated from epidemic conjunctivitis among teen-aged females

Abstract. An epidemic follicular conjunctivitis affecting teen‐aged females has been studied. Moraxella lacunata was isolated from 11% of the patients, a frequency far above the rate found in other types of chronic conjunctivitis. The condition is suggested to be the chronic follicular conjunctivitis (Axenfeld) due to Moraxella lacunata.

Characterization of the a antigen of the c proteins of group B streptococci (GBS) using a murine monoclonal antibody

A murine monoclonal antibody raised against the a antigen of the group B streptococcal c proteins was analysed by immunofluorescence and whole‐cell ELISA against a collection of 22 c protein‐producing GBS. All the strains showing fluorescence and reactivity in ELISA turned out to be a antigen‐carrying strains as defined by polyclonal rabbit antisera, while none of the strains producing only the p antigen was positive. Western blot analyses of the a antigen released into the culture medium of growing bacteria suggest that the a antigen is present as distinct proteins of variable molecular weights. The upper limit of the molecular weights varies considerably from one strain to another, from approximately 200 kD to 70 kD. With all strains, the bands seen by the MAb occurred at regularly spaced intervals of about 10 kD throughout the gel. Some strains gave rise to 15–16 bands, while others gave rise to only one or two bands. The present investigation suggests that α antigens include several, probably identical, repeating subunits of approximately 10 kD. The epitope recognized by the MAb seems to be located on a 10‐kD fragment, and in addition, it appears to be surface located, making the MAb a suitable tool in serodiagnostic work.

Peritoneal Dialysis-Associated Peritonitis Caused by Dermabacter hominis

ABSTRACT Dermabacter hominis was the cause of a peritoneal dialysis-associated peritonitis. D. hominis was identified by phenotypic criteria and by sequencing the 16S rRNA gene. Clinical cure was achieved with cefuroxime treatment despite the isolates reduced susceptibility to this drug (MIC, 12 mg/liter) on in vitro testing. The successful treatment was probably due to the high concentrations attained by intraperitoneal administration of the drug.

Posttrabeculectomy Endophthalmitis Caused by Moraxella nonliquefaciens

Moraxella nonliquefaciens, a commensal organism of the upper respiratory tract, is generally considered to have low pathogenic potential. We report here two cases of severe endophthalmitis occurring 9 years and 2 months after glaucoma filtration surgery, respectively. Apart from sulfonamide, very low MICs were recorded for several antibiotics tested. Identification was based on phenotypic characteristics in combination with sequencing of the 16S rRNA gene.

Distribution and expression of bca, the gene encoding the c alpha protein, by Streptococcus agalactiae.

A total of 52 clinical isolates of group B streptococci (GBS) was tested for expression of the c protein c(alpha) by a fluorescent antibody test (FAT) and by PCR amplification of a 202-bp stretch within the repeat unit of the bca gene encoding the c(alpha) protein. The strains were categorised as follows: c(alpha) FAT positive and PCR positive with amplification products of multiple sizes (category A, n = 12); FAT negative and with PCR products of multiple sizes (category B, n = 11); FAT negative and with a single PCR product of c. 200 bp (category C, n = 5); negative in both tests (category D, n = 24). A single amplification product of minimum size and additional products of larger sizes corresponded to one and more bca repeats, respectively. Five of the 11 category B strains showed expression of low Mr c(alpha) in whole cell-based Western blotting. The results showed that a proportion of the GBS isolates harboured bca gene elements that either were not expressed or they expressed c(alpha) molecular variants which could not be detected by the whole cell-based FAT. This genotype/phenotype discrepancy should be considered in relation to GBS typing, including the selection of antibody reagents and the technical approach to c(alpha) protein detection.