- Volume 46, Issue 11, 1997

The incidence of Chlamydia pneumoniae infection was determined in patients with chronic obstructive pulmonary diseases (COPD) by prospective serial serology. Chlamydia-specific IgG, IgM and IgA antibodies were detected with a recombinant DNA lipopolysaccharide (LPS) ELISA as well as with a micro-immunofluorescence (MIF) assay with C. pneumoniae elementary bodies. From 271 consecutive COPD patients who visited the outpatient clinic of the department of pulmonary diseases (211 males, 60 females, age range 34-88 years, mean age 66 SD 10 years), blood samples (n = 1058) were taken every 2-7 months; the observation period ranged from 3 to 19 months (mean 15 SD 4). The prevalence of chlamydial IgG was 72% with the MIF and 53% with the rDNA LPS ELISA. More than 90% of the COPD patients had no significant changes in their chlamydia-specific IgG, IgA and IgM titres in either test during the observation period. Seven (3%) patients had MIF results indicating acute C. pneumoniae infection during their surveillance period, of whom five were confirmed by rDNA LPS ELISA. Eleven (4%) additional patients were infected during observation, as determined by rDNA LPS ELISA only. These patients had significantly elevated C. pneumoniae-specific IgG and IgA MIF titres, as compared with the patients without infection. All 18 patients with serological evidence of acute infection during their surveillance period were re-tested in a commercial MIF test that can distinguish between C. pneumoniae, C. trachomatis and C. psittaci LPS-specific antibodies, but no evidence of C. trachomatis or C. psittaci infection was found. The incidence of chlamydial infection was 2.2 and 5.3/100 person-years, when diagnosed by MIF and rDNA LPS ELISA, respectively. It is concluded that the rDNA LPS chlamydia assay may currently be the most sensitive serological tool for diagnosing recent respiratory chlamydia infections and that C. pneumoniae infection occurs frequently in COPD patients.

The aim of the present study was to investigate the biological role of cardiolipin antibodies during Treponema pallidum infection. Inhibition of the binding of treponemal specific antibodies at the early and late stages of infection by cardiolipin antibodies was shown in the fluorescence treponemal antibody absorption (FTA-ABS) test and T. pallidurn immobilisation (TPI) test. Incubation of treponemes with cardiolipin antibodies followed by a second incubation with treponemal specific antibodies resulted in a reduction of the titres of the FTA-ABS test and the TPI test. The findings suggest that cardiolipin antibody production should be considered as a virulence mechanism of pathogenic treponemes with the purpose of evading the host defence mechanisms.

An outbreak of multiresistant Klebsiella pneumoniae has continued in the Grampian Region of Scotland since 1992. The organism, which generally produces an extended-spectrum β-lactamase (ESBL), has spread to several hospitals and nursing homes. DNA from 80 possible outbreak isolates was digested with the restriction endonucleases XbaI and SpeI, and the patterns obtained by pulsed-field gel electrophoresis were compared. Restriction patterns of 79 of the isolates were found to be highly similar with both restriction enzymes, whereas one isolate was unrelated. The outbreak isolates were divided into six subtypes with SpeI and 16 subtypes with XbaI. These subtypes were independent of antibiotic susceptibility pattern, date of isolation and ward of origin, but the XbaI subtype did correlate with the SpeI subtype. It was concluded that the Klebsiella isolates of this outbreak were clonally related.

A rapid, simplified procedure combining random amplified polymorphic DNA (RAPD) fingerprinting of boiled cultures with high resolution agarose gel electrophoresis was used to compare strains from 46 pathogenic leptospiral serovars. The serovars were placed in eight groups on the basis of RAPD profile similarities. Groups 1–7 corresponded with the genome species Leptospira interrogans, L. borgpetersenii, L. santarosai, L. noguchii, L. weilii, L. kirschneri and L. meyeri. The eighth group did not correspond with a known genome species and may represent a new genome species. Primer choice determined the degree of discrimination possible between closely related serovars and genotypes. This procedure, unlike other procedures used for analysing taxonomic relationships between leptospiral serovars, does not require extensive DNA purification, polyacrylamide gel electrophoresis or autoradiography.927

IS1245-based restriction fragment length polymorphism (RFLP) analysis has been proposed recently for molecular typing of Mycobacterium avium isolates. As there is no standardised method with respect to the optimal restriction enzyme, three restriction endonucleases were tested for analysis of 17 human isolates. The restriction endonucleases, selected on the basis of the physical maps of IS1245 and of the highly homologous IS1311, were BsaAI, that cleaves IS1245, PvuII, that cleaves IS1311, and NruI, that cleaves both IS1245 and IS1311. All the restriction endonucleases yielded polymorphic and complex RFLP patterns. However, BsaAI- and NruI-generated bands were more evenly distributed and easier to detect than PvuII-generated bands, most of which clustered in a narrow zone of the fingerprint. In some cases, DNA digestion with BsaAI or NruI yielded probe-specific restriction fragments of molecular size lower than expected. Moreover, digestion with NruI, which was expected to generate the highest numbers of bands in all the isolates, yielded fewer bands than were obtained with BsaAI or PvuII in 14 and 5 isolates, respectively. These findings might suggest the existence of unidentified IS1245-related insertion element(s) in M. avium isolates. Computer analysis of the IS1245-based RFLP patterns of M. avium isolates showed that the restriction endonucleases were capable, although with minor differences, of defining distinct banding patterns and clusters of identical or highly related isolates, thus confirming IS1245-based RFLP analysis as a useful technique for epidemiological studies.

The rRNA gene restriction patterns and the polymerase chain reaction (PCR) fingerprinting types of 53 Vibrio choferue O1 isolates were studied. Five and eight patterns were observed from 27 toxigenic and 26 non-toxigenic O1 isolates after BgfI cleavage. PCR fingerprinting with three primer sets aimed at enterobacterial repetitive intergenic consensus (ERIC) sequences, ERIC-related sequences in V. cholerae, another kind of repeated sequences in V. cholerae (VCR) and arbitrary sequences divided the same strains into seven and 10 PCR types, respectively. Eight ribotypes had unique PCR patterns. PCR fingerprinting identified more than one pattern among isolates within each of the remaining ribotypes. However, ribotyping was able to differentiate the same PCR types in one case. A single ribotype and a single PCR pattern were found in toxigenic O1 strains isolated in Taiwan from imported food and imported cases of cholera between 1993 and 1995. Typing of V. cholerae O1 by PCR fingerprinting correlated well with ribotyping, but was more discriminating. PCR assay provides a rapid and simple means of typing these strains for epidemiological studies.

Thirteen restriction endonuclease-containing strains were isolated from a collection of 186 clinical isolates of Shigella spp. Among these, eight and five isolates carried isoschizomers of EcoRII and NciI, respectively. The former restriction-modification (R-M) system was homologous to that of EcoRII and was located on plasmids with sizes of 46.6 or 55.6 kb. Isolates producing NciI isoschizomers contained a 5.7-kb non-transferable plasmid. Together with antimicrobial susceptibility tests and plasmid profile studies, it is concluded that these two R-M systems are not widely spread but confined to strains with similar antibiotic resistance and plasmid profile.