Juha Kauppinen

Hospital water supply as a source of disseminated Mycobacterium fortuitum infection in a leukemia patient.

Nosocomial acquisition of Mycobacterium fortuitum led to a disseminated infection in a leukemia patient. A linkage to showerhead water was supported by molecular typing of clinical and environmental isolates. Contamination of the hospital water system with microbes that are relatively resistant to common sanitation processes poses an increased risk of infection to neutropenic patients.

Persistent Legionella pneumophila colonization of a hospital water supply: efficacy of control methods and a molecular epidemiological analysis

After a nosocomial outbreak caused by Legionella pneumophila serogroup 5, the hospital water distribution system, which was found to be colonized by L. pneumophila serogroups 5 and 6, was decontaminated by the superheat and flush method and by installing an additional heat‐shock unit in one of the hot water circuits. This unit exposed the recirculated water to a temperature of 80 °C. The efficacy of the decontamination measures was evaluated by monitoring the temperatures and legionella concentrations at different parts of the hot water distribution system. The genetic diversity of the colonizing legionella flora was examined using two genotyping methods: amplified fragment length polymorphism analysis (AFLP) and random amplified polymorphic DNA (RAPD) analysis. Selected serogroup 6 strains were also analyzed by sequence‐based typing (SBT). The results indicated that long‐term eradication of serogroup 5 strains was never achieved. Only one serogroup 6 strain was never isolated after the superheat and flush. In all, according to genetic fingerprints, the diversity of Legionella strains in a hospital water system remains stable over the years regardless of the use of recommended disinfection procedures.

Nosocomial Legionella pneumophila serogroup 5 outbreak associated with persistent colonization of a hospital water system.

An outbreak of infections caused by Legionella pneumophila serogroup 5 was detected in a university hospital, and nosocomial reservoirs of the legionella epidemic were examined. Clinical isolates from two patients who had been affected by the L. pneumophila serogroup 5 outbreak, and from another patient with a legionella infection caused by the same serogroup 3 years later, were compared to L. pneumophila serogroup 5 isolates from the hospital water supply by two molecular methods, amplified fragment length polymorphism (AFLP) analysis and random amplified polymorphic DNA analysis (RAPD). Genotyping confirmed the epidemiological linkage of the first two patients, and linked their infections with the hospital water supply. The third clinical strain, which was also linked to the hospital water, was very similar to the epidemic strain. Even though the water distribution system was sanitized (superheat and flush sanitation), the epidemic strain was shown to be persisting in the hospital water outlets several years after its initial discovery.

Rapid and specific detection of three different G adhesin classes of P-fimbriae in uropathogenic Escherichia coli by polymerase chain reaction

Abstract Uropathogenicity of Escherichia coli has a strong association with P fimbriae. At the tip of P fimbriae are located G adhesins which mediate binding to glycolipid receptors. The G adhesins are encoded by pap or prs gene clusters. The three receptor binding variants of G adhesins (Classes I to III) recognized so far, differ in their binding to different isoreceptors of the Galα1–4gal-containing glycolipid family. Lately, the genetic detection of G adhesins by colony hybridization or polymerase chain reaction (PCR) has been used as an alternative to previous phenotypic P fimbria detection methods. In the present study, 257 E. coli urine isolates from clinically properly characterized patients with either acute cystitis or recurrent E. coli infections were examined for the three G adhesin classes with a PCR-based method. The PCR reaction was carried out with four oligonucleotide primers in a single reaction tube. Sixty-five isolates (25%) had genes for Class II G adhesin, 31 (12%) for Class III and two additional isolates had genes for both Class II and III G adhesins. Of the total of 98 strains possessing genes for P fimbriae, 26 (27%) were undetectable with the previous P-specific latex agglutination test and 7 (7%) strains with the mannose-resistant heme agglutination method. The new PCR method presented in this study allows an easy, fast, cheap, sensitive and reliable detection method for P fimbriae as well as the specific G adhesin type. Thus, it allows further evaluation of the clinical significance of these G adhesins in strains causing other types of urinary tract infections (UTI) other than cystitis.

RFLP analysis of Mycobacterium malmoense strains using ribosomal RNA gene probes: an addition tool to examine intraspecies variation

To examine the intraspecies variation of Mycobacterium malmoense, 29 clinical isolates, chemotyped by thin-layer chromatography of their surface glycolipids into five subgroups, were typed using RFLP analysis. Two 32P-labelled ribosomal RNA (rRNA) gene fragments were used as probes for chromosomal DNA digested with BanI. By comparison of the fingerprint patterns, the strains could be divided into five ribotypes, two major and three minor ones. The chemotypes were not connected to any of the ribotypes. Combination of the results of the two techniques produced a considerable resolution. This method is a useful additional tool when studying the epidemiological behaviour of M. malmoense.

PCR-based typing of Mycobacterium avium isolates in an epidemic among farmed lesser white-fronted geese (Anser erythropus)

Mycobacterium avium is an important veterinary pathogen causing avian tuberculosis in birds. The aim of the study was to evaluate the genetic relatedness in M. avium isolates from deep tissues of farmed lesser white-fronted geese with avian tuberculosis and in samples from the farm environment. The strains were analyzed by two PCR-based typing methods, inverted repeat (IR) typing and random amplified polymorphic DNA (RAPD) analysis. The primers for the inverted repeats of the insertion sequences IS1245 and IS1311 were used in IR typing, and the RAPD analysis was performed with six primers. Seven of the nine avian strains yielded an identical pattern in the IR typing, but they could be divided into two groups in the RAPD analysis. The remaining two bird isolates had an identical IR pattern (IR cluster II) which they shared with two environmental isolates. However, the RAPD analysis revealed that these environmental isolates had a RAPD pattern (RAPD cluster VI) distinct and different from either of the bird isolates (RAPD clusters II and IV). In all, four M. avium strains were verified as being inducers of avian tuberculosis in birds, and all were distinct from the three environmental strains identified. Thus, the results did not confirm the preliminary idea that a single strain had caused the epidemic. The polymorphism among M. avium strains highlighted the great biodiversity among an M. avium population even in a limited environmental setting during a short time span, and indicated the high susceptibility to avian tuberculosis of lesser white-fronted geese.

Random amplified polymorphic DNA (RAPD) analysis of Escherichia coli strains : comparison of urinary and concomitant blood isolates of urosepsis patients

The discriminatory power of random amplified polymorphic DNA (RAPD) analysis was assessed for detection of intraspecies variation in Escherichia coli strains of clinical origin. Three primers (OPF 5, OPF 7 and OPF 8) were preselected from commercial 10‐mer primers by the number of distinct bands obtained. These primers were used in testing 26 urinary and 13 blood isolates from 26 patients and E. coli ATCC 25922, OPF 5, OPF 7 or OPF 8 alone separated the strains into 15 to 21 RAPD types. A combination of the results of the three primers gave 25 RAPD types. When blood and urine isolates of each patient were analysed in parallel, all blood‐urine pairs were found identical, and with one exception they were also unique. RAPD analysis had a high discriminatory power. It separated the strains equally well or better than ribotyping, and obviously better than serotyping which grouped the urine strains into 8 serogropus leaving 18 strains untypable or incompletely typed. Thus, to verify the identity or non‐identity of isolated E. coli strains, RAPD analysis was shown to be a sensitive and reproducible technique which is technically less demanding, more rapid and more economical than either serotyping or ribotyping. However, in its present application, this technique cannot fully replace determination of the serotype or virulence factors which may show correlations with different manifestations of infection.