Analysis of Legionella pneumophila serogroup 6 strains isolated from a hospital warm water supply over a three-year period by using genomic long-range mapping techniques and monoclonal antibodies

Abstract

Over a period of 3 years, Legionella pneumophila serogroup 6 strains were isolated from warm water outlets and dental units in the Dental Faculty and from the Surgery and Internal Medicine Clinics at the University * Corresponding author. serogroup 6 strains isolated during a 3-year surveillance from a water system at the School of Medicine in Dresden, Germany. MATERIALS AND METHODS Water samples. After at least 16 h of stagnation, 0.3to 0.5-liter water samples were collected from dental units and warm water taps in the Faculty of Dentistry, School of Medicine in Dresden over a 3-year period. In the Internal Medicine Clinic, Surgery Clinic, and the bacteriological unit, warm water specimens from taps and faucets were sampled once in the same manner. The four facilities mentioned above are separate buildings, connected with a ring pipe warm water system. This water system is fed by two separate hot water tanks, which were employed one after the other. The temperature in these tanks was adjusted to between 56 and 58°C. During this study, no measures for eliminating legionellae such as superheating to 70°C or chlorination were made. The water temperature in the warm water system ranged from 30 to 50°C at the time of water collection. Legionella strains and culture conditions. Water samples were concentrated by centrifugation at 5,500 x g for 30 min. Legionellae were isolated on ACES [N-(2-acetamido)-2aminoethanesulfonic acid]-buffered charcoal-yeast extract (BCYE) agar medium (4, 8) supplemented with 0.1% ox-ketoglutarate (Sigma Corp.

A multicenter evaluation of genotypic methods for the epidemiologic typing of Legionella pneumophila serogroup 1: results of a pan-European study

“…Of the many molecular typing methods applied to L. pneumophila, PFGE is probably the most widely used and is generally considered to be highly discriminatory [16,18,19,43]. Again, the results of this study confirm this view.…”

“…Four of the methods employed the restriction endonuclease S$I, and two NutI. Except where indicated, the conditions used for the PFGE methods were based on those described by Luck et a1 [43,44], with the minor modifications detailed below. Following digestion of genomic DNA with $1 or NotI, electrophoresis was carried out using 1% agarose gels in 0.5 X TBE buffer (pH 8.3-8.5) using a CHEF DRII (Bio-Rad Laboratories, Hercules, CA, USA), CHEF DR-111 apparatus (Bio-Rad) or Gene Navigator (Pharmacia Biotech, Uppsala, Sweden) and the conditions described below.…”

Genomic heterogenicity amongst phenotypically similarLegionella micdadeistrains

“…In conclusion, serotyping was not very useful for subtyping of L. micdadei. These findings are in contrast to observations concerning strains of L. pneumophila, which could be divided into several serogroups and furthermore in mAb subtypes [2, 6,12]. Considering all phenotypic characteristics, the nine L. micdadei strains could not be differentiated clearly.…”

Legionella: from environmental habitats to disease pathology, detection and control

“…1). L. pneumophila serogroup 6 strains were isolated from warm water outlets and dental units at the University of Dresden in Germany (Luck et al, 1991). Dentists in Dresden were found to have a higher prevalence of antibodies against legionellae than the general public, suggesting greater exposure to Legionella in the dental of®ce (Luck et al, 1992).…”