A cluster of infections caused by Enterobacter cloacae was observed among preterm neonates in a neonatal intensive care unit (NICU) of a pediatric hospital in Osnabruck, Germany. The presence of similar antimicrobial susceptibility patterns among the bacterial isolates prompted an investigation to determine whether a limited spread of a single strain existed. All 12 E. cloacae isolates from the NICU and 50 nonrelated strains were fingerprinted by small-fragment restriction endonuclease analysis (SF-REA) of EcoRI DNA digests. Selected isolates were further characterized by pulsed-field gel electrophoresis (PFGE) of NotIor XMaI-generated genomic restriction fragments. Epidemiologically unrelated strains were clearly discriminated by both methods. Results achieved by SF-REA and PFGE revealed that of the 12 isolates from the NICU, 11 belonged to the same genotypic cluster. Since all reagents and equipment for both techniques are commercially available, DNA fingerprinting by SF-REA or PFGE is proposed as a useful tool in the microbiology laboratory for investigating the epidemiological relatedness of E. cloacae strains of clinical and environmental origin. * Corresponding author. gel electrophoresis (PFGE) as typing tools for E. cloacae. The results are compared with those achieved by traditional methods available in a routine microbiology laboratory and are evaluated with respect to typeability, reproducibility, discriminatory power, and ease of use.

No abstract

Epidemiological fingerprinting of Klebsiella pneumoniae was performed by restriction endonuclease analysis (REA) of whole cell DNA. 11 isolates from 4 patients in an intensive care unit and 80 unrelated strains were examined in this study. DNA was cleaved with restriction endonuclease EcoR I, electrophoresed on 10% polyacrylamide gels, and restriction fragment patterns were visualized by silver staining. The analysis of small fragments within the cleavage patterns (SF-REA) yielded sufficient information for reliable strain identification. The gel patterns of unrelated strains exhibited marked differences by direct visual comparison. In contrast, the isolates from the ICU could only be subdivided into 2 types, supporting our suspicion of nosocomial infections in some of these patients. SF-REA was evaluated with regard to interstrain discriminatory ability, reproducibility, and practicability. Our results indicate that SF-REA may be used as a rapid, precise and reliable technique in typing K. pneumoniae strains.

No abstract

Whole cell DNA of Legionella pneumophila isolates was examined by small-fragment restriction endonuclease analysis (SF-REA). Fourteen serogroup 1 isolates from tap water in one hospital collected before and after eradication measures had been taken were compared with control strains of serogroup 1 and other serogroups that were not epidemiologically linked. DNA was digested with EcoRI and electrophoresed on polyacrylamide gels. The gel patterns were made visible by silver staining and analysed by direct visual comparison. All 15 epidemiologically unrelated strains of Legionella pneumophila serogroup 1 and of other serogroups exhibited different restriction fragment patterns. The isolates from the hospital could be clearly subdivided into two groups by SF-REA, suggesting that the hot water supply of the hospital was contaminated with two different strains. SF-REA performed on Legionella pneumophila serogroup 1 DNA enabled further subtyping of these organisms and thus appears to be a useful technique for investigating their epidemiology.