Molecular Epidemiology of Infections Due to Enterobacter aerogenes: Identification of Hospital Outbreak-Associated Strains by Molecular Techniques

Abstract

Molecular techniques were used to study the epidemiology of infections due to Enterobacter aerogenes in a tertiary-care hospital. Sixty-two clinical isolates were collected from 43 patients over 3 months. Restriction endonuclease analysis (REA) of chromosomal DNA and repetitive-element polymerase chain reaction (rep-PCR) with primers based on repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) bacterial DNA sequences were used for genomic fingerprinting. REA with HindIII or EcoRI yielded complex banding patterns that differentiated community-acquired from some hospital-acquired organisms. Less complex fingerprints were obtained with rep-PCR, which also distinguished between epidemiologically unrelated strains. More discriminatory DNA fingerprints were provided by rep-PCR when REP primers rather than ERIC primers were used. Two clusters of genomically distinct isolates from patients with recent or current exposure to the hospital environment were identified by REA and rep-PCR. Most isolates within each cluster contained characteristic plasmids, and some isolates contained additional plasmids. These results suggest colonization and infection with genotypically related strains of E. aerogenes in a nosocomial setting. Although REA and plasmid profiling are useful techniques for the epidemiological typing of E. aerogenes, genomic fingerprinting with rep-PCR may offer the advantages of ease, speed, and broad species applicability over existing molecular-typing techniques.

Coexistence of SHV-4- and TEM-24-Producing Enterobacter aerogenes Strains before a Large Outbreak of TEM-24-Producing Strains in a French Hospital

“…Since that time, several outbreaks have been reported. The overview of epidemiological studies suggests two opposite situations in the world: the epidemic situation that occurred in the United States (21,31,35) and Belgium (15,24), characterized by sporadic outbreaks without any linkage and the French situation, characterized by the clonal dissemination of an ESBL-EA strain in nearly all of the hospitals in the country (8). A chronological review of the investigations conducted in France will give better insight into the purpose of this study.…”

“…They were investigated by using molecular typing methods such as pulsed-field gel electrophoresis (PFGE) (2,15,24,32), random amplified polymorphic DNA analysis (4,8,12,13,23), enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) (8,13,15,21), and ribotyping (4,21,23). In some studies, the ␤-lactam resistance was characterized, giving ESBL identification (4,8,11,14,32,35).…”

“…In some studies, the ␤-lactam resistance was characterized, giving ESBL identification (4,8,11,14,32,35). The outbreaks occurred in the United States (21,31,35), Belgium (15,24), and Austria (2). In France, ESBL-producing E. aerogenes (ESBL-EA) has become a threat since an epidemic clone producing TEM-24 ESBL has spread to nearly all French teaching hospitals, including the hospital of Amiens (8).…”

Rapid differentiation of phenotypically and genotypically similar Synechococcus elongatus strains by PCR fingerprinting.

“…REP-PCR with degenerate primers based on the REP element, has previously been shown to be sensitive in detecting minor differences among strains of the same bacterial genus and species (Versalovic et al 1991;De Bruijn 1992;Georghiou et al 1995). The technique is easy to perform and can be applied to large or small numbers of isolates.…”

“…The technique is easy to perform and can be applied to large or small numbers of isolates. REP-PCR shows broader species applicability and better discriminatory power than either plasmid profiling or genomic fingerprinting (Georghiou et al 1995). REP-PCR has considerably better discriminatory power than restriction analysis of the 16S rRNA gene or the 16S-23S spacer region (Appuhamy et al 1997).…”