Detection of integrons in worldwide nosocomial isolates of Acinetobacter spp.

Abstract

OBJECTIVE: To examine the distribution of integrons in genotypically unrelated worldwide multiresistant clinical isolates of Acinetobacter spp. METHODS: The presence and genetic location of class 1, 2 and 3 integrons were examined in a genotypically heterogeneous collection of 25 nosocomial isolates of Acinetobacter spp., from 15 locations in 11 different countries worldwide, by hybridization and PCR-based methods. Class 1 integron structures were characterized genetically by a PCR mapping technique. RESULTS: Class 1 integrons were detected in 17 of the 25 Acinetobacter isolates examined. Only one isolate contained a class 2 integron. No class 3 integrons were detected. The integrons varied in size and in the number of inserted cassettes, but similar integrons were found in genotypically distinct isolates from different locations worldwide. These structures were integrated into the chromosome in all isolates where they were detected, although some integrons were capable of subsequent transfer or mobilization. Genes coding for aminoglycoside-modifying enzymes formed the predominant cassettes identified within the integrons. CONCLUSIONS: Clinical isolates of Acinetobacter spp. from diverse locations seem to share resistance mechanisms acquired from other genera by a variety of mechanisms, including dissemination of integrons. Once integrons are incorporated into the bacterial genome, Acinetobacter spp. are potentially able to act as a reservoir of resistance genes for other species and genera.

Identification of Epidemic Strains of Acinetobacter baumannii by Integrase Gene PCR

“…Only one clinical isolate, strain 3O, was found to contain a class 2 integron structure. Other investigators have also found predominantly class 1 integrons in Acinetobacter species (23). A survey by Gonzalez et al, however, demonstrated predominantly class 2 integrons in A. baumannii isolates from Chilean hospitals (7).…”

“…In class 3 only one integron has been described (2,21). The majority of integrons belong to class 1 and have been found predominantly in clinical isolates of gram-negative bacteria, including Acinetobacter species (14,18,19,23; M. E. Jones, E. Peters, A. M. Weersink, A. Fluit, and J. Verhoef, Letter, Lancet 349:1742-1743, 1997). A. baumannii strains may vary considerably in their epidemiological potential, and those strains that have been known to spread widely and rapidly among hospitalized patients have been designated epidemic A. baumannii strains.…”

Integron content of Salmonella enterica serotype Typhimurium strains isolated in Hungary in the years 1997-1999

“…The instability of integrons especially in the absence of selective pressure was suggested by Recchia et al (1994) and Seward and Towner (1999). In contrast, high stability was found among integrons of bacteria isolated from the same patients at different times (Maguire et al, 2001) or from various European hospitals (Martinez-Freijo et al, 1999).…”

Safety Assessment of Transgenic Organisms, Volume 4

“…A hybrid class 2 integron composed of intI2 and the 3 conserved segment of class 1 integrons was reported in A. baumannii (Ploy et al, 2000). Class 3 integrons-encoded resistance were reported in A. baumanni (Seward, 1999;Shibata et al, 2003).…”

“…A hybrid class 2 integron composed of intI2 and the 3 conserved segment of class 1 integrons was reported in A. baumannii (Ploy et al, 2000). Class 3 integrons-encoded resistance were reported in A. baumanni (Seward, 1999;Shibata et al, 2003).Integrons can be found on plasmids or chromosomally integrated, where they are very stable.The important role played by integrons in antibiotic resistance and in the epidemic behavior of A. baumannii was emphasized in many studies. Koeleman et al (2001) report that integrons are present in 50% of the A. baumannii strains analyzed.…”