Dissemination of multidrug-resistant, class 1 integron-carrying Acinetobacter baumannii isolates in Taiwan

Abstract

In this study, 283 multidrug-resistant Acinetobacter baumannii (MDR-AB) bloodstream isolates were collected between 1996 and 2004, from three teaching hospitals located in different regions of Taiwan. Susceptibility data showed that strains carrying class 1 integrons were significantly more resistant (p <0.01) to all tested antibiotics (except aztreonam and chloramphenicol) than strains lacking integrons, Seven types of gene cassette were identified among these strains, including two that have not been previously reported. The vast majority of the cassettes encoded aminoglycoside resistance genes, including aacA4, aacC1, aac(6')-II, aadA1, aadA2, aadA4 and aadDA1. Sixteen distinct ribotypes were identified in MDR-AB isolates carrying class 1 integrons. Only one strain was found to produce an extended-spectrum beta-lactamase, i.e. VEB-3. In the 18 imipenem-resistant strains, two carbapenenmase genes, bla(VIM-11) and bla(OXA-58), were found concomitantly in one isolate. An island-wide epidemic clone and an endemic clone from a hospital located in the northern region were identified by ribotyping. On the basis of the susceptibility data among the different ribogroups, the epidemic clone was associated more significantly with resistance to cefepime and ampicillin-sulbactam than was the endemic clone. In conclusion, the presence of class 1 integrons was significantly associated with resistance in MDR-AB, and the epidemic, class 1 integron-carrying MDR-AB clone was found to be widespread in Taiwan.

Significant spread of extensively drug-resistant Acinetobacter baumannii genotypes of clonal complex 92 among intensive care unit patients in a university hospital in southern Iran

“…The high degree of mobility that characterizes the class 1 integrons is illustrated by our finding that indistinguishable PFGE types varied in their integron content. In short, we found a high prevalence of class I integrons and low prevalence of class 2 integrons in XDR phenotypes, which agrees with data obtained in other investigations [6,28,35].…”

“…Genes mediating antimicrobial resistance are often incorporated into mobile genetic elements and integrons to promote acquisition of resistance genes and dissemination to other bacteria [6][7][8]. With regard to A. baumannii, CRAB isolates are frequently associated with the presence of OXA-23, OXA-24 and OXA-58 type class D carbapenemases [9].…”

Acinetobacter baumannii: biology and drug resistance — role of carbapenemases

“…An example of imipenem-resistant A. baumannii strain carrying bla IMP-5 gene within class 1 integron was reported by Da Silva and co-workers [81]. Also the studies of Huang and co-authors revealed the presence of multidrug-resistant A. baumannii isolates carrying within the class 1 integron the bla VIM-11 gene [82]. Additionally, the occurrence of bla SIM-1 was detected in class 1 integrons among seven clinical isolates of A. baumannii from Korea [83].…”

Class 1 integrons in non-clonal multidrug-resistant Acinetobacter baumannii from Iran, description of the new bla IMP-55 allele in In1243

“…Recent data indicate the role of class 1 integrons in the spread of MDR-AB in different hospitals in Europe and other parts of the world. Class 1 integrons carry different gene cassettes and are predominant among bacteria in the hospitals (Huang et al, 2008;. Epidemic strains of A. baumannii have been found to contain significantly more integrons than non-epidemic strains (Koeleman et al, 2001).…”