Role of Integrons in Antimicrobial Susceptibility Patterns of Acinetobacter baumannii

The relationship between the presence and types of integrons and the antimicrobial susceptibility patterns of Acinetobacter baumannii was investigated A total of 134 non-duplicated A baumannii isolates, 54 5% (n = 73) of which were subsequently found to carry class 1 integrons, were collected from a regional hospital in Taiwan between March and September 2007 Only two types of gene cassette array, aacA4-catB8-aadAl and aacCl-orfP-orfP-orfQ-aadAl, were identified Susceptibility data showed that those strains carrying integrons were significantly more resistant to all antibiotics tested except ampicillin/sulbactam and imipenem An epidemiological study revealed that the same integron could be found in different unrelated strains These findings suggest that the presence of integrons in A baumannii is responsible for both the horizontal transfer of antibiotic-resistance genes related to aminoglycosides and chloramphenicol and also represents a marker of multidrug resistance and epidemic potential