Distribution and molecular profiling of class 1 integrons in MDR Acinetobacter baumannii isolates and whole genome-based analysis of antibiotic resistance mechanisms in a representative strain

Abstract

The class 1 integron is an important driver of the nosocomial dissemination of multidrug-resistant (MDR) bacteria, such as Acinetobacters. In this study, we characterized the gene cassette arrays of class 1 integrons in Acinetobacter baumannii, where the detailed structure of these integrons for 38 clinical strains was analyzed. The results showed that there are three types of gene cassette arrays that are carried by different class 1 integrons, among them the aac(6')-IId-catB8-aadA1 array was the most prevalent. For detailed analysis of the integron structure, whole genome sequencing was carried out on strain AB16, and it was found that a single integron on its chromosome has a partial Tn21 transposon in its 5' flanking region and two complete copies of the insertion element IS26 in both the 5' and 3' flanking regions, indicating that the integron could be acquired by horizontal gene transfer. Furthermore, there is one resistance island AbaR22, one bla gene containing a transposon, four intrinsic resistant genes and one efflux pump that together confer six types of antibiotic resistance.

Incidence and Characterization of Salmonella Isolates From Raw Meat Products Sold at Small Markets in Hubei Province, China

“…Our results indicated that 30.3% of isolates were resistant to 4–6 antimicrobial agents and 4.5% were resistant to 7–9 antimicrobials. This indicated that antimicrobial resistance among Salmonella isolates from retail meat in Hubei Province was lower than that in other areas of China (Zhu et al, 2014; Wang et al, 2017). In our study, the highest rates of antimicrobial resistance were to the sulfonamides, tetracycline, amoxicillin, ampicillin and chloramphenicol.…”

<p>Comparative genomic analysis and multi-drug resistance differences of <em>Acinetobacter baumannii</em> in Chongqing, China</p>

“…In addition, the sulfonamide resistance genes sul1 and sul2 were present in 5 strains and 2 strains, respectively,28 the quinolone resistance genes AAC(6ʹ)-Ib9 and AAC(6ʹ)-Ib’ were found in only 2 strains,29 and the chloramphenicol resistance gene catB8 was present in 4 strains 30. With the exception of MDR-CQF, the other 9 strains each contained the tetracycline resistance-related gene tet (B),31 the macrolide resistance-related gene msrE,32 and the aminoglycoside resistance-related gene armA 33…”

Dissemination of Classes 1, 2, and 3 Integrons in Acinetobacter baumannii Strains Recovered from Intensive Care Units Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism

“…In a study conducted by Nasr et al (14), a high rate of resistance to amikacin (90%) and gentamicin (85%) was reported. Zhu et al (15) reported that among 39 A. baumannii isolates tested, 33 (84.6%) were resistant to gentamycin and 32 (82.1%) were resistant to amikacin. In another study form Taiwan, the rates of resistance to gentamycin and amikacin were 57.5% and 56.7%, respectively (16).…”