Detection of Multidrug-Resistant Integrons Associated with Acinetobacter baumannii Isolated from Clinical and Environmental Samples

Abstract

The emergence of multidrug resistance (MDR) among pathogenic bacteria is a root cause of severe infections. It is threatening to observe that MDR is also found in ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens, which has caused a hike in nosocomial infection. The diminishing spectrum of treatment against these pathogens demands an alternative realm of treatment. One such nosocomial pathogen, Acinetobacter baumannii is known to cause pneumonia, blood stream infection, urinary tract infections, especially affecting immunocompromised individuals. Due to indiscriminate use of antibiotics, these pathogens have gained resistance to major classes of antibiotics through mutation and horizontal gene transfer via mobile genetic elements such as plasmids, transposons and integrons. This study mainly aims at identifying integron mediated drug resistance among clinical and environmental strains of A. baumannii. In this study, A. baumannii strains isolated from clinical and environmental samples were screened for antibiotic susceptibility tests. The multidrug resistant isolates were then checked for the presence of 3 classes of integrons viz Intl1 (Class 1), Intl2 (class 2) and, Intl3 (class 3). The integron region of the positive isolates was sequenced, and the drug-resistance gene cassettes were identified. All the clinical and environmental isolates were multidrug resistant. Three clinical isolates of A. baumannii showed positive amplification to Intl1 at 2kb, while none of the environmental isolates carried integrons, though they were multidrug resistant. The sequencing of the integron region of clinical isolates revealed the presence of three antibiotic resistance genes within the integron that encode resistance to chloramphenicol, rifampin, and aminoglycoside. This study prominently highlights the presence of class 1 integrons carrying different antimicrobial resistance determinants among A. baumannii isolated from clinical samples.