Detection of Toxin-Antitoxin System in Acinetobacter baumannii Isolated from Patients at Zagazig University Hospitals

Abstract

Increased resistance to antibiotics among Acinetobacter baumannii (A. baumannii) isolates is a rising problem, and new alternatives should be provided to overcome this problem. Toxin-Antitoxin system (TA) is considered a promising essential target for antimicrobial drugs. Objective: To detect the prevalence of toxin-antitoxin system in A. baumannii isolated from patients at Zagazig University Hospitals. Methodology: Following isolation, oxidase test and API20NE were used to identify A. baumannii, antibiotic susceptibility testing was performed to all isolates obtained, and amplification and screening of functional mazEF, relBE and higBA toxin-antitoxin genes were done by PCR and RT-PCR, respectively. Results: Out of 252 clinical specimens collected, 27(10.7%) were A. baumannii; 13 (15.3%) isolates were isolated from endotracheal aspirates, 4 (13.3%) from sputum samples, 7 (9.2%) from urine, 2 (4.5%) from pus, and 1 (14.3%) from blood. Most of the isolates were multidrug resistant, and the highest susceptibility was to meropenem (66.7 %) followed by imipenem (63%). Regarding PCR results, 22 isolates (81.5%) had relBE gene, 17 (62.9%)had mazEF gene, and 8(29.6%) had higBA gene. In the RT-PCR results, all genes were functional in all isolates. Conclusion: TA system genes are prevalent among A. baumannii isolates, in particular; relBE and mazEF genes and they are functional.

Evaluating the antibacterial effect of meropenem-loaded chitosan/sodium tripolyphosphate (TPP) nanoparticles on Acinetobacter baumannii isolated from hospitalized patients

“…According to our results, the highest rate of A. baumannii isolates was collected from the trachea specimens (31 isolates; 51.7%), which is consistent with the findings reported in a study by Alkasaby and colleagues [42]. Furthermore, as reported by Maghraby et al, the majority of A. baumannii isolates were related to chest infection specimens [26]. However, Al Mobarak et al reported some contradicting results in this regard as they reported that A. baumannii isolates were mainly isolated from wounds, respiratory secretions, urine, and blood [43].…”

“…To our knowledge, only a few studies have investigated the prevalence and functionality of the TA system genes in bacterial isolates. According to a similar study on 27 A. baumannii isolates, 62.9% had the mazEF gene, 81.5% had the relBE gene, and 29.6% had the higBA gene [ 26 ]. As reported by Ghafourian et al, the chromosomal DNA of all of the A. baumannii isolates (100%) were positive for mazEF , and that relBE was found in the chromosomal DNA of only 88.2% of the bacterial isolates whereas higBA was the least prevalent gene (4.7%) in the bacterial isolates [ 7 ].…”

“…The extracted DNA was used as the template for conventional PCR assay for determining the presence of mazEF , relBE , and higBA genes. The primers used for the PCR assay were previously designed by Maghraby et al (Table 1 ) [ 26 ]. For each round of PCR, 3 µg of the template DNA, 2.5 µL of 10X PCR buffer, 0.5 µL of 10 mM dNTPs, 0.75 µL of 50 mM MgCl 2 , 0.25 µL of 5 U/µL of Taq DNA polymerase, and 25 pmol of each primer (forward and reverse) were mixed and brought to a final volume of 25 µL using sterile DNase/RNase-free double-distilled water (DDW).…”