Transcriptional Response of Multidrug-Resistant Clinical Isolates to Ciprofloxacin Stress.

Background: The term "persisters" refers to a small bacterial population that persists during treatment with high antibiotic concentration or dose in the absence of genetic resistance. The present study was designed to investigate the transcriptional response in indigenous under the ciprofloxacin stress.

Methods: Isolation and identification of were carried out through standard microbiological protocols. The characterization of quinolone resistance was performed by estimating the quinolone susceptibility testing, MIC estimation, and detecting the QRDR and PMQR. Transcriptional response of the isolates to ciprofloxacin was determined using qPCR.

Results: Among 34 isolates, 23 (67%) were resistant to ciprofloxacin. Both QRDR ( and ) and PMQR ( and ) were detected in the isolates, and all were found resistant to ciprofloxacin. The mRNA levels of both and under the influence of ciprofloxacin were significantly increased. On ciprofloxacin exposure, the mRNA levels of the DNA damage response element () were raised in a time-dependent fashion. showed high-level resistance to ciprofloxacin in the presence of mutations in QRDR and PMQR genes.

Conclusion: The transcriptional response revealed the upregulation of DNA repair and protein folding elements ( and ) in ciprofloxacin stress and delayed cell division. The ciprofloxacin was found to trigger various stress responses in a time- and concentration-dependent manner.