Upstream region of OprD mutations in imipenem-resistant and imipenem-sensitive Pseudomonas isolates

Masoumeh Kiani,Hengameh Zandi,Mansoor Khaledi,Akram Astani,Mohadeseh Zarei,Hamed Afkhami,Soodabeh Rostami,Nahid Rezaei Khozani,Gilda Eslami

doi:10.1186/s13568-021-01243-3

Abstract

The current study was aimed at investigating the prevalence of the mutations upstream of the oprD coding region and its promoters among imipenem-resistant and sensitive Pseudomonas aeruginosa isolated from educational hospitals in Yazd City, Iran. All isolates were identified by the conventional biochemical tests. Then, the antibiotic resistance of these isolates was determined using the disk diffusion method according to the CLSI guidelines. Also, the E.test was performed to determine the minimum inhibitory concentrations (MIC) of imipenem. The mutations of this gene were recognized by the amplification of this region and subsequently sequenced. Sequencing of the genomic region upstream of oprD these regions were done in the 29 clinical strains. Statistical analysis was done by the statistical software SPSS-18. Seventy (77.7%) of isolates had MIC ≥ 16 and were resistant to imipenem. Mutations of the upstream of the oprD gene and its promoters were seen in 25 (86.2%) isolates and 4 isolates had no mutation. One isolate had a base substitution A→Cat nt 25 in the coding region and this isolate had a point mutation leading to an amino acid change at positions 9 (I→L). Our study results indicated that none of the strains had mutation in Shine-Dalgarno and the point mutations were the most common mutations upstream of the oprD coding region among P. aeruginosa isolates. Mutations were observed in imipenem-resistant isolates and it seems this mechanism is effective in resistance of isolates to imipenem and this confirmed that the indiscriminate use of antibiotic should be controlled.

Highlights

Pseudomonas aeruginosa is an opportunistic pathogen that causes a variety of infections in immunocompromised patients.‫ ‏‬In recent years, Antibiotic resistance of P. aeruginosa is increasing and the selection of suitable treatments has become difficult and is associated with increased morbidity and mortality (Riera et al 2011; Yan et al 2014).Carbapenems, mainly imipenem and meropenem, are important and useful antibiotics for the treatment of infections due to multidrug-resistant Pseudomonas
Bacterial isolates Of 90 P. aeruginosa isolates, 38.9%, 20%, and 13.3% of them were isolated from burn wounds, urine, and wound specimens respectively
One isolate had a base substitution A→ Cat n t 25 in the coding region, and this isolate had a point mutation leading to an amino acid change at positions 9(I→L)

Summary

Introduction

Pseudomonas aeruginosa is an opportunistic pathogen that causes a variety of infections in immunocompromised patients.‫ ‏‬In recent years, Antibiotic resistance of P. aeruginosa is increasing and the selection of suitable treatments has become difficult and is associated with increased morbidity and mortality (Riera et al 2011; Yan et al 2014).Carbapenems, mainly imipenem and meropenem, are important and useful antibiotics for the treatment of infections due to multidrug-resistant Pseudomonas. Carbapenem resistance of P. aeruginosa is mainly due to a combination of different factors, including low permeability of outer membrane porin and mutations in the gene encoding OprD, the production of the AmpC bate-lactamases, overproduction of efflux systems, and producing Carbapenemase (Hancock and Brinkman, 2002; Pirnay et al 2002; Rostami et al 2018). Among these mechanisms, the Loss or mutation of outer membrane porin (OprD) and promoter of this gene appears to be the most common mechanisms of intrinsic resistance to imipenem and a lesser extent to meropenem. This mechanism causes blocking of the entrance of carbapenems imipenem into a bacterium (Amin et al 2005; Shen et al.2015)

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