Detection of ISPa1328 and ISPpu21, Two Novel Insertion Sequences in the OprD Porin and blaIMP-1 Gene Among Metallo-Beta-Lactamase-Producing Pseudomonas aeruginosa Isolated From Burn Patients

Document Type : Original Article


1 Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran

2 Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, IR Iran



Carbapenemes are a good choice for treatment of infections caused by multidrug resistant Pseudomonads aeruginosa. The emergence of carbapenem resistance has become a major problem in treatment of this organism especially among immunocompromised patients including burn patients.

The aim of this study was to investigate carbapenem-resistance mechanisms among burn patients in Tehran, Iran, during 2014 - 2015.

The antibiotic resistance phenotypic test was accomplished by the Kirby Bauer disk diffusion method. The phenotypic investigation of metallo-beta-lactamase (MBL) producers was evaluated by the combined disk diffusion test (CDDT) method. The prevalence of MBL genes, including blaIMP-1 and blaVIM-1 was evaluated by polymerase chain reaction (PCR) and sequencing methods. Amplification of oprD was performed by PCR and the results of sequencing were aligned with wild-type P. aeruginosa strain PAO1.

A total of 100 P. aeruginosa were investigated, of which, 95 were resistance to imipenem. Out Of 95 imipenem resistant isolates,, 81 (85.2%) were MBL producers. Among all isolates, 13 strains carried the blaIMP-1 gene, whereas all of the strains were negative for the blaVIM-1 gene. Amplification of OprD porin was performed for all 100 P. aeruginosa strains. Two insertion sequences (ISs) including ISPpu21 and ISPa1328 were detected in PCR products of OprD gene, that were larger than expected.

The prevalence of β-lactamase-producing isolates and their isolation from life-threatening infections in burn patients is increasing at an alarming rate worldwide. Also, we have identified two novel IS elements, ISPa1328 and ISPpu21, in P. aeruginosa isolates from hospitals in Tehran, Iran. In most of the isolates, insertional inactivation of oprD by ISPa1328 and ISPpu21 were associated with carbapenem resistance.


11. Rossolini GM, Mantengoli E. Treatment and control of severe infections
caused by multiresistant Pseudomonas aeruginosa. Clin Microbiol
Infect. 2005;11 Suppl 4:17–32. doi: 10.1111/j.1469-0691.2005.01161.x.
[PubMed: 15953020].
12. Walsh TR, Toleman MA, Poirel L, Nordmann P. Metallo-betalactamases:
the quiet before the storm?. Clin Microbiol Rev.
2005;18(2):306–25. doi: 10.1128/CMR.18.2.306-325.2005. [PubMed:
13. Shahcheraghi F, Nikbin VS, Feizabadi MM. Identification and
genetic characterization of metallo-beta-lactamase-producing
strains of Pseudomonas aeruginosa in Tehran, Iran. New Microbiol.
2010;33(3):243–8. [PubMed: 20954442].
14. Saffari M, Firoozeh F, Pourbabaee M, Zibaei M. Evaluation of metallo-
-lactamase-production and carriage of bla-vim genes in pseudomonas
aeruginosa isolated from burn wound infections in Isfahan.
Arch Trauma Res. 2016;Inpress.
15. Radan M, Moniri R, Khorshidi A, Gilasi H, Norouzi Z, Beigi F. Emerging
Carbapenem-Resistant Pseudomonas aeruginosa Isolates Carrying
bla IMP Among Burn Patients in Isfahan, Iran. Arch Trauma Res.
16. Hakemi Vala M, Hallajzadeh M, Hashemi A, Goudarzi H, Tarhani M,
Sattarzadeh Tabrizi M, et al. Detection of Ambler class A, B and D sslactamases
among Pseudomonas aeruginosa and Acinetobacter baumannii
clinical isolates from burn patients. Ann Burns Fire Disasters.
2014;27(1):8–13. [PubMed: 25249841].
17. Saderi H, Lotfalipour H, Owlia P, Salimi H. Detection of metallo- -
lactamase producing pseudomonas aeruginosa isolated from burn
patients in Tehran, Iran. Labmedicine. 2010;41:609–12.
18. Ghamgosha M, Shahrekizahedani S, Kafilzadeh F, Bameri Z, Taheri
RA, Farnoosh G. Metallo-beta-Lactamase VIM-1, SPM-1, and IMP-1
Genes Among Clinical Pseudomonas aeruginosa Species Isolated
in Zahedan, Iran. Jundishapur J Microbiol. 2015;8(4):17489. doi:
10.5812/jjm.8(4)2015.17489. [PubMed: 26034547].
19. Rojo-Bezares B, Estepa V, Cebollada R, de Toro M, Somalo S, Seral C,
et al. Carbapenem-resistant Pseudomonas aeruginosa strains from a
Spanish hospital: characterization of metallo-beta-lactamases, porin
OprD and integrons. Int J Med Microbiol. 2014;304(3-4):405–14. doi:
10.1016/j.ijmm.2014.01.001. [PubMed: 24594145].
20. Al-Bayssari C, Valentini C, Gomez C, Reynaud-Gaubert M, Rolain
JM. First detection of insertion sequence element ISPa1328 in
the oprD porin gene of an imipenem-resistant Pseudomonas
aeruginosa isolate from an idiopathic pulmonary fibrosis patient
in Marseille, France. New Microbes New Infect. 2015;7:26–7. doi:
10.1016/j.nmni.2015.05.004. [PubMed: 26137309].
21. Diene SM, L’Homme T, Bellulo S, Stremler N, Dubus JC, Mely L,
et al. ISPa46, a novel insertion sequence in the oprD porin gene
of an imipenem-resistant Pseudomonas aeruginosa isolate from a
cystic fibrosis patient in Marseille, France. Int J Antimicrob Agents.
2013;42(3):268–71. doi: 10.1016/j.ijantimicag.2013.06.001. [PubMed:
22. Wolter DJ, Acquazzino D, Goering RV, Sammut P, Khalaf N, Hanson
ND. Emergence of carbapenem resistance in Pseudomonas
aeruginosa isolates from a patient with cystic fibrosis in the absence
of carbapenem therapy. Clin Infect Dis. 2008;46(12):137–41. doi:
10.1086/588484. [PubMed: 18462098].