Tunisian Multicenter Study on the Prevalence of Colistin Resistance in Clinical Isolates of Gram Negative Bacilli: Emergence of Escherichia coli Harbouring the mcr-1 Gene

Sana Ferjani; Elaa Maamar; Asma Ferjani; Khaoula Meftah; Hager Battikh; Besma Mnif; Manel Hamdoun; Yosra Chebbi; Lamia Kanzari; Wafa Achour; Olfa Bahri; Adenene Hammami; Meriam Zribi; Hanen Smaoui; Ilhem Boutiba-Ben Boubaker

doi:10.3390/antibiotics11101390

Tunisian Multicenter Study on the Prevalence of Colistin Resistance in Clinical Isolates of Gram Negative Bacilli: Emergence of Escherichia coli Harbouring the mcr-1 Gene

Antibiotics (Basel). 2022 Oct 11;11(10):1390. doi: 10.3390/antibiotics11101390.

Authors

Sana Ferjani¹, Elaa Maamar¹, Asma Ferjani^{1

2}, Khaoula Meftah³, Hager Battikh⁴, Besma Mnif^{5

6}, Manel Hamdoun^{7

8}, Yosra Chebbi^{9

10}, Lamia Kanzari^{1

2}, Wafa Achour^{9

10}, Olfa Bahri^{7

8}, Adenene Hammami^{5

6}, Meriam Zribi⁴, Hanen Smaoui³, Ilhem Boutiba-Ben Boubaker^{1

2}

Affiliations

¹ Faculty of Medicine of Tunis, University of Tunis El Manar, LR99ES09, Tunis Rue Djebal Lakhdar 1006, Tunisia.
² Charles Nicolle Hospital, Laboratory of Microbiology, Boulevard 9 April, Tunis 1006, Tunisia.
³ Laboratory of Microbiology, Children's Hospital of Tunis, Boulevard 9 April, Tunis 1006, Tunisia.
⁴ Microbiology Laboratory, Rabta University Hospital, Rue Jabbari, Tunis 1007, Tunisia.
⁵ Laboratory of Microbiology, Habib Bourguiba University Hospital, Route de l'Ain, Sfax 3000, Tunisia.
⁶ Research Laboratory for Microorganisms and Human Disease, University of Sfax, Avenue Majida Boulila, Sfax 3029, Tunisia.
⁷ Aziza Othmana Hospital, Laboratoire de Microbiologie-Biochimie, Bab Menara Tunis 1008, Tunisia.
⁸ Faculty of Medicine of Tunis, University of Tunis El Manar, LR16SP01, Tunis Rue Djebal Lakhdar 1006, Tunisia.
⁹ National Bone Marrow Transplant Center, Laboratory Ward, Tunis Rue Djebal Lakhdar 1006, Tunisia.
¹⁰ Faculty of Medicine of Tunis, Tunis El Manar University, LR18ES39, Tunis Rue Djebal Lakhdar 1006, Tunisia.

Abstract

Background: Actually, no data on the prevalence of plasmid colistin resistance in Tunisia are available among clinical bacteria.

Objectives: This study aimed to investigate the current epidemiology of colistin resistance and the spread of the mcr gene in clinical Gram-negative bacteria (GNB) isolated from six Tunisian university hospitals.

Methods: A total of 836 GNB strains were inoculated on COL-R agar plates with selective screening agar for the isolation of GNB resistant to colistin. For the selected isolates, mcr genes, beta-lactamases associated-resistance genes and molecular characterisation were screened by PCRs and sequencing.

Results: Colistin-resistance was detected in 5.02% (42/836) of the isolates and colistin-resistant isolates harboured an ESBL (bla_CTX-M-15) and/or a carbapenemase (bla_OXA-48, bla_VIM) encoding gene in 45.2% of the cases. The mcr-1 gene was detected in four E. coli isolates (0.59%) causing urinary tract infections and all these isolates also contained the bla_TEM-1 gene. The bla_CTX-M-15 gene was detected in three isolates that also carried the IncY and IncFIB replicons. The genetic environment surrounding the mcr-carrying plasmid indicated the presence of pap-2 gene upstream mcr-1 resistance marker with unusual missing of ISApl1 insertion sequence.

The conclusions: This study reports the first description of the mcr-1 gene among clinical E. coli isolates in Tunisia and provides an incentive to conduct routine colistin susceptibility testing in GNB clinical isolates.

Keywords: Gram negative bacteria; colistin resistance; mcr-1 gene; multi-drug resistant bacteria.

Grants and funding

This work was supported by the Ministry of Higher Education and Scientific Research of Tunisia.