Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022

Abstract Brucella melitensis is a zoonotic pathogen that poses a worldwide public health challenge. In recent years, whole-genome sequencing has become a widely accepted molecular typing method for the genomic epidemiology of brucellosis. This study reports the genomic characteristics of 24 B. melit...

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Main Authors: Boutheina Ksibi, Fahmi Smaoui, Nourelhouda Ben Ayed, Manel Guetat, Senda Mezghani, Sonia Ktari, Faouzia Mahjoubi, Mounir Ben Jemaa, Héla Karray, Adnene Hammami
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Language:English
Published: BMC 2025-02-01
Series:BMC Microbiology
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Online Access:https://doi.org/10.1186/s12866-025-03802-1
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author Boutheina Ksibi
Fahmi Smaoui
Nourelhouda Ben Ayed
Manel Guetat
Senda Mezghani
Sonia Ktari
Faouzia Mahjoubi
Mounir Ben Jemaa
Héla Karray
Adnene Hammami
author_facet Boutheina Ksibi
Fahmi Smaoui
Nourelhouda Ben Ayed
Manel Guetat
Senda Mezghani
Sonia Ktari
Faouzia Mahjoubi
Mounir Ben Jemaa
Héla Karray
Adnene Hammami
author_sort Boutheina Ksibi
collection DOAJ
description Abstract Brucella melitensis is a zoonotic pathogen that poses a worldwide public health challenge. In recent years, whole-genome sequencing has become a widely accepted molecular typing method for the genomic epidemiology of brucellosis. This study reports the genomic characteristics of 24 B. melitensis strains isolated from human infections in southern Tunisia over 35 years (1988–2022). We utilized WGS to analyze the clonal relationships of these strains, their relatedness to international sequences, their antimicrobial resistance determinants, and their virulence factors. Our findings revealed a high genetic stability over three decades. All isolates were identified as B. melitensis biovar 3 and were assigned to the same sequence type, ST11, using the MLST-9 scheme. Using the MLST-21, Tunisian sequences shared 20 out of 21 alleles and were assigned to 2 closely related STs (ST89 and ST114). Phylogenetic analysis indicated that all Tunisian sequences were grouped into a single subcluster within lineage I, the West Mediterranean clade, and were highly related to other strains from the Maghreb region (Morocco and Algeria). Antimicrobial resistance analysis revealed no classical resistance determinants. However, mprF, bepCDEFG genes, and missense mutations in rpoB, gyrA, gyrB, and parC genes were identified. Virulence analysis identified 67 genes, predominantly involved in lipopolysaccharide biosynthesis and the type IV secretion system. To our knowledge, this study represents the first genomic investigation of B. melitensis strains circulating in Tunisia. Our findings underscore the importance of genomic surveillance in understanding the epidemiology and evolution of brucellosis in North Africa.
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spelling doaj-art-929efdfc59f14d698a41cfd19c94a5e02025-08-20T02:01:35ZengBMCBMC Microbiology1471-21802025-02-012511910.1186/s12866-025-03802-1Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022Boutheina Ksibi0Fahmi Smaoui1Nourelhouda Ben Ayed2Manel Guetat3Senda Mezghani4Sonia Ktari5Faouzia Mahjoubi6Mounir Ben Jemaa7Héla Karray8Adnene Hammami9Research Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalLaboratory of Microbiology, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalInfectious Diseases Department, Hedi Chaker University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalResearch Laboratory Microorganisms and Human Disease “MPH LR03SP03”, Habib Bourguiba University HospitalAbstract Brucella melitensis is a zoonotic pathogen that poses a worldwide public health challenge. In recent years, whole-genome sequencing has become a widely accepted molecular typing method for the genomic epidemiology of brucellosis. This study reports the genomic characteristics of 24 B. melitensis strains isolated from human infections in southern Tunisia over 35 years (1988–2022). We utilized WGS to analyze the clonal relationships of these strains, their relatedness to international sequences, their antimicrobial resistance determinants, and their virulence factors. Our findings revealed a high genetic stability over three decades. All isolates were identified as B. melitensis biovar 3 and were assigned to the same sequence type, ST11, using the MLST-9 scheme. Using the MLST-21, Tunisian sequences shared 20 out of 21 alleles and were assigned to 2 closely related STs (ST89 and ST114). Phylogenetic analysis indicated that all Tunisian sequences were grouped into a single subcluster within lineage I, the West Mediterranean clade, and were highly related to other strains from the Maghreb region (Morocco and Algeria). Antimicrobial resistance analysis revealed no classical resistance determinants. However, mprF, bepCDEFG genes, and missense mutations in rpoB, gyrA, gyrB, and parC genes were identified. Virulence analysis identified 67 genes, predominantly involved in lipopolysaccharide biosynthesis and the type IV secretion system. To our knowledge, this study represents the first genomic investigation of B. melitensis strains circulating in Tunisia. Our findings underscore the importance of genomic surveillance in understanding the epidemiology and evolution of brucellosis in North Africa.https://doi.org/10.1186/s12866-025-03802-1Brucella melitensisTunisiaWGSEpidemiologyGenotyping
spellingShingle Boutheina Ksibi
Fahmi Smaoui
Nourelhouda Ben Ayed
Manel Guetat
Senda Mezghani
Sonia Ktari
Faouzia Mahjoubi
Mounir Ben Jemaa
Héla Karray
Adnene Hammami
Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
BMC Microbiology
Brucella melitensis
Tunisia
WGS
Epidemiology
Genotyping
title Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
title_full Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
title_fullStr Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
title_full_unstemmed Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
title_short Genomic analysis of Brucella melitensis isolates recovered from humans in south Tunisia over 35 years between 1988 and 2022
title_sort genomic analysis of brucella melitensis isolates recovered from humans in south tunisia over 35 years between 1988 and 2022
topic Brucella melitensis
Tunisia
WGS
Epidemiology
Genotyping
url https://doi.org/10.1186/s12866-025-03802-1
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