Ahlem Jouini - Academia.edu (original) (raw)

Papers by Ahlem Jouini

Research paper thumbnail of Diversity of Genetic Lineages Among CTX-M-15 and CTX-M-14 Producing Escherichia coli Strains in a Tunisian Hospital

Current Microbiology, 2011

Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between ... more Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between June and December 2007 in a Tunisian hospital. Genes encoding extended-spectrum-beta-lactamases (ESBL) and other resistance genes were characterized by PCR and sequencing. The following ESBL genes were identified: bla CTX-M-15 (12 isolates), bla CTX-M-14a (one isolate), and bla CTX-M-14b (one isolate). The bla OXA-1 gene was detected in 13 bla CTX-Mproducing strains and a bla TEM-1 gene in 6 of them. The ISEcp1 sequence was found upstream of bla CTX-M genes in 8 of 14 strains, and orf477 or IS903 downstream of this gene in 13 strains. Nine of the strains carried class 1 integrons and five different gene cassette arrangements were detected, dfrA17-aadA5 being the most common. One of the strains (bla CTX-M-14a -positive) harbored three class 1 integrons, and one of them was non-previously described containing as gene cassettes new variants of aac(6 0 )-Ib and cmlA1 genes and it was linked to the bla CTX-M-14a gene flanked by a truncated ISEcp1 sequence (included in GenBank with accession number JF701188). CTX-M-15producing strains were ascribed to phylogroup B2 (six isolates) and D (six isolates). Multilocus-sequence-typing revealed ten different sequence-types (STs) among ESBLpositive E. coli strains with prevalence of ST405 (four strains of phylogroup D) and ST131 types (two strains of phylogroup B2 and serogroup O25b). A high clonal diversity was also observed among studied strains by pulsed-field-gel-electrophoresis (11 unrelated profiles). CTX-M-15 is an emergent mechanism of resistance in the studied hospital and the world-disseminated 0:25b-ST131-B2 and ST405-D clones have been identified among CTX-M-15-producing isolates.

Research paper thumbnail of Nasal carriage of Staphylococcus aureus in healthy humans with different levels of contact with animals in Tunisia: genetic lineages, methicillin resistance, and virulence factors

European Journal of Clinical Microbiology & Infectious Diseases, 2011

Nasal swabs of 423 healthy humans who showed different levels of contact with animals (frequent, ... more Nasal swabs of 423 healthy humans who showed different levels of contact with animals (frequent, 168; sporadic, 94; no contact, 161) were obtained in Tunisia (2008)(2009), and 99 of them presented other associated risk factors. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in one of these 423 samples (0.24%), retrieved from a veterinarian. The MRSA isolate was mecA-positive, typed as ST80-t203-SCCmecIVc-agrIII, and contained tet(K), ant(6)-Ia, and aph(3′)-IIIa genes encoding tetracycline, streptomycin, and kanamycin resistance, respectively. This MRSA isolate also contained the lukF/lukS virulence gene encoding Panton-Valentine leukocidin. Fifty-four (12.8%) additional nasal samples contained methicillin-susceptible S. aureus (MSSA) and one isolate/sample was characterized. A high diversity of spa types (n=43; 4 new) and pulsed-field gel electrophoresis (PFGE) types (n=37) was detected among the 55 recovered S. aureus strains. The percentages of antimicrobial resistance/detected resistance genes were as follows:

Research paper thumbnail of Prevalence and characterization of extended-spectrum β -lactamase-producing clinical Salmonella enterica isolates in Dakar, Senegal, from 1999 to 2009

Clinical Microbiology and Infection, 2014

Research paper thumbnail of Evaluation of various serum and animal protein free media for the production of a veterinary rabies vaccine in BHK-21 cells

Journal of Biotechnology, 2002

We have carried out the adaptation of BHK-21 cells to two serum free (Ex Cell 520 and HyQ PF CHO)... more We have carried out the adaptation of BHK-21 cells to two serum free (Ex Cell 520 and HyQ PF CHO) and three animal protein free media: Ex Cell 302, HyQ PF CHO MPS and Rencyte BHK. After a direct switch or a gradual adaptation, we have achieved BHK-21 cells growth in the following media: HyQ PF CHO, HyQ PF CHO MPS, Rencyte BHK and Ex Cell 302. The most suitable media for BHK-21 cells growth, with respect to cell density and specific growth rate, were HyQ PF CHO and HyQ PF CHO MPS. Hence we have selected these media to study cell growth and the production of rabies virus. Kinetic studies of cell growth in spinner flasks using the selected media have shown that a maximal cell density of 2 × 10 6 cells ml − 1 was reached in both media. For rabies virus production, the viral titer obtained was 1.7 ×10 6 FFU ml − 1 in HyQ PF CHO as well as in HyQ PF CHO MPS medium. The optimization of rabies virus production by BHK-21 cells grown in a 2 l bioreactor using the selected media, pointed to the following parameters: culture mode, perfusion rate and multiplicity of infection (MOI), as being the critical factors for achieving a good virus yield. When tested in mice, the activity of the experimental vaccines prepared on HyQ PF CHO MPS medium has shown a protective activity that meets WHO requirements.

Research paper thumbnail of Characterization of CTX-M and SHV extended-spectrum  -lactamases and associated resistance genes in Escherichia coli strains of food samples in Tunisia

Journal of Antimicrobial Chemotherapy, 2007

Objectives: To assess the occurrence of extended-spectrum b-lactamases (ESBLs) in Escherichia col... more Objectives: To assess the occurrence of extended-spectrum b-lactamases (ESBLs) in Escherichia coli isolates of faecal samples of animals (n 5 40) and food samples (n 5 38) obtained in Tunisia in 2006, and to characterize the type of ESBLs, their genetic environments and the associated resistance genes.

Research paper thumbnail of Diversity of Genetic Lineages Among CTX-M-15 and CTX-M-14 Producing Escherichia coli Strains in a Tunisian Hospital

Current Microbiology, 2011

Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between ... more Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between June and December 2007 in a Tunisian hospital. Genes encoding extended-spectrum-beta-lactamases (ESBL) and other resistance genes were characterized by PCR and sequencing. The following ESBL genes were identified: bla CTX-M-15 (12 isolates), bla CTX-M-14a (one isolate), and bla CTX-M-14b (one isolate). The bla OXA-1 gene was detected in 13 bla CTX-Mproducing strains and a bla TEM-1 gene in 6 of them. The ISEcp1 sequence was found upstream of bla CTX-M genes in 8 of 14 strains, and orf477 or IS903 downstream of this gene in 13 strains. Nine of the strains carried class 1 integrons and five different gene cassette arrangements were detected, dfrA17-aadA5 being the most common. One of the strains (bla CTX-M-14a -positive) harbored three class 1 integrons, and one of them was non-previously described containing as gene cassettes new variants of aac(6 0 )-Ib and cmlA1 genes and it was linked to the bla CTX-M-14a gene flanked by a truncated ISEcp1 sequence (included in GenBank with accession number JF701188). CTX-M-15producing strains were ascribed to phylogroup B2 (six isolates) and D (six isolates). Multilocus-sequence-typing revealed ten different sequence-types (STs) among ESBLpositive E. coli strains with prevalence of ST405 (four strains of phylogroup D) and ST131 types (two strains of phylogroup B2 and serogroup O25b). A high clonal diversity was also observed among studied strains by pulsed-field-gel-electrophoresis (11 unrelated profiles). CTX-M-15 is an emergent mechanism of resistance in the studied hospital and the world-disseminated 0:25b-ST131-B2 and ST405-D clones have been identified among CTX-M-15-producing isolates.

Research paper thumbnail of Nasal carriage of Staphylococcus aureus in healthy humans with different levels of contact with animals in Tunisia: genetic lineages, methicillin resistance, and virulence factors

European Journal of Clinical Microbiology & Infectious Diseases, 2011

Nasal swabs of 423 healthy humans who showed different levels of contact with animals (frequent, ... more Nasal swabs of 423 healthy humans who showed different levels of contact with animals (frequent, 168; sporadic, 94; no contact, 161) were obtained in Tunisia (2008)(2009), and 99 of them presented other associated risk factors. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in one of these 423 samples (0.24%), retrieved from a veterinarian. The MRSA isolate was mecA-positive, typed as ST80-t203-SCCmecIVc-agrIII, and contained tet(K), ant(6)-Ia, and aph(3′)-IIIa genes encoding tetracycline, streptomycin, and kanamycin resistance, respectively. This MRSA isolate also contained the lukF/lukS virulence gene encoding Panton-Valentine leukocidin. Fifty-four (12.8%) additional nasal samples contained methicillin-susceptible S. aureus (MSSA) and one isolate/sample was characterized. A high diversity of spa types (n=43; 4 new) and pulsed-field gel electrophoresis (PFGE) types (n=37) was detected among the 55 recovered S. aureus strains. The percentages of antimicrobial resistance/detected resistance genes were as follows:

Research paper thumbnail of Prevalence and characterization of extended-spectrum β -lactamase-producing clinical Salmonella enterica isolates in Dakar, Senegal, from 1999 to 2009

Clinical Microbiology and Infection, 2014

Research paper thumbnail of Evaluation of various serum and animal protein free media for the production of a veterinary rabies vaccine in BHK-21 cells

Journal of Biotechnology, 2002

We have carried out the adaptation of BHK-21 cells to two serum free (Ex Cell 520 and HyQ PF CHO)... more We have carried out the adaptation of BHK-21 cells to two serum free (Ex Cell 520 and HyQ PF CHO) and three animal protein free media: Ex Cell 302, HyQ PF CHO MPS and Rencyte BHK. After a direct switch or a gradual adaptation, we have achieved BHK-21 cells growth in the following media: HyQ PF CHO, HyQ PF CHO MPS, Rencyte BHK and Ex Cell 302. The most suitable media for BHK-21 cells growth, with respect to cell density and specific growth rate, were HyQ PF CHO and HyQ PF CHO MPS. Hence we have selected these media to study cell growth and the production of rabies virus. Kinetic studies of cell growth in spinner flasks using the selected media have shown that a maximal cell density of 2 × 10 6 cells ml − 1 was reached in both media. For rabies virus production, the viral titer obtained was 1.7 ×10 6 FFU ml − 1 in HyQ PF CHO as well as in HyQ PF CHO MPS medium. The optimization of rabies virus production by BHK-21 cells grown in a 2 l bioreactor using the selected media, pointed to the following parameters: culture mode, perfusion rate and multiplicity of infection (MOI), as being the critical factors for achieving a good virus yield. When tested in mice, the activity of the experimental vaccines prepared on HyQ PF CHO MPS medium has shown a protective activity that meets WHO requirements.

Research paper thumbnail of Characterization of CTX-M and SHV extended-spectrum  -lactamases and associated resistance genes in Escherichia coli strains of food samples in Tunisia

Journal of Antimicrobial Chemotherapy, 2007

Objectives: To assess the occurrence of extended-spectrum b-lactamases (ESBLs) in Escherichia col... more Objectives: To assess the occurrence of extended-spectrum b-lactamases (ESBLs) in Escherichia coli isolates of faecal samples of animals (n 5 40) and food samples (n 5 38) obtained in Tunisia in 2006, and to characterize the type of ESBLs, their genetic environments and the associated resistance genes.