the analyses, because these data were only available for a limited number of patients. Using thes... more the analyses, because these data were only available for a limited number of patients. Using these limited albuminuria and proteinuria data would have caused substantial selection bias. Second, not all creatinine values were measured by the same laboratory or by the same creatinine assay due to the design of the database, which collects data from practices throughout Flanders. However, all Belgian laboratories are subject to quality control measures (
We determined an antibiotic resistance mechanism in the eastern region, KSA, and the genetic fact... more We determined an antibiotic resistance mechanism in the eastern region, KSA, and the genetic factor clonal relatedness within Gram-negative bacteria. During our retrospective study, a total number of 29 E. coli ESBL producer strains were isolated for patients visiting King Fahad Hospital, Al-Ahsa, KSA. The bla genes were detected via PCR and identified via sequencing. Associated plasmid-mediated quinolone resistance genes, as well as int1 and int2 genes, were also studied. Phylogenetic groups, the ST131 clone, virulence factors, and PFGE were also checked. The blaCTX-M-9 (3.7%), blaCTX-M-27 (22.2%), and blaCTX-M-15 (77.8%) genes were identified; however, the blaCMY-42 (7.4%) gene was recorded for the first time in KSA. The qnrS1 gene was found in 44.4% of strains, and among them, 50% concomitantly harbored the aac(6′)Ib-cr. The int1 gene was detected in 25.9% strains; nonetheless, the int2 gene was found in 7.4% of isolates. The strains belonged mainly to the B2 and D phylogroups. P...
Antimicrobial resistance represents a global health problem, with infections due to pathogenic an... more Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant ‘hotspots’ of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant ...
The Lattice Boltzmann Method (LBM) with double populations is applied to solve the steady-state l... more The Lattice Boltzmann Method (LBM) with double populations is applied to solve the steady-state laminar natural convective heat transfer in a triangular cavity filled with water. The bottom wall is heated, the vertical wall is cooled, and the inclined wall is kept adiabatic. The buoyancy effect was modeled by applying the Boussinesq approximation to the momentum equation. The fluid velocity is determined by D2Q9 LBM and the energy equation is discritized by D2Q4 LBM to compute the temperature field. Comparisons with previously published work are performed and found to be in excellent agreement. Numerical results are obtained for a wide range of parameters: the Rayleigh number from to and the inclination angle from 0° to 360°. Flow and thermal fields were exhibited by means of streamlines and isotherms. It is observed that inclination angle can be used as a relevant parameter to control heat transfer in right-angled triangular enclosures.
Aims Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it... more Aims Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it seems that rearing conditions have important impact on emergence and spread of antimicrobial-resistant bacteria. Thus, the authors sought to (1) assess the role of rabbits residing across diverse ecosystems as potential reservoirs of antimicrobial-resistant enterococci and (2) investigate the genetic background of detected resistances. Methods and Results Faecal samples from 60 healthy farmed rabbits (one farm), 35 laboratory rabbits and 31 wild rabbits were analysed. Overall, 97 enterococci isolates were accumulated, as follows: 44 E. faecium, 37 E. faecalis, 7 E. gallinarum, 5 E. durans and 4 E. avium. E. faecalis isolates were statistically associated with farm rabbits and wild rabbits (p < 0.05). High rates of resistance were observed for tetracycline (60.8%; tetM [n = 48; 81.3%], tetO [n = 7; 11.8%] and tetL [n = 1; 1.7%]), erythromycin (43.3%; msr(A) [n = 14; 33.3%] and ermB [n...
The present study investigated the colonization rates and antimicrobial susceptibility of Staphyl... more The present study investigated the colonization rates and antimicrobial susceptibility of Staphylococcus species isolated from the nostrils of healthy horses. A nonselective laboratory approach was applied, followed by confirmation using a Phoenix automated microbiological system. Among the 92 horses included in the study, 48.9% (45/92) carried Staphylococcus species of mostly the coagulase-negative staphylococci (CoNS) type yielding 70 Staphylococcus strains. Of these strains, 37.1% (26/70; 24 CoNS and 2 coagulasepositive staphylococci; CoPS) were identified as methicillin-resistant staphylococci (MRS) expressing significant resistance to important antimicrobial classes represented mainly by subspecies of CoNS. This is the first study reporting a high prevalence of various Staphylococcus species, particularly strains of CoNS expressing multidrug resistance patterns of public health concern, colonizing healthy horses in Libya.
Environmental Science and Pollution Research, 2020
Aquatic environments are crucial hotspots for the dissemination of antibiotic resistant microorga... more Aquatic environments are crucial hotspots for the dissemination of antibiotic resistant microorganisms and resistance genes. Thus, the purpose of this study was to investigate the occurrence and the genetic characterization of cefotaxime-resistant (CTX R) Enterobacteriaceae at a Tunisian semi-industrial pilot plant with biological treatment (WWPP) and its receiving river (Rouriche River, downstream from WWPP) located in Tunis City, during 2017-2018. We collected 105 and 15 water samples from the WWPP and the Rouriche River, respectively. Samples were screened to recover ESBL-producing Enterobacteriaceae (ESBL-E) and isolates were characterized for phenotype/genotype of antimicrobial resistance, integrons, plasmid types and molecular typing (multilocus sequence typing, MLST). Among 120 water samples, 33 and 4 contained ESBL-producing E. coli and K. pneumoniae isolates, respectively. Most isolates were multidrug resistant and produced CTX-M-15 (28 isolates), CTX-M-1 (4 isolates), CTX-M-55 (2 isolates), CTX-M-27 (one isolate), SHV-12 (one isolate) and VEB beta-lactamases (one isolate). All K. pneumoniae were CTX-M-15-positive. Four colistin-resistant isolates were found (MIC 4-8 μg/ml), but they were negative for the mcr genes tested. Class 1 integrons were detected in 21/25 trimethoprim/sulfamethoxazole-resistant isolates, and nine of them carried the gene cassette arrays: aadA2 + dfrA12 (n = 4), aadA1 + dfrA15 (n = 2), aadA5 + dfrA17 (n = 2) and aadA1/2 (n = 1). The IncP and IncFIB plasmids were found in 30 and 16 isolates, respectively. Genetic lineages detected were as follows: E. coli (ST48-ST10 Cplx, ST2499, ST906, ST2973 and ST2142); K. pneumoniae: (ST1540 and ST661). Our findings show a high rate of CTX-M-15 and high genetic diversity of ESBL-E isolates from WWPP and receiving river water.
International Journal of Environmental Health Research, 2020
The aim of this study was to compare the antibiotic susceptibility of eighty Escherichia coli iso... more The aim of this study was to compare the antibiotic susceptibility of eighty Escherichia coli isolates from vegetables and food products of animal origin in Tunisia, and to study their genes encoding antibiotic resistance and in vitro biofilm forming capacity. Antimicrobial susceptibilities were determined, as well as PCR investigation of genes associated with antibiotic resistance. Biofilm formation was tested using four different methods: the microtiter plate-, MTT-staining-, XTT-staining-, and the Congo Red Agar assays. High antibiotic resistance rates were observed for amoxicillin (68.7%), amoxicillin/clavulanic acid (73.7%), gentamicin (68.7%), kanamycin (66.2%), nalidixic acid (36.2%), streptomycin (68.7%) and tetracycline (35%). The majority of isolates was multidrug resistant and biofilm producer. MTT testing showed that vegetables isolates were significantly higher biofilm producers compared to foods of animal origins. This study showed that E. coli isolates from food products were reservoirs of genes encoding antibiotic-resistance and have a high propensity to produce biofilm.
Avian industries have been reported as an important contributor in the worldwide spread of antibi... more Avian industries have been reported as an important contributor in the worldwide spread of antibiotic resistance owing to some particular practices especially the overuse of antibiotics. Thus in this study, we aimed to characterize extended-spectrum-beta-lactamase (ESBL) and acquired-AmpC-beta-lactamase (aAmpC)-producing Escherichia coli isolates from chicken faeces and raw meat in Tunisia. During the year 2018, 286 faecal chicken swabs and 47 raw chicken meat samples were collected and processed to recover cefotaxime-resistant E. coli. Antimicrobial susceptibility was performed by disk-diffusion and/or broth-microdilution. bla TEM , bla SHV , bla CTX-M , and bla CMY genes were investigated by PCR/sequencing. Genes encoding resistance to colistin (mcr-1 to mcr-8), tetracycline (tetA/tetB), sulfonamide (sul1/sul3), and chloramphenicol (cmlA), were analysed by PCR. Class 1 integrons were investigated by PCR/sequencing. Phylogenetic groups of all isolates were determined. PFGE and MLST were performed for representative isolates. PCR-based replicon typing was performed in mcr1-harbouring isolates. Cefotaxime-resistant E. coli was detected in 22.4% (64/286) and 63.8% (30/47) of faeces and meat samples, respectively. Ninety isolates were ESBL-producers and harboured the genes: bla CTX-M-1 +/− bla TEM-1 (n = 65), bla CTX-M-55 +/− bla TEM-1 (n = 21), bla CTX-M-14 (n = 1), and bla SHV-12 (n = 3). The bla CMY-2 gene was detected in four ESBL-negative isolates. Isolates belonged to phylogroups D (50%), A (36.2%), B1 (9.6%), and B2 (4.3%). Fifty-four were colistin-resistant and 52 carried the mcr-1 gene. The tetA, sul1/sul3 and cmlA genes were detected among resistant isolates and 76 harboured class 1 integrons. MLST analysis revealed 13 sequence types (STs). The isolates were classified into 28 PFGE types. The IncP, IncFIB, and IncI1 replicons were detected among mcr-1-positive strains. We report a high frequency of ESBL-producers and colistin-resistant E. coli in chicken and derived food and the detection for the first time of bla CTX-M-55 in poultry in Tunisia.
Comparative Immunology, Microbiology and Infectious Diseases, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The present work reports a numerical study of natural convection in an incinerator shaped enclosu... more The present work reports a numerical study of natural convection in an incinerator shaped enclosure with a localized heated source situated at the bottom. Lattice Boltzmann Method (LBM) is used to simulate nanofluid (water-Al2O3) flow and heat transfer. Simulations have been carried out for the pertinent parameters: Rayleigh number (Ra=103−106), solid volume fraction relative heat source high ( ), relative heat source width ( ), and inclination angle of the incinerator ( ). The comparison of the obtained results is in excellent agreement with results from literature. It may be noted that the Rayleigh number, the solid volume fraction, the heat source tallness enhances the heat transfer and influences the flow pattern and the thermal structures. However for the relative heat source width plays opposite role for values superior to 0.4.
Objectives: Methicillin-resistant staphylococci, including methicillin-resistant Staphylococcus a... more Objectives: Methicillin-resistant staphylococci, including methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), pose a threat to animal and human health worldwide. Veterinary staff and pets may play a role in the spread of resistant clones. Methods: A total of 125 samples from veterinary staff (n = 50), dogs (n = 49) and cats (n = 26) were investigated. Obtained isolates were tested for the methicillin resistance gene mecA and were subjected to multiplex PCR to differentiate coagulase-positive species. Following SCCmec and spa typing, isolates were tested for the presence of various toxin and virulence genes and phenotypic resistance to common antimicrobials. Results: Overall, 4 MRSA were isolated from two veterinarians and two dogs and 19 MRSP were found in eleven dogs (12 isolates) and five cats (7 isolates). The MRSA isolates possessed sea (2) and eta (3) virulence genes and the MRSP isolates possessed sea (6), expA (15), expB (1) and siet (19) genes. SCCmec type II and three spa types (t186, t1816 and t10897) were identified in the MRSA isolates. Most of the MRSP isolates belonged to SCCmec types II (2 isolates) and V (10 isolates); however, the remaining 7 isolates were untypeable and contained class C1 mec. The majority of isolates were multidrug-resistant (MDR). Conclusion: These findings show that pets and veterinarians could be potential sources of MDR-MRSA and MDR-MRSP in Iran. Taken together, these findings warrant future investigations on the epidemiology and public-health significance of MDR-MRSA and MDR-MRSP both in veterinarians and companion animals in Iran.
is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This mi... more is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This microorganism can express a wide spectrum of pathogenic factors used to attach, colonize, invade and infect the host. The present study evaluated 120 isolates from eight different countries that were genotyped by RS-PCR and investigated for 26 different virulence factors to increase the knowledge on the circulating genetic lineages among the cow population with mastitis. New genotypes were observed for South African strains while for all the other countries new variants of existing genotypes were detected. For each country, a specific genotypic pattern was found. Among the virulence factors, , , and leucocidins genes were the most frequent. The and genes were present in seven out of eight countries; showed high frequency in South American countries (Brazil, Colombia, Argentina), while was harboured especially in one Mediterranean country (Tunisia). The , and genes were not detected in any ...
The Journal of Infection in Developing Countries, 2017
Introduction: The virulent Escherichia coli strains responsible for extraintestinal infections we... more Introduction: The virulent Escherichia coli strains responsible for extraintestinal infections were mainly belonged to B2 and D phylogroups. However, no past studies have determinate via the presence of virulence genes the frequency of E. coli pathovars recovered from animals housed in farms in Tunisia. The aims of this study were to investigate 26 E. coli isolated from healthy and diarrheic animals and to determinate via the presence of virulence genes the frequency of pathovars. Methodology: Twenty-six E. coli isolates of phylogroups B2 (n = 14), B22 (n = 9), B23 (n = 5), and D2 (n = 12) were characterized. Genes encoding virulence factors (fimH,eaeA,aggC,papC, papG allele III, hlyA, east1, cnf1, exhA,stx1, stx2, iutA, fyuA, ibeA,and ipaH), and antibiotic resistance as well as class 1 and 2 integrons were searched by polymerase chain reaction (PCR). The genetic relationship of isolates was done by PFGE. Results: According to the occurrence of specific genes the 26 isolates were cl...
Journal of microbiology, biotechnology and food sciences, 2016
Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce α... more Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce α-amylase and protease enzymes. The α-amylase activity showed an optimal activity at approximately 65°C and in wide pH interval ranging from 4 to 9. This enzyme was stable over the range of 45 to 70°C after 30 min of incubation and in the pH range of 8 to 10. Protease activity was optimal; at 80°C, pH 12. This enzyme was stable until 60°C over the pH range of 10 to 12. EDTA at concentration of 5 mM reduces slightly both activities evoking the serine alkaline protease. Cationic ions (Ca2+, Cu2+, Zn2+, and Mg 2+) have an inhibition effect on α-amylase. However, protease activity was enhanced by Ca2+, Cu2+ and Mg 2+); the other cations reduce slightly the proteolytic activity. SDS and H2O2 were found as inhibitors for both activities whereas Triton X-100 and perfume have no effect. Taken together, these traits make protease activity of B. licheniformis RBS 5 as efficient for use in detergent...
et caractérisation génotypique des Escherichia coli d'origine aviaire productrices de béta-la... more et caractérisation génotypique des Escherichia coli d'origine aviaire productrices de béta-lactamases à spectre étendu (BLSE) : sur le chemin mondiale de
Frontiers in Cellular and Infection Microbiology, 2015
Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal ... more Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal to human dissemination, via food chain or direct contact, of these resistant bacteria has been reported. In Tunisia, little is known about avian ESBL-producing E. coli and further studies are needed. Seventeen ESBL-producing Escherichia coli isolates from poultry feces from two farms (Farm 1 and farm 2) in the North of Tunisia have been used in this study. Eleven of these isolates (from farm 1) have the same resistance profile to nalidixic acid, sulfonamides, streptomycin, tetracycline, and norfloxacine (intermediately resistant). Out of the six isolates recovered from farm 2, only one was co-resistant to tetracycline. All isolates, except one, harbored bla CTX-M-1 gene, and one strain co-harbored the bla TEM-1 gene. The genes tetA and tetB were carried, respectively, by 11 and 1 amongst the 12 tetracycline-resistant isolates. Sulfonamides resistance was encoded by sul1, sul2, and sul3 genes in 3, 17, and 5 isolates, respectively. The qnrB1 was detected in nine strains, one of which co-harbored qnrS1 gene. The search for the class 1 and 2 integrons by PCR showed that in farm 1, class 1 and 2 integrons were found in one and ten isolates, respectively. In farm 2, class 1 integron was found in only one isolate, class 2 was not detected. Only one gene cassette arrangement was demonstrated in the variable regions (VR) of the 10 int2-positive isolates: dfrA1-sat2-aadA1. The size of the VR of the class 1 integron was approximately 250 bp in one int1-positive isolate, whereas in the second isolate, no amplification was observed. All isolates of farm 1 belong to the phylogroup A (sub-group A0). However, different types of phylogroups in farm 2 were detected. Each of the phylogroups A1, B2 2 , B2 3 was detected in one strain, while the D2 phylogroup was found in 3 isolates. The virulence genes iutA, fimH, and traT were detected in 3, 7, and 3 isolates, respectively. Two types of gene combination were detected: iutA+fimH+traT in 3 isolates and iutA+fimH in one isolate. The isolates recovered in farm 1 showed the same profile of PFGE macro-restriction, while isolates of farm 2 presented unrelated PFGE patterns. We conclude that these avian ESBL-producing E. coli isolates show homo-and heterogenic genetic background and that plasmids harboring ESBL genes could be involved in the dissemination of this resistance phenotype.
Bulletin de la Société de pathologie exotique (1990), 2004
The frequency of digestive colonization of neutropenic patients by Enterococci during the phase o... more The frequency of digestive colonization of neutropenic patients by Enterococci during the phase of pre-transplant and post-transplant of bone marrow is important indeed as 441 Enterococcus spp strains have been isolated from stool-cultures and other specimens whithin a period of 35 months in 80 patients. A quantitative stool culture was done on appropriate media. Simple bile-esculine agar (BE) and bile esculine-agar additionned with 6 mg/l of vancomycine (BEV) were used for detecting Enterococci. These organisms were taken into account, when then numeration was > 10(3) UFC/g of fecal sample on BE and in all cases on BEV. Species isolated were essentially Enterococcus faecalis (39.4%), Enterococcus faecium (34.4%) and Enterococcus casseliflavus (17%). These strains were characterized by a high frequency of high-level resistance to gentamicin (40.8%). Resistance to amoxicillin concerns 40% of E. faecium strains. Seventeen multiresistant strains of E. faecium isolated from 7 patient...
La production de slime, principal facteur de virulence de Staphylococcus epidermidis impliqué dan... more La production de slime, principal facteur de virulence de Staphylococcus epidermidis impliqué dans les infections liées aux cathéters veineux centraux, est codée par l'opéron icaADBC dont l'expression est sujette à une variation de phase. La transposition réversible de l'élément IS256 au niveau de cet opéron est l'un des mécanismes les plus important de cette variation. Notre étude a comparé 28 souches de S. epidermidis responsables d'infections liées aux cathéters à 28 souches de portage nasal concernant la détection de slime sur milieu rouge Congo, la recherche des gènes ica et de l'élément IS256 par PCR. L'opéron ica a été présent parmi toutes les souches productrices de slime, et absent parmi les souches slime négatif. Seules 79 % des souches porteuses des gènes ica ont été productrices de slime et aucune insertion de la séquence IS256 n'a été détectée dans les gènes ica. Une différence significative a été retrouvée entre souches responsables d'infection et souches de portage en termes de résistance à l'oxacilline (67,8 contre 35,7 %) et à l'ofloxacine (75 contre 35,7 %), de production de slime (64,2 contre 28,5 %), de phénotype variable (46,4 contre 7,1 %) et de présence des gènes ica (82,1 contre 35,7 %). Notre étude démontre le rôle des gènes ica, de la variabilité phénotypique de la production de biofilm et de la multirésistance aux antibiotiques comme facteurs de virulence des souches de S. epidermidis responsables d'infections liés aux cathéters ; elle confirme également la complexité et la diversité des mécanismes régulateurs intervenant au cours de la formation de biofilm.
the analyses, because these data were only available for a limited number of patients. Using thes... more the analyses, because these data were only available for a limited number of patients. Using these limited albuminuria and proteinuria data would have caused substantial selection bias. Second, not all creatinine values were measured by the same laboratory or by the same creatinine assay due to the design of the database, which collects data from practices throughout Flanders. However, all Belgian laboratories are subject to quality control measures (
We determined an antibiotic resistance mechanism in the eastern region, KSA, and the genetic fact... more We determined an antibiotic resistance mechanism in the eastern region, KSA, and the genetic factor clonal relatedness within Gram-negative bacteria. During our retrospective study, a total number of 29 E. coli ESBL producer strains were isolated for patients visiting King Fahad Hospital, Al-Ahsa, KSA. The bla genes were detected via PCR and identified via sequencing. Associated plasmid-mediated quinolone resistance genes, as well as int1 and int2 genes, were also studied. Phylogenetic groups, the ST131 clone, virulence factors, and PFGE were also checked. The blaCTX-M-9 (3.7%), blaCTX-M-27 (22.2%), and blaCTX-M-15 (77.8%) genes were identified; however, the blaCMY-42 (7.4%) gene was recorded for the first time in KSA. The qnrS1 gene was found in 44.4% of strains, and among them, 50% concomitantly harbored the aac(6′)Ib-cr. The int1 gene was detected in 25.9% strains; nonetheless, the int2 gene was found in 7.4% of isolates. The strains belonged mainly to the B2 and D phylogroups. P...
Antimicrobial resistance represents a global health problem, with infections due to pathogenic an... more Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant ‘hotspots’ of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant ...
The Lattice Boltzmann Method (LBM) with double populations is applied to solve the steady-state l... more The Lattice Boltzmann Method (LBM) with double populations is applied to solve the steady-state laminar natural convective heat transfer in a triangular cavity filled with water. The bottom wall is heated, the vertical wall is cooled, and the inclined wall is kept adiabatic. The buoyancy effect was modeled by applying the Boussinesq approximation to the momentum equation. The fluid velocity is determined by D2Q9 LBM and the energy equation is discritized by D2Q4 LBM to compute the temperature field. Comparisons with previously published work are performed and found to be in excellent agreement. Numerical results are obtained for a wide range of parameters: the Rayleigh number from to and the inclination angle from 0° to 360°. Flow and thermal fields were exhibited by means of streamlines and isotherms. It is observed that inclination angle can be used as a relevant parameter to control heat transfer in right-angled triangular enclosures.
Aims Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it... more Aims Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it seems that rearing conditions have important impact on emergence and spread of antimicrobial-resistant bacteria. Thus, the authors sought to (1) assess the role of rabbits residing across diverse ecosystems as potential reservoirs of antimicrobial-resistant enterococci and (2) investigate the genetic background of detected resistances. Methods and Results Faecal samples from 60 healthy farmed rabbits (one farm), 35 laboratory rabbits and 31 wild rabbits were analysed. Overall, 97 enterococci isolates were accumulated, as follows: 44 E. faecium, 37 E. faecalis, 7 E. gallinarum, 5 E. durans and 4 E. avium. E. faecalis isolates were statistically associated with farm rabbits and wild rabbits (p < 0.05). High rates of resistance were observed for tetracycline (60.8%; tetM [n = 48; 81.3%], tetO [n = 7; 11.8%] and tetL [n = 1; 1.7%]), erythromycin (43.3%; msr(A) [n = 14; 33.3%] and ermB [n...
The present study investigated the colonization rates and antimicrobial susceptibility of Staphyl... more The present study investigated the colonization rates and antimicrobial susceptibility of Staphylococcus species isolated from the nostrils of healthy horses. A nonselective laboratory approach was applied, followed by confirmation using a Phoenix automated microbiological system. Among the 92 horses included in the study, 48.9% (45/92) carried Staphylococcus species of mostly the coagulase-negative staphylococci (CoNS) type yielding 70 Staphylococcus strains. Of these strains, 37.1% (26/70; 24 CoNS and 2 coagulasepositive staphylococci; CoPS) were identified as methicillin-resistant staphylococci (MRS) expressing significant resistance to important antimicrobial classes represented mainly by subspecies of CoNS. This is the first study reporting a high prevalence of various Staphylococcus species, particularly strains of CoNS expressing multidrug resistance patterns of public health concern, colonizing healthy horses in Libya.
Environmental Science and Pollution Research, 2020
Aquatic environments are crucial hotspots for the dissemination of antibiotic resistant microorga... more Aquatic environments are crucial hotspots for the dissemination of antibiotic resistant microorganisms and resistance genes. Thus, the purpose of this study was to investigate the occurrence and the genetic characterization of cefotaxime-resistant (CTX R) Enterobacteriaceae at a Tunisian semi-industrial pilot plant with biological treatment (WWPP) and its receiving river (Rouriche River, downstream from WWPP) located in Tunis City, during 2017-2018. We collected 105 and 15 water samples from the WWPP and the Rouriche River, respectively. Samples were screened to recover ESBL-producing Enterobacteriaceae (ESBL-E) and isolates were characterized for phenotype/genotype of antimicrobial resistance, integrons, plasmid types and molecular typing (multilocus sequence typing, MLST). Among 120 water samples, 33 and 4 contained ESBL-producing E. coli and K. pneumoniae isolates, respectively. Most isolates were multidrug resistant and produced CTX-M-15 (28 isolates), CTX-M-1 (4 isolates), CTX-M-55 (2 isolates), CTX-M-27 (one isolate), SHV-12 (one isolate) and VEB beta-lactamases (one isolate). All K. pneumoniae were CTX-M-15-positive. Four colistin-resistant isolates were found (MIC 4-8 μg/ml), but they were negative for the mcr genes tested. Class 1 integrons were detected in 21/25 trimethoprim/sulfamethoxazole-resistant isolates, and nine of them carried the gene cassette arrays: aadA2 + dfrA12 (n = 4), aadA1 + dfrA15 (n = 2), aadA5 + dfrA17 (n = 2) and aadA1/2 (n = 1). The IncP and IncFIB plasmids were found in 30 and 16 isolates, respectively. Genetic lineages detected were as follows: E. coli (ST48-ST10 Cplx, ST2499, ST906, ST2973 and ST2142); K. pneumoniae: (ST1540 and ST661). Our findings show a high rate of CTX-M-15 and high genetic diversity of ESBL-E isolates from WWPP and receiving river water.
International Journal of Environmental Health Research, 2020
The aim of this study was to compare the antibiotic susceptibility of eighty Escherichia coli iso... more The aim of this study was to compare the antibiotic susceptibility of eighty Escherichia coli isolates from vegetables and food products of animal origin in Tunisia, and to study their genes encoding antibiotic resistance and in vitro biofilm forming capacity. Antimicrobial susceptibilities were determined, as well as PCR investigation of genes associated with antibiotic resistance. Biofilm formation was tested using four different methods: the microtiter plate-, MTT-staining-, XTT-staining-, and the Congo Red Agar assays. High antibiotic resistance rates were observed for amoxicillin (68.7%), amoxicillin/clavulanic acid (73.7%), gentamicin (68.7%), kanamycin (66.2%), nalidixic acid (36.2%), streptomycin (68.7%) and tetracycline (35%). The majority of isolates was multidrug resistant and biofilm producer. MTT testing showed that vegetables isolates were significantly higher biofilm producers compared to foods of animal origins. This study showed that E. coli isolates from food products were reservoirs of genes encoding antibiotic-resistance and have a high propensity to produce biofilm.
Avian industries have been reported as an important contributor in the worldwide spread of antibi... more Avian industries have been reported as an important contributor in the worldwide spread of antibiotic resistance owing to some particular practices especially the overuse of antibiotics. Thus in this study, we aimed to characterize extended-spectrum-beta-lactamase (ESBL) and acquired-AmpC-beta-lactamase (aAmpC)-producing Escherichia coli isolates from chicken faeces and raw meat in Tunisia. During the year 2018, 286 faecal chicken swabs and 47 raw chicken meat samples were collected and processed to recover cefotaxime-resistant E. coli. Antimicrobial susceptibility was performed by disk-diffusion and/or broth-microdilution. bla TEM , bla SHV , bla CTX-M , and bla CMY genes were investigated by PCR/sequencing. Genes encoding resistance to colistin (mcr-1 to mcr-8), tetracycline (tetA/tetB), sulfonamide (sul1/sul3), and chloramphenicol (cmlA), were analysed by PCR. Class 1 integrons were investigated by PCR/sequencing. Phylogenetic groups of all isolates were determined. PFGE and MLST were performed for representative isolates. PCR-based replicon typing was performed in mcr1-harbouring isolates. Cefotaxime-resistant E. coli was detected in 22.4% (64/286) and 63.8% (30/47) of faeces and meat samples, respectively. Ninety isolates were ESBL-producers and harboured the genes: bla CTX-M-1 +/− bla TEM-1 (n = 65), bla CTX-M-55 +/− bla TEM-1 (n = 21), bla CTX-M-14 (n = 1), and bla SHV-12 (n = 3). The bla CMY-2 gene was detected in four ESBL-negative isolates. Isolates belonged to phylogroups D (50%), A (36.2%), B1 (9.6%), and B2 (4.3%). Fifty-four were colistin-resistant and 52 carried the mcr-1 gene. The tetA, sul1/sul3 and cmlA genes were detected among resistant isolates and 76 harboured class 1 integrons. MLST analysis revealed 13 sequence types (STs). The isolates were classified into 28 PFGE types. The IncP, IncFIB, and IncI1 replicons were detected among mcr-1-positive strains. We report a high frequency of ESBL-producers and colistin-resistant E. coli in chicken and derived food and the detection for the first time of bla CTX-M-55 in poultry in Tunisia.
Comparative Immunology, Microbiology and Infectious Diseases, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The present work reports a numerical study of natural convection in an incinerator shaped enclosu... more The present work reports a numerical study of natural convection in an incinerator shaped enclosure with a localized heated source situated at the bottom. Lattice Boltzmann Method (LBM) is used to simulate nanofluid (water-Al2O3) flow and heat transfer. Simulations have been carried out for the pertinent parameters: Rayleigh number (Ra=103−106), solid volume fraction relative heat source high ( ), relative heat source width ( ), and inclination angle of the incinerator ( ). The comparison of the obtained results is in excellent agreement with results from literature. It may be noted that the Rayleigh number, the solid volume fraction, the heat source tallness enhances the heat transfer and influences the flow pattern and the thermal structures. However for the relative heat source width plays opposite role for values superior to 0.4.
Objectives: Methicillin-resistant staphylococci, including methicillin-resistant Staphylococcus a... more Objectives: Methicillin-resistant staphylococci, including methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP), pose a threat to animal and human health worldwide. Veterinary staff and pets may play a role in the spread of resistant clones. Methods: A total of 125 samples from veterinary staff (n = 50), dogs (n = 49) and cats (n = 26) were investigated. Obtained isolates were tested for the methicillin resistance gene mecA and were subjected to multiplex PCR to differentiate coagulase-positive species. Following SCCmec and spa typing, isolates were tested for the presence of various toxin and virulence genes and phenotypic resistance to common antimicrobials. Results: Overall, 4 MRSA were isolated from two veterinarians and two dogs and 19 MRSP were found in eleven dogs (12 isolates) and five cats (7 isolates). The MRSA isolates possessed sea (2) and eta (3) virulence genes and the MRSP isolates possessed sea (6), expA (15), expB (1) and siet (19) genes. SCCmec type II and three spa types (t186, t1816 and t10897) were identified in the MRSA isolates. Most of the MRSP isolates belonged to SCCmec types II (2 isolates) and V (10 isolates); however, the remaining 7 isolates were untypeable and contained class C1 mec. The majority of isolates were multidrug-resistant (MDR). Conclusion: These findings show that pets and veterinarians could be potential sources of MDR-MRSA and MDR-MRSP in Iran. Taken together, these findings warrant future investigations on the epidemiology and public-health significance of MDR-MRSA and MDR-MRSP both in veterinarians and companion animals in Iran.
is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This mi... more is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This microorganism can express a wide spectrum of pathogenic factors used to attach, colonize, invade and infect the host. The present study evaluated 120 isolates from eight different countries that were genotyped by RS-PCR and investigated for 26 different virulence factors to increase the knowledge on the circulating genetic lineages among the cow population with mastitis. New genotypes were observed for South African strains while for all the other countries new variants of existing genotypes were detected. For each country, a specific genotypic pattern was found. Among the virulence factors, , , and leucocidins genes were the most frequent. The and genes were present in seven out of eight countries; showed high frequency in South American countries (Brazil, Colombia, Argentina), while was harboured especially in one Mediterranean country (Tunisia). The , and genes were not detected in any ...
The Journal of Infection in Developing Countries, 2017
Introduction: The virulent Escherichia coli strains responsible for extraintestinal infections we... more Introduction: The virulent Escherichia coli strains responsible for extraintestinal infections were mainly belonged to B2 and D phylogroups. However, no past studies have determinate via the presence of virulence genes the frequency of E. coli pathovars recovered from animals housed in farms in Tunisia. The aims of this study were to investigate 26 E. coli isolated from healthy and diarrheic animals and to determinate via the presence of virulence genes the frequency of pathovars. Methodology: Twenty-six E. coli isolates of phylogroups B2 (n = 14), B22 (n = 9), B23 (n = 5), and D2 (n = 12) were characterized. Genes encoding virulence factors (fimH,eaeA,aggC,papC, papG allele III, hlyA, east1, cnf1, exhA,stx1, stx2, iutA, fyuA, ibeA,and ipaH), and antibiotic resistance as well as class 1 and 2 integrons were searched by polymerase chain reaction (PCR). The genetic relationship of isolates was done by PFGE. Results: According to the occurrence of specific genes the 26 isolates were cl...
Journal of microbiology, biotechnology and food sciences, 2016
Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce α... more Bacillus licheniformis RBS 5 was isolated from thermal spring in Tunisia. The isolate coproduce α-amylase and protease enzymes. The α-amylase activity showed an optimal activity at approximately 65°C and in wide pH interval ranging from 4 to 9. This enzyme was stable over the range of 45 to 70°C after 30 min of incubation and in the pH range of 8 to 10. Protease activity was optimal; at 80°C, pH 12. This enzyme was stable until 60°C over the pH range of 10 to 12. EDTA at concentration of 5 mM reduces slightly both activities evoking the serine alkaline protease. Cationic ions (Ca2+, Cu2+, Zn2+, and Mg 2+) have an inhibition effect on α-amylase. However, protease activity was enhanced by Ca2+, Cu2+ and Mg 2+); the other cations reduce slightly the proteolytic activity. SDS and H2O2 were found as inhibitors for both activities whereas Triton X-100 and perfume have no effect. Taken together, these traits make protease activity of B. licheniformis RBS 5 as efficient for use in detergent...
et caractérisation génotypique des Escherichia coli d'origine aviaire productrices de béta-la... more et caractérisation génotypique des Escherichia coli d'origine aviaire productrices de béta-lactamases à spectre étendu (BLSE) : sur le chemin mondiale de
Frontiers in Cellular and Infection Microbiology, 2015
Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal ... more Avian ESBL-producing Escherichia coli isolates have been increasingly reported worldwide. Animal to human dissemination, via food chain or direct contact, of these resistant bacteria has been reported. In Tunisia, little is known about avian ESBL-producing E. coli and further studies are needed. Seventeen ESBL-producing Escherichia coli isolates from poultry feces from two farms (Farm 1 and farm 2) in the North of Tunisia have been used in this study. Eleven of these isolates (from farm 1) have the same resistance profile to nalidixic acid, sulfonamides, streptomycin, tetracycline, and norfloxacine (intermediately resistant). Out of the six isolates recovered from farm 2, only one was co-resistant to tetracycline. All isolates, except one, harbored bla CTX-M-1 gene, and one strain co-harbored the bla TEM-1 gene. The genes tetA and tetB were carried, respectively, by 11 and 1 amongst the 12 tetracycline-resistant isolates. Sulfonamides resistance was encoded by sul1, sul2, and sul3 genes in 3, 17, and 5 isolates, respectively. The qnrB1 was detected in nine strains, one of which co-harbored qnrS1 gene. The search for the class 1 and 2 integrons by PCR showed that in farm 1, class 1 and 2 integrons were found in one and ten isolates, respectively. In farm 2, class 1 integron was found in only one isolate, class 2 was not detected. Only one gene cassette arrangement was demonstrated in the variable regions (VR) of the 10 int2-positive isolates: dfrA1-sat2-aadA1. The size of the VR of the class 1 integron was approximately 250 bp in one int1-positive isolate, whereas in the second isolate, no amplification was observed. All isolates of farm 1 belong to the phylogroup A (sub-group A0). However, different types of phylogroups in farm 2 were detected. Each of the phylogroups A1, B2 2 , B2 3 was detected in one strain, while the D2 phylogroup was found in 3 isolates. The virulence genes iutA, fimH, and traT were detected in 3, 7, and 3 isolates, respectively. Two types of gene combination were detected: iutA+fimH+traT in 3 isolates and iutA+fimH in one isolate. The isolates recovered in farm 1 showed the same profile of PFGE macro-restriction, while isolates of farm 2 presented unrelated PFGE patterns. We conclude that these avian ESBL-producing E. coli isolates show homo-and heterogenic genetic background and that plasmids harboring ESBL genes could be involved in the dissemination of this resistance phenotype.
Bulletin de la Société de pathologie exotique (1990), 2004
The frequency of digestive colonization of neutropenic patients by Enterococci during the phase o... more The frequency of digestive colonization of neutropenic patients by Enterococci during the phase of pre-transplant and post-transplant of bone marrow is important indeed as 441 Enterococcus spp strains have been isolated from stool-cultures and other specimens whithin a period of 35 months in 80 patients. A quantitative stool culture was done on appropriate media. Simple bile-esculine agar (BE) and bile esculine-agar additionned with 6 mg/l of vancomycine (BEV) were used for detecting Enterococci. These organisms were taken into account, when then numeration was > 10(3) UFC/g of fecal sample on BE and in all cases on BEV. Species isolated were essentially Enterococcus faecalis (39.4%), Enterococcus faecium (34.4%) and Enterococcus casseliflavus (17%). These strains were characterized by a high frequency of high-level resistance to gentamicin (40.8%). Resistance to amoxicillin concerns 40% of E. faecium strains. Seventeen multiresistant strains of E. faecium isolated from 7 patient...
La production de slime, principal facteur de virulence de Staphylococcus epidermidis impliqué dan... more La production de slime, principal facteur de virulence de Staphylococcus epidermidis impliqué dans les infections liées aux cathéters veineux centraux, est codée par l'opéron icaADBC dont l'expression est sujette à une variation de phase. La transposition réversible de l'élément IS256 au niveau de cet opéron est l'un des mécanismes les plus important de cette variation. Notre étude a comparé 28 souches de S. epidermidis responsables d'infections liées aux cathéters à 28 souches de portage nasal concernant la détection de slime sur milieu rouge Congo, la recherche des gènes ica et de l'élément IS256 par PCR. L'opéron ica a été présent parmi toutes les souches productrices de slime, et absent parmi les souches slime négatif. Seules 79 % des souches porteuses des gènes ica ont été productrices de slime et aucune insertion de la séquence IS256 n'a été détectée dans les gènes ica. Une différence significative a été retrouvée entre souches responsables d'infection et souches de portage en termes de résistance à l'oxacilline (67,8 contre 35,7 %) et à l'ofloxacine (75 contre 35,7 %), de production de slime (64,2 contre 28,5 %), de phénotype variable (46,4 contre 7,1 %) et de présence des gènes ica (82,1 contre 35,7 %). Notre étude démontre le rôle des gènes ica, de la variabilité phénotypique de la production de biofilm et de la multirésistance aux antibiotiques comme facteurs de virulence des souches de S. epidermidis responsables d'infections liés aux cathéters ; elle confirme également la complexité et la diversité des mécanismes régulateurs intervenant au cours de la formation de biofilm.
Uploads
Papers by Salah Abbassi