Olivier Denis
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Olivier Denis has a total of 82 co-authors. Here are the top co-authors by number of shared publications:
Claire Nonhoff
Université Libre de Bruxelles (ULB), Hôpital Erasme, Brussels, Belgium
8 shared publicationsMarc J. Struelens
Laboratoire de Référence MRSA-Staphylocoques, Department of Microbiology, Hôpital Erasme, Université Libre de Bruxelles, Brussels , Belgium 2 Unité d'Epidémiologie des Maladies Infectieuses, Ecole de Santé Publique, Université Libre de Bruxelles, Brussels , Belgium
8 shared publicationsAriane Deplano
Laboratoire de Référence MRSA-Staphylocoques, Department of Microbiology, Hôpital Erasme, Université Libre de Bruxelles, Brussels , Belgium
5 shared publicationsRaf De Ryck
Laboratoire de Référence MRSA-Staphylocoques, Department of Microbiology, Hôpital Erasme, Université Libre de Bruxelles, Brussels , Belgium
4 shared publications- Isabel Montesinos
Microbiology Department, Cliniques Universitaires Saint Luc, Université Catholique de Louvain, 1200 Brussels, Belgium
3 shared publications M. J. Struelens
Universite Libre de Bruxelles
3 shared publications
Latest Publications
- Open Access
- 29 June 2026
- Published by MDPI AG in Preprints.org
Mapping Antibiotic-Use Pathways and Leverage Points for AMR Control in Kinshasa’s Pig and Poultry Systems: A One Health Stakeholder Analysis
Antimicrobial resistance (AMR) is a major global public health threat, particularly in low and middle income countries where fragmented regulatory frameworks foster inappropriate practices and therapeutic failures. This study was conducted in Kinshasa, Democratic Republic of Congo, to examine access to and use of antibiotics in pig and poultry farming, and to analyze stakeholder perceptions of their roles and responsibilities in AMR governance. Data were collected through 149 in depth interviews and six focus groups involving medical doctors, veterinarians, paraprofessionals, farmers, drug sellers, laboratory technicians, regulatory agents, and technical partners. Respondents confirmed frequent use of antibiotics for prevention and treatment of infections, but also as growth promoters, notably colistin. Therapeutic failures were commonly reported, leading to empirical switching of antibiotics without susceptibility testing. Farmers mainly obtained antibiotics from veterinarians, while veterinarians themselves sometimes relied on human pharmacies due to limited availability of veterinary drugs. Medical doctors, in contrast, prescribed antibiotics exclusively through formal channels. Stakeholders emphasized weak veterinary services, lack of market control, and limited involvement of policymakers. Relational mapping revealed critical gaps in intersectoral information flows, highlighting the need for improved coordination. Overall, the findings suggest that combating AMR in pig and poultry farms in the city of Kinshasa requires an integrated One Health approach, including stronger governance of antibiotic supply chains, reduction of infectious pressure through prevention and biosecurity, improvement of therapeutic decision making, and institutionalization of coordination mechanisms.
- 29 June 2026
- Published by MDPI AG in Preprints.org
Open AccessMapping Antibiotic-Use Pathways and Leverage Points for AMR Control in Kinshasa’s Pig and Poultry Systems: A One Health Stakeholder Analysis
Antimicrobial resistance (AMR) is a major global public health threat, particularly in low and middle income countries where fragmented regulatory frameworks foster inappropriate practices and therapeutic failures. This study was conducted in Kinshasa, Democratic Republic of Congo, to examine access to and use of antibiotics in pig and poultry farming, and to analyze stakeholder perceptions of their roles and responsibilities in AMR governance. Data were collected through 149 in depth interviews and six focus groups involving medical doctors, veterinarians, paraprofessionals, farmers, drug sellers, laboratory technicians, regulatory agents, and technical partners. Respondents confirmed frequent use of antibiotics for prevention and treatment of infections, but also as growth promoters, notably colistin. Therapeutic failures were commonly reported, leading to empirical switching of antibiotics without susceptibility testing. Farmers mainly obtained antibiotics from veterinarians, while veterinarians themselves sometimes relied on human pharmacies due to limited availability of veterinary drugs. Medical doctors, in contrast, prescribed antibiotics exclusively through formal channels. Stakeholders emphasized weak veterinary services, lack of market control, and limited involvement of policymakers. Relational mapping revealed critical gaps in intersectoral information flows, highlighting the need for improved coordination. Overall, the findings suggest that combating AMR in pig and poultry farms in the city of Kinshasa requires an integrated One Health approach, including stronger governance of antibiotic supply chains, reduction of infectious pressure through prevention and biosecurity, improvement of therapeutic decision making, and institutionalization of coordination mechanisms.
- Open Access
- 3 January 2024
- Vol. 2 (1)
Performance of Chromogenic Candida Lab-Agar® Medium in Presumptive Identification of Candida Species from Clinical Samples at Sourô Sanou University Hospital of Bobo-Dioulasso, Burkina Faso
Introduction: The incidence of Candida infections is increasing worldwide. In clinical laboratories of resource-constrained countries, Candida speciation is commonly limited to germ tube tests and culture onto a chromogenic medium. In this study, we evaluated the diagnostic performance of Chromogenic Candida Lab-Agar® (CCL) in identifying Candida species from clinical samples. Methods: We evaluated the diagnostic performance of CCL with 83 yeast isolates collected from 73 clinical samples at the laboratory department of Sourô Sanou University Hospital of Bobo-Dioulasso, Burkina Faso. Clinical specimens included vaginal swabs, urine, and blood cultures. After preliminary isolation on Sabouraud chloramphenicol agar, yeast isolates were inoculated onto the CCL medium and incubated at 35 °C for 48 h. Matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS) and ribosomal DNA internal transcribed spacer (ITS) sequencing were used as reference methods. Results: Among yeast species, Candida albicans was the most prevalent (43.4%), followed by C. krusei (13.3%), C. glabrata (12.0%), C. kefyr (8.4%), and C. tropicalis (7.2%). The overall agreement rate of CCL was 56.6% and varied across Candida species; it was 94.4% for C. albicans, 50% for C. glabrata, 18.2% for C. krusei, and 33.3% for C. tropicalis. Conclusions: This study showed that CCL had moderate accuracy in identifying Candida at the species level from clinical specimens in a routine laboratory in Burkina Faso. The misidentification of non-albicans species may expose patients to inadequate antifungal treatment. Therefore, identifying yeast in a routine based on CCL is not enough and should be associated with more accurate methods.
- 3 January 2024
- Vol. 2 (1)
Open AccessPerformance of Chromogenic Candida Lab-Agar® Medium in Presumptive Identification of Candida Species from Clinical Samples at Sourô Sanou University Hospital of Bobo-Dioulasso, Burkina Faso
Introduction: The incidence of Candida infections is increasing worldwide. In clinical laboratories of resource-constrained countries, Candida speciation is commonly limited to germ tube tests and culture onto a chromogenic medium. In this study, we evaluated the diagnostic performance of Chromogenic Candida Lab-Agar® (CCL) in identifying Candida species from clinical samples. Methods: We evaluated the diagnostic performance of CCL with 83 yeast isolates collected from 73 clinical samples at the laboratory department of Sourô Sanou University Hospital of Bobo-Dioulasso, Burkina Faso. Clinical specimens included vaginal swabs, urine, and blood cultures. After preliminary isolation on Sabouraud chloramphenicol agar, yeast isolates were inoculated onto the CCL medium and incubated at 35 °C for 48 h. Matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS) and ribosomal DNA internal transcribed spacer (ITS) sequencing were used as reference methods. Results: Among yeast species, Candida albicans was the most prevalent (43.4%), followed by C. krusei (13.3%), C. glabrata (12.0%), C. kefyr (8.4%), and C. tropicalis (7.2%). The overall agreement rate of CCL was 56.6% and varied across Candida species; it was 94.4% for C. albicans, 50% for C. glabrata, 18.2% for C. krusei, and 33.3% for C. tropicalis. Conclusions: This study showed that CCL had moderate accuracy in identifying Candida at the species level from clinical specimens in a routine laboratory in Burkina Faso. The misidentification of non-albicans species may expose patients to inadequate antifungal treatment. Therefore, identifying yeast in a routine based on CCL is not enough and should be associated with more accurate methods.
- Open Access
- 25 February 2021
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 18 (5) , 2250
First Investigative Study of Azole-Resistant Aspergillus fumigatus in the Environment in Burkina Faso
Azole-resistant Aspergillus fumigatus (ARAF) strains have been reported on all continents, however, limited data exist on these strains in Africa, while several factors, mainly environmental ones, suggest their presence on this continent. This study aimed to assess the environmental prevalence of ARAF strains in Burkina Faso, a country situated in the West African region where data on ARAF is non-existent. In total, 120 environmental samples (soil) were collected and analyzed. Samples were screened for resistance using three azole-containing agar plates; one without azole antifungal (growth control) and two supplemented with either itraconazole (4 mg/L) or voriconazole (2 mg/L). The EUCAST susceptibility testing method was used to confirm the azole-resistant phenotype of A. fumigatus sensu-stricto isolates. Mutations in the cyp51A gene were determined by sequencing. Of the 120 samples, 51 positive samples showed growth of A. fumigatus isolates on control medium. One ARAF (2%; 1/51) isolate was found amongst A. fumigatus positive samples and harbored the F46Y/M172V/E427K cyp51A mutations. No TR34/L98H or TR46/Y121F/T289A mutations were observed. Our study described the first A. fumigatus isolate resistant to an azole antifungal in Burkina Faso.
- 25 February 2021
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 18 (5) , 2250
Open AccessFirst Investigative Study of Azole-Resistant Aspergillus fumigatus in the Environment in Burkina Faso
Azole-resistant Aspergillus fumigatus (ARAF) strains have been reported on all continents, however, limited data exist on these strains in Africa, while several factors, mainly environmental ones, suggest their presence on this continent. This study aimed to assess the environmental prevalence of ARAF strains in Burkina Faso, a country situated in the West African region where data on ARAF is non-existent. In total, 120 environmental samples (soil) were collected and analyzed. Samples were screened for resistance using three azole-containing agar plates; one without azole antifungal (growth control) and two supplemented with either itraconazole (4 mg/L) or voriconazole (2 mg/L). The EUCAST susceptibility testing method was used to confirm the azole-resistant phenotype of A. fumigatus sensu-stricto isolates. Mutations in the cyp51A gene were determined by sequencing. Of the 120 samples, 51 positive samples showed growth of A. fumigatus isolates on control medium. One ARAF (2%; 1/51) isolate was found amongst A. fumigatus positive samples and harbored the F46Y/M172V/E427K cyp51A mutations. No TR34/L98H or TR46/Y121F/T289A mutations were observed. Our study described the first A. fumigatus isolate resistant to an azole antifungal in Burkina Faso.
- Open Access
- 6 June 2017
- Published by MDPI AG in Antibiotics
- Vol. 6 (2) , 12
Bacteria from Animals as a Pool of Antimicrobial Resistance Genes
Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world.
- 6 June 2017
- Published by MDPI AG in Antibiotics
- Vol. 6 (2) , 12
Open AccessBacteria from Animals as a Pool of Antimicrobial Resistance Genes
Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world.
- Open Access
- 1 February 2017
- Published by Elsevier in The Lancet Infectious Diseases
- Vol. 17 (2) , 124-125
Route of transmission of Staphylococcus aureus
- 1 February 2017
- Published by Elsevier in The Lancet Infectious Diseases
- Vol. 17 (2) , 124-125
Open AccessRoute of transmission of Staphylococcus aureus
Biofilm formation of ica operon‐positive Staphylococcus epidermidis from different sources
Information on the prevalence of biofilm‐related factors (PIA, Bhp, Aap, Embp) in Staphylococcus epidermidis of animal origin is scarce. In this study, 263 S. epidermidis isolates of diverse origin (animal, farmers, patients, and laboratory staff) were investigated for the presence of the ica operon (icaRADBC). The icaRADBC‐positive isolates were further characterized by means of biofilm formation, presence of other biofilm‐related genes, antimicrobial resistance, and population structure. Of all isolates, 28.5% (n = 75) were icaRADBC‐positive, including 16.5% of animal origin, 29.1% farmer isolates, and 44.6% hospital‐associated isolates (including patients and laboratory staff isolates). Most icaRADBC‐positive isolates carried embp (n = 73), aap (n = 57), bhp (n = 22), and IS256 (n = 29). Statistical differences were found between animal and patient isolates for the presence of icaRADBC, bhp, and aap. No statistically significant relation was found between the presence of one or more genes and the level of biofilm formation. Most icaRADBC‐positive isolates belonged to the clonal complex 5 (formerly 2) and most sequence types corresponded to types previously observed in community and nosocomial S. epidermidis populations. Although the prevalence of S. epidermidis in the nasal cavity of bovines and poultry is low, some isolates belong to STs related to ica‐positive clinical strains.
Biofilm formation of ica operon‐positive Staphylococcus epidermidis from different sources
Information on the prevalence of biofilm‐related factors (PIA, Bhp, Aap, Embp) in Staphylococcus epidermidis of animal origin is scarce. In this study, 263 S. epidermidis isolates of diverse origin (animal, farmers, patients, and laboratory staff) were investigated for the presence of the ica operon (icaRADBC). The icaRADBC‐positive isolates were further characterized by means of biofilm formation, presence of other biofilm‐related genes, antimicrobial resistance, and population structure. Of all isolates, 28.5% (n = 75) were icaRADBC‐positive, including 16.5% of animal origin, 29.1% farmer isolates, and 44.6% hospital‐associated isolates (including patients and laboratory staff isolates). Most icaRADBC‐positive isolates carried embp (n = 73), aap (n = 57), bhp (n = 22), and IS256 (n = 29). Statistical differences were found between animal and patient isolates for the presence of icaRADBC, bhp, and aap. No statistically significant relation was found between the presence of one or more genes and the level of biofilm formation. Most icaRADBC‐positive isolates belonged to the clonal complex 5 (formerly 2) and most sequence types corresponded to types previously observed in community and nosocomial S. epidermidis populations. Although the prevalence of S. epidermidis in the nasal cavity of bovines and poultry is low, some isolates belong to STs related to ica‐positive clinical strains.
- 1 September 2014
- Published by Elsevier in Journal of Global Antimicrobial Resistance
- Vol. 2 (3) , 155-161
Antimicrobial susceptibility among Gram-positive and Gram-negative isolates collected in Europe between 2004 and 2010
- 1 September 2014
- Published by Elsevier in Journal of Global Antimicrobial Resistance
- Vol. 2 (3) , 155-161
Antimicrobial susceptibility among Gram-positive and Gram-negative isolates collected in Europe between 2004 and 2010
- Open Access
- 1 January 2014
- Published by Springer Nature in Annals of Clinical Microbiology and Antimicrobials
- Vol. 13 (1) , 20
Genetic characteristics and antimicrobial resistance of Staphylococcus epidermidis isolates from patients with catheter-related bloodstream infections and from colonized healthcare workers in a Belgian hospital
Staphylococcus epidermidis is a pathogen that is frequently encountered in the hospital environment. Healthcare workers (HCWs) can serve as a reservoir for the transmission of S. epidermidis to patients.
- 1 January 2014
- Published by Springer Nature in Annals of Clinical Microbiology and Antimicrobials
- Vol. 13 (1) , 20
Open AccessGenetic characteristics and antimicrobial resistance of Staphylococcus epidermidis isolates from patients with catheter-related bloodstream infections and from colonized healthcare workers in a Belgian hospital
Staphylococcus epidermidis is a pathogen that is frequently encountered in the hospital environment. Healthcare workers (HCWs) can serve as a reservoir for the transmission of S. epidermidis to patients.