Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) poses a significant public health concern due to its widespread prevalence and resistance to multiple antibiotics. This study aimed to assess the prevalence, resistance profile, and carriage of ESBL-encoding genes in ESBL-Ec isolates from broilers in two markets of Dakar, Senegal. Sampling over a one-year period revealed that 61.7% of broilers carried ESBL-Ec in their cecum. Antibiotic susceptibility testing of 186 ESBL-Ec isolates showed high resistance to β-lactam antibiotics, including ampicillin, ticarcillin, and third-generation cephalosporins. Notably, all isolates were susceptible to imipenem. Multidrug resistance was frequent, with 91.4% of the isolates displaying this phenotype. Comparison between the two markets revealed variations in resistance to quinolones. PCR analysis detected bla_CTX-M genes in all isolates, with bla_CTX-M-1 being the most prevalent subgroup. Additionally, bla_TEM and bla_OXA genes were found in 26.3% and 2.7% of isolates, respectively, while no bla_SHV genes were detected. Combinations of ESBL genes were common, with bla_CTX-M15-bla_TEM being the most frequent. These findings highlight the widespread prevalence of ESBL-Ec in broilers from Dakar markets, indicating a potential risk of transmission to humans through the food chain. Effective surveillance and intervention strategies are crucial to mitigate the spread of antimicrobial resistance in humans and animals.

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical antimicrobial resistance threat and a WHO-prioritized pathogen. With intrinsic resistance to multiple antibiotics and the emergence of pan-resistant isolates, CRAB infections are challenging to treat, often relying on polymyxins, tigecycline, aminoglycosides, or combinations, though co-resistance is rising globally. Phage therapy is considered as a potential treatment for multidrug-resistant A. baumannii. This study focused on isolating and characterizing phages active against CRAB strains from healthcare-associated infections in Dakar, Senegal. A lytic phage, Acinetobacter vAbaIN10, was isolated from wastewater collected at the Aristide Le Dantec Hospital in Dakar, Senegal. Isolation, host range, efficiency of plating, temperature and pH stability, lysis kinetics, one-step growth test, sequencing, and genomic analysis were performed. Phage vAbaIN10 belongs to the class Caudoviricetes and the genus Friunavirus. Its genome is 40,279 bp in size. Phage vAbaIN10 is stable across a wide pH range (3-9) and temperature range (25°C-60°C). The phage's lytic activity was evaluated at different multiplicities of infection (MOI): MOI 10, 1, and 10⁻¹. All MOIs significantly reduced the growth of host bacteria. The one-step growth curve showed that vAbaIN10 had a latency period of 25 min and a burst size of approximately 4.78 × 10³ phages per infected bacterial cell. No tRNA, mtRNA, clustered regularly interspaced short palindromic repeat, virulence factors, or antibiotic resistance genes were found in the genome. The biological and genomic characteristics of vAbaIN10 meet the requirements for its potential use in phage therapy.

Acinetobacter baumannii is a gram-negative, opportunistic pathogen, that is responsible for a wide variety of infections and is a significant cause of hospital-acquired infections. A. baumannii is listed by the World Health Organization (WHO) as a critical priority pathogen because of its high level of antibiotic resistance and the urgent need for alternative treatment solutions. To address this challenge, bacteriophages have been used to combat bacterial infections for more than a century, and phage research has regained interest in recent years due to antimicrobial resistance (AMR). However, although the vast majority of deaths from the AMR crisis will occur in developing countries in Africa and Asia, few phages’ studies have been conducted in these regions. In this study, we present a comprehensive characterization of the bacteriophages vAbBal23 and vAbAbd25, actives against extremely drug-resistant (XDR) A. baumannii. Phages were isolated from environmental wastewaters in Dakar, Senegal. The host-range, thermal and pH stabilities, infection kinetics, one step growth assay, antibiofilm activity assay, sequencing, and genomic analysis, were performed to characterize the isolated phages. Comparative genomic and phylogenetic analyses revealed that vAbBal23 and vAbAbd25 belong to the Caudoviricetes class, Autographiviridae family and Friunavirus genus. Both phages demonstrated activity against strains with capsular type KL230. They were stable over a wide pH range (pH 3 to 9) and at temperatures ranging from 25 °C to 40 °C. Additionally, the phages exhibited notable activity against both planktonic and biofilm cells of targeted extremely drug resistant A. baumannii. The results presented here indicate the lytic nature of vAbBal23 and vAbAbd25. This is further supported by the absence of genes encoding toxins, resistance genes and bacterial virulence factors, highlighting their potential for future phage applications. Phages vAbBal23 and vAbAbd25 are promising biological agents that can infect A. baumannii, making them suitable candidates for use in phage therapies.

Klebsiella pneumoniae, a common gut colonizer, has become a major opportunistic pathogen, especially with the rise of multidrug-resistant (MDR) strains. This study aimed to characterize two lytic bacteriophages against MDR K. pneumoniae strains isolated from hospital associated infections in Senegal. Among 28 MDR K. pneumoniae strains tested, phage vKpIN31 effectively lyse 15 strains encompassing 12 distinct K locus types. While phage vKpIN32 lysed 12 strains with 9 different K locus types, demonstrating broad host range activity. The isolated phages exhibited thermal and pH stability. One-step growth analysis revealed a latent period of 25 and 20 min and burst sizes of 281 and 246 PFU/cell for vKpIN31 and vKpIN32 respectively. The in vitro lytic activity of phages vKpIN31 and vKpIN32 at different multiplicity of infection (1, 10⁻¹, and 10⁻³) revealed variable lysis efficacy against three K. pneumoniae strains (KP6, KP7, and KP17), with the highest effectiveness observed at an MOI of 10⁻³ for both phages. Combination of both phages as cocktail led to improved efficacy against the targeted strains Also, both phages significantly reduced biofilm levels, from 18.6% to 67.9% for 24-hour mature biofilms and from 18.1% to 58.7% for 48-hour mature biofilms. Genomic analysis identified both phages as linear dsDNA viruses belonging to the Caudoviricetes class, and Sugarlandvirus sugarland species. No genes associated with a temperate life cycle, integrases, transposable elements, antibiotic resistance, or bacterial virulence were detected in their genomes. These findings highlight vKpIN31 and vKpIN32 as promising candidates for phage therapy. Additionally, their potential extends to serving as sources for antibacterial and antibiofilm agents, signifying their clinical relevance and therapeutic potential.

Two bacteriophages (phages) of Klebsiella pneumoniae were isolated from sewage water collected from Dakar, Senegal. Phage vKpIN17 belongs to the Przondovirus genus within the Autographiviridae family, with double-stranded DNA genomes, whereas vKpIN18 belongs to the Webervirus genus of the Drexlerviridae family.

Carbapenem resistant Acinetobacter baumannii (CRAB) is considered a top priority pathogen by the World Health Organization and is also considered a leading cause of healthcare-associated infections (HAIs). This study aimed to investigate antimicrobial resistance (AMR) patterns and perform comprehensive whole-genome analysis on CRAB strains isolated from HAIs in Dakar, Senegal. CRAB isolates were collected from 2018 to 2021 in two major hospitals in Dakar and subjected to antimicrobial susceptibility tests followed by whole genome sequencing and comprehensive bioinformatic analysis to identify resistance genes, mobile genetic elements (MGEs) and perform phylogeny analysis. The isolates demonstrated an alarming level of resistance to multiple classes of antibiotics, categorizing them as extremely drug resistant. Genetically, they present 5 distinct sequence types (ST1, ST52, ST85, ST107, and ST164), and an average of 71.9% accessory genes. They also present 30 to 51 genes associated with resistance to numerous classes of antibiotics. These genes included those responsible for resistance to β-lactams (such as bla_OXA-23, bla_NDM-1, bla_OXA-51 and bla_CTX-M15), to aminoglycosides (ant(3″)-IIa, aph(3″)-Ib, aph(3′)-Ia), to fluoroquinolones (such as qnrS1, qnrB17, AdeFGH efflux pump), to fosfomycin (fos2A, fosA6, AbaF), and to tetracyclines (tet(A), tet(B), tet(39)). This pioneering study offers insight into the molecular mechanisms underlying carbapenem-resistant bacteria associated with HAIs in Senegal. These findings emphasize the critical need to implement surveillance programs particularly for carbapenem-resistant bacteria to gain a comprehensive understanding of their prevalence, propagation, impact on patient health outcomes, and prolonged hospital stays.