Bacterial quorum sensing (QS) system regulates pathogenesis, virulence, and biofilm formation, and together they contribute to nosocomial infections. Opportunistic pathogens, such as Pseudomonas aeruginosa, rely on QS for regulating virulence factors. Therefore, blocking the QS system may aid management of various infectious diseases caused by human pathogens. Plant secondary metabolites can thwart bacterial colonization and virulence. As such, this study was undertaken to evaluate three extracts from the medicinal plant, Melianthus comosus, from which phytochemical compounds were identified with potential to inhibit QS-dependent virulence factors in P. aeruginosa. Chemical profiling of the three extracts identified 1,2-benzene dicarboxylic acid, diethyl ester, neophytadiene and hexadecanoic acid as the common compounds. Validation of antibacterial activity confirmed the same MIC values of 0.78 mg/mL for aqueous, methanol and dichloromethane extracts while selected guanosine showed MIC 0.031 mg/mL. Molecular docking analysis showed anti-quorum sensing (AQS) potential of guanosine binding to CviR’ and 2UV0 proteins with varying docking scores of −5.969 and −8.376 kcal/mol, respectively. Guanosine inhibited biofilm cell attachment and biofilm development at 78.88% and 34.85%, respectively. Significant swimming and swarming motility restriction of P. aeruginosa were observed at the highest concentration of plant extracts and guanosine. Overall, guanosine revealed the best swarming motility restrictions. M. comosus extracts and guanosine have shown clear antibacterial effects and subsequent reduction of QS-dependent virulence activities against P.aeruginosa. Therefore, they could be ideal candidates in the search for antipathogenic drugs to combat P.aeruginosa infections.

The ability of Klebsiella pneumoniae to form biofilm renders the pathogen recalcitrant to various antibiotics. The difficulty in managing K. pneumoniae related chronic infections is due to its biofilm-forming ability and associated virulence factors, necessitating the development of efficient strategies to control virulence factors. This study aimed at evaluating the inhibitory potential of selected phytochemical compounds on biofilm-associated virulence factors in K. pneumoniae, as well as authenticating their antibiofilm activity. Five phytochemical compounds (alpha-terpinene, camphene, fisetin, glycitein and phytol) were evaluated for their antibacterial and anti-biofilm-associated virulence factors such as exopolysaccharides, curli fibers, and hypermucoviscosity against carbapenem-resistant and extended-spectrum beta-lactamase-positive K. pneumoniae strains. The antibiofilm potential of these compounds was evaluated at initial cell attachment, microcolony formation and mature biofilm formation, then validated by in situ visualization using scanning electron microscopy (SEM). Exopolysaccharide surface topography was characterized using atomic force microscopy (AFM). The antibacterial activity of the compounds confirmed fisetin as the best carbapenem-resistant K. pneumoniae, demonstrating a minimum inhibitory concentration (MIC) value of 0.0625 mg/mL. Phytol, glycitein and α-terpinene showed MIC values of 0.125 mg/mL for both strains. The assessment of the compounds for anti-virulence activity (exopolysaccharide reduction) revealed an up to 65.91% reduction in phytol and camphene. Atomic force microscopy detected marked differences between the topographies of untreated and treated (camphene and phytol) exopolysaccharides. Curli expression was inhibited at both 0.5 and 1.0 mg/mL by phytol, glycitein, fisetin and quercetin. The hypermucoviscosity was reduced by phytol, glycitein, and fisetin to the shortest mucoid string (1 mm) at 1 mg/mL. Phytol showed the highest antiadhesion activity against carbapenem-resistant and extended-spectrum beta-lactamase-positive K. pneumoniae (54.71% and 50.05%), respectively. Scanning electron microscopy correlated the in vitro findings, with phytol significantly altering the biofilm architecture. Phytol has antibiofilm and antivirulence potential against the highly virulent K. pneumoniae strains, revealing it as a potential lead compound for the management of K. pneumoniae-associated infections.

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Background: Carbapenems are the most effective and important therapeutic options to serious infections caused by Enterobacteriaceae and Pseudomonas aeruginosa isolates. However, Carbepenems resistant isolates of Enterobacteriaceae and Pseudomonas aeroginosa are increasing worldwide. This study, therefore, was carried out to determine the resistance pattern of clinical isolates of Pseudomonas aeruginosa and Escherichia coli to Carbapenems. Methods: Fifty (50) E. coli and forty seven (47) Pseudomonas aeruginosa isolates were studied. Antibiotic Susceptibility test was performed as recommended by the CLSI. The antibiotics used were Ertapenem, Imipenem, Colistin Sulphate, Levofloxacin, and Piperacillin/Tazobactam. Results: Out of 97 clinical isolates subjected to drug susceptibilities test, Pseudomonas aeruginosa showed resistance to Ertapenem (87.2%); followed by Levofloxacin (19.1%), Colistin sulphate (12.8%), Piperacillin/tazobactan (4.3%) and Imipenem (2.1%) while E.coli displayed resistance to Ertapenem (30%), Levofloxacin (20%) and Colistin sulphate (4%). Interestingly, E coli was susceptible to Imipenem (0%) and Piperacillin/tazobactan (0%). A significant effect of Ertapenem on Pseudomonas aeruginosa was recorded. Also a significant effect of Piperacillin/Tazobactam was recorded on E coli. No significant effect was recorded among the other antibiotics on P aeruginosa or E coli. Conclusion: There is a high level of Carbapenems resistance among the clinical isolates of Pseudomonas aeruginosa compared to Escherichia coli in this study. Considering the therapeutic value of Carbapenems as one of the last options for the treatment of Enterobacteriaceae and Pseudomonas aeruginosa infections, rational Carbapenems usage is essential to reduce selective pressure over Enterobacteriaceae and Pseudomonas aeruginosa clinical isolates. Correspondance: O.A Ajibade. Adeleke University, P.M.B 250 Ede, Osun State E -Mail: oluwatosin.ajibade@adelekeuniversity.edu.ng RÉSUMÉ Contexte : Carbapénèmes sont les plus efficaces et les options thérapeutiques importants d'infections graves causées par les entérobactéries et Pseudomonas aeruginosa isolats. Cependant, Carbepenems isolats résistants d'entérobactéries et Pseudomonas aeroginosa sont en augmentation dans le monde entier. En conclusion, cette étude a été réalisée pour déterminer le profil de résistance des isolats cliniques de Pseudomonas aeruginosa et Escherichia coli de carbapénèmes.

Klebsiella pneumoniae is a pathogen of the Enterobacteriaceae family that causes healthcare-associated infections and has recently emerged as one of the most antibiotic-resistant organisms responsible for outbreaks in both community and healthcare settings. The aim of this study is to determine the resistance pattern of Klebsiella pneumoniae isolated from selected tertiary hospitals in Osun state, Nigeria. A total of 62 Klebsiella pneumoniae isolates were obtained from 1056 samples of urine, wound swab, ear swab, eye swab and other collection sites that were routinely submitted to the diagnostic laboratories of the selected tertiaryhospitals. Susceptibility to twelve (12) antibiotics (Oxoid) was determined using the Kirby Bauer disk diffusion method for the 62 isolates. Rate of resistance to carbapenems, fluoroquinolones, polymyxins, monobactams, cephalosporins, penicillin and phosphonic acid derivative are 29.03%, 47.84%, 29.03%, 46.77%, 50.80%, 93.55%, and 37.10% respectively. The isolates were mostly susceptible to carbapenems, especially, Imipenem with 74.19%. Highest resistance was to Penicillin (93.55%). The multiple antibiotic resistance (MAR) index revealed that 52 (83.87%) out of 62 isolates were multi-drug resistant. Increase in antibiotic resistance continues to be a problem amidst patients infected with Klebsiella pneumoniae which can be most likely attributed to increase in antibiotic misapplication, misuse and abuse which is most prevalent among youths. It is therefore of utmost importance that consistent monitoring of antibiotic resistance be done as it will assist in the appropriate selection of empiric antibiotic treatment in the proper setting.