Efficacy of Acacia nilotica aqueous extract in treating biofilm-forming and multidrug resistant uropathogens isolated from patients with UTI syndrome

Plant-Origin Components: New Players to Combat Antibiotic Resistance in Klebsiella pneumoniae

Klebsiella pneumoniae (Kpn) is an opportunistic pathogen that causes intrahospital complications such as pneumonia, liver abscesses, soft tissue infections, urinary infections, bacteraemia, and, in some cases, death. Since this bacterium has a higher frequency than other Gram-negative pathogens, it has become an important pathogen to the health sector. The adaptative genome of Kpn likely facilitates increased survival of the pathogen in diverse situations. Therefore, several studies have been focused on developing new molecules, synergistic formulations, and biomaterials that make it possible to combat and control infections with and dispersion of this pathogen. Note that the uncontrolled antibiotic administration that occurred during the pandemic led to the emergence of new multidrug-resistant strains, and scientists were challenged to overcome them. This review aims to compile the latest information on Kpn that generates intrahospital infections, specifically their pathogenicity-associated factors. Furthermore, it explains the natural-product-based treatments (extracts and essential oils) developed for Kpn infection and dispersion control.

Evolving biofilm inhibition and eradication in clinical settings through plant-based antibiofilm agents

BACKGROUND

After almost 100 years since evidence of biofilm mode of growth and decades of intensive investigation about their formation, regulatory pathways and mechanisms of antimicrobial tolerance, nowadays there are still no therapeutic solutions to eradicate bacterial biofilms and their biomedical related issues.

PURPOSE

This review intends to provide a comprehensive summary of the recent and most relevant published studies on plant-based products, or their isolated compounds with antibiofilm activity mechanisms of action or identified molecular targets against bacterial biofilms. The objective is to offer a new perspective of most recent data for clinical researchers aiming to prevent or eliminate biofilm-associated infections caused by bacterial pathogens.

METHODS

The search was performed considering original research articles published on PubMed, Web of Science and Scopus from 2015 to April 2023, using keywords such as "antibiofilm", "antivirulence", "phytochemicals" and "plant extracts".

RESULTS

Over 180 articles were considered for this review with a focus on the priority human pathogens listed by World Health Organization, including Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Inhibition and detachment or dismantling of biofilms formed by these pathogens were found using plant-based extract/products or derivative compounds. Although combination of plant-based products and antibiotics were recorded and discussed, this topic is currently poorly explored and only for a reduced number of bacterial species.

CONCLUSIONS

This review clearly demonstrates that plant-based products or derivative compounds may be a promising therapeutic strategy to eliminate bacterial biofilms and their associated infections. After thoroughly reviewing the vast amount of research carried out over years, it was concluded that plant-based products are mostly able to prevent biofilm formation through inhibition of quorum sensing signals, but also to disrupt mature biofilms developed by multidrug resistant bacteria targeting the biofilm extracellular polymeric substance. Flavonoids and phenolic compounds seemed the most effective against bacterial biofilms.

Effects of Dietary Bioactive Lipid Compounds of Acacia nilotica Bark on Productive Performance, Antioxidant Status, and Antimicrobial Activities of Growing Rabbits under Hot Climatic Conditions

This study aimed to evaluate the efficacy of dietary Acacia nilotica bark bioactive lipid compounds (ANBBLCs) as novel feed additives on the growth performance, carcass criteria, antioxidants, and antimicrobial activities of growing male rabbits. A total of 100 California male weanling rabbits aged 35 days were divided into four nutritional treatments, each of which contained ANBBLCs at concentrations of 0 (control group), 50, 100, and 150 mg/kg diet (n = 25 per treatment, each replication consisting of one animal). The average body weight of the animals was 613 ± 14 g. The experiments lasted for 56 days. Dietary ANBBLC levels linearly improved (p < 0.05) the body weight, body weight gain, and feed conversion ratio (FCR) of rabbits. Furthermore, with increasing concentrations of ANBBLCs, the total antioxidant capacity of blood and liver tissue was linearly (p < 0.05) enhanced. Lactobacillus increased and Staphylococcus decreased (p < 0.05) in comparison to the control group when ANBBLC levels were added to the diets of rabbits. Rabbit diets supplemented with ANBBLCs increased dressing percentages and decreased abdominal fat. This study shows that ANBBLCs can be used as a feed additive to enhance the growth performance, carcass criteria, antioxidant, and antibacterial properties of growing rabbits.

Multidrug-Resistant Acinetobacter baumannii Infections in the United Kingdom versus Egypt: Trends and Potential Natural Products Solutions

Acinetobacter baumannii is a problematic pathogen of global concern. It causes multiple types of infection, especially among immunocompromised individuals in intensive care units. One of the most serious concerns related to this pathogen is its ability to become resistant to almost all the available antibiotics used in clinical practice. Moreover, it has a great tendency to spread this resistance at a very high rate, crossing borders and affecting healthcare settings across multiple economic levels. In this review, we trace back the reported incidences in the PubMed and the Web of Science databases of A. baumannii infections in both the United Kingdom and Egypt as two representative examples for countries of two different economic levels: high and low-middle income countries. Additionally, we compare the efforts made by researchers from both countries to find solutions to the lack of available treatments by looking into natural products reservoirs. A total of 113 studies reporting infection incidence were included, with most of them being conducted in Egypt, especially the recent ones. On the one hand, this pathogen was detected in the UK many years before it was reported in Egypt; on the other hand, the contribution of Egyptian researchers to identifying a solution using natural products is more notable than that of researchers in the UK. Tracing the prevalence of A. baumannii infections over the years showed that the infections are on the rise, especially in Egypt vs. the UK. Further concerns are linked to the spread of antibiotic resistance among the isolates collected from Egypt reaching very alarming levels. Studies conducted in the UK showed earlier inclusion of high-throughput technologies in the tracking and detection of A. baumannii and its resistance than those conducted in Egypt. Possible explanations for these variations are analyzed and discussed.

Fig latex inhibits the growth of pathogenic bacteria invading human diabetic wounds and accelerates wound closure in diabetic mice

Impaired wound healing is one of the most critical complications associated with diabetes mellitus. Infections and foot ulcers are major causes of morbidity for diabetic patients. The current treatment of diabetic foot ulcers, commonly used antibiotics, is associated with the development of bacterial resistance. Hence, novel and more effective natural therapeutic antibacterial agents are urgently needed and should be developed against the pathogenic bacteria inhabiting diabetic wounds. Therefore, the current study aimed to investigate the impact of fig latex on pathogenic bacteria and its ability to promote the healing process of diabetic wounds. The pathogenic bacteria were isolated from patients with diabetic foot ulcers admitted to Assiut University Hospital. Fig latex was collected from trees in the Assiut region, and its chemical composition was analyzed using GC‒MS. The antibacterial efficacy of fig latex was assessed on the isolated bacteria. An in vivo study to investigate the effect of fig latex on diabetic wound healing was performed using three mouse groups: nondiabetic control mice, diabetic mice and diabetic mice treated with fig latex. The influence of fig latex on the expression levels of β-defensin-1, PECAM-1, CCL2 and ZO-1 and collagen formation was investigated. The GC‒MS analysis demonstrated the presence of triterpenoids, comprising more than 90% of the total latex content. Furthermore, using a streptozotocin-induced diabetic mouse model, topical treatment of diabetic wound tissues with fig latex was shown to accelerate and improve wound closure by increasing the expression levels of β-defensin-1, collagen, and PECAM-1 compared to untreated diabetic wounds. Additionally, fig latex decreased the expression levels of ZO-1 and CCL2.

Synthesis of Cinnamum zeylanicum and Acacia nilotica Extracts and Their Antibacterial Activity against Staphylococcus aureus and Streptococcus pyogenes

Different plants are used medically and thofese therapeutic plants have great importance for healing contagious wounds. This herbal treatment is actually also a substitute of different antibiotics and having less side effects on intestinal systems of animals. The foremost concern of this study was to observe the antibacterial activity of Cinnamum zeylanicum and Acacia nilotica. Pathogenic bacteria obtained from wound samples and later identified by biochemical and molecular characterization. Methanol (an organic solvent) was used to extract Cinnamum zeylanicum and Acacia nilotica to check their antimicrobial exertion by using agar diffusion method. Different antibiotics such as, ampicillin, oflaxocin, ticarcillin and cefexime, showed their susceptibility toward antibiotics. The zone of inhibitions for antibiotic and plant extracts' antibacterial activity were measured. Pathogenic bacteria were identified as Staphylococcus aureus and Streptococcus pyogenesby molecular characterization. These bacteria showed susceptibility to antibiotics and also the plant extracts. Antibiotic oflaxocin showed maximum activity against these two pathogens (12.25 ± 0.44 and 12.375 ± 0.47) while antibiotic cefixime showed minimum effect (1.25 ± 0.28 and 0.625 ± 0.25). Plant extracts showed significant antibacterial activity with maximum activity (14 ± 0.9 by Acacia nilotica and 12 ± 0.5 by Cinnamum zeylanicum) in 100% solution. It can be concluded thatmethanolic extract of traditional therapeutic plants proved to be a promising source of antimicrobial agents against antibiotic resistant bacteria. Cinnamum zeylanicum and Acacia nilotica were observed to be competent as antibacterial tool against pathogenic bacterial strains.

Phylogenetic analysis and antimicrobial susceptibility profile of uropathogens

The uropathogens is the main cause of urinary tract infection (UTI). The aim of the study was to isolate bacteria from urine samples of UTI patients and find out the susceptibility of isolated bacteria. Bacteria were identified using both conventional and molecular methods. Sanger sequence procedure used for 16S ribosomal RNA and phylogenetic analysis was performed using Molecular Evolutionary Genetics Analysis (MEGA-7) software. In this study, Escherichia coli, Klebsiella pneumonia, Staphylococcus were reported as 58, 28 and 14.0% respectively. Phylogenetic tree revealed that 99% of sample No. Ai (05) is closely related to E. coli to (NR 114042.1 E. coli strain NBRC 102203). Aii (23) is 99% similar to K. pneumoniae to (NR 117686.1 K. pneumonia strain DSM 30104) and 90% Bi (48) is closely linked to S. aureus to (NR 113956.1 S. aureus strain NBRC 100910). The antibiotic susceptibility of E. coli recorded highest resistance towards ampicillin (90%) and least resistant to ofloxacin (14%). Some of the other antibiotics such amoxicillin, ciprofloxacin, gentamicin, ceftazidime, cefuroxime and nitrofurantoin resistance were observed 86, 62, 24, 55, 48 and 35% respectively. The cefuroxime showed the highest antibiotic resistance against K. pneumoniae with 85% followed by amoxicillin, ciprofloxacin, gentamicin, ceftazidime, ampicillin and nitrofurantoin resulted in 60, 45, 67, 70, 75 and 30% respectively. The resistance of S. aureus against erythromycin, cefuroxime and ampicillin were found with 72%. The resistance against amoxicillin, gentamicin, ceftazidime and ceftriaxone found 57, 43, 43 and 15% respectively. Phylogenetic analysis shows that sequences are closely related with the reference sequences and E. coli is the dominant bacteria among UTI patients and is resistant to the commercially available antibiotics.

Design, Synthesis and Evaluation of Novel Antimicrobial Polymers Based on the Inclusion of Polyethylene Glycol/TiO2 Nanocomposites in Cyclodextrin as Drug Carriers for Sulfaguanidine

Polymers and their composites have recently attracted attention in both pharmaceutical and biomedical applications. Polyethylene glycol (PEG) is a versatile polymer extensively used in medicine. Herein, three novel PEG-based polymers that are pseudopolyrotaxane (PEG/α-CD) (1), titania–nanocomposite (PEG/TiO₂NPs) (2), and pseudopolyrotaxane–titania–nanocomposite (PEG/α-CD/TiO₂NPs) (3), were synthesized and characterized. The chemical structure, surface morphology, and optical properties of the newly materials were examined by FT-IR, ¹H-NMR, SEM, and UV–Vis., respectively. The prepared polymers were used as drug carriers of sulfaguanidine as PEG/α-CD/Drug (4), PEG/TiO₂NPs/Drug (5), and PEG/α-CD/TiO₂NPs/Drug (6). The influence of these drug-carrying formulations on the physical and chemical characteristics of sulfaguanidine including pharmacokinetic response, solubility, and tissue penetration was explored. Evaluation of the antibacterial and antibiofilm effect of sulfaguanidine was tested before and after loading onto the prepared polymers against some Gram-negative and positive bacteria (E. coli, Pseudomonas aeruginosa, and Staphylococcus aureus (MRSA)), as well. The results of this work turned out to be very promising as they confirmed that loading sulfaguanidine to the newly designed polymers not only showed superior antibacterial and antibiofilm efficacy compared to the pure drug, but also modified the properties of the sulfaguanidine drug itself.

Antibacterial activity of medicinal plants against uropathogenic Escherichia coli

Urinary tract infections (UTIs) are one of the most common bacterial infections with uropathogenic Escherichia coli (UPEC) being the most prevalent causative agent in both complicated and uncomplicated UTIs. Antibiotic resistance among UPEC has been already demonstrated against a wide variety of antibiotics and the situation is continuing to deteriorate increasing the rate of recurrence and the difficulty of treatment and prophylaxis. Recently, a big attention has been paid to non-antibiotic approaches as an alternative to conventional antibiotics. Among many strategies, phytotherapy has gained a special attention worldwide. Herbal remedies have been used in traditional medicine since ancient times and they are well known for their effectiveness in treating many health conditions including UTIs. Researches are conducted continuously to validate the use of many medicinal plants against UPEC, investigate their mechanisms of action, and determine their active constituents. Our extensive review of the recent literature revealed that many phytochemicals are shown to target and inhibit a wide variety of bioprocesses in UPEC, such as adhesion, motility, biofilm formation, and quorum sensing. Such natural approaches are very promising in confronting the antibiotic resistance of UPEC and can be further used to develop plant-based strategies and pharmaceutical products to treat and prevent UTIs caused by UPEC.

Antibacterial, Antibiofilm, and Efflux Pump Inhibitory Properties of the Crude Extract and Fractions from Acacia macrostachya Stem Bark

Microbial infections remain a public health problem due to the upsurge of bacterial resistance. In this study, the antibacterial, antibiofilm, and efflux pump inhibitory activities of the stem bark of Acacia macrostachya, an indigenous African medicinal plant, were investigated. In traditional medicine, the plant is used in the treatment of microbial infections and inflammatory conditions. A crude methanol extract obtained by Soxhlet extraction was partitioned by column chromatography to obtain the petroleum ether, ethyl acetate, and methanol fractions. Antibacterial, efflux pump inhibition and antibiofilm formation activities were assessed by the high-throughput spot culture growth inhibition (HT-SPOTi), ethidium bromide accumulation, and the crystal violet retention assay, respectively. The minimum inhibitory concentrations (MICs) of the crude extract and major fractions ranged from 250 to ≥500 μg/mL. At a concentration of 3.9–250 μg/mL, all extracts demonstrated >80% inhibition of biofilm formation in S. aureus. In P. aeruginosa, the EtOAc fraction showed the highest antibiofilm activity (59–69%) while the pet-ether fraction was most active against E. coli biofilms (45–67%). Among the test samples, the crude extract, methanol, and ethyl acetate fractions showed remarkable efflux pump inhibition in S. aureus, E. coli, and P. aeruginosa. At ½ MIC, the methanol fraction demonstrated significant accumulation of EtBr in E. coli having superior efflux inhibition over the standard EPIs: chlorpromazine and verapamil. Tannins, flavonoids, triterpenoids, phytosterols, coumarins, and saponins were identified in preliminary phytochemical studies. Stigmasterol was identified in the EtOAc fraction. This study justifies the use of A. macrostachya in the treatment of infections in traditional medicine and highlights its potential as a source of bioactive compounds that could possibly interact with some resistance mechanisms in bacteria to combat antimicrobial resistance.

Syzygium aromaticum Extracts as a Potential Antibacterial Inhibitors against Clinical Isolates of Acinetobacter baumannii: An In-Silico-Supported In-Vitro Study

Imipenem is the most efficient antibiotic against Acinetobacter baumannii infection, but new research has shown that the organism has also developed resistance to this agent. A. baumannii isolates from a total of 110 clinical samples were identified by multiplex PCR. The antibacterial activity of Syzygium aromaticum multiple extracts was assessed following the GC-Mass spectra analysis. The molecular docking study was performed to investigate the binding mode of interactions of guanosine (Ethanolic extract compound) against Penicillin- binding proteins 1 and 3 of A. baumannii. Ten isolates of A. baumannii were confirmed to carry recA and iutA genes. Isolates were multidrug-resistant containing bla_TEM and Bla_SHV. The concentrations (0.04 to 0.125 mg mL^-1) of S. aromaticum ethanolic extract were very promising against A. baumannii isolates. Even though imipenem (0.02 mg mL^-1) individually showed a great bactericidal efficacy against all isolates, the in-silico study of guanosine, apioline, eugenol, and elemicin showed acceptable fitting to the binding site of the A. baumannii PBP1 and/or PBP3 with highest binding energy for guanosine between -7.1 and -8.1 kcal/mol respectively. Moreover, it formed π-stacked interactions with the residue ARG76 at 4.14 and 5.6, Å respectively. These findings might support the in vitro study and show a substantial increase in binding affinity and enhanced physicochemical characteristics compared to imipenem.

Efficacy of Ethanolic Extract of Syzygium aromaticum in the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Clinical Isolates Associated with Urinary Tract Infections

Pseudomonas aeruginosa is an organism commonly found in the environment and one of the most common causes of human urinary tract infections in developed and developing countries. The present study aimed to investigate the effect of five medicinal plant extracts on the isolated drug-resistant P. aeruginosa clinical isolates. A total of 100 urine samples were collected from Nagaa Hammadi and Qena General Hospitals and private medical analysis laboratories in Qena governorate, Upper Egypt. Samples were screened for the prevalence of UTI pathogens by biochemical tests, antibiotics sensitivity, detection of virulence, and antibiotic-resistant genes by using multiplex PCR. P. aeruginosa is by far the subdominant causative agent with a percentage of 14%. Clinical isolates were multidrug-resistant, containing bla TEM, bla SHV, toxA, lasB, pslA, and fliC resistant and virulence genes. Based on bioactivity, the ethanolic extract of clove (Syzygium aromaticum) was the most active extract among tested medicinal plants and had the maximum zone of inhibition sized 23 mm against tested bacteria. The results of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) showed a high decrease of inhibition within a concentration range of (10 to 121.25 mg/mL and 20 to 30 mg/mL, respectively). Further, major compounds of oleic acid (27.22%), guanosine (8.91%), indole (6.83%), 1-eicosene (6.30%), and cis-10-nonadecenoic acid (5.37%) were determined among 12 bioactive compounds in the ethanolic extract of S. aromaticum using gas chromatography-mass spectrometry (GC-MS). These results indicated that the ethanolic extract of S. aromaticum is a promising antibacterial agent for further studies aiming to control bacterial infections including MDR bacteria and develop novel therapeutic alternatives for the treatment of UTI.

Prevalence of lipase producer Aspergillus niger in nuts and anti-biofilm efficacy of its crude lipase against some human pathogenic bacteria

Nuts are the natural source of healthy lipids, proteins, and omega-3. They are susceptible to fungal and mycotoxins contamination because of their high nutritional value. Twenty-five species comprising 12 genera were isolated from 80 samples of dried fruits and nuts using the dilution plate method. Peanut recorded the highest level of contamination followed by coconut; almond and raisin were the lowest. Aspergillus was the most prevalent genus and A.niger, was the most dominant species. The morphological identification of the selected A.niger isolates as they were detected in high frequency of occurrence was confirmed by using 18SrRNA sequence. Ochratoxin biosynthesis gene Aopks was detected in the tested isolates. Lipase production by the selected A.niger isolates was determined with enzyme activity index (EAI) ranging from 2.02 to 3.28. A.niger-26 was the highest lipase producer with enzyme activity of 0.6 ± 0.1 U/ml by the trimetric method. Lip2 gene was also detected in the tested isolates. Finally, the antibacterial and antibiofilm efficiency of crude lipase against some human pathogens was monitored. Results exhibited great antibacterial efficacy with minimum bactericidal concentration (MBC) of 20 to 40 µl/100 µl against Escherichiacoli, Pseudomonasaeruginosa, Proteusmirabilis, and Methicillin-resistant Staphylococcusaureus (MRSA). Interestingly, significant anti-biofilm efficacy with inhibition percentages of 95.3, 74.9, 77.1 and 93.6% was observed against the tested pathogens, respectively.

Optimizing and purifying extracellular amylase from soil bacteria to inhibit clinical biofilm-forming bacteria

BACKGROUND

Bacterial biofilms have become a major threat to human health. The objective of this study was to isolate amylase-producing bacteria from soil to determine the overall inhibition of certain pathogenic bacterial biofilms.

METHODS

We used serial dilution and the streaking method to obtain a total of 75 positive amylase isolates. The starch-agar plate method was used to screen the amylolytic activities of these isolates, and we used morphological and biochemical methods to characterize the isolates. Optimal conditions for amylase production and purification using Sephadex G-200 and SDS-PAGE were monitored. We screened these isolates' antagonistic activities and the purified amylase against pathogenic and multi-drug-resistant human bacteria using the agar disk diffusion method. Some standard antibiotics were controlled according to their degree of sensitivity. Finally, we used spectrophotometric methods to screen the antibiofilm 24 and 48 h after application of filtering and purifying enzymes in order to determine its efficacy at human pathogenic bacteria.

RESULTS

The isolated Bacillus species were Bacillus megaterium (26.7%), Bacillus subtilis (16%), Bacillus cereus (13.3%), Bacillus thuringiesis (10.7%), Bacillus lentus (10.7%), Bacillus mycoides (5.3%), Bacillus alvei (5.3%), Bacillus polymyxa (4%), Bacillus circulans (4%), and Micrococcus roseus (4%). Interestingly, all isolates showed a high antagonism to target pathogens. B. alevi had the highest recorded activity (48 mm) and B. polymyxa had the lowest recorded activity (12 mm) against Staphylococcus aureus (MRSA) and Escherichia coli, respectively. On the other hand, we detected no antibacterial activity for purified amylase. The supernatant of the isolated amylase-producing bacteria and its purified amylase showed significant inhibition for biofilm: 93.7% and 78.8%, respectively. This suggests that supernatant and purified amylase may be effective for clinical and environmental biofilm control.

DISCUSSION

Our results showed that soil bacterial isolates such as Bacillus sp. supernatant and its purified amylase are good antibiofilm tools that can inhibit multidrug-resistant former strains. They could be beneficial for pharmaceutical use. While purified amylase was effective as an antibiofilm, the isolated supernatant showed better results.