Caffeic Acid Phosphanium Derivatives: Potential Selective Antitumor, Antimicrobial and Antiprotozoal Agents.

Caffeic acid (CA) is one of the most abundant natural compounds present in plants and has a broad spectrum of beneficial pharmacological activities. However, in some cases, synthetic derivation of original molecules can expand their scope. This study focuses on the synthesis of caffeic acid phosphanium derivatives with the ambition of increasing their biological activities. Four caffeic acid phosphanium salts (CAPs) were synthesized and tested for their cytotoxic, antibacterial, antifungal, and amoebicidal activity in vitro, with the aim of identifying the best area for their medicinal use. CAPs exhibited significantly stronger cytotoxic activity against tested cell lines (HeLa, HCT116, MDA-MB-231 MCF-7, A2058, PANC-1, Jurkat) in comparison to caffeic acid. Focusing on Jurkat cells (human leukemic T cell lymphoma), the IC50 value of CAPs ranged from 0.9 to 8.5 µM while IC50 of CA was >300 µM. Antimicrobial testing also confirmed significantly higher activity of CAPs against selected microbes in comparison to CA, especially for Gram-positive bacteria (MIC 13-57 µM) and the yeast Candida albicans (MIC 13-57 µM). The anti-Acanthamoeba activity was studied against two pathogenic Acanthamoeba strains. In the case of A. lugdunensis, all CAPs revealed a stronger inhibitory effect (EC50 74-3125 µM) than CA (>105 µM), while in A. quina strain, the higher inhibition was observed for three derivatives (EC50 44-291 µM). The newly synthesized quaternary phosphanium salts of caffeic acid exhibited selective antitumor action and appeared to be promising antimicrobial agents for topical application, as well as potential molecules for further research.

Carbapenem-Resistant Klebsiella pneumoniae in COVID-19 Era-Challenges and Solutions.

The COVID-19 era brought about new medical challenges, which, together with nosocomial bacterial infections, resulted in an enormous burden for the healthcare system. One of the most alarming nosocomial threats was carbapenem-resistant Klebsiella pneumoniae (CRKP). Monitoring CRKP incidence and antimicrobial resistance globally and locally is vitally important. In a retrospective study, the incidence of CRKP in the pre-COVID-19 period (2017-2019) and the COVID-19 pandemic (2020-2022) was investigated in the Central Military Hospital in Ruzomberok, Slovak Republic. The relative incidence of CRKP significantly increased during the COVID-19 period-by 4.8 times, from 0.18 to 0.76%. At the same time, 47% of CRKP-positive patients also had COVID-19. Twenty-six KPC and sixty-nine NDM-producing isolates were identified. CRKPs isolated in the year 2022 were submitted to whole genome sequencing, and their susceptibility was tested to cefiderocol, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam, with excellent results. KPC-producing isolates were also highly susceptible to colistin (92%). The NDM isolates revealed lower susceptibility rates, including only 57% colistin susceptibility. ST-307 prevailed in KPC and ST-11 in NDM isolates. Despite the excellent activity of new antimicrobials, rational antibiotic policy must be thoroughly followed, supported by complementary treatments and strict anti-epidemic precautions.

Susceptibility of Staphylococcus aureus strains to commercial therapeutic phage preparations.

OBJECTIVES: The aim of this study was to determine the susceptibility of Staphylococcus aureus strains to commercial phage preparations. The strains were isolated from clinical patients as well as from nasal mucosa of healthy carriers. BACKGROUND: The elevating number of antibiotic-resistant S. aureus strains present a therapeutic challenge, especially in high-risk patients. One of the promising ways to solve this problem is phage therapy. METHODS: Susceptibility of 111 carrier strains of S. aureus (4 strains were methicillin-resistant; MRSA) and 81 clinical isolates from bloodstream or skin and soft tissue infections (28 were MRSA) to four commercial phage preparations was assessed in vitro by spot assay. The clonality of S. aureus strains was determined by spa typing. RESULTS: Spa typing revealed 97 distinct spa types. A proportion of 73-80 % of the tested S. aureus strains were revealed to have in vitro phage susceptibility, depending on the clonal affiliation of the strains and phage preparation tested. The susceptibility to phage preparations was significantly higher in MRSA strains (p < 0.001). CONCLUSIONS: In vitro results indicate a promising therapeutic potential of the tested commercial anti-staphylococcal phage preparations. They could be applied to a broad spectrum of bacterial clones, and have an excellent activity especially against MRSA strains (Tab. 2, Fig. 2, Ref. 43).

Therapeutic Potential of Flavonoids and Tannins in Management of Oral Infectious Diseases-A Review.

Medicinal plants are rich sources of valuable molecules with various profitable biological effects, including antimicrobial activity. The advantages of herbal products are their effectiveness, relative safety based on research or extended traditional use, and accessibility without prescription. Extensive and irrational usage of antibiotics since their discovery in 1928 has led to the increasing expiration of their effectiveness due to antibacterial resistance. Now, medical research is facing a big and challenging mission to find effective and safe antimicrobial therapies to replace inactive drugs. Over the years, one of the research fields that remained the most available is the area of natural products: medicinal plants and their metabolites, which could serve as active substances to fight against microbes or be considered as models in drug design. This review presents selected flavonoids (such as apigenin, quercetin, kaempferol, kurarinone, and morin) and tannins (including oligomeric proanthocyanidins, gallotannins, ellagitannins, catechins, and epigallocatechin gallate), but also medicinal plants rich in these compounds as potential therapeutic agents in oral infectious diseases based on traditional usages such as Agrimonia eupatoria L., Hamamelis virginiana L., Matricaria chamomilla L., Vaccinium myrtillus L., Quercus robur L., Rosa gallica L., Rubus idaeus L., or Potentilla erecta (L.). Some of the presented compounds and extracts are already successfully used to maintain oral health, as the main or additive ingredient of toothpastes or mouthwashes. Others are promising for further research or future applications.

Antibacterial Activity of Medicinal Plants and Their Constituents in the Context of Skin and Wound Infections, Considering European Legislation and Folk Medicine-A Review.

Bacterial infections of skin and wounds may seriously decrease the quality of life and even cause death in some patients. One of the largest concerns in their treatment is the growing antimicrobial resistance of bacterial infectious agents and the spread of resistant strains not only in the hospitals but also in the community. This trend encourages researchers to seek for new effective and safe therapeutical agents. The pharmaceutical industry, focusing mainly on libraries of synthetic compounds as a drug discovery source, is often failing in the battle with bacteria. In contrast, many of the natural compounds, and/or the whole and complex plants extracts, are effective in this field, inactivating the resistant bacterial strains or decreasing their virulence. Natural products act comprehensively; many of them have not only antibacterial, but also anti-inflammatory effects and may support tissue regeneration and wound healing. The European legislative is in the field of natural products medicinal use formed by European Medicines Agency (EMA), based on the scientific work of its Committee on Herbal Medicinal Products (HMPC). HMPC establishes EU monographs covering the therapeutic uses and safe conditions for herbal substances and preparations, mostly based on folk medicine, but including data from scientific research. In this review, the medicinal plants and their active constituents recommended by EMA for skin disorders are discussed in terms of their antibacterial effect. The source of information about these plant products in the review is represented by research articles listed in scientific databases (Science Direct, PubMed, Scopus, Web of Science, etc.) published in recent years.

Characterization of Anti-Bacterial Effect of the Two New Phages against Uropathogenic Escherichia coli.

Urinary tract infections (UTIs) are among the events that most frequently need medical intervention. Uropathogenic Escherichia coli are frequently their causative agents and the infections are sometimes complicated by the presence of polyresistant nosocomial strains. Phage therapy is a tool that has good prospects for the treatment of these infections. In the present study, we isolated and characterized two bacteriophages with broad host specificity against a panel of local uropathogenic E. coli strains and combined them into a phage cocktail. According to genome sequencing, these phages were closely related and belonged to the Tequatrovirus genus. The newly isolated phages showed very good activity on a panel of local clinical E. coli strains from urinary tract infections. In the form of a two-phage cocktail, they were active on E. coli strains belonging to phylogroups B2 and D, with relatively lower activity in B1 and no response in phylogroup A. Our study is a preliminary step toward the establishment of a national phage bank containing local, well-characterized phages with therapeutic potential for patients in Slovakia.

Characterization of Clinical and Carrier Streptococcus agalactiae and Prophage Contribution to the Strain Variability.

Streptococcus agalactiae (group B Streptococcus, GBS) represents a leading cause of invasive bacterial infections in newborns and is also responsible for diseases in older and immunocompromised adults. Prophages represent an important factor contributing to the genome plasticity and evolution of new strains. In the present study, prophage content was analyzed in human GBS isolates. Thirty-seven prophages were identified in genomes of 20 representative sequenced strains. On the basis of the sequence comparison, we divided the prophages into eight groups named A-H. This division also corresponded to the clustering of phage integrase, even though several different integration sites were observed in some relative prophages. Next, PCR method was used for detection of the prophages in 123 GBS strains from adult hospitalized patients and from pregnancy screening. At least one prophage was present in 105 isolates (85%). The highest prevalence was observed for prophage group A (71%) and satellite prophage group B (62%). Other groups were detected infrequently (1-6%). Prophage distribution did not differ between clinical and screening strains, but it was unevenly distributed in MLST (multi locus sequence typing) sequence types. High content of full-length and satellite prophages detected in present study implies that prophages could be beneficial for the host bacterium and could contribute to evolution of more adapted strains.

Antimicrobial and Antioxidant Properties of Four Lycopus Taxa and an Interaction Study of Their Major Compounds.

The compositions of leaf infusions of three genotypes of Lycopus europaeus L. with origins in central Europe, namely L. europaeus A (LeuA), L. europaeus B (LeuB), and L. europaeus C (LeuC), and one genotype of L. exaltatus (Lex), were examined by LC-MS-DAD (Liquid Chromatography Mass Spectrometry and Diode Array Detection) analysis. This revealed the presence of thirteen compounds belonging to the groups of phenolic acids and flavonoids, with a predominance of rosmarinic acid (RA) and luteolin-7-O-glucuronide (LGlr). The antimicrobial activity of leaf infusions was tested on the collection strains of Gram-positive and Gram-negative bacteria, and on the clinical Staphylococcus aureus strains. We detected higher activity against Gram-positive bacteria, of which the most susceptible strains were those of Staphylococcus aureus, including methicillin-resistant and poly-resistant strains. Furthermore, we examined the antioxidant activity of leaf infusions using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods, and on NIH/3T3 cell lines using dichlorodihydrofluorescein diacetate (DCFH-DA). We also studied the mutual interactions between selected infusions, namely RA and/or LGlr. In the mixtures of leaf infusion and RA or LGlr, we observed slight synergism and a high dose reduction index in most cases. This leads to the beneficial dose reduction at a given antioxidant effect level in mixtures compared to the doses of the parts used alone. Therefore, our study draws attention to further applications of the Lycopus leaves as a valuable alternative source of natural antioxidants and as a promising topical antibacterial agent for medicinal use.

Derivatization of Rosmarinic Acid Enhances its in vitro Antitumor, Antimicrobial and Antiprotozoal Properties.

On its own, rosmarinic acid possesses multiple biological activities such as anti-inflammatory, antimicrobial, cardioprotective and antitumor properties, and these are the consequence of its ROS scavenging and inhibitory effect on inflammation. In this study, two quaternary phosphonium salts of rosmarinic acid were prepared for the purpose of increasing its penetration into biological systems with the aim of improving its antimicrobial, antifungal, antiprotozoal and antitumor activity. The synthetized molecules, the triphenylphosphonium and tricyclohexylphosphonium salts of rosmarinic acid, exhibited significantly stronger inhibitory effects on the growth of HCT116 cells with IC50 values of 7.28 or 8.13 µM in comparison to the initial substance, rosmarinic acid (>300 µM). For the synthesized derivatives, we detected a greater than three-fold increase of activity against Acanthamoeba quina, and a greater than eight-fold increase of activity against A. lugdunensis in comparison to rosmarinic acid. Furthermore, we recorded significantly higher antimicrobial activity of the synthetized derivatives when compared to rosmarinic acid itself. Both synthetized quaternary phosphonium salts of rosmarinic acid appear to be promising antitumor and antimicrobial agents, as well as impressive molecules for further research.

Characterisation of Cronobacter strains isolated from hospitalised adult patients.

Bacteria belonging to the genus Cronobacter are opportunistic pathogens known for causing rare but serious infections in neonates, including meningitis, necrotising enterocolitis and sepsis. Cronobacter infections occur also in adult populations, however, they generally have milder manifestations and their prevalence is uncertain. In this study, the presence of Cronobacter strains from adult patients in the University Hospital in Bratislava was investigated and overall 18 confirmed isolates from 321 patients (5.3%) were recovered. No Cronobacter positive sample was detected in 215 sputum samples from outpatients. The highest occurrence of Cronobacter strains was observed from stroke patients and this may be associated with an abnormal swallowing ability. The isolated strains belonged to the species Cronobacter sakazakii and Cronobacter malonaticus. In silico genotyping (MLST, CRISPR-cas array profiling) of whole genome sequences assigned the strains to three different MLST clones. The majority (12/18) of the isolated strains were sequence type ST513 or single locus variants ST514 and ST515, thereby being members of C. sakazakii pathovar clonal complex CC4. However, according to core genome MLST analysis the ST513-ST515 strains created a unique cluster substantially different from other CC4 strains. The isolated strains were susceptible to 18 tested antibiotics. All strains possess a genomic island encoding for increased thermal tolerance. As Cronobacter strains are frequently present in dried foods of plant origin, spread of a specific clone within a hospital may be caused by food transmission and may be facilitated by its tolerance to environmental stresses such as desiccation and temperature.

Antibiofilm Activity of Plant Polyphenols.

In the history of human medicine, antibiotics represent epochal examples of medical progress. However, with an approaching antibiotic crisis due to the emergence and extensive spread of antimicrobial resistance among bacterial agents, as well as to increasing number of patients with chronic and recalcitrant bacterial biofilm-associated infections, the naturally occurring molecules may become new sources of antibacterial and antibiofilm drugs for clinical usage. Polyphenols represent a class of plant natural products which are important in plant defense against microbial pathogens. The main focus of the review is on the antibiofilm activities of phenolic compounds against bacteria which play an essential role in medical device biofilm-associated infections. The other, not negligible part of the review is devoted to polyphenols' activity against bacterial agents that cause dental caries and periodontal disease.

Lycopus europaeus: phenolic fingerprint, antioxidant activity and antimicrobial effect on clinical Staphylococcus aureus strains.

Lycopus europaeus L. leaves water extract (LEL) was subjected to phytochemical analysis, and evaluated for its antibacterial and antioxidant effects. Antibacterial activity testing was performed on Staphylococcus aureus clinical strains from catheter-related and skin infections by broth microdilution test. LEL showed bactericidal activity at concentrations from 2500 to 5000 µg/mL against all, including methicillin resistant and polyresistant nosocomial, strains. Antioxidant activity was examined using DPPH and ABTS (11.3 and 9.8 µg/mL, respectively) and by ferric reducing ability of the plasma method (891 µmol AAE/g dry extract). Phytochemical analysis of LEL was performed by LC-DAD-MS/MS. Ten phenolic compounds were identified; two minor compounds (glucopyranosyl rosmarinic acid and sagerinig acid) have not been described in Lycopus yet. The major compounds, considered to be responsible for biological activities detected in the study, were determined as rosmarinic acid (76 mg/g) and luteolin-7-O-glucuronide (23 mg/g). L. europaeus arises from our study as a promising source of antibacterial agent for topical usage.

The Activity of Cotinus coggygria Scop. Leaves on Staphylococcus aureus Strains in Planktonic and Biofilm Growth Forms.

The purpose of this study was to detect the effectiveness of Cotinus coggygria Scop. leaves methanol extract against planktonic and biofilm growth forms of Staphylococcus aureus. The antimicrobial activity was determined by the broth microdilution test. Minimal inhibitory concentrations and minimal bactericidal concentrations were detected against two collection and ten clinical S. aureus strains. Anti-biofilm activity of the tested extract was detected using 24 h bacterial biofilm on the surface of microtiter plate wells. The biofilm inhibitory activity was evaluated visually after 24 h interaction of extract with biofilm, and the eradicating activity by a regrowth method. The tested extract showed bactericidal activity against all S. aureus strains (methicillin susceptible or methicillin resistant) in concentrations ranging from 0.313 to 0.625 mg·mL(-1). Biofilm inhibitory concentrations were 10-times higher and biofilm eradicating concentrations 100-times higher (8 and 32 mg·mL(-1), respectively). The phytochemical analysis of C. coggygria leaves 60% methanol extract performed by LC-DAD-MS/MS revealed quercetin rhamnoside, methyl gallate, and methyl trigallate as main constituents. Results of our study indicate that C. coggygria, rich in tannins and flavonoids, seems to be a prospective topical antibacterial agent with anti-biofilm activity.

In vitro efficacy of various topical antimicrobial agents in different time periods from contamination to application against 6 multidrug-resistant bacterial strains isolated from burn patients.

AIM: In vitro efficacy evaluation of eleven topical antimicrobials against multidrug-resistant (MDR) bacteria isolated from burn wounds of our patients. MATERIAL AND METHODS: Growth of six MDR bacterial strains: Pseudomonas aeruginosa (2 strains), Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis and Escherichia coli in burn-wound models was evaluated 24-h after application of the tested agents. Four different wound models were created to investigate the role of time elapsed between inoculation of bacteria and application of the agents on their antimicrobial activity and efficacy. RESULTS: The efficacy against all the 6 bacteria in freshly contaminated wounds was excellent in majority of the tested agents. The longer was the time interval between inoculation and application of the topical antimicrobial agents, the higher failure of the agents was observed. CONCLUSIONS: Topical antimicrobials play an important role in treatment of burn wounds, but they should be used according to their efficacy against bacterial strains present in patients' wounds. In cases where topical agents have been applied after 24 h, when formation of mature biofilm in the wound could be expected, it would probably not be possible to kill all the bacteria using topical antimicrobial therapy only.

Rosmarinic acid interaction with planktonic and biofilm Staphylococcus aureus.

The subject of study was the evaluation of antibacterial activities of rosmarinic acid (RA) on clinical Staphylococcus aureus strains obtained from catheter-related infections. Minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC) of RA were tested by broth microdilution assay. Biofilm-eradication activity was detected on 24-hour biofilm in microtiter plates using a regrowth technique; activity on biofilm formation was measured by a microtiter plate method after RA application to bacterial samples after 0, 1, 3 and 6 hours of biofilm development. RA had antimicrobial activity on all tested strains in concentrations from 625 to 1250 microg.mL-1 (MICs equal to MBCs). No biofilm-eradication activity on 24-hour biofilm was observed in the tested range of concentrations (from 156 to 5000 microg.mL-1). Subinhibitory RA concentrations suppressed the biofilm production, when applied at early stages of its development. Concentrations lower than subinhibitory stimulated the biofilm mass production in a concentration- and time-dependent manner. Considering our results, RA could be a candidate for a topical antimicrobial agent with killing activity on planktonic forms of bacteria and suppressing activity in the early stages of biofilm development, but probably not for the therapy of catheter-related infections as a sole agent.

Bactofection with toll-like receptor 4 in a murine model of urinary tract infection.

The role of innate immunity in the prevention of urinary tract infection is well-documented. Toll-like receptor 4 (TLR4) is a major determinant of innate immune response. In an animal model of urinary tract infection, bactofection-mediated gene transfer of TLR4 was tested in a preventive approach. Bactofection with TLR4 reduced the colonization with uropathogenic Escherichia coli by 91% in the kidney and by 41% in the bladder. Reduced colonization was associated with lower oxidative stress and expression of monocyte chemoattractant protein-1 and myeloperoxidase in the kidney. Bactofection with TLR4 was successful in the prevention of ascending pyelonephritis. Further studies should focus on long-term effects, the dose response and the potential therapeutic use in models of chronic urinary tract infection.

Antimicrobial activity of Mahonia aquifolium crude extract and its major isolated alkaloids.

The crude extract of Mahonia aquifolium (Pursh) Nutt. stem bark and its two main protoberberine alkaloids, berberine and jatrorrhizine, were tested for their in vitro antimicrobial activity. Twenty strains of coagulase-negative staphylococci and 20 strains of Propionibacterium acnes isolated from skin lesions of patients with a severe form of acne, and 20 strains of Candida sp. isolated from chronic vulvovaginal candidoses were tested for their susceptibility to crude extract and two isolated alkaloids. The minimum inhibitory concentrations obtained in this study illustrate the varying degrees of antibacterial and antifungal activity of the tested agents. The results indicate a rational basis for the traditional use of Mahonia aquifolium for localized skin and mucosal infection therapy, as well as for the possible development of a preparation for supportive therapy of the diseases mentioned above.