Effects of Proanthocyanidins on Adhesion, Growth, and Virulence of Highly Virulent Extraintestinal Pathogenic Escherichia coli Argue for Its Use to Treat Oropharyngeal Colonization and Prevent Ventilator-Associated Pneumonia

Polyphenol Analysis and Antibacterial Potentials of Twig Extracts of Salix aurita, S. pyrolifolia, and S. caprea Growing Naturally in Finland

Salix species have been used in traditional medicine to treat fever and inflammation. However, there is no reported information on the antibacterial activities of S. aurita and S. pyrolifolia, and little is known about the phytochemistry of S. aurita. In this study, winter-dormant twig extracts of S. aurita, S. caprea, and S. pyrolifolia were screened for their antibacterial activities against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Escherichia coli. The antibacterial effects were evaluated using agar diffusion and turbidimetric microplate methods. Time-kill effects were measured using the microplate optical density (OD620) method. UPLC-PDA-QTOF/MS analysis was conducted to identify the polyphenols present in a methanol extract of S. aurita. The antibacterial results show that methanol and hot and cold water twig extracts of S. aurita, S. caprea, and S. pyrolifolia have significant antibacterial effects against P. aeruginosa, S. aureus, and B. cereus with the diameters of the inhibition zones (IZDs) ranging from 16.17 to 30.0 mm and the MICs between 1250 and 2500 µg/mL. Only the cold water extract of S. caprea was moderately active against E. coli. Proanthocyanidins, procyanidin B1 (m/z 577), and procyanidin C1 (m/z 865) were identified as the major polyphenols present in the methanol extract of S. aurita twigs for the first time. Additionally, salicin-7-sulfate was present in S. aurita twigs. Procyanidin B-1, taxifolin, trans-p-hydroxycinnamic acid, and catechin showed growth inhibitory activity against B. cereus with a MIC value of 250 µg/mL.

Protective Effects of Grape Seed Oligomeric Proanthocyanidins in IPEC-J2–Escherichia coli/Salmonella Typhimurium Co-Culture

Intestinal epithelium provides the largest barrier protecting mammalian species from harmful external factors; however, it can be severely compromised by the presence of bacteria in the gastrointestinal (GI) tract. Antibiotics have been widely used for the prevention and treatment of GI bacterial infections, leading to antimicrobial resistance in human and veterinary medicine alike. In order to decrease antibiotic usage, natural substances, such as flavonoids, are investigated to be used as antibiotic alternatives. Proanthocyanidins (PAs) are potential candidates for this purpose owing to their various beneficial effects in humans and animals. In this study, protective effects of grape seed oligomeric proanthocyanidins (GSOPs) were tested in IPEC-J2 porcine intestinal epithelial cells infected with Escherichia coli and Salmonella enterica ser. Typhimurium of swine origin. GSOPs were able to alleviate oxidative stress, inflammation and barrier integrity disruption inflicted by bacteria in the co-culture. Furthermore, GSOPs could decrease the adhesion of both bacteria to IPEC-J2 cells. Based on these observations, GSOPs seem to be promising candidates for the prevention and treatment of gastrointestinal bacterial infections.

Avoiding antibiotics in the management of recurrent UTIs in women: What are our options?

Urinary tract infections are one of the most common infections worldwide, accounting in the United Kingdom for 1–3% of all medical consultations. Fifty per cent of women will experience one episode of urinary tract infection in their lifetimes and of these, up to 30% will develop recurrent urinary tract infections. Such women often rely on long-term low dose antibiotics.

Level of evidence: Not applicable for this multicentre audit.

Oropharyngeal Bacterial Colonization after Chlorhexidine Mouthwash in Mechanically Ventilated Critically Ill Patients

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Oropharyngeal care with chlorhexidine to prevent ventilator-associated pneumonia is currently questioned, and exhaustive microbiologic data assessing its efficacy are lacking. The authors therefore aimed to study the effect of chlorhexidine mouthwash on oropharyngeal bacterial growth, to determine chlorhexidine susceptibility of these bacteria, and to measure chlorhexidine salivary concentration after an oropharyngeal care.

METHODS

This observational, prospective, single-center study enrolled 30 critically ill patients under mechanical ventilation for over 48 h. Oropharyngeal contamination was assessed by swabbing the gingivobuccal sulcus immediately before applying 0.12% chlorhexidine with soaked swabs, and subsequently at 15, 60, 120, 240, and 360 min after. Bacterial growth and identification were performed, and chlorhexidine minimal inhibitory concentration of recovered pathogens was determined. Saliva was collected in 10 patients, at every timepoint, with an additional timepoint after 30 min, to measure chlorhexidine concentration.

RESULTS

Two hundred fifty bacterial samples were analyzed and identified 48 pathogens including Streptococci (27.1%) and Enterobacteriaceae (20.8%). Oropharyngeal contamination before chlorhexidine mouthwash ranged from 10 to 10 colony-forming units (CFU)/ml in the 30 patients (median contamination level: 2.5·10 CFU/ml), and remained between 8·10 (lowest) and 3·10 CFU/ml (highest count) after chlorhexidine exposure. These bacterial counts did not decrease overtime after chlorhexidine mouthwash (each minute increase in time resulted in a multiplication of bacterial count by a coefficient of 1.001, P = 0.83). Viridans group streptococci isolates had the lowest chlorhexidine minimal inhibitory concentration (4 [4 to 8] mg/l); Enterobacteriaceae isolates had the highest ones (32 [16 to 32] mg/l). Chlorhexidine salivary concentration rapidly decreased, reaching 7.6 [1.8 to 31] mg/l as early as 60 min after mouthwash.

CONCLUSIONS

Chlorhexidine oropharyngeal care does not seem to reduce bacterial oropharyngeal colonization in critically ill ventilated patients. Variable chlorhexidine minimal inhibitory concentrations along with low chlorhexidine salivary concentrations after mouthwash could explain this ineffectiveness, and thus question the use of chlorhexidine for ventilator-associated pneumonia prevention.

Oropharyngeal colonization: epidemiology, treatment and ventilator-associated pneumonia prevention

Oropharyngeal (OP) colonization and ventilator-associated pneumonia (VAP) mechanisms are tightly linked. A significant within-population variation in OP colonization has been described, with its composition being dependent from patients' severity. For instance, healthy subjects have a very low rate in Gram-negative bacteria (GNB) colonization, while its rate rises in comorbid patients, reaching high proportions in ICU patients. Various factors can be put forward to explain the modifications of hospital acquired OP. ICU patients might suffer from underlying diseases; the gastric reflux induced by the presence of nasogastric tubes and the patients' position influences OP colonization; salivary composition might influence OP content, as it modulates bacterial adhesion and induces reversible bacterial changes enhancing bacterial binding. The transition from OP colonization to VAP has been shown in numerous studies, with the digestive tract acting as a filter, or as a reservoir. Some therapies have been investigated to modulate OP colonization, in order to reduce the risk for VAP. Among those, mammalian antimicrobial peptides have been shown effective in reducing GNB colonization in healthy subjects, but failed in preventing VAP in ICU patients. The widely used chlorhexidine was tested in numerous trials. Data on its efficacy are conflicting, and meta-analyses yield discordant results. Above all, several drawbacks have aroused: a poor tolerance of concentrated solutions; an increased risk of death in the less severe patients; and a reduced susceptibility towards chlorhexidine of number of VAP pathogens. Proanthocyanidins, used to prevent Escherichia coli adhesion to the urothelium, have been tested in mice model of pneumonia with interesting results. Some complementary data are needed before moving to clinical research. Future research paths should include a reappraisal of OP colonization; finding better formulations for chlorhexidine; define the best populations to target oral decontamination and developing other strategies to prevent and treat OP colonization.

Propolis potentiates the effect of cranberry (Vaccinium macrocarpon) against the virulence of uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC), the most prevalent bacteria isolated in urinary tract infections (UTI), is now frequently resistant to antibiotics used to treat this pathology. The antibacterial properties of cranberry and propolis could reduce the frequency of UTIs and thus the use of antibiotics, helping in the fight against the emergence of antibiotic resistance. Transcriptomic profiles of a clinical UPEC strain exposed to cranberry proanthocyanidins alone (190 µg/mL), propolis alone (102.4 µg/mL) and a combination of both were determined. Cranberry alone, but more so cranberry + propolis combined, modified the expression of genes involved in different essential pathways: down-expression of genes involved in adhesion, motility, and biofilm formation, and up-regulation of genes involved in iron metabolism and stress response. Phenotypic assays confirmed the decrease of motility (swarming and swimming) and biofilm formation (early formation and formed biofilm). This study showed for the first time that propolis potentiated the effect of cranberry proanthocyanidins on adhesion, motility, biofilm formation, iron metabolism and stress response of UPEC. Cranberry + propolis treatment could represent an interesting new strategy to prevent recurrent UTI.

Methods to determine effects of cranberry proanthocyanidins on extraintestinal infections: Relevance for urinary tract health

Urinary tract infections (UTI) are one of the most frequent extraintestinal infections caused by Escherichia coli (ExPEC). Cranberry juice has been used for decades to alleviate symptoms and prevent recurrent UTI. The putative compounds in cranberries are proanthocyanidins (PAC), specifically PAC with "A-type" bonds. Since PAC are not absorbed, their health benefits in UTI may occur through interactions at the mucosal surface in the gastrointestinal tract. Recent research showed that higher agglutination of ExPEC and reduced bacterial invasion are correlated with higher number of "A-type" bonds and higher degree of polymerization of PAC. An understanding of PAC structure-activity relationship is becoming feasible due to advancements, not only in obtaining purified PAC fractions that allow accurate estimation, but also in high-resolution MS methodologies, specifically, MALDI-TOF MS. A recent MALDI-TOF MS deconvolution method allows quantification of the ratios of "A-type" to "B-type" bonds enabling characteristic fingerprints. Moreover, the generation of fluorescently labeled PAC allows visualization of the interaction between ExPEC and PAC with microscopy. These tools can be used to establish structure-activity relationships between PAC and UTI and give insight on the mechanism of action of these compounds in the gut without being absorbed.