Albert Sotto

Dosage effect on uropathogenic Escherichia coli anti-adhesion activity in urine following consumption of cranberry powder standardized for proanthocyanidin content: a multicentric randomized double blind study

BackgroundIngestion of cranberry (Vaccinium macrocarpon Ait.) has traditionally been utilized for prevention of urinary tract infections. The proanthocyanidins (PACs) in cranberry, in particular the A-type linkages have been implicated as important inhibitors of primarily P-fimbriated E. coli adhesion to uroepithelial cells. Additional experiments were required to investigate the persistence in urine samples over a broader time period, to determine the most effective dose per day and to determine if the urinary anti-adhesion effect following cranberry is detected within volunteers of different origins.MethodsTwo separate bioassays (a mannose-resistant hemagglutination assay and an original new human T24 epithelial cell-line assay) have assessed the ex-vivo urinary bacterial anti-adhesion activity on urines samples collected from 32 volunteers from Japan, Hungary, Spain and France in a randomized, double-blind versus placebo study. An in vivo Caenorhabditis elegans model was used to evaluate the influence of cranberry regimen on the virulence of E. coli strain.ResultsThe results indicated a significant bacterial anti-adhesion activity in urine samples collected from volunteers that consumed cranberry powder compared to placebo (p < 0.001). This inhibition was clearly dose-dependent, prolonged (until 24 h with 72 mg of PAC) and increasing with the amount of PAC equivalents consumed in each cranberry powder regimen. An in vivo Caenorhabditis elegans model showed that cranberry acted against bacterial virulence: E. coli strain presented a reduced ability to kill worms after a growth in urines samples of patients who took cranberry capsules. This effect is particularly important with the regimen of 72 mg of PAC.ConclusionsAdministration of PAC-standardized cranberry powder at dosages containing 72 mg of PAC per day may offer some protection against bacterial adhesion and virulence in the urinary tract. This effect may offer a nyctohemeral protection.

Risk Factors for Antibiotic-Resistant Escherichia coli Isolated from Hospitalized Patients with Urinary Tract Infections: a Prospective Study

ABSTRACT From November 1998 to February 1999 we prospectively evaluated the prevalence of resistance to penicillins, cephalosporins, carbapenem, quinolones, aminoglycosides, and trimethoprim-sulfamethoxazole (SXT) in 320 Escherichia coli isolates isolated from hospitalized patients with acute urinary tract infections (UTIs). We also studied for these strains risk factors for resistance to amoxicillin-clavulanic acid (AMC), fluoroquinolones (FQs), and SXT. Resistance rates were consistent with those from major recent studies reported in the literature. Multivariate analyses selected the following factors as being significantly associated with E. coli resistance: (i) for resistance to AMC, prior (1 year) UTI (odds ratio [OR] = 2.71,P = 0.006), prior (1 year) urinary catheter (OR = 2.98, P = 0.0025), and prior (6 months) antibiotic exposure (OR = 2.68, P = 0.005); (ii) for resistance to FQs male sex (OR = 3.87, P = 0.03), with a trend toward significance for age >65 years (OR = 7.67,P = 0.06) and prior (1 year) UTI (OR = 2.98,P = 0.07); and (iii) for resistance to SXT, male sex (OR = 1.91, P = 0.046), hospitalization in an intermediate-term-care unit (OR = 2.18, P = 0.008), and prior (1 year) UTI (OR = 2.03, P = 0.03). Ours results suggest that prior UTI is a common risk factor for resistance to the different antibiotics tested. Although few studies on risk factors for E. coli resistance to antibiotics have been published, careful interpretation of their findings, taking into consideration the population, infection site, and period studied, should contribute to the formulation of a better strategy that can be used to overcome antibiotic resistance.

Serum procalcitonin and C-reactive protein concentrations to distinguish mildly infected from non-infected diabetic foot ulcers: a pilot study

Aims/hypothesisInfection of diabetic foot ulcers is common; at early stages it is difficult to differentiate between non-infected ulcers (or those colonised with normal flora) and ulcers infected with virulent bacteria that lead to deterioration. This pilot study aimed to assess the diagnostic accuracy of inflammatory markers as an aid to making this distinction.MethodsWe included 93 diabetic patients who had an episode of foot ulcer and had not received antibiotics during the 6 months preceding the study. Ulcers were classified as infected or uninfected, according to the Infectious Diseases Society of America–International Working Group on the Diabetic Foot classification. Diabetic patients without ulcers (n = 102) served as controls. C-reactive protein (CRP), orosomucoid, haptoglobin and procalcitonin were measured together with white blood cell and neutrophil counts. The diagnostic performance of each marker, in combination (using logistic regression) or alone, was assessed.ResultsAs a single marker, CRP was the most informative for differentiating grade 1 from grade 2 ulcers (sensitivity 0.727, specificity 1.000, positive predictive value 1.000, negative predictive value 0.793) with an optimal cut-off value of 17 mg/l. In contrast, white blood cell and neutrophil counts were not predictive. The most relevant combination derived from the logistic regression was the association of CRP and procalcitonin (AUC 0.947), which resulted in a significantly more effective determination of ulcer grades, as shown by comparing receiver operating characteristic curves.Conclusions/interpretationMeasurement of only two inflammatory markers, CRP and procalcitonin, might be of value for distinguishing between infected and non-infected foot ulcers in subgroups of diabetic patients, to help ensure the appropriate allocation of antibiotic treatment. Nevertheless, external validation of the diagnostic value of procalcitonin and CRP in diabetic foot ulcers is needed before routine use can be recommended.

In‐vitro and in‐vivo evidence of dose‐dependent decrease of uropathogenic Escherichia coli virulence after consumption of commercial Vaccinium macrocarpon (cranberry) capsules

This study evaluated the antibacterial efficacy of the consumption of cranberry capsules vs. placebo in the urine of healthy volunteers. A first double-blind, randomised, crossover trial involved eight volunteers who had followed three regimens, with or without cranberry, with a wash-out period of at least 6 days between each regimen. Twelve hours after consumption of cranberry or placebo hard capsules, the first urine of the morning was collected. Different Escherichia coli strains were cultured in the urine samples. Urinary antibacterial adhesion activity was measured in vitro using the human T24 epithelial cell-line, and in vivo using the Caenorhabditis elegans killing model. With the in-vitro model, 108 mg of cranberry induced a significant reduction in bacterial adherence to T24 cells as compared with placebo (p <0.001). A significant dose-dependent decrease in bacterial adherence in vitro was noted after the consumption of 108 and 36 mg of cranberry (p <0.001). The in-vivo model confirmed that E. coli strains had a reduced ability to kill C. elegans after growth in the urine of patients who consumed cranberry capsules. Overall, these in-vivo and in-vitro studies suggested that consumption of cranberry juice represents an interesting new strategy to prevent recurrent urinary tract infection.

Virulence Potential and Genomic Mapping of the Worldwide Clone Escherichia coli ST131

Recently, the worldwide propagation of clonal CTX-M-15-producing Escherichia coli isolates, namely ST131 and O25b:H4, has been reported. Like the majority of extra-intestinal pathogenic E. coli isolates, the pandemic clone ST131 belongs to phylogenetic group B2, and has recently been shown to be highly virulent in a mouse model, even though it lacks several genes encoding key virulence factors (Pap, Cnf1 and HlyA). Using two animal models, Caenorhabditis elegans and zebrafish embryos, we assessed the virulence of three E. coli ST131 strains (2 CTX-M-15- producing urine and 1 non-ESBL-producing faecal isolate), comparing them with five non-ST131 B2 and a group A uropathogenic E. coli (UPEC). In C. elegans, the three ST131 strains showed intermediate virulence between the non virulent group A isolate and the virulent non-ST131 B2 strains. In zebrafish, the CTX-M-15-producing ST131 UPEC isolates were also less virulent than the non-ST131 B2 strains, suggesting that the production of CTX-M-15 is not correlated with enhanced virulence. Amongst the non-ST131 B2 group isolates, variation in pathogenic potential in zebrafish embryos was observed ranging from intermediate to highly virulent. Interestingly, the ST131 strains were equally persistent in surviving embryos as the non-ST131-group B2 strains, suggesting similar mechanisms may account for development of persistent infection. Optical maps of the genome of the ST131 strains were compared with those of 24 reference E. coli strains. Although small differences were seen within the ST131 strains, the tree built on the optical maps showed that these strains belonged to a specific cluster (86% similarity) with only 45% similarity with the other group B2 strains and 25% with strains of group A and D. Thus, the ST131 clone has a genetic composition that differs from other group B2 strains, and appears to be less virulent than previously suspected.

Turkey: a further country concerned by community-acquired Escherichia coli clone O25-ST131 producing CTX-M-15

OBJECTIVES The aim of this study was to assess the frequency and diversity of extended-spectrum beta-lactamases (ESBLs) produced by exclusively community-acquired Escherichia coli isolates in Izmir (Turkey) and to search for isolates producing CTX-M-15 and belonging to the pandemic clone E. coli O25-ST131. METHODS The patients with E. coli urinary tract infections (UTIs) and no hospitalization in the last 12 months, and no transfer from hospital, no stay in nursing home and no antimicrobial treatment in the previous 3 months were prospectively included over a 1 year period. Those E. coli detected positive for ESBL were characterized and compared with a representative of E. coli clone O25-ST131 with regard to bla genes, antibiotic resistance, phylogenetic groups, PFGE profiles and virulence factor genes (n = 17). O serotyping, multilocus sequence typing (MLST) and AmpC typing were performed to confirm that the Turkish isolate belonged to the clone O25-ST131. RESULTS Among the 3108 UTIs diagnosed, 82 (2.6%) were due to community E. coli isolates and followed the strict inclusion criteria. Seventeen of them (21%) produced an ESBL, of which CTX-M-15 was predominant (53%). These ESBL-positive isolates, distributed equally into three phylogenetic groups, displayed 13 PFGE profiles and three clusters. A Turkish CTX-M-15-producing isolate as a member of the clone ST131 was suggested by a high similarity of its PFGE profile to that of the clone representative and was confirmed by O serotyping, AmpC typing and MLST. CONCLUSIONS This study describes the community emergence of CTX-M-15-producing E. coli isolates, including an isolate of clone O25-ST131, in Turkey.

Epidemiology of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii in Mediterranean countries.

The emergence and global spread of carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii are of great concern to health services worldwide. These β-lactamases hydrolyse almost all β-lactams, are plasmid-encoded, and are easily transferable among bacterial species. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 types. Their current extensive spread worldwide in Enterobacteriaceae is an important source of concern. Infections caused by these bacteria have limited treatment options and have been associated with high mortality rates. Carbapenemase producers are mainly identified among Klebsiella pneumoniae, Escherichia coli, and A. baumannii and still mostly in hospital settings and rarely in the community. The Mediterranean region is of interest due to a great diversity and population mixing. The prevalence of carbapenemases is particularly high, with this area constituting one of the most important reservoirs. The types of carbapenemase vary among countries, partially depending on the population exchange relationship between the regions and the possible reservoirs of each carbapenemase. This review described the epidemiology of carbapenemases produced by enterobacteria and A. baumannii in this part of the world highlighting the worrisome situation and the need to screen and detect these enzymes to prevent and control their dissemination.

Phosphonate monolayers functionalized by silver thiolate species as antibacterial nanocoatings on titanium and stainless steel

Titanium and stainless steel substrates were modified by grafting with mercaptododecylphosphonic acid (MDPA) followed by reaction with silver nitrate (AgNO3), in order to investigate the potential of phosphonate self-assembled monolayers functionalized by silver thiolate species as antibacterial nanocoatings for inorganic biomaterials. The samples were characterized by Fourier transform infrared (FTIR) spectroscopy in grazing-incidence mode, water contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The influence of the surface modification on bacterial adhesion and biofilm growth was investigated in vitro using Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus strains. The stability of the monolayer in blood-mimicking medium was examined. Despite their very low silver content, MDPA + AgNO3 monolayers strongly decreased bacterial adhesion (>99.9% reduction in the number of viable adherent bacteria) and biofilm formation in comparison to the bare substrates.

Virulence Potential of Staphylococcus aureus Strains Isolated From Diabetic Foot Ulcers: A new paradigm

OBJECTIVE—The purpose of this study was to assess the virulence potential of Staphylococcus aureus strains isolated from diabetic foot ulcers and to discriminate noninfected from infected ulcers. RESEARCH DESIGN AND METHODS—Diabetic patients hospitalized in a diabetic foot department with a foot ulcer were prospectively enrolled if they had been free of antibiotic treatment over the previous 6 months. At admission, ulcers were classified as infected or noninfected on the basis of clinical examination, according to the International Working Group on the Diabetic Foot system. Only patients carrying S. aureus as the sole pathogen were included. In individuals with a grade 1 ulcer, a second bacterial specimen was obtained 1 month later. Using virulence genotyping markers, clonality tools, and an in vivo Caenorhabditis elegans model, we correlated the virulence of 132 S. aureus strains with grade, time of collection, and ulcer outcome. RESULTS—Among virulence genes, the most relevant combination derived from the logistic regression was the association of cap8, sea, sei, lukE, and hlgv (area under the curve 0.958). These markers were useful to distinguish noninfected (grade 1) from infected (grades 2–4) ulcers and to predict wound status at the follow-up. With use of the nematode model, S. aureus strains isolated from grade 1 ulcers were found to be significantly less virulent than strains from ulcers at or above grade 2 (P < 0.001). CONCLUSIONS—This study highlights the coexistence of two S. aureus populations on diabetic foot ulcers. A combination of five genes that may help distinguish colonized grade 1 from infected grade ≥2 wounds, predict ulcer outcome, and contribute to more appropriate use of antibiotics was discovered.

New insights in diabetic foot infection

Foot ulcers are common in diabetic patients, have a cumulative lifetime incidence rate as high as 25% and frequently become infected. The spread of infection to soft tissue and bone is a major causal factor for lower-limb amputation. For this reason, early diagnosis and appropriate treatment are essential, including treatment which is both local (of the foot) and systemic (metabolic), and this requires coordination by a multidisciplinary team. Optimal treatment also often involves extensive surgical debridement and management of the wound base, effective antibiotic therapy, consideration for revascularization and correction of metabolic abnormalities such as hyperglycemia. This article focuses on diagnosis and management of diabetic foot infections in the light of recently published data in order to help clinicians in identification, assessment and antibiotic therapy of diabetic foot infections.