Oregano and Thyme Essential Oils Encapsulated in Chitosan Nanoparticles as Effective Antimicrobial Agents against Foodborne Pathogens.

The use of natural compounds with biocidal activity to fight the growth of bacteria responsible for foodborne illness is one of the main research challenges in the food sector. This study reports the preparation and physicochemical characterization of chitosan nanoparticles loaded with Thymus capitatus (Th-CNPs) and Origanum vulgare (Or-CNPs) essential oils. The nanosystems were obtained by ionotropic gelation technique with high encapsulation efficiency (80-83%) and loading capacity (26-27%). Nanoparticles showed a spherical shape, bimodal particle size distribution, and good stability (zeta potential values > 40 mV). The treatment of the nanosuspensions at different temperatures (4 and 40 °C) and storage times (7, 15, 21, and 30 days) did not affect their physicochemical parameters and highlights their reservoir ability for essential oils also under stressful conditions. Both Or-CNPs and Th-CNPs exhibited an enhanced bactericidal activity against foodborne pathogens (S. aureus, E. coli, L. monocytogenes) than pure essential oils. These ecofriendly nanosystems could represent a valid alternative to synthetic preservatives and be of interest for health and food safety.

Bacteriotherapy with Streptococcus salivarius 24SMB and Streptococcus oralis 89a oral spray for children with recurrent streptococcal pharyngotonsillitis: a randomized placebo-controlled clinical study.

PURPOSE: Group A beta-hemolytic Streptococcus (GABHS) causes a recurrent acute pharyngotonsillitis (RAPT) in children. Moreover, the repeated use of antibiotics contributes to its resistance. However, S. Salivarius 24SMB and S. oralis 89a were effective probiotics in other infections. Thus, we decided to evaluate this combination efficacy compared to placebo in RAPT. METHODS: Patients with microbiologically confirmed GABHS were enrolled in this randomized, placebo-controlled trial. They received the aforementioned combination or placebo as an oral spray. We investigated episodes of frequency and duration, need for antibiotics, school days lost, the treatment impact on life quality, treatment compliance and side effects during a 90-day treatment and a 6-month follow-up. RESULTS: We included 41 patients in each group. The mean number of GABHS infection was significantly lower during both study periods for the two groups. However, our treatment group showed a lower rate. Moreover, the probiotic group had a lower mean number and a shorter median duration of GABHS episodes during both study periods than controls. Furthermore, the mean duration of antibiotic treatment was lower in the probiotic group during the 90-day and 6-month follow-up periods. Similarly, patients in the probiotic group showed a significantly lower mean number of absence days from school but higher EQ-VAS score. Indeed, all patients included were compliant to treatment. CONCLUSIONS: We identified potential probiotics, possessing desirable features against GABHS pharyngotonsillitis. Our findings represent the first evidence which throws the light on using these probiotics that can reduce antibiotics use which did not have efficient results regarding recurrence.

Gut Microbiota and Cancer: From Pathogenesis to Therapy.

Cancer is a multifactorial pathology and it represents the second leading cause of death worldwide. In the recent years, numerous studies highlighted the dual role of the gut microbiota in preserving host's health. Gut resident bacteria are able to produce a number of metabolites and bioproducts necessary to protect host's and gut's homeostasis. Conversely, several microbiota subpopulations may expand during pathological dysbiosis and therefore produce high levels of toxins capable, in turn, to trigger both inflammation and tumorigenesis. Importantly, gut microbiota can interact with the host either modulating directly the gut epithelium or the immune system. Numerous gut populating bacteria, called probiotics, have been identified as protective against the genesis of tumors. Given their capability of preserving gut homeostasis, probiotics are currently tested to help to fight dysbiosis in cancer patients subjected to chemotherapy and radiotherapy. Most recently, three independent studies show that specific gut resident species may potentiate the positive outcome of anti-cancer immunotherapy. The highly significant studies, uncovering the tight association between gut microbiota and tumorigenesis, as well as gut microbiota and anti-cancer therapy, are here described. The role of the Lactobacillus rhamnosus GG (LGG), as the most studied probiotic model in cancer, is also reported. Overall, according to the findings here summarized, novel strategies integrating probiotics, such as LGG, with conventional anti-cancer therapies are strongly encouraged.

Insights and clinical perspectives of daptomycin resistance in Staphylococcus aureus: A review of the available evidence.

The emergence of glycopeptide reduced susceptibility and resistance in Staphylococcus aureus strains is a growing clinical problem that poses significant clinical challenges in treatment. Its development is a complex and novel process involving many subtle physiological changes in the micro-organism. Daptomycin is the first cyclic lipopeptide approved for clinical use. Unlike most other antimicrobials, a trend towards increased daptomycin resistance has not been reported, although several cases of daptomycin non-susceptibility have been reported. The present review will present the available evidence on daptomycin resistance of S. aureus, with particular attention to its development. In addition to a literature overview, we have compiled the reported cases of daptomycin non-susceptibility to shed light on possible clinical mechanisms of resistance. In the 36 reports describing 62 clinical cases, infections caused by meticillin-resistant S. aureus (MRSA) strains with a vancomycin minimum inhibitory concentration (MIC) between 1mg/L and 2mg/L often led to vancomycin treatment failure, which may be associated with the development of non-susceptibility to daptomycin. Additional evidence suggests that underdosage of daptomycin is an important clinical aspect that merits further study. The current analysis highlights the importance of determining the MIC when using vancomycin to treat patients with severe S. aureus infections and that when failure is suspected, testing for heterogeneous vancomycin-intermediate S. aureus (hVISA) may also be necessary. Whilst further investigation is needed, it can be hypothesised that MRSA strains become hVISA during prolonged bacteraemia, which may predispose to the development of daptomycin resistance.

Daptomycin plus trimethoprim/sulfamethoxazole combination therapy in post-neurosurgical meningitis caused by linezolid-resistant Staphylococcus epidermidis.

Post-neurosurgical infection is a serious complication that occurs in approx. 4% of all patients undergoing neurosurgical procedures and is associated with high morbidity and mortality rates and prolonged length of intensive care unit (ICU) stay. Coagulase-negative staphylococci (CoNS), especially methicillin-resistant Staphylococcus epidermidis (MRSE), are the most frequent pathogens involved in CNS post-neurosurgical meningitis. Treatment is challenging especially in patients with meningitis due to multidrug- resistant (MDR) CONS. Herein, we report a unique case of post-neurosurgical meningitis due to MRSE resistant to linezolid (a molecular analysis revealed the presence of the mutation G2576T on domain V of the 23S rRNA gene) and with reduced susceptibility to glycopeptides, successfully treated with a combination of daptomycin at 10 mg/kg daily plus trimethoprim/sulfamethoxazole (TMP/SMX). This antibiotic combination showed an indifferent interaction in in vitro studies. Daptomycin serum and cerebrospinal fluid (CSF) concentrations, determined through blood and CSF samples drawn just prior to and 4 h after the third dose, were 18.9-0.78 and 51.65-3.1 mg/L, respectively. These values allowed us to approximate a 5-6% penetration rate of the drug through an inflamed blood-brain barrier. In conclusion, although further studies are needed, combination of high-dose daptomycin plus TMP/SMX is a reasonable option for treatment of meningitis caused by multidrug-resistant S. epidermidis.

Infections with VIM-1 metallo-{beta}-lactamase-producing enterobacter cloacae and their correlation with clinical outcome.

The aim of this study was to ascertain the incidence and clinical significance of metallo-beta-lactamases among Enterobacter strains isolated from patients with nosocomial infections. We prospectively collected data on patients with Enterobacter infection during a 13-month period. All of the strains were investigated for antibiotic susceptibility, the presence and expression of metallo-beta-lactamases, and clonality. Of 29 infections (11 involving the urinary tract, 7 pneumonias, 3 skin/soft tissue infections, 3 intra-abdominal infections, 3 bacteremias, and 2 other infections), 7 (24%) were caused by Enterobacter cloacae strains harboring a bla(VIM-1) gene associated or not with a bla(SHV12) gene. Infections caused by VIM-1-producing strains were more frequently associated with a recent prior hospitalization (P = 0.006), cirrhosis (P = 0.03), relapse of infection (P < 0.001), and more prolonged duration of antibiotic therapy (P = 0.01) than were other infections. All of the isolates were susceptible to imipenem and meropenem and had bla(VIM-1) preceded by a weak P1 promoter and inactivated P2 promoters. Most VIM-1-producing Enterobacter isolates belonged to a main clone, but four different clones were found. Multiclonal VIM-1-producing E. cloacae infections are difficult to diagnose due to an apparent susceptibility to various beta-lactams, including carbapenems, and are associated with a high relapse rate and a more prolonged duration of antibiotic therapy.

[Etiology, epidemiology and microbiological diagnosis of intra-abdominal infections]. / Eziologia, epidemiologia e diagnostica microbiologica delle infezioni intraddominali.

Intra-abdominal infections (IAIs) are commonly encountered in clinical practice. The etiology of these infections, often polymicrobial in nature, can be variable and usually includes organisms derived from the gut microbiota. In community-acquired IAIs enterobacteria predominate (mostly Escherichia coli) in combination with anaerobes (mostly Bacteroides fragilis). In nosocomial IAIs, which can complicate abdominal surgery, other pathogens can also play a role, such as Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus spp. e Candida spp. Diagnostic microbiology of IAIs is complex and plays a relevant role especially in some situations (e. g. presence of foreign bodies, potential presence of resistant or uncommon pathogens, nosocomial infections in subjects with risk factors). Antibiotic resistance issues are currently encountered in most pathogenic species causing IAIs. Resistance affects all major classes of antimicrobial agents, often involving multiple classes and resulting in complex resistance phenotypes for which only a very limited number of drugs remain active.