Bacteriocins, Antimicrobial Peptides from Bacterial Origin: Overview of Their Biology and Their Impact against Multidrug-Resistant Bacteria.

Currently, the emergence and ongoing dissemination of antimicrobial resistance among bacteria are critical health and economic issue, leading to increased rates of morbidity and mortality related to bacterial infections. Research and development for new antimicrobial agents is currently needed to overcome this problem. Among the different approaches studied, bacteriocins seem to be a promising possibility. These molecules are peptides naturally synthesized by ribosomes, produced by both Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), which will allow these bacteriocin producers to survive in highly competitive polymicrobial environment. Bacteriocins exhibit antimicrobial activity with variable spectrum depending on the peptide, which may target several bacteria. Already used in some areas such as agro-food, bacteriocins may be considered as interesting candidates for further development as antimicrobial agents used in health contexts, particularly considering the issue of antimicrobial resistance. The aim of this review is to present an updated global report on the biology of bacteriocins produced by GPB and GNB, as well as their antibacterial activity against relevant bacterial pathogens, and especially against multidrug-resistant bacteria.

Prescription errors related to the use of computerized provider order-entry system for pediatric patients.

OBJECTIVES: To evaluate the nature and frequency of medication errors resulting from the use of a computerized provider order-entry (CPOE) system in a pediatric department. METHODS: We conducted a retrospective study to examine errors related to computerized orders using the software Pharma® (Computer Engineering, France) in pediatric department between 31/05/2015 to 01/12/2015. These errors were signaled by pharmacists who examine CPOEs daily. RESULTS: A total of 302 pharmacist interventions (PharmInt) were carried out by clinical pharmacists during the study period. Of the 302 PharmInts, a total of 95 (31.5%) contained no data on the patient's bodyweight, which should have been provided by the prescriber (Table 1). After the PharmInt, information on bodyweight was then provided in 47 of these cases (15.6%). Incomplete information about administration frequency accounted for 19.9% of total PharmInts. Prescribing an excessive dose occurred in 17.6% of PharmInts, inappropriate modifications of prescription unit accounted for 9.9% of PharmInts, and incorrect dosage was prescribed in 8.3% of PharmInts. Of the 302 PharmInts, 255 concerned prescription errors and bodyweight missing not provided after PharmInt. Paracetamol, in its different forms (injectable, solid or liquid oral forms) accounted for 35.7% of total PharmInts. Noted errors for paracetamol included an incorrect dosage form, co-administration of two paracetamol-containing drugs, modification of the prescription unit, incorrect frequency of administrations, and absence of the patient's bodyweight. Inconsistent use of a contradicted or a non-used drug for pediatric patients was noted along with prescriptions for inadequate dosages. DISCUSSION AND CONCLUSION: Our work revealed several error types in prescribing for pediatric patients, mainly absence of bodyweight, incorrect frequency of administration and excessive doses. Information on bodyweight is crucial in pediatric patients: our study highlights the need to make it mandatory to complete prescriptions via CPOE systems. The role of better software design is pivotal to avoiding these errors. In addition to optimizing the quality of CPOE-entries, well-designed software, better-trained users, and improved communication among healthcare will reduce errors.

Recent advances in ocular drug delivery.

Amongst the various routes of drug delivery, the field of ocular drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist. Recent research has focused on the characteristic advantages and limitations of the various drug delivery systems, and further research will be required before the ideal system can be developed. Administration of drugs to the ocular region with conventional delivery systems leads to short contact time of the formulations on the epithelium and fast elimination of drugs. This transient residence time involves poor bioavailability of drugs which can be explained by the tear production, non-productive absorption and impermeability of corneal epithelium. Anatomy of the eye is shortly presented and is connected with ophthalmic delivery and bioavailability of drugs. In the present update on ocular dosage forms, chemical delivery systems such as prodrugs, the use of cyclodextrins to increase solubility of various drugs, the concept of penetration enhancers and other ocular drug delivery systems such as polymeric gels, bioadhesive hydrogels, in-situ forming gels with temperature-, pH-, or osmotically induced gelation, combination of polymers and colloidal systems such as liposomes, niosomes, cubosomes, microemulsions, nanoemulsions and nanoparticles are discussed. Novel ophthalmic delivery systems propose the use of many excipients to increase the viscosity or the bioadhesion of the product. New formulations like gels or colloidal systems have been tested with numerous active substances by in vitro and in vivo studies. Sustained drug release and increase in drug bioavailability have been obtained, offering the promise of innovation in drug delivery systems for ocular administration. Combining different properties of pharmaceutical formulations appears to offer a genuine synergy in bioavailability and sustained release. Promising results are obtained with colloidal systems which present very comfortable conditions of use and prolonged action.

Comparative in vitro performance of three small-volume valved holding chambers with beclomethasone/formoterol pressurized metered dose inhaler.

BACKGROUND: The use of valved holding chambers (VHCs) with pressurized metered dose inhalers (pMDIs) is reported to reduce the oral deposition of inhaled drugs and to facilitate the handling of these devices by patients, especially children. Although the number of commercially available VHCs is increasing, the correct choice of VHC in clinical practice is important, because VHCs are not equally effective regarding medication delivery. Hence, we aimed to evaluate the use of three small-volume VHCs-Vortex(®), AeroChamber(®) Plus (ACP), and Able Spacer™ (AS)-along with a commercial pMDI containing a combination of beclomethasone and formoterol (Innovair(®)) frequently used by asthma patients. METHODS: Evaluation of the delivered dose of both drugs and analysis of particle size distribution of aerosols emitted for the inhaler were performed using the Next Generation Impactor with and without the tested VHCs. RESULTS: The VHCs retained significant quantities of both drugs and dramatically reduced the quantity of drugs deposited in the throat of the impactor, indicating that particles with large size were preferably retained in the VHCs. Interestingly, although the delivered dose of both drugs was reduced by the use of VHCs, the use of the Vortex and the ACP resulted in comparable fine particle doses (FPDs) to that obtained when the pMDI was used alone, whereas the AS VHC significantly reduced the FPDs of both drugs. This may be due to the fact that, unlike the AS VHC, the Vortex and the ACP VHCs are made of antistatic materials that minimize the electrostatic interaction with emitted aerosols, enhancing medication delivery. CONCLUSION: The Vortex and the ACP VHCs present interesting advantages over the AS VHC to be used with Innovair pMDI. However, these results are based on an in vitro evaluation and need to be validated in an in vivo study in order to clinically assess the performance of these VHCs.

In vitro activity of aminosterols against dermatophytes.

We recently reported that aminosterols are fungicidal due to their disrupting the outer membranes of yeasts and that they have a significant in vitro activity against various mould species. Yet, their activity against dermatophytes had never been tested. This study's objective was to evaluate the in vitro activity of squalamine and a synthetic aminosterol derivative (ASD) against various dermatophytes. Susceptibility testing of squalamine, ASD, terbinafine, and griseofulvin was performed, in triplicate, in accord with the Clinical Laboratory and Standards Institute's M38-A2 procedure, using an 80% growth inhibition endpoint. The studies included the following dermatophytes: Trichophyton rubrum, T. mentagrophytes, T. soudanense, Microsporum canis, M. audouinii, M. persicolor; M. cookie and M. gypseum. Squalamine and ASD showed significant in vitro activity against these dermatophytes. The minimum inhibitory concentrations (MICs) ranged from 4-16 mg/l and from 2-8 mg/l for squalamine and ASD, respectively. These findings support further clinical studies of aminosterols activity against superficial dermatophyte infections.

Soluble squalamine tablets for the rapid disinfection of home nebulizers of cystic fibrosis patients.

BACKGROUND: The bacterial contamination of nebulizers represents a major problem for cystic fibrosis (CF) patients that can lead to reduced nebulizer performance and increase the risk of patient reinfection by the contaminating bacteria. OBJECTIVE: We investigated the potential use of squalamine, a broad-spectrum antimicrobial compound, as a nebulizer disinfectant. METHODS: Pari LC nebulizers were artificially contaminated with a suspension of bacteria (Staphylococcus aureus and Pseudomonas aeruginosa; 10(8) CFU/mL) and fungi (Candidida albicans and Aspergilus niger; 10(7) CFU/mL) and then disinfected by immersion in squalamine solution for 20 min. Glutaraldehyde and Korsolex peracetic acid were used as disinfectant controls. RESULT: We found that 0.5 g/L squalamine reduced the levels of viable S. aureus and P. aeruginosa by 5 log(10) and the level of viable C. albicans by 4 log(10) after 20 min. A concentration of 2 g/L was needed to reduce the level of A. niger cells by 4 log(10) in 6 hours. Finally, a formulation of squalamine in the form of a soluble disinfecting tablet containing 2.5% (w/w) squalamine was developed and successfully applied for nebulizer disinfection. CONCLUSION: Our results suggest that aminosterol derivatives may be used by CF patients for rapid and easy home nebulizer disinfection and that soluble tablets may be developed for this purpose.

Suitability of a new antimicrobial aminosterol formulation for aerosol delivery in cystic fibrosis.

OBJECTIVES: We evaluated the suitability of an aminosterol derivative (ASD), possessing interesting in vitro antimicrobial activities against various resistant pathogens involved in lung infections of cystic fibrosis patients, for aerosol drug delivery. METHODS: The suitability of 2 and 10 mg/mL ASD solutions for aerosol delivery was evaluated and compared with that of a commercial inhalable solution of tobramycin using Pari LC Plus and eFlow rapid nebulizers. Physicochemical properties of ASD solutions, including pH and osmolarity, were assessed. The particle size distribution of the aerosols was analysed using a laser diffraction method. Effects of mucin on the in vitro antibacterial activities of ASD solutions and tobramycin were assessed using the broth dilution method for MIC determination. RESULTS: MICs of ASD and tobramycin for Pseudomonas aeruginosa ATCC 27853 were 4 and 1 mg/L, respectively, and those for Staphylococcus aureus ATCC 25923 were 1 and 0.5 mg/L, respectively. MICs of tobramycin increased at least 4- and 16-fold for both bacteria after addition of mucin at 1 and 10 mg/mL, respectively, while MICs of ASD remained unchanged. ASD solutions should be prepared in 0.9% NaCl solution in order to produce an isotonic state, and need the addition of NaOH to give a suitable pH value for inhalation. ASD solutions were successfully nebulized using both nebulizers, as reflected by the similarity of the aerodynamic parameters to those of a commercial tobramycin solution. CONCLUSIONS: This introductory study demonstrates the suitability of ASDs for aerosol delivery and calls for further work to evaluate such formulations using a lung-infected animal model.

Squalamine ointment for Staphylococcus aureus skin decolonization in a mouse model.

OBJECTIVES: Staphylococcus aureus colonization of the skin and the nostrils remains a major cause of surgical-site infections despite preoperative and preventive procedures. To date, many compounds have been used for S. aureus decolonization, including mupirocin ointments and antiseptics, with variable results. The emergence of mupirocin-resistant S. aureus strains has led to the search for new antimicrobial agents specifically for S. aureus decolonization. In this work we evaluated squalamine and related parent-derived ointments (1%) as potential new compounds for S. aureus decolonization in a new mouse model. METHODS: We report the development and application of squalamine and related parent-derived ointments in a new mouse skin model. After skin shaving, mice were colonized with an S. aureus suspension that was calibrated to 104-106 cfu/mL. The remaining bacterial load was monitored for 2 days after a single application of squalamine by spreading. RESULTS: We found that S. aureus colonization of the skin was stable for at least 2 days before it was naturally eliminated. Using this model we found that squalamine ointment (1%) could reduce S. aureus viable cells by up to 4 log with a single, 1 h application of ointment, whereas mupirocin application reduced viable cell numbers by only 1.3 log during that same time (P < 0.05). CONCLUSIONS: Our results suggest that such compounds may be useful for S. aureus nasal and skin decolonization and may constitute a potent alternative for skin and nasal antisepsis before surgery.

In vitro activity of aminosterols against yeasts involved in blood stream infections.

Squalamine and other aminosterols have demonstrated interesting antimicrobial activities against clinical bacterial isolates and a limited number of reference yeast strains. We aimed to test whether squalamine and a synthetic aminosterol derivative (ASD) display any in vitro activity comparable to currently available systemic antifungals, an acceptable safety index, as well as to provide insights into their mechanism of action. The minimum inhibitory concentrations (MICs) of squalamine, ASD and available antifungals were determined against 21 yeast isolates that were recovered from cases of fungemia. Remarkably, homogeneous MICs ranging from 8-16 mg/L and from 1-2 mg/L were noted for squalamine and ASD, respectively, as opposes the heterogeneous in vitro activity of available systemic antifungals. Aminosterols induced haemolysis, a surrogate for toxic effects to mammalian cells, at concentrations high above their MICs. In time-kill studies, killing was as fast with ASD as with amphotericin B. Both aminosterols induced a time-dependent disruption of yeast membrane, as evidenced by gradual increase of ATP efflux. In conclusion, our preliminary data indicate that aminosterols have the potential to be further developed as antifungals. Additional work is warranted to assess their toxicity and activity in experimental models.

New insights into the antibacterial mechanism of action of squalamine.

OBJECTIVES: Antimicrobial resistance is an increasingly life-threatening problem that emphasizes the need to develop new antibacterial agents. The in vitro antibacterial activity of squalamine, a natural aminosterol, has been previously demonstrated against multidrug-resistant bacteria and moulds. Although the antibacterial activity of squalamine was found to correlate with that of other drugs, such as colistin, against Gram-negative bacteria, the former was active against Gram-positive bacteria, which are resistant to colistin. In this work, we provide new insights into squalamine's antibacterial mechanism of action compared with other known antibiotics. METHODS: We evaluated squalamine's antibacterial mechanism of action using the broth microdilution method for MIC determination and time-kill assays, transmission electron microscopy for morphological change studies, bioluminescence for ATP release measurements and fluorescence methods for membrane depolarization assays. RESULTS: Concerning Gram-negative bacteria, squalamine, similar to colistin, required interaction with the negatively charged phosphate groups in the bacterial outer membrane as the first step in a sequence of different events ultimately leading to the disruption of the membrane. Conversely, squalamine exhibited a depolarizing effect on Gram-positive bacteria, which resulted in rapid cell death. CONCLUSIONS: The new insights into the mechanism of action of squalamine highlight the importance of aminosterols in the design of a new class of antibacterial compounds that could be used as disinfectants and detergents.

In vitro antibacterial activity of aminosterols against multidrug-resistant bacteria from patients with cystic fibrosis.

OBJECTIVES: Respiratory infections with multidrug-resistant (MDR) bacteria are life-threatening in patients with cystic fibrosis (CF). Squalamine and aminosterol derivatives (ASDs) have previously demonstrated interesting antibacterial activity against bacterial reference strains. This study investigated for the first time their activity against MDR clinical isolates recovered from the sputa of CF patients. METHODS: Antibacterial activity of squalamine and two ASDs (1 and 2) was evaluated against 135 MDR gram-negative and gram-positive bacteria using the broth microdilution method for MIC determination. RESULTS: For gram-negative bacteria, MICs ranged from 2 to 128 mg/L. Resistance to colistin and mucoidity were significantly associated with higher MICs of squalamine and ASDs 1 and 2. Tested compounds were active against various gram-positive bacteria with MIC values varying from 0.5 to 8 mg/L, with the exception of two capsulated isolates of Streptococcus pneumoniae demonstrating MICs of 32 mg/L. CONCLUSIONS: In this study, we present new findings concerning the antibacterial potential of ASDs against MDR bacteria. Colistin-resistant, mucoid and capsulated bacteria were found to exhibit decreased susceptibility to ASDs indicating that these compounds might share some mechanistic aspects with polymyxins towards gram-negative bacteria. However, ASDs were remarkably active against gram-positive species suggesting different mechanisms of action towards gram-positive and gram-negative bacteria. As tested ASDs exhibited elevated MICs in some cases, we believe that these compounds may be developed to be locally administrated as aerosols rather than via systemic administration routes. Further work is warranted to evaluate their in vivo efficacy in aerosol formulations using a lung-infected animal model.