Niosomes are promising for enhanced antibacterial activity and reduced resistance to antibiotics. The later can be achieved by inhibition of biofilm formation.

Benzalkonium chloride (BAC) is widely used as a disinfectant and preservative. This study investigated the effect on antimicrobial susceptibility and the cellular changes that occurred after exposure of Klebsiella pneumoniae clinical isolates to sublethal concentrations of BAC. Minimum inhibitory concentration and minimum bactericidal concentration of BAC were determined for the collected 50 K. pneumoniae clinical isolates by broth microdilution method, and the tested isolates were adapted to increasing sublethal concentrations of BAC. The effect of adaptation on MICs of the tested 16 antimicrobial agents, the cell ultrastructure, efflux, and membrane depolarization of the tested isolates were examined. Interestingly, most K. pneumoniae isolates that adapted to BAC showed increased antimicrobial resistance, various morphological and structural changes, increased membrane depolarization, and enhanced efflux activity. The findings of this study suggest that the extensive use of BAC at sublethal concentrations could contribute to the emergence of antibiotic resistance in K. pneumoniae clinical isolates that might complicate the therapy of infections caused by this pathogen. In conclusion, the hazard associated with the prolonged exposure to sublethal concentrations of BAC represents a public health risk and therefore it should be a focus in both hospital and community sanitation practices.

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We examined a total of 150 samples, including 27 eye shadows, 27 mascaras and 96 face creams, for their microbial contents. Mascaras were generally more contaminated than eye shadows. More than 75% of the examined eye shadows contained fewer than 100 c.f.u./g aerobic bacterial count compared to 63% of the mascaras examined. Viable bacteria were not recovered from 61% and 48% of the eye shadows and mascaras respectively. While 4% of the eye shadows were heavily contaminated (contained more than 10(4) c.f.u./g), 15% of the mascaras were as heavily contaminated (with more than 10(4) c.f.u./ml of bacteria). Face creams were generally more heavily contaminated than eye shadows and mascaras. More than 70% of the examined creams contained more than 100 c.f.u./g of bacteria compared to 23% and 37% of eye shadows and mascaras respectively. Only 5% of the face creams were heavily contaminated. However, 27% of the creams were contaminated with more than 10(3)-10(4) c.f.u./g of bacteria compared to none in this range for both eye shadows and mascaras. Qualitative tests for detection of hazardous bacteria showed that none of the eye shadows were contaminated with any of those micro-organisms. Out of nine items of a specific brand of mascara, three isolates of Pseudomonas aeruginosa, one isolate of Citrobacter freundii and one isolate of Klebsiella pneumonia were detected. Among the creams, two brands showed the highest contamination levels with more than 85% of the tested samples containing more than 10(3) c.f.u./g fungi and at least 10(4) c.f.u./g bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Background Antibiotic resistance in pathogenic bacterial isolates has increased worldwide leading to treatment failures. Main body Many concerns are being raised about the usage of biocidal products (including disinfectants, antiseptics, and preservatives) as a vital factor that contributes to the risk of development of antimicrobial resistance which has many environmental and economic impacts. Conclusion Consequently, it is important to recognize the different types of currently used biocides, their mechanisms of action, and their potential impact to develop cross-resistance and co-resistance to various antibiotics. The use of biocides in medical or industrial purposes should be monitored and regulated. In addition, new agents with biocidal activity should be investigated from new sources like phytochemicals in order to decrease the emergence of resistance among bacterial isolates.

Background The percentage of the multidrug resistant Klebsiella pneumoniae clinical isolates is increasing worldwide. The excessive exposure of K. pneumoniae isolates to sublethal concentrations of biocides like benzalkonium chloride (BAC) in health care settings and communities could be one of the causes contributing in the global spread of antibiotic resistance. Results We collected 50 K. pneumoniae isolates and these isolates were daily exposed to gradually increasing sublethal concentrations of BAC. The consequence of adaptation to BAC on the cell surface hydrophobicity (CSH) and biofilm formation of K. pneumoniae isolates was explored. Remarkably, 16% of the tested isolates showed an increase in the cell surface hydrophobicity and 26% displayed an enhanced biofilm formation. To evaluate whether the influence of BAC adaptation on the biofilm formation was demonstrated at the transcriptional level, the RT-PCR was employed. Noteworthy, we found that 60% of the tested isolates exhibited an overexpression of the biofilm gene (bssS). After sequencing of this gene in K. pneumoniae isolates before and after BAC adaptation and performing pairwise alignment, 100% identity was detected; a finding that means the absence of mutation after adaptation to BAC. Conclusion This study suggests that the widespread and increased use of biocides like BAC at sublethal concentrations has led to an increase biofilm formation by K. pneumoniae isolates. Enhanced biofilm formation could result in treatment failure of the infections generated by this pathogen.

The article presents a comparison between microbiological and high performance liquid chromatographic (HPLC) assays for quantification of moxifloxacin in tablets, ophthalmic solutions and human plasma. The microbiological method employed a cylinder-plate agar diffusion assay using a strain of Esherichia coli ATCC 25922 as the test organism and phosphate buffer (pH8) as the diluent. The calibration curves were linear (R2 > 0.98) over a concentration range of 0.125 to 16 µgml-1. The within day and between days precisions were ≤ 4.47% and ≤ 6.39% respectively. Recovery values were between 89.4 and 110.2%. The HPLC assay used Hypersil® BDS C18 reversed phase column (250×4.6 mm, 5µm) with a mobile phase comprising 20 mM ammonium dihydrogen orthophosphate (pH3) and acetonitrile (75:25) and flowing at 1.5 ml/min. The detection was at 295nm. The calibration curves were linear (R2 > 0.999) over the range of 0.125 to 16 µg ml-1. The within day and between days precisions were ≤ 4.07% and ≤ 5.09% respectively. Recovery values were between 97.7 and 107.6%. Similar potencies were obtained after the analysis of moxifloxacin tablets and ophthalmic solutions by both methods. Also pharmacokinetic parameters were calculated after the analysis of plasma samples of six male healthhy volunteers by both validated methods.

The sporicidal activity of a 1% solution of five local anaesthetics and five preservatives (cetrimide, chlorocresol, chlorhexidine, phenoxyethanol and phenylmercuric nitrate) at their commonly used concentrations, alone and in binary combinations, was determined against Bacillus subtilis and Aspergillus niger spores at different temperature levels by surface viable count technique. The sporicidal activity of all tested systems was temperature dependent and A. niger spores were much more sensitive to the effect of the test systems than B. subtilis spores. The temperatures at which 99% kill is achieved after 30 min exposure were calculated. For local anaesthetics used singly against A. niger the recorded temperatures were 30 degrees C for amethocaine, 45 degrees C for amylocaine, 43 degrees C for cincochaine, 48 degrees C and 50 degrees C for lignocaine and procaine, respectively. A control temperature of 58 degrees C for saline solution was observed. Much higher temperatures were recorded for B. subtilis spores. Cincochaine was the most effective local anaesthetic with a recorded temperature of 60 degrees C for a 99% kill while amylocaine and amethocaine showed temperatures of 84 and 90 degrees C respectively. Procaine, lignocaine as well as the control saline solution recorded temperatures higher than 100 degrees C. Among the 25 binary combinations of local anaesthetics and preservatives tested, the most pronounced potentiation of the sporicidal activity against fungal spores was recorded with chlorocresol combinations, while other combinations of the four remaining preservatives showed different types of interactions at various temperature levels.