Effects of ceragenins and conventional antimicrobials on Candida albicans and Staphylococcus aureus mono and multispecies biofilms.

It is known that synergy between Candida albicans and Staphylococcus aureus results in enhanced biofilm formation and increased resistance to antimicrobials. Ceragenins (CSAs) are derivatives of cholic acid designed to mimic the antimicrobial activities of endogenous antimicrobial peptides. In this study, various CSAs were tested on C. albicans and methicillin-susceptible S. aureus or methicillin-resistant S. aureus mono or multispecies biofilms at 2 different concentrations (16 and 64 µg/mL) and compared with conventional antimicrobials. CSA-8 was active agent both with mono and multispecies biofilms (P < 0.05). Among antifungals, amphotericin B and, among antibacterials, ciprofloxacin and gentamicin were active agents against all studied microorganisms. This study suggests that CSAs, especially CSA-8, have useful antibiofilm effects against monomicrobial or fungal-bacterial multispecies biofilms.

In vitro activities of antifungals alone and in combination with tigecycline against Candida albicans biofilms.

BACKGROUND: Candida may form biofilms, which are thought to underlie the most recalcitrant infections. METHODS: In this study, activities of antifungal agents alone and in combination with tigecycline against planktonic cells and mature and developing biofilms of Candida albicans isolates were evaluated. RESULTS: Amphotericin B and echinocandins were found to be the most effective agents against mature biofilms, whereas the least effective agent was fluconazole. Furthermore, the most effective anti-fungal monotherapies against biofilm formation were amphotericin B and anidulafungin, and the least effective monotherapy was itraconazole. The combination of tigecycline and amphotericin B yielded synergistic effects, whereas combinations containing itraconazole yielded antagonist effects against planktonic cells. The combination of tigecycline and caspofungin exhibited maximum efficacy against mature biofilms, whereas combinations containing itraconazole exhibited minimal effects. Combinations of tigecycline with amphotericin B or anidulafungin were highly effective against C. albicans biofilm formation. DISCUSSION: In summary, tigecycline was highly active against C. albicans particularly when combined with amphotericin B and echinocandins.

Antimicrobial activities of widely consumed herbal teas, alone or in combination with antibiotics: an in vitro study.

BACKGROUND: Because of increasing antibiotic resistance, herbal teas are the most popular natural alternatives for the treatment of infectious diseases, and are currently gaining more importance. We examined the antimicrobial activities of 31 herbal teas both alone and in combination with antibiotics or antifungals against some standard and clinical isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, methicillin susceptible/resistant Staphylococcus aureus and Candida albicans. METHODS: The antimicrobial activities of the teas were determined by using the disk diffusion and microbroth dilution methods, and the combination studies were examined by using the microbroth checkerboard and the time killing curve methods. RESULTS: Rosehip, rosehip bag, pomegranate blossom, thyme, wormwood, mint, echinacea bag, cinnamon, black, and green teas were active against most of the studied microorganisms. In the combination studies, we characterized all the expected effects (synergistic, additive, and antagonistic) between the teas and the antimicrobials. While synergy was observed more frequently between ampicillin, ampicillin-sulbactam, or nystatine, and the various tea combinations, most of the effects between the ciprofloxacin, erythromycin, cefuroxime, or amikacin and various tea combinations, particularly rosehip, rosehip bag, and pomegranate blossom teas, were antagonistic. The results of the time kill curve analyses showed that none of the herbal teas were bactericidal in their usage concentrations; however, in combination with antibiotics they showed some bactericidal effect. DISCUSSION: Some herbal teas, particularly rosehip and pomegranate blossom should be avoided because of their antagonistic interactions with some antibiotics during the course of antibiotic treatment or they should be consumed alone for their antimicrobial activities.

Investigation of preservative efficacy and microbiological content of some cosmetics found on the market.

In this study, microbial content and preservative efficacy of various cosmetic products, which are produced and sold in markets of our country, were investigated. Microbial content and preservative efficacies of products were investigated according to United States Pharmacopeia (USP) method. Microorganism counts of out 14 of 93 cosmetic products were recovered in the range between 1.5 x 10(2)-5.5 x 10(5) cfu/ml. Staphylococcus aureus was the most common contaminant identified in samples (from six different products) and was followed by Burkholderia cepacia (from four different products). Gram negative organisms, including Pseudomonas aeruginosa and a yeast Candida krusei, were also isolated from samples. Escherichia coli and Salmonella sp. were not recovered from any of samples. Preservative efficacies of fourteen out of ninety-three products did not meet the general efficacy of antimicrobial preservation criteria of the USP. Among these fourteen products, degradation and color change by Aspergillus niger was observed in one of samples. According to results, it was observed that pathogen and potential pathogen microorganisms can be found in unused cosmetic products and also preservatives may be ineffective in preventing them. Thus, in order to prevent the contamination that can occur during production, manufacturers are required to manufacture products in compliance with wholesome manufacturing practices and, considering consumer health, it is necessary to add an effective preservative as determined by regulations.

Postantibiotic effect of various antibiotics on Legionella pneumophila strains isolated from water systems.

The postantibiotic effects (PAE) of azithromycin, clarithromycin, ciprofloxacin, and levofloxacin were investigated against Legionella pneumophila (L. pneumophila) strains isolated from several hot water systems of different buildings in Istanbul. Each strain in logarithmic phase of growth was exposed to concentrations of antibiotics equal to minimum inhibitory concentration (MIC) and 4× MIC for 1 h. Recovery periods of test cultures were evaluated after centrifugation using the viable counting method. The mean values of PAEs for the strains of L. pneumophila, azithromycin at a concentration equal to and 4 times of MIC values were found 1.75 ± 0.28 h and 4.06 ± 0.44 h, for clarithromycin 2.98 ± 0.70 h and 4.18 ± 0.95 h, for ciprofloxacin 2.97 ± 0.63 h and 4.70 ± 0.63 h, for levofloxacin 2.05 ± 0.33 h and 3.78 ± 0.46 h, respectively. All of the antibiotics showed increased PAE values in a concentration-dependent manner. The findings of our study may play useful role in selecting the appropriate timing of doses during therapy with antimicrobials to treat patients infected with L. pneumophila.