Effects of some tricyclic psychopharmacons and structurally related compounds on motility ofProteus vulgaris

Do phenothiazines possess antimicrobial and efflux inhibitory properties?

Antibiotic resistance is a global health concern; the rise of drug-resistant bacterial infections is compromising the medical advances that resulted from the introduction of antibiotics at the beginning of the 20th century. Considering that the presence of mutations within individuals in a bacterial population may allow a subsection to survive and propagate in response to selective pressure, as long as antibiotics are used in the treatment of bacterial infections, development of resistance is an inevitable evolutionary outcome. This, combined with the lack of novel antibiotics being released to the clinical market, means the need to develop alternative strategies to treat these resistant infections is critical. We discuss how the use of antibiotic adjuvants can minimise the appearance and impact of resistance. To this effect, several phenothiazine-derived drugs have been shown to potentiate the activities of antibiotics used to treat infections caused by Gram-positive and Gram-negative bacteria. Outside of their role as antipsychotic medications, we review the evidence to suggest that phenothiazines possess inherent antibacterial and efflux inhibitory properties enabling them to potentially combat drug resistance. We also discuss that understanding their mode of action is essential to facilitate the design of new phenothiazine derivatives or novel agents for use as antibiotic adjuvants.

Inhibitors of Bacterial Swarming Behavior

Bacteria can migrate in groups of flagella-driven cells over semisolid surfaces. This coordinated form of motility is called swarming behavior. Swarming is associated with enhanced virulence and antibiotic resistance of various human pathogens and may be considered as favorable adaptation to the diverse challenges that microbes face in rapidly changing environments. Consequently, the differentiation of motile swarmer cells is tightly regulated and involves multi-layered signaling networks. Controlling swarming behavior is of major interest for the development of novel anti-infective strategies. In addition, compounds that block swarming represent important tools for more detailed insights into the molecular mechanisms of the coordination of bacterial population behavior. Over the past decades, there has been major progress in the discovery of small-molecule modulators and mechanisms that allow selective inhibition of swarming behavior. Herein, an overview of the achievements in the field and future directions and challenges will be presented.

Treatment of infectious disease: beyond antibiotics

Several antibiotics have been discovered following the discovery of penicillin. These antibiotics had been helpful in treatment of infectious diseases considered dread for centuries. The advent of multiple drug resistance in microbes has posed new challenge to researchers. The scientists are now evaluating alternatives for combating infectious diseases. This review focuses on major alternatives to antibiotics on which preliminary work had been carried out. These promising anti-microbial include: phages, bacteriocins, killing factors, antibacterial activities of non-antibiotic drugs and quorum quenching.

The antimotility action of a trifluoromethyl ketone on some gram-negative bacteria

The inhibition of bacterial motility was studied by a trifluoro methyl ketone derivative on two Escherichia coli strains (wild strain having a proton pump system and the proton pump-deficient mutant strain) and two Helicobacter pylori strains (clarithromycin susceptible and clarithromycin resistant). Evidence is presented of the inhibitory action of 1-(2-benzoxazolyl)-3,3,3-trifluoro-2-propanone (TF18) on the proton motive forces of the two bacterial strains by affecting the action of biological motor and proton efflux in the membranes. The swimming, the forward motion was more sensitive than the vibration or tumbling to the inhibition. We suppose that the inhibiton of bacterial motility is related to the virulence of bacteria: consequently the pathogenicity can be reduced in the presence of TF18.

Effects of Trifluoromethyl Ketones on the Motility of Proteus vulgaris

In the present study, we showed the inhibition of motility by trifluoromethyl ketone (TF) derivatives (1-8) in Proteus vulgaris (P. vulgaris) cultures. Among them, 1-(2-benzoxazoyl)-3,3,3-trifluoro-2-propanone (1) showed a much stronger inhibitory effect on the motility of P. vulgaris than other TF compounds at 10% MIC. Our results suggest the possibility of an inhibitory action of TF compounds on the proton motive forces by affecting the action of biological motor and proton efflux in the membranes, resulting in a reduction of the ratio of running and the increased number of tumbling and non-motile cells.

Phenothiazines: potential management of Creutzfeldt-Jacob disease and its variants

Creutzfeldt-Jakob disease acquired from bovines (nvCJD) has been responsible for nearly 100 deaths in the UK and thousands more may die in the years to come. New variant CJD (nvCJD) is incurable and although clinical diagnosis is becoming more precise, the diagnosis is only certain at autopsy. Phenothiazine derivatives inhibit production of prions, the disease causing agent, in cultured neuroblastoma cells, and an advanced case of nvCJD was recently brought to remission by the use of these agents in combination with an antimalarial. In this review we present direct and circumstantial evidence in support of a model describing the manner by which the intracellular antimicrobial activity of phenothiazines might cause the destruction of intracellular prions.

Effect of some psychotropic drugs and a barbiturate on mycoplasmas

The inhibitory effect of selected membrane stabilisers on Mycoplasma pneumoniae, M. hominis and Ureaplasma urealyticum was investigated in vitro. The phenothiazine chlorpromazine (CPZ) and the barbiturate thiopental (Leopental(R)) as well as the stereo-isomeric thioxanthene derivatives; cis(Z)-clopenthixol (Zu-clopenthixol(R))/ trans (E)-clopenthixol and cis (Z)-chlorprothixen (Truxal(R))/trans(E)-chlorprothixen, all have antimycoplasmal effect in the range 3.9-312 mg/l, measured as growth inhibition. It was also demonstrated that the enzymatic functions of the different mycoplasma strains, such as breakdown of glucose, arginine and urea, were abolished by concentrations of CPZ that were sufficiently low to allow multiplication of the organisms. A similar effect was obtained with Leopental(R) although the mycoplasmas were generally only half as sensitive to this drug. Also M. gallisepticum and Acholeplasma laidlawii were inhibited by CPZ and Thiopental. The four thioxanthenes were all inhibitory to mycoplasmal growth and the effect was independent of their stereo-isomeric configuration. The clopenthixol stereoisomers, but not the chlorprothixene isomers, inhibited colour change at concentrations lower than those which inhibited growth. While enzyme activity may continue for some time in vitro when classic antibiotics have inhibited mycoplasmal growth, the reverse effect was observed with phenothiazines and thioxanthenes. The membrane stabilisers may be useful tools in the investigation of microbiological activity on the mycoplasma membrane. From these drugs, new 'antibiotics' might be developed with another action than that of the known antimycoplasmal drugs.