Probiotics and prebiotics in the elderly.

Probiotics (usually lactobacilli and bifidobacteria) and prebiotics (non-digestible oligosaccharides) have been shown to be useful in preventing certain disease conditions as well as possibly promoting specific aspects of health. In the present review, the evidence from clinical trials for benefits from probiotics and prebiotics to elderly populations is presented and discussed, specifically in respect of three common conditions found in the elderly. Both probiotics and prebiotics may be helpful in malnutrition, particularly in lactose intolerance and calcium absorption, and in constipation. Probiotics have been shown clearly to boost immunity in the elderly, but the clinical significance of this remains to be clarified. These results are encouraging, and further large scale studies seem justified to establish the place of probiotic and prebiotic supplements in elderly subjects.

Antibiotic resistance from two perspectives: man and microbe.

Despite much effort, antibiotic resistance continues to increase. Looking back, it is clear that this was an inevitable consequence of antibiotic use. From a bacterial viewpoint, the introduction of antibiotics was a tremendous stimulus to evolution. As a survival reaction to stress (selection pressure) bacteria, by means of their extreme biochemical and genetic versatility, have adapted to 21st Century conditions. Resistance can be to some extent contained by less and better use of antibiotics, but ultimately novel approaches to the treatment and prevention of infectious diseases will have to be forthcoming. This will only be achieved if best use is made of alternative resources presently available and most importantly, man's ingenuity must be fully engaged.

Anti-cariogenic properties of tea (Camellia sinensis).

Various components in green and black tea, the beverages made by infusing appropriately processed dried leaves of Camellia sinensis, notably simple catechins, have properties in vitro that suggest an anti-cariogenic activity. These include: a direct bactericidal effect against Streptococcus mutans and S. sobrinus; prevention of bacterial adherence to teeth; inhibition of glucosyl transferase, thus limiting the biosynthesis of sticky glucan; inhibition of human and bacterial amylases. Studies in animal models show that these in-vitro effects can translate into caries prevention. A limited number of clinical trials in man suggest that regular tea drinking may reduce the incidence and severity of caries. If substantiated, this could offer a very economical public health intervention.

Public health issues arising from microbiological and labelling quality of foods and supplements containing probiotic microorganisms.

OBJECTIVE: To assess the accuracy and helpfulness of labelling on products containing probiotic bacteria. DESIGN AND SETTING: 52 such products - 44 from the UK (21 supplements, 15 fermented functional foods, eight 'health-care' products) and eight from continental Europe - have been tested for microbiological content, and results compared to the information available on their labels. Products were stored in the dark at 4 degrees C and analysed before their expiry or sell-by date. Careful note was taken of wording on labels, package inserts, packaging, promotional literature and catalogue descriptions, as applicable. Products were cultured on appropriate bacteriological media, and organisms grown were counted and identified. RESULTS: Bioyoghurts gave no indication of numbers, and only five accurately described their bacterial content; results of culture were usually satisfactory. 'Healthcare' products (mostly intended for the bowel) usually indicated the presence of bacteria, but the numerical content was hard to ascertain, and cultural results fell short of label claims. Supplements were sometimes incorrectly labelled in bacteriological terms, and often contained markedly reduced numbers and/or had extraneous strains and/or strains specified on the label were missing. Products from continental Europe (that were sold for specific medical indications) seemed of a higher microbiological standard. The potential pathogen Enterococcus faecium was found in nine products. The most successful of the new functional foods in Britain now contain probiotics, and probiotic preparations are prominent among the expanding range of nutritional supplements presently available to consumers. CONCLUSIONS: Our findings have public health implications, and suggest that improvements are needed in labelling and quality assurance procedures for products containing probiotic organisms. The presence of the potential pathogen Enterococcus faecium (intentionally or as a contaminant) in some products calls for a review of the value of this species as a probiotic.

Cefaclor into the millennium.

We review the discovery and development of the cephalosporins and subsequently cefaclor. Cefaclor is active against a wide range of commonly encountered bacterial pathogens, acting by inhibiting cell wall synthesis. Its in vitro activity compares favourably with other beta-lactam antibiotics. Its pharmacokinetic properties indicate that an 8-hourly dosing schedule is appropriate. In addition a delayed release formulation allowing twice daily dosage has been developed. The efficacy of both formulations of cefaclor has been verified by many clinical trials. Cefaclor has been widely used in infections of the respiratory tract (including otitis media), urinary tract and soft tissues. The results of therapy are summarized. The low incidence of adverse events is highlighted and the beneficial influence of this on compliance is described. Finally, the pharmaco-economics of cefaclor are considered.

Disorganization of cell division of methicillin-resistant Staphylococcus aureus by a component of tea (Camellia sinensis): a study by electron microscopy.

A component of aqueous extracts of green tea (Camellia sinensis), known to reverse methicillin-resistance in staphylococci, causes extensive morphological changes in methicillin-resistant but not in methicillin-sensitive Staphylococcus aureus. Clumps of partly divided cocci, consisting of up to 14 individuals, with thickened internal but normal external cell walls were seen by electron microscopy in cultures of methicillin-resistant S. aureus grown in the presence of the active principle. The morphological changes observed were consistent with selective inhibition of penicillin-binding proteins.

A pilot study of Salix SST (saliva-stimulating lozenges) in post-irradiation xerostomia.

Relief from the effects of radiation-induced xerostomia resulting from use of saliva-stimulating lozenges (Salix) has been subjectively evaluated. Ten patients took Salix as required for 7 days; and self-assessed using analogue scales before and after treatment. There was a marked and statistically significant improvement in the dryness and general comfort of the mouth, and beneficial effects on eating, sleeping and speech.

The effect of a component of tea (Camellia sinensis) on methicillin resistance, PBP2' synthesis, and beta-lactamase production in Staphylococcus aureus.

Extracts of tea (Camellia sinensis) can reverse methicillin resistance in methicillin-resistant Staphylococcus aureus (MRSA) and also, to some extent, penicillin resistance in beta-lactamase-producing S. aureus. These phenomena are explained by prevention of PBP2' synthesis and inhibition of secretion of beta-lactamase, respectively. Synergy between beta-lactams and tea extracts were demonstrated by disc diffusion, chequerboard titration and growth curves. Partition chromatography of an extract of green tea on Sephadex LH-20 yielded several fractions, one of which contained a virtually pure compound that showed the above-mentioned activities, at concentrations above about 2 mg/L. The observed activities are novel and distinct from the previously reported direct antibacterial activity of tea extracts. Prevention of PBP2' synthesis offers an interesting possible new approach for the treatment of infections caused by MRSA.

Microbiological activity of whole and fractionated crude extracts of tea (Camellia sinensis), and of tea components.

Aqueous extracts of teas (Camellia sinensis) of different types and from various sources inhibited a wide range of pathogenic bacteria, including methicillin-resistant Staphylococcus aureus. Tea extracts were bactericidal to staphylococci and Yersinia enterocolitica at well below 'cup of tea' concentrations. Activity was confined to one of four fractions obtained from a green tea extract by partition chromatography. Testing of pure tea compounds and closely related chemicals suggested that the antibacterial activity of extracts of green tea can be explained by its content of epigallocatechin, epigallocatechin gallate and epicatechin gallate. In black tea extracts, theaflavin and its gallates are additional antibacterially active components.

Limitations of and indications for the use of co-trimoxazole.

Co-trimoxazole is still widely used for indications where trimethoprim alone is equally effective. Microbiological and pharmacokinetic considerations reveal that trimethoprim alone provides adequate anti-microbial activity for treatment of conditions for which co-trimoxazole is often given. Synergy may be shown in vitro, but in clinical practice is an unusual occurrence. There is no evidence from clinical studies that the sulphonamide moiety fo co-trimoxazole prevents the development of resistance to trimethoprim. The adverse event profile of co-trimoxazole is a summation of that of sulphonamide and of trimethoprim. Thus, using trimethoprim alone should reduce both the incidence and potential severity of adverse events seen when co-trimoxazole is used. Clinical trials have shown trimethoprim to be as effective as co-trimoxazole in many of the common bacterial infections of the urinary and respiratory tracts. However, there are a few specific varieties of infection for which co-trimoxazole can be shown to be superior to trimethoprim: these include toxoplasmosis, brucellosis, nocardiosis, chancroid and pneumonia caused by Pneumocystis carinii. For many common infections, scientific, rational, economic and clinical reasons dictate that trimethoprim is preferable to co-trimoxazole.

Comparative trials of cefaclor AF in uncomplicated cystitis and asymptomatic bacteriuria.

Two different doses of cefaclor advanced formulation (AF), a new sustained-release formulation of cefaclor, were compared with the regular formulation of cefaclor for efficacy and safety in the treatment of uncomplicated cystitis and asymptomatic bacteriuria. A 7-day course of treatment was used, and the trials were double-dummy and double-blind. In one trial, cefaclor AF 500 mg once daily (at night) was compared with cefaclor 250 mg three times a day. Satisfactory clinical and bacteriological responses were found in 179/189 (94.7%) and 160/191 (83.8%) patients, respectively, given cefaclor AF and in 82/87 (94.3%) and 74/90 (82.2%) patients given cefaclor, 5-9 days after the end of treatment. In the other trial, cefaclor AF 375 mg twice daily was compared with cefaclor 250 mg three times a day. Satisfactory clinical and bacteriological responses were obtained in 164/180 (91.1%) and 156/184 (84.8%) patients, respectively, given cefaclor AF, and in 86/92 (93.5%) and 81/93 (87.1%) patients taking cefaclor, 5-9 days after the end of treatment. Very similar results were found in both studies in those patients who were assessable 3-5 weeks later. Only 4.3% and 2.4% of patients treated with cefaclor AF (375 mg and 500 mg, respectively) and 2.2% of cefaclor patients discontinued therapy due to adverse events. The three most commonly reported events were vaginal moniliasis or vaginitis (8.6%), headache (5.0%) and nausea (4.8%). No significant differences were found between clinical efficacy and safety parameters in the different study groups, and it was concluded that cefaclor AF in a twice-daily or once-daily dosage is as effective and as safe as the currently recommened three-times-a-day dosage of cefaclor.

The changing face of chemotherapy.

The historical development of antibiotics has been summarized. Three distinct phases are discernible. The first (from historical times to about 1900) involved mostly folk remedies. The second (1900-c. 1940) was ushered in by Paul Ehrlich's development of the concept of 'selective toxicity' and saw the establishment of arsenicals and sulphonamides. The third, lasting to the present day, started with the exploitation of the pioneering studies of Fleming, Dubos and Waksman on antibiotic production by soil fungi. This latest phase has continued with the improvement of natural products by the skills of the medicinal chemist. The properties and evolution of three major groups of antibiotics, penicillins, cephalosporins and aminoglycosides are fully described. Finally, pathways of possible future evolution of antibiotics are outlined.

Successful use of reduced dosage of cinoxacin in the treatment of recurrent urinary infection.

Ninety-seven patients with a history of recurrent bacteriuria were treated with cinoxacin in a dosage of either 250 mg (48 patients) or 500 mg (49 patients) 12-hourly for seven days. Both regimens had a success rate in excess of 85% one week after the end of treatment, and only 15% of the patients rendered abacteriuric had relapsed four weeks later. Both dosage regimens of cinoxacin were very well tolerated. Our results show that in patients with recurrent urinary infections the conventional dosage of cinoxacin (500 mg) can be reduced to 250 mg 12-hourly without any loss of efficacy. Consequently patients seen in family practice with uncomplicated lower tract urinary infection can confidently be expected to respond equally well to a dose of 250 mg 12-hourly with the obvious advantages of less toxicity, less chance of producing resistance in the bowel flora and lower cost.