Probing linker design in citric acid-ciprofloxacin conjugates.

A series of structurally related citric acid-ciprofloxacin conjugates was synthesised to investigate the influence of the linker between citric acid and ciprofloxacin on antibacterial activities. Minimum inhibitory concentrations (MICs) were determined against a panel of reference strains and clinical isolates of bacteria associated with infection in humans and correlated with the DNA gyrase inhibitory activity. The observed trend was rationalised by computational modelling.

Probing bacterial uptake of glycosylated ciprofloxacin conjugates.

Mono- and disaccharide-functionalised conjugates of the fluoroquinolone antibiotic ciprofloxacin have been synthesised and used as chemical probes of the bacterial uptake of glycosylated ciprofloxacin. Their antimicrobial activities against a panel of clinically relevant bacteria were determined: the ability of these conjugates to inhibit their target DNA gyrase and to be transported into the bacteria was assessed by using in vivo and in vitro assays. The data suggest a lack of active uptake through sugar transporters and that although the addition of monosaccharides is compatible with the inhibition of DNA gyrase, the addition of a disaccharide results in a significant decrease in antimicrobial activity.

Staphyloferrin A as siderophore-component in fluoroquinolone-based Trojan horse antibiotics.

A series of fluoroquinolone conjugates was synthesised by linking the carboxylic acid functionality of the carboxylate-type siderophore staphyloferrin A and its derivatives to the piperazinyl nitrogen of ciprofloxacin and norfloxacin via amide bond formation. Four siderophore-drug conjugates were screened against a panel of bacteria associated with infection in humans. Whilst no activity was found against ciprofloxacin- or norfloxacin-resistant bacteria, one of the conjugates retained antibacterial activity against fluoroquinolone-susceptible strains although the structure of its lysine-based siderophore component differs from that of the natural siderophore staphyloferrin A.

Potential for airborne transmission of infection in the waiting areas of healthcare premises: stochastic analysis using a Monte Carlo model.

Background: Although many infections that are transmissible from person to person are acquired through direct contact between individuals, a minority, notably pulmonary tuberculosis (TB), measles and influenza are known to be spread by the airborne route. Airborne infections pose a particular threat to susceptible individuals whenever they are placed together with the index case in confined spaces. With this in mind, waiting areas of healthcare facilities present a particular challenge, since large numbers of people, some of whom may have underlying conditions which predispose them to infection, congregate in such spaces and can be exposed to an individual who may be shedding potentially pathogenic microorganisms.

Effect of negative air ions on the potential for bacterial contamination of plastic medical equipment.

Background: In recent years there has been renewed interest in the use of air ionizers to control the spread of infection in hospitals and a number of researchers have investigated the biocidal action of ions in both air and nitrogen. By comparison, the physical action of air ions on bacterial dissemination and deposition has largely been ignored. However, there is clinical evidence that air ions might play an important role in preventing the transmission of Acinetobacter infection.

How does healthcare worker hand hygiene behaviour impact upon the transmission of MRSA between patients?: an analysis using a Monte Carlo model.

Background: Good hand hygiene has for many years been considered to be the most important measure that can be applied to prevent the spread of healthcare-associated infection (HAI). Continuous emphasis on this intervention has lead to the widespread opinion that HAI rates can be greatly reduced by increased hand hygiene compliance alone. However, this assumes that the effectiveness of hand hygiene is not constrained by other factors and that improved compliance in excess of a given level, in itself, will result in a commensurate reduction in the incidence of HAI.

Synthesis of citrate-ciprofloxacin conjugates.

Two regioisomeric citrate-functionalized ciprofloxacin conjugates have been synthesized and their antimicrobial activities against a panel of clinically-relevant bacteria have been determined. Cellular uptake mechanisms were investigated using wild-type and ompF deletion strains of Escherichia coli K-12.

Increasing the frequency of hand washing by healthcare workers does not lead to commensurate reductions in staphylococcal infection in a hospital ward.

Background: Hand hygiene is generally considered to be the most important measure that can be applied to prevent the spread of healthcare-associated infection (HAI). Continuous emphasis on this intervention has lead to the widespread opinion that HAI rates can be greatly reduced by increased hand hygiene compliance alone. However, this assumes that the effectiveness of hand hygiene is not constrained by other factors and that improved compliance in excess of a given level, in itself, will result in a commensurate reduction in the incidence of HAI.

The ventilation of multiple-bed hospital wards: review and analysis.

Background: Although the merits of ventilating operating theatres and isolation rooms are well known, the clinical benefits derived from ventilating hospital wards and patient rooms are unclear. This is because relatively little research work has been done in the ventilation of these areas compared with that done in operating theatres and isolation rooms. Consequently, there is a paucity of good quality data from which to make important decisions regarding hospital infrastructure.

Aerial dissemination of Clostridium difficile spores.

Background: Clostridium difficile-associated diarrhoea (CDAD) is a frequently occurring healthcare-associated infection, which is responsible for significant morbidity and mortality amongst elderly patients in healthcare facilities. Environmental contamination is known to play an important contributory role in the spread of CDAD and it is suspected that contamination might be occurring as a result of aerial dissemination of C. difficile spores.

Bactericidal action of positive and negative ions in air.

Background: In recent years there has been renewed interest in the use of air ionisers to control of the spread of airborne infection. One characteristic of air ions which has been widely reported is their apparent biocidal action. However, whilst the body of evidence suggests a biocidal effect in the presence of air ions the physical and biological mechanisms involved remain unclear.

The influence of nurse cohorting on hand hygiene effectiveness.

Background: Direct contact between health care staff and patients is generally considered to be the primary route by which most exogenously-acquired infections spread within and between wards. Handwashing is therefore perceived to be the single most important infection control measure that can be adopted, with the continuing high infection rates generally attributed to poor hand hygiene compliance.

Methods: Through the use of simple mathematical models, this paper demonstrates that under conditions of high patient occupancy or understaffing, handwashing alone is unlikely to prevent the transmission of infection.

Air ionisation and colonisation/infection with methicillin-resistant Staphylococcus aureus and Acinetobacter species in an intensive care unit.

Objective: To determine effect of negative air ions on colonisation/infection with methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter species in an intensive care unit.

Design: Prospective single-centre cross-over study in an adult general intensive care unit.

Patients: 201 patients whose stay on the unit exceeded 48 hour's duration.

Use of colony morphology to distinguish different enterococcal strains and species in mixed culture from clinical specimens.

Colony morphology on kanamycin esculin azide agar was investigated as a means of selecting different species and strains of enterococci from clinical specimens. Four representative colonies of each morphotype were indistinguishable by pulsed-field gel electrophoresis, biotype, and antibiogram analysis. The optimum time for identification of different colony morphotypes was 72 h.

Enterococcal intravascular catheter-related bloodstream infection: management and outcome of 61 consecutive cases.

Enterococci are an increasingly important cause of intravascular catheter-related bloodstream infection (CRBSI), but the evidence base for treating such cases is limited. Successful antimicrobial treatment of CRBSI while leaving the central venous catheter (CVC) in situ has been reported for some bacteria, such as coagulase-negative staphylococci, but the effectiveness of this approach for treating enterococcal CRBSI is unknown. We aimed to determine the effectiveness of treatment options for enterococcal CRBSI and whether CVC removal is mandatory.

Typing of Epidemiologically Associated Environmental and Clinical Strains of Listeria monocytogenes by Random Amplification of Polymorphic DNA.

One hundred and three strains of Listeria monocytogenes (Lm), Listeria seeligeri and Listeria innocua of clinical, food, and environmental origin were examined by generating randomly amplified polymorphic DNA (RAPD). Using one 10 bp and two 13 bp random primers, epidemiologically related strains, previously shown to be indistinguishable by phage typing, yielded identical RAPD profiles. Strains isolated from the hands of three workers in a retail food establishment showed the presence of a single predominant Lm isolate.

The Survival of Listeria monocytogenes on Fingertips and Factors Affecting Elimination of the Organism by Hand Washing and Disinfection.

The survival of Listeria monocytogenes applied to the fingertips was investigated using both an impression plate and an elution method. When suspended in saline, L. monocytogenes NCTC 9863 survived for up to 60 min on fingertips, but survival times were greatly extended when the inoculum was suspended in milk.

Incidence of Listeria spp. in Pre-cooked, Chilled Chicken Products as Determined by Culture and Enzyme-linked Immunoassay (ELISA).

One hundred and two samples of ready-to-eat, pre-cooked, chilled chicken were examined for Listeria spp. using culture and a commercially available enzyme linked immunoassay (ELISA). Overall, 29 (28%) samples contained Listeria spp.