Community dynamics and the lower airway microbiota in stable chronic obstructive pulmonary disease, smokers and healthy non-smokers.

RATIONALE: The role bacteria play in the progression of COPD has increasingly been highlighted in recent years. However, the microbial community complexity in the lower airways of patients with COPD is poorly characterised. OBJECTIVES: To compare the lower airway microbiota in patients with COPD, smokers and non-smokers. METHODS: Bronchial wash samples from adults with COPD (n=18), smokers with no airways disease (n=8) and healthy individuals (n=11) were analysed by extended-culture and culture-independent Illumina MiSeq sequencing. We determined aerobic and anaerobic microbiota load and evaluated differences in bacteria associated with the three cohorts. Culture-independent analysis was used to determine differences in microbiota between comparison groups including taxonomic richness, diversity, relative abundance, 'core' microbiota and co-occurrence. MEASUREMENT AND MAIN RESULTS: Extended-culture showed no difference in total load of aerobic and anaerobic bacteria between the three cohorts. Culture-independent analysis revealed that the prevalence of members of Pseudomonas spp. was greater in the lower airways of patients with COPD; however, the majority of the sequence reads for this taxa were attributed to three patients. Furthermore, members of Bacteroidetes, such as Prevotella spp., were observed to be greater in the 'healthy' comparison groups. Community diversity (α and ß) was significantly less in COPD compared with healthy groups. Co-occurrence of bacterial taxa and the observation of a putative 'core' community within the lower airways were also observed. CONCLUSIONS: Microbial community composition in the lower airways of patients with COPD is significantly different to that found in smokers and non-smokers, indicating that a component of the disease is associated with changes in microbiological status.

Use of culture and molecular analysis to determine the effect of antibiotic treatment on microbial community diversity and abundance during exacerbation in patients with cystic fibrosis.

BACKGROUND: Anaerobic bacteria are increasingly regarded as important in cystic fibrosis (CF) pulmonary infection. The aim of this study was to determine the effect of antibiotic treatment on aerobic and anaerobic microbial community diversity and abundance during exacerbations in patients with CF. METHODS: Sputum was collected at the start and completion of antibiotic treatment of exacerbations and when clinically stable. Bacteria were quantified and identified following culture, and community composition was also examined using culture-independent methods. RESULTS: Pseudomonas aeruginosa or Burkholderia cepacia complex were detected by culture in 24/26 samples at the start of treatment, 22/26 samples at completion of treatment and 11/13 stable samples. Anaerobic bacteria were detected in all start of treatment and stable samples and in 23/26 completion of treatment samples. Molecular analysis showed greater bacterial diversity within sputum samples than was detected by culture; there was reasonably good agreement between the methods for the presence or absence of aerobic bacteria such as P aeruginosa (κ=0.74) and B cepacia complex (κ=0.92), but agreement was poorer for anaerobes. Both methods showed that the composition of the bacterial community varied between patients but remained relatively stable in most individuals despite treatment. Bacterial abundance decreased transiently following treatment, with this effect more evident for aerobes (median decrease in total viable count 2.3×10(7) cfu/g, p=0.005) than for anaerobes (median decrease in total viable count 3×10(6) cfu/g, p=0.046). CONCLUSION: Antibiotic treatment targeted against aerobes had a minimal effect on abundance of anaerobes and community composition, with both culture and molecular detection methods required for comprehensive characterisation of the microbial community in the CF lung. Further studies are required to determine the clinical significance of and optimal treatment for these newly identified bacteria.

Antibacterial Activity of Four Plant Extracts Extracted from Traditional Chinese Medicinal Plants against Listeria monocytogenes, Escherichia coli, and Salmonella enterica subsp. enterica serovar Enteritidis.

The worldwide ethnobotanical use of four investigated plants indicates antibacterial properties. The aim of this study was to screen and determine significant antibacterial activity of four plant extracts in vitro and in a poultry digest model. Using broth microdilution, the concentrations at which four plant extracts inhibited Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli over 24 hours was determined. Agrimonia pilosa Ledeb, Iris domestica (L.) Goldblatt and Mabb, Anemone chinensis Bunge, and Smilax glabra Roxb all exhibited a minimum inhibitory concentration (MIC) of 62.5mg/L and a minimum bactericidal concentration (MBC) of 500mg/L against one pathogen. A. pilosa Ledeb was the most effective against L. monocytogenes and E. coli with the exception of S. enteritidis, for which A. chinensis Bunge was the most effective. Time-kills of A. pilosa Ledeb and A. chinensis Bunge against L. monocytogenes, E. coli and S. enteritidis incubated in poultry cecum were used to determine bactericidal activity of these plant extracts. A. chinensis Bunge, significantly reduced S. enteritidis by ≥ 99.99% within 6 hours. A. pilosa Ledeb exhibited effective significant bactericidal activity within 4 hours against L. monocytogenes and E. coli. This paper highlights the potential of these plant extracts to control pathogens commonly found in the poultry gastrointestinal tract.

Antimicrobial stewardship in care homes: outcomes of importance to stakeholders.

BACKGROUND: Heterogeneity of outcomes measured in trials to improve antimicrobial stewardship (AMS) in care homes has compromised quality of evidence. A core outcome set (COS) is needed to facilitate interpretation and synthesis of evidence in this area. AIM: To determine outcomes deemed important by relevant stakeholders for interventions aimed at improving AMS in care homes, and to produce a refined list of outcomes that could be considered for use in future research. METHODS: Semi-structured face-to-face or telephone interviews were conducted with key stakeholders. Outcomes reported in previous randomized controlled trials (RCTs) of AMS in care homes were included in a topic guide for interviews. Content analysis was undertaken to identify potential outcomes suggested by participants, followed by further review. FINDINGS: Twenty-seven outcomes reported in RCTs were refined into a list of 12 overarching outcomes. Interviews with participants (six researchers, 31 healthcare professionals, and four family members of care home residents) identified 40 additional outcomes that were important to them. From these 52 outcomes, the total number of antimicrobials, the appropriateness of antimicrobial prescribing and adherence to guidelines were highlighted by most participants. After reviewing all 52 outcomes, a refined list of 14 outcomes potentially feasible for use in AMS trials in care homes was generated. CONCLUSION: s: A number of potential outcomes for AMS in care homes, some of which had not been reported in previous studies, were identified. The refined list of 14 outcomes will be used in a future study to agree a COS for care home AMS trials.

Can the use of a rapid polymerase chain screening method decrease the incidence of nosocomial meticillin-resistant Staphylococcus aureus?

Rapid detection of MRSA may be important for the control of MRSA spread in hospitals. The aim of this investigation was to compare the use of a rapid polymerase chain reaction (PCR) screening method with standard culture for the detection of meticillin-resistant Staphylococcus aureus (MRSA) colonisation and to determine its impact on the incidence of MRSA in two hospital wards. During the first phase of the investigation (four months), patients in a surgical ward were screened using the rapid PCR technique and patients in a medical/cardiology ward were screened with standard culture methods. During the second phase of the investigation (four months), MRSA screening methods were switched between the two wards. An audit of infection control practices on each ward was made at the end of each phase in order to check whether any changes had occurred that might influence the risks of MRSA transmission. Use of the rapid PCR method significantly reduced the median time between swabs being taken, to the results being telephoned to the wards (excluding weekends), from 47 to 21 h (P<0.001). However, comparison of MRSA incidence during use of PCR (20/1000 bed-days) and culture methods (22.1/1000 bed-days) revealed no significant difference in incidence on the surgical ward (P=0.69). Regarding the medical/cardiology ward, analysis of data was complicated by an increase in the detection of MRSA during the PCR phase (P<0.05). The study demonstrated that rapid PCR can significantly reduce the turnaround times but reducing the time between swabs being taken to results being telephoned to the ward is still not sufficient to limit the transmission of MRSA.

Infection control strategies for preventing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in nursing homes for older people.

BACKGROUND: Nursing homes for older people provide an environment likely to promote the acquisition and spread of meticillin-resistant Staphylococcus aureus (MRSA), putting residents at increased risk of colonisation and infection. It is recognised that infection control strategies are important in preventing and controlling MRSA transmission. OBJECTIVES: The objective of this review was to determine the effects of infection control strategies for preventing the transmission of MRSA in nursing homes for older people. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2007, Issue 1), the Cochrane Wounds Group Specialised Register (searched April 2007); the Infectious Diseases Group and EPOC also searched their Specialised Registers for this review (both May 2006). We also searched MEDLINE (from 1966 to March Week 3 2007), EMBASE (1980 to 2007 Week 13), CINAHL (1982 to March Week 3 2007), British Nursing Index (1985 to March 2007), DARE (1992 to March 2007), Web of Science (1981 to March 2007), and the Health Technology Assessment (HTA) database (1988 to March 2007). Research in progress was identified through the National Research Register, Current Clinical Trials (www.controlled-trials.com), Medical Research Council Register, Current Research in Britain (CRIB), and HSRPRoj (current USA projects). SIGLE was also searched in order to identify atypical material which was not accessible through more conventional sources. SELECTION CRITERIA: All randomised and controlled clinical trials, controlled before and after studies and interrupted time series studies of infection control interventions in nursing homes for older people were eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two authors independently reviewed the results of the searches. MAIN RESULTS: Since no studies met the selection criteria, neither a meta-analysis nor a narrative description of studies was possible. AUTHORS' CONCLUSIONS: The lack of studies in this field is surprising. Nursing homes for older people provide an environment likely to promote the acquisition and spread of infection, with observational studies repeatedly reporting that being a resident of a nursing home increases the risk of MRSA colonisation. Much of the evidence for recently-issued United Kingdom guidelines for the control and prevention of MRSA in health care facilities was generated in the acute care setting. It may not be possible to transfer such strategies directly to the nursing home environment, which serves as both a healthcare setting and a resident's home. Rigorous studies should be conducted in nursing homes, to test interventions that have been specifically designed for this unique environment.

Comparison of the cidal activity of tea tree oil and terpinen-4-ol against clinical bacterial skin isolates and human fibroblast cells.

AIMS: The aim of this study was to compare both the antimicrobial activity of terpinen-4-ol and tea tree oil (TTO) against clinical skin isolates of meticillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) and their toxicity against human fibroblast cells. METHODS AND RESULTS: Antimicrobial activity was compared by using broth microdilution and quantitative in vitro time-kill test methods. Terpinen-4-ol exhibited significantly greater bacteriostatic and bactericidal activity, as measured by minimum inhibitory and bactericidal concentrations, respectively, than TTO against both MRSA and CoNS isolates. Although not statistically significant, time-kill studies also clearly showed that terpinen-4-ol exhibited greater antimicrobial activity than TTO. Comparison of the toxicity of terpinen-4-ol and TTO against human fibroblasts revealed that neither agent, at the concentrations tested, were toxic over the 24-h test period. CONCLUSIONS: Terpinen-4-ol is a more potent antibacterial agent against MRSA and CoNS isolates than TTO with neither agent exhibiting toxicity to fibroblast cells at the concentrations tested. SIGNIFICANCE AND IMPACT OF THE STUDY: Terpinen-4-ol should be considered for inclusion as a single agent in products formulated for topical treatment of MRSA infection. However, further work would initially be required to ensure that resistance would not develop with the use of terpinen-4-ol as a single agent.

Biofilm formation by bacteria isolated from retrieved failed prosthetic hip implants in an in vitro model of hip arthroplasty antibiotic prophylaxis.

Bacterial infection primarily with Staphylococcus spp. and Propionibacterium acnes remains a significant complication following total hip replacement. In this in vitro study, we investigated the efficacy of gentamicin loading of bone cement and pre- and postoperative administration of cefuroxime in the prevention of biofilm formation by clinical isolates. High and low initial inocula, representative of the number of bacteria that may be present at the operative site as a result of overt infection and skin contamination, respectively, were used. When a high initial inoculum was used, gentamicin loading of the cement did not prevent biofilm formation by the 10 Staphylococcus spp. and the 10 P. acnes isolates tested. Similarly, the use of cefuroxime in the fluid phase with gentamicin-loaded cement did not prevent biofilm formation by four Staphylococcus spp. and four P. acnes isolates tested. However, when a low bacterial inoculum was used, a combination of both gentamicin-loaded cement and cefuroxime prevented biofilm formation by these eight isolates. Our results indicate that this antibiotic combination may protect against infection after intra-operative challenge with bacteria present in low numbers as a result of contamination from the skin but would not protect against bacteria present in high numbers as a result of overt infection of an existing implant.

Sputum antibiotic concentrations: implications for treatment of cystic fibrosis lung infection.

BACKGROUND: The success of antibiotic therapy may be predicted based on the achievement of pharmacodynamic indices (PDIs), which are determined by the susceptibility of the infecting bacteria and the concentrations of antibiotics achieved at the site of infection. The aim of this study was to determine whether PDIs associated with clinical effectiveness for ceftazidime and tobramycin were achieved at the site of infection in the lungs of cystic fibrosis (CF) patients following intravenous administration during treatment of an acute exacerbation. METHODS: Serum and sputum samples were collected from 14 CF patients and the concentration of both antibiotics in the samples determined. The susceptibility of bacteria cultured from sputum samples to both antibiotics alone and in combination was also determined. RESULTS: A total of 22 Pseudomonas aeruginosa isolates and 4 Burkholderia cepacia complex isolates were cultured from sputum samples with 55% and 4% of isolates susceptible to ceftazidime and tobramycin, respectively. Target PDIs for ceftazidime and tobramycin, an AUC/MIC ratio of 100 and a C(max)/MIC ratio of 10, respectively, were not achieved in serum or sputum simultaneously or even individually for any patient. Although the combination of ceftazidime and tobramycin was synergistic against 20 of the 26 isolates cultured, the concentrations of both antibiotics required for synergy were achieved simultaneously in only 38% of serum and 14% of sputum samples. CONCLUSION: Key PDIs associated with clinical effectiveness for ceftazidime and tobramycin were not achieved at the site of infection in the lungs of CF patients.

Effect of pH on the antimicrobial susceptibility of planktonic and biofilm-grown clinical Pseudomonas aeruginosa isolates.

The pH at the site of infection is one of a number of factors that may significantly influence the in vivo activity of an antibiotic prescribed for treatment of infection and it may be of particular importance in the treatment of cystic fibrosis (CF) pulmonary infection, as acidification of the airways in CF patients has been reported. As Pseudomonas aeruginosa is the most frequent causative pathogen of CF pulmonary infection, this study determines the effect that growth at a reduced pH, as may be experienced by P. aeruginosa during infection of the CF lung, has on the susceptibility of clinical P. aeruginosa isolates, grown planktonically and as biofilms, to tobramycin and ceftazidime. Time-kill assays revealed a clear loss of tobramycin bactericidal activity when the isolates were grown under acidic conditions. MIC and MBC determinations also showed decreased tobramycin activity under acidic conditions, but this effect was not observed for all isolates tested. In contrast, growth of the isolates at a reduced pH had no adverse effect on the bacteriostatic and bactericidal activity of ceftazidime. When the isolates were grown as biofilms, the pH at which the biofilms were formed did not affect the bactericidal activity of either tobramycin or ceftazidime, with neither antibiotic capable of eradicating biofilms formed by the isolates at each pH. This was in spite of the fact that the concentrations of both antibiotics used were much higher than the concentrations required to kill the isolates growing planktonically. These results show that growth in an acidic environment may reduce the susceptibility of clinical P. aeruginosa isolates to tobramycin.

Evidence of persistence of Prevotella spp. in the cystic fibrosis lung.

Purpose. Prevotella spp. represent a diverse genus of bacteria, frequently identified by both culture and molecular methods in the lungs of patients with chronic respiratory infection. However, their role in the pathogenesis of chronic lung infection is unclear; therefore, a more complete understanding of their molecular epidemiology is required.Methodology. Pulsed Field Gel Electrophoresis (PFGE) and Random Amplified Polymorphic DNA (RAPD) assays were developed and used to determine the degree of similarity between sequential isolates (n=42) from cystic fibrosis (CF) patients during periods of clinical stability and exacerbation.Results. A wide diversity of PFGE and RAPD banding patterns were observed, demonstrating considerable within-genus heterogeneity. In 8/12 (66.7 %) cases, where the same species was identified at sequential time points, pre- and post-antibiotic treatment of an exacerbation, PFGE/RAPD profiles were highly similar or identical. Congruence was observed between PFGE and RAPD (adjusted Rand coefficient, 0.200; adjusted Wallace RAPD->PFGE 0.459, PFGE->RAPD 0.128). Furthermore, some isolates could not be adequately assigned a species name on the basis of 16S rRNA analysis: these isolates had identical PFGE/RAPD profiles to Prevotella histicola.Conclusion. The similarity in PFGE and RAPD banding patterns observed in sequential CF Prevotella isolates may be indicative of the persistence of this genus in the CF lung. Further work is required to determine the clinical significance of this finding, and to more accurately distinguish differences in pathogenicity between species.

Evaluation of a poly(vinyl pyrollidone)-coated biomaterial for urological use.

The associated problems of bacterial biofilm formation and encrustation that may cause obstruction or blockage of urethral catheters and ureteral stents often hinders the effective use of biomaterials within the urinary tract. In this in vitro study, we have investigated the surface properties of a hydrophilic poly(vinyl pyrollidone) (PVP)-coating applied to polyurethane and determined its suitability for use as a urinary tract biomaterial by comparing its lubricity and ability to resist bacterial adherence and encrustation with that of uncoated polyurethane and silicone. The PVP-coated polyurethane was significantly more hydrophilic and more lubricious than either uncoated polyurethane or silicone. Adherence of a hydrophilic Escherichia coli isolate to PVP-coated polyurethane and uncoated polyurethane was similar but significantly less than adherence to silicone. Adherence of a hydrophobic Enterococcus faecalis isolate to PVP-coated polyurethane and silicone was similar but was significantly less than adherence to uncoated polyurethane. Struvite encrustation was similar on the PVP-coated polyurethane and silicone but significantly less than on uncoated polyurethane. Furthermore, hydroxyapatite encrustation was significantly less on the PVP-coated polyurethane than on either uncoated polyurethane or silicone. The results suggest that the PVP-coating could be useful in preventing complications caused by bacterial biofilm formation and the deposition of encrustation on biomaterials implanted in the urinary tract and, therefore, warrants further evaluation.

Development of a model for assessment of biomaterial encrustation in the upper urinary tract.

A need exists for ureteral stent materials capable of preventing or reducing encrustation. The aim of this study, therefore, was to develop an in vitro model producing biomaterial encrustation similar to that on stents in vivo. Three models were designed and evaluated. Polyurethane stent sections were immersed in human urine (37 degrees C, 5% CO2): (1) with and (2) without crushed human kidney stone and (3) in an artificial urine (37 degrees C, 5% CO2). Encrustation of similar composition, as determined by infrared spectroscopy, X-ray diffraction and energy dispersive X-ray analysis, formed on stent materials in vivo, in artificial urine and in human urine with crushed kidney stone. Magnesium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite) predominated in all encrustations. The reproducibility and ease of use of the artificial urine model provided optimum encrustation assessment of materials presently used in ureteral stents and evaluation of novel biomaterials.

Comparative assessment of ureteral stent biomaterial encrustation.

Long-term use of ureteral stents is hindered by the inherent problem of biomaterial encrustation which may lead to stone formation and attendant problems. The wide variety of polymeric biomaterials currently used for stent fabrication suggests that no single material is significantly superior to the others at resisting encrustation. A model representing upper urinary tract conditions was employed to compare the long-term struvite and hydroxyapatite encrustation of five materials currently used in the fabrication of ureteral stents. Silicone was least prone to struvite encrustation, followed by polyurethane, silitek, percuflex and hydrogel-coated polyurethane, in rank order. Similarly, silicone was least prone to hydroxyapatite encrustation, followed by silitek, polyurethane, percuflex and hydrogel-coated polyurethane. This study has shown that the problem of encrustation may limit the long-term use of ureteral stent biomaterials and suggests directions for improvement of biomaterials in this regard.

Improved detection of infection in hip replacements. A currently underestimated problem.

Our aim was to determine if the detection rate of infection of total hip replacements could be improved by examining the removed prostheses. Immediate transfer of prostheses to an anaerobic atmosphere, followed by mild ultrasonication to dislodge adherent bacteria, resulted in the culture of quantifiable numbers of bacteria, from 26 of the 120 implants examined. The same bacterial species were cultured by routine microbiological techniques from only five corresponding tissue samples. Tissue removed from 18 of the culture-positive implants was suitable for quantitative tissue pathology and inflammatory cells were present in all samples. Furthermore, inflammatory cells were present in 87% of tissue samples taken from patients whose implants were culture-negative. This suggests that these implants may have been infected by bacteria which were not isolated by the techniques of culture used. The increased detection of bacteria from prostheses by culture has improved postoperative antibiotic therapy and should reduce the need for further revision.

Assessment of encrustation behaviour on urinary tract biomaterials.

The effective clinical use of biomaterials within the urinary tract is often hindered by the associated problems of bacterial biofilm formation and encrustation which may cause obstruction or blockage of urethral catheters and ureteral stents. Methods for assessing encrustation formation on these devices are reviewed and novel urinary tract biomaterials which may be more effective at resisting encrustation are discussed.

Inflammatory and immunological biomarkers are not related to survival in adults with Cystic Fibrosis.

BACKGROUND: Chronic Pseudomonas aeruginosa pulmonary infection is associated with a decline in lung function and reduced survival in people with Cystic Fibrosis (CF). Damaging inflammatory and immunological mediators released in the lungs can be used as markers of chronic infection, inflammation and lung tissue damage. METHODS: Clinical samples were collected from CF patients and healthy controls. Serum IgG and IgA anti-Pseudomonas antibodies, sputum IL-8 and TNFα, plasma IL-6 and urine TNFr1 were measured by ELISA. Sputum neutrophil elastase (NE), cathepsin S and cathepsin B were measured by spectrophotometric and fluorogenic assays. The relationship between IgG and IgA, inflammatory mediators and long-term survival was determined. RESULTS: IgG and IL-6 positively correlated with mortality. However, multivariate analysis demonstrated that after adjusting for FEV(1), IgG was not independently related to mortality. A relationship was observed between IgG and IL-6, TNFα, TNFr1 and between IgA and IL8, cathepsin S and cathepsin B. CONCLUSIONS: These data indicate that biomarkers of inflammation are not independent predictors of survival in people with CF.

Efficacy of a standard methicillin-resistant Staphylococcus aureus decolonisation protocol in routine clinical practice.

Decolonisation may reduce the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection in individual carriers and prevent transmission to other patients. The aims of this prospective cohort study were to determine the long-term efficacy of a standardised decolonisation regimen and to identify factors associated with failure. Patients colonised with MRSA underwent decolonisation, which was considered to be successful if there was no growth in three consecutive sets of site-specific screening swabs obtained weekly post treatment. If patients were successfully decolonised, follow-up cultures were performed 6 and 12 months later. Of 137 patients enrolled, 79 (58%) were successfully decolonised. Of these 79, 53 (67%) and 44 (56%) remained decolonised at 6 and 12 months respectively. Therefore only 44/137 (32%) patients who completed decolonisation were MRSA negative 12 months later. Outcome was not associated with a particular strain of MRSA. Successful decolonisation was less likely in patients colonised with a mupirocin-resistant isolate (adjusted odds ratio: 0.08; 95% confidence interval: 0.02-0.30), in patients with throat colonisation (0.22; 0.07-0.68) and in patients aged >80 years (0.30; 0.10-0.93) compared with those aged 60-80 years. These findings suggest that although initially successful in some cases, the protocol used did not result in long-term clearance of MRSA carriage for most patients.