Medical device-associated infections in the long-term care setting

Metabolic interplay between Proteus mirabilis and Enterococcus faecalis facilitates polymicrobial biofilm formation and invasive disease

Polymicrobial biofilms play an important role in the development and pathogenesis of CAUTI. Proteus mirabilis and Enterococcus faecalis are common CAUTI pathogens that persistently co-colonize the catheterized urinary tract and form biofilms with increased biomass and antibiotic resistance. In this study, we uncover the metabolic interplay that drives biofilm enhancement and examine the contribution to CAUTI severity. Through compositional and proteomic biofilm analyses, we determined that the increase in biofilm biomass stems from an increase in the protein fraction of the polymicrobial biofilm matrix. We further observed an enrichment in proteins associated with ornithine and arginine metabolism in polymicrobial biofilms compared to single-species biofilms. We show that L-ornithine secretion by E. faecalis promotes arginine biosynthesis in P. mirabilis, and that disruption of this metabolic interplay abrogates the biofilm enhancement we see in vitro and leads to significant decreases in infection severity and dissemination in a murine CAUTI model.

Prevalence of healthcare-associated infections in Dutch long-term care facilities from 2009 to 2019

OBJECTIVE

We assessed trends in the prevalence of healthcare-associated infections (HCAIs) and associated resident and facility characteristics in a national network of long-term care facilities (LTCFs) in the Netherlands from 2009 to 2019.

METHODS

Participating LTCFs registered the prevalence of urinary tract infection (UTI), lower respiratory tract infection (LRTI), gastrointestinal infection (GI), bacterial conjunctivitis, sepsis and skin infection, using standardized definitions, in biannual point-prevalence surveys (PPSs). In addition, resident and LTCF characteristics were collected. Multi-level analyses were performed to study changes in the HCAI prevalence over time and to identify resident and LTCF-related risk factors. Analyses were performed for HCAIs overall and for UTI, LRTI and GI combined as these were recorded throughout the period.

RESULTS

Overall, 1353 HCAIs were registered in 44,551 residents with a prevalence of 3.0% (95% confidence interval: 2.8-3.1; range between years 2.3-5.1%). When including only UTI, LRTI and GI the prevalence decreased from 5.0% in 2009 to 2.1% in 2019. Multi-variable regression analyses for UTI, LRTI and GI combined indicated that both prolonged participation and calendar time were independently associated with HCAI prevalence; in LTCFs that participated ≥4 years, the HCAI risk was decreased (OR 0.72 (0.57-0.92)) compared with the first year, and the OR per calendar year was 0.93 (0.88-0.97).

CONCLUSIONS

Over 11 years of PPS in LTCFs the HCAI prevalence decreased over time. Prolonged participation further reduced the HCAI prevalence, in particular UTIs, despite the increasing age and associated frailty of the LTCF population, illustrating the potential value of surveillance.

Nursing home-associated bloodstream infection: A scoping review

OBJECTIVE

To update a 2005 review of nursing home-associated bloodstream infection (NHABSI) regarding sources, organisms, antibiotic resistance, and outcome.

METHODS

A scoping review of studies of NHABSI identified by searching Google Scholar and Medline with OVID for the period January 1, 2004, to June 30, 2021, was conducted.

RESULTS

Overall, 6 studies of NHABSI were identified. Only 1 study was conducted with residents in North American facilities whereas in the 2005 review all studies were conducted in North America. Escherichia coli was the most common blood isolate, the urinary tract was the most common source of NHABSI; and the case-fatality rates ranged from 21% to 28%. These findings were comparable to those in the 2005 review. However, the proportion of NHABSI episodes due to antibiotic-resistant organisms increased substantially compared to the 2005 review. The most common antibiotic-resistant organisms were extended-spectrum β-lactamase-producing E. coli and Klebsiella spp. The 2 studies that evaluated the relationship between appropriate empiric antibiotic therapy and outcome came to different conclusions.

CONCLUSIONS

The only major difference between the 2 reviews in the epidemiology of NHABSI was the marked increase in antibiotic resistance among blood isolates. Despite the increased antibiotic resistance, the case fatality rates in the current review were comparable to those reported in the 2005 review. However, the impact of appropriate empiric antibiotic therapy on outcome of NHABSI remains unclear.

Reimagining Infection Control in U.S. Nursing Homes in the Era of COVID-19

Residents of nursing homes (NHs) are susceptible to infection, and these facilities, particularly those that provide post-acute care services, are high-risk settings for the rapid spread of communicable respiratory and gastrointestinal illnesses, as well as antibiotic-resistant bacteria. The complexity of medical care delivered in most NHs has increased dramatically over the past 2 decades; however, the structure and resources supporting the practice of infection prevention and control in these facilities has failed to keep pace. Rising numbers of infections caused by Clostridioides difficile and multidrug-resistant organisms, as well as the catastrophic effects of COVID-19 have pushed NH infection control resources to a breaking point. Recent changes to federal regulations require NHs to devote greater resources to the facility infection control program. However, additional changes are needed if sustained improvements in the prevention and control of infections and antibiotic resistance in NHs are to be achieved.

Staphylococcus aureus adhesion to the host

Staphylococcus aureus is a pathobiont capable of colonizing and infecting most tissues within the human body, resulting in a multitude of different clinical outcomes. Adhesion of S. aureus to the host is crucial for both host colonization and the establishment of infections. Underlying the pathogen's success is a complex and diverse arsenal of adhesins. In this review, we discuss the different classes of adhesins, including a consideration of the various adhesion sites throughout the body and the clinical outcomes of each infection type. The development of therapeutics targeting the S. aureus host-pathogen interaction is a relatively understudied area. Due to the increasing global threat of antimicrobial resistance, it is crucial that innovative and alternative approaches are considered. Neutralizing virulence factors, through the development of antivirulence agents, could reduce bacterial pathogenicity and the ever-increasing burden of S. aureus infections. This review provides insight into potentially efficacious adhesion-associated targets for the development of novel decolonizing and antivirulence strategies.

Colonization and Infection of Indwelling Medical Devices by Staphylococcus aureus with an Emphasis on Orthopedic Implants

The use of indwelling medical devices has constantly increased in recent years and has revolutionized the quality of life of patients affected by different diseases. However, despite the improvement of hygiene conditions in hospitals, implant-associated infections remain a common and serious complication in prosthetic surgery, mainly in the orthopedic field, where infection often leads to implant failure. Staphylococcus aureus is the most common cause of biomaterial-centered infection. Upon binding to the medical devices, these bacteria proliferate and develop dense communities encased in a protective matrix called biofilm. Biofilm formation has been proposed as occurring in several stages-(1) attachment; (2) proliferation; (3) dispersal-and involves a variety of host and staphylococcal proteinaceous and non-proteinaceous factors. Moreover, biofilm formation is strictly regulated by several control systems. Biofilms enable staphylococci to avoid antimicrobial activity and host immune response and are a source of persistent bacteremia as well as of localized tissue destruction. While considerable information is available on staphylococcal biofilm formation on medical implants and important results have been achieved on the treatment of biofilms, preclinical and clinical applications need to be further investigated. Thus, the purpose of this review is to gather current studies about the mechanism of infection of indwelling medical devices by S. aureus with a special focus on the biochemical factors involved in biofilm formation and regulation. We also provide a summary of the current therapeutic strategies to combat biomaterial-associated infections and highlight the need to further explore biofilm physiology and conduct research for innovative anti-biofilm approaches.

Catheter-Associated Urinary Tract Infections: Current Challenges and Future Prospects

Catheter-associated urinary tract infection (CAUTI) is the most common healthcare-associated infection and cause of secondary bloodstream infections. Despite many advances in diagnosis, prevention and treatment, CAUTI remains a severe healthcare burden, and antibiotic resistance rates are alarmingly high. In this review, current CAUTI management paradigms and challenges are discussed, followed by future prospects as they relate to the diagnosis, prevention, and treatment. Clinical and translational evidence will be evaluated, as will key basic science studies that underlie preventive and therapeutic approaches. Novel diagnostic strategies and treatment decision aids under development will decrease the time to diagnosis and improve antibiotic accuracy and stewardship. These include several classes of biomarkers often coupled with artificial intelligence algorithms, cell-free DNA, and others. New preventive strategies including catheter coatings and materials, vaccination, and bacterial interference are being developed and investigated. The antibiotic pipeline remains insufficient, and new strategies for the identification of new classes of antibiotics, and rational design of small molecule inhibitor alternatives, are under development for CAUTI treatment.

Prospective assessment of catheter-associated bacteriuria clinical presentation, epidemiology, and colonization dynamics in nursing home residents

BACKGROUND

Catheterization facilitates continuous bacteriuria, for which the clinical significance remains unclear. This study aimed to determine the clinical presentation, epidemiology, and dynamics of bacteriuria in a cohort of long-term catheterized nursing home residents.

METHODS

Prospective urine culture, urinalysis, chart review, and assessment of signs and symptoms of infection were performed weekly for 19 study participants over 7 months. All bacteria ≥ 1 × 10³ cfu/mL were cultured, isolated, identified, and tested for susceptibility to select antimicrobials.

RESULTS

In total, 226 of the 234 urine samples were polymicrobial (97%), with an average of 4.7 isolates per weekly specimen. A total of 228 urine samples (97%) exhibited ≥ 1 × 10⁶ CFU/mL, 220 (94%) exhibited abnormal urinalysis, 126 (54%) were associated with at least 1 possible sign or symptom of infection, and 82 (35%) would potentially meet a standardized definition of catheter-associated urinary tract infection (CAUTI), but only 3 had a caregiver diagnosis of CAUTI. Bacterial isolates (286; 30%) were resistant to a tested antimicrobial agent, and bacteriuria composition was remarkably stable despite a combined total of 54 catheter changes and 23 weeks of antimicrobial use.

CONCLUSION

Bacteriuria composition was largely polymicrobial, including persistent colonization by organisms previously considered to be urine culture contaminants. Neither antimicrobial use nor catheter changes sterilized the urine, at most resulting in transient reductions in bacterial burden followed by new acquisition of resistant isolates. Thus, this patient population exhibits a high prevalence of bacteriuria coupled with potential indicators of infection, necessitating further exploration to identify sensitive markers of true infection.

FUNDING

This work was supported by the NIH (R00 DK105205, R01 DK123158, UL1 TR001412).

Focused Ultrasound Biofilm Ablation: Investigation of Histotripsy for the Treatment of Catheter-Associated Urinary Tract Infections (CAUTIs)

Urinary catheters often become contaminated with biofilms, resulting in catheter-associated urinary tract infections (CAUTIs) that adversely affect patient outcomes. Histotripsy is a noninvasive focused ultrasound therapy previously developed for the noninvasive ablation of cancerous tumors and soft tissues. Histotripsy has also previously shown the ability to treat biofilms on glass slides and surgical meshes. Here, we investigate the potential of histotripsy for the treatment of CAUTIs for the first time in vitro. Clinically relevant catheter materials (Tygon, Silicone, and latex catheter mimics) and commonly used clinical catheters were tested to determine the feasibility of producing luminal histotripsy bubble clouds. A Pseudomonas aeruginosa (strain PA14) biofilm model was developed and tested to produce luminal biofilms in an in vitro Tygon catheter mimic. This model was treated with histotripsy to determine the ability to remove a luminal biofilm. Finally, the bactericidal effects of histotripsy were tested by treating PA14 suspended inside the Tygon catheter mimic. Results showed that histotripsy produced precise luminal cavitation within all tested catheter mimics and clinical catheters. Histotripsy treatment of a PA14 biofilm with histotripsy reduced luminal biofilm OD590 signal down to background levels. Further, the treatment of suspended PA14 in Luria-Bertani (LB) showed a 3.45 ± 0.11 log₁₀ reduction in CFU/mL after six histotripsy scans across the catheter mimics. Overall, the results of this study demonstrate the potential of histotripsy to provide a new modality for removing bacterial biofilms from catheter-based medical devices and suggest that additional work is warranted to investigate histotripsy for the treatment of CAUTIs and other biomaterial-associated infections.

Methicillin and Vancomycin Resistant Staphylococcus aureus and Associated Factors from Surgical Ward Inpatients at Debre Markos Referral Hospital, Northwest Ethiopia

Introduction

Staphylococcus aureus is a well-known superbug and leading causes of wound infections. The clinical epidemiology of methicillin resistant S. aureus (MRSA) and vancomycin resistant S. aureus (VRSA) is not well documented in Ethiopia. The aim of this study was to determine the proportion of MRSA, VRSA and associated factors from surgical inpatients in Debre Markos Referral Hospital (DMRH), Northwest Ethiopia.

Methods

A facility-based cross-sectional study was conducted from February to April 2020 at DMRH. A structured questionnaire was used to gather demographic and clinical data. Wound swab was collected from inpatients and then inoculated on blood agar and mannitol salt agar. The presence of MRSA and VRSA was determined using the cefoxitin (30 μg) antibiotic disk diffusion and vancomycin E-test methods, respectively. The data were analyzed using SPSS 20. Data were analyzed using bivariate and multivariate logistic regression analysis. A P-value <0.05 was considered statistically significant.

Results

A total of 242 wound cases were enrolled and the majority of them were males 172 (71.1%). Among the total enrolled cases, S. aureus was identified from 71 (29.3%) of the admitted patients. The proportion of MRSA was 32 (13.22%) and that of VRSA was 4.1%. The proportion of vancomycin intermediate S. aureus (VISA) was gauged at 4.5%. Hospital stay over 72 hrs, wound depth, current antibiotic use, and previous history of wound infection showed statistically significant association with MRSA. On the contrary, VRSA did not showed any significant association against the analyzed variables.

Conclusion

High proportions of S. aureus isolates became MRSA; resistant to all β-lactam antimicrobial agents excluding newer cephalosporin. In addition, the proportion of VRSA/VISA was also high. Multiple variables demonstrated significant associations with MRSA. Hence, intervention measures for MRSA risk groups must be in place. Furthermore, hospital infection control and an antibiotic stewardship program should be strengthened.

Enterococcus faecalis Polymicrobial Interactions Facilitate Biofilm Formation, Antibiotic Recalcitrance, and Persistent Colonization of the Catheterized Urinary Tract

Indwelling urinary catheters are common in health care settings and can lead to catheter-associated urinary tract infection (CAUTI). Long-term catheterization causes polymicrobial colonization of the catheter and urine, for which the clinical significance is poorly understood. Through prospective assessment of catheter urine colonization, we identified Enterococcus faecalis and Proteus mirabilis as the most prevalent and persistent co-colonizers. Clinical isolates of both species successfully co-colonized in a murine model of CAUTI, and they were observed to co-localize on catheter biofilms during infection. We further demonstrate that P. mirabilis preferentially adheres to E. faecalis during biofilm formation, and that contact-dependent interactions between E. faecalis and P. mirabilis facilitate establishment of a robust biofilm architecture that enhances antimicrobial resistance for both species. E. faecalis may therefore act as a pioneer species on urinary catheters, establishing an ideal surface for persistent colonization by more traditional pathogens such as P. mirabilis.

Natural Course of Acute Cholecystitis in Patients Treated With Percutaneous Transhepatic Gallbladder Drainage Without Elective Cholecystectomy

BACKGROUND

Percutaneous transhepatic gallbladder drainage (PTGBD) is an alternative treatment for acute cholecystitis (AC). We aimed to understand the natural course of AC in patients treated with PTGBD but without later definitive treatments, such as laparoscopic cholecystectomy.

METHODS

This was a retrospective study of the period from June 2010 to December 2016, during which time 2371 patients were diagnosed with AC and 625 received PTGBD treatment. Among the 625 patients, 237 received no definitive treatment. A biliary event after the initial AC episode was the outcome of interest. In addition, the competing risk of death unrelated to biliary causes was present in the cohort. Therefore, a competing risk model was applied for analysis.

RESULTS

The cumulative incidence of biliary events was 29.8% with a median of 4.27 months, while the competing event, i.e., death unrelated to a biliary event, was noted in 14.9% of patients with a median 23.54 months. The risk factors of biliary events were prolonged PTGBD indwelling and an abnormal PTGBD cholangiogram. The risk factors of death unrelated to a biliary event included a high Charlson comorbidity index and the initial AC severity.

CONCLUSIONS

Definitive cholecystectomy is still recommended for patients undergoing PTGBD treatment due to the high incidence of later biliary events. A thorough preoperative evaluation is necessary for those patients before elective cholecystectomy because of the inferior life expectancy and physical status.

Infection prevention in long-term care: re-evaluating the system using a human factors engineering approach

The emergence and spread of extensively multidrug-resistant organisms is a public health crisis, and long-term care settings have been identified as a reservoir for the cultivation of these organisms. Long-term care settings are now taking on increasingly ill residents with complicated medical problems, indwelling devices, and significant healthcare exposure, all of which are considered risk factors selecting for resistant organisms. Despite this, guidelines addressing infection prevention procedures in long-term care remain vague, and implementation of these guidelines is challenging, largely due to staff turnover, limited resources, knowledge gaps, and lack of organizational support. Human factors engineering approaches have emerged as an important innovation to address patient safety issues and develop interventions in the healthcare work system (ie, tools and technologies, tasks, organization, physical environment) that support human performance, which, in turn, lead to improvements in processes (eg, compliance with infection prevention guidelines) and outcomes (eg, reduced infection rates). We propose the concept of using the methods and approaches from the scientific field of human factors engineering to address the unique challenges of implementing infection prevention in the long-term care setting.

Effect of far ultraviolet light emitted from an optical diffuser on methicillin-resistant Staphylococcus aureus in vitro

Drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are a target for new antimicrobial technologies. Far-UVC technology is an emerging disinfection method that directly kills microorganisms using light. In contrast with conventional UV sterilization, far-UVC light has antimicrobial capabilities without apparent harm to mammalian cells. This study examines the application of 224 nm far-UVC light delivered from a laser using an optical diffuser towards the goal of protecting against bacterial invasion around skin penetrating devices. Delivery of far-UVC using a laser and optical fibers enables exposure to unique geometries that would otherwise be shielded when using a lamp. Testing of the bactericidal potential of diffusing the far-UVC laser output over a large area was tested and yielded qualitative area killing results. The killing of MRSA using this method was also examined using an in vitro survival assay. Results followed a classic log-linear disinfection model with a rate constant of k = 0.51 cm2/mJ, which corresponds to an inactivation cross section of D90 = 4.5 mJ/cm2. This study establishes far-UVC delivered from a laser through an optical diffuser as a viable solution for disinfection of susceptible regions such as around catheters, drivelines, or other skin penetrating medical devices.

Colonization of medical devices by staphylococci

The use of medical devices in modern medicine is constantly increasing. Despite the multiple precautionary strategies that are being employed in hospitals, which include increased hygiene and sterilization measures, bacterial infections on these devices still happen frequently. Staphylococci are among the major causes of medical device infection. This is mostly due to the strong capacity of those bacteria to form device-associated biofilms, which provide resistance to chemical and physical treatments as well as attacks by the host's immune system. Biofilm development is a multistep process with specific factors participating in each step. It is tightly regulated to provide a balance between biofilm expansion and detachment. Detachment from a biofilm on a medical device can lead to severe systemic infection, such as bacteremia and sepsis. While our understanding of staphylococcal biofilm formation has increased significantly and staphylococcal biofilm formation on medical devices is among the best understood biofilm-associated infections, the extensive effort put in preclinical studies with the goal to find novel therapies against staphylococcal device-associated infections has not yet resulted in efficient, applicable therapeutic options for that difficult-to-treat type of disease.

Economic Evaluation of a Catheter-Associated Urinary Tract Infection Prevention Program in Nursing Homes

OBJECTIVE

To assess the economic effect and cost effectiveness of a targeted catheter-associated urinary tract infection (CAUTI) prevention intervention in the nursing home (NH) setting.

DESIGN

Randomized clinical trial.

SETTING

Community-based NHs (N=12).

PARTICIPANTS

NH residents with indwelling urinary catheters (N=418).

INTERVENTION

Standard care versus infection prevention program involving barrier precautions, active surveillance, and NH staff education.

MEASUREMENTS

Costs of the intervention, costs of disease, and health outcomes were used to calculate an incremental cost-effectiveness ratio for the intervention. Data came from intervention results and the literature and outcomes were analyzed over one year.

RESULTS

A 120-bed NH would have program costs of $20,279/year. The cost of disease treatment would be reduced by $54,316 per year, resulting in a $34,037 net cost savings. Most of this savings would come from fewer CAUTI hospitalizations ($39,180), with $15,136 in savings from CAUTI care within the NH. The intervention also yielded a gain of 0.197 quality-adjusted life-years (QALYs). Taking into account uncertainty in all parameters suggests there is an 85% chance that the intervention is cost-saving.

CONCLUSIONS

The CAUTI prevention program is expected to benefit payers by reducing costs and improving health outcomes. Because the savings accrue to payers and not to NHs, payers such as Medicare and private insurers may want to provide incentives for NHs to implement such programs.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01062841.

Challenges and Strategies for Prevention of Multidrug-Resistant Organism Transmission in Nursing Homes

PURPOSE OF REVIEW

Nursing home residents are at high risk for colonization and infection with bacterial pathogens that are multidrug-resistant organisms (MDROs). We discuss challenges and potential solutions to support implementing effective infection prevention and control practices in nursing homes.

RECENT FINDINGS

Challenges include a paucity of evidence that addresses MDRO transmission during the care of nursing home residents, limited staff resources in nursing homes, insufficient infection prevention education in nursing homes, and perceptions by nursing home staff that isolation and contact precautions negatively influence the well being of their residents. A small number of studies provide evidence that specifically address these challenges. Their outcomes support a paradigm shift that moves infection prevention and control practices away from a pathogen-specific approach and toward one that focuses on resident risk factors.

Long-Term Outcomes of Patients with Acute Cholecystitis after Successful Percutaneous Cholecystostomy Treatment and the Risk Factors for Recurrence: A Decade Experience at a Single Center

BACKGROUND

Percutaneous cholecystostomy tube (PCT) has been effectively used for the treatment of acute cholecystitis (AC) for patients unsuitable for early cholecystectomy. This retrospective study investigated the recurrence rate after successful PCT treatment and factors associated with recurrence.

METHODS

We reviewed patients treated with PCT for AC from October 2004 through December 2013. Patients with successful PCT treatment were those who were free from persistent PCT drainage. We used multivariable logistic regression analysis sequentially to identify factors associated with each outcome.

RESULTS

The study included 184 patients (mean age: 70.1 years). The average duration for parenteral antibiotics was 14.4 days and 20.0 days for PCT drainage. The one-year recurrence rate was 9.2% (17/184) with most recurrences occurring within two months (6.5%, 12/184) of the procedure. Complicated cholecystitis (odds ratio [OR]: 4.67; 95% confidence interval [CI]: 1.44-15.70; P = 0.01) and PCT drainage duration >32 days (OR: 4.92; 95% CI: 1.03-23.53; P = 0.05) positively correlated with one-year recurrence; parenteral antibiotics duration >10 days (OR: 0.21; 95% CI: 0.05-0.68; P = 0.01) was inversely associated with one-year recurrence.

CONCLUSIONS

The recurrence rate was low for patients after successful PCT treatment. Predictors for recurrence included the severity of initial AC and subsequently provided treatments.

Optimizing Antibiotic Stewardship in Nursing Homes: A Narrative Review and Recommendations for Improvement

The emerging crisis in antibiotic resistance and concern that we now sit on the precipice of a post-antibiotic era have given rise to advocacy at the highest levels for widespread adoption of programmes that promote judicious use of antibiotics. These antibiotic stewardship programmes, which seek to optimize antibiotic choice when clinically indicated and discourage antibiotic use when clinically unnecessary, are being implemented in an increasing number of acute care facilities, but their adoption has been slower in nursing homes. The antibiotic prescribing process in nursing homes is fundamentally different from that observed in hospital and clinic settings, with formidable challenges to implementation of effective antibiotic stewardship. Nevertheless, an emerging body of research points towards ways to improve antibiotic prescribing practices in nursing homes. This review summarizes the findings of this research and presents ways in which antibiotic stewardship can be implemented and optimized in the nursing home setting.

Development of broad-spectrum antibiofilm drugs: strategies and challenges

ABSTRACT 

The severity of many chronic bacterial infections is mainly due to the biofilm mode of life adapted by pathogenic bacteria. The bacteria in biofilm-stage exhibit high resistance to host immune responses and antimicrobials, which complicates the treatment process and results in life threatening conditions. Most of the chronic infections are polymicrobial in nature. In order to combat the polymicrobial biofilm infections and to increase the efficiency of antimicrobials, there is an urgent need for broad-spectrum antibiofilm drugs. This review discusses the clinical needs and current status of broad-spectrum antibiofilm drugs with special emphasis on prospective strategies and hurdles in the process of new drug discovery.

Device-related infections in long-term healthcare facilities: the challenge of prevention

The world is aging and the number of elderly multimorbid patients is steadily increasing. The limited numbers of acute care beds in hospitals, in addition to the need to reduce costs, has led to the introduction of efficient discharge policies, which in turn have increased demand for beds in nursing homes and long-term care facilities (LTCFs). As a consequence, the number of postacute LTCF residents is rising, as is the number of residents requiring complex medical care delivered by use of indwelling medical devices. These devices place patients at a heightened risk for infection. Furthermore, infection control resources in LTCFs are often limited. This article reviews the preventive measures that should be taken in LTCFs to reduce the risk of device-related infections.

Evolution of antimicrobial peptides to self-assembled peptides for biomaterial applications

Biomaterial-related infections are a persistent burden on patient health, recovery, mortality and healthcare budgets. Self-assembled antimicrobial peptides have evolved from the area of antimicrobial peptides. Peptides serve as important weapons in nature, and increasingly medicine, for combating microbial infection and biofilms. Self-assembled peptides harness a "bottom-up" approach, whereby the primary peptide sequence may be modified with natural and unnatural amino acids to produce an inherently antimicrobial hydrogel. Gelation may be tailored to occur in the presence of physiological and infective indicators (e.g. pH, enzymes) and therefore allow local, targeted antimicrobial therapy at the site of infection. Peptides demonstrate inherent biocompatibility, antimicrobial activity, biodegradability and numerous functional groups. They are therefore prime candidates for the production of polymeric molecules that have the potential to be conjugated to biomaterials with precision. Non-native chemistries and functional groups are easily incorporated into the peptide backbone allowing peptide hydrogels to be tailored to specific functional requirements. This article reviews an area of increasing interest, namely self-assembled peptides and their potential therapeutic applications as innovative hydrogels and biomaterials in the prevention of biofilm-related infection.

Catheter associated urinary tract infections

Urinary tract infection attributed to the use of an indwelling urinary catheter is one of the most common infections acquired by patients in health care facilities. As biofilm ultimately develops on all of these devices, the major determinant for development of bacteriuria is duration of catheterization. While the proportion of bacteriuric subjects who develop symptomatic infection is low, the high frequency of use of indwelling urinary catheters means there is a substantial burden attributable to these infections. Catheter-acquired urinary infection is the source for about 20% of episodes of health-care acquired bacteremia in acute care facilities, and over 50% in long term care facilities. The most important interventions to prevent bacteriuria and infection are to limit indwelling catheter use and, when catheter use is necessary, to discontinue the catheter as soon as clinically feasible. Infection control programs in health care facilities must implement and monitor strategies to limit catheter-acquired urinary infection, including surveillance of catheter use, appropriateness of catheter indications, and complications. Ultimately, prevention of these infections will require technical advances in catheter materials which prevent biofilm formation.

Particle exposures and infections

Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Cigarette smoking, burning of biomass, dust storms, mining, agricultural work, environmental tobacco smoke (ETS), wood stoves, traffic-related emissions, gas stoves, and ambient air pollution are all particle-related exposures associated with an increased risk for respiratory infections. In addition, cigarette smoking, burning of biomass, dust storms, mining, and ETS can result in an elevated risk for tuberculosis, atypical mycobacterial infections, and meningitis. One of the mechanisms for particle-related infections includes an accumulation of iron by surface functional groups of particulate matter (PM). Since elevations in metal availability are common to every particle exposure, all PM potentially contributes to these infections. Therefore, exposures to wood stove emissions, diesel exhaust, and air pollution particles are predicted to increase the incidence and prevalence of tuberculosis, atypical mycobacterial infections, and meningitis, albeit these elevations are likely to be small and detectable only in large population studies. Since iron accumulation correlates with the presence of surface functional groups and dependent metal coordination by the PM, the risk for infection continues as long as the particle is retained. Subsequently, it is expected that the cessation of exposure will diminish, but not totally reverse, the elevated risk for infection.

Pig dorsum model for examining impaired wound healing at the skin-implant interface of percutaneous devices

Percutaneous medical devices are indispensable in contemporary clinical practice, but the associated incidence of low to moderate mortality infections represents a significant economic and personal cost to patients and healthcare providers. Percutaneous osseointegrated prosthetics also suffer from a similar risk of infection, limiting their clinical acceptance and usage in patients with limb loss. We hypothesized that transepidermal water loss (TEWL) management at the skin-implant interface may improve and maintain a stable skin-to-implant interface. In this study, skin reactions in a 3-month, pig dorsum model were assessed using standard histology, immunohistochemistry, and quantitative image analysis. Immunohistochemical analysis of peri-implant tissue explants showed evidence of: continuous healing (cytokeratin 6+), hypergranulation tissue (procollagen+), hyper-vascularity (collagen 4+), and the presence of fibrocytes (CD45+ and procollagen type 1+). Importantly, the gross skin response was correlated to a previous load-bearing percutaneous osseointegrated prosthetic sheep study conducted in our lab. The skin responses of the two models indicated a potentially shared mechanism of wound healing behavior at the skin-implant interface. Although TEWL management did not reduce skin migration at the skin-implant interface, the correlation of qualitative and quantitative measures validated the pig dorsum model as a high-throughput platform for translational science based percutaneous interface investigations in the future.

Specialty care delivery: bringing infectious disease expertise to the residents of a Veterans Affairs long-term care facility

OBJECTIVE

To initiate a long-term care facility (LTCF) infectious disease (LID) service that provides on-site consultations to LTCF residents to improve the care of residents with possible infections.

DESIGN

Clinical demonstration project.

SETTING

A 160-bed LTCF affiliated with a tertiary care Veterans Affairs (VA) hospital.

PARTICIPANTS

Residents referred to the LID team.

MEASUREMENTS

The reason for and source of LTCF residents' referral to the LID team and their demographic characteristics, infectious disease diagnoses, interventions, and hospitalizations were determined.

RESULTS

Between July 2009 and December 2010, the LID consultation service provided 291 consultations for 250 LTCF residents. Referrals came from LTCF staff (75%) or the VA hospital's ID consult service (25%). The most common diagnoses were Clostridium difficile infection (14%), asymptomatic bacteriuria (10%), and urinary tract infection (10%). More than half of referred residents were receiving antibiotic therapy when they first saw the LID team; 46% of residents required an intervention. The most common interventions, stopping (32%) or starting (26%) antibiotics, were made in accordance with principles of antibiotic stewardship.

CONCLUSION

The LID team represents a novel and effective means to bring subspecialty care to LTCF residents.

Outcome after percutaneous cholecystostomy for acute cholecystitis: a single-center experience

BACKGROUND

Percutaneous cholecystostomy is an alternative treatment for acute cholecystitis patients with high surgical risk.

METHODS

One hundred and sixty-six patients consecutively treated by percutaneous cholecystostomy for acute cholecystitis in a single medical center were retrospectively reviewed.

RESULTS

The cohort included 121 males and 45 females with mean age of 75.9 years. The overall inhospital mortality rate was 15.1 % (n = 25). Elevated serum creatinine level at diagnosis [odds ratio (OR) 1.497; p = 0.020], septic shock (OR 11.755; p = 0.001), and development of cholecystitis during admission (OR 7.256; p = 0.007) were predictive of inhospital mortality. Of 126 patients who recovered from calculous cholecystitis, 11 experienced recurrent cholecystitis within 2 months. Serum C-reactive protein (CRP) level >15 mg dl(-1) at diagnosis [hazard ratio (HR) 10.141; p = 0.027] and drainage duration of cholecystostomy longer than 2 weeks (HR 3.638; p = 0.039) were independent risk factors of early recurrence. The 53 patients who underwent cholecystectomy had an 18.9 % perioperative complication rate and no operation-related mortality.

CONCLUSIONS

In-patients or those with septic shock or renal insufficiency have worse outcome. Prolonged drainage duration and high CRP level predict early recurrence. Removal of the drainage tube is recommended after resolution of the acute illness.