Epidemiology of antibiotic-associated colitis; isolation of Clostridium difficile from the hospital environment

Cleaning and decontamination of the healthcare environment

Evidence is accumulating for the role of cleaning in controlling hospital infections. Hospital pathogens such as meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), norovirus, multi-resistant Gram-negative bacilli and Clostridium difficile persist in the healthcare environment for considerable lengths of time. Cleaning with both detergent and disinfectant-based regimens help control these pathogens in both routine and outbreak situations. The most important transmission risk comes from organisms on frequently handled items because hand contact with a contaminated site could deliver a pathogen to a patient. Cleaning practices should be tailored to clinical risk, near-patient areas and hand-touch-sites and scientifically evaluated for all surfaces and equipment in today’s hospitals.

Contamination of healthcare workers' hands with Clostridium difficile spores after caring for patients with C. difficile infection

OBJECTIVE

We determined the percentage of healthcare workers' (HCWs') hands contaminated with Clostridium difficile spores after caring for patients with C. difficile infection (CDI) and risk factors associated with contamination.

DESIGN

Prospective study.

SETTING

A French university hospital.

METHODS

We compared the hand contamination rate among HCWs caring for patients with CDI (exposed group; n = 66) with that among an unexposed group (n = 44). Spores of C. difficile were recovered from the hands of HCWs after rubbing their fingers and palms in alcohol shortly after patient care. Associations between hand contamination and HCW category, type (patient or environment), and risk level (high or low risk) of HCW contacts and their respective duration as well as use of gloves were analyzed by bivariate and multivariate analysis.

RESULTS

C. difficile spores were detected on 24% of HCWs' hands in the exposed group and on 0% in the unexposed group (P < .001). In the exposed group, logistic regression, which adjusted for high-risk contact (ie, exposure to fecal soiling), contact with the environment, and contact with or without use of gloves, revealed that high-risk contact (adjusted odds ratio [aOR] per 1 contact increment, 2.78; 95% confidence interval [CI], 1.42-5.45; P = .003) and at least 1 contact without use of gloves (aOR, 6.26; 95% CI, 1.27-30.78; P = .02) were independently associated with HCW hand contamination by C. difficile spores.

CONCLUSIONS

Nearly one-quarter of HCWs have hands contaminated with C. difficile spores after routine care of patients with CDI. Hand contamination is positively associated with exposure to fecal soiling and lack of glove use.

Transfer efficiency of bacteria and viruses from porous and nonporous fomites to fingers under different relative humidity conditions

Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-μl drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm(2) of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (<6.8%) under low relative humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms.

Role of the environment in the transmission of Clostridium difficile in health care facilities

Recent data demonstrate that the contaminated hospital surface environment plays a key role in the transmission of Clostridium difficile. Enhanced environmental cleaning of rooms housing Clostridium difficile-infected patients is warranted, and, if additional studies demonstrate a benefit of "no-touch" methods (eg, ultraviolet irradiation, hydrogen peroxide systems), their routine use should be considered.

Shining light on materials--a self-sterilising revolution

This review focuses on the development of light activated antimicrobial surfaces. These surfaces kill microbes by the action of light and have potential applications in domestic and healthcare settings. The inspiration for the new self-cleaning surfaces originates from photodynamic therapy where light is used to locate and destroy tumours. The first generation photosensitiser molecules, based on a porphyrin ring structure, could be considered as bioinspired and chemically related to chlorophyll. The review looks at developments of both soft polymeric surfaces with either surface bound or impregnated photosensitiser molecules; and hard inorganic surfaces such as modified titanium dioxide. The bacterial kill mechanisms are looked into with both surface types showing primary microbial kill through a radical induced pathway. The hard inorganic surfaces also show low bacterial adherence by means of a light activated photo-wetting of the surfaces meaning that they are "Easy Clean" and wash off microbes uniformly.

Clostridium difficile: development of a novel candidate vaccine

Clostridium difficile has become the most frequent hospital-acquired infection in North America and the EU. C. difficile infection (CDI) is present worldwide and disease awareness is increasing. In the US, EU, and Canada, in addition to hospital diagnosed disease, CDI has also been reported with increasing frequency in the community. Hypervirulent strains have increased the morbidity and mortality associated with CDI. Current treatment options are suboptimal. Of all patients treated for CDI, 20% relapse and 65% of those experiencing a second relapse become chronic cases. An association between increased serum levels of IgG antibody against toxin A and asymptomatic carriage of C. difficile provides a rationale for vaccine development. Sanofi Pasteur's C. difficile candidate vaccine is being developed for the prevention of primary disease. The target population is adults at risk of CDI, those with planned hospitalization, long-term care/nursing home residents, and adults with co-morbidities requiring frequent/prolonged antibiotic use.

Clostridium difficile Infection in Children: Current State and Unanswered Questions

The incidence of Clostridium difficile infection (CDI) in children has increased over the past decade. In recent years, new and intriguing data on pediatric CDI have emerged. Community-onset infections are increasingly recognized, even in children who have not previously received antibiotics. A hypervirulent strain is responsible for up to 20% of pediatric CDI cases. Unique risk factors for CDI in children have been identified. Advances in diagnostic testing strategies, including the use of nucleic acid amplification tests, have raised new questions about the optimal approach to diagnosing CDI in children. Novel therapeutic options are available for adult patients with CDI, raising questions about the use of these agents in children. Updated recommendations about infection prevention and control measures are now available. We summarize these recent developments in pediatric CDI in this review and also highlight remaining knowledge gaps that should be addressed in future research efforts.

Clostridium difficile outbreaks: prevention and treatment strategies

The incidence and severity of Clostridium difficile infection (CDI) have increased dramatically over the past decade. Its treatment, however, has largely remained the same with the exception of oral vancomycin use as a first-line agent in severe disease. From 1999 to 2004, 20,642 deaths were attributed to CDI in the United States, almost 7 times the rate of all other intestinal infections combined. Worldwide, several major CDI outbreaks have occurred, and many of these were associated with the NAP1 strain. This ‘epidemic’ strain has contributed to the rising incidence and mortality of CDI. The purpose of this article is to review the current management, treatment, infection control, and prevention strategies that are needed to combat this increasingly morbid disease.

Nosocomial diarrhea: a review of pathophysiology, etiology, and treatment strategies

Diarrhea is a frequent complication among hospitalized patients. Nosocomial diarrhea is generally diagnosed as increased frequency and decreased consistency of stools developing after 72 hours of hospitalization. The causes of nosocomial diarrhea may be infectious or noninfectious. Noninfectious etiologies occur most commonly, and are often adverse effects of medications or enteral nutrition therapies. Infectious etiologies are most concerning and include Clostridium difficile and norovirus. Patients with nosocomial diarrhea should be placed in isolation with contact precautions in place until the presence of C difficile infection is determined. Irrespective of etiology, diarrhea can cause serious complications in hospitalized patients, including malnutrition, hemodynamic instability, metabolic acidosis, and potentially fatal pseudomembranous colitis. This article reviews nosocomial diarrhea, including its pathophysiology, infectious and noninfectious causes, and treatment strategies based on identified cause.

Michigan Clostridium difficile hospital discharges: frequency, mortality, and charges, 2002-2008

OBJECTIVE

Clostridium difficile (C. difficile) causes an intestinal bacterial infection of increasing importance in Michigan residents and health-care facilities. The specific burden and health-care costs of C. difficile infection (CDI) were previously unknown. We evaluated the frequency, mortality, and health-care charges of CDI from Michigan hospital discharge data.

METHODS

The Michigan Department of Community Health purchased discharge data from all Michigan acute care hospitals from the Michigan Health and Hospital Association. We extracted all hospital discharges from 2002 through 2008 containing the International Classification of Diseases, Ninth Revision code for intestinal infection due to C. difficile. Discharges were stratified by principle diagnosis and comorbidity level. Total hospitalization charges were standardized to the 2008 U.S. dollar.

RESULTS

From 2002 through 2008, 68,686 hospital discharges with CDI occurred. The annual rate increased from 463.1 to 1096.5 CDI discharges per 100,000 discharges. CDI discharge rates were substantially higher among the elderly, females, and black people. Of all CDI discharges, 5,924 (8.6%) patients died. The mean total health-care charge for the time period was $67,149, and the annual mean increased 35% from 2002 to 2008. Hospital charges varied significantly by race/ethnicity and age. People with Medicaid insurance accrued the highest charges.

CONCLUSION

Across Michigan, the CDI burden is growing substantially and affecting vulnerable populations. Surveillance utilizing hospital discharge data can illuminate trends and inform intervention targets. To reduce disease and health-care charges, increased prevention and infection-control efforts should be directed toward high-risk populations, such as the elderly.

N-CDAD in Canada: results of the Canadian Nosocomial Infection Surveillance Program 1997 N-CDAD Prevalence Surveillance Project

BACKGROUND

A 1996 preproject survey among Canadian Hospital Epidemiology Committee (CHEC) sites revealed variations in the prevention, detection, management and surveillance of Clostridium difficile-associated diarrhea (CDAD). Facilities wanted to establish national rates of nosocomially acquired CDAD (N-CDAD) to understand the impact of control or prevention measures, and the burden of N-CDAD on health care resources. The CHEC, in collaboration with the Laboratory Centre for Disease Control (Health Canada) and under the Canadian Nosocomial Infection Surveillance Program, undertook a prevalence surveillance project among selected hospitals throughout Canada.

OBJECTIVE

To establish national prevalence rates of N-CDAD.

METHODS

For six weeks in 1997, selected CHEC sites tested all diarrheal stools from inpatients for either C difficile toxin or C difficile bacteria with evidence of toxin production. Questionnaires were completed for patients with positive stool assays who met the case definitions.

RESULTS

Nineteen health care facilities in eight provinces participated in the project. The overall prevalence of N-CDAD was 13.0% (95% CI 9.5% to 16.5%). The mean number of N-CDAD cases were 66.3 cases/100,000 patient days (95% CI 37.5 to 95.1) and 5.9 cases/1000 patient admissions (95% CI 3.4 to 8.4). N-CDAD was found most frequently in older patients and those who had been hospitalized for longer than two weeks in medical or surgical wards.

CONCLUSIONS

This national prevalence surveillance project, which established N-CDAD rates, is useful as 'benchmark' data for Canadian health care facilities, and in understanding the patterns and impact of N-CDAD.

Hypervirulent Clostridium difficile PCR-ribotypes exhibit resistance to widely used disinfectants

The increased prevalence of Clostridium difficile infection (CDI) has coincided with enhanced transmissibility and severity of disease, which is often linked to two distinct clonal lineages designated PCR-ribotype 027 and 017 responsible for CDI outbreaks in the USA, Europe and Asia. We assessed sporulation and susceptibility of three PCR-ribotypes; 012, 017 and 027 to four classes of disinfectants; chlorine releasing agents (CRAs), peroxygens, quaternary ammonium compounds (QAC) and biguanides. The 017 PCR-ribotype, showed the highest sporulation frequency under these test conditions. The oxidizing biocides and CRAs were the most efficacious in decontamination of C. difficile vegetative cells and spores, the efficacy of the CRAs were concentration dependent irrespective of PCR-ribotype. However, there were differences observed in the susceptibility of the PCR-ribotypes, independent of the concentrations tested for Virkon®, Newgenn®, Proceine 40® and Hibiscrub®. Whereas, for Steri7® and Biocleanse® the difference observed between the disinfectants were dependent on both PCR-ribotype and concentration. The oxidizing agent Perasafe® was consistently efficacious across all three PCR ribotypes at varying concentrations; with a consistent five Log10 reduction in spore titre. The PCR-ribotype and concentration dependent differences in the efficacy of the disinfectants in this study indicate that disinfectant choice is a factor for llimiting the survival and transmission of C. difficile spores in healthcare settings.

Best strategies in recurrent or persistent Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is the primary cause of antibiotic-associated colitis and 15-25% of nosocomial antibiotic-associated diarrhea. Its clinical manifestations can range from mild diarrhea to toxic megacolon, bowel perforation, septic shock, and death. Over the past decade, more virulent strains have become increasingly common causes, and the incidence of CDI has risen, especially in elderly patients. These developments have led to an increase in recurrent CDI, which is more difficult to treat. This review focuses on recurrent CDI and its treatment.

METHODS

MEDLINE review using search terms Clostridium difficile, Clostridium difficile infection, recurrent Clostridium difficile infection.

RESULTS

A first recurrence may be treated with the same regimen as the first episode. Metronidazole 500 mg q 8 h for 10-14 days is the drug of choice for moderate infection, and vancomycin 125 mg q 6 h for 10-14 days is the drug of choice for severe CDI. Metronidazole should not be used for treatment of subsequent recurrences because of potential neurotoxicity and hepatic toxicity. Second recurrences should be treated with an oral vancomycin course and taper: 125 mg q 6  h × 10-14 days, 125 mg q 12 h × 7 days, 125 mg q 24 h × 7 days, 125 mg q 48-72  h × 2-8 weeks. Alternative agents are fecal bacteriotherapy, a "rifaximin chaser," nitazoxanide, probiotics, and intravenous immunoglobulin. Fidaxomicin has been approved recently. Monoclonal antibodies against C. difficile toxin remain investigational.

CONCLUSION

Treatment of recurrent CDI remains challenging. Because of the lack of high-quality studies, recommendations for treatment are based on expert opinion. Metronidazole and vancomycin are the mainstays of treatment for both the initial infection and the first recurrence. For second recurrences, a vancomycin course plus taper is recommended. For subsequent recurrences, treatment options are many, with no one approach being entirely satisfactory. New drugs (fidaximicin) and treatments (monoclonal antibodies against the causative toxin) appear promising.

Efficacy of decontaminants and disinfectants against Clostridium difficile

Clostridium difficile is a common nosocomial pathogen transmitted mainly via its spores. These spores can remain viable on contaminated surfaces for several months and are resistant to most commonly used cleaning agents. Thus, effective decontamination of the environment is essential in preventing the transmission of C. difficile in health-care establishments. However, this emphasis on decontamination must also be extended to laboratories due to risk of exposure of staff to potentially virulent strains. Though few cases of laboratory-acquired infection have been reported, the threat of infection by C. difficile in the laboratory is real. Our aim was to test the efficacy of four disinfectants, Actichlor, MicroSol 3+, TriGene Advance and Virkon, and one laboratory decontaminant, Decon 90, against vegetative cells and spores of C. difficile. Five strains were selected for the study: the three most commonly encountered epidemic strains in Scotland, PCR ribotypes 106, 001 and 027, and control strains 630 and VPI 10463. MICs were determined by agar dilution and broth microdilution. All the agents tested inhibited the growth of vegetative cells of the selected strains at concentrations below the recommended working concentrations. Additionally, their effect on spores was determined by exposing the spores of these strains to different concentrations of the agents for different periods of time. For some of the agents, an exposure of 10 min was required for sporicidal activity. Further, only Actichlor was able to bring about a 3 log(10) reduction in spore numbers under clean and dirty conditions. It was also the only agent that decontaminated different hard, non-porous surfaces artificially contaminated with C. difficile spores. However, this too required an exposure time of more than 2 min and up to 10 min. In conclusion, only the chlorine-releasing agent Actichlor was found to be suitable for the elimination of C. difficile spores from the environment, making it the agent of choice for the decontamination of laboratory surfaces.

Preventing Clostridium difficile infections: an executive summary of the Association for Professionals in Infection Control and Epidemiology's elimination guide

This article is an executive summary of the Association for Professionals in Infection Control and Epidemiology's Clostridium difficile infection elimination guide. Infection preventionists are encouraged to obtain the original, full-length elimination guide for more thorough coverage of C difficile infection prevention.

Evaluation of sporicidal activities of selected environmental surface disinfectants: carrier tests with the spores of Clostridium difficile and its surrogates

BACKGROUND

The emergence of Clostridium difficile as a major nosocomial pathogen points to the need for safe, effective, and fast-acting environmental sporicides for infection prevention and control. Available and fast-acting sporicides are generally corrosive and unsafe for both humans and the environment.

METHODS

We evaluated chlorine bleach (500 and 5000 ppm) and a gel containing 4.5% of accelerated hydrogen peroxide against the spores of C difficile and its surrogates Bacillus subtilis and Clostridium sporogenes with contact times of 1, 5, and 10 minutes at 20°C ± 2°C using a quantitative carrier test (QCT-2), which is a standard (ASTME2197) of American Society for Testing and Materials International.

RESULTS

The gel and the higher level of bleach inactivated ≥6-log(10) of viable spores of all 3 types in 10 minutes but were unable to do so after 1 and 5 minutes. The lower level of bleach showed virtually no activity even after 10 minutes. The gel could keep the treated surface wet for the entire 10 minutes, whereas the bleach became visibly dry in approximately 4 minutes and needed reapplication.

CONCLUSION

The gel, with no off-gassing and designed especially for use on toilet bowls to allow for the required dwell time on vertical surfaces with one application, is a potential alternative to high levels of bleach.

Prevention of endemic healthcare-associated Clostridium difficile infection: reviewing the evidence

OBJECTIVES

Clostridium difficile is the most common infectious cause of healthcare-associated diarrhea. Because of the increasing incidence and severity of endemic C. difficile infection (CDI), interventions to prevent healthcare-associated CDI are essential. We undertook a systematic review of interventions to reduce healthcare-associated CDI.

METHODS

We searched multiple computerized databases, and manually searched for relevant articles to determine which interventions are useful in preventing CDI. Studies were required to be controlled in design and to report the incidence of endemic CDI as an outcome. Data on the patient population, intervention, study design, and outcomes were abstracted and reviewed using established criteria.

RESULTS

Few randomized controlled trials exist in the area of CDI prevention. The interventions with the greatest evidence for the prevention of CDI include antimicrobial stewardship, glove use, and disposable thermometers. Environmental decontamination also may decrease CDI rates, although the level of evidence is not as strong as for the other proven interventions. Treatment of asymptomatic carriage of C. difficile is not recommended. There is insufficient evidence to make a recommendation for or against the use of probiotics. In cases of known or suspected CDI, hand hygiene with soap and water is preferred over use of waterless alcohol hand rub. Many nonrandomized trials included in our analysis used multiple interventions concurrently, making the independent role of each preventive strategy difficult to determine. We chose to include only studies that focused on endemic CDI because studies of outbreaks have used multiple strategies, making it difficult to measure the relative efficacy of each strategy. Environmental disinfection and probiotics need to be studied further to evaluate their roles in the prevention of CDI. Although there have been no studies assessing the utility of isolation and cohorting for the prevention of endemic CDI specifically, it is a widely used intervention for containment of this and other similar multidrug-resistant pathogens.

CONCLUSIONS

Antimicrobial stewardship, glove use, hand hygiene, and disposable thermometers should be routinely used for the prevention of CDI. Environmental disinfection and probiotics should be studied further for their role in reducing CDI.

Spore-forming Bacilli and Clostridia in human disease

Many Gram-positive spore-forming bacteria in the Firmicute phylum are important members of the human commensal microbiota, which, in rare cases, cause opportunistic infections. Other spore-formers, however, have evolved to become dedicated pathogens that can cause a striking variety of diseases. Despite variations in disease presentation, the etiologic agent is often the spore, with bacterially produced toxins playing a central role in the pathophysiology of infection. This review will focus on the specific diseases caused by spores of the Clostridia and Bacilli.

Disease transmission model for community-associated Clostridium difficile infection

Participating researchers and public health personnel at a Canadian workshop in 2007, noted considerable gaps in current understanding of community-associated Clostridium difficile infection (CA-CDI), specifically infection sources and risk factors. A disease transmission model for CA-CDI was requested as an initial step towards a risk assessment, to analyse infection sources and risk factors, addressing priority research areas. The developed model contains eight infection states (susceptible, gastrointestinal exposure, colonized, diseased, deceased, clinically resolved colonized, relapse diseased, and cleared) and notes directional transfers between the states. Most published research used focused on hospital-associated C. difficile infection (HA-CDI) and further studies are needed to substantiate the use of HA-CDI knowledge in the transmission of CA-CDI. The aim was to provide a consistent framework for researchers, and provide a theoretical basis for future quantitative risk assessment of CA-CDI.

Treatment of Clostridium difficile-associated disease

Clostridium difficile infection is an increasing burden to the health care system, totaling more than $1 billion/year in the United States. Treatment of patients with C difficile infection with metronidazole or vancomycin reduces morbidity and mortality, although the number of patients that do not respond to metronidazole is increasing. Despite initial response rates of greater than 90%, 15%-30% of patients have a relapse in symptoms after successful initial therapy, usually in the first few weeks after treatment is discontinued. Failure to develop specific antibody response has recently been identified as a critical factor in recurrence. The review discusses the different management strategies for initial and recurrent symptomatic C difficile infections.

Clostridial typhlitis associated with topical antibiotic therapy in a Syrian hamster

A Syrian hamster that had been treated with topical antibiotic ointment for 10 days following injuries sustained during fighting was presented moribund. Postmortem and microscopic examinations revealed lesions consistent with clostridial typhlitis and enteritis. Anaerobic culture of caecal contents resulted in the isolation of two Clostridium species, and caecal contents contained Clostridium difficile enterotoxins. Based on these findings, a diagnosis of acute C. difficile enterotoxaemia was made. This report discusses the pathogenesis of C. difficile enterotoxaemia and the potential role of topical antibiotic ointment therapy in initiating the disease.

Infection control measures to limit the spread of Clostridium difficile

Clostridium difficile-associated diarrhoea (CDAD) presents mainly as a nosocomial infection, usually after antimicrobial therapy. Many outbreaks have been attributed to C. difficile, some due to a new hyper-virulent strain that may cause more severe disease and a worse patient outcome. As a result of CDAD, large numbers of C. difficile spores may be excreted by affected patients. Spores then survive for months in the environment; they cannot be destroyed by standard alcohol-based hand disinfection, and persist despite usual environmental cleaning agents. All these factors increase the risk of C. difficile transmission. Once CDAD is diagnosed in a patient, immediate implementation of appropriate infection control measures is mandatory in order to prevent further spread within the hospital. The quality and quantity of antibiotic prescribing should be reviewed to minimise the selective pressure for CDAD. This article provides a review of the literature that can be used for evidence-based guidelines to limit the spread of C. difficile. These include early diagnosis of CDAD, surveillance of CDAD cases, education of staff, appropriate use of isolation precautions, hand hygiene, protective clothing, environmental cleaning and cleaning of medical equipment, good antibiotic stewardship, and specific measures during outbreaks. Existing local protocols and practices for the control of C. difficile should be carefully reviewed and modified if necessary.

Clostridium difficile infection: emerging concepts and treatments

Clostridium difficile infection has become one of the most common causes of diarrhea in patients frequenting hospitals, skilled nursing facilities, and physicians' offices. Although the pathogenesis and clinical description were well elucidated three decades ago, cure during the initial episode now occurs in fewer than two thirds of patients exhibiting clinical illness. The past decade has brought a new strain with more toxin. Frequent relapses in elderly patients are now the norm rather than a rarity. This review is intended to update clinicians regarding diagnosis, infection control, and treatment, including treatment of the difficult-to-treat patient with multiple relapses of C. difficile infection.

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. This review evaluates the role of general ward ventilation to assess whether or not it affects the transmission of infection.

METHODS

A critical review was undertaken of guidelines in the United Kingdom and United States governing the design of ventilation systems for hospital wards and other multibed rooms. In addition, an analytical computational fluid dynamics (CFD) study was performed to evaluate the effectiveness of various ventilation strategies in removing airborne pathogens from ward spaces.

RESULTS

The CFD simulation showed the bioaerosol concentration in the study room to be substantially lower (2467 cfu/m(3)) when air was supplied and extracted through the ceiling compared with other simulated ventilations strategies, which achieved bioaerosol concentrations of 12487 and 10601 cfu/m(3), respectively.

CONCLUSIONS

There is a growing body of evidence that the aerial dispersion of some nosocomial pathogens can seed widespread environmental contamination, and that this may be contributing to the spread infection in hospital wards. Acinetobacter spp in particular appear to conform to this model, with numerous outbreaks attributed to aerial dissemination. This suggests that the clinical role of general ward ventilation may have been underestimated and that through improved ward ventilation, it may be possible to reduce environmental contamination and thus reduce nosocomial infection rates.

Treatment of Clostridium difficile infection

Recent outbreaks of Clostridium difficile infection (CDI) in North America have been due to a more virulent, possibly more resistant strain that causes more-severe disease, making prompt recognition of cases and optimal management of infection essential for a successful therapeutic outcome. Treatment algorithms are presented to help guide the management of patients with CDI. Metronidazole has been recommended as initial therapy since the late 1990s and continues to be the first choice for all but seriously ill patients and those with complicated or fulminant infections or multiple recurrences of CDI, for whom vancomycin is recommended. Other options for recurrent CDI, such as probiotics and currently available anion-exchange resins, have limited efficacy and are potentially harmful. Intravenous immunoglobulin may benefit patients with refractory, recurrent, or severe disease, but no controlled data are available. Two antimicrobials available in the United States for other indications, nitazoxanide and rifaximin, have been used successfully for CDI treatment but, like metronidazole, lack United States Food and Drug Administration approval for this indication. Experimental treatments currently in clinical development include a toxin-binding polymer, tolevamer; 2 poorly absorbed antimicrobials, OPT-80 (formerly known as Difimicin) and ramoplanin; monoclonal antibodies; and a C. difficile vaccine.

Historical perspectives on studies of Clostridium difficile and C. difficile infection

The initial period of studies on Clostridium difficile (published during 1978-1980) appeared to provide a nearly complete portfolio of criteria for diagnosing and treating C. difficile infection (CDI). The putative pathogenic role of C. difficile was established using Koch's postulates, risk factors were well-defined, use of a cell cytotoxicity assay as the diagnostic test provided accurate results, and treatment with oral vancomycin was highly effective and rapidly incorporated into practice. During the next 10 years, enzyme immunoassays (EIAs) were introduced as diagnostic tests and became the standard for most laboratories. This was not because EIAs were as good as the cell cytotoxicity assay; rather, EIAs were inexpensive and yielded results quickly. Similarly, metronidazole became the favored treatment because it was less expensive and quelled fears of colonization with vancomycin-resistant organisms, not because it was better than vancomycin therapy. Cephalosporins replaced clindamycin as the major inducers of CDI because they were so extensively used, rather than because they incurred the same risk. Some serious issues remained unresolved during this period: the major challenges were to determine ways to treat seriously ill patients for whom it was not possible to get vancomycin into the colon and to find methods that stop persistent relapses. These concerns persist today.

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. However previous studies have failed to isolate C. difficile from air in hospitals. In an attempt to clarify this issue we undertook a short controlled pilot study in an elderly care ward with the aim of culturing C. difficile from the air.

METHODS

In a survey undertaken during February (two days) 2006 and March (two days) 2007, air samples were collected using a portable cyclone sampler and surface samples collected using contact plates in a UK hospital. Sampling took place in a six bedded elderly care bay (Study) during February 2006 and in March 2007 both the study bay and a four bedded orthopaedic bay (Control). Particulate material from the air was collected in Ringer's solution, alcohol shocked and plated out in triplicate onto Brazier's CCEY agar without egg yolk, but supplemented with 5 mg/L of lysozyme. After incubation, the identity of isolates was confirmed by standard techniques. Ribotyping and REP-PCR fingerprinting were used to further characterise isolates.

RESULTS

On both days in February 2006, C. difficile was cultured from the air with 23 samples yielding the bacterium (mean counts 53 - 426 cfu/m3 of air). One representative isolate from each of these was characterized further. Of the 23 isolates, 22 were ribotype 001 and were indistinguishable on REP-PCR typing. C. difficile was not cultured from the air or surfaces of either hospital bay during the two days in March 2007.

CONCLUSION

This pilot study produced clear evidence of sporadic aerial dissemination of spores of a clone of C. difficile, a finding which may help to explain why CDAD is so persistent within hospitals and difficult to eradicate. Although preliminary, the findings reinforce concerns that current C. difficile control measures may be inadequate and suggest that improved ward ventilation may help to reduce the spread of CDAD in healthcare facilities.

Transcutaneous immunization with Clostridium difficile toxoid A induces systemic and mucosal immune responses and toxin A-neutralizing antibodies in mice

Clostridium difficile is the leading cause of nosocomial infectious diarrhea. C. difficile produces two toxins (A and B), and systemic and mucosal anti-toxin A antibodies prevent or limit C. difficile-associated diarrhea. To evaluate whether transcutaneous immunization with formalin-treated C. difficile toxin A (CDA) induces systemic and mucosal anti-CDA immune responses, we transcutaneously immunized three cohorts of mice with CDA with or without immunoadjuvantative cholera toxin (CT) on days 0, 14, 28, and 42. Mice transcutaneously immunized with CDA and CT developed prominent anti-CDA and anti-CT immunoglobulin G (IgG) and IgA responses in serum and anti-CDA and anti-CT IgA responses in stool. Sera from immunized mice were able to neutralize C. difficile toxin A activity in an in vitro cell culture assay. CDA itself demonstrated adjuvant activity and enhanced both serum and stool anti-CT IgA responses. Our results suggest that transcutaneous immunization with CDA toxoid may be a feasible immunization strategy against C. difficile, an important cause of morbidity and mortality against which current preventative strategies are failing.

The emergence ofClostridium difficileas a pathogen of food animals

Clostridium difficilecauses pseudomembranous colitis in humans, usually after disruption of the bowel flora by antibiotic therapy. Factors mediating the frank disease include the dose and toxigenicity of the colonizing strain, its ability to adhere to colonic epithelium, the concurrent presence of organisms that affect multiplication and toxin production or activity, and the susceptibility of the host. Toxins A (an enterotoxin) and B (a cytotoxin) play the major role in pathogenesis and the detection of toxins in gut contents is the gold standard for diagnosis. Disease in horses takes the form of often-fatal foal hemorrhagic enteritis. Nosocomial, antibiotic-associated, disease is increasingly common in adult horses. Enteric clinical signs are reported in ostriches, companion animals and recently calves.Clostridium difficilecolitis is now a common diagnosis in neonatal pigs in the USA and elsewhere. Clinical features include onset at 1–5 days of age, sometimes with dyspnea, mild abdominal distension and scrotal edema, and commonly with yellow, pasty diarrhea. There is mesocolonic edema grossly, with microscopic diffuse colitis, mucosal edema, crypt distension, epithelial necrosis and superficial mucosal erosion. Neutrophil infiltration of the lamina propria is common, and fibrin and numerous rod-shaped bacteria are observed on the surface. About two-thirds of litters and one-third of piglets will be affected (based upon positive toxin tests), although this appears to vary with the season. The case fatality rate is probably low if considering only direct effects ofC. difficileinfection. The significance of toxin-positive non-diarrheic pigs and the nature of the interaction of toxins A and B with enterocytes are unknown. Given the widespread occurrence of the disease, there is substantial effort to develop immunoprophylactic products.

An evaluation of patient area cleaning in 3 hospitals using a novel targeting methodology

BACKGROUND

Although environmental cleaning and disinfecting practices have become a cornerstone of patient care, assessment of actual compliance with such procedures has not been reported. Using a novel methodology, we developed a means to monitor directly such activities.

METHODS

A nontoxic target solution, which intensely fluoresces with a black light, was formulated to be inconspicuous yet readily removed by housekeeping products. Small volumes of material were confidentially applied to 12 target sites in patient rooms in 3 hospitals following terminal cleaning. The targets were reevaluated following terminal cleaning after several patients had occupied the room.

RESULTS

One hundred fifty-seven rooms and 1404 targets were evaluated. In the 3 hospitals studied, only 45%, 42%, and 56% of targets were removed by routine terminal cleaning/disinfecting activities. The frequency with which various individual sites were cleaned varied widely but was similar in all hospitals.

CONCLUSION

The use of a novel target compound to evaluate housekeeping practices confirmed high rates of cleaning of traditional sites but poor cleaning of many sites that have significant potential for harboring and transmitting microbial pathogens. This methodology has the potential for being used to evaluate objectively the cleaning/disinfecting activities in various health care settings.

Significant Absorption of Oral Vancomycin in a Patient with Clostridium difficile Colitis and Normal Renal Function

Orally-administered vancomycin is poorly absorbed in most patients, usually producing minimal or subtherapeutic serum concentrations. Bowel inflammation may enhance absorption of oral vancomycin, particularly in those with renal failure. A 77-year-old female with Clostridium difficile (C difficile) colitis and normal renal function was treated with high doses of oral vancomycin and achieved serum concentrations in the therapeutic range. To our knowledge, this is the first report of a patient with C difficile colitis and normal renal function to develop therapeutic serum concentrations following oral administration of vancomycin.

Clostridium difficile: An important pathogen of food animals

Human Clostridium difficile-associated disease (CDAD) is of unquestioned importance in humans, and has been a not-uncommon cause of enteric disease in horses, dogs, and ratites. Over the past 5 years, C. difficile has emerged as a major cause of neonatal enteritis in pigs. Piglets 1-7 days of age are affected, with gross lesions frequently including mesocolonic edema. Colonic contents may be pasty-to-watery and yellow, although some piglets are constipated or obstipated. Focal suppuration and segmental necrosis are seen on microscopic examination of cecal and colonic lamina propria, and exudation of neutrophils and fibrin into the lumen gives rise to the so-called volcano lesions. Results of one study revealed that more than one-third of piglets with enteritis were affected by C. difficile alone, while an additional quarter of affected piglets may have had mixed infections. C. difficile may be the most important uncontrolled cause of neonatal diarrhea in pigs.

Could hospital patients' hands constitute a missing link?

The relationship between contamination of patients' hands and transmission of healthcare-associated infection has received only limited attention, but may represent a previously overlooked but potentially significant link in the chain of infection. This paper aims critically to review the literature to determine whether this possible epidemiological relationship is worthy of further consideration. Studies that have investigated the microbiology or hand hygiene behaviours of patients and other groups are examined to establish their limitations and implications for future practice and research. Examples of healthcare-associated infections where improving patient hand hygiene may have a favourable impact on transmission, and how this might be achieved within the context of current UK health service initiatives, are discussed. It is recommended that systematic studies of the role of patients' hands in the chain of hospital infection should be undertaken.

Clostridium difficile: an update

Clostridium difficile causes a spectrum of diarrheal illness with the potential for major medical consequences. Although most cases respond quickly to treatment, C. difficile colitis may be severe and life threatening. Recurrent disease represents a particularly challenging problem.

Contamination, disinfection, and cross-colonization: are hospital surfaces reservoirs for nosocomial infection?

Despite documentation that the inanimate hospital environment (e.g., surfaces and medical equipment) becomes contaminated with nosocomial pathogens, the data that suggest that contaminated fomites lead to nosocomial infections do so indirectly. Pathogens for which there is more-compelling evidence of survival in environmental reservoirs include Clostridium difficile, vancomycin-resistant enterococci, and methicillin-resistant Staphylococcus aureus, and pathogens for which there is evidence of probable survival in environmental reservoirs include norovirus, influenza virus, severe acute respiratory syndrome-associated coronavirus, and Candida species. Strategies to reduce the rates of nosocomial infection with these pathogens should conform to established guidelines, with an emphasis on thorough environmental cleaning and use of Environmental Protection Agency-approved detergent-disinfectants.

Active and passive immunization against Clostridium difficile diarrhea and colitis

Clostridium difficile, a gram-positive bacterium, is the major cause of hospital-acquired infectious diarrhea and colitis in industrialized nations. C. difficile colonization results from antibiotic administration and subsequent loss of protection provided by intestinal flora. C. difficile induced-colitis is caused by the release of two exotoxins, toxin A and B. Host factors including advanced age, pre-existing severe illness and weakened immune defenses predispose individuals to symptomatic infection. The generation of antibody responses to toxin A through natural exposure is associated with protection from disease. In addition, an inability to acquire immunity to toxin A puts individuals at risk for recurrent and/or severe disease. Immunological approaches for the management of this disease are being developed which could reduce the reliance on antibiotics for treatment and allow for re-establishment of the natural barrier provided by an intact commensal flora. An active vaccine and various immunotherapeutic strategies under evaluation may prove to be effective against severe or relapsing C. difficile infection.

Favorable impact of a multidisciplinary antibiotic management program conducted during 7 years

OBJECTIVE

To evaluate the impact of an interventional multidisciplinary antibiotic management program on expenditures for antibiotics and on the incidence of nosocomial infections caused by Clostridium difficile and antibiotic-resistant pathogens during 7 years.

DESIGN

Prospective study with comparison with preintervention trends.

SETTING

University-affiliated teaching hospital.

PATIENTS

All adult inpatients.

INTERVENTION

A multidisciplinary antibiotic management program to minimize the inappropriate use of third-generation cephalosporins was implemented in 1991. Its impact was evaluated prospectively. The incidence of nosocomial C. difficile and resistant Enterobacteriaceae infections as well as the rate of vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) were compared with those of National Nosocomial Infections Surveillance System hospitals of similar size.

RESULTS

Following implementation of the program, there was a 22% decrease in the use of parenteral broad-spectrum antibiotics (P < .0001) despite a 15% increase in acuity of patient care during the following 7 years. Concomitantly, there was a significant (P = .002) decrease in nosocomial infections caused by C. difficile and a significant (P = .02) decrease in nosocomial infections caused by resistant Enterobacteriaceae. The program also appeared to have a favorable impact on VRE rates without a sustained impact on MRSA rates.

CONCLUSION

These results suggest that an ongoing multidisciplinary antibiotic management program may have a sustained beneficial impact on both expenditures for antibiotics and the incidence of nosocomial infection by C. difficile and resistant bacterial pathogens.

Clostridium difficile in a geriatric unit: a prospective epidemiological study employing a novel S-layer typing method

Clostridium difficile is the major identifiable cause of antibiotic-associated diarrhoea in the UK. The aim of this study was to employ traditional culture, toxin detection and a novel typing method to determine the level of C. difficile colonization and disease in a population of elderly patients and to investigate the association between strains in the patients and their environment. Three hundred and ninety patients between 62 and 101 years of age admitted to a geriatric unit in the Royal Victoria Hospital (RVH), Edinburgh, were investigated for the presence of C. difficile. C. difficile was cultured from 100 (26 %) patients using pre-reduced cycloserine-cefoxitin egg yolk agar, and toxin(s) was detected in the faeces of 34 of these patients using the Techlab ELISA test kit for the detection of C. difficile toxins A and/or B. Toxin(s) was detected in a further 18 patients from whom no C. difficile was detected in culture. Of the patients in whom C. difficile was detected, 49 % had diarrhoea, with the highest proportion of patients with diarrhoea being both culture- and toxin-positive for C. difficile. Environmental sampling of the patient environment yielded C. difficile from 14 % of samples. The organism was most frequently isolated from floors, sluice-rooms and toilet areas. The variation in the molecular mass of the C. difficile S-layer proteins was exploited as the basis of a novel typing method for C. difficile. Isolates from patients in the RVH were given a four-digit 'S-type' number based on their S-layer protein profile. A total of seven S-types were identified, with one type, toxigenic S-type 5236, accounting for 73 % of all clinical isolates and 91 % of environmental isolates.

Clinical correlation of toxin and common antigen enzyme immunoassay testing in patients with Clostridium difficile disease

OBJECTIVE

The aim of the present study was to assess the correlation of Triage Micro Clostridium difficile Panel and toxin B cytotoxicity assay with the clinical diagnosis of C. difficile diarrhea.

METHODS

The subjects evaluated were 98 patients with diarrhea for whom stool was submitted for testing for C. difficile. Clinical symptoms prompting evaluation, laboratory values, comorbid illness, and treatment outcomes that provided clinical insight into the etiology of the diarrhea were recorded. These data were then reviewed by two experienced clinical gastroenterologists who were blinded to the results of the Triage enzyme immunoassay and cytotoxin B assay. The final diagnosis of C. difficile diarrhea was based on the patient's clinical evaluation and symptoms, treatment, and subsequent outcome.

RESULTS

Of 98 patients evaluated, 33 were diagnosed with C. difficile diarrhea by clinical criteria. The toxin B assay displayed 88% sensitivity and 100% specificity and positive predictive value. The toxin A component of the Triage Panel displayed 45% sensitivity but 98% specificity and 94% positive predictive value. The common antigen had 97% sensitivity and 95% negative predictive value. Among the 45 patients with only a common antigen detected, the most common diagnoses for diarrhea were chemotherapy-related, antibiotic-related diarrhea, and graft versus host disease.

CONCLUSIONS

Our data show that both the Triage Micro C. difficile Panel and cytotoxin B for C. difficile have a high positive predictive value and negative predictive value for C. difficile diarrhea. The Triage Micro C. difficile Panel provides a reasonable alternative to the cytotoxin B assay in the assessment of clinically relevant C. difficile. The Triage Micro C. difficile Panel is less labor intensive and less expensive than cytotoxin B assay. The panel approach improves on the individual assay performances by increasing sensitivity and negative predictive value. When both common antigen and toxin A are positive, the likelihood of C. difficile diarrhea is high; conversely, when both results are negative, the likelihood of C. difficile diarrhea is low.

Gastrointestinal disorders and the critically ill. Clostridium difficile infection and pseudomembranous colitis

Clostridium difficile causes a spectrum of diseases ranging from diarrhoea to pseudomembranous colitis, primarily in the hospitalized elderly, although community-acquired infection is probably under-documented. Host factors are increasingly recognized as critical determinants of disease expression. Exposure to antibiotics, particularly those adversely affecting anaerobic gut flora, appears to create a niche which is exploited by C. difficile. Several retrospective and intervention studies have indicated that third-generation cephalosporins have a high propensity to induce C. difficile diarrhoea. Conversely, some broad-spectrum antibiotics, including ureidopenicillins (e.g. piperacillin-tazobactam) and ciprofloxacin, are less likely to induce C. difficile infection. Effective control of C. difficile in the hospital requires both antibiotic control and prevention of environmental seeding and bacterial spread. Epidemic C. difficile strains are widely distributed in the hospital environment, both as a cause and result of nosocomial diarrhoea. Current treatment options are antibiotic-based, which is less than ideal. Although many biotherapeutic approaches have been tried few have shown real benefit.

Clostridium difficile infections in animals with special reference to the horse. A review

In human medicine, Clostridium (C.) difficile is since many years a well-known cause of nosocomial diarrhea induced by antibiotic treatment. In horses, C. difficile was recently suggested as a possible enteric pathogen. The bacterium is associated with acute colitis in mature horses following treatment with antibiotics. C. difficile, and/or its cytotoxin, is also associated with acute colitis in mares when their foals are being treated with erythromycin and rifampicin for Rhodococcus equi pneumonia. The colitis can have resulted from an accidental ingestion of erythromycin by the mares. In an experimental study it was also demonstrated in mature horses that erythromycin can induce severe colitis associated with proliferation of C. difficile. A new interesting finding was that in healthy foals younger than 14 days, C. difficile was isolated from every third foal whereas older foals proved negative. In this paper the current state of knowledge of C. difficile infections in animals, especially in horses, is reviewed. A short description is given of the historical background of Clostridium difficile and the antibiotic-associated colitis and diarrhea caused by infection with this bacterium. The taxonomy of Clostridium difficile is described extensively. A summary is given of the diseases associated with clostridia infections in animals. Special attention is paid to the pathogenesis, epidemiology, clinical symptoms, laboratory diagnosis, and pathology of Clostridium difficile infections in horses. Finally, some other bacterial causes of colitis in horses are discussed shortly.