A quantitative study of the survival of two species of Candida on porous and non-porous environmental surfaces and hands

How long do nosocomial pathogens persist on inanimate surfaces? A scoping review

Healthcare hygiene plays a crucial role in the prevention of healthcare-associated infections. Patients admitted to a room where the previous occupant had a multi-drug-resistant bacterial infection are at an increased risk of colonization and infection with the same organism. A 2006 systematic review by Kramer et al. found that certain pathogens can survive for months on dry surfaces. The aim of this review is to update Kramer et al.'s previous review and provide contemporary data on the survival of pathogens relevant to the healthcare environment. We systematically searched Ovid MEDLINE, CINAHL and Scopus databases for studies that described the survival time of common nosocomial pathogens in the environment. Pathogens included in the review were bacterial, viral, and fungal. Studies were independently screened against predetermined inclusion/exclusion criteria by two researchers. Conflicts were resolved by one of two senior researchers. A spreadsheet was developed for the data extraction. The search identified 1736 studies. Following removal of duplicates and application of the search criteria, the synthesis of results from 62 included studies were included. 117 organisms were reported. The longest surviving organism reported was Klebsiella pneumoniae which was found to have persisted for 600 days. Common pathogens of concern to infection prevention and control, can survive or persist on inanimate surfaces for months. This data supports the need for a risk-based approach to cleaning and disinfection practices, accompanied by appropriate training, audit and feedback which are proven to be effective when adopted in a 'bundle' approach.

In vitro activity of sanitizers against mono- and polymicrobial biofilms of C. parapsilosis and S. aureus

The emergence of disinfectant-resistant microorganisms poses a significant threat to public health. These resilient pathogens can survive and thrive in hospital settings despite routine disinfection practices, leading to persistent infections and the potential for outbreaks. In this study, we investigated the impact of 11 different commercial sanitizers at various concentrations and exposure times on biofilms consisting of clinical and nosocomial environmental isolates of Candida parapsilosis and Staphylococcus aureus. Among the sanitizers tested, 0.5% and 2.0% chlorhexidine (CLX), 10% polyvinyl pyrrolidone (PVP-I), a disinfectant based on quaternary ammonium compound (QAC), 2% glutaraldehyde, and 0.55% orthophthalaldehyde (OPA) demonstrated efficacy against both C. parapsilosis and S. aureus in monospecies and mixed biofilms. Analysis showed that 0.5% CLX and 10% PVP-I had fungicidal and bactericidal activity against all biofilms. However, the sanitizer based on QAC and 0.55% OPA proved to be bacteriostatic and fungicidal against both monospecies and mixed biofilms. In mixed biofilms, despite the last four sanitizers exerting fungicidal action, the reduction of fungal cells was approximately 4 log10 CFU/mL compared to monospecies biofilms, showing that the interaction provided more resistance of the yeast to the sanitizer. Formation of mixed biofilms in hospital settings can create an ecological niche that enhances the survival of pathogens against routine sanitization procedures. Therefore, effective sanitization practices, including regular cleaning with effective sanitizers, should be implemented to prevent C. parapsilosis/S. aureus biofilm formation in healthcare settings.

Textiles as fomites in the healthcare system

Nosocomial infections or healthcare-associated infections (HAIs) are acquired under medical care in healthcare facilities. In hospital environments, the transmission of infectious diseases through textiles such as white coats, bed linen, curtains, and towels are well documented. Textile hygiene and infection control measures have become more important in recent years due to the growing concerns about textiles as fomites in healthcare settings. However, systematic research in this area is lacking; the factors contributing to the transmission of infections through textiles needs to be better understood. The review aims to critically explore textiles as contaminants in healthcare systems, and to identify potential risks they may pose to patients and healthcare workers. It delineates different factors affecting bacterial adherence on fabrics, such as surface properties of bacteria and fabrics, and environmental factors. It also identifies areas that require further research to reduce the risk of HAIs and improve textile hygiene practices. Finally, the review elaborates on the strategies currently employed, and those that can be employed to limit the spread of nosocomial infections through fabrics. Implementing textile hygiene practices effectively in healthcare facilities requires a thorough analysis of factors affecting fabric-microbiome interactions, followed by designing newer fabrics that discourage pathogen load. KEY POINTS: • Healthcare textiles act as a potential reservoir of nosocomial pathogens • Survival of pathogens is affected by surface properties of fabric and bacteria • Guidelines required for fabrics that discourage microbial load, for hospital use.

Ozone Efficacy for the Disinfection of Ambulances Used to Transport Patients during the COVID-19 Pandemic in Peru

We assessed the disinfection efficacy of an ozone generator prototype in ambulances used to transport patients with coronavirus disease (COVID-19). This research consisted of three stages: in vitro tests using microbial indicators, such as Candida albicans, Escherichia coli, Staphylococcus aureus and Salmonella phage, which were experimentally inoculated onto polystyrene crystal surfaces within a 23 m³ enclosure. They were then exposed to ozone at a 25 ppm concentration using the ozone generator (Tecnofood SAC) portable prototype, and the decimal reduction time (D) was estimated for each indicator. The second stage involved the experimental inoculation of the same microbial indicators on a variety of surfaces inside conventional ambulances. The third stage consisted of exploratory field testing in ambulances used to transport patients with suspected COVID-19. During the second and third stages, samples were collected by swabbing different surfaces before and after 25 ppm ozonisation for 30 min. Results suggested that ozone was most effective on Candida albicans (D = 2.65 min), followed by Escherichia coli (D = 3.14 min), Salmonella phage (D = 5.01 min) and Staphylococcus aureus (D = 5.40 min). Up to 5% of the microbes survived following ozonisation of conventional ambulances. Of the 126 surface samples collected from ambulances transporting patients with COVID-19, 7 were positive (5.6%) for SARS-related coronavirus as determined on reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Ozone exposure from the ozone generator prototype inside ambulances at a concentration of 25 ppm for 30 min can eliminate gram positive and negative bacteria, yeasts, and viruses.

Microbial adherence on vacuum-formed retainers with different surface roughness as constructed from conventional stone models and 3D printed models: a randomized controlled clinical trial

OBJECTIVE

This single center parallel, randomized controlled trial aimed to determine the propensity of microbial adherence on vacuum-formed retainers (VFRs) with different surface roughness imprints.

MATERIALS AND METHODS

Thirty-six patients debonded from fixed appliances at a teaching institution were allocated by block randomization stratified for gender to three groups [VFRs fabricated on conventional, fused deposition modeling (FDM) or stereolithography apparatus (SLA) working models]. Participants wore the VFRs for three months full-time followed by three months part-time. VFRs were collected after each follow-up for Streptococcus and yeast counts. Surface roughness was measured indirectly on the working models using a 3D optical surface texture analyzer. Blinding was not feasible due to appliance appearance. The trial was registered [NCT03844425 ( ClinicalTrials.gov )] and funded by the Universiti Malaya Dental Postgraduate Research Grant (DPRG/14/19).

RESULTS

Thirty participants (eleven conventional, ten FDM, and nine SLA) were analyzed after six dropped out. No harms were reported. Microbial counts between the groups were not significantly different. There were more microbes in the lower VFRs than upper VFRs (total count: p<0.05; effect size, 0.5 during full-time wear and 0.4 during part-time wear). SLA had significantly (p<0.05) smoother surface than FDM (effect size, 0.3) and conventional models (effect size, 0.5). Microbial adherence was not associated with working model surface roughness.

CONCLUSION

Microbial adherence on VFRs was not influenced by degree of surface roughness imprints from working models.

CLINICAL RELEVANCE

3D printed models can be used to make VFRs. Lower VFRs tended to accumulate oral microbes, potentially increasing the oral health risk in the lower arch.

Evolution of Fluconazole Resistance Mechanisms and Clonal Types of Candida parapsilosis Isolates from a Tertiary Care Hospital in South Korea

We investigated the evolution of fluconazole resistance mechanisms and clonal types of Candida parapsilosis isolates from a tertiary care hospital in South Korea. A total of 45 clinical isolates, including 42 collected between 2017 and 2021 and 3 collected between 2012 and 2013, were subjected to antifungal susceptibility testing, sequencing of fluconazole resistance genes (ERG11, CDR1, TAC1, and MRR1), and microsatellite typing. Twenty-two isolates carried Y132F (n = 21; fluconazole MIC = 2 to >256 mg/L) or Y132F+R398I (n = 1; fluconazole MIC = 64 mg/L) in ERG11 and four isolates harbored N1132D in CDR1 (fluconazole MIC = 16 to 64 mg/L). All 21 Y132F isolates exhibited similar microsatellite profiles and formed a distinct group in the dendrogram. All four N1132D isolates displayed identical microsatellite profiles. Fluconazole MIC values of the Y132F isolates varied depending on their MRR1 mutation status (number of isolates, year of isolation, and MIC): K177N (n = 8, 2012 to 2020, 2 to 8 mg/L); K177N + heterozygous G982R (n = 1, 2017, 64 mg/L); K177N + heterozygous S614P (n = 2, 2019 to 2020, 16 mg/L); and K177N + homozygous S614P (n = 10, 2020 to 2021, 64 to > 256 mg/L). Our study revealed that Y132F in ERG11 and N1132D in CDR1 were the major mechanisms of fluconazole resistance in C. parapsilosis isolates. Furthermore, our results suggested that the clonal evolution of Y132F isolates persisting and spreading in hospital settings for several years occurred with the acquisition of heterozygous or homozygous MRR1 mutations associated with a gradual increase in fluconazole resistance.

Inanimate Surfaces as a Source of Hospital Infections Caused by Fungi, Bacteria and Viruses with Particular Emphasis on SARS-CoV-2

The carriers of nosocomial infections are the hands of medical personnel and inanimate surfaces. Both hands and surfaces may be contaminated as a result of contact with the patient, their body fluids, and touching contaminated surfaces in the patient’s surroundings. Visually clean inanimate surfaces are an important source of pathogens. Microorganisms have properties thanks to which they can survive in unfavorable conditions, from a few days to several months. Bacteria, viruses and fungi are able to transmit from inanimate surfaces to the skin of the patient and the medical staff. These pathogens include SARS-CoV-2, which can survive on various types of inanimate surfaces, being a potential source of infection. By following the recommendations related to washing and disinfecting hands and surfaces, and using appropriate washing and disinfecting agents with a broad biocidal spectrum, high material compatibility and the shortest duration of action, we contribute to breaking the chain of nosocomial infections.

BioMateriOME: To understand microbe-material interactions within sustainable, living architectures

BioMateriOME evolved from a prototyping process which was informed from discussions between a team of designers, architects and microbiologists, when considering constructing with biomaterials or human cohabitation with novel living materials in the built environment. The prototype has two elements (i) BioMateriOME-Public (BMP), an interactive public materials library, and (ii) BioMateriOME-eXperimental (BMX), a replicated materials library for rigorous microbiome experimentation. The prototype was installed into the OME, a unique experimental living house, in order to (1) gain insights into society's perceptions of living materials, and (2) perform a comparative analysis of indoor surface microbiome development on novel biomaterials in contrast to conventional indoor surfaces, respectively. This review summarizes the BioMateriOME prototype and its use as a tool in combining microbiology, design, architecture and social science. The use of microbiology and biological components in the fabrication of biomaterials is provided, together with an appreciation of the microbial communities common to conventional indoor surfaces, and how these communities may change in response to the implementation of living materials in our homes. Societal perceptions of microbiomes and biomaterials, are considered within the framework of healthy architecture. Finally, features of architectural design with microbes in mind are introduced, with the possibility of codifying microbial surveillance into design and construction benchmarks, standards and regulations toward healthier buildings and their occupants.

Evidence Map and Systematic Review of Disinfection Efficacy on Environmental Surfaces in Healthcare Facilities

Healthcare-associated infections (HAIs) contribute to patient morbidity and mortality with an estimated 1.7 million infections and 99,000 deaths costing USD $28-34 billion annually in the United States alone. There is little understanding as to if current environmental surface disinfection practices reduce pathogen load, and subsequently HAIs, in critical care settings. This evidence map includes a systematic review on the efficacy of disinfecting environmental surfaces in healthcare facilities. We screened 17,064 abstracts, 635 full texts, and included 181 articles for data extraction and study quality assessment. We reviewed ten disinfectant types and compared disinfectants with respect to study design, outcome organism, and fourteen indictors of study quality. We found important areas for improvement and gaps in the research related to study design, implementation, and analysis. Implementation of disinfection, a determinant of disinfection outcomes, was not measured in most studies and few studies assessed fungi or viruses. Assessing and comparing disinfection efficacy was impeded by study heterogeneity; however, we catalogued the outcomes and results for each disinfection type. We concluded that guidelines for disinfectant use are primarily based on laboratory data rather than a systematic review of in situ disinfection efficacy. It is critically important for practitioners and researchers to consider system-level efficacy and not just the efficacy of the disinfectant.

Microbial Air Quality in Healthcare Facilities

There is increasing evidence that indoor air quality and contaminated surfaces provide an important potential source for transmission of pathogens in hospitals. Airborne hospital microorganisms are apparently harmless to healthy people. Nevertheless, healthcare settings are characterized by different environmental critical conditions and high infective risk, mainly due to the compromised immunologic conditions of the patients that make them more vulnerable to infections. Thus, spread, survival and persistence of microbial communities are important factors in hospital environments affecting health of inpatients as well as of medical and nursing staff. In this paper, airborne and aerosolized microorganisms and their presence in hospital environments are taken into consideration, and the factors that collectively contribute to defining the infection risk in these facilities are illustrated.

Persistence of Pathogens on Inanimate Surfaces: A Narrative Review

For the prevention of infectious diseases, knowledge about transmission routes is essential. In addition to respiratory, fecal-oral, and sexual transmission, the transfer of pathogens via surfaces plays a vital role for human pathogenic infections-especially nosocomial pathogens. Therefore, information about the survival of pathogens on surfaces can have direct implications on clinical measures, including hygiene guidelines and disinfection strategies. In this review, we reviewed the existing literature regarding viral, bacterial, and fungal persistence on inanimate surfaces. In particular, the current knowledge of the survival time and conditions of clinically relevant pathogens is summarized. While many pathogens persist only for hours, common nosocomial pathogens can survive for days to weeks under laboratory conditions and thereby potentially form a continuous source of transmission if no adequate inactivation procedures are performed.

How long can nosocomial pathogens survive on textiles? A systematic review

Aims: Healthcare-associated infections linked to contaminated textiles are rare but underline their potential role as a source for transmission. The aim of the review was to summarize the experimental evidence on the survival and persistence of the different types of nosocomial pathogens on textiles.

Methods: A literature search was performed on MedLine. Original data on the survival of bacteria, mycobacteria, and fungi and persistence of viruses on textiles were evaluated.

Results: The survival of bacteria at room temperature was the longest on polyester (up to 206 days), whereas it was up to 90 days for some species on cotton and mixed fibers. Only low inocula of 100 CFU were found on all types of textiles with a short survival time of ≤3 days. Most bacterial species survived better at elevated air humidity. The infectivity of viruses on textiles is lost much faster at room temperature, typically within 2–4 weeks.

Conclusions: Contaminated textiles or fabrics may be a source of transmission for weeks. The presence of pathogens on the coats of healthcare workers is associated with the presence of pathogens on their hands, demonstrating the relevance of textile contamination in patient care.

Quantitative Analysis of Selected Microorganisms Present at Various Sites in a Prosthetics Clinic and Dental Laboratory during Complete Denture Fabrication

Background: Contamination with oral commensals and pathogenic microorganisms, and cross contamination between clinic and laboratory can occur. The amount of contamination has not been determined. Methods: Samples from different clinical and laboratory stages before and after disinfection (17 sites, 10 samples per stage) were collected. Laboratory surfaces and equipment were swabbed for 10 days (11 sites). Swabs were cultured for total mixed flora, Streptococci, Lactobacilli, Staphylococcus aureus, aerobic Gram-negative bacteria (AGNB) and Candida. Knowledge of infection control among staff and students was assessed. Results: Clinic: In total, 30-40% of the samples overall were contaminated with mixed flora and Streptococci of >100 cfu/swab; >100 cfu of AGNB and Candida were present on 6% and 1% of samples; 2% contained <100 cfu of S. aureus. Laboratory: In total, 17-48% of the samples overall were contaminated with mixed flora and Streptococci of >100 cfu/swab; >100 cfu of AGNB were present on 11% of samples; none contained >100 cfu of Candida. Disinfection significantly reduced the level of all organisms. Knowledge of infection control was sufficient, but compliance was poor. Conclusion: Although the count of mixed flora was high, potential pathogens such as S. aureus and Candida were low. In immunocompromised patients, this can become a problem.

Specific antibacterial activity of copper alloy touch surfaces in five long-term care facilities for older adults

BACKGROUND

Pathogens involved in healthcare-associated infections can quickly spread in the environment, particularly to frequently touched surfaces, which can be reservoirs for pathogens.

AIM

The purpose of this study was to investigate naturally occurring bacterial contamination on touch surfaces in five French long-term care facilities and to compare bacterial populations recovered from copper and control surfaces.

METHODS

More than 1300 surfaces were sampled. The collected bacteria were identified to obtain a global view of the cultivable bacterial populations colonizing touch surfaces. Haemolytic colonies and putative pathogens were also screened using specific agar plates and then identified with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. In total, more than 3400 colonies were analysed.

FINDINGS

Staphylococcus and Micrococcus were the two predominant genera present on touch surfaces, respectively occurring on 51.8% and 48.0% of control surfaces. In these facilities with relatively low bioburden, copper surfaces efficiently reduced the occurrence frequencies of three genera: Staphylococcus, Streptococcus and Roseomonas. Pathogenic species such as Staphylococcus aureus, Enterococcus faecalis and E. faecium were observed in very few samples. In addition, meticillin-resistant S. aureus was observed on five control surfaces and one copper surface.

CONCLUSION

Contamination of healthcare facilities touch surfaces can be the source for the spread of bacteria through the institution. This in situ study shows that the frequency of the contamination as well as the specific bacterial population bioburden is reduced on copper alloy surfaces.

Yeast Biofilm as a Bridge Between Medical and Environmental Microbiology Across Different Detection Techniques

Medical and environmental microbiology have two distinct, although very short, histories stemming, the first from the pioneering works of Sommelweiss, Pasteur, Lister and Koch, the second mainly from the studies of Bejerink and Winogradsky. These two branches of microbiology evolved and specialized separately producing distinct communities and evolving rather different approaches and techniques. The evidence accumulated in recent decades indicate that indeed most of the medically relevant microorganisms have a short circulation within the nosocomial environment and a larger one involving the external, i.e. non-nosocomial, and the hospital environments. This evidence suggests that the differences between approaches should yield to a convergent approach aimed at solving the increasing problem represented by infectious diseases for the increasingly less resistant human communities. Microbial biofilm is one of the major systems used by these microbes to resist the harsh conditions of the natural and anthropic environment, and the even worse ones related to medical settings. This paper presents a brief outline of the converging interest of both environmental and medical microbiology toward a better understanding of microbial biofilm and of the various innovative techniques that can be employed to characterize, in a timely and quantitative manner, these complex structures. Among these, micro-Raman along with micro-Brillouin offer high hopes of describing biofilms both at the subcellular and supercellular level, with the possibility of characterizing the various landscapes of the different biofilms. The possibility of adding a taxonomic identification of the cells comprising the biofilm is a complex aspect presenting several technical issues that will require further studies in the years to come.

Survival, Persistence, and Isolation of the Emerging Multidrug-Resistant Pathogenic Yeast Candida auris on a Plastic Health Care Surface

The emerging multidrug-resistant pathogenic yeast Candida auris represents a serious threat to global health. Unlike most other Candida species, this organism appears to be commonly transmitted within health care facilities and causes health care-associated outbreaks. To better understand the epidemiology of this emerging pathogen, we investigated the ability of C. auris to persist on plastic surfaces common in health care settings compared with that of Candida parapsilosis, a species known to colonize the skin and plastics. Specifically, we compiled comparative and quantitative data essential to understanding the vehicles of spread and the ability of both species to survive and persist on plastic surfaces under controlled conditions (25°C and 57% relative humidity), such as those found in health care settings. When a test suspension of 10⁴ cells was applied and dried on plastic surfaces, C. auris remained viable for at least 14 days and C. parapsilosis for at least 28 days, as measured by CFU. However, survival measured by esterase activity was higher for C. auris than C. parapsilosis throughout the 28-day study. Given the notable length of time Candida species survive and persist outside their host, we developed methods to more effectively culture C. auris from patients and their environment. Using our enrichment protocol, public health laboratories and researchers can now readily isolate C. auris from complex microbial communities (such as patient skin, nasopharynx, and stool) as well as environmental biofilms, in order to better understand and prevent C. auris colonization and transmission.

Antimicrobial Efficacy of Laundry Detergents with Regard to Time and Temperature in Domestic Washing Machines

In times of low-temperature washing, laundry hygiene gains importance, as microbial contaminations on textiles can cause infection transmission and malodour formation. This study systematically investigated the antimicrobial effect of laundry detergents (solid and liquid market detergents) with regard to time and temperature in domestic washing machines. To evaluate the microbial reduction, cotton swatches contaminated with Staph. aureus, Ent. hirae, Ps. aeruginosa, C. albicans and T. mentagrophytes were washed at 20 to 60 °C, varying the washing time, with and without detergent. All tested washing factors affected the antimicrobial effect of to a varying extend, depending on the germ. The used solid market detergent containing activated oxygen bleach provided a way to achieve high microbial reductions in low temperature washing.

What Have We Learned about the Microbiomes of Indoor Environments?

The advent and application of high-throughput molecular techniques for analyzing microbial communities in the indoor environment have led to illuminating findings and are beginning to change the way we think about human health in relation to the built environment. Here I review recent studies on the microbiology of the built environment, organize their findings into 12 major thematic categories, and comment on how these studies have or have not advanced knowledge in each area beyond what we already knew from over 100 years of applying culture-based methods to building samples.

The advent and application of high-throughput molecular techniques for analyzing microbial communities in the indoor environment have led to illuminating findings and are beginning to change the way we think about human health in relation to the built environment. Here I review recent studies on the microbiology of the built environment, organize their findings into 12 major thematic categories, and comment on how these studies have or have not advanced knowledge in each area beyond what we already knew from over 100 years of applying culture-based methods to building samples. I propose that while we have added tremendous complexity to the rich existing knowledge base, the practical implications of this added complexity remain somewhat elusive. It remains to be seen how this new knowledge base will change how we design, build, and operate buildings. Much more research is needed to better understand the complexity with which indoor microbiomes may affect human health in both positive and negative ways.

What Have We Learned about the Microbiomes of Indoor Environments?

The advent and application of high-throughput molecular techniques for analyzing microbial communities in the indoor environment have led to illuminating findings and are beginning to change the way we think about human health in relation to the built environment. Here I review recent studies on the microbiology of the built environment, organize their findings into 12 major thematic categories, and comment on how these studies have or have not advanced knowledge in each area beyond what we already knew from over 100 years of applying culture-based methods to building samples. I propose that while we have added tremendous complexity to the rich existing knowledge base, the practical implications of this added complexity remain somewhat elusive. It remains to be seen how this new knowledge base will change how we design, build, and operate buildings. Much more research is needed to better understand the complexity with which indoor microbiomes may affect human health in both positive and negative ways.

Inactivation of bacteria on surfaces by sprayed slightly acidic hypochlorous acid water: in vitro experiments

The capacity of slightly acidic hypochlorous acid water (SAHW), in both liquid and spray form, to inactivate bacteria was evaluated as a potential candidate for biosecurity enhancement in poultry production. SAHW (containing 50 or 100 ppm chlorine, pH 6) was able to inactivate Escherichia coli and Salmonella Infantis in liquid to below detectable levels (≤2.6 log10 CFU/ml) within 5 sec of exposure. In addition, SAHW antibacterial capacity was evaluated by spraying it using a nebulizer into a box containing these bacteria, which were present on the surfaces of glass plates and rayon sheets. SAHW was able to inactivate both bacterial species on the glass plates (dry condition) and rayon sheets within 5 min spraying and 5 min contact times, with the exception of 50 ppm SAHW on the rayon sheets. Furthermore, a corrosivity test determined that SAHW does not corrode metallic objects, even at the longest exposure times (83 days). Our findings demonstrate that SAHW is a good candidate for biosecurity enhancement in the poultry industry. Spraying it on the surfaces of objects, eggshells, egg incubators and transport cages could reduce the chances of contamination and disease transmission. These results augment previous findings demonstrating the competence of SAHW as an anti-viral disinfectant.

Analysis of clinical and environmental Candida parapsilosis isolates by microsatellite genotyping--a tool for hospital infection surveillance

Candida parapsilosis emerged as an important opportunistic pathogen, causing candidaemia worldwide. Nosocomial outbreaks triggered by this species have been frequently described, particularly in cancer patients. For a better understanding of its epidemiology, several typing methods are used and microsatellite analysis has been reported as highly discriminant. The main objective of this work was to study C. parapsilosis isolates by application of microsatellite genotyping to distinguish epidemiologically related strains, compare clinical and environmental isolates and determine possible routes of dispersion of the isolates in the hospital setting. A total of 129 C. parapsilosis isolates from different origins, including hospital environment and hands of healthcare workers, were genotyped using four microsatellite markers. The isolates were recovered from different health institutions. Analysis of C. parapsilosis isolates from hospital environment showed great genotypic diversity; however, the same or very similar genotypes were also found. The same multilocus genotype was shared by isolates recovered from the hand of a healthcare worker, from the hospital environment and from patients of the same healthcare institution, suggesting that these could be possible routes of transmission and that infections due to C. parapsilosis may be mainly related with exogenous transmission to the patient. Examination of sequential isolates from the same patients showed that colonizing and bloodstream isolates had the same multilocus genotype in the majority of cases. We demonstrate that this typing method is able to distinguish clonal clusters from genetically unrelated genotypes and can be a valuable tool to support epidemiologic investigations in the hospital setting.

Persistence of nosocomial pathogens on various fabrics

OBJECTIVE

Fabrics can become contaminated with high numbers of microorganisms that may be pathogenic to patients in a hospital setting and can play an important role in the chain of infection. The aim of this study was to investigate the survival of several clinical bacterial and fungal isolates on several fabrics commonly used in hospitals.

MATERIALS AND METHODS

Bacterial and fungal survival was tested on the following materials, each of which are commonly used in our hospital: 100% smooth cotton, 60% cotton-40% polyester, 100% wool and 100% silk. One isolate each of Candida albicans, Candida tropicalis, Candida krusei, Candida glabrata, Candida parapsilosis, Geotrichum candidum, Aspergillus fumigatus, Cryptococcus neoformans, vancomycin resistant Enterococcus faecium (VRE, methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase (ESBL) positive Escherichia coli, inducible beta-lactamase (IBL) positive Pseudomonas aeruginosa, IBL-positive Acinetobacter baumannii and Stenotrophomonas maltophilia were used to contaminate fabrics. The survival of these microorganisms was studied by testing the fabric swatches for microbial growth.

RESULTS

The median survival times for all the tested bacteria and fungi were as follows: 26 days on cotton, 26.5 days on cotton-polyester, 28 days on silk, and 30 days on wool. Among the bacterial species tested, E. faecium had the longest survival time on cotton-polyester fabrics. For the fungal isolates, it was observed that C. tropicalis and C. krusei survived for the shortest amount of time on cotton fabrics in the present study.

CONCLUSION

This survival data indicate that pathogenic microorganisms can survive from days to months on commonly used hospital fabrics. These findings indicate that current recommendations for the proper disinfection or sterilization of fabrics used in hospitals should be followed to minimize cross-contamination and prevent nosocomial infections.

Clinical and tree hollow populations of human pathogenic yeast in Hamilton, Ontario, Canada are different

Yeast are among the most frequent pathogens in humans. The dominant yeast causing human infections belong to the genus Candida and Candida albicans is the most frequently isolated species. However, several non-C. albicans species are becoming increasingly common in patients worldwide. The relationships between yeast in humans and the natural environments remain poorly understood. Furthermore, it is often difficult to identify or exclude the origins of disease-causing yeast from specific environmental reservoirs. In this study, we compared the yeast isolates from tree hollows and from clinics in Hamilton, Ontario, Canada. Our surveys and analyses showed significant differences in yeast species composition, in their temporal dynamics, and in yeast genotypes between isolates from tree hollows and hospitals. Our results are inconsistent with the hypothesis that yeast from trees constitute a significant source of pathogenic yeast in humans in this region. Similarly, the yeast in humans and clinics do not appear to contribute to yeast in tree hollows.

Candida albicans and non-C. albicans Candida species: comparison of biofilm production and metabolic activity in biofilms, and putative virulence properties of isolates from hospital environments and infections

Candida albicans and, more recently, non-C. albicans Candida spp. are considered the most frequent fungi in hospitals. This study analyzed Candida spp. isolates and compared the frequency of different species, that is, C. albicans and non-C. albicans Candida spp., and the origins of isolates, that is, from hospital environments or infections. Yeast virulence factors were evaluated based on biofilm production and metabolic activity. Hemolysin production and the antifungal susceptibility profiles of isolates were also evaluated. Candida spp. were highly prevalent in samples collected from hospital environments, which may provide a reservoir for continuous infections with these yeasts. There were no differences in the biofilm productivity levels and metabolic activities of the environmental and clinical isolates, although the metabolic activities of non-C. albicans Candida spp. biofilms were greater than those of the C. albicans biofilms (p < 0.05). Clinical samples had higher hemolysin production (p < 0.05) and lower susceptibility to fluconazole (p < 0.05). Non-C. albicans Candida spp. predominated in samples collected from hospital environments and infections (p < 0.05). These species had a lower susceptibility to fluconazole and amphotericin B, and their biofilms had higher metabolic activities than those produced by C. albicans, which may explain the increased incidence of fungal infections with these yeasts during recent years.

The influence of different types of fixed orthodontic appliance on the growth and adherence of microorganisms (in vitro study)

Orthodontic appliances serve as different impact zones and modify microbial adherence and colonization, acting as foreign reserves and possible sources of infection. This study was conducted to investigate the effect of different types of fixed orthodontic appliances on the growth and adherence of microorganisms in oral flora which are Streptococcus mutans (S. mutans) and Candida albicans. Sixty-four of four different fixed orthodontic appliance-samples were used, divided into four groups of sixteen. Type I: Sapphire brackets- Coated wires, type II: Sapphire brackets- Stainless steel wires, type III: Stainless steel brackets- Coated wires and type IV: Stainless steel brackets- Stainless steel wires. Oral strains of S. mutans and Candida albicans were studied in the present study using biochemical test then microbial suspensions were prepared to do the tests of each microorganism including the antimicrobial effects of different appliance-samples on the growth of microorganisms and their adhesion tests. The results showed significant differences between the different appliances in terms of inhibition zone formation (P<0.001). The adhesion test, which is classified into low, medium and high, showed the adhesion of S. mutans, is low with type I and II, medium with type III and high with type IV, whereas the adhesion of Candida albicans is medium with both type I and II and high with both type III and IV with high significant differences (P<0.001). Appliance with high esthetic appearance, sapphire brackets and coated arch wire, showed the least adherence of S. mutans and Candida albicans in comparison to other appliances with less esthetic and more metal components.

Key words:Orthodontic appliance, Adherence, Streptococcus mutans, Candida albicans.

Temperature and humidity influences on inactivation kinetics of enteric viruses on surfaces

Norovirus (NoV) and hepatitis A virus (HAV) are pathogenic enteric viruses responsible for public health concerns worldwide. The viral transmission occurs through fecally contaminated food, water, fomites, or direct contact. However, the difficulty in cultivating these viruses makes it a challenge to characterize the resistance to various environmental stresses. In this study, we characterized the inactivation rates of murine norovirus (MNV), MS2, and HAV on either lacquer coating rubber tree wood or stainless steel under different temperature and relative humidity (RH) conditions. The viruses were analyzed at temperatures of 15 °C, 25 °C, 32 °C, and 40 °C and at RHs of 30%, 50%, and 70% for 30 days. Overall, they survived significantly longer on wood than on steel at lower temperature (P < 0.05). The inactivation rate of MS2 and MNV increased at higher RH levels, whereas HAV survived the best at a medium RH level (50%). The effect of RH was significant only for MS2 (P < 0.05). MS2 persisted longest under all of the environmental conditions examined. Both a linear and a nonlinear Weibull model were used to describe the viral inactivation data in this study. The data produced a better fit to the survival curves that were predicted by the Weibull model.

Adherence of Streptococcus mutans and Candida albicans to different bracket materials

Objective:

To quantify the adherence of Streptococcus mutans and Candida albicans on brackets made of stainless steel, plastic, ceramic, titanium, and gold, and to evaluate the various sites of adherence of these microorganisms with scanning electron microscopy (SEM).

Materials and Methods:

Brackets made of stainless steel, plastic, ceramic, titanium, and gold were used. The adherence of S. mutans and C. albicans were studied. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37°C for 48 h, after which the brackets were removed. The cells adhering to the glass were counted and the brackets were studied with SEM.

Results:

When evaluated together, the adherence of S. mutans and C. albicans was increased in the ceramic bracket group. When evaluated separately, metallic brackets had increased number of colony-forming units (CFUs) of S. mutans and the use of titanium brackets increased the CFUs of C. albicans. SEM demonstrated that the adherence of S. mutans and C. albicans together varied according to the bracket materials, with ceramic having the greatest and stainless steel having the least adherence.

Conclusions:

Oral hygiene may be of greater concern with esthetic brackets since this study shows that microbial adhesion is greater with these brackets.

Canadian clinical practice guidelines for invasive candidiasis in adults

Candidemia and invasive candidiasis (C/IC) are life-threatening opportunistic infections that add excess morbidity, mortality and cost to the management of patients with a range of potentially curable underlying conditions. The Association of Medical Microbiology and Infectious Disease Canada developed evidence-based guidelines for the approach to the diagnosis and management of these infections in the ever-increasing population of at-risk adult patients in the health care system. Over the past few years, a new and broader understanding of the epidemiology and pathogenesis of C/IC has emerged and has been coupled with the availability of new antifungal agents and defined strategies for targeting groups at risk including, but not limited to, acute leukemia patients, hematopoietic stem cell transplants and solid organ transplants, and critical care unit patients. Accordingly, these guidelines have focused on patients at risk for C/IC, and on approaches of prevention, early therapy for suspected but unproven infection, and targeted therapy for probable and proven infection.

Genotyping of Candida parapsilosis from three neonatal intensive care units (NICUs) using a panel of five multilocus microsatellite markers: broad genetic diversity and a cluster of related strains in one NICU

Candida parapsilosis (CP) (n = 40) isolated from an unselected patient population in the neonatal intensive care units (NICUs) of three US hospitals were collected over periods of 3.5-9 years. Two previously published microsatellite markers and three additional trinucleotide markers were used to produce multiplex genotypes, which revealed broad strain diversity among the NICU isolates with a combined index of discrimination (D) = 0.997. A cluster of eight related CP strains from four infants in a single NICU was observed. An extended collection of 24 CP isolates from the general population of that hospital showed that the cluster of NICU isolates was related to three isolates from general hospital patients. This microsatellite marker set is suitable to investigate clusters of colonizing and infecting strains of CP.

Patient isolation measures for infants with candida colonization or infection for preventing or reducing transmission of candida in neonatal units

BACKGROUND

Candida is a common nosocomial infection and is associated with increased healthcare costs. In neonates, candida infection is associated with high mortality and morbidity and is transmitted by direct and indirect contact. Patient isolation measures, i.e. single room isolation or cohorting, are usually recommended for infections that spread by contact.

OBJECTIVES

To determine the effect of patient isolation measures (single room isolation and/or cohorting) for infants with candida colonization or infection as an adjunct to routine infection control measures on the transmission of candida to other infants in the neonatal unit.

SEARCH METHODS

Relevant trials in any language were searched in the following databases in July 2011: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2011), MEDLINE, BIOSIS, EMBASE and CINAHL. Proceedings of the Pediatric Academic Societies (from 1987) and ongoing trials were searched.

SELECTION CRITERIA

Types of studies: Cluster randomized trials (where clusters may be defined by hospital, ward, or other subunits of the hospital).

TYPES OF PARTICIPANTS

Neonatal units caring for infants colonized or infected with Candida. Types of interventions: A policy of patient isolation measures (single room isolation or cohorting of infants with Candida colonization or infection) compared to routine isolation measures.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group (CNRG) were used to identify studies and to assess the methodological quality of eligible cluster-randomized trials. Infection rates and colonization rates were to be expressed as rate ratios for each trial and if appropriate for meta-analysis, the generic inverse variance method in RevMan was to be used.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

The review found no evidence to either support or refute the use of patient isolation measures (single room isolation or cohorting) in neonates with candida colonization or infection.Despite the evidence for transmission of candida by contact and evidence of cross-infection by health care workers, no standard policy of patient isolation measures beyond routine infection control measures exists in the neonatal unit. There is an urgent need to research the role of patient isolation measures for preventing transmission of candida in the neonatal unit. Well designed trials randomizing clusters of units or hospitals to a type of patient isolation method intervention are needed.

The effect of cumulative length of hospital stay on the antifungal resistance of Candida strains isolated from critically ill surgical patients

Fluconazole is the first line of therapy for the management of candidiasis. However, fluconazole-resistant strains pose an emerging challenge in everyday clinical practice. In this study, we sought to determine whether cumulative length of hospital stay (CLOS) is a predictive factor for the acquisition of non-susceptible Candida strains to fluconazole. Thirty-three critically ill emergency surgery patients with 56 Candida isolates were enrolled in this prospective study. We divided our isolates according to their minimum inhibitory concentration (MIC) to fluconazole using 8 mcg/ml as a cutoff. We then compared the two groups with respect to basic demographics, antifungal agents prescribed, number of wide-spectrum antibiotics, duration of central venous catheter placement, elapsed time to positive culture, duration of prior hospital stay, and length of hospital stay. Non-susceptible fluconazole samples belonged to patients with a significantly longer prior hospital stay and a longer CLOS (P = 0.02 and 0.01, respectively). The difference between the 2 groups regarding non-albicans strains was statistically significant (P < 0.001). By fitting a non-parametric receiver-operating characteristics (ROC) curve into our analysis, a CLOS ≥ 29 days predicted the occurrence of non-susceptible strains with 90% sensitivity and 79.6% specificity (correct classification 81.5%). A CLOS ≥ 29 days is a strong predictor for the isolation of non-susceptible Candida isolates to fluconazole among critically ill emergency surgery patients. Clinicians should consider the duration of previous hospital stay when deciding on empiric antifungal therapy.

Correlation between Etest, disk diffusion, and microdilution methods for antifungal susceptibility testing of Candida species from infection and colonization

The correlation between the microdilution (MD), Etest (ET), and disk diffusion (DD) methods was determined for amphotericin B, itraconazole and fluconazole. The minimal inhibitory concentration (MIC) of those antifungal agents was established for a total of 70 Candida spp. isolates from colonization and infection. The species distribution was: Candida albicans (n=27), C. tropicalis (n=17), C. glabrata (n=16), C. parapsilosis (n=8), and C. lusitaniae (n=2). Non-Candida albicans Candida species showed higher MICs for the three antifungal agents when compared with C. albicans isolates. The overall concordance (based on the MIC value obtained within two dilutions) between the ET and the MD method was 83% for amphotericin B, 63% for itraconazole, and 64% for fluconazole. Considering the breakpoint, the agreement between the DD and MD methods was 71% for itraconazole and 67% for fluconazole. The DD zone diameters are highly reproducible and correlate well with the MD method, making agar-based methods a viable alternative to MD for susceptibility testing. However, data on agar-based tests for itraconazole and amphotericin B are yet scarce. Thus, further research must still be carried out to ensure the standardization to other antifungal agents.

Candida parapsilosis: a review of its epidemiology, pathogenesis, clinical aspects, typing and antimicrobial susceptibility

The Candida parapsilosis family has emerged as a major opportunistic and nosocomial pathogen. It causes multifaceted pathology in immuno-compromised and normal hosts, notably low birth weight neonates. Its emergence may relate to an ability to colonize the skin, proliferate in glucose-containing solutions, and adhere to plastic. When clusters appear, determination of genetic relatedness among strains and identification of a common source are important. Its virulence appears associated with a capacity to produce biofilm and production of phospholipase and aspartyl protease. Further investigations of the host-pathogen interactions are needed. This review summarizes basic science, clinical and experimental information about C. parapsilosis.

The effects of orthodontic appliances on Candida in the human mouth

BACKGROUND

Candida is an opportunistic pathogen present in about 50-60% of the healthy human population, and becomes pathogenic when the host immune defence is undermined such as in HIV infection. Adhesion and colonization of the oral cavity by Candida albicans is an initial step in candidosis, and the presence of orthodontic and other oral appliances seems to alter the oral ecological environment, hence may tip the balance to favour the candidal presence.

OBJECTIVE

The purpose of this paper was to review the literature with specific attention to prevalence; intra-oral density of the candidal organisms; and Candida carriage status in orthodontic patients before, during, and after treatment.

CONCLUSIONS

The limited amount of literature demonstrated that the density of Candida increases; the most common Candida species isolated in the orthodontic patients was C. albicans; and that there seems to be a direct relationship between the presence of a removable appliance, Candida, and low salivary pH levels. No healthy patients developed Candida infection from the orthodontic appliances. However, there seems to be a trend that some non-Candida carriers converted to Candida carriers following the insertion of the appliances by unknown mechanism. This may indicate a more cautious approach when providing orthodontic treatments to immunocompromised children concerning the possible increased risk of candidal infection.

A model of exposure to rotavirus from nondietary ingestion iterated by simulated intermittent contacts

Existing microbial risk assessment models rarely incorporate detailed descriptions of human interaction with fomites. We develop a stochastic-mechanistic model of exposure to rotavirus from nondietary ingestion iterated by simulated intermittent fomes-mouth, hand-mouth, and hand-fomes contacts typical of a child under six years of age. This exposure is subsequently translated to risk using a simple static dose-response relationship. Through laboratory experiments, we quantified the mean rate of inactivation for MS2 phage on glass (0.0052/hr) and mean transfer between fingertips and glass (36%). Simulations using these parameters demonstrated that a child's ingested dose from a rotavirus-contaminated ball ranges from 2 to 1,000 virus over a period of one hour, with a median value of 42 virus. These results were heavily influenced by selected values of model parameters, most notably the concentration of rotavirus on fomes, frequency of fomes-mouth contacts, frequency of hand-mouth contacts, and virus transferred from fomes to mouth. The model demonstrated that mouthing of fomes is the primary exposure route, with hand mouthing contributions accounting for less than one-fifth of the child's dose over the first 10 minutes of interaction.

Patient isolation measures for infants with candida colonization or infection for preventing or reducing transmission of candida in neonatal units

BACKGROUND

Candida is one of the most common nosocomial infections in the intensive care setting worldwide and is associated with increased healthcare costs. In neonates, candida infection is associated with high mortality and morbidity. Candida is transmitted by direct and indirect contact. Routine infection control measures that include standard precautions are routinely employed to prevent spread of nosocomial infections. Patient isolation measures, i.e. single room isolation or cohorting, are usually recommended for infections spread by contact.

OBJECTIVES

To determine the effect of patient isolation measures (single room isolation and/or cohorting) for infants with candida colonization or infection as an adjunct to routine infection control measures on the transmission of candida to other infants in the neonatal unit.

SEARCH STRATEGY

Relevant trials in any language were searched in the following databases in Jan 2007: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2006), MEDLINE (1966 - Jan 2007) and PREMEDLINE, EMBASE (1980 - Jan 2007), CINAHL (1982 - Jan 2007). Proceedings of the Pediatric Academic Societies (American Pediatric Society, Society for Pediatric Research) and the European Society for Pediatric Research (1987 - Jan 2007) were also searched in Jan 2007. Authors or other experts were contacted for more information on relevant published or unpublished trials. Additional searches were also made in the reference lists of relevant journal articles and in the reviewer's personal files.

SELECTION CRITERIA

Types of studies: Cluster randomized trials (where clusters may be defined by hospital, ward, or other subunits of the hospital).

TYPES OF PARTICIPANTS

Neonatal units caring for infants colonized or infected with candida. Types of interventions: A policy of patient isolation measures (single room isolation or cohorting of infants with candida colonization or infection) compared to routine isolation measures.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group (CNRG) were to be used to identify studies and to assess the methodological quality of eligible trials. The statistical package (RevMan 4.2) provided by the Cochrane Collaboration was to be used. In cluster-randomized trials, if the unit of analysis of the trial was the cluster (not individuals) and analysis took into account the correlation between clusters, the inverse variance method was to be used for meta-analysis. If this was not the case, a narrative synthesis was to be made without meta-analysis. Infection rates and colonization rates were to be expressed as rate ratios for each trial and if appropriate for meta-analysis, the generic inverse variance method in RevMan was to be used.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

The review found no evidence to either support or refute the use of patient isolation measures (single room isolation or cohorting) in neonates with candida colonization or infection. Despite the evidence for transmission of candida by direct or indirect contact and evidence of cross-infection by health care workers, no standard policy of patient isolation measures beyond routine infection control measures exists in the neonatal unit. There is an urgent need to research the role of patient isolation measures for preventing transmission of candida in the neonatal unit. Cluster randomized trials involving multiple units or hospitals with randomized allocation of one type of patient isolation measure or the other (i.e. single room isolation or cohorting) with careful consideration for determining an appropriate sample size and analysis would be the most appropriate method to research this intervention.

Influence of Different Orthodontic Brackets on Adherence of Microorganisms In Vitro

OBJECTIVE

To define the capacity of different bracket materials to modify the growth and adherence of microorganisms.

METHODS

Three types of brackets from the right upper central incisor were used: metallic, ceramic, and composite. Streptococcus mutans and Candida albicans were studied. The association of both species was also evaluated. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37 degrees C for 48 hours, after which the brackets were removed. The supernatant was removed from the flasks, the cells adhering to the glass were counted, and the brackets were studied with electron microscopy.

RESULTS

The adherence of Streptococcus mutans was not modified by the different brackets. The adherence of Candida albicans was increased by the composite bracket, whereas the use of metallic brackets decreased the number of colony-forming units (CFUs). By electron microscopy we demonstrated that the adherence of Streptococcus mutans plus Candida albicans together varied according to the bracket materials with composite > ceramic > metallic.

CONCLUSIONS

Orthodontic appliances serve as different impact zones and modify microbial adherence and colonization, acting as foreign reserves and possible sources of infection.

How long do nosocomial pathogens persist on inanimate surfaces? A systematic review

BACKGROUND

Inanimate surfaces have often been described as the source for outbreaks of nosocomial infections. The aim of this review is to summarize data on the persistence of different nosocomial pathogens on inanimate surfaces.

METHODS

The literature was systematically reviewed in MedLine without language restrictions. In addition, cited articles in a report were assessed and standard textbooks on the topic were reviewed. All reports with experimental evidence on the duration of persistence of a nosocomial pathogen on any type of surface were included.

RESULTS

Most gram-positive bacteria, such as Enterococcus spp. (including VRE), Staphylococcus aureus (including MRSA), or Streptococcus pyogenes, survive for months on dry surfaces. Many gram-negative species, such as Acinetobacter spp., Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Serratia marcescens, or Shigella spp., can also survive for months. A few others, such as Bordetella pertussis, Haemophilus influenzae, Proteus vulgaris, or Vibrio cholerae, however, persist only for days. Mycobacteria, including Mycobacterium tuberculosis, and spore-forming bacteria, including Clostridium difficile, can also survive for months on surfaces. Candida albicans as the most important nosocomial fungal pathogen can survive up to 4 months on surfaces. Persistence of other yeasts, such as Torulopsis glabrata, was described to be similar (5 months) or shorter (Candida parapsilosis, 14 days). Most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhino virus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, HAV, polio- or rota virus, persist for approximately 2 months. Blood-borne viruses, such as HBV or HIV, can persist for more than one week. Herpes viruses, such as CMV or HSV type 1 and 2, have been shown to persist from only a few hours up to 7 days.

CONCLUSION

The most common nosocomial pathogens may well survive or persist on surfaces for months and can thereby be a continuous source of transmission if no regular preventive surface disinfection is performed.

Disinfection of fabrics and carpets artificially contaminated with calicivirus: relevance in institutional and healthcare centres

Fabrics and carpets are used widely as surface coverings or linens in healthcare settings and are prone to contamination with infectious agents such as noroviruses (NoVs). Laundering, water cleaning and vacuuming are considered to be adequate for routine cleaning of these materials, but no standard procedure for their disinfection is available in case of contamination. Testing disinfectants for their efficacy against NoVs is difficult because these viruses cannot be cultivated in vitro. Therefore, feline calicivirus (FCV) has gained acceptance as a surrogate model for NoVs in disinfectant efficacy testing. The present study evaluated five disinfectants against FCV on various fabrics or carpets. FCV was dried on fabrics and carpets, followed by treatment with a given disinfectant for a defined contact time of 1, 5 or 10 min. The surviving virus was then eluted and titrated in Crandell-Reese feline kidney cells to determine virus inactivation. A disinfectant was considered to be effective if it inactivated at least 99% of the applied virus. Metricide, an activated dialdehyde-based product, was found to be the most effective disinfectant on all types of fabric and carpet, inactivating more than 99.99% of the virus in 1-10 min. In general, effectiveness of disinfectants increased with an increase in exposure time from 1 to 10 min. The disinfection of carpets was more difficult than the disinfection of fabrics; 100% polyester was the least amenable to disinfection. Only Metricide and Microbac-II (a phenolic compound) were able to inactivate 99% of FCV on 100% polyester. In summary, activated dialdehyde was found to be uniformly active against FCV on all types of material tested.

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.

Epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs

The etiology of nosocomial infections, the frequency of contaminated hands with the different nosocomial pathogens, and the role of health care workers' hands during outbreaks suggest that a hand hygiene preparation should at least have activity against bacteria, yeasts, and coated viruses. The importance of efficacy in choosing the right hand hygiene product is reflected in the new Centers for Disease Control and Prevention guideline on hand hygiene (J. M. Boyce and D. Pittet, Morb. Mortal. Wkly. Rep. 51:1-45, 2002). The best antimicrobial efficacy can be achieved with ethanol (60 to 85%), isopropanol (60 to 80%), and n-propanol (60 to 80%). The activity is broad and immediate. Ethanol at high concentrations (e.g., 95%) is the most effective treatment against naked viruses, whereas n-propanol seems to be more effective against the resident bacterial flora. The combination of alcohols may have a synergistic effect. The antimicrobial efficacy of chlorhexidine (2 to 4%) and triclosan (1 to 2%) is both lower and slower. Additionally, both agents have a risk of bacterial resistance, which is higher for chlorhexidine than triclosan. Their activity is often supported by the mechanical removal of pathogens during hand washing. Taking the antimicrobial efficacy and the mechanical removal together, they are still less effective than the alcohols. Plain soap and water has the lowest efficacy of all. In the new Centers for Disease Control and Prevention guideline, promotion of alcohol-based hand rubs containing various emollients instead of irritating soaps and detergents is one strategy to reduce skin damage, dryness, and irritation. Irritant contact dermatitis is highest with preparations containing 4% chlorhexidine gluconate, less frequent with nonantimicrobial soaps and preparations containing lower concentrations of chlorhexidine gluconate, and lowest with well-formulated alcohol-based hand rubs containing emollients and other skin conditioners. Too few published data from comparative trials are available to reliably rank triclosan. Personnel should be reminded that it is neither necessary nor recommended to routinely wash hands after each application of an alcohol-based hand rub. Long-lasting improvement of compliance with hand hygiene protocols can be successful if an effective and accessible alcohol-based hand rub with a proven dermal tolerance and an excellent user acceptability is supplied, accompanied by education of health care workers and promotion of the use of the product.

Morphotypic and genotypic characterization of sequential Candida parapsilosis isolates from an outbreak in a pediatric intensive care unit

Candidemia outbreaks that due to cross-infection are an emerging problem in hospitals. Typing of microorganisms is an essential tool for understanding the epidemiologic aspects of the infection. Techniques based on phenotypic characteristics are inexpensive and easy to perform but are limited by their lack of reproducibility. This study assessed the value of several phenotypic and genotypic techniques that are used in epidemiologic investigations of Candida parapsilosis in clinical practice and used a combination of these methods to analyze outbreak of C. parapsilosis candidemia. Random amplification of polymorphic DNA polymerase chain reaction with several primers was unsatisfactory because it lacked discriminatory power. By simplifying the reading of the morphotypes, we increased their reproducibility for each malt agar and 2,3,5-triphenyltetrazolium media (97% and 90%) and thus their suitability for its use. The combination of electrophoretic karyotype and the simplified morphotypes was rapid and practical to characterize the different clusters involved in the intensive care unit outbreak.

Testing chemical germicides against Candida species using quantitative carrier and fingerpad methods

Six disinfectants were tested against Candida albicans, C. parapsilosis and C. tropicalis using quantitative carrier tests based on glass (QCT-1) and metal (QCT-2) surfaces. C. albicans was also used to test four topical agents by a fingerpad method. Hard water (200 ppm as CaCO(3)) was the product diluent. In preliminary tests with QCT-1 and QCT-2, the testing was with or without a soil load; subsequent tests and fingerpad tests included soil. In QCT-1 and QCT-2, each carrier received 10 microL (5.0 x 10(6) - 1.0 x 10(7)colony forming units) of Candida, and was air dried for 1 h, then exposed to 1 mL or 50 microL of test product at 22 +/- 2 degrees C for up to 10 min. Controls received an equivalent volume of saline. For fingerpad tests, each digit received 10 microL of inoculum, which was allowed to dry and exposed to 1 mL of test product for 20 s. Inoculated plates of Sabouraud's dextrose agar were held for 48 h at 30 degrees C and colonies counted to determine reductions in colony forming units. In tests on both hard surfaces and fingerpads, ethanol and products based on ethanol reliably and rapidly inactivated all the Candida species tested. Products with sufficient potency to have tuberculocidal claims produced substantial reductions in the titre of C. albicans, although some showed a lesser reduction in titre of C. tropicalis and C. parapsilosis. This may reflect differences in cell hydrophobicity between Candida species, and highlights the need for care in selecting a suitable surrogate for disinfectant tests. The quantitative carrier and fingerpad protocols are suitable for assessing the activity of disinfectants and topical antiseptics against candida.