Candida albicans endocarditis associated with a contaminated aortic valve allograft: implications for regulation of allograft processing

Ten-year experience with cryopreserved vascular allografts in the Croatian Cardiovascular Tissue Bank

The Croatian Cardiovascular Tissue Bank (CTB) was established in June 2011. Activities managed by CTB are processing of heart valves and blood vessels, as well as quality control, storage, medical release and distribution of allografts. The aim of this report is to present CTB's vascular tissue activities and retrospectively evaluate the outcomes of their use in the University Hospital Centre Zagreb. Between June 2011 and July 2021, 90 vascular allografts (VAs) from 55 donors after brain death were referred to CTB. Only 54% of VAs met the tissue quality requirements while 46% of tissues were discarded. The most frequent reasons for discard were unacceptable morphology and initial microbiological contamination. Altogether 42 VAs were released for transplantation and 37 of them were used in 27 surgical procedures. The most common indication for surgery was prosthetic graft or stent infection. According to the anatomic position of vascular reconstruction, patients were divided in the aortic and peripheral reconstruction group. A total of 23 patients were treated. In the aortic reconstruction group 58% of patients did not experience any graft-related complications. In the group of patients who underwent peripheral reconstruction significant incidence of reinfection was observed highlighting it as a major graft-related complication. Despite the small patient groups and limited duration of follow-up, presented clinical outcomes provide valuable information on the efficacy of vascular allografts. Additional clinical results collected on a larger patient groups and comparison to other reconstructive treatment options are necessary.

Intramedullary Foreign Bodies within Fresh-Frozen Fibular Cortical Allograft: A Case Report

CASE

A 71-year-old man with a proximal humerus fracture nonunion underwent surgery augmented by a fibular cortical strut allograft. On placing the allograft within the proximal humerus, fluoroscopic images showed 2 foreign bodies found to be broken drill bits located within the allograft. The drill bits were extracted, and the allograft was reprepared for use.

CONCLUSION

After 2 years of follow-up, no significant sequela related to the foreign bodies was noted. To the best of our knowledge, this case report represents the first-of-its-kind occurrence of broken drill bits found within bone allograft.

Microbiological assessment of arterial allografts processed in a tissue bank

The transmission of microbial infection through tissue allografts is one of the main risks that must be controlled in tissue banks. Therefore, microbiological monitoring controls and validated protocols for the decontamination of tissues during processing have been implemented. This study is based on the evaluation of data from microbiological cultures of arteries (mainly long peripheral arteries) processed in the tissue bank of Valencia (Spain). Donors' profile, pre- and post-disinfection tissue samples were assessed. The presence of residual antibiotics in disinfected tissues was determined and the antimicrobial potential of these tissues was tested. Our overall contamination rate was 23.69%, with a disinfection rate (after antibiotic incubation) of 87.5%. Most (76.09%) of the microbial contaminants were identified as Gram positive. Arterial allografts collected from body sites affected by prior organ removal showed higher risk of contamination. Only vancomycin was detected as tissue release. The antimicrobial effect on Candida albicans was lower than that for bacterial species. Risk assessment for microbial contamination suggested the donor's skin and the environment during tissue collection as the main sources for allograft contamination. Antibiotic-disinfected arterial allografts showed antimicrobial potential.

Does microbiological contamination of homografts prior to decontamination affect the outcome after right ventricular outflow tract reconstruction?

 

OBJECTIVES

Homografts are often in short supply. Today, European guidelines recommend that all tissues contaminated by any of 18 different bacteria and fungi be discarded before antibiotic decontamination has been conducted. The tissue bank in Lund uses more liberal protocols: It accepts all microbes prior to decontamination except multiresistant microbes and Pseudomonas species. The aim of this study was to analyse the effect of contamination on the long-term outcome and occurrence of endocarditis in recipients.

METHODS

Data were collected on homografts and on recipients of homografts in the right ventricular (RV) outflow tract who were operated on between 1995 and 2018 in Lund. The long-term outcome of recipients was analysed in relation to different types of contamination using Cox proportional hazard regression. The proportion of patients with endocarditis was analysed with the χ2 test.

RESULTS

The study included 509 implanted homografts. Follow-up was a maximum of 24 years and 99% complete. A total of 156 (31%) homografts were contaminated prior to antibiotic decontamination. Homografts contaminated with low-risk microbes had the lowest reintervention rate, but there was no significant difference compared to no contamination [hazard ratio (HR) 1.1, 95% confidence interval (CI) 0.73-1.7] or contamination with high-risk microbes (HR 1.6, 95% CI 0.87-2.8) in the multivariable analysis. There was no significant difference in the proportion of cases of endocarditis during the follow-up period between recipients of homografts contaminated prior to decontamination and recipients of homografts with no contamination (P = 0.83).

CONCLUSIONS

Contamination of homograft tissue prior to decontamination did not show any significant effect on the long-term outcome or the occurrence of endocarditis after implantation in the RV outflow tract. Most contaminated homografts can be used safely after approved decontamination.

Validation of Microbiological Testing of Tissue Preparations with Different Incubation Temperatures

Introduction

The European Pharmacopoeia (Ph. Eur.) provides principles for microbiological testing of tissue preparations. According to the Ph. Eur., tests should be performed at different temperatures for detection of aerobic bacteria and fungi (20–25°C) vs. anaerobic bacteria (30–35°C). Semiautomated systems using blood culture bottles are already widely used and they are adequate for growth detection. Resin-containing bottles and the addition of penicillinase permit testing of culture media containing antibiotics.

Materials and Methods

At 3 temperatures (21, 30, and 35°C) cornea culture media with and without dextran (CM II and CM I) and thermal disinfected femoral head medium (FH) were spiked with the 6 reference strains recommended by the Ph. Eur. (additionally: Enterococcus faecalis, Staphylococcus epidermidis, and Cutibacterium acnes). Microbial growth was monitored with the BACTEC^TM FX unit or visually at 21°C.

Results

Growth for all strains was detected with each medium at all 3 temperatures, except for C. acnes at 21°C (all media) and 30°C with FH. C. acnes had the highest times to detection, requiring test durations of 14 days. Microbial growth was faster at 30 and 35°C compared to 21°C.

Conclusion

The requirements according to the Ph. Eur. for a successful method suitability test could be fulfilled for the semiautomated blood culture bottle system with the BACTEC^TM FX unit for the media and microorganisms used. In the presented validation study 35°C was shown to be the incubation temperature with the fastest growth, of the majority of the test strains used, and complete detection within 14 days.

Experimental procedures for decontamination and microbiological testing in cardiovascular tissue banks

IMPACT STATEMENT

Sterility testing is a critical issue in the recovery, processing, and release of tissue allografts. Contaminated allografts are often discarded, increasing costs, and reducing tissue stocks. Given these concerns, it is important to determine the most effective methodology for sterility testing. This work provides an overview of microbiological methods for sampling and culturing donor grafts for cardiovascular tissue banking.

Candida endocarditis: systematic literature review from 1997 to 2014 and analysis of 29 cases from the Italian Study of Endocarditis

INTRODUCTION

Candida Endocarditis (CE) is a deadly disease. It is of paramount importance to assess risk factors for acquisition of both Candida native (NVE) and prosthetic (PVE) valve endocarditis and relate clinical features and treatment strategies with the outcome of the disease. Areas covered: We searched the literature using the Pubmed database. Cases of CE from the Italian Study on Endocarditis (SEI) were also included. Overall, 140 cases of CE were analyzed. Patients with a history of abdominal surgery and antibiotic exposure had higher probability of developing NVE than PVE. In the PVE group, time to onset of CE was significantly lower for biological prosthesis compared to mechanical prosthesis. In the whole population, greater age and longer time to diagnosis were associated with increased likelihood of death. Patients with effective anti-biofilm treatment, patients who underwent cardiac surgery and patients who were administered chronic suppressive antifungal treatment showed increased survival. For PVE, moderate active anti-biofilm and highly active anti-biofilm treatment were associated with lower mortality. Expert commentary: Both NVE and PVE could be considered biofilm-related diseases, pathogenetically characterized by Candida intestinal translocation and initial transient candidemia. Cardiac surgery, EAB treatment and chronic suppressive therapy might be crucial in increasing patient survival.

Disinfection of human cardiac valve allografts in tissue banking: systematic review report

Cardiovascular allografts are usually disinfected using antibiotics, but protocols vary significantly between tissue banks. It is likely that different disinfection protocols will not have the same level of efficacy; they may also have varying effects on the structural integrity of the tissue, which could lead to significant differences in terms of clinical outcome in recipients. Ideally, a disinfection protocol should achieve the greatest bioburden reduction with the lowest possible impact on tissue integrity. We conducted a systematic review of methods applied to disinfect cardiovascular tissues. The use of multiple broad spectrum antibiotics in conjunction with an antifungal agent resulted in the greatest reduction in bioburden. Antibiotic incubation periods were limited to less than 24 h, and most protocols incubated tissues at 4 °C, however one study demonstrated a greater reduction of microbial load at 37 °C. None of the reviewed studies looked at the impact of these disinfection protocols on the risk of infection or any other clinical outcome in recipients.

Management of early graft infections in the ascending aorta and aortic arch: a comparison between graft replacement and graft preservation techniques

OBJECTIVES

Treatment of infected thoracic aortic grafts is associated with considerable morbidity and mortality. The replacement of an infected graft is an effective strategy, yet a complex surgical endeavour, especially if the aortic root or aortic arch is involved. In situ graft-sparing surgical therapy with continuous mediastinal irrigation after surgical debridement might offer an alternative in the management of early graft infections in the thoracic aorta.

METHODS

Between 1996 and August 2015, 25 patients were treated in our institution for early graft infection after thoracic aortic surgery via sternotomy. In 11 patients, the infected prosthesis was replaced by a cryopreserved homograft or a biological valved pericardial xenograft. In 14 patients, an attempt to salvage the graft was made by resternotomy, aggressive debridement and subsequent continuous mediastinal antibiotic irrigation over a course of 2 weeks, accompanied by systemic antibiotic therapy.

RESULTS

In-hospital mortality was comparable (replacement group: 2/11 = 18%, graft-sparing group: 2/14 = 14%, P = ns). The time interval from the initial surgery was significantly shorter in the graft-sparing group (replacement group: 165 days [range 95-300 days] and graft-sparing group: 24 days [range 15-93 days], P = 0.004]. Two patients (14%), who were treated with the graft-sparing approach >100 days after the initial surgery, were retreated for infection, and 1 due to an intra-aortic infection of an aortic arch hybrid stent graft was not amenable to external irrigation (median follow-up: 1.5 years [range 1.1-2.1 years]). One patient in the replacement group (9%) was reoperated on due to homograft degeneration (median follow-up: 6.0 years [3.0-8.9 years]).

CONCLUSIONS

In situ graft-sparing surgical therapy is safe and effective if diagnosis and treatment of aortic graft infection is initiated promptly and aggressively (ideally <1 month post-surgery). Our method produces good midterm results (3 years). For aortic graft infections that become clinically apparent >3-6 months after surgery, replacement of grafts with biological conduits (homografts or pericardial xenografts) most likely remains the best treatment option.

Residual antibiotics in decontaminated human cardiovascular tissues intended for transplantation and risk of falsely negative microbiological analyses

We investigated the presence of antibiotics in cryopreserved cardiovascular tissues and cryopreservation media, after tissue decontamination with antibiotic cocktails, and the impact of antibiotic residues on standard tissue bank microbiological analyses. Sixteen cardiovascular tissues were decontaminated with bank-prepared cocktails and cryopreserved by two different tissue banks according to their standard operating procedures. Before and after decontamination, samples underwent microbiological analysis by standard tissue bank methods. Cryopreserved samples were tested again with and without the removal of antibiotic residues using a RESEP tube, after thawing. Presence of antibiotics in tissue homogenates and processing liquids was determined by a modified agar diffusion test. All cryopreserved tissue homogenates and cryopreservation media induced important inhibition zones on both Staphylococcus aureus- and Pseudomonas aeruginosa-seeded plates, immediately after thawing and at the end of the sterility test. The RESEP tube treatment markedly reduced or totally eliminated the antimicrobial activity of tested tissues and media. Based on standard tissue bank analysis, 50% of tissues were found positive for bacteria and/or fungi, before decontamination and 2 out of 16 tested samples (13%) still contained microorganisms after decontamination. After thawing, none of the 16 cryopreserved samples resulted positive with direct inoculum method. When the same samples were tested after removal of antibiotic residues, 8 out of 16 (50%) were contaminated. Antibiotic residues present in tissue allografts and processing liquids after decontamination may mask microbial contamination during microbiological analysis performed with standard tissue bank methods, thus resulting in false negatives.

The use of allograft in joint-preserving surgery for ankle osteochondral lesions and osteoarthritis

The surgical management of young patients with large osteochondral lesions of the talus or end-stage osteoarthritis of the ankle joint presents a challenge to the orthopedic surgeon because these are well-recognized sources of pain and dysfunction. Procedures designed to address these disorders either have a limited role because of poor success rates or have significant implications, such as with the total ankle arthroplasty. Fresh osteochondral allografts allow defective tissue to be anatomically matched and reconstructed through transplantation. This article presents an overview of fresh osteochondral allografts, as well as potential concerns with their use, and summarizes the current literature.

Health care-associated infection outbreak investigations by the Centers for Disease Control and Prevention, 1946-2005

Since 1946, Centers for Disease Control and Prevention (CDC) personnel have investigated outbreaks of infections and adverse events associated with delivery of health care. CDC Epidemic Intelligence Service officers have led onsite investigations of these outbreaks by systematically applying epidemiology, statistics, and laboratory science. During 1946-2005, CDC Epidemic Intelligence Service officers conducted 531 outbreak investigations in facilities across the United States and abroad. Initially, the majority of outbreaks involved gastrointestinal tract infections; however, in later years, bloodstream, respiratory tract, and surgical wound infections predominated. Among pathogens implicated in CDC outbreak investigations, Staphylococcus aureus, Enterococcus species, Enterobacteriaceae, nonfermentative Gram-negative bacteria, or yeasts predominated, but unusual organisms (e.g., the atypical mycobacteria) were often included. Outbreak types varied and often were linked to transfer of colonized patients or health care personnel between facilities (multihospital outbreaks), national distribution of contaminated products, use of invasive medical devices, or variances in practices and procedures in health care environments (e.g., intensive care units, water reservoirs, or hemodialysis units). Through partnerships with health care facilities and local and state health departments, outbreaks were terminated and lives saved. Data from investigations invariably contributed to CDC-generated guidelines for prevention and control of health care-associated infections.

Heart valve allograft decontamination with antibiotics: impact of the temperature of incubation on efficacy

Heart valve allografts are typically processed at 4°C in North America, including the step of antibiotic decontamination. In our own experience with heart valve banking, we often observe persistent positive cultures following decontamination at wet ice temperature. We hypothesized that warmer temperatures of incubation might increase the efficacy of the decontamination procedure. In a first series of experiments, 12 different bacterial species were grown overnight, frozen in standardized aliquots and used directly to inoculate antibiotic cocktail aliquots at 10⁵ colony-forming units (CFU)/ml. The antibiotic cocktail contains vancomycin (50 μg/ml), gentamicin (80 μg/ml) and cefoxitin (240 μg/ml) in Dulbecco's Modified Eagle's Medium. Inoculated aliquots were incubated at 4, 22 and 37°C and CFUs were determined at regular intervals up to 24 h post-inoculation. In a second set of experiments, 10 heart valves were spiked with 5000 CFU/ml and incubated with antibiotics at 4 and 37°C for 24 h. The final rinse solutions of these heart valves were filtered and tested for bacterial growth. After 24 h of incubation, CFUs of all 12 bacterial species were reduced by a factor of only one to two logs at 4°C whereas log reductions of 3.7 and 5.0 or higher were obtained at 22 and 37°C, respectively. Most microorganisms, including Staphylococcus epidermidis, Lactococcus lactis lactis and Propionibacterium acnes survived well the 24-h antibiotic treatment at 4°C (< 1 Log reduction). All 10 heart valves that were spiked with microorganisms had positive final rinse solutions after antibiotic soaking at 4°C, whereas 8 out of 10 cultures were negative when antibiotic decontamination was done at 37°C. These experiments show that a wet ice temperature greatly reduces the efficacy of the allograft decontamination process as microorganisms survived well to a 24-h 4°C antibiotic treatment. This could explain the high rate of positive post-processing cultures obtained with our routine tissue decontamination procedure. Increasing the decontamination temperature from 4 to 37°C may significantly reduce the incidence of post-disinfection bacterial contamination of heart valves.

Organ and tissue safety workshop 2007: advances and challenges

A workshop in June 2005 ("Preventing Organ and Tissue Allograft-Transmitted Infection: Priorities for Public Health Intervention") identified gaps in organ and tissue safety in the US. Participants developed a series of allograft safety initiatives. "The Organ and Tissue Safety Workshop 2007: Advances and Challenges" assessed progress and identified priorities for future interventions. Awareness of the challenges of allograft-associated disease transmission has increased. The Transplantation Transmission Sentinel Network will enhance communication surrounding allograft-associated disease transmission. Other patient safety initiatives have focused on adverse event reporting and microbiologic screening technologies. Despite progress, improved recognition and prevention of donor-derived transmission events is needed. This requires systems integration across the organ and tissue transplantation communities including organ procurement organizations, eye and tissue banks, and transplant infectious disease experts. Commitment of resources and improved coordination of efforts are required to develop essential tools to enhance safety for allograft recipients.

Musculoskeletal allograft risks and recalls in the United States

There have been several improvements to the US tissue banking industry over the past decade. Tissue banks had limited active government regulation until 1993, at which time the US Food and Drug Administration began regulatory oversight because of reports of disease transmission from allograft tissues. Reports in recent years of disease transmission associated with the use of allografts have further raised concerns about the safety of such implants. A retrospective review of allograft recall data was performed to analyze allograft recall by tissue type, reason, and year during the period from January 1994 to June 30, 2007. During the study period, more than 96.5% of all allograft tissues recalled were musculoskeletal. The reasons underlying recent musculoskeletal tissue recalls include insufficient or improper donor evaluation, contamination, recipient infection, and positive serologic tests. Infectious disease transmission following allograft implantation may occur if potential donors are not adequately evaluated or screened serologically during the prerecovery phase and if the implant is not sterilized before implantation.

Infections and human tissue transplants: review of FDA MedWatch reports 2001-2004

BACKGROUND

More than 1.5 million tissue allografts are transplanted annually in the U.S. As part of the federal effort to improve tissue safety, FDA's May 2005 Current Good Tissue Practices (CGTP) Rule requires tissue establishments to report to FDA serious infectious adverse events following allograft transplantation. To provide baseline data, we summarize reports of such infections received by FDA prior to the CGTP Rule.

METHODS

We reviewed reports received by FDA's MedWatch adverse event reporting system during 2001-2004. Our case definition was a reported infection in a human tissue transplant recipient within 1 year of transplantation. We examined demographics, tissue type, clinical outcomes and interventions, infectious organism(s), time from transplant to infection and reporter characteristics.

RESULTS

We identified 83 reports of infections following allograft transplantations. Median patient age was 40 years (range: 1 month-87 years). The allografts included heart valves (42%), tendons (33%), bones (8%), blood vessels (6%), ocular tissues (5%), and skin (4%). Commonly reported outcomes and interventions were hospitalization (72%), antibiotic therapy (46%) and graft removal (42%). Nine of 11 patients who expired had received heart valves. In 65 reports that identified suspected organisms, bacteria were most common (42), followed by fungi (25) and prions (1). The median time from transplant to infection was 5.5 weeks (range: 3 days-52 weeks). Tissue manufacturers submitted 26% of reports. Among the remaining 74%, the reporters were quality assurance staff, infection control or risk management personnel (45%); physicians (15%); consumers (15%); nurses (13%); and surgical staff (12%).

CONCLUSION

This is the first review of reports to FDA for infections following allograft tissue transplantations. Infections led to serious outcomes and involved many tissue types. Although we were unable to confirm that reported infections were caused by the suspected tissue product, required reporting by tissue establishments and improvements in adverse event investigation will help to improve tissue safety surveillance.

Human tissue oversight in hospitals: an AABB survey

BACKGROUND

Reports of human tissue allograft-transmitted infections have underscored the need for better accounting of allografts in health-care facilities. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) implemented new storage and issuance tissue standards for hospital oversight as of July 1, 2005. This study sought to survey hospital tissue responsibilities.

STUDY DESIGN AND METHODS

The AABB Tissue Task Force conducted a Web-based survey distributed to all 904 hospital institutional members in January 2005. The survey asked about tissue type used, breadth of responsibility, hospital department involvement, and views on AABB involvement. Data from 402 of 904 (45%) respondents were tabulated and analyzed.

RESULTS

Among the 402 respondents, 325 (81%) used allogeneic and/or autologous human tissue. The most frequently used tissues were musculoskeletal (n = 240, 74%) and skin (n = 169, 52%) allografts. The department of surgery (e.g., operating room; n = 245, 76%) most often had responsibility for tissue use, followed by the blood bank (i.e., transfusion service; n = 164, 51%); surgery most frequently had responsibility for all tissue types except peripheral blood progenitor cells. Only 32 of 402 (8%) respondents had plans for increased oversight in the next 12 months; 129 of 178 (72%) thought there was a role for AABB in developing guidance on hospital tissue responsibilities.

CONCLUSIONS

In this survey, most AABB member hospital respondents indicated facility use of allogeneic and/or autologous tissues. Although tissue allograft responsibility by surgery was extensive, hospital blood banks also had significant involvement. Few blood banks, however, plan increased oversight in the near future. Given JCAHO standards, blood banks have an opportunity to assist their hospital in planning for assigned tissue responsibilities and oversight to ensure patient safety.

Bacterial infection transmitted by human tissue allograft transplantation

Bacterial contamination of tissue allografts obtained from cadaveric donors has been a serious cause of morbidity and mortality in recipients. Recent cases of fatal and nonfatal bacterial infections in recipients of contaminated articular cartilage (distal femur) and tendon allografts have called attention to the importance of avoiding tissue donors suspected of carrying infectious disease, of not processing donated tissue carrying virulent bacteria, the occurrence of falsely negative final sterility tests, and the need to sterilize tissues. These cases demonstrated that contamination can arise from an infected donor, during tissue removal from cadaveric donors, from the processing environment, and from contaminated supplies and reagents used during processing. Final sterility testing can be unreliable, especially when antibiotics remain on tissues. There is an increasing need for control of microbial contamination in tissue banks, and sterilization of tissue allografts should be recommended whenever possible.

Decreasing latitude and increasing regulation in transplantable tissue programs

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ADVANCED TECHNOLOGY and improved surgical techniques have led to new therapeutic uses for allografts.

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DISEASE TRANSMISSION via allograft tissue transplants has prompted federal intervention in the tissue banking industry and resulted in federal regulations.

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NEW STANDARDS from the Joint Commission on Accreditation of Healthcare Organizations became effective July 1,2005, and apply to all hospitals that store or implant allograft tissues. These standards include mandatory policies on all aspects of hospital transplantation programs, including tissue ordering, receipt, storage, issuance, and record keeping. AORN J 82 (November 2005) 806–814.

A meta-analysis of medical versus surgical therapy for Candida endocarditis

OBJECTIVES

The optimal management of Candida infective endocarditis (IE) is unknown.

METHODS

We reviewed all 879 cases of Candida IE reported from 1966-2002 in the peer-reviewed literature to better understand the role of medical and surgical therapies. This review included 163 patients from 105 reports that met our inclusion criteria: 31 cases treated with antifungal monotherapy, 25 cases treated with medical antifungal combination therapy, and 107 cases treated with adjunctive surgical plus medical antifungal therapy. We also used meta-analytic techniques to evaluate 22 observational case-series (72 patients) of the 105 reports with two or more patients with definite Candida IE.

RESULTS

We found that in patients who underwent adjunctive surgery there was a lower reported proportion of deaths [prevalence odds ratio (POR)=0.56; 95% confidence interval (CI)=0.16, 1.99)]. Higher mortality was noted in patients treated prior to 1980 (POR=2.03; 95% CI=0.55, 7.61), treated with antifungal monotherapy (POR=1.49; 95% CI=0.39, 5.81), infected with Candida parapsilosis (POR=1.51; 95% CI=0.41, 5.52), or with left-sided endocarditis (POR=2.36; 95% CI=0.55, 10.07).

CONCLUSIONS

Medical antifungal therapy of Candida IE is poorly characterized, and recent antifungal developments lend promise for those patients who cannot undergo surgery.

Fungal endocarditis

Recent advances in medicine have caused fungal endocarditis (FE) to be a more common disease entity. Many fungi are potential pathogens in FE, although Candida species and Aspergillus species are the most common. Valvular heart disease is the necessary underlying condition for FE, with intravenous devices and antibiotic use being the predisposing factors for yeast endocarditis, whereas immunosuppression in patients with valvulopathy predisposes for mold endocarditis. Better prognosis of FE depends on fast and accurate diagnosis and subsequent treatment. Echocardiography was the most valuable recent technique in the past two decades that allowed early diagnosis of FE and is probably responsible for the improved prognosis of patients with FE. In the future, development of nonculture-based diagnostic tests may further improve the sensitivity, specificity, and rapidity of microbiologic diagnosis of FE. Novel approaches in treatment, such as new antifungal drugs, also may assist in achieving cure and further improving the prognosis of this disease entity.

Candida albicans endocarditis diagnosed by PCR-based molecular assay in a critically ill pediatric patient

A young Down's syndrome patient developed tricuspid valve endocarditis several years after undergoing surgical closure of a congenital ventricular septal defect. Fungal etiology was established by PCR amplification of the Candida albicans ERG11 gene. Although antifungal therapy was administered, surgical replacement of the infected valve was required to eliminate the infection.

Fungal endocarditis, 1995-2000

One hundred fifty-two cases of fungal endocarditis (FE) were identified in the English-language literature between January 1, 1995, and June 30, 2000. Although the median age of patients (44 years) was relatively young, injection drug use was identified as a risk factor in only 4.1% of cases. Other factors, including underlying cardiac abnormalities (47.3%), prosthetic valves (44.6%), and central venous catheters (30.4%), were more commonly identified as predisposing conditions and reflect the changing epidemiology of the syndrome. Unfortunately, mortality remains unacceptably high, particularly for patients with Aspergillus-related FE. Novel therapies are needed to improve patient outcomes.

The ins and outs of DNA fingerprinting the infectious fungi

DNA fingerprinting methods have evolved as major tools in fungal epidemiology. However, no single method has emerged as the method of choice, and some methods perform better than others at different levels of resolution. In this review, requirements for an effective DNA fingerprinting method are proposed and procedures are described for testing the efficacy of a method. In light of the proposed requirements, the most common methods now being used to DNA fingerprint the infectious fungi are described and assessed. These methods include restriction fragment length polymorphisms (RFLP), RFLP with hybridization probes, randomly amplified polymorphic DNA and other PCR-based methods, electrophoretic karyotyping, and sequencing-based methods. Procedures for computing similarity coefficients, generating phylogenetic trees, and testing the stability of clusters are then described. To facilitate the analysis of DNA fingerprinting data, computer-assisted methods are described. Finally, the problems inherent in the collection of test and control isolates are considered, and DNA fingerprinting studies of strain maintenance during persistent or recurrent infections, microevolution in infecting strains, and the origin of nosocomial infections are assessed in light of the preceding discussion of the ins and outs of DNA fingerprinting. The intent of this review is to generate an awareness of the need to verify the efficacy of each DNA fingerprinting method for the level of genetic relatedness necessary to answer the epidemiological question posed, to use quantitative methods to analyze DNA fingerprint data, to use computer-assisted DNA fingerprint analysis systems to analyze data, and to file data in a form that can be used in the future for retrospective and comparative studies.

Early onset prosthetic valve endocarditis: the Cleveland Clinic experience 1992-1997

BACKGROUND

We reviewed all cases of early onset prosthetic valve endocarditis (EO-PVE) occurring less than 12 months after valve operation among 7,043 patients undergoing heart valve replacements or repairs at The Cleveland Clinic between 1992 and 1997.

METHODS

Cases were defined by the Duke criteria and identified through prospective surveillance.

RESULTS

Seventy-seven cases of EO-PVE were identified (1 per 100 procedures), and during the study period the incidence of EO-PVE decreased from 1.5% (1992 to 1994) to 0.7% (1995 to 1997) (p < 0.01). The incidence of EO-PVE for rings (0.2%; 4 of 1,992) was significantly lower than for mechanical (1.6%; 28 of 1,731) and bioprosthetic valves (1.1%; 41 of 3,320) (p < 0.001). The incidence of EO-PVE was also significantly lower for mitral valve versus aortic valve surgeries (0.6% versus 1.4%, p < 0.001). The most common pathogens causing EO-PVE were coagulase-negative staphylococci (52%), fungi (13%), Staphylococcus aureus (10%), and enterococci (8%). Patients undergoing combined surgical and medical treatment of EO-PVE had a significantly higher 30-day, 2-year, and 3-year survival than medically treated patients, although patients judged to be too ill to survive surgery accounted for two-thirds of the patients treated medically.

CONCLUSIONS

There is a 1% incidence rate of EO-PVE among patients undergoing valve operations at our institution, usually caused by coagulase-negative staphylococci, and combined surgical and medical treatment is associated with improved survival compared with medical treatment alone.

The ins and outs of DNA fingerprinting the infectious fungi

DNA fingerprinting methods have evolved as major tools in fungal epidemiology. However, no single method has emerged as the method of choice, and some methods perform better than others at different levels of resolution. In this review, requirements for an effective DNA fingerprinting method are proposed and procedures are described for testing the efficacy of a method. In light of the proposed requirements, the most common methods now being used to DNA fingerprint the infectious fungi are described and assessed. These methods include restriction fragment length polymorphisms (RFLP), RFLP with hybridization probes, randomly amplified polymorphic DNA and other PCR-based methods, electrophoretic karyotyping, and sequencing-based methods. Procedures for computing similarity coefficients, generating phylogenetic trees, and testing the stability of clusters are then described. To facilitate the analysis of DNA fingerprinting data, computer-assisted methods are described. Finally, the problems inherent in the collection of test and control isolates are considered, and DNA fingerprinting studies of strain maintenance during persistent or recurrent infections, microevolution in infecting strains, and the origin of nosocomial infections are assessed in light of the preceding discussion of the ins and outs of DNA fingerprinting. The intent of this review is to generate an awareness of the need to verify the efficacy of each DNA fingerprinting method for the level of genetic relatedness necessary to answer the epidemiological question posed, to use quantitative methods to analyze DNA fingerprint data, to use computer-assisted DNA fingerprint analysis systems to analyze data, and to file data in a form that can be used in the future for retrospective and comparative studies.

Pre-transplantation testing: who, when and why?

An ever-widening range of human organs and tissues is being transplanted, limited currently only by the ingenuity of surgeons and immunologists to overcome the physical and immune barriers. Microbiologists are in danger of being left behind. Although the major infective risks of human organ transplantation are now well understood, many details remain controversial, and the special risks associated with tissue banking have received little attention until recently. What should we do? Are we making mountains out of molehills? Are there any data on which to base a rational decision? Topics covered include: bacteriology of cadaveric heart valve transplantation (why are valves not cultured and only dunked in antibiotic solution for 24h, whereas endocarditis gets treated for 4 weeks?); screening for tissue-born viruses (why does everyone persist with serology when genomic methods are so much better?); screening organ donors for CMV (surely we should use the optimally sensitive combination of methods?); peripheral blood stem cell transplants (should we culture these, and what do the positive results mean if we do?); donor sputum screening before heart-lung transplantation (does this aid the post-operative management of the recipient?). With active participation from the floor some areas of consensus were identified and topics worthy of scientific investigation in the future were highlighted.