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Biomedical subjects

V L Yu

Publications and source records attributed to V L Yu.

At least 91 records · Page 5Linked to original sources

Invasive gastrointestinal zygomycosis in a liver transplant recipient: case report and review of zygomycosis in solid-organ transplant recipients.

Zygomycosis is a rare but highly invasive fungal infection that occurs in transplant recipients. We report a case of invasive gastrointestinal zygomycosis that occurred in a heavily immunosuppressed liver transplant recipient 5 days after retransplantation and that presented as gastric perforation. Despite aggressive surgical and antifungal therapy, the patient died. We review 46 cases of invasive zygomycosis in solid-organ transplant recipients. The rhinocerebral form of zygomycosis occurred in 57% of cases; the pulmonary, cutaneous, and disseminated forms each occurred in 13%; the renal form occurred in 2%; and the gastrointestinal form occurred in 2%. The infection ensued a median of 2 months after transplantation (range, 5 days to 8 years). Seventy-six percent of the patients had diabetes or had received antirejection therapy, mainly in the form of corticosteroids, before the onset of zygomycotic infection. The mortality for patients who received antifungal therapy and/or who underwent surgery was 50% for those who had rhinocerebral zygomycosis, none for those who had pulmonary and cutaneous zygomycosis, and 100% for those who had disseminated zygomycosis. Knowledge of the diverse clinical manifestations (including gastrointestinal involvement, as is illustrated by our case) and predisposing factors in transplant recipients with zygomycosis can aid in early recognition of this disease in this patient population.

Adult↗

Meningitis caused by Candida species: an emerging problem in neurosurgical patients.

Three cases of candida meningitis were encountered in a 3-year period in our hospital; all occurred in neurosurgical patients. We describe these three cases and review the 15 cases of neurosurgery-related candida meningitis previously reported in the English-language literature. Data regarding these 18 patients formed the basis for our review. Most patients with candida meningitis had recently received antibacterial agents, and it is notable that 50% of patients suffered from antecedent bacterial meningitis. The CSF analysis revealed neutrophilic pleocytosis that was indistinguishable from that of bacterial meningitis. The overall mortality was 11%. Administration of amphotericin B combined with flucytosine appeared to be the best therapeutic approach for candida meningitis.

Adult↗

In vitro evaluation of combination of fluconazole and flucytosine against Cryptococcus neoformans var. neoformans.

Amphotericin B and fluconazole are current acceptable therapies for cryptococcal meningitis; however, their effect remains suboptimal. The combination of fluconazole and flucytosine has yielded encouraging clinical results in human immunodeficiency virus patients with cryptococcal meningitis. To investigate the biological basis of this finding, we performed in vitro combination testing of fluconazole and flucytosine against 50 clinical strains of Cryptococcus neoformans var. neoformans. Synergy (fractional inhibitory concentration index of < 1.0) was observed in 62% of cases, while antagonism (fractional inhibitory concentration index of > 2.0) was not observed. For cases in which synergy was not achieved (autonomous or additive effects), the beneficial effect of the combination was still seen (i.e., there was still a decrease, although not as dramatic, in the MIC of one or both drugs when used in combination). The in vitro inhibitory action of flucytosine was greatly enhanced by the addition of fluconazole; the flucytosine MICs for Cryptococcus isolates were markedly decreased to concentrations which were severalfold lower than the achievable cerebrospinal fluid flucytosine concentration. On the other hand, the addition of flucytosine did not greatly enhance the in vitro activity of fluconazole if the initial fluconazole MIC for the isolate was > or = 8 micrograms/ml. Controlled clinical studies are warranted to further elucidate the potential utility of fluconazole-flucytosine combination therapy.

Antifungal Agents↗

Comparison of culture methods for monitoring Legionella species in hospital potable water systems and recommendations for standardization of such methods.

A lack of standardization of environmental monitoring techniques for Legionella spp. complicates the interpretation of results and comparisons of results from different institutions. A comparative assessment of techniques recommended by the Centers for Disease Control and Prevention, the Hygiene Institute (Graz, Austria), and our laboratory was performed. Variables investigated were sampling method (swabbing and collection of water samples [250 ml] before and after swabbing), method of concentration (none, filtration, and centrifugation), acid buffer treatment (no acid treatment, treatment for 3 min, and treatment for 15 min), and choice of medium (five formulations of buffered charcoal yeast extract agar with glycine, vancomycin, polymyxin B, anisomycin, or cycloheximide). Thirty-three sites in seven hospital buildings were studied. Recovery by swab correlated with recovery from water after swabbing (P < 0.05). However, the quantity of Legionella spp. recovered from swab specimens (mean, 3.0 x 10(4) CFU per swab) was greater than that recovered from water (mean, 4.7 x 10(3) CFU/250 ml). Filtration resulted in recovery rates (mean, 5.2 x 10(3) CFU/250 ml) higher than those by centrifugation (mean, 2.3 x 10(3) CFU/250 ml). Three minutes of acid buffer treatment to reduce overgrowth by commensal flora did not improve selectivity or sensitivity for Legionella spp. if glycine-containing selective media were used. Fifteen minutes of acid buffer treatment reduced recovery compared with that after a 3-min treatment. All glycine-containing media tested effectively inhibited background flora, but one selective medium containing dyes, glycine, vancomycin, and polymyxin B (DGVP) resulted in the greatest quantitative recovery of Legionella pneumophila. Use of buffered charcoal yeast extract agar and the acid buffer treatment gave the greatest recovery of non-pneumophila species. A standardized protocol with an emphasis on the culturing of swab samples is presented.

Bacteriological Techniques↗

Necrotizing (malignant) external otitis: prospective comparison of CT and MR imaging in diagnosis and follow-up.

PURPOSE: To compare computed tomography (CT) and magnetic resonance (MR) imaging in the diagnosis and follow-up of necrotizing external otitis. MATERIALS AND METHODS: CT and MR imaging were performed in seven patients at diagnosis and at 6 and 12 months after initiation of therapy. Imaging findings were compared and correlated with the clinical course of the disease. RESULTS: Cortical bone erosion was best seen on CT scans (n = 5 vs n = 0 on MR images) and failed to normalize with cure. Subtemporal soft-tissue abnormalities (n = 7 with both modalities) were better appreciated with MR imaging and had low signal intensity on T1- and T2-weighted images. Soft-tissue changes improved but did not disappear completely with treatment. CONCLUSION: CT is preferred at initial diagnosis, as small cortical erosions are better seen. Either modality can be used to follow up soft-tissue evolution. MR imaging may be better for evaluation and follow-up of meningeal enhancement and changes within the osseous medullary cavity.

Aged↗

Infectious complications in liver transplant recipients on tacrolimus. Prospective analysis of 88 consecutive liver transplants.

This prospective study characterizes the incidence, etiology, timing, risk factors, and outcome of the infectious complications after 88 consecutive liver transplantations in 79 patients receiving tacrolimus (FK506) as primary immunosuppression with a median follow-up of 880 days. Infections occurred in 59% (47/79) of the patients, and 39% had major infections. Of the major infections, 55% were bacterial, 22% were viral, and 22% were fungal. Bacteremia accounted for 30% of major bacterial infections. Sixty percent of bacteremias occurring within the first 3 months were catheter related, while 75% of those occurring more than 3 months after transplant were of a biliary source. Patients with recurrent hepatitis C virus hepatitis and patients requiring dialysis after transplant had a significantly higher rate of infections as compared with other patients. Overall mortality was 18%, and 29% of all deaths were associated with infection. Only invasive aspergillosis was associated with infectious mortality. Our data suggest that the potent immunosuppressive agent FK506 is not associated with a higher incidence of infectious complications as compared with previous studies using CsA.

Adult↗

High-dose acyclovir compared with short-course preemptive ganciclovir therapy to prevent cytomegalovirus disease in liver transplant recipients. A randomized trial.

OBJECTIVE: To assess the efficacy of high-dose oral acyclovir therapy compared with preemptive, short-course ganciclovir therapy (administered only if cytomegalovirus [CMV] shedding occurred) to prevent CMV disease in liver transplant recipients. DESIGN: A randomized controlled trial. SETTING: Liver transplant center at a university-affiliated Veterans Affairs Medical Center. PATIENTS: 47 consecutive patients having liver transplantation. INTERVENTION: Patients were stratified by their CMV antibody status and the CMV antibody status of the donor and were randomly assigned to one of two treatment groups. Surveillance cultures for CMV (buffy coat and urine) were done every 2 to 4 weeks for 24 weeks in all patients. One group received high-dose oral acyclovir (800 mg four times daily). The experimental group received no acyclovir, but if surveillance cultures were positive, ganciclovir (5 mg/kg intravenously twice daily) was administered for 7 days. MEASUREMENTS: Cytomegalovirus shedding and CMV disease were measured in the two groups. RESULTS: Cytomegalovirus shedding before the onset of CMV disease occurred in 25% (6 of 24) of patients in the acyclovir group compared with 22% (5 of 23) in the experimental group. Cytomegalovirus disease developed in 29% (7 of 24) of the acyclovir group and in 4% (1 of 23) of the experimental group (P < 0.05). No hematologic toxicity occurred with ganciclovir. CONCLUSION: Oral acyclovir is ineffective prophylaxis against CMV in liver transplant recipients. Preemptive, short-course ganciclovir therapy in patients with CMV shedding was well tolerated and provided effective prophylaxis against subsequent CMV disease; this protocol targets the patients at risk for CMV disease and minimizes toxicity and expense.

Acyclovir↗

Decreased incidence of viral infections in liver transplant recipients. Possible effects of FK506?

Cytomegalovirus (CMV) is a major infectious complication of organ transplantation and its incidence is influenced by the type and intensity of immunosuppressive therapy employed. Using a new immunosuppressive agent FK506, CMV infection was observed in 30% and CMV disease in 15% of the 26 liver transplant recipients. Delayed onset of CMV disease was noted; the mean time to the occurrence of CMV disease being 137 days posttransplantation. No graft loss or mortality could be attributed to CMV infection. Mucocutaneous herpes simplex virus (HSV) infections were encountered in 19% of the patients, while no disease could be attributed to varicella zoster virus or Epstein-Barr virus (EBV). The contribution of FK506 to a decrease in viral morbidity and associated mortality bears further investigation.

Cytomegalovirus Infections↗

Listeria monocytogenes peritonitis in cirrhotic patients. Value of ascitic fluid gram stain and a review of literature.

Listeria monocytogenes has been increasingly implicated in spontaneous bacterial peritonitis in patients with cirrhosis. This bacterium can be mistaken for diphtheroids and gram-positive cocci if special attention is not paid to the motility pattern and specific biochemical tests. Although the sensitivity of ascitic fluid Gram stain is low, we describe a case in which the Gram stain of the ascites fluid was positive. This issue is now pertinent given recent recommendations of third-generation cephalosporin antibiotics as empiric therapy for spontaneous bacterial peritonitis; Listeria is resistant to cephalosporin agents. A positive Gram stain could affect the empiric antibiotic therapy. We review the clinical presentation and outcome in nine other cases of Listeria peritonitis occurring in cirrhotic patients.

Aged↗

Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only.

The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate.

Adult↗

Epidemiologic perspectives on Enterobacter for the infection control professional.

Enterobacter species have emerged as important nosocomial pathogens. Common reservoirs for these organisms include wounds and the gastrointestinal, urinary, and respiratory tracts. Enterobacter bacteremia typically occurs in patients with long-standing underlying illnesses who received antimicrobial agents before their bacteremia. The wide use of broad-spectrum antibiotics has contributed to the increased prominence of Enterobacter infections. Enterobacter species have a propensity to emerge resistant to the antibiotic therapy administered. Plasmid analysis, restriction endonuclease analysis of total cellular DNA, pulsed-field electrophoresis, and ribotyping can be valuable in investigating the spread of antibiotic-resistant strains.

Anti-Bacterial Agents↗

Improved detection of spontaneous bacterial peritonitis with Bactec as compared with conventional culture methods. A prospective study.

Bacteriologic diagnosis of spontaneous bacterial peritonitis is difficult due to the low yield of isolating the bacteria from the ascitic fluid. We prospectively compared the conventional culture method with the nonradiometric Bactec culture system for the detection of bacteria in 20 episodes of spontaneous bacterial peritonitis. The ascitic fluid culture was positive by the conventional culture method in 25% and by Bactec in 79% of the episodes of spontaneous bacterial peritonitis (P = 0.004). Of culture-positive episodes, Gram-negative bacteria were detected by conventional cultures in 20% and by Bactec in 47%. Bactec culture system was significantly better than the conventional cultures for the detection of streptococci (viridans streptococci and Enterococcus fecalis), 33% versus 0 (P < 0.05). Conventional cultures did not detect bacteria that were not also detected by Bactec cultures. In conclusion, the Bactec nonradiometric culture method is superior to conventional cultures for the diagnosis of spontaneous bacterial peritonitis.

Ascitic Fluid↗

Intraocular candidiasis in patients with candidemia. Clinical implications derived from a prospective multicenter study.

PURPOSE: Intraocular infection caused by Candida species can have devastating visual consequences. With the emergence of Candida as a major nosocomial pathogen, the authors investigated the prevalence of ocular lesions in patients with candidemia and evaluated risk factors for eye involvement. METHODS: This study is a prospective, multicentered, observational design. One hundred eighteen patients with candidemia were evaluated by the infectious disease service and received indirect ophthalmologic examination within 72 hours of a reported positive blood culture. Ocular findings were classified on the basis of objective, pre-determined criteria. Candida chorioretinitis was defined as the presence of focal, white, infiltrative chorioretinal lesions without vitreal involvement. Candida endophthalmitis was defined as chorioretinitis with extension into the vitreous or intravitreal "fluff balls." RESULTS: In contrast to previous studies of patients with candidemia citing prevalence rates of endophthalmitis approaching 40%, no patients were shown to have endophthalmitis. Candida chorioretinitis was seen in 9% of the patients, all of whom received antifungal agents. The observation that chorioretinitis never progressed to endophthalmitis suggests that systemic antifungal agents provided adequate ocular therapy. Risk factors for Candida chorioretinitis include fungemia with Candida albicans (versus nonalbicans species), multiple positive blood cultures, visual symptoms, and immunosuppression. Twenty percent of patients had nonspecific ocular lesions not directly related to infection. CONCLUSION: Patients with candidemia who have the risk factors noted above warrant formal ophthalmologic examination.

Adolescent↗

Controlled evaluation of copper-silver ionization in eradicating Legionella pneumophila from a hospital water distribution system.

A controlled evaluation was made of the efficacy of copper-silver ionization in eradicating Legionella pneumophila from a hospital water supply. Copper-silver ionization units were installed on the hot water recirculation line of one building with water fixtures positive for Legionella species. Another building with the same water supply served as a control. Legionella species persisted within the system when copper and silver concentrations were < 0.3 and < 0.03 ppm, respectively. When copper and silver concentrations were > 0.4 and > 0.04 ppm, respectively, there was a significant decrease in Legionella species colonization, but the percentage of water fixtures positive for organisms was unchanged in the control building. When the ionization unit was inactivated, water fixtures continued to be free of Legionella species for 2 additional months. Copper-silver ionization can eradicate L. pneumophila in a water distribution system. The advantages of copper-silver ionization include relatively low cost, straightforward installation, easy maintenance, nontoxic by-products and the presence of a disinfecting residual.

Copper↗

Efficacy of topical amoxicillin plus clavulanate/ticarcillin plus clavulanate and clindamycin in contaminated head and neck surgery: effect of antibiotic spectra and duration of therapy.

This prospective, randomized trial was designed to determine the efficacy and mechanism of action of topical mouthwash versus parenterally administered perioperative prophylactic antibiotics in contaminated head and neck surgery. Patients were randomly assigned to 1 of 4 treatment groups: 1 day of parenteral clindamycin (standard prophylaxis), 1 day of topical clindamycin, 5 days of topical clindamycin, or 1 day of topical amoxicillin plus clavulanate/ticarcillin plus clavulanate. Patients who received the latter regimen had fewer bacteria postoperatively compared with the other 3 treatment groups. The number of gram-negative aerobic bacilli on postoperative oral cavity cultures was increased in all 3 clindamycin groups but not in the amoxicillin plus clavulanate/ticarcillin plus clavulanate group. Parenteral clindamycin appears to exert its effect by being in the neck tissues at the time of surgery; however, all 3 topical regimens were more effective at reducing the number of bacteria in the neck viscera. Topical antibiotic prophylaxis was simple, safe, effective, and well tolerated.

Amoxicillin↗