Quantitative analysis and molecular fingerprinting of methicillin-resistant Staphylococcus aureus nasal colonization in different patient populations: a prospective, multicenter study

OBJECTIVES

To better understand the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection in different patient populations, to perform quantitative analysis of MRSA in nasal cultures, and to characterize strains using molecular fingerprinting.

DESIGN

Prospective, multicenter study.

SETTING

Eleven different inpatient and outpatient healthcare facilities.

PARTICIPANTS

MRSA-positive inpatients identified in an active surveillance program; inpatients and outpatients receiving hemodialysis; inpatients and outpatients with human immunodeficiency virus (HIV) infection; patients requiring cardiac surgery; and elderly patients requiring long-term care. METHODS. Nasal swab samples were obtained from January 23, 2006, through July 27, 2007; MRSA strains were quantified and characterized by molecular fingerprinting.

RESULTS

A total of 444 nares swab specimens yielded MRSA (geometric mean quantity, 794 CFU per swab; range, 3-15,000,000 CFU per swab). MRSA prevalence was 20% for elderly residents of long-term care facilities (25 of 125 residents), 16% for HIV-infected outpatients (78 of 494 outpatients), 15% for outpatients receiving hemodialysis (31 of 208 outpatients), 14% for inpatients receiving hemodialysis (86 of 623 inpatients), 3% for HIV-infected inpatients (5 of 161 inpatients), and 3% for inpatients requiring cardiac surgery (6 of 199 inpatients). The highest geometric mean quantity of MRSA was for inpatients requiring cardiac surgery (11,500 CFU per swab). An association was found between HIV infection and colonization with the USA300 or USA500 strain of MRSA (P < or = .001). The Brazilian clone was found for the first time in the United States. Pulsed-field gel electrophoresis patterns for 11 isolates were not compatible with known USA types or clones.

CONCLUSION

Nasal swab specimens positive for MRSA had a geometric mean quantity of 794 CFU per swab, with great diversity in the quantity of MRSA at this anatomic site. Outpatient populations at high risk for MRSA carriage were elderly residents of long-term care facilities, HIV-infected outpatients, and outpatients receiving hemodialysis.

Pulmonary Phialemonium curvatum phaeohyphomycosis in a Standard Poodle dog

Phialemonium curvatum, frequently misidentified as an Acremonium species, is reported here as a new agent of pulmonary phaeohyphomycosis in a Standard Poodle dog, and added as a new species in the genus to cause mycoses in canines. In vitro susceptibility data, for both human and animal isolates, suggests resistance to amphotericin B and susceptibility to the triazole agents itraconazole, voriconazole, and posaconazole.

Interaction and regulation of macrophage receptors

Macrophages express distinct plasma membrane receptors for different isotypes of immunoglobulin, bear at least two receptors for cleaved third complement component (CR1 and CR3) and have a lectin-like receptor that mediates endocytosis of glycoproteins or glycoconjugates with terminal mannose or fucose residues (MFR). Interferon-gamma, a macrophage-activating factor, induces effects common to other interferons as well as having unique effects on cell function. The down-regulation of MFR, induction of IgG2a Fc receptors and Class II antigens and enhanced production of superoxide and hydrogen peroxide can be considered interferon-gamma-specific effects on macrophages. Previous reports described synergism of various interferon preparations in anticellular and antiviral effects. However, interferon-alpha/beta can selectively antagonize the down-regulation of macrophage MFR by interferon-gamma. The macrophage MFR and CR3 also play a synergistic role in the uptake of zymosan and Leishmania donovani in the absence of serum. The receptors may act independently or in concert. Cleaved third complement components can be specifically eluted from zymosan particles in the absence of exogenous complement and are derived from the macrophages themselves. These studies indicate a role for macrophage complement in local opsonization of pathogens at extravascular sites and focus on the role of the tissue macrophage in first-line host defence.

Localization and function of tissue macrophages

The rat monoclonal antibody F4/80 defines a plasma membrane glycoprotein of about 160 kilodaltons that is expressed by mature mouse macrophages. The antigen has been used to define macrophage distribution within the mouse (normal adult, embryo, infection models) by cytochemistry and quantitative immunochemical analysis. Macrophages migrate into fetal and adult haemopoietic and other tissues in an ordered sequence. The surface properties of 'fixed' macrophages isolated from various organs (bone marrow, liver, spleen) are distinct from those of circulating monocytes or free cells (peritoneal and pleural cavities, alveolar) and may play a role in local adhesion and trophic interactions with other cells.

Improving communication among the HLA typing laboratories, transplant centers, and coordinating center

Good communication between the bone marrow registries, the donor centres, tissue typing laboratories and clinical units is paramount to ensure timely identification, testing and selection of donors for unrelated bone marrow transplants. This panel session focussed on how to improve communication so that there was a clear understanding of prioritization of requests from clinicians, typing strategies in the laboratories and requests for donors to the registries. This paper outlined some of the strategies discussed in this session.

Renal Disease Burden Following Liver Transplantation

Significant chronic kidney disease (CKD) occurs following orthotopic liver transplant (OLT). Since CKD is associated with increased cardiovascular events, mortality, and hepatic allograft dysfunction, early recognition of CKD and implementation of changes may improve the long-term outcome. The purpose of this study was to determine the burden of renal disease following OLT.

PATIENTS AND METHODS

We retrospectively reviewed our OLT recipients from 1997 until 2004. We calculated glomerular filtration rates (GFR) using the Modification of Diet in Renal Disease study (MDRD) method. The GFRs were further subdivided into pre-MELD and post-MELD eras.

RESULTS

During the study period, we performed 407 OLTs. We censored data from living donor liver transplants (n = 14), combined liver-kidney transplants (n = 12), and from patients whom we did not have complete data for 6 months after transplant (n = 40). Mean MELD score at the time of transplant was 18 +/- 7 (mean +/- standard deviation). The mean GFR at 6 months following OLT was 63.7 +/- 30.2 mL/min per 1.73 m(2). Only 14% (n = 47) of our patients had normal renal function at 6 months, while 78% (n = 266) of our patients had mild to moderate risk for renal failure. Eight percent (n = 28) had stage 4 or 5 CKD. There were no differences between the pre-MELD and post-MELD GFRs.

CONCLUSIONS

The burden of renal disease is significant in our patient population at 6 months posttransplantation. It may be important to introduce CKD management as early as 6 months after transplant to impact the outcomes of OLT recipients.

Elevated serum B-Lymphocyte activating factor (BAFF) in chronic hepatitis C virus infection: association with autoimmunity

In this study we aimed to determine whether serum B-lymphocyte activating factor (BAFF) level is increased in patients with chronic hepatitis C virus (HCV) infection, and to assess its association with HCV-related autoimmunity. Sixty-five patients with chronic HCV infection were compared with two disease control groups [57 patients with systemic lupus erythematosus (SLE) and 15 with chronic hepatitis B virus (HBV) infection] and a healthy control group of 35 individuals. A special attention was given to HCV-related arthralgia and or vasculitis. Serum BAFF was assessed in all studied individuals, whereas rheumatoid factor (RF), anti-cardiolipin antibodies (aCL), and cryoglobulins were determined in HCV and HBV infected patients, and anti-dsDNA antibodies and aCL were assessed in patients with SLE. Mean serum BAFF was increased in patients with HCV infection and SLE (2.4+/-0.8 ng/ml and 3.1+/-1.34 ng/ml respectively) compared to 1.1+/-0.14 ng/ml in patients with HBV; and to 1.1+/-0.27 in healthy controls (all, p<0.0001). The elevation in serum BAFF was associated with HCV-related arthralgia and or vasculitis (p<0.0001), and with the presence of aCL and of cryoglobulins. HBV patients lacked features suggestive of autoimmunity. In SLE patients, elevated serum BAFF was in association with the presence of anti-dsDNA (p=0.002). As in other autoimmune diseases, increased serum BAFF was also found in patients with chronic HCV infection. Elevated serum BAFF levels were associated with clinical and laboratory features of autoimmunity, suggesting that BAFF may play a role in HCV-related autoimmunity.

Nutritional Outcomes Following Pediatric Intestinal Transplantation

BACKGROUND

This study sought to describe the long-term nutritional outcomes of children after intestinal transplant (SBT).

METHODS

Between 1991 and March 2005, 30 children received 33 SBT at a single center. Eligibility criteria included patient and graft survival >6 months. Weight, height, albumin, prealbumin, zinc (Zn), and essential fatty acid (EFA) levels were reviewed retrospectively.

RESULTS

The 19 patients who met inclusion criteria had a median age at SBT of 2.9 years. The majority of patients were male, Latino, transplanted for necrotizing enterocolitis and received combined liver-SBT. All patients were weaned off total parenteral nutrition to elemental formula at a mean of 39 days post-SBT. Seventeen of 19 patients were Zn deficient and four patients were EFA deficient post-SBT.

CONCLUSIONS

Pre-SBT most subjects were significantly deficient in anthropometric and biochemical parameters. Post-SBT the mean Z score for weight and height improved significantly at year 1, then leveled off in year 2. Serum protein levels improved from pre-SBT, yet remained low-normal. Zn deficiency was seen frequently after SBT and is under investigation. Children who developed EFA deficiency were on the same formula, receiving inadequate EFA supplementation. Successful SBT was associated with growth and maintenance of serum nutritional parameters but not with significant catch-up growth.

Comparison of the use of cefepime (cefp) monotherapy vs. piperacillin/tazobactam (pip/tazo) plus a fluroquinolone or aminoglycoside for the empiric treatment of febrile neutropenia (FN)

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Background: Practice guidelines for empiric therapy of FN were created and implemented at our institution in January 2003, prior to which empiric therapy often included the use of cefp. These guidelines recommend the combination of pip/tazo with gentamicin or levofloxacin for most patients. This retrospective chart review compared the efficacy of pip/tazo combination therapy versus historical controls treated with cefp. Methods: 183 patients met eligibility criteria. 87 patients were treated with pip/tazo, with 92% receiving levofloxacin as the second agent. 75 patients received cefp, 16 of which initially also received either a fluoroquinolone or an aminoglycoside. Endpoints included a difference in the addition of vancomycin and antifungals, incidence of breakthrough infections, trends in antibiotic resistance, and survival until discharge. Groups were compared using chi-square or Student’s t-test as appropriate. Results: The two groups were not significantly different in any measured demographic or clinical characteristic. No statistical difference was found between groups for the addition of vancomycin (cefp 43%, pip/tazo 41%; p = 0.9898) or antifungals (cefp 45%, pip/tazo 51%; p = 0.1346). The incidence of breakthrough infections was comparable (cefp 25%, pip/tazo 26%; p = 0.7461), and microorganism eradication rates were not different between groups (cefp 48%, pip/tazo 54%; p = 0.41). However, of those who developed a breakthrough infection, survival was lower in the cefp group (37% vs. 63%; p = 0.0389). Additionally, the rate of overall survival to discharge was significantly lower in patients initially treated with cefp (83% vs. 94%; p = 0.0193). The antibiograms of the hematology floors were compared for the 2 years prior to and after implementation of our FN guidelines; no change in susceptibilities was observed. Conclusions: From these results, we conclude that pip/tazo combination therapy is a reasonable alternative to cefp for empiric treatment of FN.

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Dissociation of kappa- and lambda-chains from reduced human immunoglobulins

1. The light chains of human immunoglobulin (Ig) exist in two forms, kappa (type K) and lambda (type L). The two types of chains can be partially separated by taking advantage of the fact that lambda-chains, for the most part, dissociate from reduced Ig at higher pH than do the kappa-chains. The same difference in dissociation of type K and L chains was observed with myeloma IgG and IgA proteins, but not with pathological IgM proteins. 2. When analysed in urea-glycine starch gels, pH7, both kappa- and lambda-chains show ten electrophoretic bands having the same mobilities as those of the whole light-chain subfractions. Normal kappa- and lambda-chains show similar differences in overall amino acid composition to those previously found with myeloma kappa- and lambda-chains and type K and L Bence-Jones proteins.

Transcription factor YY1: structure, function, and therapeutic implications in cancer biology

The ubiquitous transcription factor Yin Yang 1 (YY1) is known to have a fundamental role in normal biologic processes such as embryogenesis, differentiation, replication, and cellular proliferation. YY1 exerts its effects on genes involved in these processes via its ability to initiate, activate, or repress transcription depending upon the context in which it binds. Mechanisms of action include direct activation or repression, indirect activation or repression via cofactor recruitment, or activation or repression by disruption of binding sites or conformational DNA changes. YY1 activity is regulated by transcription factors and cytoplasmic proteins that have been shown to abrogate or completely inhibit YY1-mediated activation or repression; however, these mechanisms have not yet been fully elucidated. Since expression and function of YY1 are known to be intimately associated with progression through phases of the cell cycle, the physiologic significance of YY1 activity has recently been applied to models of tumor biology. The majority of the data are consistent with the hypothesis that YY1 overexpression and/or activation is associated with unchecked cellular proliferation, resistance to apoptotic stimuli, tumorigenesis and metastatic potential. Studies involving hematopoetic tumors, epithelial-based tumors, endocrine organ malignancies, hepatocellular carcinoma, and retinoblastoma support this hypothesis. Molecular mechanisms that have been investigated include YY1-mediated downregulation of p53 activity, interference with poly-ADP-ribose polymerase, alteration in c-myc and nuclear factor-kappa B (NF-kappaB) expression, regulation of death genes and gene products, and differential YY1 binding in the presence of inflammatory mediators. Further, recent findings implicate YY1 in the regulation of tumor cell resistance to chemotherapeutics and immune-mediated apoptotic stimuli. Taken together, these findings provide strong support of the hypothesis that YY1, in addition to its regulatory roles in normal biologic processes, may possess the potential to act as an initiator of tumorigenesis and may thus serve as both a diagnostic and prognostic tumor marker; furthermore, it may provide an effective target for antitumor chemotherapy and/or immunotherapy.