Penicillin-binding protein families: evidence for the clonal nature of penicillin resistance in clinical isolates of pneumococci

In view of the worldwide emergence of penicillin-resistant pneumococci among clinical isolates it was of importance to examine a large number of strains to test the uniformity of the resistance mechanism. Among 160 clinical isolates of pneumococci (minimum inhibitory concentration [MIC], 0.005-16 micrograms/mL), susceptible strains showed a common pattern of five penicillin-binding proteins (PBPs) with high penicillin affinities (PBP 3 greater than 1A greater than or equal to 2A greater than 1B greater than 2B). PBPs 1A, 2A, and 2B (but not PBP 3) each showed distinct stepwise decreases in penicillin affinities parallel with increasing levels of antibiotic resistance. The number and molecular sizes of PBPs became variable in strains with MIC values greater than 1.0 microgram/mL; among 39 strains with a MIC of greater than or equal to 1.0 microgram/mL, 11 distinct and stable PBP patterns could be identified. Using PBP profiles, serotypes, and antibiotic resistance patterns, as well as data on isolation dates and sites, we identified at least three groups of resistant strains that showed clear indication of clonal origin.     

Immunological response to highly active antiretroviral therapy in children with clinically stable HIV-1 infection

We studied changes in 60 immunological parameters after the administration of highly active antiretroviral therapy (HAART) in 192 clinically stable antiretroviral drug-experienced HIV-1-infected children 4 months-17 years old. The studied immunological parameters included standard lymphocyte subsets and lymphocyte surface markers of maturation and activation. The most significant changes during the 48-week study period were seen for CD8(+), CD8(+)CD62L(+)CD45RA(+), CD8(+)CD38(+)HLA-DR(+), and CD4(+) T cell percentages (P < .0001 for all parameters). These changes suggest that significant decreases in the expression of activation markers and increases in the expression of naive markers in the CD8(+) T cell population may be related to better virologic control in these HIV-1-infected children, who had relatively stable immune function at the initiation of HAART. At week 44 of HAART, the major immunological parameters in these HIV-1-infected children moved from baseline values to about halfway to two-thirds of the way toward the values in healthy, uninfected children.     

Predictors of Treatment Outcomes in ANCA-Associated Vasculitis with Severe Kidney Failure

Background and objectives

In ANCA-associated GN, severe renal dysfunction portends a poor prognosis for renal recovery and patient survival. This study evaluated the prognostic factors affecting renal and patient outcomes in patients presenting with severe kidney failure to guide immunosuppressive therapy.

Design, setting, participants, & measurements

This study retrospectively evaluated clinical and histopathologic characteristics of 155 patients who underwent biopsy between October 1985 and February 2011 (median eGFR at presentation, 7.1 ml/min per 1.73 m²; 87% required hemodialysis), all treated with immunosuppressive medications. Three outcomes of interest were measured: patient survival, renal survival, and treatment response (defined as dialysis-free survival without active vasculitis by 4 months after biopsy). Competing risk, Cox, and logistic regression analyses were conducted for each outcome measure.

Results

Within 4 months after biopsy, treatment response was attained in 51% of patients, 35% remained on dialysis, and 14% died. In a competing risk analysis, estimated cumulative incidence rates of ESRD and disease-related mortality were 26% and 17% at 1 year and 32% and 28% at 5 years, respectively. Cyclophosphamide therapy and treatment response by 4 months were independently associated with patient and renal survival, adjusting for the percentage of normal glomeruli, histopathologic chronicity index score, and baseline clinical characteristics. Only 5% of patients still dialysis dependent at 4 months subsequently recovered renal function. Low chronicity index score (odds ratio [OR], 1.16; 95% confidence interval [95% CI], 1.04 to 1.30, per unit decrease) and baseline eGFR>10 ml/min per 1.73 m² (OR, 2.77; 95% CI, 1.09 to 7.01) were significantly associated with treatment response by 4 months. Among cyclophosphamide-treated patients, the likelihood of treatment response was >14% even with highest chronicity index score and eGFR<10 ml/min per 1.73 m².

Conclusions

Although low baseline renal function and severe renal scarring are associated with lower treatment response rate, no “futility” threshold could be identified. Conversely, continued immunosuppressive therapy beyond 4 months is unlikely to benefit patients who remain dialysis dependent.     

Evaluation of tuberculosis diagnostics in children: 1. Proposed clinical case definitions for classification of intrathoracic tuberculosis disease. Consensus from an expert panel

There is a critical need for improved diagnosis of tuberculosis in children, particularly in young children with intrathoracic disease as this represents the most common type of tuberculosis in children and the greatest diagnostic challenge. There is also a need for standardized clinical case definitions for the evaluation of diagnostics in prospective clinical research studies that include children in whom tuberculosis is suspected but not confirmed by culture of Mycobacterium tuberculosis. A panel representing a wide range of expertise and child tuberculosis research experience aimed to develop standardized clinical research case definitions for intrathoracic tuberculosis in children to enable harmonized evaluation of new tuberculosis diagnostic technologies in pediatric populations. Draft definitions and statements were proposed and circulated widely for feedback. An expert panel then considered each of the proposed definitions and statements relating to clinical definitions. Formal group consensus rules were established and consensus was reached for each statement. The definitions presented in this article are intended for use in clinical research to evaluate diagnostic assays and not for individual patient diagnosis or treatment decisions. A complementary article addresses methodological issues to consider for research of diagnostics in children with suspected tuberculosis.     

Management of Early-stage Esophageal Neoplasia (MESEN) Consensus

Background

Treatment of esophageal adenocarcinoma often involves surgical resection. Newer technologies in interventional endoscopy have led to a substantial paradigm shift in the management of early-stage neoplasia in Barrett’s esophagus comprising high-grade dysplasia (HGD), intramucosal carcinoma, and, in some cases, submucosal carcinoma. However, there has been no consensus regarding the indications for esophageal preservation in these cases. In this work, consensus guidelines were established for the management of early-stage esophageal neoplasia considering clinically relevant aspects (age, comorbidities, and social environment) in each scenario.

Methods

Seventeen experts were invited to participate based on their background and clinical expertise at high-volume centers. A questionnaire was created that included four clinical scenarios covering a wide range of situations within HGD and/or early esophageal neoplasia, particularly where controversies are likely to exist. Each of the clinical scenarios was open to discussion subdivided by patient age (20, 50, and 80 s). For each clinical scenario an expert was chosen to defend that position. Each defense triggered a subsequent discussion during a consensus meeting. Conclusions of that discussion together with an accompanying literature analysis allowed experts to confirm or change their original choices and served as the basis for the recommendations stated in this article.

Results

There was 100 % consensus supporting esophageal preservation in patients with HGD, independent of patient age or Barrett’s length. In patients with T1a adenocarcinoma, consensus for preservation was not reached (65 %) for young and middle-aged individuals but was supported for elderly patients (100 %). For T1b adenocarcinoma, consensus was reached for surgical resection (90 %), leaving organ preservation for patients with very low risk of nodal invasion or poor surgical candidates.

Conclusion

Advances in endoscopic imaging and therapy allow for organ preservation in most settings of early-stage neoplasia of the esophagus, provided that the patient understands the implications of this decision.     

Treatment with Glucocorticoids or Calcineurin Inhibitors in Primary FSGS

Background and objectives

In primary FSGS, calcineurin inhibitors have primarily been studied in patients deemed resistant to glucocorticoid therapy. Few data are available about their use early in the treatment of FSGS. We sought to estimate the association between choice of therapy and ESRD in primary FSGS.

Design, setting, participants, & measurements

We used an inception cohort of patients diagnosed with primary FSGS by kidney biopsy between 1980 and 2012. Factors associated with initiation of therapy were identified using logistic regression. Time–dependent Cox models were performed to compare time to ESRD between different therapies.

Results

In total, 458 patients were studied (173 treated with glucocorticoids alone, 90 treated with calcineurin inhibitors with or without glucocorticoids, 12 treated with other agents, and 183 not treated with immunosuppressives). Tip lesion variant, absence of severe renal dysfunction (eGFR≥30 ml/min per 1.73 m²), and hypoalbuminemia were associated with a higher likelihood of exposure to any immunosuppressive therapy. Only tip lesion was associated with initiation of glucocorticoids alone over calcineurin inhibitors. With adjusted Cox regression, immunosuppressive therapy with glucocorticoids and/or calcineurin inhibitors was associated with better renal survival than no immunosuppression (hazard ratio, 0.49; 95% confidence interval, 0.28 to 0.86). Calcineurin inhibitors with or without glucocorticoids were not significantly associated with a lower likelihood of ESRD compared with glucocorticoids alone (hazard ratio, 0.42; 95% confidence interval, 0.15 to 1.18).

Conclusions

The use of immunosuppressive therapy with calcineurin inhibitors and/or glucocorticoids as part of the early immunosuppressive regimen in primary FSGS was associated with improved renal outcome, but the superiority of calcineurin inhibitors over glucocorticoids alone remained unproven.     

Delayed activation of quiescent donor hematopoietic stem cells in the host marrow cavity by anti-host monoclonal antibody

To understand the mechanisms controlling hematopoietic engraftment in untreated, normal recipients, we investigated the fate of parental, donor hematopoietic stem cells after apparent graft failures in unconditioned F1 hybrid recipient mice. By administering an anti-host H- 2K monoclonal antibody, which targets host cells but spares the donor, we found that chimerism could be induced by delayed conditioning in animals with apparent graft failure. Engraftment kinetics in the host were followed by typing individual colony forming unit-- granulocyte/macrophage (CFU-GM) colonies for their origin and showed that parental cells, which were otherwise virtually absent, become promptly detectable within the marrow cavity after antibody administration. Marrow transfers to secondary hosts suggested that parental stem cells were present in the marrow of the untreated recipients. These findings establish that the elimination of all parental cells cannot account for the absence of peripheral blood chimerism in the unconditioned F1 hybrid recipient. Thus, viable and functional donor stem cells, which remain quiescent in the host marrow, can be activated by a selective conditioning regimen and can rescue an apparent graft failure. The selective activation in vivo of marked stem cells in an unirradiated microenvironment may be a useful system to study the regulation of cellular proliferation within the marrow cavity.     

The effects of recombinant-DNA-derived interferons on the growth of myeloid progenitor cells

Interferons (IFNs) have been shown to have significant effects on hematopoietic cell growth. Previous studies defining these effects have utilized mouse and human alpha-, beta-, and gamma-IFN isolated from supernatants of stimulated cells. Despite purification, the possible presence of other lymphokines and soluble factors remains a concern. In this study, the effects of gene-cloned alpha- and gamma-IFN on colony- forming units of granulocyte/macrophage (CFU-GM) progenitors cultured from the peripheral blood of normal volunteers were examined. In addition, blast cell colonies from one patient with acute myelogenous leukemia (AML) were studied. The growth of normal CFU-GM and AML blast cell colonies was inhibited in a dose-dependent manner by gamma- and alpha-IFN. gamma-IFN was ten to 100 times more potent than alpha-IFN in that this species of IFN reduced colony formation by greater than 50% at concentrations of less than 15 antiviral U/mL. The effects of gamma- IFN were neutralized by a monoclonal antibody specific for gamma-IFN. These in vitro studies indicate that human gamma-IFN may be an important modulator of myelopoiesis. Although these data indicate a possible efficacy of gamma-IFN in the treatment of AML, the in vitro results should be considered for their in vivo significance.