Sebastiano Leone

Methicillin-resistant Staphylococcus aureus: the superbug

Over the last decade, methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged as serious pathogens in the nosocomial and community setting. Hospitalization costs associated with MRSA infections are substantially greater than those associated with methicillin-sensitive S. aureus (MSSA) infections, and MRSA has wider economic effects that involve indirect costs to the patient and to society. In addition, there is some evidence suggesting that MRSA infections increase morbidity and the risk of mortality. Glycopeptides are the backbone antibiotics for the treatment of MRSA infections. However, several recent reports have highlighted the limitations of vancomycin, and its role in the management of serious infections is now being reconsidered. Several new antimicrobials demonstrate in vitro activity against MRSA and other Gram-positive bacteria. Data from large surveys indicate that linezolid, daptomycin, and tigecycline are almost universally active against MRSA. This review will briefly discuss the epidemiology, costs, outcome, and therapeutic options for the management of MRSA infections.

Prosthetic joint infections: microbiology, diagnosis, management and prevention

Infections associated with prosthetic joints occur less frequently than aseptic failures but represent the most devastating complication, with high morbidity and substantial cost. The most important risk factors are co-morbidity and prior joint replacement (revision surgery). No single routinely used clinical or laboratory test has been shown to achieve ideal sensitivity, specificity and accuracy for the diagnosis of prosthetic joint infection (PJI). Therefore, only the sum of clinical signs and symptoms, blood tests, histopathology, radiography, bone scans and a microbiological work-up can provide an accurate diagnosis. Antimicrobial therapy must always be combined with the correct surgical treatment, which is chosen according to the duration of the infection and co-morbidities of the patient. This review will briefly discuss the microbiology, diagnosis, management and prevention of PJI.

Ultrasensitive assessment of residual low-level HIV viremia in HAART-treated patients and risk of virological failure.

Background:Low-level viremia (LLV) is measurable, with enhanced assays, in many subjects with HIV RNA levels <50 copies per milliliter. The clinical consequences of LLV are unknown. Methods:In a prospective study in HIV-1–infected adults, HIV RNA levels were determined with an ultrasensitive test (3 copies/mL) based on a real time polymerase chain reaction. The primary end point was to evaluate LLV prediction of virological failure, defined as a confirmed plasma HIV RNA level >50 copies per milliliter. Results:One thousand two hundred fourteen patients were followed for (mean) 378 days. At baseline, 71.5% were <3 copies per milliliter below the limit of detection (BLD). The risk of failing highly active antiretroviral therapy in the following 4 months for patients BLD was 0.4% compared with a 3.2% risk for those with LLV (P < 0.0001; odds ratio: 7.52). There was a significant (P < 0.0001) linear relationship between the HIV RNA and the risk of virologic failure. LLV receiver operating curve analysis showed an area under the curve of 0.76 (95% confidence interval: 0.68 to 0.84) that significantly (P < 0.0001) predicted the risk of failure. The risk of an unconfirmed viral blip was higher in patients with LLV (3.9%) than in those BLD (1.1%) (P < 0.0001; odds ratio: 3.56). Longer exposure to antiretrovirals, current use of nonnucleoside reverse transcriptase inhibitors, longer time BLD, and current HIV RNA <3 copies per milliliter were independent predictors of a positive outcome. Interpretation:Viral replication may be the cause of LLV, at least in some patients. A LLV >3 copies per milliliter is linked to a significant increment of risk of virological failure leading to drug resistance. Patients with measurable LLV should be managed to better evaluate, over time, the risk of failure and to limit its consequences.

Consensus document on controversial issues in the diagnosis and treatment of prosthetic joint infections

BACKGROUND Joint replacement surgery has been on the increase in recent decades and prosthesis infection remains the most critical complication. Many aspects of the primary prevention and clinical management of such prosthesis infections still need to be clarified. CONTROVERSIAL ISSUES The aim of this GISIG (Gruppo Italiano di Studio sulle Infezioni Gravi) working group - a panel of multidisciplinary experts - was to define recommendations for the following controversial issues: (1) Is a conservative surgical approach for the management of prosthetic joint infections effective? (2) Is the one-stage or the two-stage revision for the management of prosthetic joint infections more effective? (3) What is the most effective treatment for the management of prosthetic joint infections due to methicillin-resistant staphylococci? Results are presented and discussed in detail. METHODS A systematic literature search using the MEDLINE database for the period 1988 to 2008 of randomized controlled trials and/or non-randomized studies was performed. A matrix was created to extract evidence from original studies using the CONSORT method to evaluate randomized clinical trials and the Newcastle-Ottawa Quality Assessment Scale for case-control studies, longitudinal cohorts, and retrospective studies. The GRADE method for grading quality of evidence and strength of recommendation was applied.

Italian Guidelines for the Diagnosis and Infectious Disease Management of Osteomyelitis and Prosthetic Joint Infections in Adults

Bone and joint infections are recognized as difficult-to-treat infections that result in significant morbidity and mortality among patients and increased healthcare costs. This article presents the recommendations for the diagnosis and management of osteomyelitis and prosthetic joint infections in adults developed by Bone and Joint Infections Committee for the Italian Society of Infectious and Tropical Diseases. It contains data published through to November 2007. An evidence-based scoring system that is used by the Infectious Diseases Society of America was applied to treatment recommendations.

Immune reconstitution inflammatory syndrome associated with Mycobacterium tuberculosis infection: a systematic review

HIV and tuberculosis (TB) are leading global causes of mortality and morbidity. Highly active antiretroviral therapy (HAART) is often initiated in patients being treated for TB. The immune recovery associated with HAART results in dramatic clinical benefits, but this restoration of immunity may result in immunopathological reactions. The immune reconstitution inflammatory syndrome can result in fever, nodal enlargement, and worsening pulmonary infiltrates observed on a chest radiograph, with or without recurrent respiratory symptoms. Several other manifestations have also been described. As a consequence, the use of HAART might not be appropriate during the first weeks of anti-TB therapy in HIV-infected patients. In this review, we summarize the incidence, clinical presentations, and potential mechanisms of these conditions and we describe therapeutic methods.

Immunohistochemical distribution of proteins belonging to the receptor-mediated and the mitochondrial apoptotic pathways in human placenta during gestation

The balance between cell death and cell proliferation and its regulation are essential features of many physiological processes and are particularly important in fetal morphogenesis and adult tissue homeostasis. Apoptosis is a type of cell suicide that is activated in two main ways: through a receptor-mediated pathway or through a mitochondrial pathway. We have investigated the immunohistochemical distribution of proteins belonging to these two pathways in human placenta during gestation by comparing their expression levels between the first and third trimester of gestation. In the first trimester, the receptor-mediated pathway prevails over the mitochondrial pathway with a moderate/intense expression of its three components, viz., Fas ligand (FasL), Fas, and caspase-8, and weak positivity of anti-apoptotic FLIP, these proteins being mainly localized in the cytotrophoblast compartment. In the third trimester of gestation, there is an increased expression of mitochondrial pathway proteins, viz., Apaf-1 and caspase-9. We have also investigated the expression level of caspase-3, the primary effector caspase of both pathways, and have observed that it is moderately expressed during gestation, being mainly localized in the cytotrophoblast during the first trimester and in both placental compartments during the third trimester of gestation. Thus, both pathways actively function in human placenta to execute cell death. By means of immunoelectron microscopy, we have further shown that, in human placenta, the two proteins of the mitochondrial pathway together with caspase-3 are localized both in the cytoplasm and in the nucleus. In particular, Apaf-1 and caspase-9 are distributed near to the nuclear envelope suggesting an important role for these two proteins in disrupting the nuclear–cytoplasmic barrier.

Pattern of expression of cyclin D1/CDK4 complex in human placenta during gestation.

Progression through the cell cycle in eukaryotic cells is controlled by a family of protein kinases, termed cyclin-dependent kinases (CDKs), and their specific partners, the cyclins. In particular, the control of mammalian cell proliferation occurs largely during the G1 phase of the cell cycle. Five mammalian G1 cyclins have been enumerated to date: cyclins D1, D2, and D3 (D-type cyclins), and cyclins E and E2. By the use of immunohistochemistry and immunoelectron microscopy, we observed that in the first trimester of gestation of human placenta, cyclin D1 was distributed in the nuclei of the cytotrophoblast compartment together with a weak positivity of endothelial cells surrounding blood vessels. The endothelial positivity of cyclin D1 strongly increased in the third trimester of gestation. Moreover, we observed the subcellular localization of cyclin D1 that was present both in the stroma of placental villi and in the nuclei of syncytiotrophoblast cells. Therefore, we observed that CDK4 was localized in the nuclei of the cytotrophoblast compartment during the first and third trimesters and it also had a nuclear positivity in the endothelial cells of blood vessels at the end of the third trimester of gestation. In conclusion we may hypothesize that cyclin D1/CDK4 complex functions to regulate the cell cycle progression in the proliferative compartment of human placenta, the cytotrophoblast, during the first trimester through interaction with p107 and p130. Therefore, cyclin D1 and CDK4 seem to be involved in the control of placental angiogenesis during the third trimester of gestation.

Considerations of antibiotic therapy duration in community- and hospital-acquired bacterial infections

Despite the large number of suggestions available in the literature, the optimal duration of antibiotic treatment remains an individual decision mainly based on clinical criteria. Shorter but equally effective regimens would reduce the side effect rates, including both antibiotic resistance and drug expenses. Although several prospective, randomized trials and meta-analyses with the aim of comparing a standard duration with a shorter one for most bacterial infections have been published, to date most current recommendations carry little weight, as they are based on expert opinions or practical experience. This review will briefly touch upon the clinical evidence of short-course versus long-course antibiotic therapy for the most common community- and hospital-acquired bacterial infections.

Diagnosis and management of Skin and Soft-Tissue Infections (SSTI): a Literature Review and Consensus Statement on Behalf of the Italian Society of Infectious Diseases and International Society of Chemotherapy

Abstract Skin and soft-tissue infections (SSTIs) are among the most common bacterial infections, posing considerable diagnostic and therapeutic challenges and resulting in significant morbidity and mortality among patients as well as increased healthcare costs. Eight members of the SSTI working group of the Italian Society of infectious Diseases prepared a draft of the statements, grading the quality of each piece of evidence after a careful review of the current literature using MEDLINE database and their own clinical experience. Statements were graded for their strength and quality using a system based on the one adopted by the infectious Diseases Society of America (IDSA). The manuscript was successively reviewed by seven members of the SSTI working group of the international Society of Chemotherapy, and ultimately re-formulated by all experts. The microbiological and clinical aspects together with diagnostic features were considered for uncomplicated and complicated SSTIs. Antimicrobial therapy was considered as well —both empirical and targeted to methicillin-resistant Staphylococcus aureus (MRSA) and/or other main pathogens.