Detection of Bloodstream Pathogens in Hematological Malignancies

* To identify the common bacterial and fungal species causing fungemia and bacteremia in hematological malignancies. * To identify sensitivity pattern for causative microbes. * Compare culture on ordinary media with Vitek2 (automated microbial identification system) and multiplex polymerase chain reaction (PCR )

Sepsis is a global health problem and an estimated 17 million cases of sepsis occur each year in the world .The early initiation of appropriate antibiotic therapy is determinant for the prognosis and survival of patients with bloodstream infections . Infections in patients suffering from hematological malignancies are a frequent problem, leading to higher mortality and morbidity, increased costs of health care and prolonged duration of hospitalization. Common among these infections are those involving the bloodstream. In febrile neutropenic patients, the attack rate of bloodstream infection was reported to be between 11 and 38% . Hematological malignancies by themselves or by their therapeutic strategies, put patients at risk for infections. Wide use of antibiotics and prophylactic agents in such patients has led to the development of resistance. The general term fungemia describes the presence of a fungal species in the blood while term bacteremia describes the presence of bacterial species in the blood A positive culture may indicate a widespread infection or commonly, the infection of an intravenous catheter .Fungal microbes are abundant in nature and are frequent colonizers on human mucosal surfaces. However, under conditions of impaired immune responses or a break in host barriers, fungi are able to invade normally sterile areas of the human body, where they can cause severe infections that are difficult to recognize and treat and are often ultimately lethal .Indeed, recent epidemiological data show that invasive fungal infections (IFIs) are frequently encountered in clinical practice, with the most common offenders, being Candida spp. and Aspergillus spp. In order to effectively eliminate these infections, early diagnosis and species identification are of paramount importance. Traditional diagnostic methods such as blood culture is still considered the gold standard .Indeed ,novel molecular and non molecular techniques have been developed and currently under clinical evaluation . The VITEK 2 is an automated microbial identification system that utilizing growth-based technology. With its colorimetric reagent cards, the VITEK 2 offers a state of the art technology platform for phenotypic identification methods. The application of the multiplex polymerase chain reaction PCR method in the diagnosis of bloodstream infections is designed to reduce the time for identification of the microorganisms grown from the positive samples to 24-48 hours, as pathogens are identified directly from a positive blood sample