Molecular-based diagnosis of bacteremia in the setting of fever with or without neutropenia in pediatric hematology-oncology patients.

BACKGROUND: Prompt evaluation and appropriate treatment with wide-spectrum antibiotics is considered mandatory for febrile oncology patients especially during neutropenia. Central venous catheters are widely used in pediatric oncology patients and are often the source of infections. Patients are usually admitted for follow-up and administration of antibiotics. Aims were to assess the efficacy of the polymerase chain reaction (PCR) method in identifying bacteria in blood samples as compared with standard blood cultures. METHODS: This was a prospective study, which included all patients with central venous catheters admitted to the pediatric hematology-oncology department over the 14-month period. Demographic, clinical, and laboratory variables were compared in bacteremic and nonbacteremic patients. Standard microbiological cultures were compared using the PCR technique. RESULTS: From September 2004 to November 2005, 148 blood cultures (70 patients) were evaluated. Positive blood cultures were detected on 21 (18.3%) occasions. PCR had sensitivity of 46%, specificity of 98%, positive predictive value 86%, and negative predictive value 89%. The PCR identified fastidious bacteria in 2 occasions when standard cultures were negative. CONCLUSIONS: Inspite of low sensitivity, PCR may help with early identification of bacteremia. Improving this technology is warranted.

Prolonged fever and splinter hemorrhages in an immunocompetent traveler with disseminated histoplasmosis.

We present a case of progressive disseminated histoplasmosis in an immunocompetent traveler. Histoplasmosis was acquired in South America; its manifestations included prolonged fever, splinter hemorrhages, erythema multiforme, arthritis, and mediastinal lymphadenopathy. To the best of our knowledge no splinter hemorrhages had previously been reported in a patient with histoplasmosis.

Outcome of Pneumocystis jirovecii pneumonia diagnosed by polymerase chain reaction in patients without human immunodeficiency virus infection.

BACKGROUND AND OBJECTIVE: Pneumonia caused by Pneumocystis jirovecii (PCP) in patients without human immunodeficiency virus (HIV) infection is associated with high mortality. The diagnosis of PCP at our institution is based on detection of DNA using a polymerase chain reaction (PCR) assay. The aim of this study was to describe the clinical manifestations, outcomes and factors associated with mortality due to PCP, as diagnosed by PCR, in patients without HIV infection. METHODS: Over a 6-year period, all HIV-negative immunocompromised patients suspected of having an opportunistic pulmonary infection underwent diagnostic bronchoscopy. A multigene PCR assay that detects Pneumocystis jirovecii DNA was used for the diagnosis of PCP. Patients were considered to have PCP if they had underlying immunodeficiency, compatible signs and symptoms, abnormal radiological findings, and Pneumocystis jirovecii DNA was detected in a bronchoalveolar lavage fluid sample. Data was collected retrospectively. RESULTS: PCP was diagnosed in 58 patients. The underlying conditions included haematological malignancies (60.3%), solid tumours (17.2%) and immunosuppressive treatment (22.4%). The most common clinical features in patients with PCP were fever (94.6%), dyspnoea (67.2%) and cough (36.2%). The overall in-hospital mortality was 17.2% (10/58). Mortality was associated with co-infections, high lactate dehydrogenase levels, female gender, and higher pneumonia severity index and acute physiology and chronic health evaluation III scores. CONCLUSIONS: In this study, the mortality of HIV-negative patients with PCP was low compared with previous reports. We hypothesize that this finding resulted from the increased sensitivity of a PCR-based assay, as compared with traditional methods, for the diagnosis of PCP in HIV-negative patients.

Polymerase chain reaction-based detection of Pneumocystis jirovecii in bronchoalveolar lavage fluid for the diagnosis of pneumocystis pneumonia.

INTRODUCTION: The diagnosis of pneumocystis pneumonia (PCP) in non-human immunodeficiency virus (HIV)-infected immunocompromised patients is notoriously difficult. The recent advent of polymerase chain reaction (PCR)-based detection systems, based on the identification of single fungal genes, has markedly improved diagnostic accuracy in this ominous disease. In an attempt to further improve diagnostic yield, the authors used a PCR-based detection system for Pneumocystis jirovecii, based on targeting 3 distinct genes. METHODS: During the 4-year period (January 2005 to January 2009), all consecutive immunocompromised patients suspected of having PCP in the differential diagnosis underwent bronchoscopy with bronchoalveolar lavage sampling for the evaluation of the etiology of pulmonary infiltrates. Bronchoalveolar fluid was tested for the presence of a wide variety of possible etiological microorganisms. RESULTS: In a cohort of 214 immunocompromised patients (of which 198 were non-HIV immunocompromised patients) who underwent bronchoscopy with bronchoalveolar lavage for evaluation of pulmonary infiltrates, PCR correctly diagnosed PCP in 75% (42/56) compared with 14% (8/56) diagnosed by traditional stains, and increased diagnostic yield 5.4-fold. CONCLUSIONS: Given the absence of a sensitive gold standard, this study demonstrates the usefulness of a multigene PCR-based detection of Pneumocystis jirovecii DNA for supporting the clinical diagnosis of PCP, with high sensitivity and negative predictive value rates compared with direct stains, especially in non-HIV immunocompromised patients.

An outbreak of Mycobacterium mucogenicum bacteremia in pediatric hematology-oncology patients.

BACKGROUND AND AIMS: Mycobacterium mucogenicum (MM) is a rapidly growing nontuberculous mycobacterium that is commonly identified in tap water that can rarely cause bacteremia. We describe an outbreak of MM bacteremia among pediatric hematology-oncology patients. METHODS: Charts of children with MM bacteremia were retrospectively reviewed. Demographic data, underlying conditions, central venous catheter (CVC) type, duration of bacteremia, and treatment were retrieved. Epidemiologic investigation was conducted during the outbreak including environmental sampling. RESULTS: During an 8-month period (September 2005-May 2006), 8 patients aged 1.5 to 17 years had MM bacteremia. Seven patients had underlying malignancy and 1 with thalassemia major had bone marrow transplantation. The mean number of positive blood cultures was 4.2 (1-11) per patient. Two patients received antibiotic treatment in addition to removal of CVC. All patients were cured. Almost 60 environmental samples were obtained from surfaces, ice, and municipal water supply. All were negative and no source was documented. Infection control measures included emphasis on guidelines for prevention of CVC-associated infections. No cases occurred before and after this outbreak. CONCLUSIONS: MM is a rare agent of CVC-associated bacteremia. Removal of the CVC may be sufficient for management of bacteremia. In the absence of definite source identification, reinforcement of standard infection control measures can be successful in containing outbreaks.

Fatal hospital-acquired Legionella pneumonia in a neonate.

Legionnaire disease is a rare cause of community-acquired pneumonia in children and an exceedingly rare diagnosis in infants and neonates, with only few reported cases. We describe a case of fatal Legionnaire disease diagnosed by culture and polymerase chain reaction method from sputum and lung biopsy specimens, and emphasize the importance of considering this rare entity in cases of severe neonatal pneumonia.

Aspergillus vertebral osteomyelitis in chronic leukocyte leukemia patient diagnosed by a novel panfungal polymerase chain reaction method.

BACKGROUND CONTEXT: Vertebral osteomyelitis and disciitis caused by Aspergillus spp is a rare event. Early diagnosis and early antifungal therapy are critical in improving the prognosis for these patients. The diagnosis of invasive fungal infections is, in many cases, not straightforward and requires invasive procedures so that histological examination and culture can be performed. Furthermore, current traditional microbiological tests (ie, cultures and stains) lack the sensitivity for diagnosis of invasive aspergillosis. PURPOSE: To present a case of vertebral osteomyelitis caused by Aspergillus spp diagnosed using a novel polymerase chain reaction (PCR) assay. STUDY DESIGN: Case report. METHODS: Aspergillus DNA was detected in DNA extracted from the necrotic bone tissue by using a "panfungal" PCR novel method. RESULTS: Treatment with voriconazole was started based on the diagnosis. CONCLUSION: Using this novel technique enabled us to diagnose accurately an unusual bone pathogen that requires a unique treatment.

Contamination of peripheral hematopoeitic stem cell products with a Mycobacterium mucogenicum-related pathogen.

A gram-positive rod with a restriction pattern closely related to the published nucleotide sequence of Mycobacterium mucogenicum was isolated from 6 of 45 units of peripheral blood stem cell products. The source of the contamination was traced to ice cubes used in processing the peripheral blood stem cell products. Substituting reusable ice trays for ice from an ice machine terminated the outbreak.