Emergence of quinolone resistance among viridans group streptococci isolated from the oropharynx of neutropenic peripheral blood stem cell transplant patients receiving quinolone antimicrobial prophylaxis

In neutropenic patients receiving quinolone prophylaxis, bacteremia with viridans group streptococci resistant to quinolones is a known complication. The frequency of occurrence of quinolone-resistant organisms colonizing the oropharynx during antibacterial prophylaxis with a quinolone is not well defined. In 48 patients undergoing hematopoietic stem cell transplantation, the prevalence of quinolone resistance in viridans group streptococci colonizing the oropharynx before and during antibacterial prophylaxis with gatifloxacin or moxifloxacin (most with concomitant penicillin) was determined. For quinolone-resistant isolates, mutations in the genes gyrA and parC, which confer resistance to quinolones, were analyzed. Seventy-four isolates before and 27 isolates during quinolone use were recovered from patients' oropharynxes. The numbers of susceptible isolates recovered before versus during quinolone use were as follows: 52 (70%) versus three (11%) for ciprofloxacin, 66 (89%) versus eight (30%) for levofloxacin, 66 (89%) versus ten (37%) for gatifloxacin, and 67 (91%) versus 11 (41%) for moxifloxacin (p<0.0001). Mutations in gyrA and/or parC were detected in quinolone-resistant isolates. Quinolone-resistant viridans group streptococci are frequently found in the oropharynx of neutropenic patients after a brief (median, 8 days) exposure to gatifloxacin or moxifloxacin.

Mucormycosis and entomophthoramycosis: a review of the clinical manifestations, diagnosis and treatment

The class Zygomycetes is divided into two orders, Mucorales and Entomophthorales. These two orders produce dramatically different infections. Genera from the order Mucorales (Rhizopus, Mucor, Rhizomucor, Absidia, Apophysomyces, Cunninghamella and Saksenaea) cause an angioinvasive infection called mucormycosis. Mucormycosis presents with rhino-orbito-cerebral, pulmonary, disseminated, cutaneous, or gastrointestinal involvement. Immunocompromising states such as haematological malignancy, bone marrow or peripheral blood stem cell transplantation, neutropenia, solid organ transplantation, diabetes mellitus with or without ketoacidosis, corticosteroids, and deferoxamine therapy for iron overload predispose patients to infection. Mucormycosis in immunocompetent hosts is rare, and is often related to trauma. Mortality rates can approach 100% depending on the patient's underlying disease and form of mucormycosis. Early diagnosis, along with treatment of the underlying medical condition, surgery, and an amphotericin B product are needed for a successful outcome. Genera from the order Entomophthorales produce a chronic subcutaneous infection called entomophthoramycosis in immunocompetent patients. This infection occurs in tropical and subtropical climates. The genus Basidiobolus typically produces a chronic subcutaneous infection of the thigh, buttock, and/or trunk. Rarely, it has been reported to involve the gastrointestinal tract. The genus Conidiobolus causes a chronic infection of the nasal submucosa and subcutaneous tissue of the nose and face. This paper will review the clinical manifestations, diagnosis and treatment of mucormycosis and entomophthoramycosis.

Primary hepatic low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) associated with primary biliary cirrhosis

We describe a case of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) arising in the liver of a patient with early-stage primary biliary cirrhosis (PBC). The patient, a 62-year old woman, presented with abnormal liver function tests, a positive antimitochondrial antibody titer (1:160), and a liver mass. The resected mass, 6.0 x 5.0 x 4.0 cm, had the features of MALT-type lymphoma. The neoplastic cells were small lymphoid cells of B-cell lineage that surrounded reactive lymphoid follicles and infiltrated bile ductules to form lymphoepithelial lesions. The uninvolved liver had histologic evidence of early stage PBC, characterized by segmental duct destruction with granulomata and an inflammatory infiltrate in the portal triads composed of lymphocytes, plasma cells, and occasional eosinophils. A periportal lymph node showed histologic features of the hyaline-vascular type of Castleman's disease, without evidence of malignant lymphoma. Low-grade B-cell lymphomas of the MALT type rarely arise in the liver and, to our knowledge, have not been reported previously in association with PBC. The association in this case suggests that chronic antigenic stimulation as a result of PBC induced the accumulation of acquired MALT, which subsequently transformed to low-grade B-cell lymphoma.

Oxidant resistance of cadmium-adapted human lung fibroblasts

Metallothionein (MT) is a metal and thiol-rich protein readily induced by cadmium (Cd) exposure. In vitro experiments have demonstrated that MT is able to serve as a scavenger of hydroxyl radicals as well as superoxide anions, albeit to a lesser extent. The role of MT as a mediator in Cd induced oxidant resistance was investigated in a nontransformed human lung fibroblast cell line (IMR-90). Cells were passaged three times either in a Cd-containing medium (8.9 microM CdCl2) or in a medium which lacked Cd. Cellular MT content, as quantitated by a modification of the heme/109Cd binding assay, increased significantly with each passage in Cd. Immunocytochemistry studies revealed that all Cd-pretreated cells contained MT and that MT was localized in both cytoplasmic and nuclear compartments. Immunolabeling was more intense in some cells compared to others. Very slight immunolabeling was observed in physiological control cells, grown in the absence of Cd, and virtually no staining was observed in Cd-adapted or non-adapted cells when primary antibody was omitted. Using the xanthine/xanthine oxidase system as a generating system for active oxygen species, we found that the magnitude of cell injury for Cd-adapted and non-adapted fibroblasts was dependent upon oxidant concentration and duration of oxidant exposure. Cd-adapted fibroblasts, which were characterized by over-expression of MT, were significantly more resistant to injury by active oxygen species and also exhibited a greater ability to scavenge extracellular hydrogen peroxide compared to cells with no previous history of Cd exposure. Experiments with aminotriazole demonstrated that catalase was not a major contributor to the additional hydrogen peroxide scavenging capacity of Cd-adapted cells. The data presented in this report are consistent with involvement of MT in protecting critical cellular targets from reactive oxygen species.