Increased severity of pentylenetetrazol induced seizures in leptin deficient ob/ob mice

Leptin modulates multiple ion channels making its net effect on brain excitability difficult to predict. One method of determining leptin's net effect on brain excitability is to examine brain excitability during chronic leptin deficiency. We compared the susceptibility of leptin deficient ob/ob and wild type mice to pentylenetetrazol (PTZ) induced seizures using continuous video electroencephalogram (EEG) recordings. We found that ob/ob mice were more likely to die and were more susceptible to generalized clonic and clonic-tonic seizures than wild type mice at submaximal PTZ doses. These findings suggest that chronic leptin deficiency in vivo increases seizure susceptibility.     

Paecilomyces lilacinus fungemia in an adult bone marrow transplant recipient.

Paecilomyces lilacinus is a rare fungal pathogen in humans. We report a case of fungemia caused by P. lilacinus in a non-neutropenic adult, 120 days after bone marrow transplant. The patient's primary risk factor was the presence of an indwelling vascular catheter. Her initial clinical course was characterized by fever, chills, and rigors. Blood cultures from the central line and peripheral veins were positive, as was a peripheral specimen drawn after removal of the catheter. Two initial peripheral specimens were positive for P. lilacinus only by blind subculture and/or sustained incubation. She developed peripheral pulmonary nodules following the fungemia, thus raising the possibility of disseminated disease, but definitive diagnosis was confounded by Pseudomonas bacteremia. The nodules cleared and she recovered following removal of the central line and treatment with amphotericin B and 5-fluorocytosine, despite in vitro resistance to these antifungal drugs. This case underscores the increasing importance of P. lilacinus as a human pathogen capable of producing disease in immunocompetent, as well as in immunocompromised hosts. Also of note is that blood culture systems may require extended incubation or subcultures in order to detect fungi.     

Refinements of environmental assessment during an outbreak investigation of invasive aspergillosis in a leukemia and bone marrow transplant unit.

OBJECTIVES: To investigate an outbreak of aspergillosis in a leukemia and bone marrow transplant (BMT) unit and to improve environmental assessment strategies to detect Aspergillus. DESIGN: Epidemiological investigation and detailed environmental assessment. SETTING: A tertiary-care university hospital with a 37-bed leukemia and BMT unit PARTICIPANTS: Leukemic or BMT patients with invasive aspergillosis identified through prospective surveillance and confirmed by chart review. INTERVENTIONS: We verified the diagnosis of invasive fungal infection by reviewing medical charts of at-risk patients, performing a case-control study to determine risk factors for infection, instituting wet mopping to clean all floors, providing N95 masks to protect patients outside high-efficiency particulate air (HEPA)-filtered areas, altering traffic patterns into the unit, and performing molecular typing of selected Aspergillus flavus isolates. To assess the environment, we verified pressure relationships between the rooms and hallway and between buildings, and we compared the ability of large-volume (1,200 L) and small-volume (160 L) air samplers to detect Aspergillus spores. RESULTS: Of 29 potential invasive aspergillosis cases, 21 were confirmed by medical chart review. Risk factors for developing invasive aspergillosis included the length of time since malignancy was diagnosed (odds ratio [OR], 1.0; P=.05) and hospitalization in a patient room located near a stairwell door (OR, 3.7; P=.05). Two of five A. flavus patient isolates were identical to one of the environmental isolates. The pressure in most of the rooms was higher than in the corridors, but the pressure in the oncology unit was negative with respect to the physically adjacent hospital; consequently, the unit acted essentially as a vacuum that siphoned non-HEPA-filtered air from the main hospital. Of the 78 samples obtained with a small-volume air sampler, none grew an Aspergillus species, whereas 10 of 40 cultures obtained with a large-volume air sampler did. CONCLUSIONS: During active construction, Aspergillus spores may have entered the oncology unit from the physically adjacent hospital because the air pressure differed. Guidelines that establish the minimum acceptable pressures and specify which pressure relationships to test in healthcare settings are needed. Our data show that large-volume air samples are superior to small-volume samples to assess for Aspergillus in the healthcare environment.