Acute necrotizing encephalopathy associated with parainfluenza virus in a Caucasian child.

Acute necrotizing encephalopathy is a severe parainfectious disorder with a clear racial predilection for Oriental children living in the Far East. The prognosis was originally reported as grave; however, a mild form of the disease has recently been described. A case of parainfluenza virus-associated acute necrotizing encephalopathy in a Caucasian child with a mild clinical course and excellent prognosis is presented. In this patient, the initial clinical picture was not very impressive, and the diagnosis was delayed until the third week of the illness, when neuroimaging was performed. Two months later, clinical and neuroimaging findings had almost completely resolved. Suggested criteria for a benign prognosis, such as normal liver function and cerebrospinal fluid protein levels, asymmetric thalamic lesions, and no brainstem involvement, were relevant in the present case. An extended diagnostic work-up for metabolic, vascular, coagulation, and infectious diseases was negative apart from a seroconversion for parainfluenza virus. To our knowledge, this is the first reported case of acute necrotizing encephalopathy associated with parainfluenza virus infection. Acute necrotizing encephalopathy, especially in the mild form, might not be fully recognized and could be underdiagnosed in Europe, where the reported incidence of the syndrome is very low.

Modification of Niven's medium for the enumeration of histamine-forming bacteria and discussion of the parameters associated with its use.

The objective of this study was to improve Niven's medium (NM) for the optimized enumeration of histamine-forming bacteria (HFB). The parameters modified related to solidification of the agar at low pH values (pH 5.3 to 5.8), incubation time (24, 48, and 72 h) and temperature (30 and 37 degrees C), number of colonies developed on the plate to allow enumeration of HFB, and color differentiation. Strains of HFB, Morganella morganii, Klebsiella pneumoniae, and Hafnia alvei were examined for their ability to change color on NM. The three microorganisms produced different colors on the medium, which can be used for preliminary identification of HFB. Quantitative analysis of HFB proved to be achievable, with the prerequisite that only 1 to 80 colonies developed on the medium allow effective enumeration. A larger number of colonies results in color development throughout the medium, making the distinction between HFB and other bacteria unachievable. Growth of prolific HFB was noticeably better at pH values from 5.3 to 5.5, compared to 6.3, on NM. Growth at 5.3 and 5.5 on NM also presented a significant advantage in comparison to growth on plate count agar (PCA; pH 7) at the same incubation temperature. The increased agar concentration of 3% was found to give better solidification at pH 5.3 to 6.0, compared to 2%. This agar concentration also allows autoclaving for 12 min at 121 degrees C, overcoming the hydrolysis problems that appear at the lower concentration of 2%. The construction of a color chart for the recognition of the pH change due to histidine decarboxylase activity was also achieved.