Elevated Cerebrospinal Fluid and Serum Adenosine Deaminase Activities in Experimental Listeria Monocytogenes Meningoencephalitis

Abstract

Listeriosis is a severe infectious disease occurring both in humans and in most other animal species caused by Listeria monocytogenes (L. monocytogenes) that can lead to severe meningoencephalitis. Elevated ADA activities have been demonstrated in the cerebrospinal fluid (CSF) in meningitis with different etiologies. However, data on ADA activities in CSF and serum associated with listerial meningoencephalitis is limited. Thus, the present study was designed to investigate the changes in the CSF and serum ADA activities and whether there is a correlation between CSF and serum ADA in the experimental model of listeriosis. Twenty adult white New Zealand rabbits of both sexes were used in this study. Fourteen rabbits were infected by intracerebral inoculation of L. monocytogenes 1/2a and 6 healthy rabbits were included in the study as the control group. CSF samples were obtained by puncture of the cisterna magna. Blood was sampled from the auricular vein of rabbits. ADA activity was determined using the colorimetric method. Mean±SD ADA activities in the CSF and serum were 14.98±3.26 U/L and 17.71±3.41 U/L in infected rabbits, respectively, while 4.72±1.86 U/L and 6.89±3.00 U/L in healthy rabbits. CSF and serum ADA activities showed significant alteration in rabbits with experimental listeriosis compared to control rabbits (p<0.001). A positive correlation was found between CSF and serum ADA activities in infected rabbits (r=0.65, p<0.05), but not in healthy rabbits. These findings imply that ADA plays a role in this disease process. In conclusion, CSF and serum ADA measurements may be used as a supplementary biochemical test in combination with clinical and laboratory findings of listerial meningoencephalitis.