The Role of Zinc Deficiency in Bacterial Meningitis
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Date
2004-11-17
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Abstract
Background: Zinc is an essential trace element that is crucial for immune system function. Zinc deficient animals have been shown to have a suppressed immune response and high susceptibility to infections. However, the role of zinc has not been specifically studied in bacterial meningitis. Bacterial meningitis is a disease of worldwide distribution, which is rapidly fatal if untreated and may leave many survivors with neurological sequelae.
Method: Female wistar rats were fed a zinc deficient diet for two weeks to make them zinc deficient. Control rats were fed normal chow. To induce meningitis, Streptococcus pneumoniae type III (~106.5cfu) was inoculated via a cisternal puncture. At 24hrs rats were retapped and cerebrospinal fluid (CSF) taken for white blood cell counts and quantitative cultures. Blood culture and serum zinc concentration were determined. The time of death was noted until 48hrs, at which time, animals that were still alive were sacrificed.
Results: Twenty-four hours after inoculation, bacteremia persisted in 87.5% (14/16) of the zinc deficient rats but only in 37.5% (9/24) of control rats (P=0.003). The CSF bacterial concentrations were slightly but not significantly higher in the zinc deficient rats (1og10CFU/ml, MEAN± SEM, 6.55±0.28 vs. 6.12±0.32, P=0.69). The CSF white cell concentration in the zinc deficient rats was also slightly but not significantly higher
(17,600±3070/mm3 vs. 11,340±1970/mm3, p=0.3). Serum TNF-α concentrations were statistically different between the zinc deficient and pair fed groups (721.2 ± 211.4 pg/I vs. 215.8 ± 40.7lpg/l, p=0.0468). The mortality at 24 hrs, 36hrs and 48hrs after inoculation was 40%, 100% and 100% (N=10) respectively for zinc deficient rats and 0%, 54.5% and 90.9% (N=1 1) respectively for control rats (p=0.035 at 24 and 36 hrs). Conclusion: These data show that zinc deficient rats with S. pneumoniae meningitis have more persistent bacteraemia and shorter survival following bacterial challenge.
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A thesis presented to the Department of Clinical Microbiology, School of Medical Sciences, College of Health Sciences
Kwame Nkrumah University of Science and Technology in partial
fulfilment of the requirements for the award of Master of Science, 2004