antibiotic therapy was left as ceftriaxone and vancomycin. (If the Gram stain had
revealed Gram-positive bacilli, then the empiric antibiotics might have been changed to
ampicillin plus gentamicin because of the possibility of infection with L. monocyto-
genes.) Later studies confirmed that the meningitis was due to S. pneumoniae, and he
was treated with ceftriaxone for an additional 12 days. He made a complete and
uneventful recovery.
Patient 2.This 36-year-old female was brought to the emergency department at
1610 h by her husband. She had been unwell for several days. Over the preceding two
days her family had noted a personality change with bizarre behavior; she had even
complained of smelling odors that no one else could smell (i.e., she was having olfac-
tory hallucinations). On the preceding day, she had developed episodes in which she
would stare blankly for several minutes, sometimes licking her lips, while appearing to
be in a dream state with altered consciousness (i.e., she was having complex-partial
seizures). On the day of her presentation to hospital, she had a severe headache with
fever. She collapsed to the ground and had a generalized seizure with body twitching.
Physical examination revealed that she was confused. Her speech was abnormal in that
she was having trouble forming the words to express herself. A CT scan of the brain
showed asymmetrical areas of swelling in both temporal lobes of her brain.
A clinical diagnosis of viral encephalitis secondary to Herpes simplexwas made.
Therapy was started immediately. She was given acyclovir intravenously as an antiviral
agent. To address the brain swelling she was given dexamethasone, an anti-inflammatory
corticosteroid hormone. Since she was having seizures, she was also intravenously
“loaded” with phenytoin, an anticonvulsant drug. She survived this acute illness and
was discharged home 15 days later. She was left with mild, but definite, memory diffi-
culties. Fourteen months later, she developed epilepsy, requiring long-term treatment
with carbamazepine.
9.9 Drug Design of Therapies and Antidotes for Toxins
The industrial revolution brought many advances in technology; it also brought
increased problems with pollution and environmental toxins. Humans now live in an
environment that is rich in man-made chemicals. Currently, there are more than 65,000
chemicals in common use with approximately 400 new chemicals entering the envi-
ronment on a yearly basis. Not surprisingly, toxicology may assume a role of increas-
ing importance within the realm of human health.
Toxicologyis the science dedicated to the study of the harmful effects of chemical
and physical agents on living systems, especially humans. Occupational toxicology
deals with exposure to chemicals within the workplace environment. Environmental
toxicology, on the other hand, deals with the deleterious health effects of chemicals and
pollutants within the environment as a whole. The magnitude of the toxicity experi-
enced by an exposed human is dependent upon a number of factors, including route of
exposure (topical vs. inhaled), duration of exposure (acute vs. chronic), quantity of
exposure (low-level vs. high-level), and presence of mixtures (synergistic effects of two
toxins, potentiation of one toxin by another). There are also a number of environmental
considerations when assessing toxicology. If exposure to a contaminant is sufficiently
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