1. An otherwise healthy 8-month-old male was brought to a local hospital with a one-week history of
dehydration, lethargy, and constipation. Upon admission, he was referred to the pediatric
neurology team due to noted "floppiness" in his limbs, "droopiness" in his eyes, and cyanosis.
According to his mother, his diet included breast milk, pureed fresh fruits/vegetables, and raw
honey. A full blood count (FBC) revealed neutropenia, indicating an invasive bacterial infection.
He was started on penicillin antibiotics and underwent a comprehensive septic workup. However,
despite adequate rehydration and antimicrobial therapy, his clinical status deteriorated, exhibiting
a decreased respiratory rate requiring intubation and mechanical ventilation. Blood testing for
bacterial exotoxin yielded a positive result - Gram-positive *Clostridium botulinum*, the causative
agent of foodborne botulism. This exotoxin is released and spreads when bacterial cells reproduce
and are lysed (damaged/ killed). The CDC was notified about the case and was sent to investigate.
a. Define the terms sign and symptom and indicate at least three of each from the case study
above. (5 points)
b. Name and describe the etiologic steps the CDC could use to determine which food
contained the same causative agent that was found in the patient's system. Why might
this bacterium be difficult to culture and identify once ingested? (Hint: What category of
microbial disease is botulism). (5 points)
c. The CDC determined that the honey contained the same strain of *C. botulinum* found in
the patient. During testing, they determined that when the honey was heated above
100°F, the *C. botulinum* and its toxins survived. How were the bacteria still able to cause
infection after heating? Explain the process/ structures involved. (5 points)
d. Botulism treatment usually includes administering antitoxin, inducing vomiting, and
ventilator use, but no antibiotics. Describe the basic steps that Gram-positive *C.
botulinum* would use to build/repair its cell wall and explain why using a cell wall
inhibitor like penicillin would not be selectively toxic to the host. (5 points)
e. *C. botulinum* is an anaerobic peritrichous diplobacillus.
• Describe/ draw what its surface morphology would look like under magnification.
(2 points)
• If its environment suddenly became oxygenated, explain how would it move
towards a more suitable environment. (3 points)
2. Portable restrooms ("Porta-potties") often contain a blue dye - biocidal disinfectants
(didecyldimethylammonium chloride & polyhexamethylene guanidine), fragrance, and
surfactants. These chemicals are used to neutralize waste and odor within the restroom but are
highly toxic when discharged to landfills and wastewater treatment plants as biocide-
contaminated fecal sludge (FS). After analyzing the FS, researchers found that the common
opportunistic fecal bacterium, *Alcaligenes faecalis*, is resistant to the biocidal agents and able to
detoxify them in aerobic and anaerobic conditions. They propose using the bacterium to remove
to biocides. Based on the information provided, what type of bioremediation is being
considered? Provide at least 2 specific pros and 2 specific cons of using this bioremediation
method. As the local microbiologist, propose at least one alternative bioremediation method. (5
points)
