Case study #6 Clostridium botulinum is the causative agent of botulism. This Gram-positive, anaerobic bacillus is commonly found on plants, in soil and water, and in the intestinal tract of some animals. The main virulence factor of C. botulinum is botulism toxin, which is a protein neurotoxin that causes muscle paralysis. Death results from paralysis of respiratory muscles. Genetic analysis has led to the understanding that C. botulinum has acquired its toxin genes from lysogenic bacteriophages. Adults who ingest C. botulinum spores alone generally do not become ill. However, adult botulism will result after ingestion of food containing botulinum toxin. Boiling and common chemical treatments used for water denatures botulism toxin. Infantile botulism, rather, results after children under the age of one ingest foods, such as honey, which contains C. botulinum spores but no botulinum toxin. Once inside the infant gut, these spores germinate and botulism toxin is produced after colonization. Treatment for botulism requires injections of botulinum antitoxin, pre-made antibodies that are administered to the patient as quickly as possible.   What is the reservoir of C. botulinum?

Case study #6 Clostridium botulinum is the causative agent of botulism. This Gram-positive, anaerobic bacillus is commonly found on plants, in soil and water, and in the intestinal tract of some animals. The main virulence factor of C. botulinum is botulism toxin, which is a protein neurotoxin that causes muscle paralysis. Death results from paralysis of respiratory muscles. Genetic analysis has led to the understanding that C. botulinum has acquired its toxin genes from lysogenic bacteriophages. Adults who ingest C. botulinum spores alone generally do not become ill. However, adult botulism will result after ingestion of food containing botulinum toxin. Boiling and common chemical treatments used for water denatures botulism toxin. Infantile botulism, rather, results after children under the age of one ingest foods, such as honey, which contains C. botulinum spores but no botulinum toxin. Once inside the infant gut, these spores germinate and botulism toxin is produced after colonization. Treatment for botulism requires injections of botulinum antitoxin, pre-made antibodies that are administered to the patient as quickly as possible.   Choose all that apply. What (which) levels of protein structure are destroyed after exposing a sample of botulinum toxin to boiling water or water treatment chemicals?

Case study #6 Clostridium botulinum is the causative agent of botulism. This Gram-positive, anaerobic bacillus is commonly found on plants, in soil and water, and in the intestinal tract of some animals. The main virulence factor of C. botulinum is botulism toxin, which is a protein neurotoxin that causes muscle paralysis. Death results from paralysis of respiratory muscles. Genetic analysis has led to the understanding that C. botulinum has acquired its toxin genes from lysogenic bacteriophages. Adults who ingest C. botulinum spores alone generally do not become ill. However, adult botulism will result after ingestion of food containing botulinum toxin. Boiling and common chemical treatments used for water denatures botulism toxin. Infantile botulism, rather, results after children under the age of one ingest foods, such as honey, which contains C. botulinum spores but no botulinum toxin. Once inside the infant gut, these spores germinate and botulism toxin is produced after colonization. Treatment for botulism requires injections of botulinum antitoxin, pre-made antibodies that are administered to the patient as quickly as possible.   What is the reservoir of C. botulinum?

After interferon attaches to a cell

Choose all that apply: Components of the innate immunity include which of the following?

Case study #5 Listeria monocytogenes is a chemoheterotrophic facultative anaerobic Gram-positive bacterium that can act as a human pathogen or as a saprobe, depending on its environment. This bacillus-shaped cell is motile, moving with peritrichous flagella. This bacterium has a high salt tolerance and can multiply readily at 4 oC (refrigerator temperatures). L. monocytogenes is part of the normal gut microbiota of many farm animals, including cows. Deli meats, hot dogs, and unpasteurized cheese and milk are likely sources of this pathogen. Many antibiotics can be used to treat infection with L. monocytogenes, including drugs that target peptidoglycan biosynthesis, the small ribosomal subunit of bacteria, and folic acid biosynthesis.   The oxygen requirements of L. monocytogenes can be described as:

Case study #2 Human Immunodeficiency Virus (HIV) is an enveloped retrovirus that has humans as its only reservoir. The spikes on HIV specifically bind to CD4 molecules of specific leukocytes and lymphocytes. After the viral genetic material is reverse transcribed by an enzyme known for its high error rate and poor proofreading, it is integrated into the host cell’s chromosome. The virus then enters a period of latency. When activated, viral proteins are made using the same machinery and mechanisms as typical host cell proteins. Rapid viral replication results in the death of the host cell. A person with HIV has progressed to clinical AIDS when CD4 cells fall below 200 cells per cubic millimeter of blood. (The CD4 count of a healthy adult/adolescent ranges from 500 cells/mm3 to 1,200 cells/mm3.)   AIDS results when HIV is actively and rapidly replicating in CD4 cells, resulting in the death of large numbers of CD4 cells. The loss of CD4 cells leads to people with AIDS being very susceptible to infection by ________________ that do not infect people with healthy immune systems.

Extra credit case study In August 2014, a 68-year-old man sustained a deep bite to his left fourth and fifth fingers from his pet African gray parrot. The gentleman had a past medical history of chronic obstructive pulmonary disease, for which he took regular inhaled steroids. He was also severely affected by osteoarthritis, for which he took long-acting morphine as analgesia. A day following the parrot bite, he saw his family practitioner for a consultation. The practitioner noted a laceration over the fourth proximal interphalangeal phalanx (PIP) with reddening of the surrounding tissues, and a course of oral antibiotics that have a broad spectrum against most Gram positive and Gram negative bacteria was prescribed for a presumed diagnosis of bacterial cellulitis (skin infection)… In October 2015, the patient again visited his general practitioner with worsening fourth finger swelling and erythema and a new fleshy nodule on the dorsal aspect of the left wrist. In November 2015, a rheumatologist injected steroids into the fourth PIP joint. In December 2015, the fourth PIP wound reopened and his entire left hand became red and swollen. The orthopedic team performed an initial washout with debridement, and amputation was considered. In February 2016, a second washout was performed from which deep tissue swabs showed non-nucleated acid-fast bacilli on a smear. A comprehensive medical history taken in February 2016 revealed that, in addition to the African gray parrot, the patient kept tropical fish and had cleaned the fish tank thoroughly following the parrot bite. The organism identified as the cause of this man’s infection is a naturally occurring aquatic organism found in freshwater and salt water. In humans, it predominantly causes soft tissue infections following exposure to contaminated water. The most common presentation is “fish tank granuloma”, i.e., hand infection following exposure to fish tank water. The majority of cases have a preceding injury to the hand (e.g., bites, abrasions, or puncture wounds) prior to the exposure that allowed entry of the organism through the dermis and into the soft tissue.   As this man became infected due to direct interaction with animals, his infection can be described as a ___________ infection.

Case study #3 Dental caries (dental decay) is the result of solubilization (dissolving) of tooth enamel by acid. The microbes associated with cavities, usually the Gram-positive Streptococcus mutans and Lactobacillus species living in biofilms as plaque, produce organic acids as the waste product of a specific metabolic pathway. Regular tooth brushing and chewing gum after meals, which increases saliva production, and are the two leading methods that can be preformed daily to prevent tooth decay.   Choose all that apply: How do the microbes living as plaque differ from their free-living forms?

Case study #3 Dental caries (dental decay) is the result of solubilization (dissolving) of tooth enamel by acid. The microbes associated with cavities, usually the Gram-positive Streptococcus mutans and Lactobacillus species living in biofilms as plaque, produce organic acids as the waste product of a specific metabolic pathway. Regular tooth brushing and chewing gum after meals, which increases saliva production, and are the two leading methods that can be preformed daily to prevent tooth decay.   Choose all that apply: How do the microbes living as plaque differ from their free-living forms?