You have recently identified a new toxin. It is produced by a Gram-negative bacterium. It is composed mostly of protein, has high toxicity, and is not heat stable. You also discover that it targets liver cells. Based on these characteristics, how would you classify this toxin?

Choose all that apply: What is/are current effective method(s) of prevention of an HIV infection?

Soil and water are sites where certain pathogens can be found in the natural world.

Case study #1 NDM-1 is an enzyme that hydrolyzes and inactivates nearly all known β-lactam-class antibiotics. This enzyme requires a metallic ion, usually zinc, to catalyze the hydrolysis reaction. The gene encoding NDM-1 is found on a conjugative plasmid and is efficiently transferred to many Gram negative bacteria.   Choose all that apply: The cell envelope of bacteria that receive the ndm-1 gene contain:

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.   Which describes what you would see if you Gram-stained a pure culture of Streptococcus mutans?

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.   Which describes what you would see if you Gram-stained a pure culture of Streptococcus mutans?

Case study #4 Plasmodium falciparum is the most virulent causative agent of malaria. This parasite has a trophozoite form that must undergo a life cycle within the gut of the female Anopheles mosquito to be naturally transmitted to the next host. The parasite also has separate trophozoite forms in the liver and blood of humans. If the malaria parasite is introduced into a pregnant woman, it can cross the placental barrier and infect the developing fetus. People at increased risk for malaria infection are children under 5 years old, pregnant women, and people with AIDS (active HIV infection).   True/False: Chloramphenicol, which binds to the 50S ribosomal subunit, would be effective at treating a P. falciparum infection.

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.

Case study #4 Plasmodium falciparum is the most virulent causative agent of malaria. This parasite has a trophozoite form that must undergo a life cycle within the gut of the female Anopheles mosquito to be naturally transmitted to the next host. The parasite also has separate trophozoite forms in the liver and blood of humans. If the malaria parasite is introduced into a pregnant woman, it can cross the placental barrier and infect the developing fetus. People at increased risk for malaria infection are children under 5 years old, pregnant women, and people with AIDS (active HIV infection).   True/False: Chloramphenicol, which binds to the 50S ribosomal subunit, would be effective at treating a P. falciparum infection.

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.   While L. monocytogenes replicates at 4 oC, it cannot replicate on foods that are frozen (0 oC). This is because